八岭山古墓群保护区地下水水化学特征及其对古墓的影响

Hydrogeochemical characteristics of groundwater and its impacts on ancient tombs in Baling Mountain Tomb Group Reserve

湖北荆州八岭山地下埋藏有特大型、大型及中型古墓560余座,具有极大的历史文化价值,然而长期以来对影响古墓保存条件的地下水水文地球化学特征缺乏深入认识,因此,开展该保护区地下水水位动态监测与分析十分必要。基于水文地质调查、地下水水化学、同位素分析和地球化学模拟,识别了八岭山古墓群保护区地下水水文地球化学特征,揭示了地下环境中主要的水文地球化学过程。结果表明:研究区地下水主要来源于大气降雨,雨水经包气带入渗向下依次补给潜水、潜水-承压水、承压水,潜水-承压水经历了一定程度的蒸发过程;地下水pH值范围为6.50~8.06,总体上为微酸性到弱碱性的水环境条件;水化学类型以Ca-HCO_(3)型为主,溶解性总固体(total dissolved solids,TDS)含量范围为149.30~608.56 mg/L,离子组分主要来源于水-岩相互作用;硅酸盐岩的风化溶解以及方解石、白云石的溶解-沉淀平衡和离子交换是八岭山古墓群保护区地下水水化学的主要控制过程;垂向渗滤是八岭山古墓群保护区地下水运移和影响古墓葬埋藏条件的一个重要形式,强烈的水-岩相互作用形成的水环境条件可能对古墓葬埋藏环境产生影响。研究成果可为文物保护和大遗址保护利用提供重要科学依据,也可为地质环境监测服务文化强国提供参考。

There are about 560 super-large,large and medium-size tombs buried in Baling Mountain of Jingzhou in Hubei Province,which contains important historical and cultural significance.However,it is lack of in-depth understanding of the hydrogeochemical characteristics of groundwater that affect the buried conditions of ancient tombs.Thus,it is of great importance to conduct dynamic monitoring and analysis of groundwater level to reveal the potential effect of hydrogeochemistry condition of ancient tombs.Based on hydrogeological survey,groundwater hydrochemistry,stable isotope analysis and geochemical simulation,the authors in this paper identified the hydrogeochemical characteristics of groundwater in Baling Mountain Tomb Group Reserve(BMTGR),and revealed the main hydrogeochemical processes of underground environment.The results showed that the groundwater of BMTGR originated from atmospheric rainfall.The rain water seeped through the aeration zone into the phreatic aquifer,phreatic-confined aquifer and deep confined aquifer in turn,and phreatic-confined aquifer has experienced a certain degree of evaporation.Groundwater pH value ranges from 6.50 to 8.06,showing the sightly acidic to weakly alkaline water environment condition.The main hydrochemical type of groundwater is Ca-HCO_(3) with TDS(total dissolved solid,TDS) range of 149.30~608.56 mg/L,and the ionic components are mainly derived from water-rock interactions.The weathering and dissolution of silicate rocks,calcite and dolomite dissolution/precipitation balance and ion exchange are the dominant control process of groundwater hydrochemistry.Vertical infiltration is an important way of groundwater migration,affecting the burial conditions of ancient tombs in BMTGR.The water environment caused by strong water-rock interaction may affect the buried conditions of ancient tombs.This research could provide scientific basis for the preservation and utilization of cultural relics and large site,and some references for geologic environment monitoring and strong nation of socialist culture.