title: Evaluation of spot and passive sampling for monitoring, flux estimation and risk assessment of pesticides within the constraints of a typical regulatory monitoring scheme.
abstract: In many agricultural catchments of Europe and North America, pesticides occur at generally low concentrations with significant temporal variation. This poses several challenges for both monitoring and understanding ecological risks/impacts of these chemicals. This study aimed to compare the performance of passive and spot sampling strategies given the constraints of typical regulatory monitoring. Nine pesticides were investigated in a river currently undergoing regulatory monitoring (River Ugie, Scotland). Within this regulatory framework, spot and passive sampling were undertaken to understand spatiotemporal occurrence, mass loads and ecological risks. All the target pesticides were detected in water by both sampling strategies. Chlorotoluron was observed to be the dominant pesticide by both spot (maximum: 111.8ng/l, mean: 9.35ng/l) and passive sampling (maximum: 39.24ng/l, mean: 4.76ng/l). The annual pesticide loads were estimated to be 2735g and 1837g based on the spot and passive sampling data, respectively. The spatiotemporal trend suggested that agricultural activities were the primary source of the compounds with variability in loads explained in large by timing of pesticide applications and rainfall. The risk assessment showed chlorotoluron and chlorpyrifos posed the highest ecological risks with 23% of the chlorotoluron spot samples and 36% of the chlorpyrifos passive samples resulting in a Risk Quotient greater than 0.1. This suggests that mitigation measures might need to be taken to reduce the input of pesticides into the river. The overall comparison of the two sampling strategies supported the hypothesis that passive sampling tends to integrate the contaminants over a period of exposure and allows quantification of contamination at low concentration. The results suggested that within a regulatory monitoring context passive sampling was more suitable for flux estimation and risk assessment of trace contaminants which cannot be diagnosed by spot sampling and for determining if long-term average concentrations comply with specified standards.
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK. Electronic address: zulin.zhang@hutton.ac.uk.
authors.forename: Zulin
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
authors.forename: Mads
authors.initials: M
authors.lastname: Troldborg
authors.affiliation: The Robert Gordon University, Riverside East, Garthdee, Aberdeen AB10 7JG, UK.
authors.forename: Kyari
authors.initials: K
authors.lastname: Yates
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Osprey
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
authors.forename: Christine
authors.initials: C
authors.lastname: Kerr
authors.affiliation: University of Aberdeen, St Machar Drive, Aberdeen AB24 3UU, UK.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Hallett
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
authors.forename: Nikki
authors.initials: N
authors.lastname: Baggaley
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
authors.forename: Stewart M
authors.initials: SM
authors.lastname: Rhind
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
authors.forename: Julian J C
authors.initials: JJC
authors.lastname: Dawson
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
authors.forename: Rupert L
authors.initials: RL
authors.lastname: Hough
mesh_terms: D004784:Environmental Monitoring / Q000331:legislation & jurisprudence / Q000379:methods*; D058735:Environmental Policy / Q000331:legislation & jurisprudence; D005062:European Union; D033161:Government Regulation; D010575:Pesticides / Q000032:analysis*; D018570:Risk Assessment; D045483:Rivers / Q000737:chemistry*; D012606:Scotland; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Fluxes; Monitoring; Passive sampling; Pesticides; Risk assessment; Water