【作者】 廖丽霞；

【导师】 贺纪正； 胡红青；

【作者基本信息】 华中农业大学 ， 环境工程， 2001， 硕士

【摘要】 本文以黄褐土、黄棕壤、棕红壤、红壤和砖红壤五种地带性土壤为材料，在测试其基本性状、粘土矿物组成、表面电荷性质的基础上，研究了有机酸（乙酸、草酸、酒石酸、柠檬酸）对土壤表面电荷性质和Cd²⁺次级吸附的影响，取得的主要研究结果如下： 1)供试土壤的负电荷量随体系的pH升高而增加，正电荷量随体系的pH升高而降低。在同一pH条件下，土壤负电荷量由北向南呈递减趋势，正电荷量呈递增趋势。在砖红壤中，负电荷以可变负电荷为主；棕红壤和红壤既有较大数量的可变负电荷，又含有一定数量的永久负电荷；黄褐土和黄棕壤负电荷量随pH的变化较小。供试砖红壤的PZNC为4.2，其它土壤在实验pH范围内不存在PZNC。供试土壤的PZC从北到南逐渐升高。 2)黄棕壤和黄褐土对酒石酸的等温吸附曲线属H型—高亲和力型。黄棕壤对酒石酸的吸附量小于黄褐土。红壤对草酸的等温吸附曲线属H型—高亲和力型；黄棕壤和棕红壤对草酸的吸附曲线属L型—低亲和力型；砖红壤对草酸的吸附曲线属C型—低亲和力型。由Langmuir方程计算出土壤对草酸的最大吸附量顺序为，砖红壤（54.39 mmol/kg）＞黄棕壤（27.11mmol/kg）＞棕红壤（18.81 mmol/kg）＞红壤（11.48 mmol/kg）。 3)黄褐土和黄棕壤吸附有机酸后，负电荷量降低，正电荷量变化不明显，PZC升高。不同有机酸对恒电荷土壤电荷量的影响大小顺序为：草酸＞酒石酸＞乙酸≥柠檬酸。砖红壤、棕红壤和红壤吸附有机酸后，负电荷量升高，正电荷量降低，PZC降低，其中砖红壤PNZC向酸侧移动约0.3个pH。不同有机酸对可变电荷土壤电荷量的影响大小顺序大致为：柠檬酸＞酒石酸≥草酸＞乙酸。高浓度有机酸对土壤PZC的影响强于低浓度的。 4)供试五种土壤对Cd²⁺的等温吸附曲线用Langmuir方程拟合达极显著水平（R²＞0.95）。其最大吸附量从高到低依次为黄褐土（1146mg/kg）＞棕红壤（611.6 mg/kg）>黄棕壤（593.9 mg/kg）＞砖红壤（463.6 mg/kg）＞红壤（453.8 mg/kg）。土壤吸附草酸和柠檬酸后，对Cd²⁺的次级吸附量明显升高且显著降低了土壤对Cd²⁺的吸附结合能，从而增强了土壤对Cd²⁺的有机酸对土堆表面电荷性质和Cd2+次级吸附的影晌吸附亲和力，使得土壤吸附有机酸后，次级吸附Cd卜等温曲线从L型向H型转变。同时有机酸的吸附使得土壤对CdZ+的吸附曲线的斜率增大，意味着土壤吸附有机配体后，对Cd2+缓冲容量增大。更多还原

【Abstract】 The basic properties, clay mineral association and surface charge properties for zonal soils in china, including yellow cinnamon soil, yellow brown soil, brown red soil, red soil and latosol, were investigated. The effects of organic acids (acetic acid, oxalic acid, citric acid, tartaric acid) on surface charge properties and second adsorption of cadmium for different soils were also studied. The main results were shown as follows:1. The organic matter content of the examined soils followed the Series: latosol (43.5g/kg)>red soil(26.7g/kg)>brown red soil(17.3g/kg)>yellow brown soil(16.7g/kg) > yellow cinnamon soil(9.6g/kg). The clay content of yellow brown soil (320g/kg) was the lowest, and that of latosol(780g/kg) was the highest. For the clay association, the prominent clay mineral in yellow cinnamon soil and yellow brown soil was hydromica(75~80%), whereas the main clay mineral in latosol was kaolinite(95%).From north to south, the expansive minerals changed regularly from montmorillonite to vermiculite, then to 1.4nm integrade mineral. Gibbsite was present in latosol. The Fe and Al content extracted by DCB solution tends to increase from yellow cinnamon soil to latosol.2. The amount of negative charge increased with the increasing of pH value, while that of the positive charge decreased. At the same pH value, the negative charge of the examined soils tended to decrease from north to south, whereas the positive charge increased. The latosol bore variable negative charge as predominant charge, and the brown red soil and red soil bore not only somevariable negative charge, but also some permanent negative charge. The negative charge was not significantly pH-dependent in yellow cinnamon soil and yellow brown soil. The magnitude of PZNC for the latosol is 4.2, but that for other soils was not detectable in the experimental pH range. The magnitude of PZC tended to increase from yellow cinnamon soil to latosol.3. Isotherms for adsorption of tartaric acid on yellow cinnamon soil and yellow brown soil belonged to "H type", which was called as high affinity type. With the content of tartaric acid in solution increasing from 0 to 4.8mmol/L, the sorption capacity on yellow brown soil was lower than that on yellow cinnamon soil. Isotherms for adsorption of oxalate on red soil also belonged to "H type", and that on yellow brown soil and brown red soil belong to "L type", which was behalf of low affinity type. The adsorption of oxalate on latosol belonged to "C type", which was behalf of high affinity type. According to the Langmuir equation, the maximum sorption capacity of oxalate on soils was: latosol (54.39mmol/kg) > yellow brown soil (27.11mmo/kg) > brown red soil (18.81mmol/kg) > red soil (11.48mmol/kg).4. After yellow cinnamon soil and yellow brown soil adsorbed organic acids, their negative charge quantities decreased if compared to that of original soils , and the positive charge changed slightly, whereas the magnitude of PZC increased. The effects of different organic acids on surface charge of permanent charge soil in order was: oxalic acid > tartaric acid > acetic acid > citric acid. After brown red soil, red soil and latosol adsorbed organic acids, their negative charge increased if compared to that of original soils, whereas the positive charge and the magnitude of PZC decreased. The magnitude of PZNC for latosol decreased about 0.3 pH compared to that of original soil. The effects of different organic acids on surface charge of variable charge soil in order was: citric acid > tartaric acid >oxalic acid > acetic acid. At different contents of organic acids, the effect of the high content organic acids was stronger than that of low content ones.5. The adsorption isotherms for Cd2+ on soils were in agreement with the Langmuir equation (R2>0.95, n=7). The maximum sorption capacity of Cd2+on soils followed the series: yellow cinnamon soil (1146g/kg)> brown red soil (611.6g/kg) > yellow brown soil (593.9g/kg) > latosol (463.6g/kg) > red soil (453.8g/kg). Ad更多还原