赣江水系水化学时空特征及影响因素

Temporal-spatial characteristics of water chemistry and influencing factors in the Ganjiang River

为研究赣江水系水化学的时空特征,于2015年1月、7月采集干流与主要支流水样37个,测定了水体离子浓度.结果表明,各离子浓度排序为:阳离子Ca^(2+)>Na^+>K^+>Mg^(2+)>NH_4^+,阴离子HCO_3^->SO_4^(2-)>Cl^-,水化学类型为HCO_3-Ca型且为弱矿化度水,枯水期离子浓度显著高于丰水期.基于各采样点离子浓度聚类分析结果,将赣江流域在空间上分为3个区域,A1(桃江、袁水和锦江流域)、A2(琴江、梅江、平江、恩江、泸水流域),A3(A1和A2以外的赣江流域).3个区域的总溶解固体(TDS)大小顺序为:A1>A3>A2.从自然因素看,赣江流域的水化学组成主要受到岩石溶滤作用的影响,枯水期A3蒸发作用较明显.受工业和采矿废水影响,A1的NH_4^+、SO_4^(2-)、Cl^-、Na^+含量最高,同时酸性废水的排放促进了溶滤作用,Ca^(2+)浓度也最高;A3受城市生活污水的排放影响明显,Cl^-、Na^+含量较高;A2的各离子浓度最小,水化学组分主要受到岩石溶滤的作用.

To investigate the temporal-spatial characteristics of water chemistry in the Ganjiang River, 37 river water samples in the main streams and tributaries were collected in January and July, 2015 and the ion concentrations were measured. The results showed that the order of cation and anion concentrations was Ca2＋ 〉 Na＋ 〉 K＋ 〉 Mg2＋ 〉 NH4 ＋and HCO3- 〉 SO4 2- 〉 Cl-, respectively. The hydrochemical type was HCO3-Ca with weak water salinity, and the ion concentrations in the dry season were significantly higher than those in the wet season. Based on clustering analysis of the ion concentrations, the Ganjiang River basin was divided into three zones： Al （Taojiang River basin, Yuan River basin and Jinjiang River basin ）, A2 （Qinjiang River basin, Meijiang River basin, Pingjiang River basin, Enjiang River basin and Lushui River basin）, and A3 （other areas beyond the A1 and A2 in the Ganjiang River basin）. The order of total dissolved solid （TDS） in the three zones was A1〉A3〉A2. The main natural factor affecting the hydro-chemical compositions of river water in the Ganjiang River basin was rock leaching, and hydro-chemical compositions were affected by evaporation in the A3 zone in the dry season. The concentration of SO4 2- in A1 zone was the highest due to the influence of the industrial and mining waste water. The concentration of Ca2＋ was also the highest in A1, because of the discharge of acidic water which promoted rock leaching. The concentrations of Cl- and Na＋ in A3 were higher than those in A1 and A2 because of the stronger influence of urban sewage. The concentrations of ions were the lowest in A2 where the hydrochemistry were mainly affected by rock leaching.