Study On Cadmium Pollution And Its Forms Analysis Of Soil-Vegetable System In Wastewater Irrigation Region In Changchun City

Wastewater irrigation as a measure of saving water plays a indispensable part in oureconomic development. And wastewater irrigation region in Changchun City traces back tomore than thirty years ago, without any report and analysis about the qualification ofWastewater irrigation and crop quality. Wastewater samples were taken and analyzed insuccessive three year past, the result indicates the water quality is all right and under thecriteria in the paper. In the process of investigation of soil and vegetable, the heavy metalCadmium (Cd) content in some soil is approaching or beyond the environmental load, andthat in some vegetable exceptional is beyond the criteria.Because Cd can be transferred and accumulated in the soil-vegetable system, thencumulate in people body by food chain, endanger the health of human. Cd which is absorbedby vegetable is not only depended on the total content of Cd in soil but also reckoned on theform of Cd existence. Based on the evaluation of soil and vegetable qualification in thewastewater irrigation region, different forms of Cd in the eating part of crop in the wastewaterirrigation region and soil itself is analyzed, aiming to find the transfer regulation of Cd in thesoil-vegetable system, then providing science data for the agrotype programming inwastewater irrigation.The conclusions are as followings.1.Contamination indices of the wastewater for irrigation are all under the criteria, whichshow the water quality is all right.2. the heavy metal content in soil and vegetable there is high general, but only some soilsamples exceeds the criteria, as well as tomato and cabbage samples, showing that there arestill some environmental load and endurance remained.3.The exchangeable Cd is related to the vegetable absorption for its significantbiological activity, but the exchangeable Cd and the carbonate combined Cd in the soil is notrelated to the content of Cd in the eatable part of vegetable from the experiment, showing thatCd distribution in the plant organ is not connected with the soil environment.4.The main form of Cd in vegetable is albumen combined, and diverse for differentalbumen. Globulin combined Cd is the main form in tomato, and water-solubility organic acidcombined Cd is the main form in cabbage. So the Cd in tomato and cabbage exceeding thecriteria is harm for eating.