Pesticide Use in Bangladesh: A Review on Potential Impacts

Bangladesh is a densely populated agricultural country. A wide range of products of pesticides being used in Bangladesh is already considered a health and environmental concern by different international agencies including the World Health Organization (WHO). Excessive, irrational use of pesticides in agriculture, and lack of knowledge on pest management have caused widespread pesticide pollution which is now posing a substantial threat to the environment and local people. In this review, we assessed and analyzed previous literature systematically to map a complete scenario of pesticide pollution in Bangladesh, covering soil, water, and foods. Most of the previous studies indicated that soil, water, and different seasonal vegetables are contaminated with organophosphorus, pyrethroid, and exceeded the FAO/WHO maximum residual limits. Concentration of chlorpyriphos, malathion were found below the detection limit in soil samples. But water samples were found contaminated with chlorpyrifos, diazinon, malathion, carbaryl and carbofuran. Considered vegetable samples were adulterated with fenvalerate, quinalphos, cypermethrin, fenitrothion, dimethoate, parathion, linuron, phenthoate. Persistence of organochlorines in the environment is limited and meets the maximum residue level (MRLs). This study will help to depict the pesticide pollution status in the environmental matrices in recent years and to cut off the exacerbation of pesticide pollution. A proactive approach is essential to limit the pesticide pollution load in the environmental matrices.

Occurrence of Pesticides Associated with an Agricultural Drainage System in a Mediterranean Environment

Surface water pollution (as a result of pesticides) is a major problem, due to the negative impact on human health and ecosystems. The excessive use and persistence of surface water pollution in the environment may present a notable risk. In this article, DDT and its metabolite DDE hereafter, DDT–DDE), and a commonly used pesticide (herbicide) glyphosate, were analyzed in agricultural drainage waters; afterward, a spatial analysis was applied to identify potential areas of high pesticide occurrence in an agricultural Mediterranean coastal floodplain. The spatial distribution of banned (Directive 79/117/EEC), yet highly persistent pesticides in the environment, such as DDT (and metabolites), was compared with the (currently and mostly used) glyphosate. A sequence of various point patterns, spatial analysis methods, and non-parametric statistics, were computed to elucidate the pesticide pollution hotspots. As a reference value, almost 70% of the water samples were above the World Health Organization (WHO) guideline for DDT (and metabolites) for drinking water (1 µg/L), with a maximum of 6.53 µg/L. Our spatial analysis approach revealed a significantly high concentration of DDT–DDE clusters close to wetlands in natural parks, where mosquitos are abundant, and pesticides persist and flow to the surface waters from soil and groundwater pools. Conversely, glyphosate concentrations were below WHO guidelines; their spatial patterns were related more toward current agricultural uses in the southern sector of the study area.

Evaluation of Farmers satisfaction with Ecological Governance and its improvement path

As the participants and stakeholders of rural ecological governance, the evaluation of farmers’ satisfaction plays an important role in improving the performance of government ecological governance. Based on the criteria of ecological civilization construction and customer satisfaction, this paper constructs an evaluation system of farmers’ ecological governance satisfaction, which includes 34 indicators. Factor analysis is used to classify indicators, and IPA model is used to analyze the ecological governance plates that affect satisfaction. The research shows that the comprehensive satisfaction of rural ecological governance farmers in four towns of Changde City, Hunan Province is 3.6, which is basically recognized by farmers. The factors that farmers’ demand is strong but does not meet the expectations are sewage treatment, chemical fertilizer and pesticide pollution treatment, ecological legal system implementation, government investment and other indicators. The evaluation section of restriction satisfaction mainly focuses on ecological environment, institutional culture and infrastructure, and finally puts forward suggestions from three aspects: ecological environment, infrastructure and farmers’ sense of participation.

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

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.

Application of Compound-Specific Isotope Analysis in Environmental Forensic and Strategic Management Avenue for Pesticide Residues

Unintended pesticide pollution in soil, crops, and adjacent environments has caused several issues for both pesticide users and consumers. For users, pesticides utilized should provide higher yield and lower persistence while considering both the environment and agricultural products. Most people are concerned that agricultural products expose humans to pesticides accumulating in vegetation. Thus, many countries have guidelines for assessing and managing pesticide pollution, for farming in diverse environments, as all life forms in soil are untargeted to these pesticides. The stable isotope approach has been a useful technique to find the source of organic matter in studies relating to aquatic ecology and environmental sciences since the 1980s. In this study, we discuss commonly used analytical methods using liquid and gas chromatography coupled with isotopic ratio mass spectrometry, as well as the advanced compound-specific isotope analysis (CSIA). CSIA applications are discussed for tracing organic pollutants and understanding chemical reactions (mechanisms) in natural environments. It shows great applicability for the issues on unintended pesticide pollution in several environments with the progress history of isotope application in agricultural and environmental studies. We also suggest future study directions based on the forensic applications of stable isotope analysis to trace pesticides in the environment and crops.