摘要
"水质型"缺水问题是新疆喀什地区水资源紧缺的主要原因之一.位于喀什地区西部的喀什三角洲面积13 329 km^2,73. 2%面积的潜水和53. 2%面积的承压水SO4^2-浓度超过地下水质量Ⅲ类标准,同时伴随有高TDS、高硬度等特征.运用δD、δ18O-H2O和δ34S-SO4^2-同位素等手段分析地下水SO4^2-化学特征及来源.结果表明:①区内剥蚀山区钙质粉砂岩、钙质细砂岩和石膏等盐类矿物的溶解控制了流域水化学组成,形成了水化学类型以SO4型为主的地表水和地下水.地下水化学类型演变方向为HCO3·SO4→SO4→SO4·Cl,山麓斜坡冲洪积砾质平原为溶滤-径流带,河流冲积平原为径流-累积带,上游至下游地下水化学成分趋向盐化;②区内地下水初始补给源主要为大气降水,且受一定蒸发作用影响.不同水文地质单元地下水δD和δ18O分布特征明显,上游至下游,同位素值由低到富集,受蒸发作用由弱到强;冲积平原承压水同位素分布较离散,受到上覆潜水混合作用影响;③南部、北部山麓斜坡冲洪积砾质平原潜水SO42-来源分别为海陆交互相和陆相蒸发岩的溶滤;河流冲积平原潜水SO42-除了陆相蒸发岩溶滤来源外,还存在化肥淋滤的污染;承压水受蒸发岩溶滤外,还受到潜水的混合作用和细菌还原硫酸盐作用影响.
Poor water quality is one of the main reasons for a shortage of water resources in the Kashi Prefecture of Xinjiang. The area of the Kashgar Delta is located in the western Kashi Prefecture and covers an area of 13329 km^2. Sulfate concentrations exceed the groundwater quality class III standard in 73. 2% of the unconfined groundwater area and 53. 2% of the confined groundwater area. In addition,the TDS content and the hardness of the water are high. The chemical characteristics and sources of groundwater sulfate were analyzed using the isotope method of δD,δ18O-H O,and δ34S-SO4^2-. The results showed that:① The dissolution of salt minerals such as calcareous siltstone,calcareous sandstone,and gypsum in denuded mountainous areas controlled the hydrochemical compositions in the basin,and formed surface water and groundwater dominated by SO4. The evolution trend of groundwater chemical types was HCO3·SO4 →SO4 →SO4·Cl. Alluvial-proluvial gravel plains on the piedmont slopes were the main dissolution-runoff zones and the fluvial plain was main runoff accumulation zone. The chemical composition of the groundwater tended towards salinization,from upstream to downstream;② The groundwater was mainly derived from atmospheric precipitation,and was affected by evaporation. The distribution of δD and δ18O in the groundwaters of different hydrogeological units was clear;from upstream to downstream,isotope values varied from low to increasingly higher,and evaporation varied from weak to strong,respectively. The distribution of isotopes in the confined groundwater in the river alluvium plain was relatively discrete,which was affected by the mixing effect of unconfined groundwater;③ The sources of sulfate in the unconfined groundwater in the southern and northern alluvial-proluvial gravel plains on the piedmont slopes were the dissolution of marine-terrestrial and terrestrial deposit evaporates,respectively. The sources of sulfate in the unconfined groundwater in the river alluvium plain were the dissolution of terrestrial deposit evaporates and pollution from fertilizer leaching. The confined groundwater was affected by the dissolution of evaporates and the mixing effect of the unconfined groundwater and bacterial sulfate reduction.
作者
魏兴
周金龙
乃尉华
曾妍妍
范薇
李斌
WEI Xing;ZHOU Jin-long;NAI Wei-hua;ZENG Yan-yan;FAN Wei;LI Bin(College of Water Conservancy and Civil Engineering,Xinjiang Agricultural University,Urumqi 830052,China;Xinjiang Hydrology and Water Resources Engineering Research Center,Urumqi 830052,China;NO.2 Hydrogeological and Engineering Geological Team of Xinjiang Bureau of Geology and Mineral Resources Exploration and Development,Changji 831100,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2019年第8期3550-3558,共9页
Environmental Science
基金
国家自然科学基金项目(41662016)
新疆自治区“十三五”重点学科建设高峰学科-水利工程学科基金项目(xjslgcgfxk20161103)
