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Effects of Sulfur Compounds and Other Air Pollutants on Soil and Groundwater

出版	National Swedish Environmental Protection Board, 1985
ISBN	91620300279789162030025
URL	http://books.google.com.hk/books?id=7QdIAAAAYAAJ&hl=&source=gbs_api

註釋This report is a condensed literature survey of published material on the acidification of soil and groundwater. Three criteria describe soil acidification, viz. a decrease of exchangeable base cations, an increase of the aluminum concentration in the soil solution, and a pH decline over time. The degradation of soils due to acid deposition follows a pattern in three steps: (1) the excess load of hydrogen ions increases the weathering rate of soil minerals, keeping the pH almost constant. (2) the leaching losses of Mg, K and certain trace elements increase and cause nutrient deficiency in the soil, the soil pH decreases gradually and the solubility of toxic metals increases, (3) the primary forest productivity decreases and plant damages occur. Step 2 is reached in large parts of central and northern Europe as far as forest soils are concerned. Step 3 is reached in parts of central and southern Sweden. However, there is no general agreement as to the factors causing the deterioration. Concerning groundwater it is stated that a number of inventories report the occurrence of acid groundwater in various aquifers. Also corrosion is mentioned. Changes with time during the last decades have been observed in a small number of reported cases, e.g. as decreasing pH and alkalinity, and increasing content of Ca and Mg in the groundwater, particularly in sensitive, shallow systems Apart from acid deposition also biogeochemical processes, changed land use and pumping, and groundwater recharge conditions are referred to for the explanation of the observed changes.