Browsing by Author "Jordan, Phil"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Assessments of Composite and Discrete Sampling Approaches for Water Quality Monitoring
    (Springer, 2018-04-12) Cassidy, Rachel; Jordan, Phil; Bechmann, Marianne; Kronvang, Brian; Kyllmar, Katarina; Shore, Mairead
    Achieving an operational compromise between spatial coverage and temporal resolution in national scale river water quality monitoring is a major challenge for regulatory authorities, particularly where chemical concentrations are hydrologically dependent. The efficacy of flow-weighted composite sampling (FWCS) approaches for total phosphorus (TP) sampling (n = 26–52 analysed samples per year), previously applied in monitoring programmes in Norway, Sweden and Denmark, and which account for low to high flow discharges, was assessed by repeated simulated sampling on high resolution TP data. These data were collected in three research catchments in Ireland over the period 2010–13 covering a base-flow index range of 0.38 to 0.69. Comparisons of load estimates were also made with discrete (set time interval) daily and sub-daily sampling approaches (n = 365 to >1200 analysed samples per year). For all years and all sites a proxy of the Norwegian sampling approach, which is based on re-forecasting discharge for each 2-week deployment, proved most stable (median TP load estimates of 87–98%). Danish and Swedish approaches, using long-term flow records to set a flow constant, were only slightly less effective (median load estimates of 64–102% and 80–96%, respectively). Though TP load estimates over repeated iterations were more accurate using the discrete approaches, particularly the 24/7 approach (one sample every 7 h in a 24 bottle sampler - median % load estimates of 93–100%), composite load estimates were more stable, due to the integration of multiple small samples (n = 100–588) over a deployment.
  • Thumbnail Image
    Item
    A carrying capacity framework for soil phosphorus and hydrological sensitivity from farm to catchment scales
    (Elsevier, 2019-06-04) Cassidy, Rachel; Thomas, Ian A.; Higgins, Alex J.; Bailey, John S.; Jordan, Phil
    Agricultural fieldswith above optimumsoil phosphorus (P) are considered to pose risks to water quality and especially when those areas are coincident with hydrologically sensitive areas (HSAs) that focus surface runoff pathways. This is a challenge tomanage in areas of agricultural intensity in surfacewater dominated catchments where water quality targets have to be met. In this study, a soil P survey of 13 sub-catchments and 7693 fields was undertaken in a 220 km2 catchment. HSAs were also determined as the top 25th percentile risk froma runoff routingmodel that used a LiDAR digital elevation model and soil hydraulic conductivity properties. Distributions of these spatial data were compared with river soluble reactive phosphorus (SRP) concentration measured fortnightly over one year. The results showed that 41% of fields exceeded the agronomic optimumfor soil P across the sub-catchments.When compared with the available water quality data, the results indicated that the high soil P carrying capacity area of the sub-catchmentswas 15%. Combining high soil P and HSA, the carrying capacity area of the sub-catchmentswas 1.5%. The opportunities to redistribute these riskswere analysed on fields with below optimum soil P and where HSA risk was also minimal. These ranged from 0.4% to 13.8% of sub-catchment areas and this limited potential, unlikely to fully reduce the P pressure to over-supplied fields, would need to be considered alongside addressing this over-supply and also with targeted HSA interception measures.
  • Thumbnail Image
    Item
    Perspectives on water quality monitoring approaches for behavioural change research
    (Frontiers Media, 2022-07-01) Jordan, Phil; Cassidy, Rachel
    This review considers enhanced approaches to river water quality monitoring in north-western Europe following a series of study visits (11 sites in 7 countries). Based on the evidence gathered, options were identified and evaluated for their suitability to deliver specific water quality monitoring objectives and with a focus on effecting behavioral change. Monitoring programs were diverse, ranging from enhanced grab sampling and laboratory analysis to sub-hourly sampling of multiple parameters and nutrients in autonomous high-specification, bank-side or mobile laboratories. Only one program out of all the cases evaluated could readily identify influences that had produced behavioral change among stakeholders. This was principally because the other programs were focused on top-down policy change or surveillance rather than specifically focused on influencing behavior. Nevertheless, program researchers were clear that stakeholder engagement potential was very high and that the sites acted as important focus points for discussion on water quality issues, and so part of a suite of tools that might ultimately change behavior. This identifies a space where water quality monitoring solutions could be adapted for behavioral change research.
  • Thumbnail Image
    Item
    Quantifying MCPA load pathways at catchment scale using high temporal resolution data
    (Elsevier, 2022-05-24) Atcheson, Kevin; Mellander, Per-Erik; Cassidy, Rachel; Cook, Sally; Floyd, Stewart; McRoberts, Colin; Morton, Phoebe; Jordan, Phil
    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. To address this knowledge gap, this study reports findings from river discharge and synchronous MCPA concentration datasets (continuous 7 hour and with additional hourly sampling during storm events) collected over a 7 month herbicide spraying season. The study was undertaken in a surface (source) water catchment (384 km2—of which 154 km2 is agricultural land use) in the cross-border area of Ireland. Combined into loads, and using two pathway separation techniques, the MCPA data were apportioned into event and baseload components and the former was further separated to quantify a quickflow (QF) and other event pathways. Based on the 7 hourly dataset, 85.2 kg (0.22 kg km􀀀 2 by catchment area, or 0.55 kg km􀀀 2 by agricultural area) of MCPA was exported from the catchment in 7 months. Of this load, 87.7 % was transported via event flow pathways with 72.0 % transported via surface dominated (QF) pathways. Approximately 12 % of the MCPA load was transported via deep baseflows, indicating a persistence in this delayed pathway, and this was the primary pathway condition monitored in a weekly regulatory sampling programme. However, overall, the data indicated a dominant acute, storm dependent process of incidental MCPA loss during the spraying season. Reducing use and/or implementing extensive surface pathway disconnection measures are the mitigation options with greatest potential, the success of which can only be assessed using high temporal resolution monitoring techniques.
  • Thumbnail Image
    Item
    Quantifying nutrient and sediment erosion at riverbank cattle access points using fine-scale geo-spatial data
    (Elsevier, 2023-10-14) Scott, Alison; Cassidy, Rachel; Arnscheidt, Joerg; Rogers, David; Jordan, Phil; Environmental Protection
    Unrestricted cattle access to the riparian zone can exacerbate riverbank erosion in grazed grassland catchments. Knowledge gaps include the magnitude of erosion and other environmental pressures at cattle access points. This study aimed to address this by using two high resolution geo-spatial methods; 1) aerial photogrammetry and 2) terrestrial laser scanning to measure cumulative, seasonal, and annual erosion rates at nine unmitigated cattle access points in Northern Ireland. Total, fine sediment and total phosphorus exports were determined through bulk density and deep soil core sampling campaigns of exposed bank faces. Accumulated erosion was estimated using method 1) at 1.0 – 49.5 t and 0.51 – 16.64 kg for total sediment and total phosphorus, respectively. Using method 2) median annual export coefficients of 0.19 – 0.21 t m−1 and 0.065 – 0.087 kg m−1 (normalised to streambank length) were determined for total sediment and total phosphorus transfers respectively and these mostly occurred during the grazing season (median 84% for both sediment and total phosphorus). In terms of livestock pressures, these annual exports equate to 0.34 – 0.40 t LU-1 yr−1 and 0.103 – 0.111 kg LU-1 yr−1 for total sediment and total phosphorus, respectively (1.19–1.89 LU ha−1). The conventional measure of protective fencing is likely to prevent such transfers to rivers. Scaling a nationwide agri-environment scheme over six years which installed 2,493 km of riparian fencing (and assuming from this study that 1.9 % of all riparian field boundaries had cattle access impact), this measure potentially saved 9,047–9,999 t yr−1 and 3,095 – 4,143 kg yr−1 of total sediment and total phosphorus, respectively, from entering water courses.
  • Thumbnail Image
    Item
    Reducing MCPA herbicide pollution at catchment scale using an agri-environmental scheme
    (Elsevier, 2022-05-20) Cassidy, Rachel; Jordan, Phil; Farrow, Luke; Floyd, Stewart; McRoberts, Colin; Morton, Phoebe; Doody, Donnacha
    In river catchments used as drinking water sources, high pesticide concentrations in abstracted waters require an expensive treatment step prior to supply. The acid herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) is particularly problematic as it is highly mobile in the soil-water environment following application. Here, an agri-environmental scheme (AES) was introduced to a large-scale catchment (384 km2) to potentially reduce the burden of pesticides in the water treatment process. The main measure offered was contractor application of glyphosate by weed wiping as a substitute for boom spraying of MCPA, supported by educational and advisory activities. A combined innovation applied in the assessment was, i) a full before-after-control-impact (BACI) framework over four peak application seasons (April to October 2018 to 2021) where a neighbouring catchment (386 km2) did not have an AES and, ii) an enhanced monitoring approach where river discharge and MCPA concentrations were measured synchronously in each catchment. During peak application periods the sample resolution was every 7 h, and daily during quiescent winter periods. This sampling approach enabled flow- and time-weighted concentrations to be established, and a detailed record of export loads. These loads were up to 0.242 kg km−2 yr−1, and over an order of magnitude higher than previously reported in the literature. Despite this, and accounting for inter-annual and seasonal variations in river discharges, the AES catchment indicated a reduction in both flow- and time-weighted MCPA concentration of up to 21% and 24%, respectively, compared to the control catchment. No pollution swapping was detected. Nevertheless, the percentage of MCPA occurrences above a 0.1 μg L−1 threshold did not reduce and so the need for treatment was not fully resolved. Although the work highlights the advantages of catchment management approaches for pollution reduction in source water catchments, it also indicates that maximising participation will be essential for future AES.