Pesticides and their transformation products in lentic small water bodies - effect of hydrology, substance properties and field management

• Applicant: Dr. Uta Ulrich
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439285197

Lentic small water bodies (LSWB) fulfil numerous ecohydrolological functions and are of high importance for biodiversity in rural areas. Due to their size/location, they undergo complex interactions with their environments, not found with other water bodies, and are thus at greater risk from pesticides. A sound knowledge of pesticide transport and dynamics in terms of LSWB as well as the governing key variable is essential to preserve their functionality. So far, there is only a basic knowledge about transport of water and few nutrients into LSWB. A high resolution temporal/spatial monitoring is required which considers the annual diverse hydrological conditions besides worst case conditions after application to get insides into the dynamic of pesticides in the water body as well. In this project, the transport, the effect of hydrology, substance properties and field management on transport and dynamic of pesticides in LSWB will be studied in 2 LSWB for 2 years to address the following research questions:1. How does the hydrology vary in LSWB of different of connectivity to shallow groundwater?2. Are pesticides and their transformation products transported via one or several pathways into the LSWB? How do the loads split up on the entry paths?3. Are the PSM / TP's physicochemical properties used to determine both the input pathways and the temporal dynamics and concentration in the LSWB, so that, for example, less sorptive pesticides are introduced into the LSWB via subsurface paths in delayed and subdued pulses (slow flow component)?4. Besides management of the surrounding field, do long-term storages in soil and sediment as well as nearby fields have to be considered as source for the detected pesticide/TP findings?The results provide a sound knowledge about the entry pathways pf pesticides/TP into LSWB and the relevance of key variables. These findings are supplemented by a cause study whether positives were relocated from the surrounding field or other sources. The seasonal dynamic of concentrations allows to identify periods of maximum (multiple-) contamination which is of high importance in terms of ecotoxicological assessment. The sensitivity of the key variables applies also here. Based on the gathered data, effective mitigation strategies can be implemented to redunce pesticide inputs considering the individually relevant entry pathways.

• DFG Programme: Research Grants
• Co-Investigator: Professorin Dr. Nicola Fohrer