Temporal and spatial patterns of metaldehyde in semi-agricultural catchments in Essex, UK: The influence of application regimes and hydrological conditions.
Abstract
Metaldehyde, a widely used molluscicide, is one of the most commonly detected pesticides in aquatic environments in the UK. The following study is the first analysis of long-term metaldehyde concentration data, where pesticide concentrations and fluxes in stream water over a ten-year period (2008-2018) were investigated at a catchment scale, and the impact of hydrological conditions and application regime on metaldehyde levels assessed.
Patterns of seasonal and annual presence of metaldehyde were assessed in two areas in Essex, southeast England, with contrasting catchment-based approaches to management of water quality: the Ardleigh catchment, where farmers are incentivised to use slug control methods as an alternative to metaldehyde since 2015; and the River Colne catchment with on-going seasonal applications of metaldehyde. Metaldehyde concentration peaks displayed a seasonal pattern, mainly occurring during the application season between September and December, and were associated with a hydrological regime of high intensity (stream flow up to 18 m3 s-1, daily rainfall >10mm). Metaldehyde concentrations during time periods when the molluscicide is not applied to agricultural land and when applied to spring and summer crops were considerably lower (0.01-0.03 µg L-1). Peaks in metaldehyde concentration typically did not exceed 0.5 µg L-1.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH056.0024B
- Keywords:
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- 1804 Catchment;
- HYDROLOGY;
- 1806 Chemistry of fresh water;
- HYDROLOGY;
- 1848 Monitoring networks;
- HYDROLOGY;
- 1879 Watershed;
- HYDROLOGY