Abstract:
By simulating dry-hot, wet-hot and dry-cool climate respectively and taking water saturated with CO2 as leaching solution, a leaching experiment is carried out(of them, leaching experiment simulating dry hot and wet-hot climate reached acid-insoluble residue stage) on rock powder layer samples from rock-soilinterfacein3 weathering profiles in central Guizhou karst region. The results indicate that acid-insoluble residues have shown significant weathering tendency along with carbonate dissolution at rock-soil interface of weathering profiles. In three kinds of different leaching conditions, the dissolution intensity of carbonate displays the trend of dry-cool> dry-hot> wet-hot. When the temperature slow, the dissolution rate of carbonate is high, and as the drainage condition is good, Ca and Mg released by carbonate dissolution are easy to be discharged from the system. Concerning the acid-insoluble residues in carbonate rocks, firstly, the weathering intensity of carrier minerals of K, Na, Mg, Si and P is the strongest in dry-hot condition(as for Ca, for both calcite and dolomite are its major carrier minerals in carbonate rocks, it is different to effectively identify Ca deriving from acid-insoluble phase in leaching solution).Between dry-cool and wet-hot, the release ability of K, Na and Mg, i.e. base cations, from the system, in most cases, is for wet-hot> dry-cool, and it is indicated that the temperature severely constrains the release strength of base cations; the release ability of Si and P is not demonstrated a consistent trend in three samples, and it may be caused by the differences in microenvironment of the leaching system. Secondly, Fe and M n are weak migration elements. A among them, the leaching intensity of Fe in dry-cool condition is the weakest, and it indicates that the temperature is an important factor to constrain the decomposition rate of Fe-containing minerals. While leaching intensity of Fe between dry-hot and wet-hot and M n among three kinds of different leaching conditions, do not show a consistent trend in three samples. Thirdly, Al and Ti show strong inertness during weathering of carbonate rocks.
