Search Results (112)

The Soil and Water Assessment Tool (SWAT) was utilized to analyze the spatiotemporal distribution patterns of composite non-point source pollution in the Yapu Port Basin, China, and to quantify the pollutant load contributions from various sources. Scenario-based simulations were designed to assess the effectiveness of different mitigation strategies, focusing on both agricultural and urban non-point source pollution control. The watershed was divided into 39 sub-watersheds and 106 hydrologic response units (HRUs). Model calibration and validation were conducted using the observed data on runoff, total phosphorus (TP), and total nitrogen (TN). The results demonstrate good model performance, with coefficients of determination (R²) ≥ 0.85 and Nash–Sutcliffe efficiencies (NSEs) ≥ 0.84, indicating its applicability to the study area. Temporally, pollutant loads exhibited a positive correlation with precipitation, with peak values observed during the annual flood season. Spatially, pollution intensity increased from upstream to downstream, with the western region of the watershed showing higher loss intensity. Pollution was predominantly concentrated in the downstream region. Based on the composite source analysis, a series of management measures were designed targeting both agricultural and urban non-point source pollution. Among individual measures, fertilizer reduction in agricultural fields and the establishment of vegetative buffer strips demonstrated the highest effectiveness. Combined management strategies significantly enhanced pollution control, with average TN and TP load reductions of 22.18% and 22.70%, respectively. The most effective scenario combined fertilizer reduction, improved urban stormwater utilization, vegetative buffer strips, and grassed swales in both farmland and orchards, resulting in TN and TP reductions of 67.2% and 56.2%, respectively. Full article

Non-point source (NPS) pollution from agriculture accounts for more than 20% of the total pollution load in the Republic of Korea, with the highest nutrient balance among OECD countries. Rice paddy fields are among the most important NPSs because of their large area, intensive fertilizer use, intensive use of irrigation water, and subsequent drainage. Therefore, the use of controlled drainage in paddy fields (Test) was evaluated for reduction in the discharged volumes and pollutant loads in drainage and stormwater runoff in comparison to plots using traditional drainages (Control). The results show that the loads were highly variable and that the reductions in the annual load of biochemical oxygen demand (BOD), suspended solid (SS), total nitrogen (T-N), total phosphorus (T-P), and total organic carbon (TOC) in the Test compared to that of the Control were 31.0 ± 28.9%, 83.5 ± 11.8%, 65.4 ± 12.2%, 69.1 ± 21.7%, and 64.9 ± 12.9%, respectively. It was shown that discharge in the post-harrowing and transplanting drainage (HD) was predominantly responsible for the total loads; therefore, the load reduction in HD was evaluated further at additional sites. The reduction at all studied sites was highly variable and as follows: 30.0 ± 33.6%, 70.9 ± 24.6%, 32.2 ± 45.5%, 45.7 ± 37.0%, and 27.0 ± 71.5%, for BOD, SS, T-N, T-P, and TOC, respectively. It was also demonstrated that controlled drainage contributed significantly to reducing the loads and volume of stormwater runoff from paddy fields. Correlations between paddy field conditions and multiple regression showed that the loads were significantly related to paddy water quality. The results of this study strongly suggest that controlled drainage is an excellent alternative for reducing the discharge of NPS pollutants from paddy fields. It is also suggested that the best discharge control would be achieved by combinations of various discharge mitigation alternatives, such as the management of irrigation, drainage, and fertilization, as well as drainage treatment, supported by more field tests, identification of the fates of pollutants, effects of rainfall, and climate changes. Full article

Water security is a basic requirement of a region’s residents and also an important point of discussion worldwide. The middle route of the south-to-north water diversion project (MR-SNWDP) represents the most extensive inter-basin water allocation scheme globally. It is the major water resource for the Beijing–Tianjin–Hebei region, and its security is of great significance. In this study, 28 indicators including society, nature, and economy were selected from the water sources of the MR-SNWDP from 2000 to 2017. According to the Drivers-Pressures-States-Impact-Response (DPSIR) framework principle, the entropy weight method was used for weight calculation, and the comprehensive evaluation method was used for evaluating the water security of the water sources of the MR-SNWDP. This study showed that the total loss of nonpoint source pollution (NPSP) in the water source showed a trend of slow growth, except in 2007. Over the past 18 years, the proportion of pollution from three NPSP sources, livestock, and poultry (LP) breeding industry, planting industry, and living sources, were 44.56%, 40.33%, and 15.11%, respectively. The main driving force of water security in all the areas of the water source was the total net income per capita of farmers. The main pressure was the amount of LP breeding and the amount of fertilizer application. The largest impact indicators were NPSP gray water footprint and soil erosion area, and water conservancy investment was the most effective response measure. Overall, the state of the water source safety was relatively stable, showing an overall upward trend, and it had remained at Grade III except for in 2005, 2006, and 2011. The state of water safety in all areas except Shiyan City was relatively stable, where the state of water safety had fluctuated greatly. Based on the assessment findings, implications for policy and decision-making suggestions for sustainable management of the water sources of the MR-SNWDP resources are put forward. Agricultural cultivation in water source areas should reduce the application of chemical fertilizers and accelerate the promotion of agricultural intensification. Water source areas should minimize retail livestock and poultry farming and promote ecological agriculture. The government should increase investment in water conservancy and return farmland to forests and grasslands, and at the same time strengthen the education of farmers’ awareness of environmental protection. The evaluation system of this study combined indicators such as the impact of agricultural nonpoint source pollution on water bodies, which is innovative and provides a reference for the water safety evaluation system. Full article

Agricultural activities such as fertilization and cultivation constitute a substantial source of non-point source (NPS) nitrogen (N) in aquatic ecosystems. Precise quantification of fluxes across diverse land uses and identification of critical source areas are essential for effectively mitigating nitrogen loads. In this study, the Soil Water Assessment Tool (SWAT) was employed to accurately model the watershed hydrology and total nitrogen (TN) transport in the Zhongtian River Basin, i.e., an agricultural watershed characterized by low mountainous terrain. The simulation results indicated that the average TN load intensity within the watershed was 21.34 kg ha⁻¹ yr⁻¹, and that TN load intensities for paddy fields and tea plantation were 34.96 and 33.04 kg ha⁻¹ yr⁻¹, respectively. Agricultural land, which covered 32.06% of the area, disproportionately contributed 52.88% of the N output in the watershed. Pearson and redundancy analysis (RDA) underscored land use as the primary driver of nitrogen emissions, with a contribution exceeding 50%. Building on a high-precision simulation analysis, a suite of best management practices (BMPs) was established. These findings highlight the superior performance of engineered BMPs over agricultural BMPs, with TN load reduction rates of 12.23 and 27.07% for filter strips and grassed waterways, respectively. Among three agricultural BMPs, the effect of fertilizer reduction was the most pronounced, achieving reductions of 6.44% for TN and 21.26% for nitrate. These results suggest that optimizing fertilizer management and implementing engineered BMPs could significantly reduce nitrogen pollution in agricultural watersheds, providing valuable insights for sustainable agricultural practices and water quality management. Full article

Agricultural non-point source pollution (ANPSP) significantly affects worldwide water quality, soil integrity, and ecosystems. Primary factors are nutrient runoff, pesticide leaching, and inadequate livestock waste management. Nonetheless, a thorough assessment of ANPSP sources and efficient control techniques is still lacking. This research delineates the origins and present state of ANPSP, emphasizing its influence on agricultural practices, livestock, and rural waste management. It assesses current evaluation models, encompassing field- and watershed-scale methodologies, and investigates novel technologies such as Artificial Intelligence (AI), Machine Learning (ML), and the Internet of Things (IoT) that possess the potential to enhance pollution monitoring and predictive precision. The research examines strategies designed to alleviate ANPSP, such as sustainable agricultural practices, fertilizer reduction, and waste management technology, highlighting the necessity for integrated, real-time monitoring systems. This report presents a comprehensive analysis of current tactics, finds significant gaps, and offers recommendations for enhancing both research and policy initiatives to tackle ANPSP and foster sustainable farming practices. Full article

This study investigated the relative contributions of natural and anthropogenic factors to the nutrient status of 33 representative lakes and reservoirs in the Yangtze River Basin. Using national water quality monitoring data, remote sensing imagery, Geographic Information System, (GIS), Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, and Redundancy Analysis (RDA), we analyzed the Spatiotemporal differences of total nitrogen (TN), total phosphorus (TP), the ratio of TN to TP (TN/TP), trophic level index (TLI), and habitat quality (HQ). Results revealed significant spatial heterogeneity in lake nutrient status, with upstream reservoirs exhibiting better water quality than their midstream and downstream counterparts. Over time, there is a decreasing trend in nutrient loads in lakes and reservoirs, yet the risk of eutrophication remains high. The middle and lower reaches of lakes and reservoirs face more severe eutrophication pressure. The contribution rates of natural factors and human activities to TN and TP in lakes and reservoirs are 19.1% and 35.0%, respectively. The main driving factors are livestock and poultry breeding volume, habitat quality, and urbanization, with contribution rates of 13.0%, 9.8%, and 0.2%, respectively. The contribution rates of natural factors and human activities to TN/TP and TLI of lakes and reservoirs are 19.8% and 15.5%, respectively. Actual Evapotranspiration (7.8%), habitat quality (7.3%), and hydraulic retention time (3.1%) were key drivers for the shifts of TN/TP and TLI. Management strategies should therefore control agricultural nitrogen fertilizer inputs upstream, industrial and agricultural non-point source pollution in the midstream, and enhanced wastewater treatment alongside population density and economic development control in the downstream areas. This research provides a crucial scientific basis for the ecological environment protection and sustainable utilization of water resources in the Yangtze River Basin. Full article

Total nitrogen (TN) and total phosphorus (TP) are essential indicators for assessing water quality. This study systematically analyzes the spatial and temporal distribution of TN and TP in China’s surface waters and examines the influence of natural factors and human activities on their concentrations. Utilizing data from 1387 monitoring sites (2020–2021) and employing K-means clustering and geographically weighted regression (GWR), we found that the national average concentrations were 3.89 mg/L for TN and 0.096 mg/L for TP. Spatially, higher TN and TP levels were observed in northern regions, coastal areas, and plains compared with southern, inland, and mountainous areas. Notably, TN concentrations reached up to 29.49 mg/L in the Haihe River basin and related plains, while TP peaked at 0.497 mg/L in the southeastern Shandong and northern Jiangsu coastal zones. Temporally, TN levels were approximately 50% higher in winter than summer, whereas TP levels were about 40% higher in summer. Key influencing factors included rainfall, elevation, fertilizer use, and population density, with spatial heterogeneity observed. Rainfall was the primary factor for TN change and the secondary factor for TP change. Soil type positively correlates with TN and TP changes, affecting non-point source pollution. Human activities such as land use, fertilizer application and population density had a significant effect on the nitrogen and phosphorus concentrations, while woodland had a significant impact on the improvement of water quality. The geographically weighted regression analysis showed spatial heterogeneity in the effects of each factor on TN and TP concentrations, and the best fit was at the watershed scale. The findings highlight the need for enhanced control of agricultural runoff, improved sewage treatment, and region-specific management strategies to inform effective water environment policies in China. Full article

Non-point source pollution from agricultural land use is a significant contributor to environmental pollution, causing serious threats to water, air, and soil quality. Environmental regulations have been shown to have a significant negative effect on pollutant emissions. However, empirical studies examining the impact of agricultural environmental regulations on cultivated land non-point source pollution are limited. To explore the effects of environmental regulations on cultivated land non-point source pollution, this study focuses on the Dongting Lake Plain. Using statistical data from 2010 to 2020, we analyze the temporal and spatial changes in cultivated land non-point source pollution before and after the implementation of the “Zero Growth of Fertilizer and Pesticide Use Action Plan”. A spatial econometric model is used to assess the impact of environmental regulations on pollution. The results indicate that non-point source pollution in the Dongting Lake Plain shows positive global spatial autocorrelation. Locally, in 2010 and 2015, high-high clusters were dominant, while low-low clusters were less common. By 2020, low-low clusters became the main pattern of pollution. The introduction of the Zero Growth Action Plan had a negative impact on pollution intensity within the region and positive spillover effects on neighboring areas. In terms of emission structure, the plan significantly reduced nitrogen emission intensity and pesticide loss, but had a positive impact on phosphorus emissions. The level of regional economic development had a significant negative effect on pollution intensity, while urbanization had a positive effect. Agricultural technological progress showed a negative spatial spillover effect on phosphorus emissions, and regional economic development had a negative spatial spillover effect on nitrogen and pesticide emissions. This study provides evidence of the impact of environmental regulations on cultivated land non-point source pollution and offers valuable insights for the development of future pollution control policies. Full article

The alterations in runoff resulting from changes in land use and land cover (LULC) were the primary influencing factors contributing to non-point source pollution (NPS). In order to evaluate the long-term hydrological consequences of LULC for the purposes of land use optimization in the Hulan River Basin, Northeast China, the validated Long-term Hydrological Impact Assessment (L-THIA) model was employed to simulate the spatiotemporal distribution of total nitrogen (TN) and total phosphorus (TP) non-point source (NPS) loads from 2000 to 2020. Additionally, the load per unit area index (LPUAI) method was utilized to identify critical source areas. The findings indicated that the regions with elevated pollution levels were predominantly situated in areas designated for agricultural and construction activities. The greatest contributor to nitrogen and phosphorus loads was agricultural land. There were clear increases in both TN and TP during the study period, with increases of 51.73% and 55.56%, respectively. As a consequence of the process of urbanization in the basin, the area of land devoted to construction activities increased, reaching a coverage of 5.02%. Nevertheless, the contribution of construction land to the total basin NPS load exceeded 10% in 2020. This was the primary factor contributing to the observed increase in pollution loads despite a reduction in agricultural land area over the past two decades. TN and TP loads were markedly higher during the flood season than the non-flood season, accounting for over 80% of the NPS load. The sub-watersheds in the southwest and northeast have been identified as significant sources of nitrogen and phosphorus loss, contributing to the overall burden of NPS pollution. Implementing measures such as fertilizer reduction and conversion of farmlands to forests and grasslands can effectively mitigate NPS pollution, particularly TN pollution. This study proposes that the integration of L-THIA with GIS can serve as a valuable tool for local planners to consider potential pollution risks during future planning and development activities. Full article

Nitrogen loss in water from farmland has become an environmental issue. Nitrogen fertilizer is the main cause of agricultural non-point source pollution in the Lake Basin, Yunnan. However, it is unclear how different nitrogen fertilizer forms affect water loss from farmland and how the root systems of crops respond. We established five nitrogen fertilizer treatments (100–0% [T1], 75–25% [T2], 50–50% [T3], 25–75% [T4], and 0–100% [(T5)] nitrate–ammonium) and performed an investigation to determine nitrogen loss in water and root morphological parameters of tobacco in Mile County and Chengjiang County. Compared with in the T1, T4, and T5 treatments, the total nitrogen loss in surface runoff was reduced by 4.67%, 11.85% and 9.56% in the T2 treatment and 27.32%, 23.20%, and 31.43% in the T3 treatment, respectively. Similar results were observed for the nitrogen loss due to infiltration. The root biomass was negatively correlated with nitrogen loss. There was greater root biomass, root surface area, and root spatial distribution in T2 and T3 compared with in T1, T4, and T5. These results indicate that 50–50% nitrate–ammonium nitrogen fertilizer can facilitate the root growth of tobacco and reduce nitrogen loss, which provides a reference for agricultural sustainable development. Full article

Non-point source (NPS) pollution has a complex formation mechanism, and identifying its primary controlling factors is crucial for effective pollution treatment. In this study, the Baixi Reservoir Watershed, characterized by low-intensity development, was selected as the study area. A new methodology combining the Soil and Water Assessment Tool (SWAT) with the Random Forest (RF) algorithm was proposed to comprehensively identify the primary controlling factors of NPS pollution and analyze the interaction between factors. The results of the validated SWAT model showed that the annual intensity of total nitrogen (TN) load range was 0.677–11.014 kg ha⁻¹ yr⁻¹, and the total phosphorus (TP) load per unit area range was 0.020–0.110 kg ha⁻¹ yr⁻¹. Loads of sediment, TP, and TN exhibited significant seasonal variations, particularly in the Baixi basin, where sediment yield had the highest absolute change rate, with a value of up to 232.26. Random Forest models for TN and TP displayed high accuracy (R² > 0.99) and robust generalization ability. Fertilization, sediment yield, and terrain slope were identified through RF models as the primary factors affecting TN and TP. By graphing partial dependency plots (PDPs) based on the results of the RF models to analyze the interaction between factors, the findings suggest a strong synergistic effect of two combined factors: fertilization and sediment yield. When fertilizer application exceeds 15 kg ha⁻¹ yr⁻¹ and sediment yield exceeds 3 kg ha⁻¹ yr⁻¹, there is a sharp increase in nitrogen and phosphorus load. Through the identification and analysis of the primary controlling factors of NPS pollution, this study provides a solid scientific foundation for developing effective watershed management strategies. Full article

China’s agricultural sector faces significant challenges, including fragmented farming practices, limited farmer knowledge of sustainable production, and outdated pest control technologies. These issues result in improper fertilization, pesticide application, and disposal of agricultural inputs, contributing to agricultural non-point source pollution and hindering the transition to a green economy. Thus, promoting green production behavior among farmers is critical for achieving carbon peaking, carbon neutrality, and harmonious coexistence between humans and nature. However, the existing literature on this topic is still relatively scarce. This study aims to investigate the impact of farmers’ cognition on their green production behavior (GPB). Considering the role of policy, this study also examines the moderating effect of government regulation in this relationship. An analysis of 306 survey responses from tea farmers in Jingmai Mountain, Pu’er City, Yunnan Province, reveals that farmers’ cognition exerts a significant and positive impact on GPB. Social norms and personal norms serve as chain mediators in the relationship between farmers’ cognition and GPB. Moreover, government regulation moderates the influence of farmers’ cognition on social norms, further amplifying its impact on them. This study advances the theoretical understanding of farmers’ behavior and offers practical insights for fostering the sustainable development of the tea industry. Full article

This study examines the economic and environmental impacts of green production practices among farmers. It aims to contribute to sustainable agricultural development, mitigate agricultural non-point source (NPS) pollution, and align environmental protection with economic growth. This paper utilizes survey data from 1345 farm households in the main rice production areas of Jiangxi Province, China, using the example of reduced fertilizer application (RFA) among rice farmers. This study constructs a slack-based measure data envelopment analysis (DEA—SBM) model with undesirable outputs to measure environmental effects and applies an endogenous switching regression model (ESRM) to test the economic and environmental effects of farmers’ adoption of green production technologies. We found the following: (1) The RFA behavior of farmers has a significant positive impact on their net profit per hectare (NPH), helping farmers increase their income, with the increase ranging from 2.05% to 6.54%. (2) Farmers’ RFA behavior has a significant positive impact on agricultural green productivity (AGP), contributing to the improvement of the environment, ranging from 44.09% to 45.35%. (3) A heterogeneity analysis found inconsistencies in the income-enhancing and environmental-enhancing effects at different quantiles of NPH and AGP. Therefore, attention should be placed on improving the agricultural product quality supervision system under the market circulation mechanism, creating land scale conditions conducive to the promotion and application of fertilizer reduction technologies and promoting the implementation of externality internalization compensation systems. Full article

Excessive fertilizer application increases the risk of eutrophication and agricultural non-point source pollution (ANPS) in rivers near farmland. However, the processes and mechanisms of runoff and phosphorus losses, particularly in the interflow, under various fertilizer treatments and rainfall scenarios are not well understood. This study used orthogonal experimental methods to investigate the combined effects of fertilization schemes and rainfall intensity on multi-form phosphorus runoff losses and to establish statistical relationships and regression models between phosphorus losses and environmental factors in surface runoff and interflow. The results indicated that (1) the optimized fertilization scheme, compared with conventional fertilization, enhanced pak choi (Brassica rapa) growth while reducing phosphorus runoff losses. By reducing phosphorus fertilization by 35.7%, total phosphorus losses decreased by 29.3%, 34.2%, and 29.8% under light, moderate, and heavy rainfall, respectively. (2) Different fertilizer applications and rainfall intensities had varying effects on phosphorus losses through different pathways. Fertilizer application was the primary factor affecting phosphorus losses in surface runoff, while rainfall intensity mainly influenced phosphorus losses through interflow. (3) Surface runoff was the dominant pathway for phosphorus losses from farmland (>92.0%), with particulate phosphorus (>89.4%) being the predominant form. However, under high-intensity and long-duration rainfall, interflow became a significant pathway for phosphorus losses. This study highlights the importance of optimized fertilization in reducing phosphorus losses and improving fertilizer efficiency in agricultural fields. The findings will help develop strategies to mitigate ANPS and soil nutrient losses in the North China Plain. Full article

In order to address the increasingly prominent issues of water resource protection and agricultural non-point source pollution in the Erhai Lake Basin, this study conducted a two-year field experiment in Gusheng Village, located in the Erhai Lake Basin. In 2022, two irrigation treatments were set up: conventional flooding irrigation (CK) and controlled irrigation (C), with three replicates for each treatment. In 2023, aiming to enhance the utilization rate of rainwater resources and reduce the direct discharge of dry-farming tailwater from upstream into Erhai Lake. The paddy field was used as an ecological storage basin, and the water storage depth of the paddy field was increased compared to the depth of 2022. Combined with the deep storage of rainwater, the dry-farming tailwater was recharged into the paddy field to reduce the drainage. In 2023, two water treatments, flooding irrigation with deep storage and controlled drainage (CKCD) and water-saving irrigation with deep storage and controlled drainage (CCD) were set up, and each treatment was set up with three replicates. The growth and physiological index of rice at various stages were observed. Nitrogen leaching of paddy field in surface water, soil water, and groundwater under different water treatments after tillering fertilizer were observed. The research results show that the combined application of organic and inorganic fertilizers under organic planting can provide more reasonable nutrient supply for rice, promote dry matter accumulation and other indices, and also reduce the concentration of NH₄⁺-N in surface water. Compared with CK, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of C are increased by 4.8%, 4.1%, 20.9%, and 9.7%, respectively. Compared with CKCD, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of CCD are increased by 6.5%, 3.8%, 19.6%, and 21.9%, respectively. The yield in 2023 is 19% higher than that in 2022. Treatment C can increase the growth indicators and reduce the net photosynthetic rate to a certain extent, while CCD rain-flood storage can alleviate the inhibition of low irrigation lower limit on the net photosynthetic rate of rice. Both C and CCD can reduce nitrogen loss and irrigation amount in paddy fields. CCD can reduce the tailwater in the Gusheng area of the Erhai Lake Basin to Erhai Lake, and also can make full use of N, P, and other nutrients in the tailwater to promote the formation and development of rice. In conclusion, the paddy field rain-flood storage methodology in the Erhai Lake Basin can promote various growth and physiological indicators of rice, improve water resource utilization efficiency, reduce direct discharge of tailwater into Erhai Lake, and decrease the risk of agricultural non-point source pollution. Full article