鄱阳湖流域水化学主离子特征及其来源分析

CHARACTERISTICS OF MAJOR IONS AND THE INFLUENCE FACTORS IN POYANG LAKE CATCHMENT

系统采集了鄱阳湖流域湖水、河水,分析测定各单元水体主离子组成.结果表明,鄱阳湖流域枯水期主离子浓度大于丰水期主离子浓度,TDS集中在60—100 mg.L-1,属于弱矿化度水;总硬度浓度40—60 m.gL-1,属于软水;其中Ca2+和SO24-是占绝对优势的离子,分别占阳离子和阴离子总量的45.0%和47.5%.湖区阴阳离子主要以SO24-和Ca2+为主,湖区的水化学类型为HCO3--Ca2+和SO24--Ca2+;河流的阴阳离子以SO24-、HCO3-和Ca2+为主,其水化学类型为受碳酸盐岩和蒸发岩溶解作用的影响较大的HCO3--SO24--Ca2+.鄱阳湖流域丰水期受大气降水和岩石风化影响显著,枯水期由于降雨量大大减少,鄱阳湖流域水化学成分此时主要受岩石风化和蒸发沉淀作用的影响,此时组分点分布在G ibbs图的中部偏向蒸发-沉积区域.通过SPSS软件做离子的相关性分析,各离子之间的相关系数都呈正相关,说明它们之间有共同的来源;各个离子与各产业之间的相关性均为负,除SO24-与第一产业和第二产业的相关性达到|r|>0.3,人类活动对水化学类型影响很小.

The geochemistry of major ions in the water in Poyang Lake catchment was studied.The results showed that the concentrations of the major ions in dry period were greater than that in the flood period.The density of TDS was in the range of 60—100 mg·L-1,which falls into the catogory of low-salinity water.The total hardness of water was in the range of 40—60 mg·L-1,which was in the catogory of soft water.Ca2＋ and SO2-4 were the two major ions,which were 45.0% and 47.5% of the total cations and anions,respectively.The major cation and anion in the lake water were Ca2＋ and SO2-4,and the hydrochemistry type was HCO-3-Ca2＋ and SO2-4-Ca2＋.On the other hand,the major cation and anion in the river water were SO2-4,HCO-3 and Ca2＋,and the main hydrochemical type was HCO-3-SO2-4-Ca2＋,which was mainly influenced by carbonate dissolution and rock evaporation.In the flood period of Poyang Lake valley,rainfall and rock decay are the main influence factors;in the dry period the composition of hydrochemistry was mainly influenced by rock decay and vapor deposition in Poyang Lake catchment because of the great decrease of rainfall.All the component points are clustered in the middle of Gibbs evaporation-deposition zone.SPSS software′s correlation analysis showed that the ions had a very strong correlation with each other,which indicates that the ions may have the same source.Each ion had negative relationship with each industry,except for SO2-4,for which the correlation with primary or secondary industry is ｜r｜0.3.Therefore,human activities had little influence on the hydrochemistry type.