Wang Jian-li

Characteristics and environmental significance of Ca, Mg, and Sr in the soil infiltrating water overlying the Furong Cave, Chongqing, China

This paper explores the influence of the local meteoric conditions, the overlying soil on the concentrations of Ca, Mg, and Sr, and the ratios of Mg/Ca, Sr/Ca, and Mg/Sr in soil infiltrating water (SIW). An in situ monitoring program was carried out above the Furong Cave throughout 2010 to collect data on SIW, monthly temperature and rainfall, and the geochemical composition and granularity of soils. The discharge of SIW responded quickly to the local rainfall, and its residence time was the primary factor affecting the Ca, Mg, and Sr content of the SIW. The high concentrations of Ca, Mg, and Sr in the SIW during April should be attributed primarily to the prolonged residence of SIW in the soil during the local dry seasons of winter and early spring. The maximum Mg/Sr ratio also occurred in April. The ratio of Mg/Ca in SIW is positively correlated with prolonged residence time and with high temperatures, which do not strongly affect the ratio of Sr/Ca. The Mg/Ca ratio was lowest when the Sr/Ca ratio was highest because plant metabolism increased the absorption of Ca and Mg, but not Sr, and also because higher temperatures enhanced the dissolution of Mg more than that of Sr. These different responses of Mg and Sr to temperature increases resulted in high Mg/Sr ratios during July and August.