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

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(R2 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.