Agricultural Non-point Source Pollution Control Research Articles

“Period-area-source” hierarchical management for agricultural non-point source pollution in typical watershed with integrated planting and breeding

Agricultural non-point source (NPS) pollution threatens the aquatic environments significantly. Insufficient attention to the migration characteristics of multiple sources of pollution as well as the variability of anthropogenic interference hinders effective pollution control, particularly in watersheds with integrated planting and breeding (IPB). In this study, we proposed a distributed dual-structure empirical export model for IPB (DSEEM-IPB) that optimizes hydrological processes in pollutant transport and refines NPS load estimation from animal breeding sources to simulate agricultural NPS pollution in a typical IPB watershed. Based on the estimated NPS load, a “period-area-source” management approach for NPS pollution is proposed with a co-analysis of critical periods (CPs), critical source areas (CSAs), and critical source types (CSTs). The results show that (1) the CPs of only two months (June and July) contributed 62.9% and 56.2% of the total nitrogen (TN) and total phosphorus (TP) load respectively; (2) the CSAs in the CPs contributed 17.6% of the TN load within 14.0% of the area and 16.2% of the TP load within 13.4% of the area; (3) planting (74.4%) is the primary source of nitrogen loss while breeding (58.3%) is the primary source of phosphorus loss; and (4) optimal control measures should target planting sources in CSAs and sub-CSAs within CPs (yielding 32.4% of annual TN loads) and breeding sources in CSAs within non-CPs (yielding 22.1% of annual TP loads). This study indicates that prioritizing pollution management of critical sources from critical areas or periods can achieve efficient and targeted control of agricultural NPS pollution.

Factors Influencing Willingness of Farmers to Pay for Agricultural Non-point Source Pollution Control Based on Distributed Cognitive Theory

The analysis of the willingness of individual farmers to cover costs is an important basis for measuring the economic value of agricultural non-point pollution management， and determining the ecological and economic value of rural surface pollution control is a necessary measure to internalize the externalities of agricultural production. Based on the analysis of the hierarchy of factors influencing the cognition of farmers， this study constructed a theoretical framework based on distributed cognition theory to analyze their willingness to pay for agricultural non-point source pollution control from the perspective of individual farmers. On the basis of this framework， we used the Double-Hurdle model to empirically test the overall process of farmers'willingness to pay and their willingness to pay the amount for agricultural non-point source pollution control by combining 531 microscopic research datapoints in Guanzhong， Shaanxi Province. The results showed that： ① the number of farmers with willingness to pay for agricultural non-point source pollution control was 267， accounting for 50.30% of the total sample， and the average value of willingness to pay was 1 469.77 yuan·hm-2； the total economic value of agricultural non-point source pollution control in Shaanxi Province in 2020 was estimated to be 5.791 billion yuan based on the expected value of the willingness to pay level of the research sample. ② Farmers'willingness to pay for agricultural non-point source pollution control was influenced by the combined effects of personal， regional， and cultural forces， and the effects of each dimension were similar； farmers' willingness to pay for agricultural non-point source pollution control was mainly influenced by the cultural force factor， and the effects of personal and regional forces were very limited. ③ The results of the regressions by income level showed that personal and cultural strengths had a significant impact on the willingness to pay among the low-income group but did not contribute to the increase in the willingness to pay.

Intensive agricultural management-induced subsurface accumulation of water-extractable colloidal P in a Vertisol

Abstract. Long-term excessive application of mineral fertilizer leads to phosphorus (P) accumulation, increasing the risk of P migration and loss from the soil profile. The colloids in the soil profile are important carriers for P migration due to their high P adsorption and transport capacity. It is not clearly understood how colloidal P (CP) is distributed in subsoils (<1.2 m) of a Vertisol, contributing to subsurface P loss. Understanding the depth sequence distribution and speciation of colloidal P in the soil profile is critical for a comprehensive assessment of P loss. In this study, water-extractable colloids (WECs) with the size of 0.35–2 µm were obtained from a 0–120 cm soil profile by a sedimentation and centrifugation scheme. The dissolved reactive P (DRP) and dissolved total P (DTP) in soil supernatant with particle sizes <0.35 µm were measured by molybdate blue colorimetry. Solution 31P nuclear magnetic resonance (NMR) and P K-edge XANES (X-ray absorption near-edge structure) were used to characterize the species and distribution of CP in the soil profile of fertilized farmland. Total and available P in bulk soil and colloids decreased with soil depth. The organic P (OP) contained 97–344 mg kg−1 per bulk soil and 110–630 mg kg−1 per WEC. The OP in soil profile consists of orthophosphate mono-esters and diesters primarily according to NMR results. It suggested that OP in WECs from subsoils might be affected by the translocation of CP from surface soils, probably due to soil acidification and preferential flow caused by swelling–shrinkage clays, including montmorillonite and nontronite detected by X-ray powder diffractometer (XRD) results. Additionally, the more negative zeta potential of surface soil colloids suggests the high mobility of colloidal P towards the subsoils. The CP concentration for <2 µm was about 38–93 mg P kg−1 per bulk soil, which is 6–37 times that of DRP, suggesting that CP plays a dominant role in P transport within the soil profile. The relatively small fraction of orthophosphate diesters suggests limited P assimilation by microorganisms for the accumulation of WECs containing organically bound P in subsoils. The P K-edge XANES results indicated that the proportions of Al-P, Fe-P, and inositol hexakisphosphate (IHP) of WECs decreased, but hydroxyapatite (HAP) increased with soil depth. This study showed that inorganic and organic P migrated from the surface to deeper layers along the soil profile, with soil colloids having a significant effect on P migration from both surface and subsurface layers. The findings have an important significance for soil P migration evaluation and agricultural non-point source pollution control in Vertisols.

Research on the Performance Evaluation of Agricultural Non-point Source Pollution Prevention and Control in Anhui Province

Agricultural and rural pollution control is a key and difficult issue in the revitalization of rural ecology in China, and agricultural non-point source pollution, as the main source of pollution, is of the utmost importance. Building a performance audit system for agricultural non-point source pollution prevention and control is beneficial for measuring the degree of agricultural non-point source pollution prevention and control, identifying constraints, and is of great significance for agricultural non-point source pollution prevention and control. This article selects Anhui Province as the research object, and based on the PSR model of environmental resource management, constructs an agricultural non-point source pollution performance evaluation system. On the basis of this evaluation system, the entropy weight TOPSIS method is used to empirically investigate the agricultural non-point source pollution prevention and control data in Anhui Province from 2017 to 2021, and corresponding suggestions are proposed based on the specific analysis results.

A spatiotemporal optimization method for nutrient control in lake watersheds

Developing an efficient strategy for managing nutrients in less-developed lake watersheds that can balance the need for socioeconomic progress with the protection of aquatic ecosystems has become an urgent research subject for achieving sustainable development. This paper improves the optimization method for environmental and economic management of lake watersheds proposed in our previous research. A spatiotemporal optimization method based on a coupling model consisting of the Soil and Water Assessment Tool, system dynamics model, and objective programming model was applied to an agricultural non-point source (ANPS) pollution control program and a rural sewage treatment program at the Yilong Lake watershed as a case study. A simulation evaluation showed that the efficiency of the previous scheme was significantly improved after conducting spatiotemporal optimization. This scheme was dynamic and distributed, demonstrating an annual and high-resolution control program that can provide a basis for the precise management of ANPS. Although it still requires improvement, a framework for coupling simulation and two-step optimization was achieved in this study.

An integrated framework for agricultural non-point source pollution control technology evaluation: Application of an improved multiple attribute decision making method

An Intuitionistic Fuzzy - Combined Weight - Mahalanobis distance - Multiple Attribute Decision Making (IFCM-MADM) method is proposed to solve comprehensive evaluation problem of the pollution control technologies for non-point sources in planting industry. The method is able to achieve cooperative improvement of the traditional TOPSIS on quantitative transformation of qualitative data in the evaluation indices by integrated intuitionistic fuzzy theory, subjective–objective combination weight calculation for the evaluation indicators by coupling the AHP and entropy weighting method, and accurately calculation on the distance between the evaluation object and the positive/negative solution by introducing the Mahalanobis distance to avoid the impact of correlation between indicators. Then, 34 typical technologies for agricultural non-point source pollution control selected from Major Science and Technology Program for Water Pollution Control and Treatment (MSTPWPCT) in China are employed for case application and validation, and the evaluation result obtained by IFCM- MADM has been deeply analyzed by comparing with the recommendation technologies provided by MSTPWPCT and the other two evaluation methods. The result shows that, the IFCM- MADM method can provide a scientific evaluation and selection of the technologies with high comprehensive benefits (including economic benefits, environmental benefits, and technical performance), which is highly consistent with the recommendation result from MSTPWPCT, and is capable to weaken the disadvantage of the objective weighting method and subjective weighting method, to a certain extent. The proposal of IFCM-MADM is the first attempt to enhance the traditional TOPSIS by extending its abilities on quantitative data processing, index weight calculation and accurate calculation of relative closeness, concurrently, and the method is also appropriate to other practical environmental evaluation problems with high complexity and multiple attributes.

Research on the Progress of Agricultural Non-Point Source Pollution Management in China: A Review

In the 1980s, China began to recognize the gravity of the problem of non-point agricultural source pollution and conduct research on it. Agricultural non-point source pollution in China, on the other hand, differs from foreign agricultural non-point source pollution and industrial point source pollution. Because the features of agricultural non-point source pollution are complicated, it is critical to investigate a whole-chain management policy system appropriate for China’s agricultural pattern. Based on the current situation of agricultural non-point source pollution in China, this study summarizes the four stages of agricultural non-point source pollution prevention and control policies, namely the discovery stage with macro policies as the main focus, the exploration stage with single research indicators, the initial systematic strengthening stage, and the focused stage with targeted characteristics. Simultaneously, it examined the technological approaches that are suitable for China’s national circumstances and have been investigated by relying on international experience in present-day Chinese management. However, there are still some problems and challenges in agricultural non-point source pollution management policies, such as a lack of non-point source information support, a lack of coordination between different departments, a lack of support in measurement and retroactive calculation and treatment, a lack of an in-depth concept of zoning and classification, a lack of policy, an institutional system, and insufficient capital investment. Based on these problems and combining them with Green Agriculture, Beautiful China, and other goals, this paper puts forward suggestions to strengthen the policy data support of the agricultural non-point source pollution management system, enhance the research and development of the law of pollutant migration and transformation, encourage the innovation of low-cost and high-benefit treatment technology, improve the construction of the management system, strengthen the collaboration of departments, increase the investment of funds, and make other suggestions so as to promote the treatment of agricultural non-point source pollution with high quality and efficiency.

Modeling the response of agricultural non-point source pollution to planting structure and fertilization level in Erhai Lake Basin under low-latitude plateau climate

Agricultural non-point source (NPS) pollution is the major contributor to pollution in the Erhai Lake Basin in northeastern China. The key to the control of NPS pollution is optimizing the planting structures and fertilization regimes. However, the interplay between the three remains unknown, and to identify their interaction is of great importance for NPS pollution control. In this study, experiments with varied crop rotations and fertilization schemes were performed in Erhai Lake Basin, based on which eight response models between the planting structure, fertilization level and NPS pollution under the low-latitude plateau climate were innovatively proposed and verified. The major findings are as follows: (1) there are six main planting structures in Erhai Lake Basin, among which rice-broad bean rotation takes up the largest area (35.72% of the total planting area), followed by corn-broad bean rotation (which accounts for 28.64% of the total area); (2) structural equation modeling reveals that in the study area, the total nitrogen (TN) was the largest contributor to agricultural NPS pollution (R2 = 0.90); while in rice-broad bean and corn-purple leaf lettuce rotations, total phosphorus (TP) was found to be the largest contributor to NPS pollution (R2 > 0.37); (3) climate, irrigation, planting structure and fertilization affected the indicators of agricultural NPS pollution, among which climate had the greatest impact on the TN content, with a path coefficient of 0.87; irrigation had the largest impact on the ammonia nitrogen (AN) content, with a path coefficient of 0.62; fertilization also had the largest impact on the TN content, with a path coefficient of 0.67; the percentage of the planting structure area affected TP (0.21), TN (0.29) and chemical oxygen demand (0.24); the crop area significantly affected the content of TP (0.45), TN (0.42) and chemical oxygen demand (0.51); and the crop yield significantly affected the content of TN (0.57). The research provides theoretical support for the prevention and control of agricultural NPS pollution in Erhai Lake Basin.

Retracted: Incentive Measures for Agricultural Nonpoint Source Pollution Control of Farmers Based on Choice Modelling: A Case Study on the Water Source Region of Xin’an River Reservoir

Retracted: Incentive Measures for Agricultural Nonpoint Source Pollution Control of Farmers Based on Choice Modelling: A Case Study on the Water Source Region of Xin’an River Reservoir

E-commerce development and its contribution to agricultural non-point source pollution control: Evidence from 283 cities in China

Agricultural non-point source (ANPS) pollution is a pressing environmental issue in developing countries that poses a substantial threat to sustainable development. With the rapid growth of e-commerce and its great penetration and transformation in many socioeconomic sectors, e-commerce plus agriculture is widely regarded as the solution to sustainable agricultural development. However, the environmental impacts of e-commerce on agriculture, as well as the underlying mechanisms have yet to be fully explored and verified. Based on China's practices of e-commerce development and its integration with agriculture, a panel dataset of 283 prefecture-level cities from 2009 to 2019 was collected, and a spatial difference in difference (SDID) model combined with a Durbin model was constructed to examine the local and spatial spillover effects of e-commerce development on ANPS pollution. It is found out that e-commerce development has significant positive environmental impacts achieved by stimulating industrial structure upgrading and promoting green technology innovation, while the mechanism of cultivation scaling up tends to aggravate the ANPS pollution. Spatial analysis demonstrates that e-commerce development also helps alleviate the ANPS pollution of neighboring regions with a decayed effect over a distance. Meanwhile, the impact of e-commerce on mitigating ANPS pollution shows regional heterogeneity. Those developed regions present significant positive effects, while those regions dominated by agriculture economy and without sufficient supporting facilities for e-commerce development, show significant negative effects. Therefore, we argue that the positive environmental contribution of e-commerce is not bound to happen but instead is contingent, while policies should be adapted to local conditions and enhanced to encourage the integration of e-commerce and other socioeconomic sectors, in order to develop beyond the immature pioneering stage.

Does Livelihood Determine Attitude? The Impact of Farmers’ Livelihood Capital on the Performance of Agricultural Non-Point Source Pollution Management: An Empirical Investigation in Yilong Lake Basin, China

Agricultural non-point source pollution is intricately connected to the rural population’s production and lifestyle. The heterogeneous composition of livelihood capital results in varied livelihood types, influencing the farmers’ attitudes and perceptions of the treatment projects. This ultimately causes discrepancies in the farmers’ evaluation of agricultural non-point source pollution control. In this study, a participatory evaluation method was employed to evaluate the performance of agricultural non-point source pollution control projects in the Yilong Lake Watershed of Yunnan Province and analyze the underlying reasons for the differing performance evaluations. The findings revealed that pure farmers’ performance evaluation value for agricultural non-point source pollution control projects in Yilong Lake Basin was 0.4811 (with the full mark being 1), with a general evaluation grade. Part-time business households had a performance evaluation value of 0.5969, also with a general evaluation grade, while non-farmers had a performance evaluation value of 0.7057, with a good evaluation grade. The performance evaluation value ranked from highest to lowest is non-farmer > part-time farmer > pure farmer. The main factor affecting the variation in farmers’ performance evaluation is the key index of different livelihood capital. If pollution control projects can promote the adjustment of farmers’ livelihood capital types, it can enhance not only the performance evaluation degree of farmers, but also the sustainability of farmers’ livelihoods and increase their adaptability to livelihood risks. Therefore, pollution control projects should consider farmers’ livelihood capital types and be implemented accurately to improve farmers’ satisfaction and sustainability.

Development of improved flow analysis prototype method for measuring and understanding agricultural non-point source (NPS) nitrogen (N) and phosphorus (P) pollution

The loss of nitrogen (N) and phosphorous (P) through continuous surface runoff by rainfall after fertilizing and leaching into groundwater has become a critical issue that causes eutrophication of rivers, lakes, and even drinking water, resulting in agricultural non-point source (NPS) pollution of up to 50 % of pollution load. Traditionally, N and P were measured using the laboratory's flow injection analysis (FIA) method before evaluating the pollution load, which could meet urgent requirements in the fast response, prevention, and control of agricultural NPS pollution. Herein, we propose an improved flow analysis (perturbation dispersion) method by integrating chemical reaction chambers to measure nitrogen and phosphorus in water automatically and continuously. The as-fabricated system was validated with real samples from Qianjiang, Hubei Province. The experimental results drew a correlation coefficient of 0.91449 for ammonium nitrogen between the existing lab-based flow analysis method and the innovative (improved) flow analysis method. The correlation coefficients of 0.99828, 0.85129, and 0.99206 for nitrate nitrogen, ammonium nitrogen, and phosphorus were calculated from the measurement results. The detection limits of 0.55, 0.20, and 0.025 mg/L with relative standard deviations (RSD) of 0.8 %, 5.7 %, and 0.9 % were observed for NH4+–N, NO3––N, and PO43− measurements, respectively. This work facilitates the online and continuous control of the NPS pollution load and timely expands the flow injection analysis (FIA) techniques for understanding the pollutants in water and farmland environments.

What influences the behavior of farmers' participation in agricultural nonpoint source pollution control?—Evidence from a farmer survey in Huai'an, China

What influences the behavior of farmers' participation in agricultural nonpoint source pollution control?—Evidence from a farmer survey in Huai'an, China

Application of riparian buffer zone in agricultural non-point source pollution control—A review

Water is an important natural element of our environment, and its management and security are also serious concerns. Agricultural non-point source pollution (NPSP) is one of the major sources of contaminants causing water quality degradation. A riparian buffer zone is a vegetative cover adjacent to water channels that positively contributes to pollutant filtration and sediment trapping. It has the potential to filter nutrients, reduce nutrients and pesticide leakage, provide habitat and protection against floods, minimize erosion issues, improve biodiversity and ecological connectivity, and add aesthetics to the area. Moreover, it is inexpensive and requires little maintenance making buffer zone an attractive approach to NPSP control. In this review, we have enlightened the effects of the riparian buffer zone on water quality and agricultural NPSP and how its structures and mechanisms contribute to controlling water pollution effectively. We conclude that the riparian buffer zone is an effective technique for water safety, NPSP control, and creating a suitable environment for terrestrial and aquatic species. Moreover, it has the potential to reduce the water temperature due to the shading effect and sustain water habitat acting as a climate adaptation tools. Buffer zones should be adopted for agricultural non-point source pollution and achieve environmental sustainability. However, the long-term influence of the riparian buffer zone on trapping NPS pollutants, soil properties, and groundwater quality is s research gap.

Research on multiple co-governance of agricultural non-point source pollution in China on the perspective of ENGOs and public participation.

Effective prevention and control of agricultural non-point source pollution is a major challenge faced by the Chinese local government in the context of rural revitalization, and clarifying the game relationship between stakeholders in agricultural non-point source pollution control actions will help achieve multiple co-governance better. Accordingly, this paper discusses the interactive decision-making relationships between local government and livestock and poultry breeding enterprise (LPBE) under the participation of Environmental non-government organizations (ENGOs) and public, by constructing an evolutionary game model, as well as analyzing evolutionary cooperative stability strategies and realizing the simulation of evolution processes in different scenarios by MATLAB. The results show that government subsidy has an incentive effect on LPBE to adopt the purifying strategy, yet reduces the enthusiasm of local government for supervision. Improving the participation degree and right space of ENGOs is conducive to the realization of multiple co-governance models. Furthermore, the impact of public participation on multiple co-governance of agricultural non-point source pollution is related to the local government's investigation rate and the public reporting fairness; strengthening the local government's supervision capacity and improving the public reporting fairness can achieve better collaborative governance effects.

Dynamic evolution and decoupling analysis of agricultural nonpoint source pollution in Taihu Lake Basin during the urbanization process

In recent years, as control of industrial point source pollution has gradually increased, agricultural nonpoint source pollution (ANPSP) has become an important focus of water pollution control. ANPSP is closely related to challenges in the urbanization process, though urbanization has mitigated water pollution control to a certain extent. In this study, taking the Taihu Lake Basin of China as an example, the dynamic interrelation between urbanization and ANPSP is macroscopically displayed by the Vector autoregressive (VAR) model, and the coevolution characteristics of the two are quantitatively measured by the decoupling index. Then, the Logarithmic Mean Divisia Index (LMDI) decomposition method is used to explore the influence of urbanization's accompanying effects, including pollution intensity, economic structure, output level and population factors, on ANPSP. The results showed that (1) since 2006, total nitrogen (TN) has continued to decline, while total phosphorus (TP) initially increased then decreased. The main pollution sources were livestock and poultry breeding and planting, which showed a trend of alternating growth and decline. At the same time, the contributions of rural life and aquaculture to pollution gradually increased. (2) Urbanization has a positive effect on ANPSP control after reaching a certain stage, but there is a possibility of pollution rebound; urbanization mitigates ANPSP, but still contributes to environmental pollution. (3) The decoupling between urbanization and ANPSP is achieved across the basin. However, the decoupling level between TP and urbanization lagged behind the decoupling level between TN and urbanization. Meanwhile, the spatiotemporal heterogeneity of the TP decoupling index is more evident than that of the TN index. (4) The intensity effect and structure effect promote the strong decoupling between urbanization and ANPSP, while the output effect and population effect make the decoupling relationship evolve to adverse states such as expansive negative decoupling and expansive coupling.

Analysis of the Development Trend in Agriculture Non-point Source Pollution Based on CiteSpace

This paper uses CiteSpace to visualize and analyze the literature related to agricultural non-point source pollution in China Knowledge Network (CNKI) from 1993~2022. The results showed that the research on agricultural non-point source pollution has gone through three stages: the beginning (1993~2006), booming development (2007~2011), and stable development (2011-2022). The research on agricultural non-point source pollution focuses mainly on agricultural non-point source pollution, pollution control, and model simulation. Agricultural non-point source pollution has always played a leading role in the development of the research field since the research until now, and model simulation and spatial distribution have been continuously cited from the emergence of clustering until now, and are widely available in the research field.

Coupling coordination and spatiotemporal dynamic evolution of the water-energy-food-land (WEFL) nexus in the Yangtze River Economic Belt, China.

The interrelationship between regional water, energy, food, and land systems is extremely complex. Hence, accurately assessing the coupling coordination relationship and identifying the influential factors of the water-energy-food-land nexus (WEFL nexus) are of utmost importance. This study proposes a novel analytical framework and evaluation index system for exploring interactions across the WEFL nexus. The comprehensive benefit evaluation index (CBEI), coupling coordination degree (CCD) model, and obstacle factor diagnosis model are integrated to assess and analyze the coupling coordination relationship and spatiotemporal dynamic evolution of the WEFL nexus in the Yangtze River Economic Belt (YREB) from 2006 to 2020. The results indicated that (1) the CBEI and CCD generally increased from 0.23 to 0.79 and 0.45 to 0.88, respectively, revealing the upward trend of the coordination development levels of the WEFL nexus in the YREB. (2) The lower reaches achieved a relatively higher coordination development degree than the upper and middle reaches of the YREB. (3) The findings of obstacle factors reveal that agricultural non-point source pollution control, waterlogging disaster prevention, industrial solid waste efficient treatment, and urban water-saving are the essential fields that need to be improved in YREB's future development. This study helps to understand the complex interrelation of the WEFL nexus at different spatial-temporal scales and provides a novel framework that can be used as an evaluation system and policy insights for a region's integrated resources, environmental management, and green sustainable development.

Research on the Relationship between Urban Agricultural Nonpoint Source Pollution and Rural Residents' Income Growth.

Researching the relationship between urban agricultural nonpoint source pollution (UANSP) and increases in rural residents' income levels has significant practical implications for effectively controlling UANSP and improving the quality of life of urban residents, and it is conducive to achieving a win-win situation between economic and environmental benefits. This study chooses agricultural statistical data from Shanghai from 1998 to 2019, implements the EKC and the VAR model to dynamically analyze internal interaction between them, and thoroughly examines impact effect and explanatory contribution degree of each variable. The results show the following: (1) There was an inverted “N” curve between plastic film application intensity and rural residents' per capita disposable income; there was a linear decreasing relationship between the intensity of fertilizer and pesticide application and rural residents' per capita disposable income. (2) Nonpoint source pollution emissions will decrease as rural residents' income levels rise. Reduction of nonpoint source pollution can promote the short-term improvement of rural residents' income levels, but it has a negative effect on the long-term improvement of rural residents' income levels. (3) Fertilizer and pesticide application intensity had a low driving effect on rural residents' income growth, whereas plastic film application intensity had a strong driving effect. Therefore, the ANSP of Shanghai should be treated from both long-term and short-term perspectives on the basis of decreasing stage. In the long term, the government should increase farmers' sense of ownership in agricultural nonpoint source pollution control, prioritize the development of ecological circular agriculture, and gradually improve nonpoint source remote sensing monitoring and service management capabilities. In the short term, the government should reduce farmers' nonpoint source pollution through subsidies and technical assistance. To keep costs down, the government established an administrative reward and punishment system to control ANSP at the source.

Estimation of Agricultural Non-point Source TN and TP Export Coefficients Based on Soil Loss

Taking the Yellow River Delta as a typical research area, we constructed a coastal agricultural TN and TP non-point source pollution estimating model by analyzing the relationship between the surface soil pollutant loss risks and the monitored pollutant flux into the sea. On this basis, TN and TP non-point source export coefficients of paddy fields, irrigated land, and dry land were calculated, and the verification showed that the estimated export coefficients were acceptable. In the study area, the TN and TP export coefficients into the sea of arable land were 18.33 kg·(hm2·a)-1 and 1.02 kg·(hm2·a)-1, respectively. The agricultural non-point source pollution loads of arable land were relatively high in summer. The sub-basins with larger agricultural non-point source pollution loads were mainly located in the control areas of the Zhimai River, Guangli River, and Xiaodao River. The administrative regions with larger total agricultural TN and TP loads were mainly in the northern Huanghekou Town and Yong'an Town, and areas with larger loads per unit area were in the southwest. Therefore, it is necessary to pay more attention to the temporal effects of agricultural non-point source pollution, simultaneously coordinate the social and economic development, and formulate comprehensive agricultural non-point source pollution prevention and control strategies from the perspective of sub-basins and administrative units. This will allow us to improve the offshore pollution status from the perspective of land and sea coordination.