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

Long-term seawater analysis, using Seal Analyser, has global significance

28/01/2013

Most of Europe has, and indeed many places not that used to arctic weather conditions in North America have, been shivering and digging out during the month of January so a story from more sunny climes is more than welcome.

This study tells of the University of Hawaii collecting deep sea water samples to monitor subtle long-term changes in the ocean surrounding Hawaii. To get you in the mood we appropriated this photo.

Stockphoto

Stockphoto

Since 1988, scientists from the University of Hawaii have been conducting almost monthly deep-sea research expeditions to collect water samples for subsequent laboratory analysis. Originally designed to characterise subtle long-term changes in environments that were believed to be stable, the work has revealed some surprising conclusions. For example, it has become evident that even in these quasi-stable ocean systems, gradual environmental change can often result in abrupt shifts from the equilibrium state.

SEAL_AA3An important part of the work involves the collection of nutrient samples to a depth of 4800 metres. These are then frozen for subsequent analysis in the University’s laboratory with a high precision SEAL Analytical AutoAnalyzer 3 (AA3) Segmented Flow Analyzer.

The sampling site is known as ‘Station ALOHA’, a Long-Term Oligotrophic Habitat Assessment located 100 km north of Oahu, Hawaii as part of the Hawaii Ocean Time-series program (HOT), which is based out of the School of Ocean and Earth Science and Technology (SOEST) and receives funding from the U.S. National Science Foundation.

The importance of long-term observations
The HOT program provides an unprecedented historical context for refining our understanding of the often subtle linkages between ocean-climate and marine biogeochemistry. Without these time-series observations, many of the processes controlling biogeochemical cycles in the deep ocean would remain obscured by the inherent complexity of the oceanic habitat.

Systematic, long-term time-series studies of selected aquatic and terrestrial habitats have yielded significant contributions to earth and ocean sciences through the characterization of climate trends. Important examples include the recognition of acid rain, the documentation of increasing carbon dioxide (CO2) in the earth’s atmosphere and the description of large scale ocean-atmosphere climate interactions in the equatorial Pacific Ocean.

Long time-series observations of climate-relevant variables in the ocean are extremely important because repeated oceanographic measurements are required to gain an understanding of natural processes or phenomena that exhibit slow or irregular change, as well as rapid event-driven variations that are impossible to document reliably from a single field expedition. Time-series studies are also ideally suited for the documentation of complex natural phenomena that are under the combined influence of physical, chemical and biological controls.

This is a CTD, an electronic instrument commonly used by oceanographers that continuously records salinity by measuring conductivity, temperature, & depth as the instrument is lowered on a hydrowire from a ship.

This is a CTD, an electronic instrument commonly used by oceanographers that continuously records salinity by measuring conductivity, temperature, & depth as the instrument is lowered on a hydrowire from a ship.

The oceans are known to play a central role in regulating the global concentration of CO2 in the atmosphere and it is generally believed that the world ocean has removed a significant portion of anthropogenic atmospheric CO2. It is clear therefore that a better understanding of the interactions between the atmosphere and the ocean is essential if we are to make informed decisions about how to protect the environment.

Seawater analysis
Measurements of water column chemistry, currents, optical properties, primary production, plankton community structure, and rates of particle export are made on each cruise and both inorganic and organic nutrient samples are analyzed to provide a clear picture of the water column.

The SEAL Analytical AA3 analyzer is capable of analyzing up to 300 tests per hour. Susan Curless has acted as the lead nutrient analyst for the HOT program from January 2005 and has employed the AA3 for nutrient analysis since that time. Susan is also one of the chief scientists of the HOT program, so when she is not out at sea organising, planning, and leading research cruises, she is in the laboratory analyzing nutrient samples.

Susan also utilizes the AA3 for nutrient samples collected on CMORE (Center for Microbial Oceanography: Research and Education) cruises.

Speaking on behalf of SEAL Analytical, Stuart Smith says: “A great deal of time, effort and money goes in to the creation of seawater samples in the HOT program. Furthermore, the data that these samples provide is of global significance, so it is hardly surprising that the program chose a high performance instrument with a reputation as the world’s most reliable segmented flow analyser.

“Leading seawater laboratory and research institutes use the SEAL AutoAnalyzer 3 and QuAAtro instruments because as well as being reliable laboratory instruments, these analyzers are designed to provide high resolution analysis despite tough conditions onboard an oceangoing research vessel, and are in routine ship-board use from the Arctic Ocean to the Weddel Sea.”

hawaii-map


Water quality is top priority at Brighton aquarium

18/06/2012

The SEA LIFE Centre next to the pier in Brighton (GB) is the world’s oldest operating aquarium. Originally designed by Eugenius Birch in 1872, the popular attraction has recently benefited from substantial renovation and now offers a range of new attractions including a Jellyfish Discovery & a Behind the Scenes tour.

With hundreds of highly valuable marine creatures to protect, water quality is a key issue and routine monitoring is now undertaken with Hach Lange instruments. Displays Curator Carey Duckhouse says “The recent building work presented a series of challenges, but we have been able to protect water quality throughout the project with a monitoring regime that was designed to quickly detect any deterioration in water quality and to provide the highest level of vigilance for the most sensitive species.”

In order to protect water quality, each tank at the Brighton attraction has its own filtration system, including a pressurised sand filter, a biological filter and a carbon filter where appropriate. Some tanks, containing particularly sensitive species such as seahorses, octopus and jellyfish, also feature an ultraviolet treatment system.

Many marine organisms will die quickly if the dissolved oxygen (DO), temperature or salinity levels move outside of acceptable boundaries, so temperature measurements are taken daily on all tanks, DO is measured three times/day in the main ocean tank, and salinity and DO are measured twice per week in all tanks. A hand-held ‘HQD’ water quality meter is employed for this purpose, utilising the latest sensor technology such as an optical LDO™ sensor which substantially improves the reliability of oxygen measurements. However, as Carey explains “Even subtle changes in water quality can stress marine organisms, which makes them more sensitive to disease, so a range of other parameters such as ammonia, nitrate, nitrite, phosphate, copper and iron, are also measured with a Hach Lange DR 2800 spectrophotometer.”

Reagents for the spectrophotometer tests are supplied in small pre-filled powder pillows containing extremely accurate amounts of reagents. This ensures that the tests are conducted in the same way every time and avoids potential errors whilst also saving time and chemical wastage.

The spectrophotometer has an internal memory containing the calibration data for a large number of parameters so that Carey and her colleagues simply choose the pillow reagents for the tests they need.

The test procedure is very simple; the contents of a powered pillow are simply added to a small sample and a coloured solution is allowed to develop for a specific time. The sample tube is then inserted into the spectrophotometer which provides a highly accurate and repeatable reading.

The water quality monitoring equipment is also used in research conducted in collaboration with Sussex University. Much of this work is with Cephalopods such as cuttle fish and addresses a range of issues including feeding behaviour, camouflage and nutrition. Accurate water quality monitoring is necessary in all of this work to ensure that observed effects are not the result of water quality changes. Visitors to the aquarium can view research work during the ‘Behind the Scenes’ tour, in addition to the nursery area, the laboratory and the food preparation section.

Clearly, water quality is key to the success of an aquarium and Carey says “If Eugenius Birch was alive today I am sure he would be delighted to see that the aquarium has continued to thrive, and as an engineer he would be fascinated by the water quality monitoring technology that we are now able to employ.”

Pictures: Julia Claxton 2012


Three men in a boat! Industrial computors as HMI for giant ship engines!

13/04/2012
Quality requirements drive MAN Diesel & Turbo

A large proportion of all ships plying the oceans are propelled by MAN Diesel & Turbo. With around 12,500 employees, the company is the leading supplier of two- and four-stroke engines for maritime use and for installation in power stations, for example.

In recent years, demand for electronically controlled B&W two-stroke diesels has risen sharply. Advanced control systems that manage fuel injection and compression contribute to better fuel economy and reduced emissions.

Special requirements at sea
With the progressive tightening of environmental requirements, ship owners are also increasingly interested in installing electronic control in existing vessels. As a bonus, modern control systems also facilitate operation and maintenance by the crew, including lubrication of the engines.
At sea, reliability takes the highest priority. Downtime costs big money. To prevent and avoid problems, the engine control system consists entirely of carefully selected, high-quality electronic components such as computers. Vital functions are also duplicated.

Since the summer of 2011, robust industrial computers from Beijer Electronics have been used in the onboard systems. In the first six months or so since deliveries started, around 150 computers from the EPC series have been commissioned, “Without a single complaint,” stresses Kennet Palm, Head of Hardware Development at MAN Diesel & Turbo, who is responsible for all the hardware used in the control electronics.

Industrial computers for tough jobs
These EPC boxes are specially designed and made for maximum reliability in the most demanding environments. Private PC buyers are mainly concerned with performance and low price. The occasional ‘blue screen’ may be irritating, but it is not a major problem. It is quite different at sea – particularly on a big tanker or freighter hundreds or even thousands of miles from port.
When MAN Diesel & Turbo chooses components for its electronic control systems, reliability combined with a long service life is crucial. “We build engines with a lifetime of 30 years, which have to work day in, day out in a tough maritime environment with all that this implies in terms of heat, humidity and vibration,” explains Palm, emphasising that factors like purchase cost and warranties are not irrelevant either.

A secure supply of products and spare parts, with ‘just in time’ delivery, is just as high on the list as quality, “to guarantee the supply of components, we made a decision at the group level to have two, or preferably three, alternative sources for every key product that we need.” Kennet Palm and his colleagues leave no stone unturned in their constant efforts to identify the best and most reliable products on the market. They search the world for computers, screens and other hardware for the control system.

Thomas Lehnemann, Kennet Palm and Niels Torres Engel at MAN Diesel & Turbo put reliability at the top of their list. “A ‘blue screen’ at sea simply isn’t an option”

Tests leave nothing to chance
The adoption of Beijer Electronics as one of very few PC suppliers to MAN Diesel & Turbo has been a lengthy process. The EPC boxes have been tested, methodically and very thoroughly, over a long period.

Niels Torres Engel and Thomas Lehnemann, who are responsible for research and reliability, leave nothing to chance. For their rigorous testing, they have a small ‘torture chamber’ at their disposal in the company’s Research and Development division. “Among the formal requirements, the products have to be type-approved by the leading maritime classification associations,” says Niels Torres Engel, explaining that, after the preliminary screening, the different computers are installed in test beds to confirm their compatibility, performance and quality.

Ready for a harsh environment
In the engine room of a ship, it can get really hot. That is why checks are made to ensure that the computers will still work in 70-degree Celsius temperatures. The EPC boxes from Beijer Electronics met this challenge – as well as the vibration and humidity tests. “By ‘stressing’ the products, we pick up any faults that might not show up at first.” Thomas Lehnemann stresses the importance of ensuring that manufacturers do not make any sudden design modifications. Even minor changes to components can affect the programs running in the computer. “We perform constant spot-checks to ensure that the equipment supplied is up to the mark, and we are in constant contact with our partners.”

Responsive collaboration
The partnership with Beijer Electronics is described as personal, relaxed and good. As Kennet Palm says, if communication with the suppliers isn’t working, it doesn’t matter how good the products are:
“We feel that our wishes are listened to and we get all the help we need” and Niels Torres Engel readily agrees. He freely admits that MAN Diesel & Turbo could be described as a ‘difficult’ customer:
“Although we’re not buying vast quantities of industrial computers, we are extremely fussy about the quality of what we get. Not just that the collaboration works well; it also saves time because all EPC boxes are supplied pre-configured.”

Customised solution
The computers supplied are ready to use right out of the box. The operating system and the relevant drivers and programs are already installed by Beijer Electronics before delivery.

This close dialogue has brought improvements in the onboard systems, which also increases safety. If a control computer should fail – against all the odds – the crew on board can re-install the operating system and programs. This backup copy used to be held on a CD, but unfortunately the mechanisms in the CD drives could not always cope with the vibration they were exposed to. The EPC boxes introduced the idea of restoring from a USB stick, a much more robust solution.
“It is a pleasure to work with suppliers who suggest ideas that provide value and inspiration,” they conclude

The technology in brief
The Beijer Electronics EPC box is a robust, maintenance-free and well-protected industrial computer for tough environments. In purely technical terms, it is built around Intel processors with Windows XP Embedded. Fanless processors keep the temperature down and reduce wear. The industrial computer is IP20-rated according to DIN EN 60529. Plenty of connections make for great flexibility. Parallel and serial ports are standard, along with USB 2.0 sockets and 100 Mbps Ethernet. MAN Diesel & Turbo has chosen flash disk for data storage. The alternative is a traditional vibration-tolerant hard disk. Beijer Electronics’ EPC series is certified by the ABS (American Bureau of Shipping), Bureau Veritas, DNV, Germanischer Lloyd, Lloyd’s Register and the Russian Maritime Register of Shipping.

A mechanical giant
All development, both electronic and mechanical, of MAN Diesel & Turbo’s two-stroke engines is carried out in Denmark. Although some special parts are still made in Denmark, the engines are now built under license in countries like Korea and China by partner companies such as Hyundai Heavy Industries – physically close to the shipbuilding yards that buy the engines.

The electronic control systems manage enormous forces. The engines may output up to 115,000 horsepower and weigh up to 2,000 tons. The cylinders, between six and fourteen in number, have a stroke length of almost five meters. A mechanical efficiency of over 50 percent – the best cars achieve 25 percent – makes for high energy efficiency.

It is no accident that MAN Diesel & Turbo uses industrial computers from Beijer Electronics as human machine interface (HMI) for the company’s giant B&W engines. The choice was based on a very thorough evaluation and negotiation process, in which suppliers from all over the world were compared against each other. On board ships, reliability is absolutely crucial, so all components in the redundant control system have to be of the highest quality.