滇池主要入湖河流水化学特征及其环境意义

为了给滇池流域水污染治理及水环境修复提供理论依据,选取滇池4条主要入湖河流(盘龙江、宝象河、柴河、捞渔河)为研究对象,同时采集农田排污口5个、城市排污口5个、雨水3个共计13个水样,按照河流流经区的不同土地类型,共布设28个样点,对其水化学特征进行了系统调查,并结合流域土地利用类型,探讨了流域水化学特征对环境的指示意义。结果表明,滇池流域4条主要入湖河流的pH值为6.50～7.77,均值为7.03;电导率(EC)为6.3～85.0 mS/m,均值为33.0 mS/m;总溶解固体(TDS)为40～540 mg/L,均值为210 mg/L,空间上均表现出沿河流自上游向下游递增的趋势;4条主要入湖河水中阳离子以Ca~(2+)为主,占主要阳离子的65%,阴离子则以HCO~-_3为主,占主要阴离子的84%,入湖河流的水化学类型为HCO~-_3-Ca~(2+)型;河道径流主要离子浓度均表现为自上游向下游增加的趋势。Ca~(2+)、Mg~(2+)和HCO~-_3主要指示了研究区地质条件对水环境的作用,K~+、NO~-_3、SO■主要指示了农业活动对水环境的影响,Na~+、Cl~-主要指示城市生活污水排放对水环境的影响。

Water Chemistry in the Primary Tributaries of Dianchi Lake and Effect on the Water Environment of Dianchi Lake

Research on the hydrochemical characteristics of rivers is important for water resource assessment and supports the sustainable use of water resources and environmental conservation of river basins. Dianchi Lake, an urban lake near Kunming, is the largest lake in Yunnan Province and is badly contaminated. In this investigation, we studied the aquatic chemistry of the four primary tributaries of Dianchi Lake by systematic analysis of ions in the water. When the factors affecting water chemistry and quality were analyzed, land use in the basin was considered. The study aimed to provide a scientific basis to support effective pollution treatment and environmental remediation. The investigation was carried out in April 2017 and the four tributaries studied were the Panlong, Baoxiang, Chaihe and Laoyu Rivers. A total of 28 sampling sites were located from the upper reach to the lower reach of the four rivers, flowing through forest, farmland and urban areas. Water samples from 10 outlets (5 from farmland drainage ditches, 5 from urban sewage outfalls) and 3 rainfall samples were collected in the Baoxiang River basin to investigate the primary sources of ions to the river and the influence of land use type on the chemical characteristics of runoff. The ranges of pH, electrical conductivity (EC) and total dissolved solids (TDS) in the tributaries of Dianchi Lake were, respectively, 6.50-7.77, 6.3-85.0 mS/m and 40-540 mg/L, with mean values of 7.03, 33.0 mS/m and 210 mg/L. All three parameters increased from upstream to downstream and their spatial variations reflected the influence of anthropogenic activity on water quality. Ca2+ and HCO3- were abundant, accounting for 65% of the cations and 84% of the anions. The relative abundance of cations followed the order Ca2+>Mg2+>Na+>K+ and the relative abundance of anions was HCO3->SO42->Cl->NO3-. Chemically, the water type is HCO3--Ca2+ and the abundance of the major ions all increased from upstream to downstream. Ca2+, Mg2+ and HCO3- primarily reflected the geology; K+, NO3- and SO42- the agricultural activity and Na+ and Cl- the impact of urban sewage discharge.