北京地区石灰性土壤对锰的吸附

DSORPTION OF MANGANESE ONCALCAREOUS SOILS IN BEIJING

本文研究了北京地区４种类型５个石灰性土壤样品对锰的吸附、及其与土壤各理化性质的关系。在每克土壤加入２５ｍｌ１０～２００ｇＭｎ／ｍｌ的剂量范围内，土壤对锰的吸附极好的遵从Ｆｒｅｕｎｄｒｉｃｈ等温方程，而是否符合Ｌａｎｇｍｕｉｒ等温方程则与加入的锰溶液浓度有关，当其小于１２０ ｇＭｎ／ｍｌ时，则能较好地符合Ｌａｎｇｍｕｉｒ方程；这一现象说明，土壤具有两种或两种以上的吸附位。在土壤各理化性质中主要是粘粒含量和阳离于交换总量（ＣＥＣ）影响到锰的吸附。但在锰溶液浓度较低时，各土壤理化性质均与土壤吸附锰量无显著相关。平衡溶液的ｐＨ强烈影响土壤吸附锰的能力，当ｐＨ由４上升至７左右时，土壤对锰的吸附急剧增加，ｐＨ值再上升，土壤吸附锰量的增加趋于平缓。

Five soils samples at 0￣25 cm depth were equilibrated with Mn solutions to test theconformity to the Langmuir and Freundlich isotherms and to relate the manganese adsorp-tion data to soil properties. The data conformed to Freundlich isotherm over entire Mn con-centration range tested (10 to 200 g/ml). When the data were plotted according to the con-ventional Langmuir equation , the isotherms were linear only at lower Mn concentrations(<120 g/ml) . indicating that more than one population of adsorption sites existed in thesesoils. No significant correfation has been found between and soil Properties when the addedMn was lower than 2000 g/gsoil. Mn adsorption equilibrated with higher Mn concentrationsolutions(> 80 ￣ 200 g/ml)were highly correlated with the cation exchange capacity(CEC)and clay content ,but not with values of organic matter content,calcium carbonate equiva-lent , or soil PH.H study of the effect of equilibrium solution PH on adsorption showed thatMn adsorption was significantly increased when the PH value increased from 4 to 7.