National assessment of spatiotemporal loss in agricultural pesticides and related potential exposure risks to water quality in China

Estimation and evaluation of usage, loss and ecological risk of neonicotinoid pesticides in a large catchment

Neonicotinoid pesticides (NNs) are increasingly used in agriculture, which may pose significant threats to aquatic organisms in receiving rivers. However, no studies have explored their entire process from application and transport to receptors within river basins. Here, we estimated the usage and loss of NNs in the Dongting Lake Basin in China using modeling approaches, and assessed NNs-associated aquatic ecological risks. Our research data showed that the annual usage of the nine NNs reached 1895 tonnes in the basin, with the peri-urban areas being the major users. We further calibrated and validated a SWAT model using various 13-years hydrological data and field measured NNs concentration data. The simulated total annual loss of NNs was 121 tonnes in the entire basin, 94 tonnes of which were discharged into the Dongting Lake. An obvious monthly variation was observed in the lake basin, with relatively higher NNs concentrations being found in summer. Results from the ecological risk assessment showed that NNs posed significant risks to aquatic organisms in approximately 11.2 % of river sections in the whole basin. The present study underscores the significant issue of NNs loss in the Dongting Lake Basin and warrants great attention to their potential risks to aquatic organisms.

Environmental fates of thiophosphate and triazole fungicides in a paddy-dominated basin

Under the widespread use backgrounds of fungicides in paddy-dominated basin, the neglect of fungicide environmental fates may aggravate their pollution risks. By integrating field detection with model simulation, we quantified the loss loads and explored the environmental fates of one thiophosphate and five triazole fungicides. Based on the experimental results, we simulated fungicide loss loads with the coefficient of determination of the verification results greater than 0.5 (with p-value less than 0.01). The model simulation results revealed that the extensive distribution of paddy fields and the rough terrain in the lower reaches attributed to higher loss loads observed downstream than upstream. Meanwhile, the loss loads in study watershed concentrated from May to October, constituting 92.69 % of the annual total. A robust correlation between fungicide loss and precipitation (with the coefficient of determination greater than or equal to 0.51, p-value less than 0.01) underscores the pivotal role of rainfall in mediating fungicide migration. Transportation has emerged as the primary environmental behavior of fungicides, accounting for at least 92.87 % of the total flux. Furthermore, the results of field investigation showed the application pattern of fungicides also affected the spatial and temporal characteristics of fungicide loss and also the loss load. The combination of experiment and model revealed the migration and distribution patterns of fungicides in the paddy-dominated watershed, facilitating effective management at catchment scale.

Pesticide exposure and forage shortage in rice cropping system prevents honey bee colony establishment

As one of the key stable crops to feed half of the world's population, how rice cropping system affects honey bee health regarding pesticide exposure and forage availability is under investigated. We predicted honey bees were stressed by high pesticide exposure and forage dearth in monoculture rice systems. Providing access to natural habitats is a typical approach to mitigate the negative impact of intensive agriculture on honey bees. We aimed to determine if bee colonies located in landscapes with more cover of forest habitat would collect more forage and be exposed to less pesticides. We selected beekeeping locations in rice dominated landscapes (as control), mosaic landscapes of rice and medium woodland (MW) cover, and landscapes of high woodland (HW) cover, respectively, in July when rice starts bloom and pesticides are commonly used. Colonies were inspected at a biweekly frequency from July to October with population growth and forage (nectar and pollen) availability estimated. Pollen and bees were collected in middle August for pesticide exposure analysis. We did not observe enhancement in forage availability and reduction in pesticide exposure in landscapes with increased forest habitat (i.e., MW or HW cover), and all colonies failed in the end. Other natural habitats that can supplement flower shortage periods in forest can be considered for supporting bee health. Our results suggest that forest should be carefully assessed for being incorporated into beekeeping management or pollinator conservation when forest phenology can be a factor to affect its impact as a natural habitat.

The dual impacts of specialized agricultural services on pesticide application intensity: Evidence from China

BACKGROUND

Specialized agricultural services are a new trend in agricultural production around the world, especially in developing countries. However, the growing impacts of specialized agricultural services on pesticide application intensity are unclear. In regions facing pesticide overuse, do specialized agricultural services exacerbate or mitigate the problem?

RESULTS

Based on province-level panel data from China from 2004 to 2018, this study examines the impact of specialized agricultural services on pesticide application intensity, considering both direct and indirect (i.e. spatial spillover) effects. The dual impacts of specialized agricultural services on pesticide application intensity in China are identified. First, specialized agricultural services directly increase pesticide application intensity, likely due to increased cultivation and specialized management of land that was previously abandoned or marginally managed. Second, there is a negative indirect or spatial spillover effect of specialized agricultural services on pesticide application intensity, likely due to technology and efficiency diffusion enabled by the cross-regional provision of specialized agricultural services. The net impact of specialized agricultural services on pesticide application intensity is negative.

CONCLUSION

Crop protection services are regarded as the core force to promote the reduction of pesticide application intensity. Steps should be taken to promote the research and development, demonstration, and promotion of new technologies and equipment for crop protection services, particularly the development of crop protection by drones. © 2022 Society of Chemical Industry.

Pesticide fate at watershed scale: A new framework integrating multimedia behavior with hydrological processes

Pesticide pollution has been one serious ecological and environmental issue due to its wide application, high toxicity, and complex environmental behavior. The fugacity model has been widely used to quantify biogeochemical cycles of pesticides due to its clear compartments, simple structure, and easy-accessible data. However, the lack of detailed hydrological processes limits its application for large and heterogeneous watershed. In present study, a new framework was proposed through integration of hydrological processes of SWAT and pesticide fate of fugacity model, and was applied into a typical watershed in the Three Gorges Reservoir Area, China. The results showed that surface runoff, soil erosion, and percolation varied spatiotemporally, which highlighted the importance of considering regional and seasonal heterogeneity of pesticide transport variables in the fugacity model. The amount of dichlorvos (DDV) and chlorpyrifos (CHP) in air, water, soil, and sediment phase were estimated as 0.26 kg, 19.77 kg, 1.06 × 10⁴ kg, and 0.55 kg, respectively. Spatiotemporally, pesticide concentrations in water phase peaked in summer, while the middle and southwest regions of the watershed were identified as the hotspots for pesticide pollution. Compared with the classical model, the new framework provided technical support for the pesticide assessment at watershed scale with heterogeneous hydrological conditions, which can be easily extended to other watersheds, and integrated with other models for comprehensive agricultural management.

Past and future pesticide losses to Chinese waters under socioeconomic development and climate change

Increasing pesticide use pollutes Chinese surface waters. Pesticides often enter waters through surface runoff from agricultural fields. This occurs especially during heavy rainfall events. Socio-economic development and climate change may accelerate future loss of pesticides to surface waters due to increasing food production and rainfall events. The main objective of this study is to model past and future pesticide losses to Chinese waters under socio-economic development and climate change. To this end, we developed a pesticide model with local information to quantify the potential pesticide runoff from near-stream agriculture to surface waters after heavy rainfall. We project future trends in potential pesticide runoff. For this, we developed three scenarios: Sustainability, "Middle of the Road" and Economy-first. These scenarios are based on combined Shared Socio-economic Pathways and Representative Concentration Pathways. We identified hotspots with high potential pesticide runoff. The results show that the potential pesticide runoff increased by 45% from 2000 to 2010, nationally. Over 50% of the national pesticide runoff in 2000 was in five provinces. Over 60% of the Chinese population lived in pesticide polluted hotspots in 2000. For the future, trends differ among scenarios and years. The largest increase is projected for the Economy-first scenario, where the potential pesticide runoff is projected to increase by 85% between 2010 and 2099. Future pesticide pollution hotspots are projected to concentrate in the south and south-east of China. This is the net-effect of high pesticide application, intensive crop production and high precipitation due to climate change. In our scenarios, 58%-84% of the population is projected to live in pesticide polluted hotspots from 2050 onwards. These projections can support the development of regional management strategies to control pesticide pollution in waters in the future.

Assessing the sustainability of ecosystems over fourteen years of cultivation in Longnan City of China based on emergy analysis method

Currently, the contradiction between the limited resources of China's cultivated ecosystems and population growth is becoming increasingly evident, and the negative impacts on the environment and human activities need to be curbed. Therefore, it is crucial to quantify the sustainability of cultivated ecosystems and determine these driving factors that affect their development. This study used the emergy method to quantify the input/output flow and sustainable development of the cultivated land ecosystem in Longnan City, combined with the logarithmic mean divisia index decomposition analysis (LMDI) method to evaluate the driving factors of sustainable development in the region. The results demonstrate that from 2004 to 2017, the total emergy input and output of Longnan City showed an upward trend, and non-renewable resources (N) were always in a dominant state in the total emergy (T) input, and their proportion rose from 59.69% to 66.92%. The emergy sustainability index (ESI) is less than 1, and the environmental pressure of the system is relatively higher. Comprehensive emergy production ratio (EPR), emergy investment ratio (EIR), the renewable fraction (R%), emergy yield ratio (EYR) and environmental load ratio (ELR), showed that the agricultural ecological economy in Longnan still has great development potential, and clean energy should be developed as far as possible to replace fossil fuels in future planning. LMDI results showed that the intensity factor ΔY^'A is the main driving factor for the positive development of ESI. The government's ecological protection requirements can reduce waste emissions through reasonable farming system and advocating the use of organic fertilizer, so as to achieve the purpose of improving crop yield. Vigorous development of green ecological agricultural production patterns can improve the sustainability of arable ecosystems. This study can provide a theoretical basis for the sustainable development of cultivated ecosystems and the formulation of related agricultural production measures.

Identification method and application of critical load contribution areas based on river retention effect

For the entire watershed, the critical source areas (CSAs) and the critical load contribution areas (CLCAs) are two completely different concepts. The CLCAs can reflect the impact of river retention effects on pollutant transmission. In this study, an integrated modelling approach was developed for those complex watersheds by combining two models: MECM (modified export coefficient model) and SWAT (Soil and Water Assessment Tool). A case study was performed in a typical rural area-Miyun Reservoir watershed, China. The simulated results indicated that anthropogenic pollution is the main source of pollutants in most townships, including livestock breeding, rural activities, and crop cultivation. It spreads upstream with the outlet of the basin as the center, and the transport efficiency decays regularly, so the location of the pollution source is closely related to its transport efficiency. The river retention effect has a significant retardation effect on the transportation of pollutants, more than half of the pollutant load will be deposited in the river network. Generally, the CLCAs are concentrated in the area where the transport efficiency and pollutant load are relatively high, which is quite different from the spatial distribution of the CSAs. The research results fully excavated the transmission path and process of pollutants, especially the process of river migration, which helps to improve the scientific configuration of management practices.

Retrieval of Total Phosphorus Concentration in the Surface Water of Miyun Reservoir Based on Remote Sensing Data and Machine Learning Algorithms

Some essential water conservation areas in China have continuously suffered from various serious problems such as water pollution and water quality deterioration in recent decades and thus called for real-time water pollution monitoring system underwater resources management. On the basis of the remote sensing data and ground monitoring data, this study firstly constructed a more accurate retrieval model for total phosphorus (TP) concentration by comparing 12 machine learning algorithms, including support vector machine (SVM), artificial neural network (ANN), Bayesian ridge regression (BRR), lasso regression (Lasso), elastic net (EN), linear regression (LR), decision tree regressor (DTR), K neighbor regressor (KNR), random forest regressor (RFR), extra trees regressor (ETR), AdaBoost regressor (ABR) and gradient boosting regressor (GBR). Then, this study applied the constructed retrieval model to explore the spatial-temporal evolution of the Miyun Reservoir and finally assessed the water quality. The results showed that the model of TP concentration built by the ETR algorithm had the best accuracy, with the coefficient R2 reaching over 85% and the mean absolute error lower than 0.000433. The TP concentration in Miyun Reservoir was between 0.0380 and 0.1298 mg/L, and there was relatively significant spatial and temporal heterogeneity. It changed remarkably during the periods of the flood season, winter tillage, planting, and regreening, and it was lower in summer than in other seasons. Moreover, the TP in the southwest part of the reservoir was generally lower than in the northeast, as there was less human activities interference. According to the Environmental Quality Standard for the surface water environment, the water quality of Miyun Reservoir was overall safe, except only for an over-standard case occurrence in the spring and September. These conclusions can provide a significant scientific reference for water quality monitoring and management in Miyun Reservoir.

Screening of potential oestrogen receptor α agonists in pesticides via in silico, in vitro and in vivo methods

In modern agricultural management, the use of pesticides is indispensable. Due to their massive use worldwide, pesticides represent a latent risk to both humans and the environment. In the present study, 1056 frequently used pesticides were screened for oestrogen receptor (ER) agonistic activity by using in silico methods. We found that 72 and 47 pesticides potentially have ER agonistic activity by the machine learning methods random forest (RF) and deep neural network (DNN), respectively. Among endocrine-disrupting chemicals (EDCs), 14 have been reported as EDCs or ER agonists by previous studies. We selected 3 reported and 7 previously unreported pesticides from 76 potential ER agonists to further assess ERα agonistic activity. All 10 selected pesticides exhibited ERα agonistic activity in human cells or zebrafish. In the dual-luciferase reporter gene assays, six pesticides exhibited ERα agonistic activity. Additionally, nine pesticides could induce mRNA expression of the pS2 and NRF1 genes in MCF-7 cells, and seven pesticides could induce mRNA expression of the vtg1 and vtg2 genes in zebrafish. Importantly, the remaining 48 out of 76 potential ER agonists, none of which have previously been reported to have endocrine-disrupting effects or oestrogenic activity, should be of great concern. Our screening results can inform environmental protection goals and play an important role in environmental protection and early warnings to human health.

Pesticides and herbicides

This paper highlights a review of scientific papers published in the year 2019 regarding pesticides and herbicides. The scientific review presented in this paper includes the presence and occurrence of pesticides and herbicides in the environment. The entire review divided into different sections, which are grouped into four main sections. Each of these sections provides studies conducted on toxicology, ecological risk assessment, strategies of treatment, policies, modeling, and guidelines regarding pesticides and herbicides management. PRACTITIONERS POINTS: This paper highlights the review of scientific literature published in the year 2019. The review includes the presence and occurrence of pesticides and herbicides in the environment. The review focuses on toxicology, ecological risk assessment, strategies of treatment, policies, modelling and guidelines regarding pesticides and herbicides management. The literature review covers selected papers relevant to the topic.

Removal of methylene blue from aqueous solutions by biochar prepared from the pyrolysis of mixed municipal discarded material

This paper investigates the adsorption of organic compounds in aqueous solution to biochar adsorbent, using methylene blue as an indicator for adsorption. Biochar was produced by the pyrolysis of mixed municipal discarded material in an innovative heat pipe reactor, the pyrolysis temperature was held at 300°C for 12 h. Biochar produced under these conditions was found to have oxygen containing functional groups that are beneficial to the adsorption of methylene blue as well as graphitic structures suggesting potential sites for π-π interactions with methylene blue. Methylene Blue followed the pseudo second order kinetic model with higher R² values than both the pseudo first order kinetic and intraparticle diffusion models. The adsorption also closely fit the Langmuir isotherm rather than the Freundlich model, suggesting monolayer adsorption rather than multilayer adsorption. Maximum adsorption capacity was observed at 7.2 mg/g for initial concentration of 100 mg/l Methylene blue in aqueous solution. The amount of Methylene blue adsorbed increased with increasing initial concentration as expected. The adsorption mechanisms are likely π-π interactions between methylene blue and the graphitic structures in the biochar which are shown to be present in Raman spectroscopy, as well as electrostatic attraction and ionic bonding between negatively charged surface sites on the char and the positive charge on the dissolved methylene blue molecules. The results show that biochar obtained from mixed waste could be employed as a low-cost and effective tool in water treatment for the removal of basic dyes and potentially other organic impurities.

Evaluating national ecological risk of agricultural pesticides from 2004 to 2017 in China

In recent years, excessive application and loss of pesticides have caused great risks to the aquatic systems, but the spatio-temporal variability in the ecological risk that agricultural pesticides pose to aquatic systems has not been explored at the national scale. In this study, an integrated assessment framework was proposed for the potential ecological risk of surface water caused by agricultural pesticide loss. The spatio-temporal variability in the potential ecological risk caused by agricultural pesticide runoff was evaluated. Based on the results, the total pesticide emissions increased from 165.47 tons in 2004 to 179.77 tons in 2017. Among the three pesticide types, insecticide had the largest application, but its runoff was estimated as the lowest. High-risk areas of insecticide runoff were concentrated in the east, south and central part of China, while the central region of China was identified as a hotspot due to the high and the ever-increasing ecological risk. This study provides an integrated method for potential ecological risk assessment of agricultural pesticide runoff to adjacent water bodies in large-scale regions and the results of the study have direct implications for environmental policies on pesticide management in China and around the world.

Identification of Critical Source Areas of Nitrogen Load in the Miyun Reservoir Watershed under Different Hydrological Conditions

The spatiotemporal distribution of critical source areas (CSAs) will change with hydrological conditions. In this study, the CSAs of nitrogen load under different hydrological conditions in the Chaohe River watershed were identified using the cumulative pollution load curve method determined from the nitrogen pollution simulated using the Soil and Water Assessment Tool (SWAT) model. The results showed that: (1) The order of factors impacting nitrogen load intensity is as follows: fertilization intensity, rainfall, runoff, land use type, slope type, and soil type. (2) The primary and secondary CSAs are concentrated in the upper and lower areas of the watershed, where cultivated land (8.36%) and grassland (52.55%) are more abundant. The potential pollution source areas are concentrated in the upper and middle areas of the watershed, where cultivated land (6.99%), grassland (42.37%), and forest land (48.18%) are evenly distributed. The low-risk source areas are concentrated in the middle and left bank of the watershed, where forest land (67.65%) is dominant and the vegetation coverage is highest. The research results have significance for improving the accuracy of the implementation of best management practices, and can provide a reference for the formulation of drinking water protection policies for Beijing.

Pharmaceuticals, pesticides, personal care products and microplastics contamination assessment of Al-Hassa irrigation network (Saudi Arabia) and its shallow lakes

This study assess the presence of pharmaceutical and personal care products (PPCPs) and pesticides in different environmental compartments and microplastics in water of a characteristic lagoon wetland in Saudi Arabia to establish the transport, accumulation and fate of these pollutants in a water-stressed area under high anthropogenic pressure. In water, diazinon (up to 1016 ng L^-1), caffeine (up to 20,663 ng L^-1), diclofenac (up to 1390 ng L^-1) and paracetamol (up to 3069 ng L^-1) were at the highest concentrations. The substances with the highest frequency of detection were carbendazim, atorvastatin, caffeine, etoricoxib, lorazepam, metformin, ofloxacin, paracetamol, salicylic acid and tramadol. Considerably less pesticides and PPCPs at concentrations ranging from 0.01 to 126 ng g^-1 dry weight (d.w.) were detected in the other matrices (sediment ≫ soil > plants). The concentration of microplastics in water ranged from 0.7 to 7.8 items/L in the Al-Asfar lake and from 1.1 to 9.0 items/L in the Al-Hubail lake. Risk assessment [using hazards quotients (HQ)] was used to highlight pesticides and PPCPs of major ecological concern that should be closely monitored to avoid adverse effects.