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Evaluation of spot and passive sampling for monitoring, flux estimation and risk assessment of pesticides within the constraints of a typical regulatory monitoring scheme.

Zhang, Zulin; Troldborg, Mads; Yates, Kyari; Osprey, Mark; Kerr, Christine; Hallett, Paul D.; Baggaley, Nikki; Rhind, Stewart M.; Dawson, Julian J.C.; Hough, Rupert L.


Zulin Zhang

Mads Troldborg

Mark Osprey

Christine Kerr

Paul D. Hallett

Nikki Baggaley

Stewart M. Rhind

Julian J.C. Dawson

Rupert L. Hough


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: 111.8 ng/l, mean: 9.35 ng/l) and passive sampling (maximum: 39.24 ng/l, mean: 4.76 ng/l). The annual pesticide loads were estimated to be 2735 g and 1837 g 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.


ZHANG, Z., TROLDBORG, M., YATES, K., OSPREY, M., KERR, C., HALLETT, P.D., BAGGALEY, H., RHIND, S.M., DAWSON, J.J.C. and HOUGH, R.L. 2016. Evaluation of spot and passive sampling for monitoring, flux estimation and risk assessment of pesticides within the constraints of a typical regulatory monitoring scheme. Science of the total environment [online], 569-570, pages 1369-1379. Available from:

Journal Article Type Article
Acceptance Date Jun 17, 2016
Online Publication Date Jul 15, 2016
Publication Date Nov 1, 2016
Deposit Date Aug 22, 2016
Publicly Available Date Jul 16, 2017
Journal Science of the total environment
Print ISSN 0048-9697
Electronic ISSN 1879-1026
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 569-570
Pages 1369-1379
Keywords Pesticides; Passive sampling; Monitoring; Fluxes; Risk assessment; Water
Public URL


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