Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish Centre for Education and Research, Beijing 10019, China.
Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish Centre for Education and Research, Beijing 10019, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2020 Nov 15;743:140684. doi: 10.1016/j.scitotenv.2020.140684. Epub 2020 Jul 7.
As an important part of the water cycle, the hydrologic process and chemical compositions of groundwater have changed significantly due to the joint influence of climate change and human activities. Groundwater salinization becomes a serious threat to water security in coastal areas. In order to assess the relationships between surface water, groundwater and seawater in the coastal plain, we performed a synthesis study based on hydrochemical-isotopic data, hydro-dynamical records and environmental tracers. Deuterium and oxygen isotopes and water chemical indicators were used to identify pollution status, salt sources and migration processes. Radioactive isotopes and gaseous tracers were used to obtain reasonable groundwater age. With the help of multi-tracer approach, the surface-groundwater interaction, salinization of groundwater and nitrate pollution were identified in the Yang-Dai River plain, northern China. The estimated groundwater ages determined from chlorofluorocarbons (CFCs) and tritium (H) ranges from 18 to 41 years in this area, suggesting a modern groundwater circulation. The spatial distribution of the groundwater age varies significantly due to horizontal hydrogeological heterogeneity. The total dissolved solids (TDS) content of the groundwater near the Well Field (average: 970 mg/L) was higher than the TDS values in samples derived from places located at an equivalent distance to the coastal line (average is 708 mg/L), which resulted from the vertical seawater intrusion through river channels and pollutant inputs from agriculture activities. The nitrate concentrations in groundwater were elevated up to 271 mg/L and increased with increasing groundwater age, which was another water environment problem that should be solved urgently but lacks sufficient attention for years. This study provides a conceptual model with a number of comparable hydrochemical information, which is significant for regional pollution control and water resources management.
作为水循环的重要组成部分，由于气候变化和人类活动的共同影响，地下水的水文过程和化学组成发生了显著变化。地下水盐化成为沿海地区水安全的严重威胁。为了评估沿海平原地表水、地下水和海水之间的关系，我们基于水文化学-同位素数据、水动力记录和环境示踪剂进行了综合研究。氘和氧同位素以及水化学指标用于识别污染状况、盐分来源和迁移过程。放射性同位素和气体示踪剂用于获得合理的地下水年龄。借助多示踪剂方法，在中国北方的洋河-戴家坝平原识别出了地表水-地下水相互作用、地下水盐化和硝酸盐污染。利用氯氟碳（CFC）和氚（H）确定的地下水年龄范围为 18 至 41 年，表明该地区存在现代地下水循环。由于水平水文地质非均质性，地下水年龄的空间分布差异显著。位于井场附近的地下水总溶解固体（TDS）含量（平均值：970mg/L）高于从距海岸线同等距离处采集的水样的 TDS 值（平均值为 708mg/L），这是由于河流通道中的垂直海水入侵和农业活动带来的污染物输入造成的。地下水中的硝酸盐浓度升高至 271mg/L，并随地下水年龄的增加而增加，这是另一个急需解决但多年来缺乏足够关注的水环境问题。本研究提供了一个具有许多可比水文化学信息的概念模型，对区域污染控制和水资源管理具有重要意义。
