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Organisationseinheit der BAM
Rainfall-triggered runoff is a major driver of pesticide input in streams. Only few studies have examined the suitability of passive sampling to quantify such episodic exposures. In this study, we used Empore-TM styrene-divinylbenzene reverse phase sulfonated disks (SDB disks) and event-driven water samples (EDS) to assess exposure to 15 fungicides and 4 insecticides in 17 streams in a German vineyard area during 4 rainfall events. We also conducted a microcosm experiment to determine the SDB-disk sampling rates and provide a free-software solution to derive sampling rates under time-variable exposure. Sampling rates ranged from 0.26 to 0.77 L d-1 and time-weighted average (TWA) concentrations from 0.05 to 2.11 µg/L. The 2 sampling systems were in good agreement and EDS exceeded TWA concentrations on average by a factor of 3. Our study demonstrates that passive sampling is suitable to quantify episodic exposures from polar organic pesticides.
Background and aims
Olive mill wastewater (OMW) generated in Mediterranean countries is partly disposed of on soil. Its underlying fate mechanisms and influences on plant growth are still largely unknown. Our goal was to understand OMW organic matter (OMW-OM) degradation in soil and its phytotoxic effects. We hypothesized that OMW phytotoxicity decreased with degradation of its phenolic components.
Methods
In a 60 day incubation study, we monitored soil respiration, extractable total phenolic content (TPC) and carbon isotope ratio (δ13C) of OMW treated Israeli soil. The soil was extracted using accelerated solvent extraction (ASE) and its extracts were exemplarily analyzed for four phenolic substances by LC/MS. Phytotoxicity of soil and soil extracts were tested using a Lepidium sativum seed germination bioassay.
Results
Soil respiration was 2.5 times higher for OMW treated soil with two respiration maxima and indicated a degradation of up to 27 % of the added OMW-OM. Four phases of OMW-OM degradation were identified: (i) degradation of easily degradable OMW-OM and transformation of phenolic compounds, (ii) intermediate suppression of phytotoxicity, (iii) degradation of phytotoxic phenolic compounds and (iv) significant physical immobilization of phytotoxic compounds.
Conclusion
Environmental conditions during and after OMW disposal on soil ought to favor fast degradation of OMW-OM, minimizing their physical immobilization and phytotoxic effects.