College of Resources and Environmental Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
Sci Total Environ. 2022 Sep 10;838(Pt 4):156436. doi: 10.1016/j.scitotenv.2022.156436. Epub 2022 Jun 3.
The mining of medium- to high‑sulfur coal in karst areas has led to serious acidification problems in surface water, thus encouraging a re-evaluation of DIC transformation and CO source-sink relationships in karst watersheds. The weathering of limestone and sulfide-rich coal measures jointly influence the pH of the Huatan River in karst areas in Southwest China, which is lower in the rainy season and higher in the dry season. Due to CO degassing, DIC concentration tends to decrease along the flow direction, while δC-DIC gradually becomes heavier. In general, DIC transformation in the Huatan River is controlled by AMD input, CO degassing, organic matter (OM) degradation, and the dissolution and precipitation balance of carbonate minerals in different seasons. In spring, the mineralization of OM from terrestrial and domestic sewage gradually enhances and replenishes DIC in the water. As the pH increases in this season, the capacity for buffering CO increases. Meanwhile, OM degradation generates a large amount of CO in summer, and carbonic acid begins to dissolve limestone. In autumn, the pH decreases due to the enhanced weathering of sulfide-rich coal measures and the mass input of AMD. Thus, the river shows the ability to drive CO outgassing. In winter, CO degassing gradually weakens, DIC concentration is at its lowest, and δC-DIC reaches the heaviest value.
在岩溶地区开采中高硫煤导致地表水严重酸化，这促使人们重新评估岩溶流域中 DIC 的转化和 CO 的源汇关系。石灰岩和富硫煤系的风化共同影响了中国西南岩溶地区花滩河的 pH 值，雨季较低，旱季较高。由于 CO 的脱气作用，DIC 浓度沿水流方向呈下降趋势，而 δC-DIC 逐渐变重。总的来说，花滩河的 DIC 转化受 AMD 输入、CO 脱气、有机物（OM）降解以及不同季节碳酸盐矿物溶解和沉淀平衡的控制。在春季，陆地和生活污水中的 OM 矿化逐渐增强，并补充水中的 DIC。随着本季 pH 值的升高，缓冲 CO 的能力增强。同时，夏季 OM 降解产生大量 CO，碳酸开始溶解石灰岩。秋季，由于富硫煤系风化加剧和 AMD 的大量输入，pH 值下降，河流表现出驱动 CO 脱气的能力。在冬季，CO 脱气逐渐减弱，DIC 浓度达到最低，δC-DIC 达到最重的值。
