Details of Award
NERC Reference : NE/L009145/1
Development of a passive sampler for monitoring sources and fluxes of metaldehyde in natural waters and response to stochastic storm events
Training Grant Award
- Lead Supervisor:
- Professor G Fones, University of Portsmouth, Sch of Earth & Environmental Sciences
- Grant held at:
- University of Portsmouth, Sch of Earth & Environmental Sciences
- Science Area:
- Freshwater
- Marine
- Terrestrial
- Overall Classification:
- Freshwater
- ENRIs:
- Environmental Risks and Hazards
- Natural Resource Management
- Pollution and Waste
- Science Topics:
- None
- Abstract:
- Metaldehyde is the active ingredient in 80 % of slug pellets. Farmers and agriculturalists apply between 6,000-10,000 t of metaldehyde as slug pellets to land every year to protect crops. Most lowland rivers contain significant quantities (0.2-2 ug/L) of metaldehyde, with peak concentrations reaching over 4 ug/L in several water catchments (data from Water UK, September 2011 onwards). Some of these concentrations put the UK at risk of breaching regulatory limits (0.1 ug/L) of the Water Framework Directive (WFD) and the Drinking Water Directive (98/83/EC) (DWD). Data from spot sample monitoring shows a clear relationship between periods of agricultural application of pellets (autumn) and peak concentrations in river water (autumn through to winter). Metaldehyde enters the aquatic environment as run-off following periods of rainfall and concentrations can vary due to stochastic storm events. Riverine contamination is considered to relate primarily to agricultural use of the product. It is likely that metaldehyde is reaching rivers and groundwater via a combination of pathways (a) point sources such as spills during filling the spreader, or when moving bags or sacks of pellets (b) misdirected spreading across field margins, ditches and water courses (c) diffuse leaching via land drains, and land run-off, when pellets are spread onto saturated ground or when rain is imminent, and where poor soil management causes enhanced run-off. Currently environment agencies in UK are tasked with monitoring a range of organic priority substances, including metaldehyde, in rivers as part of the EU's WFD. The conventional method of sampling using spot/bottle water samples has the potential to miss fluctuations in concentration. This is a serious limitation in field investigations when trying to predict relationships between biological effects and pesticide exposure. This problem is increased during storm events, particularly when monitoring sites in a catchment separated by large distances. Some of the difficulties in measuring accurate concentrations of pesticides can be overcome by the use of passive samplers. Over the past 20 years, several designs of passive samplers have been developed to monitor a range of pollutant types (non-polar and polar organics, organo-metals and metals) present in the aquatic environment. They consist of a receiving phase with a high affinity for the pollutant of interest, which is then exposed to the aquatic medium for a defined period of time. Depending on the sampler design and time of deployment in the field, the mass of a pollutant accumulated by a device can reflect either the equilibrium concentration or the time-weighted average (TWA) concentration of the pollutant in the water column. These samplers can be used to accumulate contaminants over extended deployment periods (days to months). This means that large volumes of water can be cleared by the devices and, hence, the samplers effectively pre-concentrate pollutants, lowering the effective level of detection of environmental chemicals. This project aims to further develop the UoP's Chemcatcher passive sampler and assess other designs of samplers to produce a robust and reliable device suitable for monitoring metaldehyde in river basins (including extraction points) and investigate the compound's fate when entering into estuaries. The samplers will be of value to a number of end-uses such as water companies, regulators and consultancies. The new device will be tested in the laboratory and validated during field trials involving the South-West Water (CASE) and project partners, Natural Resources Wales (NRW) and the Centre for Ecology & Hydrology (CEH). Passive samplers will be deployed at a number of pre-determined sites to help answer the important questions such as sources of metaldehyde, exposure time in the water (mass loadings) and what impact storms and heavy rainfall have on the concentration metaldehyde exceeding WFD and DWD regulatory values.
- NERC Reference:
- NE/L009145/1
- Grant Stage:
- Completed
- Scheme:
- DTG - directed
- Grant Status:
- Closed
- Programme:
- Industrial CASE
This training grant award has a total value of £83,515
FDAB - Financial Details (Award breakdown by headings)
| Total - Fees | Total - Student Stipend | Total - RTSG |
|---|---|---|
| £16,226 | £56,292 | £11,000 |
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