Resumen de Distribution characteristics of chemicals and heavy metals in typical karst subterranean rivers in South China
Shuyi Liu, Chuan Liang, Lichao Yang, Jianghua Long, Nan Jing, Ruixiang Yang, Xin Liu
The goal of this study is to understand the impact of human activities on the characteristics of chemicals and heavy metals in typical karst subterranean rivers in South China and the patterns of their changes. Thus, the Jila, subterranean river in Liuzhou, the Lihu subterranean river in Nandan and the Maocun village subterranean river in Guilin in karst regions in Guangxi Province and the Banzhai subterranean river in Maolan in a karst region in Guizhou Province were selected for analysis. These four rivers are typical subterranean rivers and are affected by human activities to different extents. During October–December 2015 (dry season), we performed on-site investigations and collected water samples. The results show the following: (1) Ca2+ and HCO3− are significantly correlated with the heavy metals Cr and Ni in the four subterranean rivers (p < 0.01); this relationship is mainly attributed to rock weathering from dissolution but is caused mostly by human activities. (2) The detected concentrations of K+, Na+, NH4+, Cl− and SO42− are significantly correlated with the detected concentrations of NO3− in the four subterranean rivers (p < 0.01); domestic sewage, pesticides and fertilizer are the main sources. (3) The dilution from precipitation results in decreases in the ion concentrations, but the NO3− and SO42− concentrations following dilution from precipitation are still high, suggesting that domestic sewage and the application of fertilizer continuously impact the subterranean rivers. (4) Conductivity is an important index that reflects the status of land usage and water quality; the conductivity levels increase with anthropogenic disturbances. (5) The comparison of previously published ion concentrations in the Jila subterranean river in Liuzhou with those measured in this study shows that pollution has decreased substantially, which is closely related to urban planning and enhanced environmental consciousness in this region. The above results and conclusions can provide a scientific basis for the optimal management of water resources in the karst regions in South China and the improvement of water quality for subterranean rivers.
