Flood monitoring.

27/01/2020
Monitoring is an essential component of natural flooding management, helping to define appropriate measures, measure their success, keep stakeholders informed, identify mistakes, raise alarms when necessary, inform adaptive management and help guide future research.
GreatFenGB

Great Fen showing Holme Fen woods top left and new ponds and meres in April

Flooding is a natural process, but it endangers lives and causes heavy economic loss. Furthermore, flood risk is expected to increase with climate change and increased urbanisation, so a heavy responsibility lies with those that allocate funding and formulate flood management strategy. In the following article, Nigel Grimsley from OTT Hydromet explains how the success of such plans (both the design and implementation) depend on the accuracy and reliability of the monitoring data upon which they rely.

Climate projections for Britain suggest that rainfall will increase in winter and decrease in summer, and that individual rainfall events may increase in intensity, especially in winter. This paradigm predicates an increased risk of flooding.

Emphasising the urgent need for action on flood risk, (British) Environment Agency chairwoman Emma Howard Boyd, has said that on current trends, global temperature could rise between 2 deg C and 4 Deg C by 2100 and some communities may even need to move because of the risk of floods. Launching a consultation on the agency’s flood strategy, she said: “We can’t win a war against water by building away climate change with infinitely high flood defences.”

In response, Mike Childs, head of science at Friends of the Earth, said: “Smarter adaptation and resilience building – including natural flood management measures like tree-planting – is undeniably important but the focus must first and foremost be on slashing emissions so that we can avoid the worst consequences of climate chaos in the first place.”

Historically, floodplains have been exploited for agricultural and urban development, which has increased the exposure of people, property and other infrastructure to floods. Flood risk management therefore focused on measures to protect communities and industry in affected areas. However, flood risk is now addressed on a wider catchment scale so that initiatives in one part of a catchment do not have negative effects further downstream. This catchment based approach is embodied within the EU Floods Directive 2007/60/EC, and in recent years, those responsible for flood management have increasingly looked for solutions that employ techniques which work with natural hydrological and morphological processes, features and characteristics to manage the sources and pathways of flood waters. These techniques are known as natural flood management (NFM) and include the restoration, enhancement and alteration of natural features but exclude traditional flood defence engineering that effectively disrupts these natural processes.

NFM seeks to create efficiency and sustainability in the way the environment is managed by recognising that when land and water are managed together at the catchment scale it is possible to generate whole catchment improvements with multiple benefits.

Almost all NFM techniques aim to slow the flow of water and whilst closely connected, can be broadly categorised as infiltration, conveyance and storage.

Infiltration
Land use changes such as set-aside, switching arable to grassland or restricted hillside cropping, can improve infiltration and increase water retention. In addition, direct drilling, ‘no-till’ techniques and cross slope ploughing can have a similar effect. These land use techniques are designed to reduce the soil compaction which increases run-off. Livestock practices such as lower stocking rates and shorter grazing seasons can also help. Field drainage can be designed to increase storage and reduce impermeability, which is also aided by low ground pressure vehicles. The planting of shrubs and trees also helps infiltration and retention by generating a demand for soil moisture, so that soils have a greater capacity to absorb water. Plants also help to bind soil particles, resulting in less erosion – the cause of fertility loss and sedimentation in streams and rivers.

Conveyance
Ditches and moorland grips can be blocked to reduce conveyance, and river profiles can be restored to slow the flow. In the past, peats and bogs have been drained to increase cropping areas, but this damages peatlands and reduces their capacity to retain water and store carbon. The restoration of peatland therefore relies on techniques to restore moisture levels. Pumping and drainage regimes can be modified, and landowners can create strategically positioned hedges, shelter belts and buffer strips to reduce water conveyance.

Storage
Rivers can be reconnected with restored floodplains and river re-profiling, leaky dams, channel works and riparian improvements can all contribute to improved storage capability. In urban areas permeable surfaces and underground storage can be implemented, and washlands and retention ponds can be created in all areas. As mentioned above, the re-wetting of peatland and bogs helps to increase storage capacity.

Many of the effects of NFM might be achieved with the re-introduction of beavers, which build dams that reduce peak flows, create pools and saturate soil above their dams. The dams also help to remove pollutants such as phosphates. Beavers do not eat fish, instead preferring aquatic plants, grasses and shrubs during the summer and woody plants in winter. Beavers are now being introduced in a number of areas in trials to determine their value in the implementation of NFM. One of the key benefits offered by beavers is their ability to quickly repair and rebuild dams that are damaged during extreme weather. However, whilst the potential benefits of beavers are well known, several groups have expressed concern with the prospect of their widespread introduction. For example, farmers and landowners may find increased areas of waterlogged land due to blocked drainage channels. In addition, dams present a threat to migratory fish such as salmon and sea trout.

Beavers are native to Britain and used to be widespread, but they were hunted to extinction during the 17th century. However, other non-native species such as signal crayfish can have a detrimental effect on flood protection because they burrow into river banks causing erosion, bank collapse and sediment pollution. Signal crayfish are bigger, grow faster, reproduce more quickly and tolerate a wider range of conditions than the native white-clawed crayfish. Signal crayfish are also voracious predators, feeding on fish, frogs, invertebrates and plants, and as such can create significant negative ecological effects.

NFM benefits
NFM provides protection for smaller flood events, reduces peak flooding and delays the arrival of the flood peak downstream. However, it does not mitigate the risk from extreme flood events. Effective flood management strategy therefore tends to combine NFM with hard engineering measures. Nevertheless, NFM generally provides a broader spectrum of other benefits.

The creation of new woodlands and wetlands produces biodiverse habitats with greater flood storage capacity. They also enable more species to move between habitats. NFM measures that reduce soil erosion, run-off and sedimentation also help to improve water quality and thereby also improve habitats. In particular, these measures lower nutrient and sediment loading lower in the catchment; two issues which can have dramatic effects on water quality and amenity.

Land use and land management measures help to reduce the loss of topsoil and nutrients. This improves agricultural productivity and lowers the cost of fertilizers. Furthermore, a wide range of grants are available for NFM measures, such as the creation of green spaces and floodplains, to make them more financially attractive to farmers and landowners.

Many NFM measures help in the fight against climate change. For example, wetlands and woodlands are effective at storing carbon and removing carbon dioxide from the atmosphere. Measures that reduce surface run off and soil erosion, such as contour cultivation, can also reduce carbon loss from soil.

Monitoring NFM
Given the wide range of potential NFM benefits outlined above, the number and type of parameters to be monitored are likely to be equally diverse. Baseline data is essential if the impacts of implemented measures are to be assessed, but this may not always be deliverable. For example, it may only be possible to collect one season of data prior to a five year project. However, it may be possible to secure baseline data from other parties. In all instances data should of course be accurate, reliable, relevant and comparable.

Monitoring data should be used to inform the design of NFMs. For example, a detailed understanding of the ecology, geomorphology, hydrology and meteorology of the entire catchment will help to ensure that the correct measures are chosen. These measures should be selected in partnership with all stakeholders, and ongoing monitoring should provide visibility of the effects of NFM measures. Typically stakeholders will include funders, project partners, local communities, landowners, regulators and local authorities.

Since NFM measures are designed to benefit an entire catchment, it is important that monitoring is also catchment-wide. However, this is likely to be a large area so there will be financial implications, particularly for work that is labour-intensive. Consequently, it will be necessary to prioritise monitoring tasks and to deploy remote, automatic technology wherever it is cost-effective.

OTT ecoN with wiper

OTT ecoN Sensor

Clearly, key parameters such as rainfall, groundwater level, river level and surface water quality should be monitored continuously in multiple locations if the benefits of NFM are to be measured effectively. It is fortunate therefore that all of these measurements can be taken continuously 24/7 by instruments that can be left to monitor in remote locations without a requirement for frequent visits to calibrate, service or change power supplies. As a business OTT Hydromet has been focused on the development of this capability for many years, developing sensors that are sufficiently rugged to operate in potentially aggressive environments, data loggers with enormous capacity but with very low power requirement, and advanced communications technologies so that field data can be instantly viewed by all stakeholders.

Recent developments in data management have led to the development of web-enabled data management solutions such as Hydromet Cloud, which, via a website and App, delivers the backend infrastructure to receive, decode, process, display and store measurement data from nearly any remote hydromet monitoring station or sensor via a cloud-based data hosting platform. As a consequence, alarms can be raised automatically, which facilitates integration with hard engineering flood control measures. Hydromet Cloud also provides access to both current and historic measurement data, enabling stakeholders to view the status of an entire catchment on one screen.

Holme Fen – a monitoring lesson from the 1850s

Holme Fen post HS

Holme Fen post

Surrounded by prime agricultural land to the south of Peterborough (Cambridgeshire,GB) , the fens originally contained many shallow lakes, of which Whittlesey Mere was the largest, covering around 750 hectares in the summer and around twice that in the winter. Fed by the River Nene, the mere was very shallow and was the last of the ‘great meres’ to be drained and thereby converted to cultivatable land.

Led by William Wells, a group of local landowners funded and arranged the drainage project, which involved the development of a newly invented steam powered centrifugal pump which was capable of raising over 100 tons of water per minute by 2 or 3 feet. A new main drain was constructed to take water to the Wash. Conscious of the likely shrinking effect of drainage on the peaty soil, Wells instigated the burial of a measurement post, which was anchored in the Oxford Clay bedrock and cut off at the soil surface. In 1851 the original timber post was replaced by a cast iron column which is believed to have come from the Crystal Palace in London.

By installing a measurement post, Wells demonstrated remarkable foresight. As the drainage proceeded, the ground level sank considerably; by 1.44 metres in the first 12 years, and by about 3 metres in the first 40 years. Today, around 4 metres of the post is showing above ground, recording the ground subsidence since 1852. The ground level at Holme Post is now 2.75 metres below sea level – the lowest land point in Great Britain.
Several complications have arisen as a result of the drainage. Firstly, there has been a huge impact in local ecology and biodiversity with the loss of a large area of wetland. Also, as the ground level subsided it became less sustainable to pump water up into the main drain.

Holme Fen is now a National Nature Reserve, managed by Natural England, as is the nearby Woodwalton Fen. They are both part of the Great Fen Project, an exciting habitat restoration project, involving several partners, including the local Wildlife Trust, Natural England and the Environment Agency. At Woodwalton, the more frequent extreme weather events that occur because of climate change result in flooding that spills into the reserve. In the past, this was a good example of NFM as the reserve provided a buffer for excess floodwater. However, Great Fen Monitoring and Research Officer Henry Stanier says: “Floodwater increasingly contains high levels of nutrients and silt which can harm the reserve’s ecology, so a holistic, future-proof strategy for the area is necessary.”

Applauding the farsightedness of William Wells, Henry says: “As a conservationist I am often called in to set up monitoring after ecological recovery has begun, rather than during or even before harm has taken place. At the Wildlife Trust, we are therefore following the example provided by Wells, and have a network of monitoring wells in place so that we can monitor the effects of any future changes in land management.

“For example, we are setting up a grant funded project to identify the most appropriate crops for this area; now and in the future, and we are working with OTT to develop a monitoring strategy that will integrate well monitoring with the measurement of nutrients such as phosphate and nitrate in surface waters.”

Summary
Monitoring provides an opportunity to measure the effects of initiatives and mitigation measures. It also enables the identification of trends so that timely measures can be undertaken before challenges become problems, and problems become catastrophes.

Monitoring is an essential component of NFM, helping to define appropriate measures, measure their success, keep stakeholders informed, identify mistakes, raise alarms when necessary, inform adaptive management and help guide future research.

#Environment @OTTHydromet @EnvAgency @friends_earth


Managing NOx gas emissions from combustion.

26/09/2019
Pollution can only be managed effectively if it is monitored effectively.

James Clements

As political pressure increases to limit the emissions of the oxides of nitrogen, James Clements, Managing Director of the Signal Group, explains how the latest advances in monitoring technology can help.

Nitrogen and oxygen are the two main components of atmospheric air, but they do not react at ambient temperature. However, in the heat of combustion, such as in a vehicle engine or within an industrial furnace or process, the gases react to form nitrogen oxide (NO) and nitrogen dioxide (NO2). This is an important consideration for the manufacturers of combustion equipment because emissions of these gases (collectively known as NOx) have serious health and environmental effects, and are therefore tightly regulated.

Nitrogen dioxide gas is a major pollutant in ambient air, responsible for large numbers of premature deaths, particularly in urban areas where vehicular emissions accumulate. NO2 also contributes to global warming and in some circumstances can cause acid rain. A wide range of regulations therefore exist to limit NOx emissions from combustion sources ranging from domestic wood burners to cars, and from industrial furnaces and generators to power stations. The developers of engines and furnaces therefore focus attention on the NOx emissions of their designs, and the operators of this equipment are generally required to undertake emissions monitoring to demonstrate regulatory compliance.

The role of monitoring in NOx reduction
NOx emissions can be reduced by:

  • reducing peak combustion temperature
  • reducing residence time at the peak temperature
  • chemical reduction of NOx during the combustion process
  • reducing nitrogen in the combustion process

These primary NOx reduction methods frequently involve extra cost or lower combustion efficiency, so NOx measurements are essential for the optimisation of engine/boiler efficiency. Secondary NOx reduction measures are possible by either chemical reduction or sorption/neutralisation. Naturally, the effects of these measures also require accurate emissions monitoring and control.

Choosing a NOx analyser
In practice, the main methods employed for the measurement of NOx are infrared, chemiluminescence and electrochemical. However, emissions monitoring standards are mostly performance based, so users need to select analysers that are able to demonstrate the required performance specification.

Rack Analyser

Infrared analysers measure the absorption of an emitted infrared light source through a gas sample. In Signal’s PULSAR range, Gas Filter Correlation technology enables the measurement of just the gas or gases of interest, with negligible interference from other gases and water vapour. Alternatively, FTIR enables the simultaneous speciation of many different species, including NO and NO2, but it is costly and in common with other infrared methods, is significantly less sensitive than CLD.

Electrochemical sensors are low cost and generally offer lower levels of performance. Gas diffuses into the sensor where it is oxidised or reduced, which results in a current that is limited by diffusion, so the output from these sensors is proportional to the gas concentration. However, users should take into consideration potential cross-sensitivities, as well as rigorous calibration requirements and limited sensor longevity.

The chemiluminescence detector (CLD) method of measuring NO is based on the use of a controlled amount of Ozone (O3) coming into contact with the sample containing NO inside a light sealed chamber. This chamber has a photomultiplier fitted so that it measures the photons given off by the reaction that takes place between NO and O3.

NO is oxidised by the O3 to become NO2 and photons are released as a part of the reaction. This chemiluminescence only occurs with NO, so in order to measure NO2 it is necessary to first convert it to NO. The NO2 value is added to the NO reading and this is equates to the NOx value.

Most of the oxides of nitrogen coming directly from combustion processes are NO, but much of it is further oxidised to NO2 as the NO mixes with air (which is 20.9% Oxygen). For regulatory monitoring, NO2 is generally the required measurement parameter, but for combustion research and development NOx is the common measurand. Consequently, chemiluminescence is the preferred measurement method for development engineers at manufacturer laboratories working on new technologies to reduce NOx emissions in the combustion of fossil fuels. For regulatory compliance monitoring, NDIR (Non-Dispersive Infrared) is more commonly employed.

Typical applications for CLD analysers therefore include the development and manufacture of gas turbines, large stationary diesel engines, large combustion plant process boilers, domestic gas water heaters and gas-fired factory space heaters, as well as combustion research, catalyst efficiency, NOx reduction, bus engine retrofits, truck NOx selective catalytic reduction development and any other manufacturing process which burns fossil fuels.

These applications require better accuracy than regulatory compliance because savings in the choice of analyser are negligible in comparison with the market benefits of developing engines and furnaces with superior efficiency and better, cleaner emissions.

Signal Group always offers non-heated, non-vacuum CLD analysers for combined cycle gas turbine (CCGT) power stations because these stations emit lower than average NOx levels. NDIR analysers typically have a range of 100ppm whereas CLD analysers are much more sensitive, with a lower range of 10ppm. Combustion processes operating with de-NOX equipment will need this superior level of sensitivity.

There is a high proportion of NO2 in the emissions of CCGT plants because they run with high levels of air in the combustion process, so it is necessary to convert NO2 to NO prior to analysis. Most CLD analysers are supplied with converters, but NDIR analysers are not so these are normally installed separately when NDIR is used.

In the USA, permitted levels for NOx are low, and many plants employ de-NOx equipment, so CLD analysers are often preferred. In Europe, the permitted levels are coming down, but there are fewer CCGT Large Plant operators, and in other markets such as India and China, permitted NOx emissions are significantly higher and NDIR is therefore more commonly employed.

In England, the Environment Agency requires continuous emissions monitors (CEMS) to have a range no more than 2.5 times the permitted NOx level, so as a manufacturer of both CLD and NDIR analysers, this can be a determining factor for Signal Group when deciding which analysers to recommend. The UK has a large number of CCGT power plants in operation and Signal Group has a high number of installed CEMS at these sites, but very few new plants have been built in recent years.

New NOx analysis technology
Signal Group recently announced the launch of the QUASAR Series IV gas analysers which employ CLD for the continuous measurement of NOx, Nitric Oxide, Nitrogen Dioxide or Ammonia in applications such as engine emissions, combustion studies, process monitoring, CEMS and gas production.

Chemiluminescence Analyser

The QUASAR instruments exploit the advantages of heated vacuum chemiluminescence, offering higher sensitivity with minimal quenching effects, and a heated reaction chamber that facilitates the processing of hot, wet sample gases without condensation. Signal’s vacuum technology improves the signal to noise ratio, and a fast response time makes it ideal for real-time reporting applications. However, a non-vacuum version is available for trace NOx measurements such as RDE (Real-world Driving Emissions) on-board vehicle testing, for which a 24VDC version is available.

A key feature of these latest instruments is the communications flexibility – all of the new Series IV instruments are compatible with 3G, 4G, GPRS, Bluetooth, Wifi and satellite communications; each instrument has its own IP address and runs on Windows software. This provides users with simple, secure access to their analyzers at any time, from almost anywhere.

In summary, it is clear that the choice of analyser is dictated by the application, so it is important to discuss this with appropriate suppliers/manufacturers. However, with the latest instruments, Signal’s customers can look forward to monitoring systems that are much more flexible and easier to operate. This will improve NOx reduction measures, and thereby help to protect both human health and the environment.


Gas sensing in the purification process of drinking water.

28/08/2019

The processing of clean and safe drinking water is an international issue. Estimates suggest that, if no further improvements are made to the availability of safe water sources, over 135 million people will die from potentially preventable diseases by 2020.1

Even within Britain, water purification and treatment is big business, with £2.1 billion (€2.37b 28/8/2019) being invested by utilities in England and Wales between 2013 and 2014.2 Water purification consists of removing undesirable chemicals, bacteria, solids and gases from water, so that it is safe to drink and use. The standard of purified water varies depending on the intended purpose of the water, for example, water used for fine chemical synthesis may need to be ‘cleaner’ i.e. have fewer chemicals present, than is tolerable for drinking water, the most common use of purified water.

Purification Process
The process of water purification involves many different steps. The first step, once the water has been piped to the purification plant, is filtering to remove any large debris and solids. There also needs to be an assessment of how dirty the water is to design the purification strategy. Some pretreatment may also occur using carbon dioxide to change pH levels and clean up the wastewater to some extent. Here, gas monitors are used to ensure the correct gas levels are being added to the water and unsafe levels of the gas do not build up.

The following steps include chemical treatment, an filtration to remove dissolved ionic compounds.3 Then, disinfection can occur to kill any remaining bacteria or viruses, with additional chemicals being added to provide longer lasting protection.4 At all stages, the water quality must be constantly monitored. This is to ensure that any pollutants have been adequately removed and the water is safe for its intended purpose.

In-line gas monitors are often used as part of the water treatment process as a way of monitoring total organic carbon (TOC) content. Carbon content in water can arise from a variety of sources, including bacteria, plastics or sediments that have not been successfully removed by the filtration process.5 TOC is a useful proxy for water cleanliness as it covers contamination from a variety of different sources.

To use non-dispersive infrared (NDIR) gas monitors to analyze the TOC content of water, a few extra chemical reactions and vaporization need to be performed to cause the release of CO2 gas. The resulting concentration of gas can then be used as a proxy of TOC levels.6 This then provides a metric than can be used to determine whether additional purification is required or that the water is safe for use.

Need for Gas Monitors
NDIR gas sensors can be used as both a safety device in the water purification process as carbon dioxide, methane, and carbon monoxide are some of the key gases produced during the treatment process. 5 The other key use is for analysis of TOC content as a way of checking for water purity.7 NDIR sensors are particularly well suited for TOC analysis as carbon dioxide absorbs infrared light very strongly. This means that even very low carbon dioxide concentrations can be detected easily, making it a highly sensitive measurement approach.6 Other hydrocarbon gases can also easily be detected in this way, making NDIR sensors a highly flexible, adaptable approach to monitoring TOC and dissolved gas content in water.

Sensor Solutions
The need for constant gas monitoring to guide and refine the purification process during wastewater treatment means water purification plants need permanent, easy to install sensors that are capable of continual online monitoring. One of the most effective ways of doing this is having OEM sensors that can be integrated into existing water testing equipment to also provide information on water purity.

These reasons are why Edinburgh Sensors range of nondispersive infrared (NDIR) gas sensors are the perfect solution for water purification plants. NDIR sensors are highly robust with excellent sensitivity and accuracy across a range of gas concentrations. Two of the sensors they offer, the Gascard NG8 and the Guardian NG9 are suitable for detecting carbon monoxide, carbon dioxide or other hydrocarbon gases. If just carbon dioxide is of interest, then Edinburgh Sensors offers are more extensive range of monitors, including the Gascheck10 and the IRgaskiT.11

The advantage of NDIR detection for these gases are the device initial warm-up times are less than 1 minute, in the case of the Guardian NG. It is also capable of 0 – 100 % measurements such gases with a response time of less than 30 seconds from the sample inlet. The readout is ± 2 % accurate and all these sensors maintain this accuracy over even challenging environmental conditions of 0 – 95 % humidity, with self-compensating readout.

The Guardian NG comes with its own readout and menu display for ease of use and simply requires a reference gas and power supply to get running. For water purification purposes, the Gascard is particularly popular as the card-based device is easy to integrate into existing water testing equipment so testing of gases can occur while checking purity. .
Edinburgh Sensors also offers custom gas sensing solutions and their full technical support throughout the sales, installation and maintenance process.

References
1. Gleick, P. H. (2002). Dirty Water: Estimated Deaths from Water-Related Diseases 2000-2020 Pacific. Pacific Institute Researc Report, 1–12.

2. Water and Treated Water (2019), https://www.gov.uk/government/publications/water-and-treated-water/water-and-treated-water

3. Pangarkar, B. L., Deshmukh, S. K., Sapkal, V. S., & Sapkal, R. S. (2016). Review of membrane distillation process for water purification. Desalination and Water Treatment, 57(7), 2959–2981. https://doi.org/10.1080/19443994.2014.985728

4. Hijnen, W. A. M., Beerendonk, E. F., & Medema, G. J. (2006). Inactivation credit of UV radiation for viruses, bacteria and protozoan (oo)cysts in water: A review. Water Research, 40(1), 3–22. https://doi.org/10.1016/j.watres.2005.10.030

5. McCarty, P. L., & Smith, D. P. (1986). Anaerobic wastewater treatment. Environmental Science and Technology, 20(12), 1200–1206. https://doi.org/10.1021/es00154a002

6. Scott, J. P., & Ollis, D. F. (1995). Integration of chemical and biological oxidation processes for water treatment: Review and recommendations. Environmental Progress, 14(2), 88–103. https://doi.org/10.1002/ep.670140212

7. Florescu, D., Iordache, A. M., Costinel, D., Horj, E., Ionete, R. E., & Culea, M. (2013). Validation procedure for assessing the total organic carbon in water samples. Romanian Reports of Physics, 58(1–2), 211–219.

8. Gascard NG, (2019), https://edinburghsensors.com/products/oem/gascard-ng/

9. Guardian NG (2019) https://edinburghsensors.com/products/gas-monitors/guardian-ng/

10. Gascheck (2019), https://edinburghsensors.com/products/oem/gascheck/

11. IRgaskiT (2019), https://edinburghsensors.com/products/oem-co2-sensor/irgaskit/

12. Boxed GasCard (2019) https://edinburghsensors.com/products/oem/boxed-gascard/

 

#Pauto @Edinst

No messing about on river conservation!

06/12/2018

Scientists from the University of Portsmouth have been investigating nutrient concentrations in the Upper River Itchen, in Hampshire (GB), on behalf of Salmon & Trout Conservation (S&TC) to better understand where phosphorus is coming from and how it is impacting river ecology.

The work has been ongoing for over three years and Lauren Mattingley, Science Officer for S&TC says: “Continuous monitoring of phosphorus has improved our understanding of nutrient dynamics in the Itchen. So far, the results from this monitoring have influenced the lowering of discharge limits from watercress companies and trout breeding farms.

“The behaviour of phosphorus in our rivers is relatively poorly understood, and this is often reflected in water quality standards that, in our opinion, lack the scientific evidence to adequately protect the ecology of the UK’s diverse water resources. Research like that which we have commissioned on the Itchen is essential to set informed phosphorus permits to protect our water life.”

Background
The Itchen is a world famous chalk stream; renowned for its fly fishing and clear water. Designated a ‘Special Area of Conservation’ (SAC) the river supports populations of water-crowfoot, Southern damselfly, Bullhead, Brook lamprey, White-clawed crayfish and otters. The upper river does not suffer from wastewater treatment plant discharges, but does support two watercress farms, which have been the focus of initiatives to reduce phosphate concentrations.

S&TC is the only British charity campaigning for wild fish and their habitats. The organisation’s goal is for British waters to support abundant and sustainable populations of wild fish and all other water-dependent wildlife. Within its ‘Living Rivers’ campaign S&TC is seeking to tackle two of the major causes of poor water quality – fine sediment and phosphorus. The Itchen is therefore being treated as a pilot river for their water quality monitoring initiatives.

Phosphorus in fresh water is a major concern globally; mainly because of its role in the formation of algal blooms and eutrophication, which have a harmful effect on water quality and habitats. Under certain conditions, raised phosphate concentrations contribute to the proliferation of nuisance phytoplankton as well as epiphytic and benthic algae. Diffuse sources of phosphate include storm water and agricultural run-off from land, and point sources include septic tanks and wastewater discharges from industry and sewage treatment works. While soluble reactive phosphorus (SRP) is the main concern, because of its availability for aquatic organism growth, other forms of phosphate such as particulate phosphate can contribute to nutrient enrichment.

Efforts to improve the quality of water bodies in Britain have been underway for many years. The EU’s Water Framework Directive (WFD) required Britain to achieve ‘good status’ of all water bodies (including rivers, streams, lakes, estuaries, coastal waters and groundwater) by 2015, but in 2012 only 36% of water bodies were classified as ‘good’ or better.

In 2013 the UK Technical Advisory Group (UKTAG) published recommendations to revise the standards for phosphorus in rivers, because the standards set in 2009 were not sufficiently stringent – in 75% of rivers with clear ecological impacts of nutrient enrichment, the existing standards produced phosphorus classifications of good or even high status! DEFRA (British Government Department looking after environmental matters), therefore, revised the phosphorus standards to lower concentrations. However, the SRP concentration limits vary widely according to the location and alkalinity of the river.

Recognising a gap in the understanding of the relationship between phosphorus and aquatic ecology, S&TC has a unique agreement with the Environment Agency (EA) in Hampshire in which key environmental targets have been established for the Rivers Test and Itchen to help drive ecological improvements. The agreed targets are set around the number of key water insects that should be expected in a 3-minute kick-sweep sample. The targets are for the middle and lower reaches of the catchment to support at least 10 separate mayfly species and 500 freshwater shrimps (Gammarus) – all of which are susceptible to different forms of pollution so their presence provides an effective measure of the environmental health of the river.

S&TC has also conducted research investigating the effects of fine sediment and SRP on the hatching of the blue winged olive, Serratella ignita (Ephemerellidae: Ephemeroptera) a crucial component of the aquatic food chain. The results found that a cocktail of SRP and fine sediment at concentrations exceeding those found in many UK rivers (25 mg/L fine sediment and 0.07 mg/L phosphate) caused 80% of the eggs in the experiment to die. This work was unique because it showed environmental damage caused by phosphorus beyond eutrophication.

River Itchen sampling and analysis
Five automatic water samplers have been strategically located on the river each collecting daily samples. This generates 120 samples per 24 day cycle, which are collected and transferred to the laboratory in Portsmouth. The samples are split into three for the analysis of Total Phosphate, Soluble Reactive Phosphate (SRP) and Total Dissolved Phosphate (TDP). To cope with such a high volume of work, the laboratory in the University of Portsmouth’s School of Earth & Environmental Sciences employs a QuAAtro 5-channel segmented flow autoanalyzer, from SEAL Analytical.

“The QuAAtro has been in heavy use for over 9 years,” says Senior Scientific Officer Dr Adil Bakir. “It has been employed on a number of academic and commercial research projects, and is also used for teaching purposes. As a 5-channel instrument, we are able to study phosphate, nitrate, nitrite, ammonia and silicate, but our work on the River Itchen is focused on the different forms of phosphate.”

The University of Portsmouth’s Environmental Chemistry Analytical Laboratory provides analytical and consultancy services for businesses, universities and other organisations. Dr Bakir says: “Using the QuaAAttro we are able to analyse diverse matrices including river water, sea water and wastewater, and with automatic dilution and high levels of sensitivity, we are able to measure a wide range of concentrations.”

Creating effective discharge consents
The analytical work undertaken by the laboratory at the University of Portsmouth has greatly improved the understanding of the ecology of the River Itchen and thereby informed the development of appropriate discharge consents for the two watercress farms. Effective 1st January 2016, new discharge permits were issued by the Environment Agency that set limits on phosphate discharges to the River Itchen system. For the Vitacress Pinglestone Farm these limits are set at 0.064 mg/L and are measured as an annual mean increase compared to the inlet sample.

S&TC now works closely with Vitacress, monitoring immediately downstream of the discharge so that the effects of the new discharge limit can be effectively assessed.

Looking forward, Lauren says: “The lessons that we have learned on the Itchen are transferrable, and do not just apply to chalk streams. All rivers have their issues and inputs, so proper diagnosis and understanding of how these inputs shape the biology is essential to the successful restoration of degraded systems.

“In an ideal world phosphorus targets would be bespoke, on a river by river basis, and determined by tailored research and proper monitoring.

“River ecology is impacted by a wide variety of factors and whilst nutrients represent a serious risk, it is important for us to understand all of the threats, and the relationships between them. In summary, without high-resolution monitoring, river standards and river restoration efforts will be blind to their consequences.”

#SealAnalytical #Environmental @SalmonTroutCons @_Enviro_News


High frequency monitoring needed to protect UK rivers!

29/06/2018
Nigel Grimsley from OTT Hydrometry describes relatively new technologies that have overcome traditional barriers to the continuous monitoring of phosphate and nitrate.

The science behind nutrient pollution in rivers is still poorly understood despite the fact that nitrate and phosphate concentrations in Britain’s rivers are mostly unacceptable, although an element of uncertainty exists about what an acceptable level actually is. Key to improving our understanding of the sources and impacts of nutrient pollution is high-resolution monitoring across a broad spectrum of river types.

Background

Green Box Hydro Cycle

Phosphates and nitrates occur naturally in the environment, and are essential nutrients that support the growth of aquatic organisms. However, water resources are under constant pressure from both point and diffuse sources of nutrients. Under certain conditions, such as warm, sunny weather and slow moving water, elevated nutrient concentrations can promote the growth of nuisance phytoplankton causing algal blooms (eurtrophication). These blooms can dramatically affect aquatic ecology in a number of ways. High densities of algal biomass within the water column, or, in extreme cases, blankets of algae on the water surface, prevent light from reaching submerged plants. Also, some algae, and the bacteria that feed on decaying algae, produce toxins. In combination, these two effects can lower dissolved oxygen levels and potentially kill fish and other organisms. In consequence, aquatic ecology is damaged and the water becomes unsuitable for human recreation and more expensive to treat for drinking purposes.

In its State of the Environment report, February 2018, the British Environment Agency said: “Unacceptable levels of phosphorus in over half of English rivers, usually due to sewage effluent and pollution from farm land, chokes wildlife as algal blooms use up their oxygen. Groundwater quality is currently deteriorating. This vital source of drinking water is often heavily polluted with nitrates, mainly from agriculture.”

Good ecological status
The EU Water Framework Directive (WFD) requires Britain to achieve ‘good status’ of all water bodies (including rivers, streams, lakes, estuaries, coastal waters and groundwater) by 2015. However, only 36% of water bodies were classified as ‘good’ or better in 2012. Nutrient water quality standards are set by the Department for Environment, Food & Rural Affairs (DEFRA), so for example, phosphorus water quality standards have been set, and vary according to the alkalinity and height above mean sea level of the river. Interestingly, the standards were initially set in 2009, but in 75% of rivers with clear ecological impacts of nutrient enrichment, the existing standards produced phosphorus classifications of good or even high status, so the phosphorus standards were lowered.

Highlighting the need for better understanding of the relationships between nutrients and ecological status, Dr Mike Bowes from the Centre for Ecology & Hydrology has published research, with others, in which the effects of varying soluble reactive phosphate (SRP) concentrations on periphyton growth rate (mixture of algae and microbes that typically cover submerged surfaces) where determined in 9 different rivers from around Britain. In all of these experiments, significantly increasing SRP concentrations in the river water for sustained periods (usually c. 9 days) did not increase periphyton growth rate or biomass. This indicates that in most rivers, phosphorus concentrations are in excess, and therefore the process of eutrophication (typified by excessive algal blooms and loss of macrophytes – aquatic plants) is not necessarily caused by intermittent increases in SRP.

Clearly, more research is necessary to more fully understand the effects of nutrient enrichment, and the causes of algal blooms.

Upstream challenge
Headwater streams represent more than 70% of the streams and rivers in Britain, however, because of their number, location and the lack of regulatory requirement for continuous monitoring, headwater streams are rarely monitored for nutrient status. Traditional monitoring of upland streams has relied on either manual sampling or the collection of samples from automatic samplers. Nevertheless, research has shown that upland streams are less impaired by nutrient pollution than lowland rivers, but because of their size and limited dilution capacity they are more susceptible to nutrient impairment.

References
• Bowes, M. J., Gozzard, E., Johnson, A. C., Scarlett, P. M., Roberts, C., Read, D. S., et al. (2012a). Spatial and temporal changes in chlorophyll-a concentrations in the River Thames basin, UK: are phosphorus concentrations beginning to limit phytoplankton biomass? Sci. Total Environ. 426, 45–55. doi: 10.1016/j.scitotenv. 2012.02.056
• Bowes, M. J., Ings, N. L., McCall, S. J., Warwick, A., Barrett, C., Wickham, H. D., et al. (2012b). Nutrient and light limitation of periphyton in the River Thames: implications for catchment management. Sci. Total Environ. 434, 201–212. doi: 10.1016/j.scitotenv.2011.09.082
• Dodds, W. K., Smith, V. H., and Lohman, K. (2002). Nitrogen and phosphorus relationships to benthic algal biomass in temperate streams. Can. J. Fish. Aquat Sci. 59, 865–874. doi: 10.1139/f02-063
• McCall, S. J., Bowes, M. J., Warnaars, T. A., Hale, M. S., Smith, J. T., Warwick, A., et al. (2014). Impacts of phosphorus and nitrogen enrichment on periphyton accrual in the River Rede, Northumberland, UK. Inland Waters 4, 121–132. doi: 10.5268/IW-4.2.692
• McCall, S. J., Hale, M. S., Smith, J. T., Read, D. S., and Bowes, M. J. (2017). Impacts of phosphorus concentration and light intensity on river periphyton biomass and community structure. Hydrobiologia 792, 315–330. doi: 10.1007/s10750-016-3067-1

Monitoring technology
Sampling for laboratory analysis can be a costly and time-consuming activity, particularly at upland streams in remote locations with difficult access. In addition, spot sampling reveals nutrient levels at a specific moment in time, and therefore risks missing concentration spikes. Continuous monitoring is therefore generally preferred, but in the past this has been difficult to achieve with the technology available because of its requirement for frequent re-calibration and mains power.

High resolution SRP monitoring has been made possible in almost any location with the launch by OTT Hydromet of the the ‘HydroCycle PO4’ which is a battery-powered wet chemistry analyser for the continuous analysis of SRP. Typically, the HydroCycle PO4 is deployed into the river for monitoring purposes, but recent work by the Environment Agency has deployed it in a flow-through chamber for measuring extracted water.

The HydroCycle PO4 methodology is based on US EPA standard methods, employing pre-mixed, colour coded cartridges for simple reagent replacement in the field. Weighing less than 8kg fully loaded with reagents, it is quick and easy to deploy, even in remote locations. The instrument has an internal data logger with 1 GB capacity, and in combination with telemetry, it provides operators with near real-time access to monitoring data for SRP.

The quality of the instrument’s data is underpinned by QA/QC processing in conjunction with an on-board NIST standard, delivering scientifically defensible results. Engineered to take measurements at high oxygen saturation, and with a large surface area filter for enhanced performance during sediment events, the instrument employs advanced fluidics, that are resistant to the bubbles that can plague wet chemistry sensors.

Environment Agency application
The National Laboratory Service Instrumentation team (NLSI) provides support to all high resolution water quality monitoring activities undertaken across the Agency, underpinning the EA’s statutory responsibilities such as the WFD, the Urban Waste Water Directive and Statutory Surface Water Monitoring Programmes. It also makes a significant contribution to partnership projects such as Demonstration Test Catchments and Catchments Sensitive Farming. Technical Lead Matt Loewenthal says: “We provide the Agency and commercial clients with monitoring systems and associated equipment to meet their precise needs. This includes, of course, nutrient monitoring, which is a major interest for everyone involved with water resources.”

Matt’s team has developed water quality monitoring systems that deliver high resolution remote monitoring with equipment that is quick and easy to deploy. There are two main options. The ‘green box’ is a fully instrumented cabinet that can be installed adjacent to a water resource, drawing water and passing it though a flow-through container with sensors for parameters such as Temperature Dissolved Oxygen, Ammonium, Turbidity, Conductivity pH and Chlorophyll a. Each system is fitted with telemetry so that real-time data is made instantly available to users on the cloud.

Conscious of the need to better understand the role of P in rivers, Matt’s team has integrated a HydroCycle PO4 into its monitoring systems as a development project.
Matt says: “It’s currently the only system that can be integrated with all of our remote monitoring systems. Because it’s portable, and runs on 12 volts, it has been relatively easy to integrate into our modular monitoring and telemetry systems.

“The HydroCycle PO4 measures SRP so if we need to monitor other forms of P, we will use an auto sampler or deploy a mains-powered monitor. However, monitoring SRP is important because this is the form of P that is most readily available to algae and plants.”

Explaining the advantages of high resolution P monitoring, Matt refers to a deployment on the River Dore. “The data shows background levels of 300 µg P/l, rising to 600 µg P/l following heavy rain, indicating high levels of P in run-off.”

Nitrate
Similar to phosphates, excessive nitrate levels can have a significant impact on water quality. In addition, nitrates are highly mobile and can contaminate groundwater, with serious consequences for wells and drinking water treatment. Nitrate concentrations are therefore of major interest to the EA, but traditional monitoring technology has proved inadequate for long-term monitoring because of a frequent recalibration requirement. To address this need, which exists globally, OTT Hydromet developed the SUNA V2, which is an optical nitrate sensor, providing high levels of accuracy and precision in both freshwater and seawater.

The NLSI has evaluated the SUNA V2 in well water and Matt says: “It performed well – we took grab samples for laboratory analysis and the SUNA data matched the lab data perfectly. We are therefore excited about the opportunity this presents to measure nitrate continuously, because this will inform our understanding of nitrate pollution and its sources, as well as the relationship between groundwater and surface water.”

Summary
The new capability for high-resolution monitoring of nutrients such as phosphorus will enable improved understanding of its effects on ecological status, and in turn will inform decisions on what acceptable P concentrations will be for individual rivers. This is vitally important because the cost of removing P from wastewater can be high, so the requirements and discharge limits that are placed on industrial and wastewater companies need to be science based and supported by reliable data. Similarly, nitrate pollution from fertilizer runoff, industrial activities and wastewater discharge, has been difficult to monitor effectively in the past because of the technology limitations. So, as improved monitoring equipment is developed, it will be possible to better understand the sources and effects, and thereby implement effective prevention and mitigation strategies.

@OTTHydrometry @EnvAgency @CEHScienceNews #Water #Environment

Researchers investigate ultra-low Mediterranean nutrient levels.

25/04/2018

Researchers at Haifa University’s Marine Biological Station in Israel are exploiting the ultra-low detection limits of advanced laboratory equipment to measure extremely low nutrient concentrations in marine water.

H.Nativ – Morris Kahn Marine Research Station

The University’s Prof. M. D. Krom says: “We work in the Eastern Mediterranean which has the lowest regional concentration of dissolved nutrients anywhere in the global ocean. We therefore utilize an automated segmented flow analyzer from SEAL Analytical, which has been specially adapted to accommodate ultra-low measurements.”

The SEAL AutoAnalyzer 3 (AA3) is a 4 channel system, measuring Phosphate with a long flow cell which has a detection limit of 2 nM. Ammonia is measured using a JASCO fluorometer with a similar ultra-low detection limit, and Silicate, which has a higher concentration, is measured using SEAL’s high resolution colorimetric technology.

The measurement data are being used to determine the season nutrient cycling in the system, which will then be used to help understand the nature of the food web and the effects of global environmental and climate change.

Low nutrient levels in the Mediterranean
The eastern Mediterranean Sea (EMS) has an almost unique water circulation. The surface waters (0-200m) flow into the Mediterranean through the Straits of Gibraltar and from there into the EMS at the Straits of Sicily. As the water flows towards the east it becomes increasingly saline and hence denser. When it reaches the coast of Turkey in winter it also cools and then flows back out of the Mediterranean under the surface waters to Sicily, and then eventually through the Straits of Gibraltar to the North Atlantic. This outflowing layer exists between 200m and 500m depth.

Phytoplankton grow in the surface waters (0-200m) because that is the only layer with sufficient light. This layer receives nutrients from the adjacent land, from rivers and wastewater discharges, and also from aerosols in the atmosphere. These nutrients are utilized by the plankton as they photosynthesize. When the plants die (or are eaten) their remains drop into the lower layer and are jetted out of the EMS. Because the water flows are so fast (it takes just 8 years for the entire surface layers of the EMS to be replaced), these nutrient rich intermediate waters rapidly expel nutrients from the basin. The result is very low nutrient concentrations and very low numbers of phytoplankton – some of the lowest values anywhere in the world. Prof. Krom says: “The maximum levels of nutrients measured in the EMS are 250 nM phosphate, 6 uM nitrate and 6-12 uM silicate. Ammonia is often in the low nanomolar range. By contrast, in the North Atlantic, values are 1000 nM phosphate, 16 uM nitrate and 20 uM silicate, and the levels in the North Pacific are even higher.”

The value of data
The low levels of plankton caused by low nutrient levels, result in a low biomass of fish. Nevertheless, coastal areas generally support more fish than offshore, so the research will seek to quantify and understand the nutrient cycle in the coastal regions, which is poorly understood at present. “We plan to develop understandings which will inform stakeholders such as government. For example, there is a discussion about the potential for fish farms off the Israeli coast, so our work will enable science-based decisions regarding the quantity of fish that the system can support.”

To-date, three data sets have been taken from the EMS, and the first publishable paper is in the process of being prepared.

Choosing the right analyzer
Prof. Krom says that his first ‘real’ job was working for the (then) Water Research Centre at Medmenham in Britain, where he was involved in the development of chemical applications for the Technicon AA-II autoanalyzers, which included going on secondment to Technicon for several months. SEAL Analytical now own and manufacture the AutoAnalyzer brand of Continuous Segmented Flow Analyzers, so his career has been connected with autoanalyzers for decades. For example his is Professor (Emeritus) at the University of Leeds (GB), where, again, he worked with SEAL autanalyzers. An AA3 instrument was employed at Leeds in a project to investigate the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans.

Explaining the reasoning behind the purchase of a new AA3 at Haifa University, Prof. Krom says: “During a research cruise, it is necessary to analyse samples within a day to avoid changes in concentration due to preservation procedures.

“Typically we analyse 50-80 samples per day, so it is useful to useful to be able to analyze large numbers of samples automatically. However, the main reasons for choosing the SEAL AA3 were the precision, accuracy and low limits of detection that it provides.”

Commenting on this application for SEAL’s analyzers, company President Stuart Smith says: “Many of our customers analyze nutrient levels in freshwater and marine water samples, where high levels of nutrients are a concern because of increasing levels of algal blooms and eutrophication. However, Prof. Krom’s work is very interesting because, in contrast, he is looking at extremely low levels, so it is very gratifying that our instruments are able to operate at both ends of the nutrient concentration spectrum.

Bibliography
• Powley, H.R., Krom, M.D., and Van Cappellen, P. (2017) Understanding the unique biogeochemistry of the Mediterranean Sea: Insights from a coupled phosphorus and nitrogen model. Global Biogeochemical Cycles, 11; 1010-1031. DOI 10.1002/2017GB005648.

• Stockdale, A. Krom, M. D., Mortimer, R.J.G., Benning, L.G., Carslaw, K.S., Herbert, R.J., Shi, Z., Myriokefalitakis, S., Kanakidou, M., and Nenes, A., (2016) Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans. PNAS vol. 113 no. 51

#SealAnal #Marine @_Enviro_News

Train derailment prompts contaminated land investigation.

11/01/2018

A train derailment in Mississippi resulted in ground contamination by large quantities of hazardous chemicals, and environmental investigators have deployed sophisticated on-site analytical technology to determine the extent of the problem and to help formulate an effective remediation strategy. Here Jim Cornish from Gasmet Technologies discusses this investigation.

Jim Cornish

On March 30th 2015 a long freight train, transporting a variety of goods including lumber and chemicals, wound its way through the state of Mississippi (USA). At around 5pm, part of the train failed to negotiate a curved portion of the track in a rural area near Minter City, resulting in the derailment of nine railcars, one of which leaked chemicals onto agricultural farmland and woodlands. Emergency response and initial remediation activities were undertaken, but the remainder of this article will describe an environmental investigation that was subsequently conducted by Hazclean Environmental Consultants using a portable multiparameter FTIR gas analyzer from Gasmet Technologies.

Background
Over 17,000 gallons of Resin Oil Heavies were released from the railcar, and the main constituent of this material is dicyclopentadiene (DCPD). However, in addition to DCPD, Resin Oil Heavies also contains a cocktail of other hydrocarbons including ethylbenzene, indene, naphthalene, alpha-methyl styrene, styrene, vinyl toluene, 1, 2, 3-trimenthylbenzene, 1, 2, 4-trimethylbenzene, 1, 3, 5-trimethylbenzene and xylenes.

DCPD is highly flammable and harmful if swallowed and by inhalation. Its camphor-like odor may induce headaches and symptoms of nausea, and as a liquid or vapor, DCPD can be irritating to the eyes, skin, nose, throat or respiratory system. DCPD is not listed as a carcinogen, however DCPD products may contain benzene, which is listed as a human carcinogen. DCPD is not inherently biodegradable, and is toxic to aquatic organisms with the potential to bioaccumulate.

It is a colorless, waxy, flammable solid or liquid, used in many products, ranging from high quality optical lenses through to flame retardants for plastics and hot melt adhesives. As a chemical intermediate it is used in insecticides, as a hardener and dryer in linseed and soybean oil, and in the production of elastomers, metallocenes, resins, varnishes, and paints. DCPD-containing products are also used in the production of hydrocarbon resins and unsaturated polyester resins.

Emergency Response
Emergency response phase activities were performed from March 31 through May 2, 2015. Response objectives and goals were formally documented by utilizing Incident Action Plans for each operational period. Activities between April 11 and April 28, 2015 were summarized in weekly reports and submitted to the Mississippi Department of Environmental Quality (MDEQ) and the Environmental Protection Agency (EPA).

Approximately 10,189 gallons of the leaked product was recovered, leaving 5,458 gallons to contaminate the farmland surface and subsurface soil, surface waters, groundwater and ambient air. The site contamination problem was exacerbated due to heavy rainfall and associated stormwater runoff which caused the unrecovered product to migrate from the spill site.

Taking account of the high rainfalls levels that followed the event, it was calculated that contaminated stormwater runoff from the immediate project site (10 acres with 8.7 inches of rainfall) was 2,362,485 gallons less that retained by emergency retention berms. Approximately 207,000 gallons of contaminated stormwater were collected during the emergency response, in addition to approximately 7,870 tons of impacted material which were excavated for disposal. Following removal of the gross impacted material, the site was transferred into Operation and Maintenance status, conducted in accordance with a plan approved by MDEQ.

Ongoing site contamination
Groundwater and soil samples were collected and analyzed in 2015 and 2016, producing analytical data which confirmed that widespread soil and groundwater contamination still existed at the site. Further remediation was undertaken, but the landowners were extremely concerned about the fate of residual chemicals and contracted Hazclean Environmental Consultants to conduct a further investigation.

“The affected land is used for agricultural purposes, producing crops such as soybeans and corn,” says Hazclean President, E. Corbin McGriff, Ph.D., P.E. “Consequently, there were fears that agricultural productivity would be adversely affected and that chemicals of concern might enter the food chain.
“This situation was exacerbated by the fact that the landowners could still smell the contamination and initial investigation with PID gas detectors indicated the presence of volatile organic compounds (VOCs).”

Hazclean’s Joseph Drapala, CIH, managed and conducted much of the site investigation work. He says: “While PID gas detectors are useful indicators of organic gases, they do not offer the opportunity to quantify or speciate different compounds, so we spoke with Jeremy Sheppard, the local representative of Gasmet Technologies, a manufacturer of portable FTIR (Fourier Transform Infrared) gas analyzers.

Soil Vapor Analysis with FTIR

“Jeremy explained the capabilities of a portable, battery-powered version of the Gasmet FTIR gas analyzer, the DX4040, which is able to analyze up to 25 gases simultaneously, producing both qualitative and quantitative measurements. Gasmet was therefore contacted to determine whether this instrument would be suitable for the Mississippi train spill application.

“In response, Gasmet confirmed that the DX4040 would be capable of measuring the target species and offered to create a specific calibration so that these compounds could be analyzed simultaneously on-site.”

Site investigation with FTIR analysis
A sampling zone was defined to capture potential contamination, and measurements were taken for surface and subsurface soil, groundwater, and surface and subsurface air for a range of VOCs.

Vapor Well

The area-wide plan resulted in the installation of four permanent monitoring wells for groundwater sampling, twenty vapor monitoring wells, and twenty test borings for field screening. The test borings indicated the presence of VOCs which were further characterized by sampling specific soil sections extracted from the parent core.

In addition to the almost instantaneous, simultaneous measurement of the target compounds, the Gasmet DX4040 stores sample spectra, so that post-measurement analyses can be undertaken on a PC running Gasmet’s Calcmet™ Pro software, providing analytical capability from a library of 250 compounds. “The Gasmet DX4040 was manufacturer-calibrated for dicyclopentadiene, benzene, ethylbenzene, naphthalene, styrene, toluene, 1,2,3-trimenthylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene and m, o, and p and total xylenes at a detection range of 0.01 ppm to 100 ppm in air,” Joseph reports, adding: “The ability to compare recorded spectra with the Calcmet Pro library is a major advantage because it enables the measurement of unknown compounds.”

The operating procedures for the DX4040 indicate a simple, convenient requirement for daily calibration with zero gas prior to each monitoring activity. However, in addition to the use of nitrogen as the zero gas, Joseph also employed specialty gas (DCPD) certified for 1 ppm and 5 ppm as a calibration check and a response (akin to bump testing) gas.

Site screening
The test borings provided soil samples that were vapor-tested on-site as part of the screening process. Vapor from the extracted soil samples was analyzed by placing the soil samples in vessels at ambient temperature and connecting the DX4040 in a closed loop from the vessel, so that air samples could be continually pumped from the vessel to the analyzer and returned to the vessel. This screening activity helped to determine the location for vapor wells.

All soil samples were screened with the DX4040 and those with the highest reading from each boring were sent for laboratory analysis.

Vapor wells were fitted with slotted PVC liners and capped. Before monitoring, the cap was replaced with a cap containing two ports to enable the DX4040 to be connected in a similar closed-loop monitoring system to that which was employed for the soil samples.

Conclusions
As a result of this investigation it was possible for Hazclean to determine that the release of DCPD in the vapor state, as measured in the vapor monitor wells, is a result of surface and subsurface contamination in the soil and groundwater, and that this contamination will remain in the future.

Vapor analysis data provided by the DX4040 identified DCPD, benzene, styrene and xylene previously adsorbed on soil and/or wetted surfaces undergoing diffusion and evaporation. The adsorption, diffusion and evaporation of DCPD et al. released and spread across the farmland is a mechanism to explain the vapor concentrations found in vapor monitor wells as well as the ambient malodor problem.

The long term release of DCPD and other VOCs will continue to occur in the impact area unless a larger remediation project is conducted to remove soil and groundwater contamination. Furthermore, Hazclean recommends that, as a result of the effectiveness of the Gasmet DX4040 in this investigation, the same technology should be employed in any subsequent screening activities, using the same Gasmet calibration configuration.

Summarizing, Joseph Drapala says: “The Gasmet DX4040 was an essential tool in this investigation. Screening activities should have the ability to detect and identify the target compounds, as well as any secondary compounds that may have already been present on-site or could have been produced as a result of chemical interactions.
“As an FTIR gas analyzer, the DX4040 meets these requirements, providing enormous analytical capability through Gasmet’s Calcmet software. However, the instrument is also small, lightweight and battery powered which makes it ideal for field investigations.”


Measuring CO2 to optimise bulk storage of food.

24/07/2017

Meeting the food requirements of a growing global population is becoming increasingly difficult. Despite the need for additional food, it is estimated that 50-60% of grain is lost after harvesting, at a cost of about $1 trillion per year. (See note 1 below)

One of the major reasons for lost grain is spoilage due to mould or insect infestation during storage.2 To provide a constant supply of grain year-round, after grains are harvested they are often kept in long term storage. Maintaining the quality of stored grain is crucial, both to ensure the quality of the final food products, and to prevent economic losses for farmers.

Edinburgh Sensors GascardNG Sensor

Insects and moulds can grow in stored grain, and their ability to flourish depends on the temperature and moisture of the stored grain. Moulds are the most common cause of grain spoilage and can cause changes in the appearance and quality of stored grains. Some moulds can release toxic chemicals called mycotoxins which can suppress the immune system, reduce nutrient absorption, cause cancer, and even be lethal in high doses. It is therefore crucially important to prevent the presence of mycotoxins in food products.2

Monitoring Stored Grain
Farmers are advised to check their stored grain weekly for signs of spoilage.3 Traditionally, grains are checked visually and by odour. Grain sampling can allow earlier detection of insects and moulds, but these methods can be tedious and time-consuming. Rapid, simple methods are needed for early detection of spoilage and to prevent grain losses.2

When moulds and insects grow, and respire, they produce CO2, moisture and heat. Temperature sensors detect increases in temperature caused by mould growth or insect infestation, therefore indicating the presence of grain spoilage. However, they are not able to detect temperature increases caused by infestation unless the infestation is within a few meters of the sensors. CO2 sensors can detect the CO2 produced by moulds and insects during respiration. As the CO2 gas moves with air currents, CO2 sensors can detect infestations that are located further away from the sensor than temperature sensors. CO2 measurements are therefore an important part of the toolkit needed to monitor stored grain quality.2

Using CO2 Measurements to Detect Spoilage
CO2 monitoring can be used for early detection of spoilage in stored grains, and to monitor the quality of stored grains. Safe grain storage usually results in CO2 concentrations below 600 ppm, while concentrations of 600-1500 ppm indicate the onset of mould growth. CO2 concentrations above 1500 ppm indicate severe infestations and could represent the presence of mycotoxins.4

CO2 measurements can be taken easily, quickly and can detect infestations 3-5 weeks earlier than temperature monitoring. Once spoilage is detected, the manager of the storage facility can address the problem by aerating, turning, or selling the grain. Furthermore, CO2 measurements can aid in deciding which storage structure should be unloaded first.2

Research published by Purdue University and Kansas State University have confirmed that high CO2 levels detected by stationary and portable devices are associated with high levels of spoilage and the presence of mycotoxins.4,5 Furthermore, they compared the ability of temperature sensors and CO2 sensors in a storage unit filled with grain to detect the presence of a simulated ‘hot spot’ created using a water drip to encourage mould growth.

The CO2 concentration in the headspace of the storage unit showed a strong correlation with the temperature at the core of the hot spot, and the CO2 sensors were, therefore, able to detect biological activity. The temperature sensors were not able to detect the mould growth, despite being placed within 0.3-1 m of the hotspot.6

To enable efficient monitoring of grain spoilage accurate, reliable and simple to use CO2 detectors are required. Gascard NG Gas Detector from Edinburgh Sensors provide accurate CO2 measurements along with atmospheric data, enabling grain storage managers to make decisions with confidence.

The Gascard NG Gas Detector uses a proprietary dual wavelength infrared sensor to enable the long term, reliable measurement of CO2 over a wide range of concentrations and in temperatures ranging from 0-45 °C. Measurements are unaffected by humidity (0-95% relative humidity) and the onboard pressure and temperature sensors provide real-time environmental compensation, resulting in the most accurate CO2 concentration readings.

Conclusion
Easy, fast, and accurate CO2 concentration monitoring during grain storage can provide early detection of grain spoilage, resulting in reduced grain losses, higher quality stored grain, and lower mycotoxin levels. CO2 monitoring could save millions of dollars annually in the grain production industry.4


References

  1. Kumar D, Kalita P, Reducing Postharvest Losses during Storage of Grain Crops to Strengthen Food Security in Developing Countries. Foods 6(1):8, 2017.
  2. http://www.world-grain.com/Departments/Grain-Operations/2016/7/Monitoring-CO2-in-stored-grain.aspx?cck=1 Accessed May 25th, 2017.
  3. HGCA Grain storage guide for cereals and oilseeds, third edition, available from: https://cereals.ahdb.org.uk/media/490264/g52-grain-storage-guide-3rd-edition.pdf Accessed May 25th, 2017.
  4. Maier DE, Channaiah LH, Martinez-Kawas, A, Lawrence JS, Chaves EV, Coradi PC, Fromme GA, Monitoring carbon dioxide concentration for early detection of spoilage in stored grain. Proceedings of the 10th International Working Conference on Stored Product Protection, 425, 2010.
  5. Maier DE, Hulasare R, Qian B, Armstrong P, Monitoring carbon dioxide levels for early detection of spoilage and pests in stored grain. Proceedings of the 9th International Working Conference on Stored Product Protection PS10-6160, 2006.
  6. Ileleji KE, Maier DE, Bhat C, Woloshuk CP, Detection of a Developing Hot Spot in Stored Corn with a CO2 Sensor. Applied Engineering in Agriculture 22(2):275-289, 2006.

 


The ‘ins and outs’ of air quality monitoring!

20/02/2017
The British National Institute for Health and Care Excellence (NICE) recently issued draft guidance on ‘Air pollution – outdoor air quality and health.’ 

Here, Jim Mills, Managing Director of Air Monitors Ltd, explains why there will need to be more funding for monitoring if the mitigation measures mentioned in the guidance are to be implemented effectively. Jim also highlights the close relationship between outdoor air quality and the (often ignored) problems with indoor air quality.

The NICE guidelines are being developed for Local Authority staff working in: transport, planning, air quality management and public health. The guidance is also relevant for staff in healthcare, employers, education professionals and the general public.

Covering road-traffic-related air pollution and its links to ill health, the guidelines aim to improve air quality and so prevent a range of health conditions and deaths. Unfortunately, on the day that the draft guideline was published, most of the national media focused on one relatively minor recommendation relating to speed bumps. ‘Where physical measures are needed to reduce speed, such as humps and bumps, ensure they are designed to minimise sharp decelerations and consequent accelerations.’ Measures to encourage ‘smooth driving’ are outlined; however, the guidelines also address a wide range of other issues, which, in combination, would help tackle urban air pollution.

Public sector transport services should implement measures to reduce emissions, but this is an area that could involve the greatest financial cost.

Many local authorities would doubtless comment that they are already implementing many of the guideline recommendations, but refer to budgetary constraints on issues that involve upfront costs. This issue was raised on BBC Radio 4 when the issue was discussed on 1st December.

AQMesh Pod

AQMesh Pod

The NICE guidelines recommend the inclusion of air quality issues in new developments to ensure that facilities such as schools, nurseries and retirement homes are located in areas where pollution levels will be low. LAs are also urged to consider ways to mitigate road-traffic-related air pollution and consider using the Community Infrastructure Levy for air quality monitoring. There are also calls for information on air quality to be made more readily available.

LAs are also being urged to consider introducing clean air zones including progressive targets to reduce pollutant levels below the EU limits, and where traffic congestion contributes to poor air quality, consideration should be given to a congestion charging zone. The guidelines also highlight the importance of monitoring to measure the effects of these initiatives.

As part of the consultation process, NICE is looking for evidence of successful measures and specifically rules out “studies which rely exclusively on modelling.”

In summary, all of the initiatives referred to in the NICE report necessitate monitoring in order to be able to measure their effectiveness. However, most LAs do not currently possess the monitoring capability to do so. This is because localised monitoring would be necessary before and after the implementation of any initiative. Such monitoring would need to be continuous, accurate and web-enabled so that air pollution can be monitored in real-time. AQMesh is therefore the ideal solution; small, lightweight, quick and easy to install, these air quality monitors are able to monitor all the main pollutants, including particulates, simultaneously, delivering accurate data wirelessly via the internet.

Whilst AQMesh ‘pods’ are very significantly lower in cost both to buy and to run than traditional reference stations, they still represent a ‘new’ cost. However any additional costs are trivial in comparison with the costs associated with the adverse health effects caused by poor air quality, as evidenced in the recent report from the Royal College of Physicians.

Inside Out or Outside In?

Fidas® Frog

Fidas® Frog

The effects of air pollution are finally becoming better known, but almost all of the publicity focuses on outdoor air pollution. In contrast, indoor air quality is rarely in the media, except following occasional cases of Carbon Monoxide poisoning or when ‘worker lethargy’ or ‘sick building syndrome’ are addressed. However, it is important to understand the relationship between outdoor air quality and indoor air quality. Air Monitors is currently involved in a number of projects in which air quality monitoring is being undertaken both outside and inside large buildings, and the results have been extremely interesting.

Poorly ventilated offices tend to suffer from increased Carbon Dioxide as the working day progresses, leading to worker lethargy. In many cases HVAC systems bring in ‘fresh’ air to address this issue, but if that fresh air is in a town or city, it is likely to be polluted – possibly from particulates if it is not sufficiently filtered and most likely from Nitrogen Dioxide. Ventilating with outdoor air from street level is most likely to bring air pollution into the office, so many inlets are located at roof level. However, data from recent studies indicate that the height of the best air quality can vary according to the weather conditions, so it is necessary to utilise a ‘smart’ system that monitors air quality at different levels outside the building, whilst also monitoring at a variety of locations inside the building. Real-time data from a smart monitoring network then informs the HVAC control system, which should have the ability to draw air from different inlets if available and to decide on ventilation rates depending on the prevailing air quality at the inlets. This allows the optimisation of the internal CO2, temperature and humidity whilst minimising the amount of external pollutants brought into the indoor space. In circumstances where the outside air may be too polluted to be used to ventilate, it can be pre-cleaned by scrubbing the pollutant gases in the air handling system before being introduced inside the building.

Fidas200The implementation of smart monitoring and control systems for buildings is now possible thanks to advances in communications and monitoring technology. AQMesh pods can be quickly and easily installed at various heights outside buildings and further units can be deployed internally; all feeding near-live data to a central control system.

Another example of indoor air quality monitoring instrumentation developing from outdoor technology is the ‘Fidas Frog,’ a new fine dust aerosol spectrometer developed by the German company Palas. The Frog is an indoor, wireless, battery-powered version of the hugely popular, TÜV and MCERTS certified Fidas 200. Both instruments provide simultaneous determination of PM fractions, particle number and particle size distribution, including the particle size ranges PM1, PM2.5, PM4, PM10 and TSP.

Evidence of outdoor air pollution contaminating indoor air can be obtained with the latest Black Carbon monitors that can distinguish between the different optical signatures of combustion sources such as diesel, biomass, and tobacco. The new microAeth® MA200 for example, is a compact, real-time, wearable (400g) Black Carbon monitor with built-in pump, flow control, data storage, and battery with onboard GPS and satellite time synchronisation. Samples are collected on an internal filter tape and wireless communications are provided for network or smartphone app integration and connection to other wireless sensors. The MA200 is able to monitor continuously for 2-3 weeks. Alternatively, with a greater battery capacity, the MA300 is able to provide 3-12 months of continuous measurements.

In summary, a complete picture of indoor air quality can be delivered by a combination of AQMesh for gases, the Palas Frog for particulates and the microAeth instruments for Black Carbon. All of these instruments are compact, battery-powered, and operate wirelessly, but most importantly, they provide both air quality data AND information on the likely source of any contamination, so that the indoor effects of outdoor pollution can be attributed correctly.

@airmonitors #Environment #PAuto @_Enviro_News


Analyzer underpins growth of container inspection company.

10/02/2017

After a career as a customs officer in the Netherlands, Wim van Tienen was well aware of the toxic gas hazards presented by some freight containers, so in 2009 he started a company, Van Tienen Milieuadvies B.V., offering gas analysis and safety advice. The company grew quickly and now employs 23 staff. Wim attributes a large part of this success to the advanced FTIR gas detection and analysis technology upon which the company’s services depend.

Background

Wim van Tienen

Wim van Tienen

It has been estimated that there are more than 17 million shipping containers in the world, and at any time about one third of them are on ships, trucks, and trains. Over a single year, the total number of container trips has been estimated to be around 200 million.

The air quality inside containers varies enormously, depending on the goods, the packing materials, transit time, temperature, humidity and the possible presence of fumigants. Consequently, many containers contain dangerous levels of toxic gases and represent a major threat to port and transport workers, customs officials, warehousemen, store employees and consumers. It is therefore essential that risks are assessed effectively before entry is permitted.

Solvent vapours and most fumigants, whilst harmful, can be detected by the human nose, but Wim says: “Some gases are odourless and some have a high odour detection threshold, which means that you can only smell the substance in high concentrations; ethylene oxide for example, is commonly used as a sterilant in relation to medical devices. It is extremely toxic and has a low TLV limit of 0,5 ppm. However the odour threshold limit of ethylene oxide is 500 ppm, so detection with instrumentation is essential.”

The wide variety of potential contaminants represents a technological challenge to those responsible for testing, because if testers seek to detect specific gases, they risk failing to detect other compounds. It is also not practical to test every single container, so logical procedures must be established in order to minimise risks.

Gas Detection and Measurement
In 2009, when Wim first established the company, container gas detection was carried out with traditional field measurement techniques (gas detection sensors and tubes). “This approach was complicated, costly and time-consuming, and it was impossible to cover all risks,” he says. “With sensors and tubes, only a limited number of compounds can be measured specifically. Furthermore, the accuracy of detection tubes is poor and they can suffer from cross-sensitive reactions by interfering substances.

“Technologies such as PID-detectors respond to a wide variety of organic compounds, but they are not selective and unable to detect commonly found substances with high ionisation potentials such as 1,2-dichloroethane and formaldehyde.” Wim does not, therefore, believe that traditional measurement techniques are the best approach for covering all risks. “In order to test for the most common gases, it would be necessary to utilise a large number of tubes for every container, but this would still risk failing to detect other compounds and would be very expensive.

“It is possible to speciate organic compounds when using a Gas Chromatograph, but the number of compounds that can be tested is limited, and the use of a GC necessitates frequent calibration with expensive standard gases.”

Simultaneous multigas analysis
As a result of the problems associated with traditional gas detection techniques, Wim was keen to find an alternative technology and in 2013 he became aware of portable FTIR multigas analyzers from the Finnish company Gasmet Technologies. “The Gasmet DX4040 appeared to be the answer to our prayers,” Wim says. “The instrument is able to both detect and measure hundreds of compounds simultaneously; with this technique all inventoried high risk substances, such as ethylene oxide and formaldehyde, are always measured in real-time.

“With the help of Peter Broersma from Gasmet’s distributor Reaktie, a special library of over 300 gases was developed for our container monitoring application, and 8 Gasmet DX4040 FTIR instruments are now employed by our team of gas testing specialists.”

The major advantage of the Gasmet FTIR analyzers is the simultaneous multigas analysis capability. However Wim says: “Our testing work is now much faster, efficient and cost-effective, not least because the analyzers are small, lightweight, relatively simple to run, and no calibration is required other than a quick daily zero check with Nitrogen.”

Van Tienen Milieuadvies also employs a fully trained and highly qualified chemist, Tim Gielen, who is able to conduct in-depth analysis of recorded FTIR spectra when necessary. This may involve comparing results with Nist reference spectra for over 5000 compounds.

Most of the gases that are detected and measured by FTIR analyzers are cargo related. Wim says: “Off-gassing during shipment is the greatest problem, producing VOCs such as Toluene, Xylenes, MEK, 1,2 dichloroethane, blowing agents such as isopentane, and butanes from the packing materials and products.

“Formaldehyde, which evaporates from glued pallets, is most commonly found. On the other hand, less frequently found fumigants, such as sulfuryl difluoride and hydrogen cyanide are also always monitored with our FTIR analyzers.”

Container management
The need for container gas testing is driven by employers’ duty of care for employees, which is embedded in international health and safety regulations. Companies receiving containers must investigate whether employees that open or enter containers, may be exposed to the dangers of suffocation, intoxication, poisoning, fire or explosion. In order for employers to protect staff from these hazards, a risk assessment is necessary, coupled with an effective plan to categorise and monitor container flows. “This is how we develop an effective testing strategy,” Wim explains. “If a flow of containers from the same source containing the same goods and packing materials is found to be safe, the number of containers being tested within that flow can be reduced. Similarly, if toxic gases are identified regularly in a container flow, the frequency of testing will be increased.”

Once a container has been found to contain toxic levels of a gas or gases, it is necessary for that container to be ‘de-gassed’ which is a service that Van Tienen Milieuadvies provides. The process involves fitting a powerful ventilator to the door and capturing the gases with activated carbon. Once degassing is complete, it is important that the container is unloaded promptly, because the gases involved will re-accumulate quickly in a closed container, resulting in the need for repeat testing.

With the benefit of many years of experience, Wim estimates that around 10% of containers contain toxic gases. “This means that hundreds of thousands of containers are travelling the world, representing a major risk to anyone that might enter or open them, so it is vital that effective testing strategies are in place wherever that risk exists.”

“FTIR gas analysis has benefited this work enormously. For us, the main advantages are speed and peace of mind – we are now able to test more containers per day, and by testing for such a large number of target compounds, we are able to dramatically lower the risks to staff. The speed with which we are now able to test containers, coupled with the negligible requirement for service, calibration and consumables, means that the ongoing cost of monitoring is minimal.

“Van Tienen combines the Gasmet DX4040 measurements with risk analysis, which provides the best protection for staff responsible for opening containers. We have LRQA certification for the procedures that we have developed to demonstrate compliance with occupational health and safety legislation.

“Risk analysis provides cost reduction for our clients, due to the fact that measurement frequencies in safe flows can be reduced significantly. Root cause analysis is also part of our risk analysis.”

Looking forward Wim believes that the use of Gasmet FTIR will expand rapidly around the world as the risks associated with containers become better understood, and as employers become more aware of the advantages of the technology.