Fate and transport of pollutants through a municipal solid waste landfill leachate in Sri Lanka

This study focuses on the characterization of leachate generated from Gohagoda dumpsite in Kandy, Sri Lanka, assessment of its spatial and temporal variations, and identification of subsurface canals and perched water bodies in the wetland system affected by the leachate flow. Leachate samples were collected monthly throughout dry and rainy seasons from different points of the leachate drainage channel over a period of 1 year and they were tested for quality parameters: pH, temperature, electrical conductivity, total dissolved soils, alkalinity, hardness, total solids, volatile solids, total suspended solids, volatile suspended solids, biochemical oxygen demand (BOD₅), chemical oxygen demand, nitrate-nitrogen, nitrite-nitrogen, phosphates, ammonium-nitrogen, chloride, dissolved organic carbon, total organic carbon and heavy metals. Sequential soil extraction procedures were performed for the characterization of leachate-affected local soil. A geophysical survey using direct current resistivity technique was conducted at locations downstream of the dumpsite. Leachate characteristics indicated that the leachate is in the methanogenic phase and the results strongly suggest that the leachate may be polluting the river where the leachate is discharged directly. Leachate exceeds the allowable limits of Sri Lankan wastewater discharge standards for many of the parameters. Significant difference (P < 0.05) was observed for most of organic and inorganic parameters among all sampling locations. Many parameters showed a negative correlation with pH. The affected soils showed high heavy metal concentrations. Resistivity study confirmed a confined leachate flow at the near surface with few subsurface canals. However, no separate subsurface plume movement was observed. The results of this research can effectively be used for the establishment of an efficient and effective treatment method for the Gohagoda landfill leachate.     

Water quality index and fractal dimension analysis of water parameters

Statistical analysis of water quality parameters were analyzed at Harike Lake on the confluence of Beas and Sutlej rivers of Punjab (India). Mean, median, mode, standard deviation, kurtosis, skewness, coefficient of variation, regression lines, correlation coefficient, Hurst exponent, fractal dimension and predictability index were estimated for each water parameter. Monthly variation of water quality index using month-wise and parameter-wise value of quality rating and actual value present in water sample was calculated and compared with World Health Organization/Environmental Protection Agency standard value of these parameters. It was observed that Brownian time series behavior exists of potential of hydrogen with total dissolved solids, hardness, alkalinity, sulfate, chloride and conductance parameters; biochemical oxygen demand with total dissolved solids, hardness, alkalinity, sulfate, chloride, conductance and calcium parameters; dissolved oxygen with total dissolved solids, hardness, alkalinity, sulfate, chloride, conductance and calcium parameters; ferrous with total dissolved solids, hardness, alkalinity, sulfate, conductance and calcium parameters; chromium with total dissolved solids, hardness, alkalinity, sulfate, chloride, conductance and zinc parameters; zinc with total dissolved solids, hardness, sulfate, chloride, conductance and calcium parameters; fluoride with total dissolved solids, hardness, alkalinity, sulfate, chloride and conductance parameters; nitrate with total dissolved solids, sulfate and conductance parameters; nitrite with potential of hydrogen, total dissolved solids, hardness, alkalinity, sulfate, chloride, conductance and calcium parameters. Also, using water quality index, it was observed that water of the lake was severely contaminated and became unfit for drinking and industrial use.     

Heavy metal assessment and water quality values in urban stream and rain water

Water quality monitoring in developing countries is inadequate, especially in stream water affected by urban effluents and runoff. The purpose of this study was to investigate heavy metal contaminants in the Nakivubo Stream water in Kampala, Uganda. Water samples Nakivubo Channelized Stream, tributaries and industrial effluents that drain into the stream were collected and analysed for the total elemental concentration using flame atomic absorption spectrophotometer. The results showed that: 1) the wastewater was highly enriched with lead and manganese above the maximum permissible limit; 2) the levels of dissolved oxygen were below the maximum permissible limit, while the biological oxygen demand was above the maximum permissible limit. All industrial effluents/wastewater were classified as strong (> 220 mg/L). Factor analysis results reveal two sources of pollutants; 1) mixed origin or chemical phenomena of industrial and vehicular emissions and 2) multiple origin of lead (vehicular, commercial establishment and industrial). In conclusion, Nakivubo Channelized Stream water is not enriched with heavy metals. These heavy metals (lead, cadmium and zinc) were rapidly removed by co-precipitation with manganese and iron hydroxides and total dissolved solids into stream sediments. This phenomena is controlled by pH in water.     

Treatment of polluted river water by a gravel contact oxidation system constructed under riverbed

The objective of this study was to evaluate the treatment efficiency of a gravel contact oxidation treatment system which was newly constructed under the riverbed of Nan-men Stream located at the Shin Chu City of Taiwan. The influent and effluent water samples were taken periodically for the analyses of pH, temperature, dissolved oxygen, total suspended solids, five-day biological oxygen demand, NH₄ ⁺-N. The results showed that the average removal rates of five-day biological oxygen demand, total suspended solids and NH₄ ⁺-N were 33.6% (between ?6.7% and 82.1%), 56.3% (between ?83.0% and 93.4%) and 10.7% (between ?13.0% and 83.3%), respectively. The calculated mean first order reaction rate constant for five-day biological oxygen demand was 4.58/day with a standard deviation of 4.07/day and for NH₄ ⁺-N was 2.15/day with a standard deviation of 5.68/day. Therefore, it could be said that this gravel-contact-oxidation system could effectively remove biological oxygen demand, total suspended solids, and NH₄ ⁺-N in river water at a relatively short hydraulic retention time, although its pollutant treatment efficiency was not quite stable. However, to reach better or more stable treatment efficiency, aeration might sometimes be necessary to increase the dissolved oxygen in influent river water. And, longer hydraulic retention time of the system might also be required to increase NH₄ ⁺-N removal efficiency.     

河套灌区西部浅层地下水咸化机制

浅层地下水水位埋深浅、含盐量高,是导致河套灌区土壤次生盐渍化的重要原因.以河套灌区西部地区为研究区,通过对浅层地下水的水化学和氢氧同位素特征分析以及水文地球化学模拟,探讨了灌区浅层地下水的补给来源和主控水-岩作用过程,并定量估算了蒸发作用对浅层地下水含盐量的影响.研究区内浅层地下水为弱碱性咸水,pH为7.23~8.45,总溶解性固体（total dissolved solids,TDS）变化范围为371~7 599 mg/L;随着地下水咸化程度增大,水化学类型由HCO₃-Na·Mg·Ca型向Cl-Na型过渡.引黄灌溉和大气降水是浅层地下水的主要补给来源,径流过程中浅层地下水受蒸发作用和植物蒸腾作用影响,地下水化学组分主要来源于蒸发盐溶解和硅酸盐风化水解,并受强烈的蒸发作用和离子交换作用影响.水文地球化学模拟和主成分分析结果显示,蒸发作用和岩盐溶解作用对区内浅层地下水咸化贡献最大,石膏和白云石等矿物的溶解、硅酸盐的水解、Na-Ca离子交换以及局部地形起伏对地下水咸化过程也有较大贡献.      

A preliminary mass balance model of primary productivity and dissolved oxygen in the Mississippi River Plume/Inner Gulf Shelf Region

A deterministic, mass balance model for phytoplankton, nutrients, and dissolved oxygen was applied to the Mississippi River Plume/Inner Gulf Shelf (MRP/IGS) region. The model was calibrated to a comprehensive set of field data collected during July 1990 at over 200 sampling stations in the northern Gulf of Mexico. The spatial domain of the model is represented by a three-dimensional, 21-segment water-column grid extending from the Mississippi River Delta west to the Louisiana-Texas border, and from the shoreline seaward to the 30–60 m bathymetric contours. Diagnostic analyses and numerical experiments were conducted with the calibrated model to better understand the environmental processes controlling primary productivity and dissolved oxygen dynamics in the MRP/IGS region. Underwater light attenuation appears relatively more important than nutrient limitation in controlling rates of primary productivity. Chemical-biological processes appear relatively more important than advective-dispersive transport processes in controlling bottom-water dissolved oxygen dynamics. Oxidation of carbonaceous material in the water column, phytoplankton respiration, and sediment oxygen demand all appear to contribute significantly to total oxygen depletion rates in bottom waters. The estimated contribution of sediment oxygen demand to total oxygen-depletion rates in bottom waters ranges from 22% to 30%. Primary productivity appears to be an important source of dissolved oxygen to bottom waters in the region of the Atchafalaya River discharge and further west along the Louisiana Inner Shelf. Dissolved oxygen concentrations appear very sensitive to changes in underwater light attenuation due to strong coupling between dissolved oxygen and primary productivity in bottom waters. The Louisiana Inner Shelf in the area of the Atchafalaya River discharge and further west to the Texas border appears to be characterized by significantly different light attenuation-depth-primary productivity relationships than the area immediately west of the Mississippi Delta. Nutrient remineralization in the water column appears to contribute significantly to maintaining chlorophyll concentrations on the Louisiana Inner Shelf.     

Sources of oxygen demand in the lower San Joaquin River,California

Dissolved oxygen concentration below 5 mg 1⁻¹ has characterized the lower tidal portion of the San Joaquin River downstream of Stockton, California, during the summer and fall for the past four decades. Intensive field research in 2000 and 2001 indicated low dissolved oxygen concentration was restricted to the first 14 km of the river, which was deepened to 12 m for shipping, downstream of Stockton. The persistent low dissolved oxygen concentration in the shipping channel was not caused by physical stratification that prevented aeration from vertical mixing or respiration associated wigh high phytoplankton biomass. The low dissolved oxygen concentration was primarily caused bynitrification that produced up to 81% of the total oxygen demand. Stepwise multiple regression analysis isolated dissolved ammonia concentration and carbonaceous oxygen demand as the water quality variables most closely associated with the variation in oxygen demand. Between these two sources, dissolved ammonia concentration accounted for 60% of the total variation in oxygen demand compared with a maximum of 30% for carbonceous oxygen demand. The Stockton wastewater treatment plant and nonpoint sources upstream were direct sources of dissolved ammonia in the channel. A large portion of the dissolved ammonia in the channel was also produced by oxidation of the organic nitrogen load from upstream. The phytoplankton biomass load from upstream primarily produced the carbonaceous oxygen demand. Mass balance models suggested the relative contribution of the wastewater and nonpoint upstream load to the ammonia concentration in the shipping channel at various residence times was dependent on the cumulative effect of ammonification, composition of the upstream load, and net downstream transport of the daily load.     

Estimating non-point source pollutant loads for the large-scale basin of the Yangtze River in China

Taking advantage of the opportunity provided by the nationally funded Water Resources Integrated Planning and Investigation of China program (WRIPI), a model was established to estimate non-point source pollutant loads in a large-scale basin (ENPS-LSB) on the basis of hydrological processes and pollutant transport. The model made use of Environment for Visualizing Images software (ENVI) and Interactive Data Language (IDL) and took the characteristics of present-day China into account: a huge rural population scattered widely, marginal rural infrastructure and livestock cultivation based on scatter-feeding. The model was divided into two sections: one on dissolved and one on adsorbed pollutant loads. The dissolved loads were divided into four different types: those originating from agricultural fields, urban areas, rural residential areas, and livestock. The study was undertaken in the Yangtze River Basin. The results showed the chemical oxygen demand (COD), the total nitrogen (TN), the total phosphorous (TP), and the ammonia nitrogen (NH₃–N) loads to be 2.6 × 10⁶, 1.6 × 10⁶, 9.3 × 10⁵ and 3.1 × 10⁵ tons, respectively, in the year 2000. The dissolved COD resulted mainly from rural residential areas and livestock; 76.8% of the dissolved TN and 86.4% of the dissolved TP produced were from agricultural fields. The Yangtze River Delta, the lower reaches of the Han River, and part of the Dongting Lake, Taihu Lake and Poyang Lake basins all had relatively high dissolved pollutant loads; adsorbed nitrogen and phosphorus loads were mainly observed in the middle and upper reaches of the Yangtze River Basin. Dissolved loads were most affected by human activity, whereas adsorbed loads were most affected by natural factors. The results showed that the model performed well on large scale, describing pollutant loads effectively. This makes it possible to properly consider not only point source pollutant discharge but also non-point source pollution in the Yangtze River Basin. Combining point source discharge investigation with the ENPS-LSB model could assist environmental management with controlling water pollution.     

Impact of discharge wastewater effluents on the physico-chemical qualities of a receiving watershed in a typical rural community

The qualities of the treated final effluents of a wastewater treatment plant located in a rural community of the Eastern Cape Province of South Africa were assessed over the duration of 12 months. Parameters measured include pH, temperature, electrical conductivity, salinity, turbidity, total dissolved solid, dissolved oxygen, chemical oxygen demand, nitrate, nitrite and orthophosphate levels and these were simultaneously monitored in the treated final effluents and the receiving watersheds using standard methods. Unacceptably, high levels of the assayed parameters were observed in many cases for chemical oxygen demand (7.5–248.5 mg/L), nitrate (1.82–13.14 mg/L), nitrite (0.09–1.3 mg/L), orthophosphate (0.07–4.81 mg/L), dissolved oxygen (4.15–11.22 mg/L) and turbidity (3.68–159.06 NTU) during the study period and are severally outside the compliance levels of the South African Guidelines and World Health Organization tolerance limits for effluents intended for discharge through public sewers into receiving watersheds. The study has revealed that there was an adverse impact on the physico-chemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facility. This poses a health risk to several rural communities which rely on the receiving water bodies primarily as their sources of domestic water. There is need for the intervention of appropriate regulatory agencies to ensure production of high quality treated final effluents by wastewater treatment facilities in rural communities of South Africa.     

Prediction of water quality from simple field parameters

Water quality parameters like temperature, pH, total dissolved solids (TDS), total suspended solids (TSS), dissolved oxygen (DO), oil and grease, etc., are calculated from the field while parameters like biological oxygen demand (BOD) and chemical oxygen demand (COD) are interpreted through the laboratory tests. On one hand parameters like temperature, pH, DO, etc., can be accurately measured with the exceeding simplicity, whereas on the other hand calculation of BOD and COD is not only cumbersome but also inaccurate many times. A number of previous researchers have tried to use different empirical methods to predict BOD and COD but these empirical methods have their limitations due to their less versatile application. In this paper, an attempt has been made to calculate BOD and COD from simple field parameters like temperature, pH, DO, TSS, etc., using Artificial Neural Network (ANN) method. Datasets have been obtained from analysis of mine water discharge of one of the mines in Jharia coalfield, Jharkhand, India. 73 data sets were used to establish ANN architecture out of which 58 datasets were used to train the network while 15 datasets for testing the network. The results show encouraging similarity between experimental and predicted values. The RMSE values obtained for the BOD and COD are 0.114 and 0.983 %, respectively.     

Efficiency assessment of aerobic biological effluent treatment plant treating pharmaceutical effluents

The present paper undertakes a study of the physico-chemical properties and toxic heavy metals content in the untreated and treated pharmaceutical effluents in order to evaluate the working efficiency of industrial effluent treatment plants. The treatment efficiency achieved for various parameters was conductivity (79.94%), alkalinity (93.91%), hardness (87.70%), chloride (89.24%), cyanide (79.66%), phosphate (99.19%), total dissolved solids (85.89%), total suspended solids (96.87%), salinity (52.41%), dissolved oxygen (27.32%), biochemical oxygen demand (83.39%) and chemical oxygen demand (72.21%). The removal efficiency achieved for different heavy metals was Cu²⁺ (79.66%), Ni²⁺ (69.22%), Cr⁶⁺ (80.15%), Pb²⁺ (72.14%), Fe³⁺ (92.59%) and Zn²⁺ (90.61%). The level of biochemical oxygen demand (64 mg L^?1) in the treated effluents was above the limit of 30.0 mg L^?1, chemical oxygen demand level (208 mg L^?1) was close to a limit of 250 mg L^?1, while average Pb²⁺ concentration (0.10 mg L^?1) was on the borderline of maximum permissible limit of 0.10 mg L^?1 set by Central Pollution Control Board for safe discharge of industrial effluent in inland surface water. The average concentration of cyanide (0.01 mg L^?1) in the treated industrial effluent of our study is of great concern to the fisheries of freshwater ecosystem in which the effluents finally get discharged. Based on the results of the present study, it is concluded that the pollution level in the discharged pharmaceutical effluent is of the great concern requiring proper treatment and regular scientific monitoring so as to protect the environmental degradation of water resources and facilitate the propagation of the aquatic life.     

Effect of paper mill effluents on accumulation of heavy metals in coconut trees near Nanjangud,mysore district,Karnataka, India

Physicochemical characteristics of wastewater from one of the paper mills near Nanjangud and the differential accumulation of heavy metals in parts of coconut trees growing in the area irrigated directly by the wastewaters of a paper mill were investigated. The total dissolved and suspended solids of wastewater were 1,136.9 mg/l and 2,185.4 mg/l, respectively. Biological oxygen demand (BOD) expands and COD is beyond the tolerance limit proposed by Indian standards. The concentrations of heavy metals like Cu, Pb, Zn, Ni, Co, and Cd in coconut water, root, and leaf are higher than the limits suggested by World Health Organization. Survival of coconut trees irrigated by polluted waters indicates tolerance to toxic heavy metals. Since coconut forms part of human food chain, accumulation of toxic heavy metals may lead to organic disorders.     

Systematic assessment of electrocoagulation for the treatment of marble processing wastewater

In this study, the treatability of marble processing wastewater by electrocoagulation using aluminum and iron electrodes was investigated. The sample used was from the marble-processing plant in Sivas and its turbidity, suspended solids, chemical oxygen demand and total solids concentrations were about 1,914?NTU, 2,904, 150 and 4,750?mg/L, respectively. The effects of various operating parameters such as initial pH, current density and electrolysis time on turbidity, suspended solids, chemical oxygen demand and total solids removal efficiencies were investigated. The settling characteristics of waste sludge produced and energy and electrode consumption were also determined. The optimum values of initial pH, current density and electrolysis time in electrocoagulation studies carried out using aluminum electrode were found to be 7.8, 30?A/m² and 5?min, respectively. Under these conditions, the removal efficiencies obtained for turbidity, suspended solids, chemical oxygen demand and total solids were 98.5, 99.2, 55.2 and 92.4?%, respectively. Corresponding energy and electrode consumptions were 0.143?kWh/kg SS and 0.010?kg Al/kg SS. For iron electrode, the optimum parameter values were found to be 7.8 pH, 20?A/m² and 5?min, respectively. Under these conditions, removal efficiencies for turbidity, suspended solids, chemical oxygen demand and total solids were determined as 94.3, 99.1, 54.2, and 96.1?%, respectively. Energy and electrode consumptions were 0.0571?kWh/kg SS and 0.0206?kg Fe/kg SS, respectively. Settling characteristics of sludge produced during experiments carried out using both aluminum and iron electrodes were fairly good. The results showed that electrocoagulation method can be used efficiently for the treatment of marble processing wastewater under proper operating conditions.     

电镀企业搬迁后场地调查及其环境影响评价

对上海新区一家刚搬迁的电镀厂场地进行现场采样,评价土壤、地下水和废水的环境状况。土壤样品检测了pH、CN-及主要重金属离子等11项指标,地下水样品分析主量元素、重金属元素、NH3-N、NO3--N、NO2--N、溶解性总固体、总硬度、CN-、挥发性酚类、高锰酸盐指数等24项指标,废水样品检测化学耗氧量(CODCr)、挥发性酚及土壤的分析指标共13项。结果表明:厂区内土壤呈碱性,综合污染指数为0.67,仅个别采样点Zn、Ni的单项污染指数大于1,土壤总体环境质量尚可;地下水的综合评价指数在4.27～7.58之间,水质判断为很差或极差,不能作为饮用水源,主要污染指标NH3-N、氯化物、溶解性固体、总硬度、重金属元素、氰化物、挥发性酚、高锰酸盐指数等都低于地下水Ⅳ级标准,未见明显的重金属污染;废水除了pH之外,重金属元素、挥发性酚和氰化物等指标都达到城市污水和电镀污染物排放标准。研究成果对污染型企业搬迁后的原厂区环境监测评价具有一定的借鉴意义。     

Surface water quality contamination source apportionment and physicochemical characterization at the upper section of the Jakara Basin, Nigeria

The present study investigates the surface water quality of three important tributaries of Jakara Basin, northwestern Nigeria to provide an overview of the relationship and sources of physicochemical and biological parameters. A total of 405 water samples were collected from 27 sampling points and analyzed for 13 parameters: dissolved oxygen (DO), 5-day biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), suspended solids (SS), pH, ammonia-nitrogen (NH₃NL), dissolved solids (DS), total solids (TS), nitrates (NO₃), chloride (Cl), phosphates (PO₄), Escherichia coli (E. coli) and fecal coliform bacteria (FCB). Pearson’s product–moment correlation matrix and principal component analysis (PCA) were used to distinguish the main pollution sources in the basin. Four varimax components were extracted from PCA, which explained 84.86, 83.60, and 78.69 % of the variation in the surface water quality for Jakara, Tsakama, and Gama-Kwari Rivers, respectively. Strong positive loading included BOD₅, COD, NH₃NL, E. coli, and FCB with negative loading on DO attribute to a domestic waste water pollution source. One-way ANOVA revealed that there was no significant difference in the mean of the three water bodies (p?>?0.05). It is therefore recommended that the government should be more effective in controlling the point source of pollution in the area.     

Assessment of the impact of industrial effluents on water quality of receiving rivers in urban areas of Malawi

A study was carried out in Malawi to assess the extent of chemical pollution in a receiving river as affected by industrial effluents. Both the effluents and the water at selected points in the river were analysed for pH, dissolved oxygen, biochemical oxygen demand, electrical conductivity, suspended solids, nitrate, alkalinity, hardness, chloride and phosphate in the dry and rainy seasons. The results showed that the effluents were acidic in both the dry season (range: 4.2 ± 0.02–6.5 ± 0.02) and in the rainy season (range: 4.2 ± 0.05–5.6 ± 0.01). While the levels of dissolved oxygen, biological oxygen demand, electrical conductivity, suspended solids, alkalinity and chloride were relatively high in the dry and rainy seasons, the concentration of phosphate and nitrate were low in both seasons. The water upstream was neutral (average pH, 7.40 ± 0.04) with high dissolved oxygen but low in the levels of the other parameters in both seasons. The water after the effluent receiving points was acidic and the levels of the other parameters were high, especially downstream. The results suggested that the water in the river was polluted and not good for human consumption. It is therefore recommended that the careless disposal of the wastes should be discouraged and although the values in some cases were lower than the allowable limits, the continued discharge of the effluents in the river may result in severe accumulation of the contaminants and, unless the authorities implement the laws governing the disposal of wastes, this may affect the lives of the people.     

Ecological characteristics of Vrishabhavathy River in Bangalore (India)

River Vrishabhavathy, a tributary of Cauvery River was studied for 12 physico-chemical parameters at four sites over a distance of 50 km for a period of 2 years (1999–2001) at monthly intervals. Water was faintly alkaline, with pH showing negative correlation with temperature. The dissolved oxygen content increased downstream with negative correlation to biological oxygen demand (BOD), chemical oxygen demand (COD) and turbidity. Bicarbonate alkalinity was very low compared with carbonate alkalinity. Carbonate alkalinity, total hardness, total dissolved solids, total suspended solids, electrical conductivity, BOD and COD decreased downstream, with an upward trend in the middle reaches due to the introduction of raw sewage. The seasonal and yearly trends are also discussed. The river is a sewer collector undergoing self-purification.     

Sustainable Irrigation with Brackish Groundwater in Heilonggang Region, China

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Assessment of physico-chemical and microbiological surface water quality using multivariate statistical techniques: a case study of the Wadi El-Bey River,Tunisia

Located in the northeastern part of Tunisia, Wadi El Bey drains the watershed through farmland, industrial, and urban areas of the region. It serves to discharge treated wastewater of different types. In this work, the variations of the water quality of Wadi El Bey were studied and evaluated, during 2 years (2012–2013), using multivariate statistical techniques such as principal component analysis (PCA) and cluster analysis (CA). In addition, the similarities or dissimilarities among the sampling points were as well analyzed to identify spatial and temporal variations. The results obtained based on the cluster analysis, led to identify three similar water quality zones: relatively polluted (LP), moderately polluted (MP), and highly polluted (HP). The inorganic and organic parameters, temperature, conductivity, dissolved oxygen, chemical oxygen demand, salmonella, and enterococcus, seemed to be the most significant parameters of water quality. Three factors were identified as responsible for the data structure, explaining 60.95% of the total variance. The first factor is the physical and non-organic chemical parameters explaining 23.48% of the total variance. The second and third factors are, respectively, the microbiological (21.26%) and organic-nutrient (16.2%).This study shows that multivariate statistical methods can help the water managers to understand the factors affecting the water quality.     

Runoff characteristics of non-point pollutants caused by different land uses and a spatial overlay analysis with spatial distribution of industrial cluster: a case study of the Lake Sihwa watershed

To characterize a runoff pattern of non-point pollutants in relation with different land uses in a watershed, a monitoring activity and field measurements were carried out and data points were recorded during the rainfall events for 2 years. The study area includes industrial, urban, and rural sectors, which can represent a model case for the runoff study. Each sector was monitored with methodology and parameters including partial event mean concentration, first flush effect, mass first flush ratios, and correlation analysis. The Banwol Industrial Outfall No. 4 (4TG), an industrial area, showed a strong first flush effect, indicating that pollutants such as suspended solids, chemical oxygen demand, total nitrogen, and total phosphorus, were discharged at the early stage of a storm. An MFF₃₀ analysis of the runoff revealed a mean pollutant load was over 50 %. In the Ansan Stream, an urban area, a strong first flush effect did not appear; however, the concentrations of pollutants reached a peak some time later during a storm event. Then, the concentrations of pollutants quickly reduced. On the other hand, Jangjunbo and Munsan Stream, rural areas, did not exhibit the first flush effects, and when considering the value of MFF₃₀, 30 % or fewer pollutants on average were discharged at the initial stage of a storm. This means most of pollutants were streamed out at the later time of a storm event. The monitoring results found that the runoff characteristics of non-point pollutants in industrial, urban, and rural areas were distinctly different and site-specific. Therefore, each watershed management plan should be prepared to meet its own characteristics. Also, this kind of data can be an important base in designing and sizing a regional wastewater treatment facility to treat pollutants from a contaminated watershed.