太湖北部流域水化学特征及其控制因素

Water chemistry characteristics and controlling factors in the northern rivers in the Taihu Basin

为了解太湖北部流域主要河网区水质受该流域地质状况、岩石和土壤的化学风化作用以及人类活动的影响等方面,对太湖北部流域河网区主要河道水体中的主要离子进行了采样研究。结果表明:太湖北部流域水体中的TDS平均值为355.74mg·L-1,变化范围为276.08～681.54mg·L-1,其中Ca2+和HCO3-是占绝对优势的离子,分别占阳离子和阴离子总量的46.2%和48.9%;其次是Na+和SO42-,分别占阳离子和阴离子总量的35.9%和27.5%。进而判断出该流域水化学类型是以碳酸盐岩石和蒸发岩来源为主的HCO3--Ca2+-Na+型。再从离子的自然起源和人类活动角度分别对水化学类型的控制因素进行分析,一方面利用吉布斯分布模式投点作图得出结论:其离子自然起源的优势机制是岩石的风化作用,而蒸发-结晶和大气降水的输入作用十分微弱,这与该流域的水文、地理、地质背景相一致;另一方面通过SPSS软件的相关关系分析得出结论:NO3-、SO42-、K+、Ca2+和Mg2+的相关性较强,与Cl-也呈正相关,说明水体中这些主要离子都具有共同的来源,其中NO3-的较高含量(平均值为14.74mg·L-1)反映了该流域受人类影响较大。尤其是NO3-与SO42-的相关性达到0.83,再次说明氮污染对该流域水体的酸化和水质变化有较大影响。

This paper has studied the major ions of the water of northern rivers in the Taihu Basin in order to understand the geo- logical conditions, rocks and soils of the Taihu Basin and human impacts on the water quality of this drainage. The results show that the average TDS is 355.74 mg.L-1 （changes in the range of 276.08 - 681.54 mg.L-1） in water of northern rivers in the Taihu Basin, in which Ca2＋ and HCO3 is the dominant ions, accounted for 46.2% and 48.9% of total cations and anions respectively; followed by the Na＋ and SO42-, accounted for 35.9% and 27.5% respectively. The aquatic chemistry of northern river in the Taihu Basin is dominated by the weathering of carbonates and mainly the type of HCO3- Ca2＋- Na＋. And from the results above and Gibbs distribution pattern, we conclude that the major origin of water ions is the weathering of rocks, evaporation-crystallization and precipitation inputs are very weak. NO3-, SO42 , K＋. Ca2＋ and Mg2＋ reveal a very strong correlation, and also have a positive correlation with the CI through the SPSS software analysis. They indicate that the chemical components of water are obviously influenced by human influence. Especially the high NO3concentration （average NO3 14.74 mg.L1） and the correlation between NO3- and SO42＋ reached 0.83, which shows that nitrogen pollution and the water quality changes have affected the water acidification.