Analysis of Water Quality Variation and Trend in the Ji'an Section of the Ganjiang River

Based on the monitoring data of water quality in the Ji'an section of the Ganjiang River from 2008 to 2018 by the Water Resources Monitoring Center of Ji'an City,single factor evaluation method,comprehensive pollution index method and seasonal Kendall test method were adopted to study and analyze the characteristics of surface water resources and the changing trend of water quality in the river section.The results show that the water quality in the Ji'an section of the Ganjiang River was generally good,and the water quality of each function zone reached the target requirement.The comprehensive pollution index was controlled between 0.21 and 0.40 over the years,and there was no significant change in time and space,and the water quality was relatively stable.The dissolved oxygen and permanganate index tended to improve,and there was no change in five-day biochemical oxygen demand,while ammonia nitrogen and total phosphorus showed an upward trend.The water quality as a whole showed a trend of deterioration.By discussing the influencing factors of the characteristic pollutants,the causes of water quality in the Ji'an section of the Ganjiang River were further analyzed.It is suggested to strengthen the supervision and control of non-point source and point source pollution.

Temporal dimension and water quality control in an emission trading scheme based on water environmental functional zone

Emission trading is one of the most effectivealternatives to controlling water pollution.Water environmentalfunctional zone(WEFZ)is used to determine thewater quality standard and identify the zone boundary foreach river or reach.In this study,a new emission tradingscheme was addressed based on WEFZ,accounting forboth the temporal dimension and water quality control.Atemporal factor of emission trading was proposed based onvariations in the environmental capacity within a year bydividing the year into three periods,including high,normal,and low periods of environmental capacity.Duringeach period,emission trading was implemented exclusively.A water quality-control scheme was suggestedbased on the water quality requirement in the waterfunctional zone,in which the water quality at thedownstream boundary of the zone was required to meetthe water standard following auto-purification in thestream.Two methods of calculating water quality controlare addressed for point-source pollution and non-pointsourcepollution.The calculated temporal dimension andwater quality control were located in Dongxi River of theDaning Watershed in the Three Gorges Watershed.Thehigh period was during June,July,and August,the normalperiod was during April,May,September,and October,and the low period was during January,February,March,November,and December.The results from the waterquality calculation demonstrated that the discharge ofpoint-source and non-point-source pollutions led to anexcess of common contaminants at the downstreamboundary of WEFZ.The temporal and spatial factorsabove should be incorporated into the emission tradingscheme based on WEFZ.

Assessment of river ecosystem health in Tianjin City,China:index of ecological integrity and water comprehensive pollution approach

Evaluation of the river ecological environment can provide a basis for river management and ecological restoration.To conduct a comprehensive health assessment of the rivers in Tianjin,their biological,physical,and chemical indicators are investigated on the basis of 32 river monitoring sites from August to September 2018.The comprehensive pollution and ecological integrity indexes of the rivers are analyzed.Results of the two evaluations,compared to achieve the river ecological environment evaluation,are as follows.1)Index of Ecological Integrity evaluation shows that among the sampling points,18.8%are"healthy",28.1%are"sub-healthy",40.6%are"fair",6.3%are"poor",and 6.3%are"very poor".2)The comprehensive evaluation of the chemical properties of the 32 river ecosystems in Tianjin shows severe overall river pollution and low standard water function area.Of the total sampling sites,16(50%)are heavily contaminated and 10(31.3%)are moderately contaminated.Excessive chemical oxygen demand and ammonia nitrogen are the main causes of water pollution.3)The Index of Ecological Integrity(IEI)has high correspondence with environmental factors.Pearson correlation analysis results show that the IEI index is significantly correlated with permanganate index(R=-0.453;P=0.023<0.05).Analysis results using BEST show that ammonia nitrogen is the best environmental parameter to explain the changes in IEI(R_(ho)=0.154;P=0.02<0.05)and those using RELATE show significant correlation between the biotic index and the environmental parameter matrices(R_(ho)=0.154;P=0.034<0.05).