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江苏洋口港地区是江苏沿海开发重点建设的深水港区,水质优良的地下水是港区经济社会发展的重要基础.本研究利用近期获得的钻孔剖面地层对比数据资料,沿水文径流剖面分层采集水样,通过识别地表水、各含水层地下水的环境同位素(δD、δ~(18)O、~3H、~(14)C)组成指纹特征,以揭示研究区地下水的形成演化规律.结果表明,研究区浅层地下水主要来源于现代大气降水的入渗补给,大气降水在补给地下水过程中经历了明显的蒸发过程;研究区深层地下水的放射性~(14)C年龄主要为15000~26000 a,其稳定同位素δ~(18)O、δD值比现代降水低,是晚更新世末次冰期(大理冰期)的盛冰期降水入渗补给.地下水含水层的氘、氧、碳同位素分布具有明显的呈层性,随着地下水埋藏深度增加,地下水中的δD、δ~(18)O值呈下降趋势.浅层地下水与地表水水力联系紧密,可更新能力较强;深层地下水径流缓慢,总体上处于封闭-半封闭状态,可更新能力弱.江苏沿海平原天然地下水流动是自晚更新世末期以来,伴随着冰退、海平面上升而调整到目前的模式.末次盛冰期以来的自然地理及地质发展史,决定着研究区第四系地下水流系统的演变格局,现代人类活动加强了浅层与深层地下水之间的水力联系.研究在高强度开发地下水条件下的区域水文循环特征,可为沿海地区地下水演变机理和调控研究提供技术支持.
The Yangkou Port of Jiangsu Province is a deep-water port area mainly constructed in the coastal area of Jiangsu Province. Groundwater with good water quality is an important foundation for the economic and social development of the port area. In this study, based on the comparatively obtained data of stratigraphic intervals of drilling sections, The water samples were collected to identify the formation and evolution of groundwater in the study area by identifying the surface water and the environmental isotopes (δD, δ ~ (18) O, ~ 3H, ~ (14) C) of the groundwater in each aquifer. The results show that the shallow groundwater in the study area mainly comes from the infiltration recharge of the modern atmospheric precipitation, and the atmospheric precipitation experienced obvious evaporation during groundwater recharge. The radioactive age of groundwater in the study area is mainly 15000-26000 a , The δ 18 O and δ D values of the stable isotopes are lower than those of modern precipitation and are the recharge of glaciation during the last glacial ice age of the Late Pleistocene (Dali ice age). The distributions of deuterium, oxygen and carbon isotopes in groundwater aquifers are obvious As the depth of groundwater burial increases, the δD and δ ~ (18) O values in groundwater show a downward trend, and the shallow groundwater is closely related to the surface water and has strong renewability. Deep groundwater Slow runoff, generally closed-semi-closed, weak renewable capacity.Jiangsu coastal plain natural groundwater flow since the late Pleistocene, with the ice back, sea level rise and adjust to the current mode since the last ice age The history of natural geography and geological development determines the evolution pattern of the groundwater flow system in the Quaternary of the study area and modern human activities have strengthened the hydraulic connection between shallow and deep groundwater.The study of the regional hydrological cycle under the condition of intensive exploitation of groundwater Features, which can provide technical support for the research on groundwater evolution mechanism and regulation in coastal areas.