蓮華池兩森林土壤之硫酸吸附現象

Sulfate Sorption by Two Forest Soils in the Lien-Hua-Chi Area

金恒鑣(Hen-Biau King) ； 康敏捷(Min-Chieh Kang) ； 王明光(Ming-Kuang Wang)

《林業試驗所研究報告季刊》 10卷1期 (1995/03) Pp. 65-74

https://doi.org/10.7075/BTFRI.199503.0065

摘要

本研究以蓮華池地區的極育土與弱育土來模擬酸雨（變動pH和SO4濃度）造成的硫酸根吸附與脫附現象。由結果顯示，兩種土壤之吸附性硫酸根（以Na2HPO4溶液抽出）的含量(0.3mmol/kg-1.09mmol/kg)都比水溶性硫酸根含量(0.15mmol/kg-0.41mmol/kg)多。其中弱育土之原有硫酸根含量比極育土來的多。兩土壤之硫酸根吸附，受到其含游離氧化鐵、鋁量影響。其中尤其以土壤原有吸附的硫酸根含量，與醋酸銨抽出的可交換性鋁，達到顯著水準相關(r=0.77)。兩類森林土壤的（水溶性+Na2HPO4可溶性）原有硫酸根含量，均已接近該土壤之最大吸附量，此顯示蓮華池森林土壤對硫酸根的吸附，已快達飽和。由批次試驗得知，兩土壤的硫酸根吸附量與鋁之釋放，隨平衡溶液的pH值降低而增加。蓮華池森林土壤對H(上標 +)的緩衝作用，主要機制有三：陽離子的交換、硫酸根的吸附及黏土邊緣的鋁和鋁氧化物的溶解。三種緩衝機制的重要性，受到pH值不同而異。當酸度較高的酸雨進入到土壤時，土壤對H(上標 +)的緩衝作用最小，主要機制為黏土邊緣的鋁(A1-site)和鋁氧化物的溶解。而酸度較低的酸雨進入土壤，其主要的緩衝因子為陽離子的交換和硫酸根的吸附。

關鍵字

森林土壤 ； 硫酸根 ； 吸附

並列摘要

Two forest soil pedons, Dystrochrept and hapludult, of Lien-hua-chi watershed in the central Taiwan were selected to investigate their sulfate adsorption and desorption of the soils. Samples from major soil horizons were leached with simulated acid solution varying in levels of acidity and sulfate.
The results showed that the amount of native adsorbed sulfate of two soils, as extracted with Na2HPO4, ranged from 0.30 to 1.09 mmol/kg, was greater than native water soluble sulfate, as extracted with H2O, ranged from 0.15 to 0.41 mmol/kg. The native sulfate content of Dystrochrept soils were greater than Hapludult soils.
The native sulfate content of two soils correlated insignificantly with sesquoxide content and significantly with exchangedable Al content (r=0.77), which was extracted by ammonium-acetate solution.
The native sulfate content, for all tested soil samples were colse to their maxiumn sulfate adsorption capacity. This capacity and the amount of Al released increased with increasing acidity of added simulated rain solution.
The dominant mechainisms that controlled the buffering capcity of the tested soils against hydrogen ions varied with the acidty of added rain solution. When the acidity of added solution was low the buffering acpacity was controlled by the cation exchangedable capacity and slufate adsorption capacity of the soils. At high acidity the buffering capacity was controlled by the Al which located at the broken edges of clay minerals as well as Al-oxides.

並列關鍵字

Forest soils ； sulfate ； sorption