| Weihe River is the mother river of Shanxi Section,which is governed synthetically and in great efforts by Shanxi Province in recent years.In order to recognize pollutants pollution characteristics and its origin,it is very essential to analysis long-term variation characteristics of Weihe River,the driving force of pollution and its variation and build the quantitative relationships between the evolution of water pollution and driving force.In this paper,taking Shanxi Section as the object of study,depending on Tongguan bridge Section water quality data published by Ministry of Environmental Protection,Huaxian Section measured and synchronous water quality and quantity of data,and the hydrological data in the Yellow River Basin,depending on statistical data related to Weihe River water environment of Baiji,Xianyang,Xi'an,and Weinan,it uses mean concentration method to calculate loads and analysis characteristics of point sources and non-point sources pollution,uses the mean square deviation weight method to calculate the pollution weight of driving force and builds the quantitative relationships between the evolution of water pollution and driving force.The conclusions are as follows:(1)The value of p H is always between 7 and 8 in 2005~2015,which means the water was alkaline.From 2001,the concentration and load of COD,NH3-N,and TP show downward trend,meanwhile,DO concentration is obviously increasing,which means the management to pollutant in Weihe River is effective and water environment in Weihe River is changing well.Point source concentration and point source proportion of COD,NH3-N,and TP are higher than their non-point source concentration and non-point source proportion which means point pollution is main pollution type of Weihe River in recent years.(2)Concentrations of COD in different quarters have the same variation trend.The concentration of NH3-N is obviously influenced by runoff.DO concentration is showing the trend which is decreased after a increase in the trend.Concentrations of COD and NH3-N in every month is showing Increased after a decrease in the trend.DO concentration reaches top in winter and reaches the lowest during May to August.The value of p H is showing decreased after a increase in the trend.(3)Concentration of pollutant in non-flood period is higher than it in flood period.Concentration of COD and NH3-N decreases with the increase of the peak flow.With the increasing of peak flow,pollutant concentration and its fluctuation range are decreasing.When peak flow is between 480m3/s~680m3/s,Concentrations of COD and NH3-N have the same trend.(4)For water environment driving force factors in every cities in the period of2000~2005?2006~2008 and 2009~2013,the water environment influencing ability of area of water and soil conservation is showing a gradual downward trend,meanwhile,that of per capita public green space and main crop sown area are showing increasing trend.In Shanxi section of Weihe River,discharge standard rate of industrial waste water,sown area of main crops,and reuse ratio of industrial water these three factors always have huge weight.(5)The longer the series of study,the more driving factors that affect the characteristics of pollutants pollution.Population factors,nature factors and urbanization factors are influenced NH3-N concentration significantly.Industrial factors which reflect point source pollution influence COD pollution significantly.Water conservation factors influence non-point source pollution of TP significantly.Industrial factors reflecting cities point source such as reuse ratio of industrial water,agricultural factors reflecting agricultural point source pollution such amount of livestock,and greening effect reflecting underlying surface non-point source influence whole water environment of Weihe significantly. |
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