察尔汗盐湖补给河流河水重金属含量与风险评价

The Content and Risk Assessment of Heavy Metals in the Surface Water of the Recharge Rivers in Qarhan Salt Lake

中文关键词:  察尔汗盐湖  河流  重金属  水体质量  生态风险

英文关键词:the Qarhan Salt Lake  Rivers  Heavy metals  Water quality  Ecological risk

中文摘要:

      察尔汗盐湖是中国最大的盐湖，具有重要的经济价值和生态价值，保证该盐湖补给河流的水体质量对于盐湖资源及盐湖区生态环境保护具有重要作用。本文对察尔汗盐湖主要补给河流开展水化学和重金属元素分析（As, Hg, Pb, Cd, Cu, Ni, Zn），尝试揭示其分布特征并评价重金属元素生态环境风险。水化学分析结果表明，研究区水体整体上偏碱性，河流阳离子以Na+为主，阴离子以Cl-为主，水化学类型主要为Cl·SO4-Na型。重金属分析结果显示，地表水中Hg的标准达到地表水IV类水质要求，而其余重金属均属于地表水Ⅰ类标准，高含量的Hg需引起一定程度的重视。除全集河中Ni属于中等污染外，其余河流重金属属于低污染水平；研究区地表水水体清洁无污染。水体质量指数均小于100，各河流地表水水体质量好，水质清洁无污染。各河流地表水所有采样点中七种重金属的潜在生态风险值均低于150，其综合潜在生态风险为低风险。通过对单一生态风险指数比较，河流地表水中Hg风险值最大，其次为Ni。本研究可为青藏高原河流生态环境安全评估提供一定的科学依据。

英文摘要:

      The Qarhan Salt Lake is the largest in China, and has important economic and ecological values. Therefore, it is important to ensure the quality of the recharge rivers of the salt lake, which is essential for the conservation of the ecosystem in the lake catchment. In this paper, the hydrochemical and heavy metal (HM) elements (As, Hg, Pb, Cd, Cu, Ni, Zn) in the main recharge rivers of the Qarhan Salt Lake were analyzed to reveal their distribution characteristics and the eco-environmental risks of HMs. The results of hydrochemical analysis showed that the river water in the study area was alkaline. The main cation and anion in the rivers were Na+ and Cl-, and the main hydrochemical type was Cl·SO4-Na. The analysis of HM concentrations showed that the standard of Hg in surface water meets the requirement of surface water class IV, while the other HMs belong to class I. The high content of Hg should be paid more attention. The contamination factors showed that the HMs in all rivers were at low pollution levels except Ni in the Quanji River. The modified degree of contamination index, the heavy metal pollution index and the heavy metal evaluation index were used to evaluate the pollution degree of HMs in the surface water of the study area, suggesting that surface water in the study area was clean and non-polluted. The water quality index values were less than 100, showing that the surface water quality of each river was good, the water quality was clean and no pollution. The potential ecological risk values of seven HMs in all sampling sites of surface water were below 150, which was low risk. By comparing the single ecological risk index, the value of Hg in surface water was the highest, followed by Ni. This study can provide a scientific basis for the safety of rivers' ecological environment on the Qinghai-Tibet Plateau.