Comprehensive Water Quality Identification Index Research Articles

Nitrogen and Phosphorus Pollution Discharge and Water Quality Evaluation in a Small Basin of the Upper Reaches of Lijiang River

The Lijiang River Basin is a humid, subtropical, karst landform in China and is listed as a World Heritage Site. However, with the rapid development of urbanization and tourism activities in recent years, it faces increasingly severe non-point source pollution. To understand the temporal and spatial variations in nitrogen and phosphorus pollution discharge and the changes in river water quality, the Jingui Small Basin, in the upper reaches of the Lijiang River, was chosen as a representative system. Changes in nitrogen and phosphorus concentrations were continuously monitored in the main river channel and the river water quality was evaluated using the comprehensive water quality identification index method. The results indicated that there were obvious seasonal changes in nitrogen and phosphorus discharge loads in the basin. Both nitrogen and phosphorus discharge loads were higher in the crop-growing season than in the non-growing season. No significant difference in nitrogen and phosphorus discharge load between different scales was found, and the scale was not the key factor affecting the nitrogen and phosphorus discharge load of Jingui River. As the river flowed from the initial water source to the outlet of the basin, water quality was characterized by the spatial pattern of the upper reaches > the middle reaches > the lower reaches. Except for the water quality at the outlet of the basin in November and December, which reached Class V, the comprehensive water quality of each sub-basin reached the target water quality of the water function zoning from May to December. The elucidation of the nitrogen and phosphorus pollution discharge patterns in the Jingui River and the changes in water quality provide a reference for the control and management of agricultural non-point source pollution in the Lijiang River Basin.

Evaluation of water quality pollution and analysis of vertical distribution characteristics of typical Rivers in the Pearl River Delta, South China

Water quality comprehensive evaluation is an essential technical measure for water environment management and treatment. The previous research methods were often insufficient for studying black-sticking water bodies' formation and transformation mechanisms. In view of this, the single pollution index method and the comprehensive water quality identification index method (Iwq) were used to evaluate the pollution characteristics of rivers; the main pollution factors and sources of the watershed were determined by principal component analysis (PCA), and the vertical stratification characteristics of the water bodies were analyzed. The results showed that the total nitrogen (TN) values of pollutants in typical rivers in the Pearl River Delta were higher than the class V water quality standard, and the ammonia nitrogen (NH3−N) pollution level was the second-highest. TN concentration ranges from 4.27 to 19.83 mg/g, and NH3-N concentration ranges from 2.44 to 15.37 mg/g. In addition, in the monitoring of 15 rivers, 11 of them were the inferior V surface water, including five rivers' comprehensive water quality categories for black-stinking water bodies. This may be related to the process of water self-purification and pollutant transport, and rivers in densely populated areas are often subject to discharge from domestic sewage and industrial sewage. The results of the PCA extracted three principal components (PC), accounting for 88.825% of the total variance, with the first and third PCs controlled by human activities and the second PC influenced by natural sources. There is a more apparent vertical stratification of water bodies here in the typical rivers of the Pearl River Delta, and DO was an important factor affecting the vertical distribution of chemical oxygen demand (COD), NH3-N, TN, total phosphorus (TP), sulfide, Ferrum (Fe), and manganese (Mn). The severe lack of DO in deep water bodies led to elevated levels of NH3-N, Fe, and Mn, and gases such as hydrogen sulfide was released under anaerobic conditions, resulting in eutrophication and black-sticking levels in water bodies.

An ecological environment impact assessment of municipal solid waste based on grey prediction model

Aiming at the problem of low accuracy in the impact assessment of urban waste on ecological environment, a method of urban waste ecological environment impact assessment based on grey prediction model is proposed. First, the pollution type of urban waste is determined, and the important pollution data of urban waste is extracted with the help of the calculation of comprehensive water quality identification index. Then, the total ranking of pollution data is determined by the square root method, the judgement matrix is set to calculate the weight of pollution data, and the urban waste ecological environment pollution index system is constructed. Lastly, with the help of grey prediction model, the positive correlation between urban waste and ecological environment is determined, and the urban waste ecological environment impact assessment algorithm is designed to complete the impact assessment. The results show that the evaluation accuracy can be effectively improved by using the evaluation method in this paper.

Differential characteristics and source contribution of water pollutants before and after the extreme rainfall event in the Huaihe River Basin

Various pollutants are collected into rivers through runoff when rainstorms occur, which can harm the aquatic ecological environment, therefore, strengthening the analysis of river pollution sources before and after rainstorms can reduce the impact of rainstorm runoff periods in regard to the risk from river water pollutants. In this study, the water pollutant differential characteristics and pollution source identification in the Henan section in the Huaihe River Basin were explored before and after the extreme rainfall event, and the monitoring data for nine water quality indicators in the monitoring sections were selected. The changing and differential characteristics and processes of the water quality indicators in the Huaihe River Basin before and after the rainstorm were analyzed by using statistical analytical methods and the comprehensive water quality identification index (IWq), and the absolute contribution rates of pollution sources were calculated by the absolute principal components-multiple linear regression model (APCS-MLR). The results showed that the values of pH, DO (Dissolved oxygen) and EC (Electrical conductance) after the rainstorm were lower than those before the rainstorm, while the turbidity, CODMn (Permanganate index), NH3−N (Ammonia nitrogen), TP (Total phosphorus) and TN (Total nitrogen) increased after the rainstorm. The correlations between pH and DO and other water quality indicators increased after the rainstorm, while the correlations between WT (Water temperature), turbidity, CODMn, NH3−N, TP and TN decreased significantly after the rainstorm. The water pollution of each monitoring section increased after the rainstorm; for example, the water quality conditions at Zhoukou Kangdian (ZKKD), Xihua Zhifang (XHZF) and Suixian Banqiao (SXBQ) increased by 42.11, 36.84 and 25.73% to Class V of the environmental quality standards for surface water in China, respectively. The absolute contribution rates of the PC1 to CODMn and TP were 33.86 and 41.11% before the rainstorm, respectively. The absolute contribution rates of the PC2 to DO and TN were 50.77 and 60.26% after the rainstorm, respectively.

Water quality assessment using optimized CWQII in Taihu Lake

To improve the rationality of weight allocation and weight proportion of different periods in the process of water quality assessment, the comprehensive water quality identification index (CWQII) model was optimized in this study. A new improved comprehensive water quality identification index (ICWQIIG) model based on game theory was established to combine subjective weight and objective weight. Based on ICWQIIG, an improved comprehensive water quality identification index (ICWQIIP) model with phased period combination weights was established to determine determined the weight proportion of phased periods was established. In this study, CWQII, ICWQIIG, and ICWQIIP were used to evaluate the water quality of seventeen sites in Taihu Lake in 2020. The models selected nine water quality parameters and six water quality indicators. The assessment results of water quality classification were between “slightly polluted” and “moderately polluted”. The pollution level on the east bank was lower than that on the west bank and north bank. Furthermore, it was also affected by seasonal change, water quality was worse in January and February but better in October and November. The mean value of Iwq calculated by CWQII, ICWQIIG, and ICWQIIP were 2.405, 2.833, and 3.000, respectively. The compared results showed that the ICWQIIG method can more representative identify the location of polluted water than CWQII. Moreover, the ICWQIIP method calculation results not only retained the representative polluted water samples in the ICWQIIG method but can also identify more pollution sites and worse polluted water bodies. Both ICWQIIG and ICWQIIP had high reliability and accuracy in assessment results, and ICWQIIP was more accurate under sufficient data conditions. This study can offer a scientific basis for local water resource management in Taihu Lake, while simultaneously proposing a science-based and valid methodology for the assessment of other similar water bodies.

Water Quality Evaluation and Spatiotemporal Variation Characteristics of Wenyu River Based on Comprehensive Water Quality Identification Index Method

In recent years, the water environment management of the Wenyu River has yielded positive outcomes. In comparison to earlier, the general water quality has substantially improved. However, some areas’ water quality has not improved as a result of the overall trend of improvement, which has implications for the surrounding areas and the entire water environment. To further explore the water environmental quality of specific river sections, this paper adopts the five monitoring sections of Shahe Gate, Mafang, Lutuan Gate, Xinbao Gate, and the additional sewage outlet in 2019, and the three main water quality indicators of COD, DO, and NH3-N. The water quality of the Wenyu River was evaluated using the comprehensive water quality identification index method, and the characteristics of its temporal and spatial changes were studied using correlation analysis and spatial clustering. The results have shown that the Wenyu River is generally Grade V water during the flood season, and is inferior to Grade V water during the non-flood season. All indicators have a regular time and space distribution and are highly influenced by environmental and human factors. Overall, the water quality of the Wenyu River may essentially reach the water environment function zoning target value. Improvements to the river portions below the Xinbao sluice, as well as the use of rainwater resources, must be prioritized.

Temporal and spatial variability of water quality in an urban wetland and the effects of season and rainfall: a case study in the Daguan Wetland, China.

Urban wetlands provide multiple functions including water treatment, recreation, and education, but they are also highly vulnerable, so it is important to monitor wetland water quality to ensure wetland health. In this study, water quality parameters of an urban wetland and rainfall were monitored at 6 sites for 1year. The correlation analysis of water quality parameters and spatial-temporal variability analysis of water quality were carried out. Besides, the effects of season and rainfall on the wetland water quality were evaluated by the comprehensive water quality identification index (CWQII). These results have shown that there is a significant correlation between nutrient pollutants and Chl-a. Wetland water quality changed with the seasons, but it also varied due to changes in rainfall and location. The water quality of the shallow areas both had high susceptibility and response to seasonal changes and rainfall, but the water quality of the deepwater area was relatively stable. The CWQIIs in different seasons were ranked: Winter (5.98) > spring (4.67) > autumn (4.66) > summer (4.26), and the CWQIIs of different rainfall intensities were ranked: torrential rain (5.09) > heavy rain (4.88) > light rain (4.50) > no rain (4.39) > moderate rain (3.95). The results of this study distinctly explained the effects of season and rainfall on water quality in an urban wetland in a subtropical monsoon climate zone and would be helpful to the policymakers and concerned authorities in developing better water quality management strategies for these wetlands.

Water Quality Assessment and Spatial-temporal Variation Analysis in Yellow River Basin

During the implementation of ecological protection in the Yellow River basin, understanding the water pollution status and spatio-temporal variation of water quality has become the most important thing for water safety in the basin. To analyze the water quality in recent years, the water quality data in the Yellow River basin from 2004 to 2018 were firstly collected from eight typical monitoring stations. Using a combination of multivariate data analysis methods including the Mann-Kendall (M-K) trend test, hierarchical clustering analysis (HCA), principal component analysis (PCA), and modified comprehensive water quality identification index (WQI), the spatio-temporal variation characteristics of the water quality were then explored in the Yellow River basin. The results indicated that in terms of time variation, the HCA from the water quality time series showed that the water quality of the Yellow River basin could be divided into the wet season, normal season, and dry season, being basically consistent with the hydrological period. Combined with the M-K trend test and WQI-based water quality assessment, the water quality of the Yellow River basin was improving gradually, with 2010 as the critical year. The water quality in the wet season was superior to that in the dry season. The pollution indicator NH4+-N and permanganate index were dominant in both the wet season and dry season. According to the spatial variation analysis, the water quality for all the studied stations improved significantly. Spatial clustering showed that the S6 (Shanxi Yuncheng Hejin Bridge) was obviously different from others, and further comparative study demonstrated that S6 was constantly seriously polluted. The S7 (Henan Jiyuan Xiaolangdi) exhibited different characteristics in the wet and dry season. In all stations, NH4+-N was considered to be the most common pollution indicator, whereas the permanganate index and DO were also relatively serious for S6. In different hydrological seasons, NH4+-N and the permanganate index showed different characteristics, and their variety was related to the fact that the former mainly came from domestic and industrial sources, whereas the latter was mainly derived from agricultural sources. The modified WQI showed obvious advantages over single-factor water quality assessment, and the findings from this study can provide scientific evidence for water pollution control and comprehensive water quality management in the Yellow River basin.

Water quality assessment and pollution source analysis of Yaojiang River Basin: a case study of inland rivers in Yuyao City, China

Abstract To fully understand the water quality status of the Yuyao section in the Yaojiang River Basin, we utilized the single factor and comprehensive water quality identification index methods, as well as factor analysis in this study. The single factor water quality assessment results showed that the common parameters exceeding the standard in both the wet and dry seasons included dissolved oxygen and total nitrogen, which were inferior to the target water quality grade III by 1–6 grades. The comprehensive water quality order reaching the target grade III was Hutang River (87.5%), Changling River (50.0%), Yaojiang River (43.8%), and Linzhou River (37.5%). The comprehensive water quality in the dry season (90.0% standard-achieving rate) was better than that in the wet season (25.0% standard-achieving rate). These results suggested that the surface runoff might considerably impact water quality. The factor analysis results showed that the basin surveyed in 2018 was mainly polluted by urban sewage and agricultural sources, while the primary pollution source in 2019 was agricultural pollution. Integrated with comprehensive water quality assessment results, in this study, we demonstrated that the series of water treatment projects carried out in Yuyao City positively impacted municipal sewage treatment.

Correlation Analysis of Landscape Structure and Water Quality in Suzhou National Wetland Park, China

The newly issued “Guideline of General Planning of Wetland Parks”, China, reclassified the functional zoning of national wetland parks into three categories: conservation areas, restoration and reconstruction areas, and rational utilization areas. Therefore, the country is facing a new round of revision and compilation of the general planning of national wetland parks. The purpose of this paper was to provide information to guide wetland park functional zoning and to formulate the water pollution prevention and control strategy. In this study, 53 sampling points of 6 national wetland parks in Suzhou City were selected. Pearson’s correlation analysis, multiple stepwise regression analysis, redundancy analysis, single factor, and comprehensive water quality identification index methods were used to analyze the effects of wetland landscape types and landscape configuration on water quality. (1) Lakes and rivers in the wetland park had positive ecological effects and should be distributed in each functional zone. (2) Grassland ecology is fragile. Grasslands should be distributed in conservation areas and in restoration and reconstruction areas. (3) Woodland and cultivated land have both ecological and economic benefits. They can be used as ecological buffer and entertainment zones, which are respectively distributed in the restoration and reconstruction areas and in the reasonable utilization areas. (4) Built-up land is highly disturbed by humans. It should only occur in the rational utilization areas and far away from the conservation areas.

Water quality characteristics and assessment of Yongding New River by improved comprehensive water quality identification index based on game theory

The Yongding New River is essential for the water supplies of Tianjin. To date, there is no comprehensive report that assesses the year-round water quality of the Yongding New River Main stream. Moreover, little attention has been given to determining a combined weight for improving the traditional comprehensive water quality identification index (ICWQII) by the game theory. Seven water quality parameters were investigated monthly along the main stream of the Yongding New River from May 2018 to April 2019. Organic contaminants and nitrogen pollution were mainly caused by point sources pollution, and the total phosphorus mainly by non-point source pollution. Dramatic spatio-temporal variations of water quality parameters were jointly caused by different pollutant sources and hydrometeorological factors. In terms of this study, an improved comprehensive water quality identification index (ICWQII) based on entropy weight or variation coefficient and traditional CWQII underestimated the water qualities, and an ICWQII based on the superstandard multiple method overvalued the assessments. By contrast, water qualities assessments done with an ICWQII based on the game theory matched perfectly with the practical situation. The ICWQII based on game theory proposed in this study takes into account not only the degree of disorder and variation of water quality data, but also the influence of standard-exceeded pollution indicators, whose results are relatively reasonable. All findings and the ICWQII based on game theory can provide scientific support for decisions related to the water environment management of the Yongding New River and other waters.

Are the Water Quality Improvement Measures of China's South-to-North Water Diversion Project Effective? A Case Study of Xuzhou Section in the East Route.

Xuzhou is the hub city of the east route of China’s South-to-North Water Diversion (SNWD) project and implemented dozens of measures to ensure the water quality security of the water transmission line. In order to detect the effectiveness of water quality improvement measures, the monthly water quality data of five water quality parameters from 2005 to 2015 of six state-controlled monitoring sites in Xuzhou section were selected for analysis. The results showed that the water quality improved from 2.95 in 2005 to 2.74 in 2015, as assessed by the comprehensive water quality identification index (CWQII), and basically reached the Class III standards of China’s Environmental Quality Standard for Surface Water (GB3838-2002) from 2011 to 2015. The trend analysis showed that the decline of ammonia nitrogen (NH3-N) was the most obvious among the five water quality parameters. However, the concentrations of phosphorus (TP) showed significant upward trends at three sites. The positive abrupt change of time series of water quality occurred in 2009–2011. The identification of influencing factors of water quality changes by multivariate statistical methods found that the urbanization factor accompanied by a decrease in agricultural nonpoint source pollution emissions and the enhancement of wastewater treatment capacity, the closure of factories with substandard emissions and precipitation were the major influencing factors of most water quality parameters, which confirmed the effectiveness of measures for water quality improvement in Xuzhou.

Evaluating ecological health in the middle-lower reaches of the Hanjiang River with cascade reservoirs using the Planktonic index of biotic integrity (P-IBI)

Operation of the middle route of the South-to-North Water Diversion Project in the Hanjiang River, China, has made the environmental health downstream of the Danjiangkou Reservoir an important issue for people living along the river. This study used the Planktonic Index of Biotic Integrity (P-IBI) including phytoplankton and zooplankton to evaluate riverine ecological health in an area with cascade reservoirs. Plankton and water samples from 19 sampling sites were collected along the middle-lower reaches of the Hanjiang River in Nov. 2017 and July 2018. To further verify the reliability of the P-IBI results, they were compared with the Saprobic Index (SI) and Comprehensive Water Quality Identification Index (CWQII). Redundancy analysis (RDA) was used to evaluate correlations and variability between P-IBI, SI, CWQII, candidate metrics, and primary environmental factors in the dry and wet seasons. The results showed that the ecological health of the aquatic ecosystem was ‘fair’ in status, oligotrophic, and class II (wet season)-class III (dry season) as evaluated by the IBI, SI, and CWQII, respectively. The ecosystem during the wet season was in better health than that in the dry season: based on CWQII, water quality at 63% of sites was in class III during the dry season, while 79% of sites were in class II in the wet season; and 11% more sites had IBI-A values (the mean values of Phyto-IBI and Z-IBI) less than 3 IBI scores (indicating “fair” status) in the dry season compared to the wet season. Ecological conditions were also poorer in the reservoir backwater area. The main driving forces impacting aquatic ecosystem in the study area were pollutant emissions and dam impacts. This study demonstrated that the P-IBI is a potential tool for evaluating riverine ecological health in areas with cascade reservoirs.

Water pollution characteristics and analysis of Chaohu Lake basin by using different assessment methods.

In the context of the water environmental protection and local economic sustainable growth, it is of great importance to conduct a comprehensive water quality assessment in Chaohu Lake basin. In this study, dissolved oxygen (DO), permanganate index (CODMn), 5-day biochemical oxygen demand (BOD5), ammonia nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP) were investigated monthly at 24 sampling sites in Chaohu Lake basin during 2015 to 2017. Five methods were used to evaluate water quality and identify dominant pollutants. Results showed that the dominant pollutants in Chaohu Lake were TN (4.17~11.61mgL-1) and TP (0.27~0.75mgL-1). The upstream of Chaohu Lake was influenced by Nanfei River, Shiwuli River, and Paihe River, and water quality of the upstream (eutrophic) was worse than that of the downstream (mesotrophic) part of Chaohu Lake. Comprehensive Water Quality Identification Index Method (CWQII) can better assess the water quality compared with the other methods by providing qualitative and quantitative analysis. The index values assessed by CWQII method for Nanfei River, Shiwuli River, and Paihe River were 5.819, 5.986, and 5.141, respectively, and water quality were all assessed as grade V. Overall, water quality of Chaohu Lake has been slightly improved during 2015~2017, but water quality of western inflowing rivers was still heavily polluted. These findings provide valuable information and guidance for water pollution control and water resource management in Chaohu Lake basin. Several feasible measures are proposed.

Water quality assessment in China Ningxia Section of the Yellow River using water quality identification index method

The water quality of the Yellow River is related to the healthy development of industry and agriculture in Ningxia. According to the Ningxia Water Resources Bulletin 2012-2017, we selected three representative water quality indicators of ammonia nitrogen (NH3-N), total phosphorus (TP) and permanganate index (CODMn, and applied the single-factor and comprehensive water quality identification index method to evaluate the water quality of six national control sections in the Ningxia section of the Yellow River. The results showed that each section was most affected by NH3-N, followed by TP, and least affected by CODMn; The single-factor identification indexes of six sections were mostly falls into the category II, and the comprehensive identification indexes showed that the water quality mainly fell into the category II; Affected by the rapid development of the industry in this region, the water quality of the Mahuanggou section was seriously polluted.

Water Quality Assessment for Deep-water Channel area of Guangzhou Port based on the Comprehensive Water Quality Identification Index Method

The comprehensive water quality identification index method is able to assess the general water quality situation comprehensively and represent the water quality classification; water environment functional zone achieves pollution level and standard objectively and systematically. This paper selects 3 representative zones along deep-water channel of Guangzhou port and applies comprehensive water quality identification index method to calculate sea water quality monitoring data for different selected zones from year 2006 to 2014, in order to investigate the temporal variation of water quality along deep-water channel of Guangzhou port. The comprehensive water quality level from north to south presents an increased trend, and the water quality of the three zones in 2014 is much better than in 2006. This paper puts forward environmental protection measurements and suggestions for Pearl River Estuary, provides data support and theoretical basis for studied sea area pollution prevention and control.

The characteristics and evaluation of water pollution in Ganjiang Tail River

The water quality in Ganjiang River has an important impact on the ecological environment of Poyang Lake, because Ganjiang River is an important water supply of Poyang Lake. In this paper, the electrical conductivity (ED), turbidity (NTU), suspended solids (SS), total phosphorus (NP), total nitrogen (NT), ammonia nitrogen (NH4-N), nitrate nitrogen (NO3-N), and chemical oxygen demand quantity (COD) have been considered as indicators of water quality while performing an assessment of water in Ganjiang River. We evaluated and analyzed comprehensively the quality of surface and underground water by using the Water Quality Identification Index Method. The sample water was retrieved every 50 days from eight monitoring points located in three sections of downstream Ganjiang River in Nanchang city; the study was conducted from September 10, 2015 to June 1, 2016. The results indicate that the pollution index of northern, central, and southern tributaries in Ganjiang River downstream are 3.807, 3.567, and 3.795, respectively; these results were obtained by performing the primary pollutants quality identification index method (PP-WQI); the pollution index for the same tributaries was found to be 3.8077, 3.5003, 3.7465, respectively when we performed comprehensive water quality identification index method (CWQI). The water pollution grades are between level 3 and level 4. The main pollutants are COD, TN, and SS; moreover, there is a linear relationship between the pollution index in groundwater and surface water. The water quality is the best in the central branch, and worst in the south; the water quality is moderate in the north. Furthermore, the water of upstream is better than that of downstream. Finally, the water quality is worst in summer but best in winter.

Macroinvertebrates community structure and water quality assessment in the North Canal River Basin, Beijing, China

为全面了解北运河水系的底栖动物群落结构和水环境质量，于2015年5月对北运河水系33个样点的底栖动物和水体理化性质进行了调查，分别采用综合水质标识指数法和底栖动物BI指数法对北运河水系进行水质评价，并通过Kolmogorov-Smirnov检验判断正态性，用Pearson相关分析方法对两种评价结果进行比较和分析.结果表明：北运河水系共采集到底栖动物23种，隶属于3门4纲6目11科11属，以水生昆虫和软体动物为主，整个水系底栖动物群落结构单一；底栖动物BI指数法的评价结果显示，72%的采样点水质为中污染（Ⅳ）或重污染（Ⅴ）；综合水质标识指数法的评价结果显示，超过57%的采样点水质为Ⅳ类及以下；根据K-S检验，两组评价得分均符合正态分布；Pearson相关分析显示两种评价结果呈显著正相关.两种评价结果总体上呈现出相同的趋势，均显示北运河水系整体水质状况较差，干流水质状况优于支流，上游水质状况优于下游，温榆河上游、坝河下游、通惠河上游和凉水河的水质状况较差，温榆河源头和坝河上游的水质状况较好.两种评价结果在个别点位存在一定差异，具体表现为基于水体理化因子的评价结果稍优于水质生物评价结果，造成这种差异的原因是两种评价方法在时空尺度上存在差异.针对城市化水平较高、人类活动干扰较强的北运河水系，同时采用这两种评价方法有助于全面了解其复杂的水环境质量.;Macroinvertebrates as a biological indicator of aquatic health condition plays an important role in the protection and management of water ecological environment. Macroinvertebrates and water quality were investigated on the basis of samples collected at 33 sampling sites in the North Canal River Basin in May 2015. The community structure of macroinvertebrates was analyzed. The comprehensive water quality identification index and Biotic Index of macroinvertebrates were used to assess the water quality in the North Canal River Basin. The results obtained by using these two methods were compared each other by using the Kolmogorov-Smirnov test and Pearson correlation analysis. In this study, a total of 23 species of macroinvertebrates belonging to 3 phylum, 4 class, 6 order, 11 family and 11 genera were identified in the North Canal River Basin, which mainly represented by aquatic insects and molluscs. The community structure of macroinvertebrates in the whole basin was simple. The result of Biotic Index showed that 72% of the sampling sites were moderately(Ⅳ) or seriously(Ⅴ) polluted and comprehensive water quality identification index showed that more than 57% of the sampling sites were worse than Class Ⅳ. The K-S test showed that the results were confirmed to normal distribution and Pearson correlation analysis exhibited that the results of these two methods had a significant positive correlation. The two results had the same tendency generally. Depending on the results, the water quality in the North Canal River Basin was poor. The main stream was better than the tributaries and the upstream was better than the downstream. The water quality in the upstream of the Wenyu River, the downstream of the Ba River, the upstream of the Tonghui River and the Liangshui River were poor while the headwater of the Wenyu River and the upstream of the Ba River were excellent. The result of comprehensive water quality identification index was a little better than that of Biotic Index. This was attributed to the reason that the two assessment methods focused on different spatial and temporal scales. In the North Canal River Basin with high urbanization level and strong human disturbance, the complex water ecological condition could be better understood with both assessment methods at the same time.

Different methods for the evaluation of surface water quality: The Case of the Liao River, Liaoning Province, China

The water-quality index is a grading system for presenting water-quality data and comparing water of varying quality. It can be used in water quality trend analyses and presents valuable information to policy makers, managers, and other nontechnical people. For exploring water quality and identifying the main pollution parameter in the lower reaches of Liao River, Single Factor Evaluation (SFE) method in the form of a Comprehensive Water Pollution Index (CWPI), the Nemerow-Sumitomo Water Quality Index (NWQI), and the Comprehensive Water Quality Identification Index (CWQII) method were used to evaluate water quality in lower reaches of Liao River, Liaoning province, China. The results proved that at Zhaoquan river and Wailiao river the water quality status was good, and Pangxiegou river and Qingshui river showed unsatisfactory water quality status. The major pollution indicator in lower reaches of Liao River was petroleum, and compared with the other assessment methods, CWQII was found to give more useful and objective information, and it is worth further promoting water quality inspections in lower reaches of Liao River. Finally, according to the distribution of industry in the Liao river basin, this study makes some relevant suggestions for sustainable development in the future.

Spatial and seasonal variations of water quality in the upstream plain river networks of the Taihu Basin

在太湖流域上游的宜溧洮滆水系主要河道设置67个监测点，分别于2014年1月（冬季）、4月（春季）、8月（夏季）、11月（秋季）进行水质监测，采用多元统计方法分析了水质的空间差异性和季节性变化，并利用水质标识指数法对水环境质量进行评价.结果表明，宜溧洮滆水系污染程度较严重，总氮（TN）、总磷（TP）和高锰酸盐指数（COD_Mn）浓度年均值分别为4.93、0.26和7.63 mg/L；单因素多元方差分析和聚类分析显示污染物浓度具有显著时空差异性，时间上冬、春季污染程度较高而夏、秋季较低，空间上无锡和常州氮、磷污染较为严重，宜兴和溧阳市有机污染程度较高；水质标识评价结果显示流域内水质基本为IV类或V类，其中TN、TP及COD_Mn是关键污染指标.;Sixty-seven water sampling sites in the Yili-Taoge plain river networks of the upstream area of the Taihu Basin were set to characterize its water quality with spatiotemporal distribution. Water sampling trips were conducted in January (winter), April (spring), August (summer), November (autumn) of 2014, and main water quality parameters were concentrated on nutrients and organic matters. Spatial and seasonal variations of water quality were analyzed by using the multivariate statistical methods and water quality were assessed by employing the comprehensive water quality identification index. The results indicated that pollution degree in the research area was severe. The averaged concentrations of total nitrogen (TN), total phosphorus (TP) and permanganate index (COD_Mn) were 4.93 mg/L, 0.26 mg/L and 7.63 mg/L, respectively. One-way multivariate analysis and cluster analysis showed significantly spatiotemporal patterns of pollutants. Pollution levels in winter and spring were higher than that in summer and autumn. Pollution of nitrogen and phosphorus were heavier in the Wuxi and Changzhou areas, whereas organic matter pollution was more serious in the Yixing and Liyang areas. Water quality in the upstream plain river networks can meet the criteria of Grade IV or V of National Standards for Surface Water Quality, characterized by pollution of TN, TP and COD_Mn.