Person: Weisner, Oliver
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1992
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Umwelttoxikologe
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Weisner
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Oliver
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Veröffentlichung Width of vegetated buffer strips to protect aquatic life from pesticide effects(2023) Liebmann, Liana; Vormeier, Philipp; Liess, Matthias; Weisner, OliverVegetated buffer strips (VBS) are an effective measure to retain pesticide inputs during rain events. Numerous studies have examined the retention effects of VBS onpesticides. However, no study has addressed on a large scale with event-related peak concentrations how wide the VBS should be to avoid ecological impacts onaquatic life. Here, we investigated for 115 lowland stream sections in Germany the relevance of environmental and physico-chemical parameters to determine the in-stream pesticide concentration and their ecological risks. Based on peak concentrations related to rain events with precipitation amount resulting in VBS relevantsurface runoff for 30 of the 115 investigated stream sections (25 to 70 mm/d), we demonstrated that the average width of VBS was the main parameter (R2 = 0.38)reducing the pesticide input ratio, indicating a relevant proportion of surface runoff contributing to the total in-stream pesticide concentrations. Additionally, dryditches within agricultural fields increased pesticide input (R2 = 0.31). Generally, substances classified as slightly mobile were better retained by VBS than mobilesubstances. Other factors including slope, land use and vegetation cover of VBS had only a minor influence. We assessed the ecological risk of in-stream pesticideconcentrations by quantifying exceedances of regulatory- (RAC) and field-validated acceptable concentrations (ACfield). We then translated this ecological risk intoprotective VBS width by calculating the quotient of in-stream concentration and threshold (RQ). We estimate that a VBS width of 18 m is sufficient to meet theRQACfield protection goal for 95% of streams. The presence of dry ditches increased the protective VBS width to 32 m. In current agricultural practice, however, 26%of the water stretches investigated do not comply with the prescribed 5 m VBS. An extension of the VBS area to 18 m would demand 3.8% of agricultural land withinthe catchments. A 50% reduction in pesticide use, as required by the European green deal, would still result in 39% (RAC) and 68% (ACfield) of event-related samplesbeing exceeded. Consequently, we see the extension of the VBS width as the most efficient mearsure to sustainably reduce pesticide concentrations in small streams. © 2023 ElsevierVeröffentlichung Three reasons why the Water Framework Directive (WFD) fails to identify pesticide risks(2021) Arle, Jens; Liebmann, Liana; Weisner, OliverThe Water Framework Directive (WFD) demands that good status is to be achieved for all European water bodies. While governmental monitoring under the WFD mostly concludes a good status with regard to pesticide pollution, numerous scientific studies have demonstrated widespread negative ecological impacts of pesticide exposure in surface waters. To identify reasons for this discrepancy, we analysed pesticide concentrations measured in a monitoring campaign of 91 agricultural streams in 2018 and 2019 using methodologies that exceed the requirements of the WFD. This included a sampling strategy that takes into account the periodic occurrence of pesticides and a different analyte spectrum designed to reflect current pesticide use. We found that regulatory acceptable concentrations (RACs) were exceeded for 39 different pesticides at 81% of monitoring sites. In comparison, WFD-compliant monitoring of the same sites would have detected only eleven pesticides as exceeding the WFD-based environmental quality standards (EQS) at 35% of monitoring sites. We suggest three reasons for this underestimation of pesticide risk under the WFD-compliant monitoring: (1) The sampling approach - the timing and site selection are unable to adequately capture the periodic occurrence of pesticides and investigate surface waters particularly susceptible to pesticide risks; (2) the measuring method - a too narrow analyte spectrum (6% of pesticides currently approved in Germany) and insufficient analytical capacities result in risk drivers being overlooked; (3) the assessment method for measured concentrations - the protectivity and availability of regulatory thresholds are not sufficient to ensure a good ecological status. We therefore propose practical and legal refinements to improve the WFD's monitoring and assessment strategy in order to gain a more realistic picture of pesticide surface water pollution. This will enable more rapid identification of risk drivers and suitable risk management measures to ultimately improve the status of European surface waters. © 2021 Elsevier Ltd.