Charting water quality improvements and practice reversion with pesticide interventions at catchment scale.

Freshwater quality, and the impacts of farming practice on drinking water supplies, are of concern in many countries and time-limited catchment management interventions are commonly used to improve water quality. However, ending such schemes may result in practice reversion. This study adopts an interdisciplinary approach combining evidence from water quality monitoring data with a behavioural study of farmers to explore changes in land use practice with reference to the pesticide MCPA (2-methyl-4-chlorophenoxyacetic acid) following a catchment-based management scheme delivered in the cross-border Derg catchment in Northern Ireland/Ireland between 2018 and 2021.

Evaluation of Chemcatcher® passive samplers for pesticide monitoring using high-frequency catchment scale data.

Passive samplers (PS) have been proposed as an enhanced water quality monitoring solution in rivers, but their performance against high-frequency data over the longer term has not been widely explored. This study compared the performance of Chemcatcher® passive sampling (PS) devices with high-frequency sampling (HFS: 7-hourly to daily) in two dynamic rivers over 16 months. The evaluation was based on the acid herbicides MCPA (2-methyl-4-chlorophenoxyacetic acid), mecoprop-P, fluroxypyr and triclopyr.

Quantifying MCPA load pathways at catchment scale using high temporal resolution data.

Detection of the agricultural acid herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid) in drinking water source catchments is of growing concern, with economic and environmental implications for water utilities and wider ecosystem services. MCPA is poorly adsorbed to soil and highly mobile in water, but hydrological pathway processes are relatively unknown at the catchment scale and limited by coarse resolution data. This understanding is required to target mitigation measures and to provide a framework to monitor their effectiveness.

Approaches to herbicide (MCPA) pollution mitigation in drinking water source catchments using enhanced space and time monitoring.

Freshwater occurrences of the selective acid herbicide 2-methyl-4-chloro-phenoxyacetic acid (MCPA) are an ongoing regulatory and financial issue for water utility industries as the number and magnitude of detections increase, particularly in surface water catchments. Assessments for mitigating pesticide pollution in catchments used as drinking water sources require a combination of catchment-based and water treatment solutions, but approaches are limited by a lack of empirical data. In this study, an enhanced spatial (11 locations) and temporal (7-hourly to daily sampling) monitoring approach was employed to address these issues in an exemplar surface water source catchment (384 km).

Vegetation matters: Correcting chamber carbon flux measurements using plant volumes.

Chamber carbon flux measurements are routinely used to assess ecosystem carbon sink/source dynamics. Often these point measurements enclose considerable vegetation biomass, with fluxes upscaled in space and time for each vegetation type. Here we assess the importance of including the volume of peatland dwarf shrub vegetation in chamber flux calculations and outline a simple but effective method of assessing plant volumes.