CARBONIC-ACID LEACHING IN A TROPICAL, TEMPERATE, SUBALPINE, AND NORTHERN FOREST SOIL

The role of carbonic acid as a soil cation leaching agent was found to decrease as annual temperature decreased among 4 sites ranging from tropical rainforest to subalpine and northern forest. Carbonic acid dissociation was suppressed by low pH in the subalpine and northern soil solutions, and the presence of organic acids is suspected in these solutions. The presence of the bicarbonate anion has a major impact on yearly cation transport through a soil. The reduced bicarbonate concentrations at low pH in the subalpine and northern sites reduced nutrient loss from the rooting zone. The roles of sulfate and chloride in the anion component of soil solutions are also discussed with reference to sources of SO2 and sea salt and the cycling of S and Cl.