Item

Abstract

Lentic small water bodies (LSWB) are widespread globally. They fulfill a variety of ecohydrological tasks and are of central importance for biodiversity in rural areas. Due to their size and location, they interact with their environment in complex ways not found in other types of water bodies. Plant protection products (PPP) and their transformation products (TP) pose a particular risk to them. However, the database of their contamination is low and inhomogeneous and transport pathways have not been sufficiently investigated so far. This study focuses on two LSWB in northern Germany that were monitored for their PSM/TP contamination and hydrological connectivity in a high-resolution measurement campaign from 10/1/20 to 10/31/21. Surface runoff, lateral flow, groundwater, drainage water, and surface water of the LSWB were analyzed for 26 PPP/TP. Based on recorded hydrological data and tracer experiments, water balances were established. Results show multiple findings of up to eight PPP/TP in all samples. In addition, several input and output pathways as well as different temporal dynamics of the various PPP/TP concentrations were identified. A pronounced interaction between the LSWB and the shallow groundwater enabling a PPP/TP exchange was observed. LSWB and shallow groundwater showed a constant and high load of the non-applied TP metazachlor-ESA. Metazachlor-ESA was measured with the highest concentrations of up to 11.66 µg L^-1 in the shallow groundwater and loads of up to 3.12 g in a single inflow per month. For one of the LSWB, a drainage system was a major input pathway for PPP/TP.