Aggtelek National Park, Hungary, is a limestone karst upland characterized by karren, dolines and river caves. For a period of two years, climatic and carbonate dissolution variables were monitored at four depths in a 7·5 m shaft through the soil fill in the floor of a typical large (150 m diameter) doline. Results are compared to other monitoring stations in shallow soils on side slopes. Runoff and groundwater flow are focused into the base of the doline soil fill, where moisture is maintained at 70-90 per cent field capacity and temperatures permit year-round production of soil CO 2 . The capacity to dissolve calcite (limestone) ranges from c.3g m −2 per year beneath thin soils on the driest slopes to 17-30 g m −2 per year in the top 1-2 m of doline fill and at its base 5-7 m below.
The acids accumulating in soils and controlling the solution of carbonates including the predominant CO 2 , mostly derive from three processes: ⅰ) root respiration of higher plants; ⅱ) decomposition of soil organic matter by microorganisms (microbiota) and ⅲ) other decomposition processes not associated with microbial activities. The solution effect under rendzina soils is primarily used for the dissolution of the enclosed limestone fragments and thus here the solution of bedrock is of limited scale. Below karst soils of high clay content the corrosion of bedrock is more intensive than under rendzinas. On the whole, the amount of carbonates dissolved and transported into the depths of the karst is smaller than below rendzinas. In each soil type studied the solution caused by microbial activities manifold exceeds the rate of solution resulting from temperature factor but there is a manifest dropping trend from rendzina to clays.Among the acids produced in soils CO 2 , fundamental in hydrocarbonate solution, seems to be of decisive Significance [1] . There is a broad agreement among researchers that the acids accumulating in soils [2][3][4][5] and controlling the solution of carbonates, including the predominant O 2 , mostly derive from three groups of processes [6][7][8][9] : 1) Root respiration of higher plants [10][11][12][13][14][15][16] ; 2) decomposition of soil organic matter by microorganisms (microbiota) [17][18][19][20][21][22][23] ; and3) other decomposition processes not associated with microbial activities [24] .There are only sporadic estimates in literature on the share of the above processes (CO 2 sources) in karst corrosion and an equal distribution (1:1:1) is generally suggested.Investigating carbonate solution in soils and attempting to obtain more precise data, 96 corrosion models of identical composition, which are suitable for estimating corrosion below the soil layer, have been constructed. (ⅰ) A glass tube of 40 mm in diameter was used to enclose the sample, a 9 cm deep column of undisturbed structure, which is characteristic of mid-latitude open karsts; (ⅱ) at the upper end the model is plugged by a bacterium filter, which does not hinder aeration; through this filter bacteria-free water recharge modelling rainfall can be ensured; (ⅲ) below the solum 1 cm 3 volume, easily soluble limestone cubes, seven for each model represent the rock affected by corrosion; the cubes are placed between two, chemically inactive, plastic filters. The investigations show that the corroding effect originated in the soil is entirely manifested and the soil solution percolating through becomes saturated; (ⅳ) at the bottom end the model is closed down by a rubber plug and the solution percolating through it is gathered by a sterile plastic bag.The objective of the investigation was to allow the comparison of solution effect by absorbing the entire carbonate solution capacity originating in the soil. Limestone solution capacity is expressed by the concentration of dissolved carbonate (milligrams) or by the equival...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.