Using chlorofluorocarbons (CFCs) and tritium to improve conceptual model of groundwater flow in the South Coast Aquifers of Laizhou Bay, China
文献类型：EI期刊论文
| 作者 | Han D. M. ; Song X. F. ; Currell Matthew J. ; Tsujimura Maki |
| 发表日期 | 2012 |
| 关键词 | Recharging (underground waters) Aquifers Brines Chlorofluorocarbons Fluorocarbons Groundwater flow Groundwater pollution Groundwater resources Hydrogeology Mixing Salt water intrusion Seawater Tritium |
| 英文摘要 | The southern coastal plain of Laizhou Bay, which is the area most seriously affected by salt water intrusion in north China, is a large alluvial depression, which represents one of the most important hydrogeological units in the coastal region of northern China. Chlorofluorocarbons (CFCs, including CFC-11, CFC-12 and CFC-113) and tritium were used together for dating groundwater up to 50years old in the study area. There are two cones of depression, caused by intensive over-exploitation of fresh groundwater in the south and brine water in the north. The assigned CFC apparent ages for shallow groundwater range from 8 a to 50 a. A binary mixing model based on CFC-113 and CFC-12 concentrations in groundwater was used to estimate fractions of young and pre-modern water in shallow aquifers and to identify groundwater mixing processes during saltwater intrusion. Discordance between concentrations of different CFC compounds indicate that shallow groundwater around the Changyi cone of depression is vulnerable to contamination. Pumping activities, CFC contamination, mixing and/or a large unsaturated zone thickness (e.g. 20m) may be reasons for some groundwater containing CFCs without tritium. Saline intrusion mainly occurs because of large head gradients between fresh groundwater in the south and saline water bodies in the north, forming a wedge of saline water below/within fresh aquifer layers. Both CFC and tritium dates indicate that the majority of the saline water is from 50 a, with little or no modern seawater component. Based on the distribution of CFC apparent ages, tritium contents plus chemical and physical data, a conceptual model of groundwater flow along the investigated Changyi-Xiaying transect has been developed to describe the hydrogeological processes. Three regimes are identified from south to north: (i) fresh groundwater zone, with a mixing fraction of 0.80-0.65 'young' water calculated with the CFC binary mixing model (groundwater ages 34 a) and 1.9-7.8TU of tritium; (ii) mixing zone characterized by a mixing fraction of 0.05-0.65 young groundwater (ages of 23-44 a), accompanied by local vertical recharge and upward leakage of older groundwater; and (iii) salt water zone, mostly comprising waters with ages beyond the dating range of both CFCs and tritium. Some shallow groundwater in the north of the Changyi groundwater depression belongs to the 50a water group (iii), indicating slow velocity of groundwater circulation and possible drawing in of saline or deep groundwater that is tracer-free. 2012 John Wiley Sons, Ltd. |
| 出处 | Hydrological Processes
 |
| 卷 | 26期:23页:3614-3629 |
| 收录类别 | EI |
| 语种 | 英语 |
| 源URL | [http://ir.igsnrr.ac.cn/handle/311030/27623]  |
| 专题 | 地理科学与资源研究所_历年回溯文献 |
| 推荐引用方式 GB/T 7714 | Han D. M.,Song X. F.,Currell Matthew J.,et al. Using chlorofluorocarbons (CFCs) and tritium to improve conceptual model of groundwater flow in the South Coast Aquifers of Laizhou Bay, China. 2012. |
入库方式： OAI收割
来源：地理科学与资源研究所
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