桂江流域河流水化学特征及影响因素

2012年4月9-16日在桂江流域采集河流水样15个进行分析测试。研究结果表明:(1)桂江河水样品pH值介于6.36~8.46,平均值为7.58;EC范围为18~316μs/cm,平均值为175μs/cm;流域河水SIc平均值为-0.7,其变化受流域碳酸盐岩的分布控制。(2)桂江的水为HCO3-Ca型水,HCO3-和Ca2+平均分别占阴、阳离子的76%和77%,主要来自岩石风化。(3)中游部分河水NO3-和SO42-较高,可能是受工农业等人类活动的影响引起,此外硫酸参与了碳酸盐矿物的溶解。(4)Ca2+、Mg2+和HCO3-总体呈现中游高,上游和下游较低;SO42-和NO3-仅在中游部分受到人类活动影响较多的支流偏高,上下游相对较低且相差不大;Cl-、Na+和K+则呈现出中下游较高,上游较低的特征。 

Hydrochemical characteristics and influencing factors of the river water in the Guijiang

Chemical characteristics of 15 river water samples from the Guijiang are analyzed in April 9-16, 2012. The results show that:(1) The pH values of the river water average in 7.58 and range from 6.36 to 8.46; EC average in 175 μs/cm and range from 18 to 316 μs/cm; the SIc average in -0.7 and change in accordance with the distribution of carbonate rocks in the basin; (2)The hydrochemistry type belongs to HCO3- Ca, and the average HCO3-and Ca2+ contents, accounting for 76% and 77% of all the anions and cations respectively on average, mainly originate from the weathering of rocks; (3) The values of NO3-and SO42-, possibly being affected by human activities such as agriculture and industry, are a little higher in the middle reaches of the Guijiang river; (4)Because of the influence of carbonate rock, the contents of Ca2+, Mg2+ and HCO3-are higher in the middle reaches and lowerin the upstream and downstream generally. The contents of SO42- and NO3- are higher only in the tributaries that affected by human activities in the middle reaches. The contents of Cl-, Na+ and K+ are higherin the middle and lower reaches, but relatively lower in the upper reaches.