Linking Hydro-Geophysics and Remote Sensing Technology for Sustainable Water and Agricultural Catchment Management

PosterThe acquisition of sub-surface data for agricultural purposes is traditionally achieved by in situ point sampling in the top 2m over limited target areas (farm scale ~ km2) and time periods. This approach is inadequate for integrated regional (water catchment ~ 100 km2) scale management strategies which require an understanding of processes varying over decadal time scales in the transition zone (~ 10’s m) from surface to bedrock. With global food demand expected to increase by 100% by 2050, there are worldwide concerns that achievement of production targets will be at the expense of water quality. In order to overcome the limitations of the traditional approach, this research programme will combine airborne and ground geophysics with remote sensing technologies to access hydrogeological and soil structure information on Irish Soils at multiple spatial scales. It will address this problem in the context of providing tools for the sustainable management of agricultural intensification envisioned in Food Harvest 2020 and Food Wise 2025 and considering the EU Habitats and Water Framework Directives (WFD), Clean Air Policy and Soil Thematic Strategies. The work will use existing ground based geophysical and hydrogeological data from Teagasc Agricultural Catchment Programme (ACP) and Heavy Soil sites co-located ground and airborne electromagnetic data. Neural Networks training and Machine learning approaches will supplement traditional geophysical workflows. Work will then focus on upscaling results from ACP to WFD catchment scale. This upscaling will require modification of traditional satellite remote sensing conceptual frameworks to analyse heterogeneous, multi-temporal data streams

Using a multi-dimensional approach for catchment scale herbicide pollution assessments

peer-reviewedWorldwide herbicide use in agriculture, whilst safeguarding yields also presents water quality issues. Controlling factors in agricultural catchments include both static and dynamic parameters. The present study investigated the occurrence of herbicides in streams and groundwater in two meso-scale catchments with contrasting flow controls and agricultural landuse (grassland and arable land). Using a multi-dimensional approach, streams were monitored from November 2018 to November 2019 using Chemcatcher® passive sampling devices and groundwater was sampled in 95 private drinking water wells. The concentrations of herbicides were larger in the stream of the Grassland catchment (8.9–472.6 ng L−1) dominated by poorly drained soils than in the Arable catchment (0.9–169.1 ng L−1) dominated by well-drained soils. Incidental losses of herbicides during time of application and low flows in summer caused concentrations of MCPA, Fluroxypyr, Trichlorpyr, Clopyralid and Mecoprop to exceeded the European Union (EU) drinking water standard due to a lack of dilution. Herbicides were present in the stream throughout the year and the total mass load was higher in winter flows, suggesting a persistence of primary chemical residues in soil and sub-surface environments and restricted degradation. Losses of herbicides to the streams were source limited and influenced by hydrological conditions. Herbicides were detected in 38% of surveyed drinking water wells. While most areas had concentrations below the EU drinking water standard some areas with well-drained soils in the Grassland catchment, had concentrations exceeding recommendations. Individual wells had concentrations of Clopyralid (619 ng L−1) and Trichlorpyr (650 ng L−1). Despite the study areas not usually associated with herbicide pollution, and annual mass loads being comparatively low, many herbicides were present in both surface and groundwater, sometimes above the recommendations for drinking water. This whole catchment assessment provides a basis to develop collaborative measures to mitigate pollution of water by herbicides.Horizon 2020 Framework Programm

A new sensitive method for the simultaneous chromatographic separation and tandem mass spectrometry detection of anticoccidials, including highly polar compounds, in environmental waters

peer-reviewedA sensitive and selective method was developed and validated for the determination of 26 anticoccidial compounds (six ionophores and twenty chemical coccidiostats) in surface and groundwater samples at parts-per-quadrillion (pg L−1) to parts-per-trillion (ng L−1) levels by ultra-high performance liquid chromatography with tandem mass spectrometry detection (UHPLC–MS/MS). A range of different analytical columns and mobile phase compositions were evaluated to enhance selectivity and retention of a number of highly polar and basic anticoccidials along with other non-polar coccidiostats. A combined separation, including these problematic polar compounds, was achieved on a phenyl-hexyl column, by binary gradient elution with water/acetonitrile using ammonium formate and formic acid as additives. The anticoccidial residues were extracted from raw, unfiltered, water samples (250 mL) using polymeric divinylbenzene solid phase extraction (SPE) cartridges, with subsequent elution (methanol:acetonitrile:ethyl acetate, 40:40:20, v/v) and concentration prior to determination. The method recovery (at a concentration representative of realistic expected environmental water concentrations based on literature review) ranged from 81% to 105%. The method was successfully validated for 26 anticoccidials, at four concentration levels, in accordance to Commission Decision 2002/657/EC and SANTE/11813/2017 guidelines. Trueness and precision, under within-laboratory reproducibility conditions, ranged from 88% to 111% and 0.9% to 10.3% respectively

Real-time forecasting of pesticide concentrations in soil

peer-reviewedForecasting pesticide residues in soils in real time is essential for agronomic purposes, to manage phytotoxic effects, and in catchments to manage surface and ground water quality. This has not been possible in the past due to both modelling and measurement constraints. Here, the analytical transient probability distribution (pdf) of pesticide concentrations is derived. The pdf results from the random ways in which rain events occur after pesticide application. First-order degradation kinetics and linear equilibrium sorption are assumed. The analytical pdfs allow understanding of the relative contributions that climate (mean storm depth and mean rainfall event frequency) and chemical (sorption and degradation) properties have on the variability of soil concentrations into the future. We demonstrated the two uncertain reaction parameters can be constrained using Bayesian methods. An approach to a Bayesian informed forecast is then presented. With the use of new rapid tests capable of providing quantitative measurements of soil concentrations in the field, real-time forecasting of future pesticide concentrations now looks possible for the first time. Such an approach offers new means to manage crops, soils and water quality, and may be extended to other classes of pesticides for ecological risk assessment purposes

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

Publication history: Accepted - 21 May 2022; Published online - 24 May 2022.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.This work was carried out as part of Source to Tap (IVA5018), a project supported by the European Union’s INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB)

Field scale phosphorus balances and legacy soil pressures in mixed-land use catchments

peer-reviewedReducing legacy soil phosphorus (P) is recognised as an effective measure to mitigate diffuse P losses from agricultural landscapes and alleviate trophic pressure to freshwaters systems. Accounting for the distribution of P within farms is critical in identifying fields of agronomic underperformance and/or environmental risk to water as a consequence of inadequately managed re-cycling of P. There is also a need to understand how P use and legacy soil P evolves under the Nitrates Action Programme (NAP) regulations from the European Union (EU) Nitrates Directive. In an Irish case study the aim was to provide a systematic and detailed audit of P balance and soil P responses and trends in two mixed land use agricultural catchments (Arable A and B) across a four year study period. Driven by increased mineral P inputs the field balances in the Arable A catchment had an average surplus P, ranging from 1.9 to 7.5 kg ha−1 yr−1. However, between the study period 2010 to 2013, the average soil test P (STP) levels declined, with the area of excessive soil P concentrations decreasing by 8%. Similarly, in the Arable B catchment the average annual P inputs increased the surplus field P from -0.42 to 25.5 kg ha−1 yr−1, but the area of excessive soil P concentrations increased by 4%. In part, this increase is attributed to some fields receiving excess applications of organic nutrient forms above crop requirements. Whilst, the legacy soil P declined in the Arable A catchment indicating a response to NAP, for both catchments it is evident that the distribution of P sources within farms was poor and P inputs often did not match crop and soil P requirements at the field scale. This study highlights the need for improved support to knowledge transfer mechanisms that can deliver better farm and soil specific nutrient management planning strategies. Without this consideration, achieving the dual benefits of improvement to water quality and increased crop output from agricultural landscapes will be restricted.Department of Agricultural, Food and the Marine in Irelan

Phthaloylchitosan-Based Gel Polymer Electrolytes for Efficient Dye-Sensitized Solar Cells

Phthaloylchitosan-based gel polymer electrolytes were prepared with tetrapropylammonium iodide, Pr 4 NI, as the salt and optimized for conductivity. The electrolyte with the composition of 15.7 wt.% phthaloylchitosan, 31.7 wt.% ethylene carbonate (EC), 3.17wt.% propylene carbonate (PC), 19.0 wt.% of Pr 4 NI, and 1.9wt.% iodine exhibits the highest room temperature ionic conductivity of 5.27 x 10 -3 S cm -1. The dye-sensitized solar cell (DSSC) fabricated with this electrolyte exhibits an efficiency of 3.5% with.. SC of 7.38mAcm -2,.. OC of 0.72V, and fill factor of 0.66. When various amounts of lithium iodide (LiI) were added to the optimized gel electrolyte, the overall conductivity is observed to decrease. However, the efficiency of the DSSC increases to a maximum value of 3.71% when salt ratio of Pr 4 NI : LiI is 2 : 1. This cell has.. SC,.. OC and fill factor of 7.25mAcm -2, 0.77V and 0.67, respectively

Integrated climate-chemical indicators of diffuse pollution from land to water

Management of agricultural diffuse pollution to water remains a challenge and is influenced by the complex interactions of rainfall-runoff pathways, soil and nutrient management, agricultural landscape heterogeneity and biogeochemical cycling in receiving water bodies. Amplified cycles of weather can also influence nutrient loss to water although they are less considered in policy reviews. Here, we present the development of climate-chemical indicators of diffuse pollution in highly monitored catchments in Western Europe. Specifically, we investigated the influences and relationships between weather processes amplified by the North Atlantic Oscillation during a sharp upward trend (20102016) and the patterns of diffuse nitrate and phosphorus pollution in rivers. On an annual scale, we found correlations between local catchment-scale nutrient concentrations in rivers and the influence of larger, oceanic-scale climate patterns defined by the intensity of the North Atlantic Oscillation. These influences were catchment-specific showing positive, negative or no correlation according to a typology. Upward trends in these decadal oscillations may override positive benefits of local management in some years or indicate greater benefits in other years. Developing integrated climate-chemical indicators into catchment monitoring indicators will provide a new and important contribution to water quality management objectives