EFFECTS OF SOIL CESIUM CONTAMINANTS ON RAPE(Brassica campestris)ROOT EXUDATES OF LOW MOLECULAR WEIGHT ORGANIC ACIDS IN RHIZOSPHERE SOILS

摘要

Soils have become contaminated with radionuclides as a result of nuclear testing,accident spills and emissions from all nuclear fuel cycle operations or nuclear energy generation.~(137)Cs is a long-lived(t_(1/2)30.2 year)by-product of nuclear fission.Cesium in contaminated food is easily transferred to man and animals,making soil-plant transfer an important link in the chain of events which leads to its entry into human food chain.Recently,biological methods for radionuclide removal had been used,especially using plants to remove radionuclides from environment(Zhu and Shaw,2000).It is well recognized that the rhizosphere is a zone of increased microbial activity and biomass under the influence of plant roots,which can exude substances such as carbohydrates and low molecular weight organic acids(LMWOAs).LMWOAs are important root exudates,whose metal chelating and/or complexing properties for mobilization of mineral nutrients can influence metal release from soil and uptake by plants.The objectives of this research were to evaluate cesium accumulation in shoots of rape grown in pot experiments with contaminated soils,and assess the effect of LMWOAs on the uptake of Cs by rape under pot experiments