Environmental isotopic and hydrochemical characteristics of groundwater systems in Daying and Qicun geothermal fields, Xinzhou Basin, Shanxi, China

Abstract

Abstract:The conceptual hydrogeological model of the low to medium temperature Daying and Qicun geothermal fields has been proposed, based on hydrochemical characteristics and isotopic compositions. The two geothermal fields are located in the Xinzhou basin of Shanxi, China and exhibit similarities in their broad-scale flow patterns. Geothermal water is derived from the regional groundwater flow system of the basin and is characterized by ClÐSO 4 -Na type. Thermal water is hydrochemically distinct from cold groundwater having higher total dissolved solids (TDS) (>0Ð8 g/l) and Sr contents, but relatively low Ca, Mg and HCO 3 contents. Most shallow groundwater belongs to local flow systems which are subject to evaporation and mixing with irrigation returns. The groundwater residence times estimated by tritium and 14 C activities indicate that deep non-thermal groundwater (130-160 m) in the Daying region range from modern (post-1950s) in the piedmont area to more than 9Ð4 ka BP (Before Present) in the downriver area and imply that this water belong to an intermediate flow system. Thermal water in the two geothermal fields contains no detectable active 14 C, indicating long residence times (>50 ka), consistent with this water being part of a large regional flow system. The mean recharge elevation estimated by using the obtained relationship Altitude (m) D 23Ð8 ð υ 2 H (‰) 121Ð3, is 1980 and 1880 m for the Daying and Qicun geothermal fields, respectively. The annual infiltration rates in the Daying and Qicun geothermal fields can be estimated to be 9029 ð 10 3 and 4107 ð 10 3 m 3 /a, respectively. The variable 86 Sr/ 87 Sr values in the thermal and non-thermal groundwater in the two fields reflect different lithologies encountered along the flow path(s) and possibly different extents of water-rock interaction. Based on the analysis of groundwater flow systems in the two geothermal fields, hydrogeochemical inverse modelling was performed to indicate the possible water-rock interaction processes that occur under different scenarios.

Sustainability of groundwater usage in northern China: dependence on palaeowaters and effects on water quality, quantity and ecosystem health

“…Palaeowaters are groundwater resources that were recharged in premodern times, under different climatic or hydrological regimes than the present (Clark and Fritz, 1997). In the last 5 to 10 years, several studies have shown that deep sedimentary aquifers throughout northern China (mostly semiconfined or confined aquifers) contain groundwater recharged during the Late Pleistocene and Early Holocene periods (Chen et al, 2003;Edmunds et al, 2006;Gates et al, 2008a;Kreuzer et al, 2009;Ma et al, 2009aMa et al, , 2009bCurrell et al, 2010;Han et al, 2010a;Ma et al, 2010;Chen et al, 2011). Palaeowaters, identified by radiocarbon dating, stable isotope analysis and (in some cases) measurement of noble gases, are exploited at high rates throughout northern China, mostly to provide water for irrigation (Ma et al, 2005;Edmunds et al, 2006;Kreuzer et al, 2009;Chen et al, 2010;Currell et al, 2010;O'Dochartaigh et al, 2010).…”

“…Elevated fluoride and arsenic concentrations. Elevated fluoride and arsenic concentrations in groundwater are widespread in northern China, particularly in shallow aquifers, and also in some deep, regional aquifer units (Smedley et al, 2003;Gao et al, 2007;Guo et al, 2007a;Guo et al, 2007b;Yu et al, 2007;Mukherjee et al, 2009;He et al, 2010;Han et al, 2010a;Currell et al, 2011). This has been identified as one of the major issues affecting water quality in arid and semiarid regions globally (United Nations, 2006).…”

Hydrogeochemical characterization of groundwater flow systems in the discharge area of a river basin

“…Even if lithology is similar, the travel distance and travel time determine the degree of water-rock interaction, thus the geochemical composition. Therefore, hydrochemistry provides an excellent indicator to identify the sources of groundwater from different aquifers (Adomako et al, 2011;Barth, 2000;Cloutier et al, 2008;Currell et al, 2010;Demlie et al, 2007;Edmunds et al, 1982;Elliot et al, 1999;Fagundo-Castillo et al, 2008;Han et al, 2010;Kimblin, 1995;Montcoudiol et al, 2014;Portugal et al, 2005;Zhu et al, 2007) or the flow path from a recharge area to its corresponding discharge area (Adomako et al, 2011;Aji et al, 2008;Alconada-Magliano et al, 2011;Cartwright et al, 2004;Chen et al, 2004;Edmunds et al, 2006;Han et al, 2009;Herczeg et al, 1991;Mahlknecht et al, 2006;Montcoudiol et al, 2014).…”

Multiple-indicator study of groundwater flow and chemistry and the impacts of river and paddy water on groundwater in the alluvial fan of the Tedori River, Japan

“…Because older rocks have higher 87 Sr/ 86 Sr ratios than younger rocks with the same initial Rb/Sr ratio, the 87 Sr/ 86 Sr ratio in rocks with a high Rb/Sr ratio becomes higher than that of rocks with a lower Rb/Sr ratio. Thus, the 87 Sr/ 86 Sr ratio in water is an indicator of both age and geochemical origin (Capo et al, 1998); this ratio has been used successfully to distinguish different sources of groundwater recharge and to identify likely flow paths (Yamanaka et al, 2005;Petelet-Giraud et al, 2007;Uliana et al, 2007;Han et al, 2010;Banks et al, 2011;Xie et al, 2013). 87 Sr/ 86 Sr ratios have also been used to assess the impacts of agricultural activities on groundwater (Böhlke and Horan, 2000;Hosono et al, 2007;Nakano et al, 2008;Jiang, 2011).…”