Determining the concentration of POPs (Persistent Organic Pollutants) such as total dichlorodiphenyltrichloroethane (DDTtot) and polychlorinated biphenyls (PCBs) in the zooplankton is essential for evaluating the level of toxicity in the environment and the risk to ecosystem health. The extent to which POPs persist in the environment and affect human health depends on accumulation in the different components of the zooplankton community such as particle feeders and/or predators and their subsequent consumption by fish, which varies seasonally. We analyzed ten-years (2011-2020) of seasonal data on POPs in the crustacean zooplankton community of Lake Maggiore (Italy). The concentration of total DDTs, as sum of all congeners ranged between 23.5 and 156.9 ng/g dry weight, while sumPCB14 ranged from 24.4 and 133.6 ng/g dry weight. We traced particle feeders' vs predatory taxa within the zooplankton community using carbon and nitrogen stable isotopic values. POPs concentration was significantly related to the nitrogen isotopic values. The zooplankton biomass increase in Spring was important, both through this being a period of increased metabolism and activity of planktivorous fish and also as it was the period when the zooplankton repository of POPs was at a maximum. DDTtot stocked in zooplankton ≥450 μm was up to 275 ng/m2, while sumPCB14 was 285 ng/m2 in 2013. A decrease of DDTtot stocked in the zooplankton repository characterized the last five years examined, when mean annual values (14.8-56.9 ng/m2) were less than half those of the previous period (50.7-128.6 ng/m2).
Keywords: DDT; Freshwater zooplankton; Lake Maggiore; PCB; Persistent Organic Pollutants; Stable Isotope Analysis.
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