Impact of Sediment-Spiked Fludioxonil On Benthic Macroinvertebrates And Zooplankton From The Yangtze River Delta, China

Abstract

In China, the fungicide fludioxonil, that accumulates and persists in sediments, has a widespread agricultural use to control various fungal diseases. Its residues may cause toxic effects to benthic and pelagic aquatic fauna, thereby impacting ecosystem service functions of aquatic ecosystems.To assess the environmental risks of fludioxonil, sediment-spiked single-species toxicity tests with benthic macroinvertebrates as well as a sediment-spiked indoor freshwater microcosm experiment were performed. The microcosm test systems were populated with benthic invertebrates also used in the single-species tests. In all experiments artificial sediment was used. The single-species tests were conducted with 8 benthic macroinvertebrates covering different taxonomic groups typical for the Yangtze River Delta, China. The 28d-EC10 values thus obtained were used to construct species sensitivity distributions (SSDs) and the hazardous concentration to 5% of the species tested (HC5) was used to derive a provisional long-term Tier-2 regulatory acceptable concentration (RAC) for benthic invertebrates by applying an assessment factor of 3.The microcosm experiment was conducted to study treatment-related responses of benthic macroinvertebrates and pelagic zooplankton. The lowest No Observed Effect Concentrations (NOECs) of benthic invertebrate and of pelagic zooplankton populations were used to derive provisional long-term Tier-3 RACs for, respectively, benthic and pelagic invertebrates by applying an assessment factor of 2. The RACs thus obtained were compared with Predicted Environmental Concentrations (PECs) of fludioxonil in overlying water and the sediment compartment of edge-of-field ponds after application of this fungicide in rice, grape, wheat, maize and tomato crops. Overall, the risks of long-term exposure of fludioxonil to benthic invertebrates and pelagic zooplankton species in these Chinese edge-of-field ponds appear to be relatively small, but some risks cannot be excluded for ponds adjacent to rice.