Progress in the research on aquatic environmental nonpoint source pollution in China

In this paper, the authors reviewed the development process of China's research on aquatic environmental nonpoint pollution, and the situation of nonpoint source pollution in east China was also analyzed.

Estimation of ammonia nitrogen load from nonpoint sources in the Xitiao River catchment, China

Ammonia nitrogen (NH4+-N) is one of the three main forms of total nitrogen (TN). Most studies have estimated the load of TN from nonpoint sources instead of one specific form. The relationship between land use and concentrations of NH4+-N in runoff was analyzed using the hydraulic analysis functions of a Geographic Information Systems (GIS), and the annual loads of NH4+-N in the Xitiao River catchment were estimated according to model results. The results suggested that the calculated annual loads of NH4+-N...

Modelling spatial variation in the treatment costs of nonpoint source pollution in mountainous regions of southwest China

Non-point source(NPS) pollution is considered to be one of the main threats of the aquatic environment. Mountainous regions are particularly important water sources for urban areas. The various driving factors of NPS pollution such as terrain, precipitation, and vegetation type in mountainous regions show clear spatial heterogeneity. Consequently, the management systems required for NPS pollution in mountainous regions are complex. In this study, we developed a framework to estimate and map the treatment costs for NPS pollution in mountainous regions and applied this method in Baoxing County, a typical mountainous county in Sichuan Province of southwest China. The export levels of total nitrogen(TN) and total phosphorus(TP) in Baoxing County were estimated using the water purification model in InVEST(Itegrated Valuation of Ecosystem Services and Tradeoffs) tool. NPS pollutant treatment costs were calculated based on the level of pollutants exports, water yield, water quality targets, and treatment costs of NPS pollutants per unit mass. The results show that at the watershed level the amounts of TN and TP exported in Baoxing County were below threshold limits. However, at the sub-watershed level, TN and TP excesses of 291.64 and 2.96 tons per year were found, respectively, with mean TN and TP treatment costs of 6.58 US$/hm^2 and 0.35 US$/hm^2. Appraising pollution treatment cost intuitively reflects the overall expenditure in NPS pollution reduction from an economic perspective. This study provides a foundation for the implementation of Payment for Ecosystem Service(PES) and the prevention and control of NPS pollution.

Identifying Nonpoint Sources of Phosphorus and Nitrogen: A Case Study of Pollution That Enters a Freshwater Wetland (Laguna Cartagena, Puerto Rico)

Point and nonpoint sources of phosphorus (P) and nitrogen (N) can cause reductions in water quality, including eutrophication. Nonpoint pollution represents a special challenge because of dispersed not easily identifiable sources such as the runoff from soil, nutrients, and other chemicals from agricultural fields and residential areas. Laguna Cartagena is a tropical freshwater wetland, situated in southwestern Puerto Rico. It is a eutrophic ecosystem, and its eutrophication is caused by both external nutrient loading and internal, mainly by phosphorus. This wetland has been affected by phosphorus loading from inorganic agricultural fertilizer in this historically oligotrophic wetland system until the end of subsidized fertilizer use and sugar cane cultivation in the late 1990s. This study identifies: 1) nonpoint sources of phosphorus (SRP, Soluble Reactive Phosphorus and TP, Total Phosphorus) and nitrogen (nitrate, nitrite, and ammonia) that enter Laguna Cartagena;and 2) the role of precipitation events on the contributions of phosphorus and nitrogen loading to ecosystems. Herein we assess water samples from five channelized external sources of P and N that enter Laguna Cartagena at two-week intervals from October 2013 through November 2014. Rainfall data were obtained weekly from a rain gauge. Standard methods were used for all chemical analyses. Results showed that the channelized waterways that carry water to the lagoon can be classified as hypereutrophic (>100 μg/L) for TP concentrations and oligotrophic (<200 μg/L) for nitrogen concentrations. Currently agriculture (rice and cattle) is the predominant land use at the nearby University of Puerto Rico (UPR) Lajas Agricultural Experiment Substation, the predominant nonpoint source of nutrient pollution (SRP, TP and ammonia) in the principal channelized water sources to the lagoon. Current nutrient loads are likely derived from fertilizers applied to the Substation’s rice fields, and a high density livestock. The second important cause of external surface water degradation (SRP, TP and ammonia) is the discharge from rural households in the drainage basin that discharge greywater directly to the environment, as indicated by the results from Cerro Alto hills immediately to the north of the lagoon. Precipitation also was associated with SRP, TP and ammonia loads.

Study on Control Scheme for Nonpoint Source Pollution in Dahe Reservoir Water Source Protection Area of Dianchi Lake Basin

[ Objective] The research aimed to study control scheme for nonpoint source pollution in Dahe Reservoir water source protection area of Dianchi Lake basin.[ Method] On the basis of the SPOT5 satellite remote sensing imagery in 2010 and field investigation of GPS record, ecological design for nonpoint source pollution control in Dahe Reservoir water source protection area of Dianchi Lake basin was conducted. Then, the effects of optimization measures were evaluated by the reductions of N and P outputs on different land-use types. E Resultl Control functions of the water source protection area on soil erosion and the emissions of N, P and other pollutants would be promoted after optimization. The optimization meas- ures had a significant effect for prevention and control of the non-point source pollution in the water source protection area. [ Conclusion] The re- search provided scientific basis for promoting ecological construction of the small green basin in Dahe Reservoir water source protection area of Di- anchi Lake basin.

Development of a Hybrid Best Management Practice System for Control of Agricultural Nonpoint Water Pollution

Agricultural drainage ditches play an important role in removing surplus water;however, these can also potentially act as major conduits of agricultural nonpoint source pollutants, including sediment, nitrogen, and phosphorus. A supplementary hybrid system to limit such pollution was developed in this study;this consists of biodegradable fiber check dams, used in combination with a synthetic polymer (Polyacrylamide, PAM). An open channel experiment was conducted to optimize the design of the hybrid system, taking into account a variety of physical and hydraulic conditions. Subsequent field application of the hybrid system improved runoff water quality, such as 10.0% to 98.3% reduction for suspended solids, 25.2% to 98.4% reduction for turbidity, 21.1% to 91.1% increase for BOD, 19.2% to 75.4% increase for COD, 21.0% to 73.3% reduction for T-N, 5.9% to 91.2% reduction for T-P and 35.7% to 97.6% reduction for fecal coliforms. This clearly showed that this hybrid system could play a significant role in supplementing conventional best management practices.

Assessment of Point and Nonpoint Sources Pollution in Songhua River Basin,Northeast China by Using Revised Water Quality Model

Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin.It is difficult to identify the sources and to quantify the load, especially in modeling nonpoint source.In this study a revised model was established by integrating point and nonpoint sources into one-dimensional Streeter-Phelps(S-P) model on the basis of real-time hydrologic data and surface water quality monitoring data in the Jilin Reach of the Songhua River Basin.Chemical oxygen demand(COD) and ammonia nitrogen(NH 3-N) loads were estimated.Results showed that COD loads of point source and nonpoint source were 134 958 t/yr and 86 209 t/yr, accounting for 61.02% and 38.98% of total loads, respectively.NH 3-N loads of point source and nonpoint source were 16 739 t/yr and 14 272 t/yr, accounting for 53.98% and 46.02%, respectively.Point source pollution was stronger than nonpoint source pollution in the study area at present.The water quality of upstream was better than that of downstream of the rivers and cities.It is indispensable to treat industrial wastewater and municipal sewage out of point sources, to adopt the best management practices to control diffuse pollutants from agricultural land and urban surface runoff in improving water quality of the Songhua River Basin.The revised S-P model can be successfully used to identify pollution source and quantify point source and nonpoint source loads by calibrating and validating.

Study on Management and Control of Nonpoint Source Pollution from Urban Surface Runoff

Urbanization is the dominant form of land-use change in terms of impacts on water quality, hydrology, physical proper- ties of watersheds and their nonpoint source (NPS) pollution po- tential at present. Urbanization has changed the source, process and sink of urban NPS pollution, especially raised the pollution load of urban runoff NPS in receiving water. Urban runoff pollu- tion is a hot spot of research on NPS. This paper analyzed type, source and harm of the NPS pollutants of urban runoff and its influence on the receiving water. Through estimating NPS pollu- tion load of urban runoff and summarizing the law and character- istics of urban runoff NPS systemically, study on management and control of urban runoff NPS pollution was focused on the applica- tion of BMPs (best management practices). It is a fresh method- ology that management and control on NPS pollution from urban surface runoff was analyzed by methods of landscape ecology, environmental economics and environmental management. The paper provided a scientific reference for mitigating urban water environment pressure and an effective method for management and control of NPS pollution from urban surface runoff..

ECONOMIC APPROACH FOR CONTROL AGRICULTURAL NONPOINT SOURCE POLLUTION IN CHINA

This paper mainly discusses the feasibility to establish economic policy systems for control and management of agricultural nonpoint source pollution in China. The current situation of serious agricultural nonpoint source pollution in China is described firstly. Based on the environmental policy and economics theories, the system of economic policies for control and management of agricultural nonpoint source pollution is designed in this paper. This system includes the policy objective, the designing principle and the methods. The key issues include pollution charge, inputs tax for restriction, subsides for induction and incentive, effluent trading for least cost reduction. The emphases are optimized on inputs tax and agricultural chemical tax permit under complete information, as well as sub-optimized inputs tax under incomplete information, subsides for farm due to positive and negative externality. The functions and suitability of the policies are also analyzed in the paper. According to the field experiment results and other relating economic data in watershed of the Chaohe River, Beijing, some economic approaches to reducing agricultural nonpoint source pollution are proposed. The main idea is to encourage and support the farmers to improve their farming way, and to implement the policy of castigating charge simultaneously. The feasibility of the policies are analyzed with consideration of economy, technology and institution. It is concluded that the economic policies are necessary and feasible.

Calculation of Intercepted Volume of Sewer Overflows: a Model for Control of Nonpoint Pollution Sources in Urban Areas

The authors discovered large differences in the characteristics of overflows by the calculation of 1) intercepting volume of overflows for sewer systems using SWMM model which takes into consideration the runoff and pollutants from rainfalls and 2) the intercepted volume in the total flow at an investigation site. The intercepting rate at the investigation point of CSOs showed higher values than the SSDs. Based on the modeling of the receiving water quality after calculating the intercepting amount of overflows by considering the characteristics of outflows for a proper management of the overflow of sewer systems with rainfalls, it is clear that the BOD decreased by 82[KG-*3].9%-94.0% for the discharge after intercepting a specific amount of flows compared to the discharge from unprocessed overflows.

A WEPp-Water Quality model for simulating nonpoint source pollutants in nonuniform agricultural hillslopes:Model development and sensitivity

The Water Erosion Prediction Project(WEPP)model code was modified extensively to support the simulation of nonpoint source(NPS)pollutant sourcing and transport in nonuniform hillslopes based on NPS science from the Soil and Water Assessment Tool(SWAT).This was accomplished utilizing WEPP's overland flow element(OFE)in place of SWAT's hydrologic response unit(HRU)construct which enabled more physically plausible routing within a hillslope.In addition,several improvements to the NPS code base were implemented.These include:free-source format,modern-Fortran conventions,minor enhancements to NPS model science,and code refactoring.This manuscript documents all model development activities,presents a comparison of relevant WEPP and WEPP-WQ code bases,and performs a local sensitivity analysis of the final model code for the most important input parameters and processes.Sensitivity results indicated that the model performed as expected according to its design and provided important insights for potential subsequent validation studies.

不同配置乡村植被缓冲带阻控径流污染特征研究

植被缓冲带是河湖的重要生态空间屏障,对于减缓人类活动对河湖的直接干扰、阻隔农业面源污染等具有重要意义。为系统研究不同类型缓冲带对农田氮磷等污染物的拦截功效,本研究在定远张山设计8个缓冲带小区,结合自然降雨方式,持续两年观测不同缓冲带对地表径流及其主要污染物(TN、TP、COD)的削减效果。结果表明:林地和3°、8°横垄耕地缓冲带对径流的拦截效率较高,减流率分别达到了62.4%、52.0%和60.6%,径流量随雨强增大先升高后下降。与8°坡耕地缓冲带相比,降坡(3°)处理竖垄、横垄缓冲带泥沙流失量分别降低53.3%、50.9%。降雨产流的养分流失以氮素和有机质为主,林地缓冲带对径流NH4+-N的拦截率平均高达95.2%,此外降坡和横垄耕作措施也能有效减少径流冲刷的氮素流失。不同处理缓冲带对径流TP均有较好的拦蓄效果。3°、8°横垄耕地缓冲带CODMn流失量较低,拦截率达到53.0%、58.6%。林地缓冲带中高覆盖度的植被和发达的根系能够有效减缓降雨对地表的冲刷,减少径流和养分流失。在南方丘陵山地的乡村地区实施横坡垄作是拦蓄径流、降低面源污染风险的有效措施。

Spatiotemporal characteristics of cultivated land use eco-efficiency and its influencing factors in China from 2000 to 2020

Improving cultivated land use eco-efficiency(CLUE)can effectively promote agricultural sustainability,particularly in developing countries where CLUE is generally low.This study used provincial-level data from China to evaluate the spatiotemporal evolution of CLUE from 2000 to 2020 and identified the influencing factors of CLUE by using a panel Tobit model.In addition,given the undesirable outputs of agricultural production,we incorporated carbon emissions and nonpoint source pollution into the global benchmark-undesirable output-super efficiency-slacks-based measure(GB-US-SBM)model,which combines global benchmark technology,undesirable output,super efficiency,and slacks-based measure.The results indicated that there was an upward trend in CLUE in China from 2000 to 2020,with an increase rate of 2.62%.The temporal evolution of CLUE in China could be classified into three distinct stages:a period of fluctuating decrease(2000-2007),a phase of gradual increase(2008-2014),and a period of rapid growth(2015-2020).The major grain-producing areas(MPAs)had a lower CLUE than their counterparts,namely,non-major grain-production areas(non-MPAs).The spatial agglomeration effect followed a northeast-southwest strip distribution;and the movement path of barycentre revealed a"P"shape,with Luoyang City,Henan Province,as the centre.In terms of influencing factors of CLUE,investment in science and technology played the most vital role in improving CLUE,while irrigation index had the most negative effect.It should be noted that these two influencing factors had different impacts on MPAs and non-MPAs.Therefore,relevant departments should formulate policies to enhance the level of science and technology,improve irrigation condition,and promote sustainable utilization of cultivated land.

流域面源污染研究进展与展望

面源污染已成为影响流域水环境和水安全的重要来源,是当前国内外学者关注的热点之一,同时也是最具挑战性的研究领域之一。科学高效地治理面源污染问题已经纳入国家战略计划。因此,在新形势和政策背景下如何推进面源污染研究工作,以保障流域水环境可持续发展已成为紧迫任务。本文较为全面地回顾和总结了我国面源污染研究现状,归纳了主要研究方法和典型治理措施,并基于研究中存在的主要问题,结合我国水污染治理现状给出相应建议,指出未来发展趋势。本文可为面源污染的全过程监管、评估及治理提供重要参考,有助于完善我国水污染治理体系。

Modeling the effects of constructed wetland on nonpoint source pollution control and reservoir water quality improvement

This article describes the integrated modeling approach for planning the size and the operation of constructed wetlands for maximizing retention of nonpoint source pollutant loads and reservoir water-quality improvement at a catchment scale. The experimental field-scale wetland systems （four sets, 0.88 ha each） have been in operation since 2002, where water depth was maintained at 30-50 cm and hydraulic loading rate was at 6.3-18.8 cm/day. The wetland system was found to be adequate for treating polluted stream water with stable removal efficiency even during the winter. The integrated modeling system （modified-BASINS） was applied to the Seokmoon estuarine reservoir watershed and calibrated with monitoring data from constructed wetland, stream, and reservoir. The calibrated integrated modeling system estimated that constructing wetlands on 0.5% （about 114 ha） of the watershed area at the mouth of reservoir could reduce 11.61% and 13.49% of total external nitrogen and phosphorus loads, respectively. It also might improve the nitrogen and phosphorus concentration of the reservoir by 9.69% and 16.48%, respectively. The study suggested that about 0.1%-1.0% of the watershed area should be allocated for constructed wetland to meet specified water-quality standards for the estuarine reservoir at the polder area where land use planning is relatively less complicated.

Predicting the impacts of climate change on nonpoint source pollutant loads from agricultural small watershed using artificial neural network

This study described the development and validation of an artificial neural network （ANN） for the purpose of analyzing the effects of climate change on nonpoint source （NPS） pollutant loads from agricultural small watershed. The runoff discharge was estimated using ANN algorithm. The performance of ANN model was examined using observed data from study watershed. The simulation results agreed well with observed values during calibration and validation periods. NPS pollutant loads were calculated from load-discharge relationship driven by long-term monitoring data. LARS-WG （Long Ashton Research Station-Weather Generator） model was used to generate rainfall data. The calibrated ANN model and load-discharge relationship with the generated data from LARS-WG were applied to analyze the effects of climate change on NPS pollutant loads from the agricultural small watershed. The results showed that the ANN model provided valuable approach in estimating future runoff discharge, and the NPS pollutant loads.

Nanomaterials for environmental burden reduction,waste treatment,and nonpoint source pollution control:a review

Nanomaterials are applicable in the areas of reduction of environmental burden,reduction/treatment of industrial and agricultural wastes,and nonpoint source(NPS)pollution control.First,environmental burden reduction involves green process and engineering,emissions control,desulfurization/denitrification of nonrenewable energy sources,and improvement of agriculture and food systems.Second,reduction/treatment of industrial and agricultural wastes involves converting wastes into products,groundwater remediation,adsorption,delaying photocatalysis,and nanomembranes.Third,NPS pollution control involves controlling water pollution.Nanomaterials alter physical properties on a nanoscale due to their high specific surface area to volume ratio.They are used as catalysts,adsorbents,membranes,and additives to increase activity and capability due to their high specific surface areas and nano-sized effects.Thus,nanomaterials are more effective at treating environmental wastes because they reduce the amount of material needed.

农业面源污染治理行为的演化博弈分析

农业面源污染已成为制约我国农业可持续发展的重要因素,为了有效剖析其内部影响机理。本研究从地方政府与农民两大博弈主体的行为互动入手,在假设参与主体均为有限理性的前提下,将进化博弈理论应用于地方政府与农民,构建了双方的演化博弈模型,通过分析双方的复制动态方程,得到了两种稳定的演化策略,并进行数值模拟分析,探讨博弈双方的策略稳定性以及各因素对策略选择的影响。研究得出:经济系数权重对地方政府策略选择的影响大于环境质量权重,并且权重提升对农户策略选择产生的影响效果不同;减少地方政府监管成本支出有利于提升农户积极治理农业面源污染的概率;地方政府对农户的处罚与激励都会对农户决策产生影响,但是合理的政策才能使地方政府与农户偏向最优均衡。

笋溪河面源污染及其与河岸带土壤有机碳、氮、磷的关系

[目的]分析水体和河岸带土壤氮磷的空间异质性,探讨河岸带土壤有机碳、氮、磷含量对水体面源污染的影响程度,为明晰重庆笋溪河水体面源污染状况及其与河岸带土壤的关系提供理论依据。[方法]沿笋溪河采集水样44个、0—20与20—40 cm土层土样各44个,采用内梅罗指数评价了笋溪河水质污染状况,并运用方差分析和多重比较、独立样本t检验、相关性分析和冗余分析等方法研究了河岸带水体不同形态氮、磷,土壤有机碳与氮、磷总量和有效量的空间分布特征,以及水体氮、磷对土壤有机碳与各形态氮、磷及化学计量比的响应。[结果](1)笋溪河水体严重污染,且下游污染较上、中游严重;(2)笋溪河下游水体总氮、总磷和可溶性磷酸盐极显著高于上、中游,下游硝酸盐氮极显著高于中游(p<0.01);(3)下游20—40 cm土层土壤有机碳含量显著高于中游,两个土层土壤有效磷和20—40 cm全磷在各河段间差异显著,而20—40 cm C/P和0—40 cm N/P在上游均显著高于中、下游(p<0.05);0—20 cm土壤有机碳、全氮、硝态氮、全磷和有效磷含量均显著高于20—40 cm(p<0.05),表聚现象明显;(4)相关性分析显示水体各形态氮和总磷与土壤全磷和有效磷呈显著正相关(p<0.05),冗余分析表明土壤有机碳与各形态氮、磷及化学计量比对水体各形态氮、磷的总解释率达64.15%,土壤全磷和有效磷是影响水体面源污染的主导因子。[结论]笋溪河面源污染严重,土壤全磷和有效磷可显著影响水体污染状况,面源污染治理应重点关注河岸带生态系统。