不同岩性试片溶蚀速率差异及意义

评价岩性对溶蚀速率的影响有助于提高岩溶碳汇强度估算精度,对当前全球气候变化研究意义重大。本文通过在山西晋中盆地西南,吕梁山东侧的半干旱岩溶区典型小流域开展标准试片与当地试片的对比溶蚀试验研究,结果显示当地试片的溶蚀速率(0.122 3~0.532 8mg/(cm2·a)和岩溶碳汇强度(1.713tCO2/(km2·a))明显小于标准试片(0.254 7~0.551 1mg/(cm2·a)和1.821tCO2/(km2·a)),表明使用标准溶蚀试片法会使岩溶碳汇强度被高估。当地试片的溶蚀速率与酸不溶物含量呈负相关关系,进一步表明当地试片酸不溶物含量(2.58%~10.86%)大于标准试片(3%)是造成其溶蚀速率和岩溶碳汇强度小于标准试片的重要原因。也就是说,由于埋放地地层岩性与标准溶蚀试片岩性特征存在差异,不同地区均采用埋放标准试片的溶蚀实验方法来研究岩溶碳汇效应会产生较大的误差。因此,为了更加精确的计算岩溶碳汇量,后期研究中有必要使用埋放地的岩性试片来替代标准溶蚀试片。

Dissolution Rate and It's Significance of Different Lithological Tablets

Influence of lithology on dissolution rate is helpful to estimate karst carbon sink intensity, which is of great significance to the research on global climate change. Comparative dissolution experiment with standard tablets and local tablets was carried out in a typical small watershed in semi-arid area, southwest of the Jinzhong Basin, Shangxi Province, China. Results show that the dissolution rate (0.122 3-0.532 8 mg/(cm²·a)) and karst carbon sink intensity (1.713 tCO₂/(km²·a) of local rock tablets are significantly lower than those of standard rock tablets (0.254 7-0.551 1 mg/(cm²·a) and 1.815 tCO₂/(km²·a)), respectively. This means that the karst carbon sink intensity is overrated by standard rock tablets method. The negative correlation between tablets dissolution rate and contents of acid insoluble further indicates that higher levels of acid insoluble content of local tablets (2.58%-10.86%)than those of the standard tablets (3%) are the major cause for the lower dissolution rate and karst carbon sink intensity. In other words, since there are differences characteristics of formation lithology between local tablets and standard tablets, great error will be produced by using standard tablets to study karst carbon sink effect of different regions. Therefore, in order to accurately calculate the amount of karst carbon sink, it is necessary to use local rock tablets instead of the standard tablets.