Point Source Pollution Control Research Articles

Load quantification and effect evaluation of urban non-point source pollution in the Licun River based on SWAT model.

With the gradual control of point source pollution, the impact of urban nonpoint source pollution on river water quality is becoming more prominent. Regarding the current problem that nonpoint source pollution loads in urban basins are difficult to quantify and the impact on water quality is difficult to analyze, the Licun River basin in Qingdao was selected as the research object. Through the field survey and surface accumulation sampling analysis of the basin, the evaluation model of urban nonpoint source pollution was constructed by revising the land type data of the basin and the urban database of the SWAT model. The results showed that concentration of nitrate in precipitation was most sensitive to the simulation of nitrogen loading; organic P in baseflow was most sensitive to the simulation of phosphorus loading. The Nash-Sutcliffe efficiency coefficient (ENS) and the coefficients of determination (R2) of the SWAT model for runoff, total phosphorus (TP), and total nitrogen (TN) in the simulation validation period meet the model requirements,indicating a good model fit. In addition, the spatial and temporal distribution characteristics of urban nonpoint source pollution of TN and TP in 2021 were analyzed. In July, rainfall-runoff from the Licun River basin was the most polluted.

The global progress on the non-point source pollution research from 2012 to 2021: a bibliometric analysis

BackgroundWith effective control of point source pollution, non-point source (NPS) pollution has been widely concerned as the primary reason for the improvement of global water environmental quality. Some bibliometric analysis related to NPS pollution has been carried out before the mid-2010s. Analyzing the research status and hot issues of NPS pollution in the past decade is important for guiding the control and management of NPS pollution in the future.ResultsA bibliometric analysis was conducted based on 3407 publications retrieved from the Web of Science during 2012–2021. China, USA and UK were the most productive countries. Sci. Total Environ, Environ. Sci. Pollut. Res, and Water were the most productive journals. The NPS pollutant, pollution types, driving forces, technology and the research object were retrieved from the keywords analysis. The common NPS pollutants of nitrogen, phosphorus, and heavy metals grabbed the highest attention, while the emerging contaminants have attracted increased attention. The migration and transformation of agricultural NPS pollution and urban NPS pollution driven by climate change and land use change were hot issues related to NPS pollution studies. Technologies related to the combination of 3S technology (RS, GIS, and GPS) and NPS pollution models, the sustainable control technologies, the technology of accurate traceability and automatic monitoring, and the comprehensive management plan were the important research areas related to NPS pollution. Although the research locations were mostly concentrated in the surface water and groundwater, the ocean and drinking water have great potential for future research.ConclusionsThis study illustrates the global focuses related to NPS pollution during 2012–2021 according to analyzing the publication outputs, source journals, source country, author, institution and the high-frequency keywords. Results demonstrated that the migration and transformation mechanism and ecological risk assessment for heavy metals and emerging pollutants, accurate traceability techniques, sustainable ecological restoration control techniques, and marine pollution have attracted rising attention. Additionally, developing countries will have a higher interest in NPS pollution in the future, because developed countries have already made great progress in controlling NPS pollution.

Long-term riverine nitrogen dynamics reveal the efficacy of water pollution control strategies

Identification of long-term water quality trends in response to watershed anthropogenic interventions is crucial for developing and adapting water pollution control strategies. This study represents the first use of the Weighted Regressions on Time, Discharge, and Season (WRTDS) model to evaluate trends and sources of riverine nitrogen (N) levels over the 1980–2019 period in the Yongan River watershed of eastern China. The WRTDS model showed satisfactory accuracies for predicting daily riverine total N (TN), NH4+ and NO3− concentrations/loads (R2 > 0.55, n = 366). Modeled flow-normalized riverine NH4+ concentration increased by 789% from 1980 to 2009 and then decreased by 63% in 2010–2019. This changing trend for riverine NH4+ concentration was mainly attributed to a 43% decrease of wastewater NH4+ discharge load in 2010–2019 due to establishment of three new WWTPs in urban areas and enhanced rural domestic sewage collection/treatment. Although chemical N fertilizer use decreased by 49% and domestic animal numbers decreased by 73% in 2000–2019, flow-normalized riverine TN and NO3− concentrations progressively increased by 161% and 232% in 1980–2019, respectively. The paradox between decreasing N inputs and increasing riverine TN/NO3− concentrations is attributed to inputs of legacy N from soil and groundwater. This is supported by the 3.8-fold increase of riverine NO3− concentration in 1980–2019 (86% increase in 2000–2019) following 10-days with no-precipitation (representing groundwater contributions to baseflow) and a 4.1-fold increase of riverine NO3− concentration in 1980–2019 (91% increase in 2000–2019) following the first rainstorm after 10-days of no-precipitation (representing soil flushing). These results document that point-source pollution control efforts were effective, whereas benefits from nonpoint-source pollution control were masked by inputs from legacy N pollution. The WRTDS model was demonstrated to be a useful tool for assessing long-term riverine N pollution dynamics and sources, thereby providing decision-makers with critical information to guide watershed N pollution control strategies.

The characteristics of rainfall runoff pollution and its driving factors in Northwest semiarid region of China - A case study of Xi'an

With the effective control of point source pollution, rainfall runoff pollution has become the main source of water pollution in Xi'an. Understanding the characteristics and driving factors of rainfall runoff pollution would provide theoretical foundation for urban rainfall runoff pollution control. In this study, a total of 32 rainwater samples, 604 roof runoff samples and 608 road runoff samples obtained from literature and a total of 35 rainwater samples, 127 roof runoff samples and 70 road runoff samples collected by our group were mixed to analyze the rainfall runoff pollution from 2008 to 2019. The Mann-Kendall and Logarithmic Mean Divisia Index (LMDI) method were used to determine the trend of pollution and the driving factors of water quality changes. The results showed that the major pollutant from rainwater was nitrogen, while the main pollutants from roof and road runoff were COD and SS. The rainwater quality during the study period was “clean to slightly polluted”. The roof runoff quality of most years (67%) was “clean to slightly polluted”. The road runoff quality was poor: 22% was “moderately polluted”, and 45% was “heavily polluted”. The concentration of pollutants except COD in rainwater showed a decreasing trend, while the trend of pollutants in roof and road runoff was not completely consistent with that in rainwater. NH3-N showed strong positive correlation with TN in roof runoff, which indicated common sources of these pollutants. There was a significant correlation between SS and COD in road runoff, and between SS and TP in roof runoff, suggesting SS was an important carrier of COD and TP. Technology innovation was the dominant factor affecting water quality, followed by industrial structure. Economic development and population scale contribute negatively to water quality improvement, and there was a sharp increase in the population scale effect in 2017.

Systematic treatment of urban river pollution

Urban river pollution is one of the most prominent environmental problems in Chinese cities that have been trying to prevent and control. The aim of this paper is to propose an urban river governance framework from the perspective of systematic governance. The point source pollution control is the premise of river regulation. Increased impervious surface in urban areas due to urbanization continuously increases the concentration of stormwater runoff pollutants. Many low-impact development facilities such as sunken lawn and rain gardens can also effectively reduce with non-point source pollution. Controlling the pollution source eliminates some pollutants in the river though it does not improve its own ecosystem. Since the self-purification ability of an unstable ecosystem is weak, the restoration of ecosystems is critical component of the water environment management. Urban river regulation should focus on sustainable management of river sources to meet the human needs, while ensuring the health and continuous development of river ecosystems, water ecology, water landscape and water culture.

Long-Term Effects of Anthropogenic Factors on Nonpoint Source Pollution in the Upper Reaches of the Yangtze River

With the continuous enhancement of point source pollution control, non-point source (NPS) pollution has become an important factor in the deterioration of surface water quality. Meanwhile, due to the soaring global population, long-term effects of anthropogenic factors on non-point source pollution in large river basins have increasingly attracted worldwide attention. The Yangtze river is the largest river basin of China, and protecting its ecological environment has great significance on protecting the lifeline of the entire Yangtze river. In this study, the improved output coefficient and nutrient losses empirical model were used to conduct space–time simulations of non-point source pollution in the upper reaches of the Yangtze river (URYR) based on GIS during 1960–2003. This method reveals the anthropogenic effects of non-point source pollution in the upper reaches of the Yangtze river. The results indicate that the impacts of anthropogenic factors on dissolved pollutants increased significantly, while those on sediment and adsorbed pollutants increased first and then decreased during the simulation year. Agricultural land use and atmospheric deposition, as well as rural life, were the main sources of dissolved pollutants. In addition, dry land and paddy fields were the major sources of sediment and adsorbed pollutants. For the load intensities, the long-term effects of anthropogenic factors on dissolved pollutants increased rapidly, and those on the load intensity of sediment and adsorbed pollutants increased first and then decreased. Therefore, the study would propose some corresponding environmental management measures to strengthen environmental protection and non-point source pollution control in the upper reaches of the Yangtze river.

Heavy metal pollution in reservoirs in the hilly area of southern China: Distribution, source apportionment and health risk assessment

Reservoirs play more and more important role in providing potable water in many developing countries, including the China. In the present study, pollution characteristics, source and health risk of dissolved heavy metals in 19 representative reservoirs in the hilly area of southern China were investigated. The results presented great spatial heterogeneity in heavy metal concentrations among the studied reservoirs due to the disturbances by different anthropogenic activities. Several reservoirs had significantly higher concentrations of heavy metals compared with others, FengTan (FT) reservoir (0.34μg/L in dry season), Cr in reservoirs of HuangShi (HS) and ZheLin (ZL) with values of 4.16μg/L and 3.45μg/L in dry season respectively, and Al in reservoirs of JiaoKou (JK), GuTian (GT) and DouShui (DS) with values of 1011μg/L, 1036μg/L and 1001μg/L in wet season, respectively. Furthermore, there was a great difference in the seasonal variation of heavy metals, especially for Al and Pb in wet season characterized with relatively high values of 643μg/L and 0.67μg/L, respectively. Accordingly, Al was identified with a great health risk to living beings in view of its mean value in wet season, which greatly exceeded the criteria for drinking water of China, WHO and US EPA. Furthermore, As might be the greatest concern of health risk in this region considering its high carcinogenic risk to the local residents around the reservoirs of OuYangHai (OYH), DS, ZhiXi (ZX) and HS. Multivariate statistical analysis suggested that there was great heterogeneity in the sources of these heavy metals in the hilly area of southern China. Therefore, specific measures, such as controls on point source pollution control and tailings, should be taken for maintaining drinking water safety and aquatic ecosystem health.

The '333' integrated strategy for effective pollution control and its application to the heavily polluted Jialu River in north China.

In this study, an integrated approach named the '333' strategy was applied to pollution control in the Jialu River, in northern China, which is heavily burdened with anthropogenic pollution. Due to a deficiency of the natural ecological inflow, the Jialu River receives predominantly industrial and municipal effluent. The '333' strategy is composed of three steps of pollution control including industrial point-source pollution control, advanced treatment of municipal wastewater, and ecological restoration; three increased stringency emission standards; and three stages of reclamation. Phase 1 of the '333' strategy focuses on industrial point-source pollution control; phase 2 aims to harness municipal wastewater and minimize sewage effluents using novel techniques for advanced water purification; phase 3 of the '333' strategy focuses on the further purification of effluents flowing into Jialu River with the employment of an engineering-based ecological restoration project. The application of the '333' strategy resulted in the development of novel techniques for water purification including modified magnetic resins (NDMP resin), a two-stage internal circulation anaerobic reactor (IC reactor) and an ecological restoration system. The results indicate that water quality in the river was significantly improved, with increased concentrations of dissolved oxygen (DO), as well as reduction of COD by 42.8% and NH3-N by 61.4%. In addition, it was observed that the total population of phytoplankton in treated river water notably increased from only one prior to restoration to 8 following restoration. This system also provides a tool for pollution control of other similar industrial and anthropogenic source polluted rivers.

Influence of Land Use and Point Source Pollution on Water Quality in a Developed Region: A Case Study in Shunde, China.

To design and implement policy to manage water quality, it is important to investigate land use and possible sources of pollution. In this study, using Pearson regression analysis, redundancy analysis and multiple regression analysis, we assess the influence of land use and point sources on water quality in the river system in Shunde district in 2000 and 2010. The results show that water quality was related positively with water surface but negatively with impervious and urban greening area. Additionally, water quality was related negatively to point source emissions of chemical oxygen demand (COD) and ammonium-nitrogen (NH4-N). The total explanatory power of spatial variation of water quality was improved from 43.4% to 60.0% in 2000 and from 31.3% to 57.8% in 2010, respectively, when the influence of point sources was added into redundancy analysis between water quality and land use. Thus, both land use management and point source pollution control should be considered for improving river water quality.

Water quality assessment and source identification of water pollution in the Banchengzi reservoir, Beijing, China

Water quality in the Banchengzi reservoir in Beijing has been deteriorating year by year, and it was embodied by increasing concentrations of COD and stable but high levels of total nitrogen. In order to identify the causes and to formulate a strategy for pollution prevention and control, we examined the temporal and spatial variations of water pollution and carried out source identification studies. Routine monthly monitoring data for seven water quality and six hydro-meteorological variables of the Banchengzi reservoir from 2007 to 2012 were analyzed by statistical techniques, including correlation analysis and principle component analysis. In addition, water samples at six different sites in the reservoir were collected and analyzed to investigate the spatial variation of water quality and to further identify the water pollution sources by UV–vis spectroscopy, three-dimensional excitation-emission matrix spectroscopy, and nitrogen stable isotope (δ15N) analysis. The results revealed that dissolved organic matter and nitrogen were the main pollutants and were principally derived from anthropogenic point source pollution in the upper areas, which included domestic sewage and livestock farming. We speculated that the biodegradable organic pollutants from sewage were degraded to form soluble microbial products (SMP) by aerobic microorganisms and that nitrogen pollutants were mostly transformed to nitrate by nitrification. These SMP, nitrate, and other refractory pollutants were carried by the upper stream flowing into the Banchengzi reservoir, where it accumulated. Effective control of point source pollution and upper river ecological restoration should be done to improve the water quality and protect the reservoir.

Analysis on current situation of water pollution and pollutant sources in Ningxia Yellow River irrigation region

随着点源污染的逐步控制, 以农业生产为核心的农业非点源污染正在成为影响水体质量的主要因子。宁夏引黄灌区是我国商品粮生产基地之一, 农业生产较为发达, 农业的高投入对当地水体环境造成不良影响。本文分析了2002~2007年黄河宁夏段监测断面和引黄灌区典型排水沟的水质情况, 发现黄河宁夏段水质受农田退水、工业废水和生活污水影响较大, 境内沿程断面水质污染逐渐加剧, 水质出境断面比入境断面平均降低1个等级, 说明黄河流经宁夏后水质受到一定程度的污染。宁夏引黄灌区水体主要污染物是挥发酚、NH₄⁺-N、COD_Mn和BOD₅, 2002~2007年几种主要污染物浓度总体呈下降趋势, 综合污染指数也呈总体下降趋势, 但污染形势仍然严重。2007年宁夏引黄灌区主要排水沟水质为劣Ⅴ类污染水质, 断面超标率100%, 主要污染物为NH₄⁺-N、COD_Cr、BOD₅。针对黄河宁夏段水体污染状况, 对宁夏引黄灌区水体农业非点源污染源进行解析, 结果显示, TN、NH₄⁺-N污染主要来自种植业, 其次是养殖业和黄河取水; TP污染主要来自于种植业与养殖业, COD主要来自养殖业。农田退水携带的大量污染物是导致灌区水体恶化的重要因素之一。

Preliminary identification of watershed management strategies for the Houjing river in Taiwan

The Houjing River watershed is one of the three major river watersheds in the Kaohsiung City, Taiwan. Based on the recent water quality analysis, the Houjing River is heavily polluted. Both point and non-point source (NPS) pollutants are the major causes of the poor water quality in the Houjing River. Investigation results demonstrate that the main point pollution sources included municipal, agricultural, and industrial wastewaters. In this study, land use identification in the Houjing River watershed was performed by integrating the skills of geographic information system (GIS) and global positioning system (GPS). Results show that the major land-use patterns in the upper catchment of the Houjing River watershed were farmlands, and land-use patterns in the mid to lower catchment were residential and industrial areas. An integrated watershed management model (IWMM) and Enhanced Stream Water Quality Model (QUAL2K) were applied for the hydrology and water quality modeling, watershed management, and carrying capacity calculation. Modeling results show that the calculated NH₃-N carrying capacity of the Houjing River was only 31 kg/day. Thus, more than 10,518 kg/day of NH₃-N needs to be reduced to meet the proposed water quality standard (0.3 mg/L). To improve the river water quality, the following remedial strategies have been developed to minimize the impacts of NPS and point source pollution on the river water quality: (1) application of BMPs [e.g. source (fertilizer) reduction, construction of grassy buffer zone, and land use management] for NPS pollution control; (2) application of river management scenarios (e.g. construction of the intercepting and sewer systems) for point source pollution control; (3) institutional control (enforcement of the industrial wastewater discharge standards), and (4) application of on-site wastewater treatment systems for the polishment of treated wastewater for water reuse.

Application of Media Manufactural by Waste Plastic to Stormwater Treatment in Urban Drainage System

While more attention has been paid in recent years to urban point source pollution control, no considerable measures have been taken to control urban non-point source pollution. Contaminants from non-point sources deposited on urban impermeable surfaces such as road and highway are easily released to the public waters by rainfall, leading to the deterioration in water quality in urban area. Experiments were performed using a reactor and real rainwater runoff obtained from road surfaces at various pollutant loading and rainfall intensity to determine the criteria for the first flush rainwater and to evaluate the applicability of the reactor for treating road runoff. The results at different rainfall intensities show that the medium PPB is superior to the other media for water permeability. PPB was not blocked at 10 mm/hr rainfall, and its permeability was stable. On the other hand, PVS and PPF resulted in a substantial overflow ratio even at 1 mm/hr rainfall intensity. Comparison of treatment efficiencies for suspended solids showed that all media showed similar removal efficiency ranging from 91% to 95%. However, PPB seems to be better than the other media considering its higher water permeability. PPB and PPF, both hydrophobic, yielded over 76% of heavy metal removal. But the hydrophilic media PVS showed much smaller removal efficiency ranging from 26% to 47%. The treatment efficiencies over PAHs (Poly Aromatic Hydrocarbons) showed the similar removal efficiency ranging from 66% to 97% for all three media. In this study a reactor using filter media was investigated to reduce the level of contamination in urban road runoff.

Pollution loads in urban runoff and sanitary wastewater

While more attention has been paid in recent years to urban point source pollution control through the establishment of wastewater treatment plants in many developing countries, no considerable planning nor any serious measures have been taken to control urban non-point source pollution (urban stormwater runoff). The present study is a screening analysis to investigate the pollution loads in urban runoff compared to point source loads as a first prerequisite for planning and management of receiving water quality. To compare pollutant loads from point and non-point urban sources, the pollutant load is expressed as the weight of pollutant per hectare area per year (kg/ha·year). Unit loads were estimated in stormwater runoff, raw sanitary wastewater and secondary treatment effluents in Isfahan, Iran. Results indicate that the annual pollution load in urban runoff is lower than the annual pollution load in sanitary wastewater in areas with low precipitation but it is higher in areas with high precipitation. Two options, namely, advanced treatment (in lieu of secondary treatment) of sanitary wastewater and urban runoff quality control systems (such as detention ponds) were investigated as controlling systems for pollution discharges into receiving waters. The results revealed that for Isfahan, as a low precipitation urban area, advanced treatment is a more suitable option, but for high precipitation urban areas, urban surface runoff quality control installations were more effective for suspended solids and oxygen-demanding matter controls, and that advanced treatment is the more effective option for nutrient control.

An object-oriented tool for the control of point-source pollution in river systems

Computer-aided management of surface-water quality has been a field of continuous progress in the last decades. Object-orientation offers the potential for the development of efficient software tools, capable of dealing with the complexity of water resources and their policy making. In the present work an object-oriented approach has been developed for the analysis of point-source pollution control in river basins. The physical entities of the river basin and the conceptual entities of its water-quality simulation and control have been represented through objects. With the appropriate distribution of responsibilities among these objects and the specification of their collaborations, the assessment and simulation of river water quality can be performed. Alternative strategies of point-source pollution control can be also evaluated, and an optimised control scheme can be suggested. The above analysis has been implemented in the design and development of an easily extended and flexible software tool, using the object-oriented language Smalltalk Express. The tool has been successfully validated through the studies of the South Nation River Catchment in Canada and the Upper Mersey River Catchment in the United Kingdom. In this work the architecture of the software tool is outlined and the employed mathematical analysis along with the results of the case studies are presented.

A state-contingent production approach to principal-agent problems with an application to point-source pollution control

Two basic representations of principal-agent relationships, the `state-space' and `parameterized distribution' formulations, have emerged. Although the state-space formulation appears more natural, analytical studies using this formulation have had limited success. This paper develops a state-space formulation of the moral-hazard problem using a general representation of production under uncertainty. A closed-form solution for the agency-cost problem is derived. Comparative-static results are deduced. Next we solve the principal's problem of selecting the optimal output given the agency-cost function. The analysis is applied to the problem of point-source pollution control.

ANSWERS-2000: Runoff and Sediment Transport Model

A non–point source pollution management model, ANSWERS-2000, was developed to simulate long-term average annual runoff and sediment yield from agricultural watersheds. The model is based on the event-based ANSWERS model and is intended for use without calibration. The physically based Green-Ampt infiltration equation was incorporated into ANSWERS-2000 to improve estimates of infiltration. An evapotranspiration submodel was added to permit long-term, continuous simulation. The model was validated without calibration using data from the field-sized P2 and P4 watersheds in Watkinsville, Ga. Additional validation with limited calibration was done on the Owl Run watershed in Virginia. Model predictions of cumulative sediment yield were within 12% and 68% of observed values. Predicted cumulative runoff volumes ranged from 3% to 35% of observed values. Predictions of sediment yield and runoff volume for individual storms were less accurate, but generally within 200% of observed values. In a practical application, the use of the model in agricultural non–point-source pollution control planning was demonstrated.