The Research On Species And Bioavailability Of Cd Of Soils In Chengdu And Other Areas

Based on the main research region of chengdu and the object of soil andvegetable, the distribution of Cadmium species and bioavailability of Cd were studied.The researched contents are incluing: The method for determination of the traceCd in soil and vegetable by hydride generation-atomic fluorescence spectrometry wasimproved; the distribution of Cd species in different soil; the correlation between thedistribution of Cd species and the soil properties were studied.;The bioavailability ofCd in chengdu soil was investigated.Solutions presented in the research can be summarized as follows:8-hydroxyquinoline and cobalt ion have synergistic enhancement effects for Cdhydride generation, and can eliminate the interference of heavy metal elements. Theanalysis method has been successfully established to measure trace Cd in vegetablesand soil.It has been found that 80% soil samples were polluted with Cd.There was asignificant liear correlation between available Cd and total Cd:Cd_Ava=0.27 [Cd]_Total-0. 0049. The distribution of Cd species in these soils were veryvariable.Both Carbonate-bound Cd and Fe-Mn oxide-bound Cd have strong variation,and the other three specice have median variation. The availability is thecomprehensive expression for each specice. The exchangeable and Carbonate-boundCd was the main contribution to the availability. The Cd specice was influenced bythe environmental conditions, such as soil physical and chemical properties, pH is thedominant factor. The correlation between exchangeable and Fe-Mn oxide-bound Cdand soil factors is not significant,. Carbonate-bound Cd is significantly correlated withpH and CaCO₃. The correlation between organic bound Cd and organic matter isnegatively significant. The correlation between residual Cd and pH is also negativelysignificant. It has been found that the exchangeable Cd decreased with increasingCaCO₃, however, Carbonate-bound Cd and residual Cd increased. The exchangeableCd and Carbonate-bound Cd were influenced in the same way by the CaCO₃ and P,but the residual Cd was contrary. The content of Cd in most vegetables which hasbeen investigated exceed the national food health standard. The accumulation factororder of vegetable to Cd is spinach＞celery＞radish,cabbage. The distribution orderof Cd in spinach and radish is leave＞root＞stem. That for Cd in celery and cabbage is root＞stem＞leave and leave＞stem＞root, respectively. Most of the correlations betweenCd concentrations for every part of vegetables and the corresponding soil availabileCd are more significant than those between Cd concentration in every part of thevegetables and the total soil Cd.It is indicated by this fact that relationship betweenCd in vegetables and the availability Cd is closer than those between the total Cd. Therelationship between the Cd for most vegetables and the corresponding soil total Cd oravailability Cd can be best described by logarithmic model y=alnx+b.