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为考察土壤锰氧化物的还原溶解行为，本文选取常见的根系分泌的8种有机酸（抗坏血酸、香草酸、柠檬酸、草酸、酒石酸、水杨酸、半胱氨酸和邻苯二甲酸）和1种酚类化合物（邻苯二酚），人工合成的MnO2和5种富含氧化锰的土壤（广东徐闻的砖红壤、海南澄迈的砖红壤、云南昆明的砖红壤、浙江嵊县的红壤和江苏南京的黄棕壤），研究了有机化合物对氧化锰的还原溶解作用．结果表明，较低pH和较高温度有利于有机化合物对MnO2的还原溶解．在pH 4．5—5．5和温度5—45℃范围内，不同有机化合物还原溶解MnO2能力的大小顺序为：邻苯二酚＞半胱氨酸＞抗坏血酸＞香草酸＞柠檬酸＞草酸≈酒石酸＞水杨酸≈邻苯二甲酸．邻苯二酚、半胱氨酸和抗坏血酸对土壤中氧化锰也有较强的还原溶解能力．当5种土壤比较时，徐闻砖红壤中还原溶解出的锰量最高，其次为昆明砖红壤，嵊县红壤中还原溶解出的锰量最小．当有还原性有机化合物存在时徐闻砖红壤、昆明砖红壤和澄迈砖红壤中的氧化锰容易发生还原溶解反应，增加土壤中可溶态和交换态Mn2＋的含量，并可能对植物产生锰毒害．

In order to get an insight into the reductive dissolution behaviors of manganese oxides in soils, eight organic acids ( cysteine, ascorbic acid, vanillic acid, citric acid, oxalate acid, tartaric acid, salicylic acid and phthalic acid) and one phenolic compound (catechol), synthetic MnO2, and five types of high?manganese oxides?containing soils ( three latosols from Xuwen of Guangdong Province, Chengmai of Hainan Province and Kunming of Yunnan province, respectively, one red soil from Shengxian of Zhejiang Province and one yellow?brown soil from Nanjing of Jiangsu Province) were used to investigate the reductive dissolution of manganese oxides by these organic compounds. The results showed that low pH and high temperature favoured the reductive dissolution of MnO2 by the organic compounds. In the range of pH 4. 5—5. 5 and 5—45 ℃, the reductive dissolution of MnO2 by the organic compounds followed the order: catechol > cysteine > ascorbic acid > vanillic acid > citric acid > oxalate acid ≈ tartaric acid > salicylic acid ≈ phthalic acid. Catechol, cysteine and ascorbic acid showed stronger ability to reduce and dissolve MnO2 . Among the five soils, the highest amount of Mn2+ was reductively dissolved from the latosol from Xuwen, followed by the latosol of Kunming, and the least amount of Mn2+was reductively dissolved from the red soil from Shengxian. The results presented in this study suggest that the manganese oxides in the latosols from Xuwen, Kunming and Chengmai were easy to be reduced by reducing organic compounds, which increased the contents of soluble and exchangeable Mn2+in these soils and could cause manganese toxicity to plants in the soils.