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Methodology for assessing chemical contamination in aquatic ecosystems of natural areas

It has been used to analyse waters in 21 Important Bird and Biodiversity Areas (IBA) in Spain, in the frame of the LIBERA Project. The methodology enables the detection of 59 different types of contaminants and will allow to assess the potential impact of this threat on the fauna in the aquatic ecosystems.

Among the different natural areas, watercourses near to agricultural habitats, coastal aquatic habitats and water masses in riparian forests are the most affected environments by chemical pollution, being a key factor the proximity to urban centres. In the picture, a scientist is collecting samples in this project. Credits: EFE/Javier Cebollada

Some of the most serious, damaging and worrying pollution problems are imperceptible to the senses and this would explain why we spent too long without paying attention to their causes and consequences. It is the case of chemical contamination, caused by the introduction of potentially toxic substances into the environment.

This contamination is associated with human activities, and it is one of the most harmful for different reasons: it usually involves a wide range of chemical substances with a high toxic potential and persistence, it is not restricted to a geographical area and it is virtually invisible. Its health effects are manifested silently, without drawing attention. This contamination often becomes chronic and affects the population, jeopardizing the survival of many species.

Chemical pollution and its effects are of particular concern when they reach aquatic ecosystems, as they lead to habitat degradation and biodiversity loss in many fragile places. Even the theoretically most pristine natural spaces, such as the Important Bird and Biodiversity Areas (IBA), are not free from this environmental problem.

Important Bird and Biodiversity Areas (IBA) are places of high ecological value and importance for the conservation of biodiversity, especially for bird populations. These locations were identified by BirdLife International based on scientific criteria.

Tracking pollution in biodiversity hotspots

The assessment of pollution in biodiversity hotspots such as the IBA is not usually included within the framework of environmental monitoring programs due to its difficulty, since it requires an intense sampling effort, logistics and coordination, from the sampling in the field to the analysis in the laboratory. These samples also require the use of multi-residue analysis methods, capable of simultaneously detect various types of contaminants whose concentrations are theoretically expected to be low.

To address the problems of chemical pollution that can be generated in natural areas of high ecological value, a scientific team led by the researcher Sílvia Lacorte from the Instituto de Diagnóstico Ambiental y Estudios del Agua (Institute for Environmental Assessment and Water Research, IDAEA – CSIC), the Spanish Society of Ornithology SEO/BirdLife and the Hunting Resources Research Institute (IREC – CSIC, UCLM, JCCM), has developed a methodological procedure to determine simultaneously a large number of organic micropollutants from different chemical families. The method has been applied to analyse water samples collected in 21 IBA in Spain.

83% of the chemical substances analysed have been detected in the samples of these natural areas

The results of this methodology show how often is detected each pollutant in the analysed samples (left) and the number and type of chemical substances detected in different habitats of the IBA, as well as the concentration (ng/L) (right).

The analytical part of the methodological procedure is based on the use of liquid chromatography techniques coupled to tandem mass spectrometry (LC-MS/MS). Using this technique, the scientists have analysed simultaneously 21 drugs, 17 plant protection products, 3 organophosphate esters, 17 perfluorinated compounds and benzophenone.

As the results show, 83% of the chemical substances analysed (from a total of 59) have been detected, which demonstrates that even natural areas of high ecological value suffer the impact of chemical contamination.

Caffeine, drugs such as ibuprofen or paracetamol, and organophosphate esters are the most ubiquitous

Among the micropollutants studied, caffeine, drugs such as ibuprofen or paracetamol, and organophosphate esters are the most ubiquitous. Caffeine, which was detected in 79% of the samples, is an indicator of human intrusion into natural spaces.

Presence of drugs in 98% of the samples

The presence of drugs in the water of the IBAs, detected in 98% of the samples, is especially worrying from an ecological perspective because these chemical compounds are bioactive, therefore they can interfere with gene regulation and expression of organisms. They can also affect the development of vertebrates, as well as their immune, neuroendocrine and cardiovascular systems.

According to the European Medicines Agency (EMA), when drug concentration in water overcomes the limit of 10 ng/L it is necessary to carry out an ecotoxicological risk assessment. Unfortunately, 12% of the samples analysed in this study exceed this limit.

Among the different natural areas, watercourses near to agricultural habitats, coastal aquatic habitats and water masses in riparian forests are the most affected environments by chemical pollution, being a key factor the proximity to urban centres.

On the other hand, organophosphorus esters have been detected in 76% of the samples. These chemical compounds are used as a flame retardants and additives in plastics, paints and other furniture materials and electronic components.

Other chemical pollutants, such as phytosanitary products (associated with agricultural activities), perfluorinated compounds (a component of goretex, teflon, or fire-fighting foams and used in the agrochemical industry) and benzophenone (used in cosmetics and in the plastic industry) were detected in 60, 29 and 17% of the analysed samples, respectively.

This methodological procedure applied as a proof of concept has been developed and implemented within the framework of the LIBERA Project, promoted by SEO/BirdLife in alliance with Ecoembes.

The results highlight the need to allocate more research and management efforts to assess chemical pollution, the invisible "garbage", even in natural spaces of Spain that, in theory, are considered free of anthropic pressure. This could be assessed through the identification of contaminating sources and substances, as well as the evaluation of their impact on fauna.

Reference article

Dulsat-Masvidal, M., Ciudad, C., Infante, O., Mateo, R. Lacorte S. 2022. Pilot monitoring scheme of water pollutants in Important Bird and Biodiversity Areas. Ecotoxicology and Environmental Safety 237, 113562.


Jaime Rodríguez Estival / IREC-CSIC
Alicia Arroyo / IDAEA-CSIC Comunicación
Olimpia García / SEO/BirdLife