Watershed Pollution Research Articles

The Relationship between Land Use and Vulnerability to Nitrogen and Phosphorus Pollution in an Urban Watershed.

Characterization of the vulnerability of water bodies to pollution from natural and anthropogenic sources requires understanding the relationship between land use and water quality. This study aims (i) to explore the influence of upstream land use on annual stream water concentrations and loads of total nitrogen (TN) and phosphorus (TP) and (ii) to characterize the vulnerability of water bodies to TN and TP pollution as a function of land use under varying climatic conditions. Multiple linear regression models were used across 23 stream locations within the Jordan Lake watershed in North Carolina between 1992 and 2012 to explore land use-water quality relationships. The percentage of urban land use and wastewater treatment plant capacity were the most important factors with strong ( 0.7) and significant ( < 0.01) positive correlations with annual TN and TP concentrations and loads. Percent agricultural land was negatively correlated with TN in 18 out of 21 yr of the study period. Using analysis of covariance, significant ( 0.01) differences were determined between models developed for urban land use with TN and TP loads based on annual precipitation. Using concentrations instead of loads resulted in a nonsignificant difference between models for average and wet years. Finally, a procedure was developed to characterize the vulnerability to TN and TP pollution, computed as the probability of exceeding the nutrient standard limits. Results indicated that the vulnerability to TN and TP was controlled primarily by urban land use, with higher values in dry years than normal and wet years.

Legacy organochlorine pollutants in glacial watersheds: a review.

Northern Hemisphere alpine glaciers have been identified as a point of concentration and reemergence of legacy organochlorine pollutants (OCPs). In this review, we compile a selection of published literature combining long-range, global atmospheric transport and distribution-based compartmental environmental flux models, as well as data from glacial meltwater, ice core, crevasse and proglacial lake sediment studies. Regional studies of ice and meltwater in alpine glaciers of the northern latitudes show similarities in sample deposition profiles and concentration due to chemical atmospheric residence time, precipitation type and glacier flow rates. In glaciated locations near areas of extensive OCPs use, such as the Swiss and Italian Alps, glacier sample concentrations are higher, while in areas more distant from use, including Arctic nations, OCPs concentrations in glaciers are significantly lower. Our review identifies alpine glaciers co-located with regions characterized by OCPs use as a significant organochlorine pollutant distribution source, secondary in timing and location to direct deposition, with subsequent bioaccumulation and potential human risk impacts.

Water quality modeling for typical rural watershed based on the WASP model in Mountain Mao Region, upper Taihu Basin

池塘、河渠、水库是乡村流域水环境的重要组成. 基于WASP模型，综合运用现场调查、GIS空间分析、污染负荷估算等方法，构建茅山地区李塔陈庄乡村流域的水质模拟模型. 结果表明，主要水质指标的污染程度从高至低依次为总氮（TN）、总磷（TP）和高锰酸盐指数、氨氮. TN全年在不同水体中达到劣Ⅴ类的比例在52%~100%，而池塘、河渠的污染程度较为接近. 夏、冬季，超过TP劣Ⅴ类限值的河渠占2%~6%，池塘占8%~14%，而流域中部乡村周边的池塘明显更为严重. 负荷输入是模型主要不确定性因素，细化种植模式能够提高总体模拟效果，而禽畜散养与农村生活造成的污染则分别对池塘、河渠的水质影响更为明显. 本研究建立了乡村流域多种水体在面源污染影响下的水质联系，能够为乡村水环境治理提供决策参考.;Ponds, rivers and reservoirs are the basic elements of water environment in a rural watershed, especially in the humid regions of Southeastern China. The water quality model for Lita-chenzhuang rural watershed in Mountain Mao Region is developed based on the WASP model. It is a combination among field investigation, GIS spatial analysis, pollution loads estimation and so on. The result shows that the order of contamination level of the main water quality indicators are total nitrogen (TN), total phosphorus (TP), permanganate index, and ammonia nitrogen, respectively. For TN concentrations of the year, 52%-100% of different water bodies are worse than GradeⅤ of Environmental Quality Standards for Surface Water of China(GB 3838-2002), while the ponds are relatively close to the rivers on the contamination. During summer and winter, 2%-6% of rivers and 8%-14% of ponds have exceeded the upper bound of GradeⅤ in TP concentrations.Ponds in the center of the watershed and near the village are obviously more contaminated. The pollution loads are the main uncertainty factor of the water quality model. So the refinement on planting patterns could improve the simulation results on the whole. The pollutants from unfenced livestock and poultry have more effect on the ponds, while the water quality of the rivers is more vulnerable to sewage and garbage. This study establishes the links of water quality in different water bodies, which are affected by non-point source pollution in a typical rural watershed. It is also useful to formulate mitigation measures on rural water environment.

Spatial patterns and origins of heavy metals in Sheyang River catchment in Jiangsu, China based on geographically weighted regression.

Multivariate statistical analyses combined with geographically weighted regression (GWR) were used to identify spatial variations of heavy metals in sediments and to examine relationships between metal pollution and land use practices in watersheds, including urban land, agriculture land, forest and water bodies. Seven metals (Cu, Zn, Pb, Cr, Ni, Mn and Fe) of sediments were measured at 31 sampling sites in Sheyang River. Most metals were under a certain degree enrichment based on the enrichment factors. Cluster analysis grouped all sites into four statistically significant cluster, severely contaminated areas were concentrated in areas with intensive human activities. Correlation analysis and PCA indicated Cu, Zn and Pb were derived from anthropogenic activities, while the sources of Cr and Ni were complicated. However, Fe and Mn originated from natural sources. According to results of GWR, there are stronger association between metal pollution with urban land than agricultural land and forest. Moreover, the relationships between land use and metal concentration were affected by the urbanization level of watersheds. Agricultural land had a weak associated with heavy metal pollution and the relationships might be stronger in less-urbanized. This study provided useful information for the assessment and management of heavy metal hazards in studied area.

Surface drainage nitrate loading estimate from agriculture fields and its relationship with landscape metrics in Tajan watershed

Pasture, forest, and farmland are the dominant land covers in the Tajan River watershed and this landscape status has a direct connection with nitrate pollution. Understanding the correlations between landscape variables and nitrate pollutant is a priority in order to assess pollutants loading and predicting the impact on surface water quality. The soil and water assessment tool was used to simulate nitrate loads in different land cover types in different years. The landscape pattern was calculated by FRAGSTATS. The contributing share of each land use/land cover shows nitrate pollutant produced by grassland (5.7%) and forest (29%) are less than those produced by agricultural land (64.2%). Agricultural land was identified as the main source of nitrate pollution. Paddy fields and orchards had the most intensive soluble nitrate loss especially in spring and summer. Statistical analysis indicated that nitrate was positively associated with patch density, edge density, patch number, total edge, effective mesh size, largest patch index, and landscape shape index (p ≤ 0.01). We then analyzed how nitrate was related to landscape attributes in six different sites. Also the regression analysis results suggested that landscape metrics could account for more than 94% of the variance of nitrate in the whole catchment. The regression models confirmed the great importance of the agriculture metrics and forest metric in predicting nitrate in watershed. Defining the generation and extent of pollution in this particular watershed which discharges into the Caspian Sea can constitute an important step toward protecting this ecosystem.

How much conservation is enough? Defining implementation goals for healthy fish communities in agricultural rivers

Abstract “How much conservation is enough?” is one of the most important and difficult questions to answer. In this work, we demonstrate an approach to specifically answer this question for conservation strategies designed to address nonpoint source pollution in agriculturally-dominated watersheds. We developed empirical models relating conservation investments and actions to measures of stream water quality and fish community health. Our results are consistent with other studies that demonstrate a need for extensive implementation of conservation practices in agricultural landscapes to see measurable improvements in ecological conditions. Our results also demonstrate the influence spatial grain can have on answering “how much conservation is enough?” Our coarse-grained analyses suggest that water quality in at the outlets of four watersheds could be improved to the point that water quality was no longer limiting the fish community with only about 18% of the agricultural lands treated with conservation practices and incentive payments totaling $7.7M. Yet, finer-grained subbasin analyses predict fish communities would still be limited in many tributaries of these watersheds even with ~ 50% of lands treated and incentive payments totaling ~$44M. Consequently, coarsegrained analyses could significantly underestimate scope of the solution needed to address these impacts to stream ecosystems. Finding balanced solutions to address agricultural nonpoint source pollution throughout the Great Lakes will require unprecedented collaboration from local to regional scales. Herein, we provide examples of how this work is supporting collaborative efforts to establish realistic ecological goals and associated performance measures and strategic implementation of practices throughout the Saginaw Bay drainage.

Local Stressors, Resilience, and Shifting Baselines on Coral Reefs.

Understanding how and why coral reefs have changed over the last twenty to thirty years is crucial for sustaining coral-reef resilience. We used a historical baseline from Kosrae, a typical small island in Micronesia, to examine changes in fish and coral assemblages since 1986. We found that natural gradients in the spatial distribution of fish and coral assemblages have become amplified, as island geography is now a stronger determinant of species abundance patterns, and habitat forming Acropora corals and large-bodied fishes that were once common on the leeward side of the island have become scarce. A proxy for fishing access best predicted the relative change in fish assemblage condition over time, and in turn, declining fish condition was the only factor correlated with declining coral condition, suggesting overfishing may have reduced ecosystem resilience. Additionally, a proxy for watershed pollution predicted modern coral assemblage condition, suggesting pollution is also reducing resilience in densely populated areas. Altogether, it appears that unsustainable fishing reduced ecosystem resilience, as fish composition has shifted to smaller species in lower trophic levels, driven by losses of large predators and herbivores. While prior literature and anecdotal reports indicate that major disturbance events have been rare in Kosrae, small localized disturbances coupled with reduced resilience may have slowly degraded reef condition through time. Improving coral-reef resilience in the face of climate change will therefore require improved understanding and management of growing artisanal fishing pressure and watershed pollution.

Nutrient Cycling in Grassed Roadside Ditches and Lawns in a Suburban Watershed.

Roadside ditches are ubiquitous in developed landscapes. They are designed to route water from roads for safety, with little consideration of water quality or biogeochemical implications in ditch design and minimal data on environmental impacts. We hypothesize that periodic saturation and nutrient influxes may make roadside ditches hotspots for nitrogen (N) removal via denitrification as well as biological production of the greenhouse gases (GHGs) nitrous oxide (NO), methane (CH), and carbon dioxide (CO). Research sites included 12 grassed ditches and adjacent lawns with varying fertilization in a suburban watershed in central New York, where lawns represented a reference with similar soils as ditches but differing hydrology. We measured potential denitrification using the denitrification enzyme assay in fall 2014 and GHG fluxes using in situ static chambers between summer 2014 and 2015, including sample events after storms. Potential denitrification in ditches was significantly higher than in lawns, and rates were comparable to those in stream riparian areas, features traditionally viewed as denitrification hotspots. Ditches had higher rates of CH emissions, particularly sites that were wettest. Lawns were hotspots for NO and CO respiratory emissions, which were driven by nutrient availability and fertilizer application. Extrapolating up to the watershed, ditches have the potential to remove substantial N loads via denitrification if managed optimally. Ditch GHG emissions extrapolated across the watershed were minimal given their much smaller area compared with lawns, which were the greater contributor of GHGs. These findings suggest that roadside ditches may offer new management opportunities for mitigating nonpoint source N pollution in residential watersheds.

An Integrated Approach for Targeting Critical Source Areas to Control Nonpoint Source Pollution in Watersheds

This study presents an integrated approach for targeting critical source areas (CSAs) to control nonpoint source pollution in watersheds. CSAs are the intersections between hydrologically sensitive areas (HSAs) and high pollution producing areas of watersheds. HSAs are the areas with high hydrological sensitivity and potential for generating runoff. They were based on a soil topographic index in consistence of a saturation excess runoff process. High pollution producing areas are the areas that have a high potential for generating pollutants. Such areas were based on simulated pollution loads to streams by the Soil and Water Assessment Tool. The integrated approach is applied to the Neshanic River watershed, a suburban watershed with mixed land uses in New Jersey in the U.S. Results show that several land uses result in water pollution: agricultural land causes sediment, nitrogen and phosphorus pollution; wetlands cause sediment and phosphorus pollution; and urban lands cause nitrogen and phosphorus pollution. The primary CSAs are agricultural lands for all three pollutants, urban lands for nitrogen and phosphorus, and wetlands for sediment and phosphorus. Some pollution producing areas were not classified into CSAs because they are not located in HSAs and the pollutants generated in those areas are less likely to be transported by runoff into streams. The integrated approach identifies CSAs at a very fine scale, which is useful for targeting the implementation of best management practices for water quality improvement, and can be applied broadly in different watersheds to improve the economic efficiency of controlling nonpoint source pollution.

Perspectives on policy framework for trans-boundary water quality management in China

ABSTRACTIn river basins that cross jurisdictional boundaries, water quality degradation has become a crucial problem and results in intensive competition among water users, especially in developing countries. Under this situation, implementing water quality management and control across jurisdictional boundaries can strengthen watershed pollution controls, and prevent pollution from being passed on and promote active pollution control within the related jurisdictional regions. This study examined the limitations of the current trans-boundary water quality management system in China and reviewed the planning and implementation of two pilot integrated trans-boundary water management systems established in the Jiangsu and Zhejiang provinces. Based on our findings, we proposed a new policy framework for trans-boundary water quality management. As a first step toward integrated watershed management in China, this policy framework can help assess the actual water pollution status of various regions and serve as a basis for an integrated watershed management system. The framework can be easily applied in other countries with trans-boundary water pollution issues, particularly in the context of developing countries.

Finite Element Simulation of Total Nitrogen Transport in Riparian Buffer in an Agricultural Watershed

Riparian buffers can influence water quality in downstream lakes or rivers by buffering non-point source pollution in upstream agricultural fields. With increasing nitrogen (N) pollution in small agricultural watersheds, a major function of riparian buffers is to retain N in the soil. A series of field experiments were conducted to monitor pollutant transport in riparian buffers of small watersheds, while numerical model-based analysis is scarce. In this study, we set up a field experiment to monitor the retention rates of total N in different widths of buffer strips and used a finite element model (HYDRUS 2D/3D) to simulate the total N transport in the riparian buffer of an agricultural non-point source polluted area in the Liaohe River basin. The field experiment retention rates for total N were 19.4%, 26.6%, 29.5%, and 42.9% in 1,3,4, and 6m-wide buffer strips, respectively. Throughout the simulation period, the concentration of total N of the 1mwide buffer strip reached a maximum of 1.27 mg/cm3 at 30 min, decreasing before leveling off. The concentration of total N about the 3mwide buffer strip consistently increased, with a maximum of 1.05 mg/cm3 observed at 60 min. Under rainfall infiltration, the buffer strips of different widths showed a retention effect on total N transport, and the optimum effect was simulated in the 6mwide buffer strip. A comparison between measured and simulated data revealed that finite element simulation could simulate N transport in the soil of riparian buffer strips.

Spatio-temporal variation of erosion-type non-point source pollution in a small watershed of hilly and gully region, Chinese Loess Plateau.

Loss of nitrogen and phosphorus in the hilly and gully region of Chinese Loess Plateau not only decreases the utilization rate of fertilizer but also is a potential threat to aquatic environments. In order to explore the process of erosion-type non-point source (NPS) pollution in Majiagou watershed of Loess Plateau, a distributed, dynamic, and integrated NPS pollution model was established to investigate impacts of returning farmland on erosion-type NPS pollution load from 1995 to 2012. Results indicate that (1) the integrated model proposed in this study was verified to be reasonable; the general methodology is universal and can be applicable to the hilly and gully region, Loess Plateau; (2) the erosion-type NPS total nitrogen (TN) and total phosphorus (TP) load showed an overall decreasing trend; the average nitrogen and phosphorus load modulus in the last four years (2009-2012) were 1.23 and 1.63t/km(2) · a, respectively, which were both decreased by about 35.4% compared with the initial treatment period (1995-1998); and (3) The spatial variations of NPS pollution are closely related to spatial characteristics of rainfall, topography, and soil and land use types; the peak regions of TN and TP loss mainly occurred along the main river banks of the Yanhe River watershed from northeast to southeast, and gradually decreased with the increase of distance to the left and right river banks, respectively. Results may provide scientific basis for the watershed-scale NPS pollution control of the Loess Plateau.

Hydrogeochemistry of arsenic pollution in watersheds influenced by gold mining activities in Paracatu (Minas Gerais State, Brazil)

The aim of this study is to evaluate total arsenic (As) concentrations in drinking water (main pathway of human exposure) and its hydrogeochemical controls in the "Morro do Ouro" gold mine region, which is the largest gold mine in Brazil, characterized by gold-arsenopyrite association. Arsenic concentration was generally below the detection limit (LOD < 0.5μgL(-1)). Thus, water ingestion may not be a significant exposure pathway to local population. Low groundwater As concentrations (<1μgL(-1)) are likely due to ore body structural setting, which plunges from 10° to >20°, being readily covered by thick phyllites that are poor in As some hundreds of meters away from the mine. Thirty-five percent of As levels in superficial waters (<0.5 to 40μgL(-1)) were >10μgL(-1), which is the maximum permissible value for human ingestion. The highest concentrations were found nearby mine facilities and old artisanal mining areas surrounding the mine, decreasing downstream. Undisturbed watersheds showed As concentrations close to LOD. Hydrogeochemical data stress the sorption (adsorption and co-precipitation) of As role, mainly by Fe oxyhydroxides, as a geochemical filter that retains As, attenuating its concentration in both superficial and groundwater. Such minerals are abundant in the region oxisols, sediments, and phyllites and may form stable mineral complexes with As under the pH (mostly neutral) and Eh (reduced environment) conditions found in the field. It has been demonstrated that As(III) (more toxic) and As(V) co-exist in the analyzed waters and that As(V) predominates in superficial water.

How To Identify And Prioritize Watershed Pollution Sources? ------ Case Studies of Transform Water Quality Data into Decision Making Tool

How To Identify And Prioritize Watershed Pollution Sources? ------ Case Studies of Transform Water Quality Data into Decision Making Tool

Distribution and contamination of metals in the soil of Guandu Watershed

Coastal areas provide important benefits to humans in terms of food resources and ecosystem services. At the same time, human activities can have significant negative impacts on ecosystem health. Thus, control of watershed pollution is both necessary and essential in order to reduce and systematically eliminate the detrimental consequences that are evident in marine and estuarine ecosystems. The present study investigated the distribution of metals at the Guandu Watershed. Five sampling sites were selected for the soil analysis. Samples were collected from February 2013 to December 2014 and analysed for concentrations of As, Cd, Zn, Cu, Pb, Cr, Ni, and Co, using ICP. For control, some samples were used in uncontaminated areas outside the direct effect of chemical industries. The data indicate the presence of metals at the research sites. While the levels of contamination are still slightly below the peak concentrations established by Brazilian legislation, they are approaching levels of concern, particularly with regard to As, Cd, Pb and Cr. The results indicate that the use of water from the Guandu Watershed for recreational purposes and fishing is harmful to both human health and the environment.

Nonpoint Source Pollution.

The article presents a comprehensive review of research advancing in 2014 on nonpoint source pollution (NPS). The topics presented relate to nonpoint source pollution (NPS) within agricultural and urban areas. NPS pollution from agricultural areas is the main focus in this review. Management of NPS in agricultural, urban and rural areas is presented. Modeling of NPS pollution in different watersheds with various modeling tools is reviewed.

Prevalence of and Relationship between Two Human-Associated DNA Biomarkers for Bacteroidales in an Urban Watershed.

Human-associated fecal biomarkers offer potent tools for the detection and control of human fecal pollution in watersheds. In some cases, the probability of false-negative findings may call for using a less specific biomarker that is present in higher quantities as long as it can be related to the more specific indicator. The objective of this study is to investigate the relationship between two previously published human-associated biomarkers for Bacteroidales bacteria in an urban watershed influenced by human fecal pollution and to determine if the less specific marker may be used to identify the locations of broken or leaking sewer lines. Samples were collected from 19 stream locations on 10 dates. Sample DNA was extracted and qPCR analysis was conducted for the HuBac and qHF183 biomarkers. The HuBac biomarker was detected more frequently than the qHF183 biomarker and in greater quantities when both were detected. A strong linear relationship ( = 0.91) between the two markers was observed in 219 samples taken from both the watershed and inlet sewage. The relationship between the two biomarkers showed less variance at higher concentrations. However, even when the inlet sewage samples were excluded from the dataset, a clear linear relationship remained ( = 0.74). The results indicate that use of a less specific, but more sensitive, biomarker may provide greater utility when the prevention of false negatives is necessary and the primary fecal source is known, as in spatial distribution studies of human fecal pollution in an urban watershed.

A Methodological Approach for Spatiotemporally Analyzing Water-Polluting Effluents in Agricultural Landscapes Using Partial Triadic Analysis.

Multivariate techniques for two-dimensional data matrices are normally used in water quality studies. However, if the temporal dimension is included in the analysis, other statistical techniques are recommended. In this study, partial triadic analysis was used to investigate the spatial and temporal variability in water quality variables sampled in a northeastern Spain river basin. The results highlight the spatiality of the physical and chemical properties of water at different sites along a river over 1 yr. Partial triadic analysis allowed us to clearly identify the presence of a stable spatial structure that was common to all sampling dates across the entire catchment. Variables such as electrical conductivity and Na and Cl ions were associated with agricultural sources, whereas total dissolved nitrogen, NH-N concentrations, and NO-N concentrations were linked to polluted urban sites; differences were observed between irrigated and nonirrigated periods. The concentration of NO-N was associated with both agricultural and urban land uses. Variables associated with urban and agricultural pollution sources were highly influenced by the seasonality of different activities conducted in the study area. In analyzing the impact of land use and fertilization management on water runoff and effluents, powerful statistical tools that can properly identify the causes of pollution in watersheds are important. Partial triadic analysis can efficiently summarize site-specific water chemistry patterns in an applied setting for land- and water-monitoring schemes at the landscape level. The method is recommended for land-use decision-making processes to reduce harmful environmental effects and promote sustainable watershed management.

Fecal Contamination in the Surface Waters of a Rural- and an Urban-Source Watershed.

Surface waters are commonly used as source water for drinking water and irrigation. Knowledge of sources of fecal pollution in source watersheds benefits the design of effective source water protection plans. This study analyzed the relationships between enteric pathogens ( O157:H7, spp., and spp. [, and ]), water quality (turbidity, temperature, and ), and human and ruminant-cow and mitochondrial DNA (mtDNA)-based fecal source tracking (FST) markers in two source watersheds. Water samples ( = 329) were collected at 10 sites (five in each watershed) over 18 mo. The human marker (HF183) occurred in 9 to 10% of the water samples at nine sampling sites; while a forested site in the urban watershed tested negative. Ruminant-cow markers (BacR and CowM2) only appeared in the rural watershed (6%). The mtDNA markers (HcytB and AcytB) showed the same pattern but were less sensitive due to lower fecal concentrations. Higher prevalences ( < 0.05) of spp. (41 vs. 16% for the rural and urban watershed, respectively) and O157:H7 (12 vs. 3%) were observed in the rural watershed, while spp. levels were comparable (23-28%). Densities of ≥100 colony-forming units (CFU) 100 mL increased the odds ( < 0.05) of detecting the enteric bacterial pathogens. The water turbidity levels (nephelometric turbidity units [NTU] ≥ 1.0) similarly predicted ( < 0.05) pathogen presence. Storm events increased ( < 0.01) pathogen and fecal marker concentrations in the waterways. The employment of multiple FST methods suggested failing onsite wastewater systems contribute to human fecal pollution in both watersheds.

Point and non-point source nutrient loading simulation for the Takasaki River Basin, Chiba–Japan

Urbanization, agriculture, fertilization, livestock farming and unprecedented precipitations are presumed to cause augmented loadings of nitrogen (N) and phosphorus (P) to rivers and downstream reservoirs. At present, point source (PS) pollution in watersheds can easily be controlled, and it has been well-managed due to growing awareness and strict low enforcements. However, the control of pollutants from non-point sources (NPS) is still challenging and NPS have been identified as the main cause of water pollution and eutrophication in watersheds at present. Limitations in technical, human and financial resources impede efficient monitoring of those influents at watershed scale. At this end, process-based modelling approaches play an important role in analysis of nutrient loading effects quantitatively and qualitatively. Process-based water and energy processes (WEP) hydrological model with its updated version to couple nutrient loading through the implementation of N and P circulation processes was studied in this paper highlighting the application of the model to the Takasaki River, a tributary to the Inba-numa Lake basin, Chiba prefecture, Japan to understand the impacts of PS and NPS to the river water quality.