( cest2017_00783) Use of passive sampling devices for monitoring emerging contaminant metaldehyde

摘要

Metaldehyde is the active ingredient in 80% of slug pelletsused globally. Metaldehyde is not phytotoxic and is usedby arable farmers to protect crops such as cereals, oilseedrape, and potatoes and has been identified as an emergingcontaminant by NORMAN. High mobility and extensiveuse allow metaldehyde to enter surface waters where it hasbeen detected above the EU Drinking Water Directivelimit of 0.1 μg/L. Water quality monitoring programs relyon the collection of infrequent (2-4 weeks) high volumespot/grab water sampling. This is expensive and timeconsumingand can miss sporadic inputs having seriousimplications for water quality management. We havedeveloped a new variant of the Chemcatcher~R (an easy touse, low-cost passive sampling device) for a suite of polarpesticides including metaldehyde which utilises ahydrophilic/lipophilic balance sorbent (Horizon AtlanticHLB-L) as the receiving disk. Initial trials for themetaldehyde Chemcatcher~R were undertaken at threecatchment sites along the river Thames, where previousspot sample data shows drastic fluctuations in metaldehydeconcentrations over time. Spot sample concentrations weremeasured at concentrations of 71- 309 ngL-1 during thetwo week deployment interval, with the Chemcatcher~Rdemonstrating a TWA concentration 159 ng L-1 (with goodagreement to the mean concentration of spot samples). Itwas therefore determined that the MetaldehydeChemcatcher~R can provide accurate reporting and act as asupplement for metaldehyde monitoring programmes.