scholarly journals Probabilistic modelling of inherent field-level pesticide pollution risk in a small drinking water catchment using spatial Bayesian Belief Networks

2021 ◽  
Author(s):  
Mads Troldborg ◽  
Zisis Gagkas ◽  
Andy Vinten ◽  
Allan Lilly ◽  
Miriam Glendell

Abstract. Pesticides are contaminants of priority concern that continue to present a significant risk to drinking water quality. While pollution mitigation in catchment systems is considered a cost-effective alternative to costly drinking water treatment, the effectiveness of pollution mitigation measures is uncertain and needs to be able to consider local biophysical, agronomic, and social aspects. We developed a probabilistic decision support tool (DST) based on spatial Bayesian Belief Networks (BBN) that simulates inherent pesticide leaching risk to ground- and surface water quality to inform field-level pesticide mitigation strategies in a small drinking water catchment (3.1 km2) with limited observational data. The DST accounts for the spatial heterogeneity in soil properties, topographic connectivity, and agronomic practices; temporal variability of climatic and hydrological processes as well as uncertainties related to pesticide properties and the effectiveness of management interventions. The rate of pesticide loss via overland flow and leaching to groundwater and the resulting risk of exceeding a regulatory threshold for drinking water was simulated for five active ingredients. Risk factors included climate and hydrology (temperature, rainfall, evapotranspiration, overland and subsurface flow), soil properties (texture, organic matter content, hydrological properties), topography (slope, distance to surface water/depth to groundwater), land cover and agronomic practices, pesticide properties and usage. The effectiveness of mitigation measures such as delayed timing of pesticide application; 10 %, 25 % and 50 % reduction in application rate; field buffers; and presence/absence of soil pan on risk reduction were evaluated. Sensitivity analysis identified the month of application, land use, presence of buffers, field slope and distance as the most important risk factors, alongside several additional influential variables. Pesticide pollution risk from surface water runoff showed clear spatial variability across the study catchment, while groundwater leaching risk was uniformly low, with the exception of prosulfocarb. Combined interventions of 50 % reduced pesticide application rate, management of plough pan, delayed application timing and field buffer installation notably reduced the probability of high-risk from overland runoff and groundwater leaching, with individual measures having a smaller impact. The graphical nature of the BBN facilitated interactive model development and evaluation with stakeholders to build model credibility, while the ability to integrate diverse data sources allowed a dynamic field-scale assessment of ‘critical source areas’ of pesticide pollution in time and space in a data scarce catchment, with explicit representation of uncertainties.

2021 ◽  
Author(s):  
Miriam Glendell ◽  
Mads Troldborg ◽  
Zisis Gagkas ◽  
Andy Vinten ◽  
Allan Lilly ◽  
...  

<p>Pesticides are contaminants of priority concern regulated under the EU Water Framework Directive 2000 (WFD) and its daughter Directives. Article 7 of the WFD promotes a ‘prevention-led’ approach that prioritises pollution prevention at source rather than costly drinking water treatment.</p><p>However, the effectiveness of pollution mitigation measures in catchment systems is uncertain and catchment management needs to consider local biophysical, agronomic, and social aspects. Local risk assessment and management of water contamination in drinking water catchments informed by process-based models is costly and often hindered by lack of data. Therefore, spatial risk indices have been developed to evaluate the intrinsic risk from pesticide pollution. However, these risk assessment approaches do not explicitly account for uncertainties in complex processes and their interactions. </p><p>In this study, we developed a probabilistic decision support tool (DST) based on spatial Bayesian Belief Networks (BBN) to inform field-level pesticide mitigation strategies in a small drinking water catchment (3.5 km<sup>2</sup>) with limited observational data. The DST accounts for the spatial heterogeneity of soil properties, topographic connectivity, and agronomic practices; temporal variability of climatic and hydrological processes as well as uncertainties related to pesticide properties and the effectiveness of management interventions. Furthermore, the graphical nature of the BBN facilitated interactive model development and evaluation with stakeholders, while the ability to integrate diverse data sources allowed an effective use of available data.</p><p>The risk of pesticide loss via two pathways (overland flow and leaching to groundwater) was simulated for five active ingredients. Risk factors included climate and hydrology (temperature, rainfall, evapotranspiration, overland and subsurface flow), soil properties (texture, organic matter content, hydrological properties), topography (slope, distance to surface water/depth to groundwater), landcover and agronomic practices, pesticide properties and usage. The effectiveness of mitigation measures such as delayed pesticide application timing; 10%, 25% and 50% application rate reduction; field buffers; and presence/absence of soil pan on risk reduction were evaluated.</p><p>Sensitivity analysis identified the application rates, rainfall, and overland flow connectivity as the most important risk factors. Pesticide pollution risk from surface water runoff showed clear spatial variability across the study catchment, while groundwater leaching risk was more uniform. Combined interventions of 50% reduced pesticide application rate, management of plough pan, delayed application timing and field buffer installation reduced the probability of high-risk from overland flow in several fields.</p><p>The DST provided a probabilistic dynamic field-scale assessment of ‘critical risk areas’ of pesticide pollution in time and space and is easily transferable to neighbouring catchments.</p>


2020 ◽  
Author(s):  
Piet Seuntjens ◽  
Ellen Pauwelyn ◽  
Els Belmans ◽  
Ingeborg Joris ◽  
Elien Dupon ◽  
...  

<p>High-quality, safe, and sufficient drinking water is essential for life: we use it for drinking, food preparation and cleaning. Agriculture is the biggest source of pesticides and nitrate pollution in European fresh waters. Pesticide occurrences in rivers result from diffuse runoff from farmland or from point sources from the farmyard. Although many best management practices (BMPs) to mitigate these diffuse and point sources are developed and widely disseminated for several years, the effective implementation of mitigation measures in practice remains limited. Therefore, the Waterprotect project has been set up to improve the knowledge and awareness of the impact of crop protection products on the water quality among the many actors, to identify the bottlenecks for implementation of suitable BMPs and further develop new governance strategies to overcome these issues for a more effective drinking water protection. As all actors share the responsibility to deal with the water quality, government agencies (e.g. environmental agencies), private actors (e.g. drinking water company, input supplier, processing industry) and civil society actors (e.g. farmers) are involved in the project. Processes to cope with the problem are initiated in 7 action labs among which the Belgian Bollaertbeek action lab. The study area is a small agricultural catchment where surface water is used as intake to produce drinking water for the nearby city. The area is sensitive to erosion and based on a physical analysis and risk analysis of the catchment, the implementation of filling and cleaning places on individual farms and buffer strips along the watercourse are proposed as suitable measures to tackle the pollution problem. In order to implement them, mechanisms to increase the involvement of targeted farmers and alternative governance systems are studied. Results of the analysis of the water quality issues and the water governance system in the Belgian Bollaertbeek action lab and the strategies to try to improve the uptake of mitigation measures to improve water quality will be presented.</p>


2020 ◽  
Author(s):  
Vaida Suslovaite ◽  
James Shucksmith ◽  
Vanessa Speight

<p>Diffuse pollution resulting from rainfall runoff processes is known to adversely affect surface water quality, including in areas where surface water is used for drinking water supply. Designing and implementing targeted mitigation measures to reduce peak concentrations of specific contaminants such as pesticides is challenging due to the spatial and temporal variability of rainfall-runoff processes. Receiving water pollutant concentrations are a function of rainfall processes, catchment characteristics, receiving water conditions and the locations of pollution sources (i.e. spatial distribution of ‘high risk’ land use types). Past work has developed a validated, travel time based, physically distributed model used to predict metaldehyde levels after a rainfall event accounting for variations in rainfall and distribution of land use. However, targeted field scale mitigation measures require an understanding of how different land use distributions affect pollutant concentrations in river water over a representative number of rainfall events. </p><p>In this study, an inverse modelling approach is adopted in which the metaldehyde model is used in conjunction with spatial and temporal distributions of rainfall data spanning over a number of years. Genetic algorithm(GA) technique is used to carry out land use optimisation. This technique can be used to determine distributions of land use that minimises the total number of predicted hours that metaldehyde levels exceed the EU and UK threshold of 0.1 μg L−1 for pesticides in drinking water. The approach can also be used to show how the removal of specific high risk fields will affect metaldehyde concentrations as well as rank and prioritise specific catchment areas. This can be used to inform catchment management groups of the most effective locations for the implementation of mitigation measures.</p>


2003 ◽  
Vol 3 (5-6) ◽  
pp. 15-22
Author(s):  
P. Kouadio ◽  
M. Tétrault

Three colored surface water nanofiltration pilot-scale projects were conducted in the province of Quebec (eastern Canada), between November 2000 and March 2002, by the company H2O Innovation (2000) inc., for the municipalities of Lac Bouchette, Latulipe-et-Gaboury and Charlesbourg (now part of Quebec City). Results indicated that nanofiltration permeate quality has an advance on present drinking water regulation standard in Quebec, but important membrane fouling occurred. Fouling can be controlled by pretreatment and optimization of the operating conditions.


2006 ◽  
Vol 6 (2) ◽  
pp. 47-53 ◽  
Author(s):  
D. Simazaki ◽  
M. Asami ◽  
T. Nishimura ◽  
S. Kunikane ◽  
T. Aizawa ◽  
...  

Nationwide surveys of 1,4-dioxane and methyl-t-butyl ether (MTBE) levels in raw water used for the drinking water supply were conducted at 91 water treatment plants in Japan in 2001 and 2002, prior to the revision of the drinking water quality standards. 1,4-dioxane was widely and continuously detected in raw water samples and its occurrence was more frequent and its concentrations higher in groundwater than in surface water. However, its maximum concentration in raw water was much lower than its new standard value (50 μg/L), which was determined as a level of 10−5 excessive cancer risk to humans. Trace levels of MTBE were also detected in several surface water samples.


1994 ◽  
Vol 30 (10) ◽  
pp. 221-227 ◽  
Author(s):  
Jordi Martín-Alonso

The Llobregat is a 156 km long river, which supplies 35% of the Barcelona's drinking water needs from the Sant Joan Despí Water Treatment Plant. Since the establishment of the Salt Mine Works in the Llobregat basin in 1923, a progressive salinization of the water sources has been recorded. The operation of the Brine Collector, as a public work carried out by Aigües de Barcelona (AGBAR), started in 1989; it enabled a very significant improvement in the quality of the surface water used for drinking-water production.


2017 ◽  
Author(s):  
Klaus Neumann ◽  
◽  
Kirsten N. Nicholson ◽  
Carolyn B. Dowling ◽  
Leah Wood ◽  
...  

Biochar ◽  
2021 ◽  
Author(s):  
Ngitheni Winnie-Kate Nyoka ◽  
Ozekeke Ogbeide ◽  
Patricks Voua Otomo

AbstractTerrestrial and aquatic ecosystems are increasingly threatened by pesticide pollution resulting from extensive use of pesticides, and due to the lack of regulatory measures in the developing world, there is a need for affordable means to lessen environmental effects. This study aimed to investigate the impact of biochar amendment on the toxicity of imidacloprid to life-cycle parameters and biomarker responses of the earthworm Eisenia fetida. E. fetida was exposed to 10% biochar-amended and non-amended OECD artificial soils spiked with 0, 0.75, 1.5, 2.25 and 3 mg imidacloprid/kg for 28 days. An LC50 of 2.7 mg/kg was only computed in the non-amended soil but not in the biochar-amended soil due to insignificant mortality. The EC50 calculated in the non-amended soil (0.92 mg/kg) for reproduction (fertility) was lower than the one computed in the biochar amended (0.98 mg/kg), indicating a decrease in toxicity in the biochar-amended substrate. Significant weight loss was observed at the two highest imidacloprid treatments in the non-amended soil and only at the highest treatment in the biochar-amended substrate, further highlighting the beneficial effects of biochar. Catalase activity decreased significantly at the two highest concentrations of non-amended soil. Yet, in the amended soil, the activity remained high, especially in the highest concentration, where it was significantly higher than the controls. This indicated more severe oxidative stress in the absence of biochar. In all non-amended treatments, there was a significant acetylcholinesterase inhibition, while lower inhibition percentages were observed in the biochar-amended soil. In most endpoints, the addition of biochar alleviated the toxic effects of imidacloprid, which shows that biochar has the potential to be useful in soil remediation. However, there is still a need for field studies to identify the most effective application rate of biochar for land application.


2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Ananda Tiwari ◽  
Anna-Maria Hokajärvi ◽  
Jorge Santo Domingo ◽  
Michael Elk ◽  
Balamuralikrishna Jayaprakash ◽  
...  

Abstract Background Rivers and lakes are used for multiple purposes such as for drinking water (DW) production, recreation, and as recipients of wastewater from various sources. The deterioration of surface water quality with wastewater is well-known, but less is known about the bacterial community dynamics in the affected surface waters. Understanding the bacterial community characteristics —from the source of contamination, through the watershed to the DW production process—may help safeguard human health and the environment. Results The spatial and seasonal dynamics of bacterial communities, their predicted functions, and potential health-related bacterial (PHRB) reads within the Kokemäenjoki River watershed in southwest Finland were analyzed with the 16S rRNA-gene amplicon sequencing method. Water samples were collected from various sampling points of the watershed, from its major pollution sources (sewage influent and effluent, industrial effluent, mine runoff) and different stages of the DW treatment process (pre-treatment, groundwater observation well, DW production well) by using the river water as raw water with an artificial groundwater recharge (AGR). The beta-diversity analysis revealed that bacterial communities were highly varied among sample groups (R = 0.92, p <  0.001, ANOSIM). The species richness and evenness indices were highest in surface water (Chao1; 920 ± 10) among sample groups and gradually decreased during the DW treatment process (DW production well; Chao1: 320 ± 20). Although the phylum Proteobacteria was omnipresent, its relative abundance was higher in sewage and industrial effluents (66–80%) than in surface water (55%). Phyla Firmicutes and Fusobacteria were only detected in sewage samples. Actinobacteria was more abundant in the surface water (≥13%) than in other groups (≤3%). Acidobacteria was more abundant in the DW treatment process (≥13%) than in others (≤2%). In total, the share of PHRB reads was higher in sewage and surface water than in the DW treatment samples. The seasonal effect in bacterial communities was observed only on surface water samples, with the lowest diversity during summer. Conclusions The low bacterial diversity and absence of PHRB read in the DW samples indicate AGR can produce biologically stable and microbiologically safe drinking water. Furthermore, the significantly different bacterial communities at the pollution sources compared to surface water and DW samples highlight the importance of effective wastewater treatment for protecting the environment and human health.


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