A study by the Cavanilles Institute of Biodiversity and Evolutionary Biology (ICBiBE), which belongs to the scientific-academic area of the University of Valencia Science Park (PCUV), and the Department of Analytical Chemistry of the Universitat de València shows that artificial wetlands significantly mitigate the presence in water of pollutants, mainly agricultural but also urban and industrial. The research, carried out between 2020 and 2025, concludes that Tancat de la Pipa and l'Illa, in the Albufera Natural Park, reduced the concentration of pesticides and heavy metals/metalloids analyzed in the outlet water by between 50% and 100%, with concentration reductions between 15% and 50%.
The work has analysed samples of water entering, entering and leaving directly or indirectly into the lake of Albufera, the Tancat de la Pipa and the Tancat de l'Illa, as well as samples of sediment, macrophytes and herbivorous bird excrement. The results show that artificial wetlands reduced the concentration in outflow water by 57-100% for fungicides, 67-86% for herbicides and 67-100% for insecticides. In addition, total disposal efficiencies were 15%, 25% and 50% respectively. On the other hand, for metals, the concentration of 50% of elements was lower in wetland outlet waters, with seasonal variations.
The work has also studied the state of waters following the DANA of October 2024, which caused "significantly higher concentrations of certain pesticides (namely carbendazim, metalaxyl, piperonyl butoxide, diuron, diazinon and chlorpyrifos)", but which were reduced in the outlet water by the action of these wetlands.
"The high number of pollutants still detected, including several banned pesticides, together with mercury concentrations, highlight the continuing pressure on the natural park and the important role that built wetlands play.", Nuria Carabal, ICBiBE researcher
In addition to the configuration of manmade wetlands, the particular physical and chemical properties of these compounds influenced the retention of pesticides, so that the immobile (the less soluble ones, which tend to be deposited) accumulated in the sediment, and the (dissolved in water) were incorporated by vegetation and eventually detected in herbivorous bird droppings.
The environmental risks associated with pesticide concentrations, including proscribed compounds still detected in the waters of the natural park, were significantly reduced at outlets from manmade wetlands, this prevented waters with concentrations that pose a moderate and high risk from ending up in the Albufera of Valencia. For metals, although overall risk levels were low, mercury exceeded the limit values set by European legislation, but its concentration was reduced in effluent waters.
"The results of this study reinforce the value of nature-based solutions to improve water quality and protect biodiversity," said Nuria Carabal, from the research team. "The high number of pollutants still detected, including several banned pesticides, together with mercury concentrations, highlight the continuing pressure on the natural park and the important role that built wetlands play.", concludes the researcher.
Source: UV News