Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Chine → 2008 → Study on the Mechanisms of Sorption-Desorption of Heavy Metals and Its Application in the Irrigated Desert Soils from the Oasis Regions, Northwest China

Lanzhou University (2008)

Study on the Mechanisms of Sorption-Desorption of Heavy Metals and Its Application in the Irrigated Desert Soils from the Oasis Regions, Northwest China

Wang Sheng Li

Titre : Study on the Mechanisms of Sorption-Desorption of Heavy Metals and Its Application in the Irrigated Desert Soils from the Oasis Regions, Northwest China

Auteur : Wang Sheng Li

Grade : Doctoral Dissertation 2008

Université : Lanzhou University

Résumé
Sorption -desorption of heavy metals is one of the primary processes that affects the fate and mobility of heavy metals in soils.Sorption-desorption play a dominant role in the plant nutrition and pollution control.For heavy metals such as Cu,Zn,Pb,Cd,Ni etc,these reactions have a large effect on their availability to plants and on the extent to which these heavy metals pass into the foood chain.Laboratory batch experiments,single extraction procedure,sequential extraction procedure,and simple correlation analysis were carried to study the sorption and desorption in the irrigated desert soil from the oasis in the arid regions,northwest China.These studies will provid the basic data for chemical behavior in the irrigated desert soils from the oasis,and will provide a scientific basis for the assessment of ecological risk and remediation of soils contaminated by heavy metals.The main results show as follows :(1)Total Cu content of soils used in the sorption-desorption tests for single heavy metal and Combined heavy metals ranged from 31.73 to 59.12 mg/kg ;Total Zn content of soils ranged from 33.53 to 61.22 mg/kg ;Total Pb content of soils ranged from 12.16 to 34.13 mg/kg ;Total Cd content of soils ranged from 0.26 to 0.52 mg/kg ;Total Ni content of soils ranged from 22.64 to 41.58 mg/kg.The concentration of Cu,Zn,Pb,Cd,and Ni were much less than Cu,Zn,Pb, Cd,and Ni limit ofⅡgrade soil environmental quality in the the Environmental Quality Standard for Soils in China,indicating all the soils studied for sorption-desorption tests could be considered uncontaminated.(2)Under the conditions of a single heavy metal,the amount of heavy sorbed varied with soil properties,the concentration and type of heavy metal.The sequence of heavy metal adsorption capacity has been found for the irrigated desert soils in the order Pb>Cu>Zn. Sorpfion of Cu、Zn、Pb in the irrigated desert soils was well described by Freundlich sorption model ;Sorption of Pb in the irrigated desert soils was also well described by Henry sorption model.Heavy metals sorption capacity of the irrigated desert soils is likely to be controlled by a combination of soil characteristics such as texture,pH,organic matter,CaCO3,and CEC rather than a single factor such as pH Or organic matter.At low concentration,the percent of desorption of heavy metals in soils is smaller ;At higher heavy metal additions,the percent of desorption of heavy metals in soils is larger.The sequence of heavy metal desorption percent was in the order Cu>Zn>Pb,indicating the sequence of heavy metal bioavailability is also in the order Cu>Zn>Pb.Secondary power function can be used to simulate the relationship between desorption amount of heavy metals and sorption amount before desorption in the irrigated desert soils.(3)Copper was distributed mainly in the residual fraction in the natural irrigated desert soils.The high adsorption capacity of copper and unreversible adsorption of copper(low exchangeable fraction)in the irrigated desert soils,indicating that copper can be very strong maintained by the irrigated desert soils,thus reducing the risk of groundwater and food chain contamination under the general conditions.At low copper concentration,the percent of Cu in organic fraction is larger than that of at higher copper additions,which indicates that copper gives priority to the organic matter in the irrigated desert soils

Mots clés : The oasis in the arid regions The irrigated desert soil Heavy metal Bioavailability Sorption-desorption Fraction analysis

Présentation (Dissertationtopic)

Page publiée le 1er mai 2013, mise à jour le 10 janvier 2018