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	Recharge history and controls on groundwater quality in the Yuncheng Basin, north China
	Currell M. J. ; Cartwright I. ; Bradley D. C. ; Han D. M.
	2010
关键词	Groundwater Sustainability Environmental isotopes China Nitrate Palaeowaters loess plateau nitrate contamination murray basin minqin basin plain variability isotopes monsoon oxygen water
英文摘要	Environmental isotopes and water quality indicators (e.g. TDS and NO(3) contents) were used to characterize the age, recharge history and controls on the quality of groundwater resources in the Yuncheng Basin, north China, where extensive extraction occurs for agriculture and domestic supply. delta(18)O and delta(2)H values as low as -10.6%. and -73 parts per thousand, respectively, together with low radiocarbon activities (<20 pmC) show that deep groundwater comprises palaeowaters largely recharged in the late Pleistocene (similar to 10 to 22 ka B.P.) under a cooler climate than the present. Shallow groundwater has higher radiocarbon activities (>70 pmC), indicating a significant component of modern (post-1950s) recharge. The shallow groundwater has higher delta(18)O and delta(2)H values (up to -8.1%. and -54 parts per thousand) that are similar to those in modern summer monsoon rainfall, indicating that current recharge is via direct infiltration and/or leakage of ephemeral streams during heavy rain events. Historic recharge rates estimated using radiocarbon ages are between 1 and 10 mm/year, corresponding to <2% of local rainfall, which is lower than estimates of modern recharge nearby based on tritium data. The relationship between groundwater delta(18)O values and (14)C ages is similar to that observed in groundwater from other basins in northern China, confirming that much deep groundwater in the region is palaeowater, and suggesting that a broad scale assessment of groundwater residence times may be made from delta(18)O and delta(2)H values. Most deep groundwater has low TDS and nitrate concentrations (median 1090 mg/L and 1.8 mg/L, respectively), while shallow groundwater has TDS contents of up to 8450 mg/L (median 2010 mg/L) and NO(3) concentrations up to 630 mg/L (median 31 mg/L). A lack of enrichment in delta(18)O values in the high salinity shallow groundwater indicates that transpiration by crops and possibly minor mineral dissolution are the major salinisation processes, rather than evaporation or leakage from salt lakes. The majority of nitrate in groundwater has delta(15)N (NO3) values between 0.8 parts per thousand and 5.0 parts per thousand and delta(18)O(NO3) values between 1.8 parts per thousand and 4.1 parts per thousand, indicating that synthetic fertilizers are the main source of elevated NO(3) concentrations. Increasing residence times from east-to-west in deep groundwaters reflect the historic regional flow pattern in the basin. However, present-day flow is now dictated by a large cone of depression that has formed due to intensive deep groundwater pumping since the 1980s. High downward vertical hydraulic gradients (up to 0.45) have also developed as a result of this pumping, promoting downwards leakage of shallow water, indicated by high nitrate concentrations (>20 mg/L) in some deep wells (>180 m). Preferential leakage has occurred near the Linyi fault, in the northern Sushui River Basin. Salinisation, nitrate contamination and excessive drawdown of deep groundwater are major concerns for the future of the groundwater resources in this region. (C) 2010 Elsevier B.V. All rights reserved.
出处	Journal of Hydrology
卷	385
期	1-4
页	216-229
收录类别	SCI
语种	英语
ISSN号	0022-1694
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/24175]
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	Currell M. J.,Cartwright I.,Bradley D. C.,et al. Recharge history and controls on groundwater quality in the Yuncheng Basin, north China. 2010.

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