The Chemistry Laboratory of the Institut de Ciències del Mar (ICM-CSIC) offers a Nutrient Analysis Service to institutions and companies, where they analyse the main nutrients in water. Specifically, they measure the concentration of inorganic nutrients (nitrate, nitrite, ammonium, phosphate, and silicate), total nitrogen and phosphorus, and total and dissolved organic carbon.

These nutrients are essential for the microorganisms that form the base of aquatic food webs, such as microalgae and phytoplankton, which in turn serve as food for fish and crustaceans. They are also indicators of water quality and ecosystem balance. / istock

These nutrients are essential for the microorganisms that form the base of aquatic food webs, such as microalgae and phytoplankton, which in turn serve as food for fish and crustaceans. These chemical compounds are also indicators of water quality and ecosystem balance.

"Photosynthetic organisms incorporate carbon, generate oxygen and glucose, and thus life begins," explains Elisa Berdalet, Institut de Ciències del Mar (ICM-CSIC) y researcher and director of the Nutrient Service. "Phytoplankton needs nitrogen, phosphorus, and silicate, especially in the case of diatoms, small algae with a silica cell wall." In turn, microalgae contribute to the production of organic forms of carbon, nitrogen, and phosphorus, which will be consumed by other organisms. Therefore, the concentration of all these elements is an indicator of biogeochemical and microbial processes in water.

"In the open sea, nutrients are supplied by the upwelling of deep waters to the surface and by rivers and runoff waters near the coast. The chemical composition also provides information about the components of water masses and the dynamics of marine circulation, the land-sea interaction at the coast, as well as the inputs of human origin (fertilizers) and natural origin (through erosion) to coastal waters via rivers," points out Elisa Berdalet, who also leads the Plankton Ecology and Ocean Health research group.

The laboratory is highly specialized in the analysis of seawater, which is much more complex than the analysis of freshwater samples

Specialized in Seawater

The laboratory is highly specialized in the analysis of seawater, which is much more complex than the analysis of freshwater samples. "Seawater has a very low concentration of analytes, thousands of times lower than the usual concentrations in freshwater, which requires therefore highly sensitive analysis instruments and protocols," explains Maravillas Abad, the technical manager of the ICM-CSIC Nutrient Service. Additionally, she adds, "the samples have a high salt content, requiring a rigorous protocol to prevent the salts from damaging the equipment circuits."

Although most of the samples they receive are from the Mediterranean coast, they also analyse samples from all over the world. "On one occasion, a French university commissioned us to analyse hundreds of samples from the Rhône tributaries, which we had to do in the summer and in record time," adds Abad.

The laboratory provides services to public institutions, research centres and universities, water agencies and authorities, ports, and also to companies, especially environmental companies, and fish farms, which are subject to European regulations on maximum nitrate and phosphate levels in water. In the case of desalination plants, the researchers explain, "desalinated water cannot contain organic carbon; the sensitivity level of the analyses we perform contributed to the commissioning of the desalination plant in El Prat, in Barcelona."

Nutrient Analysis Service Team. From left to right, Maravillas Abad, Technical Manager; Elisa Berdalet, Service Director; and Núria González.

Most of their projects are for environmental impact reports, such as those conducted before and after the commissioning of offshore oil fields, aquaculture facilities, desalination plants, and wastewater treatment plants. They also monitor human-origin pollution on the coast. However, they typically conduct the analyses without knowing their purpose, "blindly," to maintain maximum objectivity in the testing.

Many samples are from research campaigns, which, as Mara Abad points out, "arrive frozen from very different places: pristine areas, tropical oceans, nutrient-poor Mediterranean oceanic waters, the Atlantic, the Dead Sea, or Antarctica." Although ideally, the samples should be analysed ‘fresh’, "freezing is the only way to keep them intact until they reach the laboratory, even if it means some alterations to the sample.

In 2023, they participated in a campaign in which 14 laboratories from around the world, equipped with their instruments, simultaneously collected and analyzed ocean samples with the aim of comparing analysis protocols

There are other factors that can influence and alter analysis results. In the case of carbon, ambient air CO2 can be absorbed by the sample if it remains exposed for too long before analysis. To prevent this, at the ICM laboratory, samples are introduced one by one into the analysis equipment. 

Searching for an international standard

The laboratory is working to obtain ISO accreditation and is also collaborating to establish an international standard protocol with other European laboratories. In 2023, they embarked on an ocean campaign coordinated by the Australian national research agency (CSIRO), involving 14 laboratories from around the world, each one on board with its instruments. Over several days, they collected samples from different points in the ocean and analysed them fresh, simultaneously and immediately on board. This way, they identified sources of variability in analysis protocols.

 The aim was to share methodologies and ensure that analyses are conducted using the same methodology. "It is important to have an international standard," says Elisa Berdalet, "to ensure that results of international research are comparable. And this is achieved through practice and sharing practices," something especially important in international studies on climate and ocean protection. Next September, she announces, "we will meet again in a workshop in France, to share the data from that campaign and see if it is possible to improve the protocol.”

Contact:

Nutrient Analysis Service
Tel  932309500 (ext. 445582)
http://anqui.icm.csic.es/en