西北典型林地和农田土壤锌的吸附-解吸特性研究

Zinc Adsorption-Desorption Characteristics of Typical Forest and Farmland Soils in Northwest China

采集我国西北地区的黄绵土、土娄土和石灰性褐土3种典型土壤,分别包括农田和自然林地土壤,通过不同土壤类型及利用方式的比较,研究这三类土壤对锌的吸附-解吸特性。结果表明,各土壤对锌的吸附量均随平衡液锌浓度的增加而增大,均可用Langmuir方程、Freundlich方程和Temkin方程来描述,相关系数均达到显著或极显著水平;土壤对锌的解吸量随吸附量的增大而增加。在3种土壤中土娄土对锌的最大吸附量、最大缓冲容量以及对锌的吸附作用力以及固定量都最大;石灰性褐土对锌的最大吸附量大于黄绵土,而黄绵土对锌的最大缓冲容量、吸附作用力和固定量大于石灰性褐土。3种土壤对锌的吸附和解吸曲线有明显的相似性,自然林地土壤改为农田利用后,土壤对锌吸附-解吸性质均有一定的变化,但变化不是太大。

This paper studied adsorption-desorption characteristics of zinc （Zn） by three typical types of soil in northwest China, namely the old manured loessal soil, yellow loessal soil and calcareous cinnamon soil. The results showed that the amount of soil adsorbed Zn increased with the initial concentrations of Zn. The Zn isothermal adsorption curves for these three types of soil fitted very well with Langmuir equation, Freundlich equation and Temkin equation as well. The coefficients are all 〉0.9. It was also observed that the amount of desorbed Zn from Zn absorbed soil increased with the amount of soil adsorbed Zn. The relationship between soil Zn adsorption and desorption was well fitted with linear regression （ R^2 was 〉0.9 for every soil）. Among the three types of soil, the old manured loessal soil exhibited the greatest ability in the maximun Zn adsorbed by soil, the maximum soil Zn buffering capacity, the intensity of soil Zn adsorption and the amount of soil Zn rentention. The maximun adsorbed Zn by the calcareous cinnamon soil was greater than yellow loessal soil, but the maximum soil buffering capacity, the intensity of soil Zn adsorption and the amount of soil Zn retention was less than yellow loessal soil. Modern land use （farmland soil） showed small influence on these soil characteristics compared to the effect of soil type.