鞍山-海城地区地震地下水地球化学研究

Seismic-geochemistry of Groundwater in the Anshan-Haicheng Area,Liaoning Province

摘要:

通过测量辽宁省鞍山-海城地区地震重点监测区地下水离子浓度和氢、氧同位素组成，讨论了该区地下水化学类型的时空变化及其成因。测量结果表明，取样点水温变化范围为11.0～97.0℃，水样的总固溶物（TDS）在197.89～829.99mg/L之间，水样分为8种化学类型。大部分水样的δD、δ¹⁸O值均沿中国东北地区大气降水线分布，少数有所偏离，表明该区的地下水主要接受大气降水的补给，并可能有深部水的供给。研究区Ca-HCO₃和Ca·Mg-HCO₃型水主要是岩石风化溶解和阳离子交换作用的结果；Ca-HCO₃·Cl和Ca·Na-Cl·SO₄型水主要受岩石风化溶解、阳离子交换作用、深部卤水混入或人类活动影响；Ca-HCO₃·SO₄和Ca-SO₄·HCO₃型水与岩石风化溶解以及深部流体混入有关；Na-SO₄·HCO₃和Na-HCO₃·SO₄型水主要是深部来源水体的混入造成的。采样期间研究区发生2次M_L≥3.0地震，采样点在地震发生月份出现了明显的离子浓度异常变化；Na⁺、Mg²⁺、Ca²⁺、Cl^-和SO₄^2-浓度变化明显，对地震活动响应较灵敏。

Abstract:

The spatial and temporal variations of groundwater chemical types and their genesis were discussed by measuring ion concentration and hydrogen and oxygen isotopic compositions in the Anshan-Haicheng area,Liaoning Province. The measurements showed that the water temperatures ranged from 11.0℃ to 97.0℃,and the total dissolved solids(TDS)of the water samples ranged from 197.89mg/L to 829.99mg/L. The water samples can be divided into 8 chemical types. The δD and δ¹⁸O values of the most water samples are distributed along the atmospheric precipitation line in the eastern monsoon region of China. A few deviations indicated that the well water in the study area was mainly recharged by atmospheric precipitation,but the hot spring water mixed with small amount of deep fluids. The Ca-HCO₃ and Ca·Mg-HCO₃ waters resulted mainly from rock weathering dissolution and cation exchange;Ca-HCO₃·Cl and Ca·Na-Cl·SO₄,waters from rock weathering dissolution with deep brine mixing or likely sewage pollution;Ca-HCO₃·SO₄ and Ca-SO₄·HCO₃ waters from rock weathering dissolution and deep fluid mixing;Na-SO₄·HCO₃ and Na-HCO₃·SO₄ waters from atmospheric precipitation with the mixing of deep source fluids. The obvious chemical anomalies of the ground waters were well correspond to two earthquakes of M_L ≥ 3.0 in the study area during the sampling duration. The Na⁺,Mg²⁺,Ca²⁺,Cl^-,and SO₄^2- can be considered as the sensitive indicators to local seismic activity.