|
(M/FF228) Nutrients and contaminants: AQUATOX scenariostudies on modelecosystems and shallow lakes. Moermond, Caroline1, Knijf, Loek2, Zwolsman, John2, Koelmans, Albert1, 1 2 ABSTRACT- Nutrients and toxicants both influence aquatic ecosystem feedback structures. Also, fate of toxicants is governed by physical, chemical and biological processes. AQUATOX was used to model the distribution of pollutants between (a)biotic compartments in algae versus macrophyte dominated systems. Special attention was paid to the influence of trophic state, length of the foodchain and seasons. Scenario studies were perfomed with PCB153, benzo(a)pyrene and chlorpyrifos for modelecosystems and the algae-dominated lake IJsselmeer and macrophyte-dominated lake Wolderwijd in the Netherlands. The calculated biological maxima were in the same order of magnitude as the measured biological maxima. Calculations with AQUATOX showed that the influence of biological processes on the fate of pollutants depends on the system, the substance and the season. Kinetic processes appear to be very important in pollutant fate modelling. Seasonal changes in the calculated biomass of the various functional groups are reflected in the distribution of the pollutants. The algal biomass shows strong seasonality; AQUATOX calculated that during algal growth a large amount of the pollutants is stored in the algae. The importance of fish and invertebrates in the distribution of pollutants is also subject to seasonal influences. In contrast, the addition of extra nutrients and consequently the higher biomass, does not influence the calculated distribution over the various compartments. Calculations indicate that this may be because of biomass dilution: When the algal biomass increases, the total amount of pollutants in the algae remains the same, so the amount of pollutant in mg/kg algae decreases. Key words: ecotoxicology, modelling, modelecosystems, shallow lakes |
