Migration characteristics and threshold of chromium in soil-cabbage of high chromium background area in Lijiang City,China
Pot experiments were conducted using locally grown Chinese cabbage varieties(DEGAO CR117)to determine the safe threshold of chromium in soil for Chinese cabbage in high-background areas in Yunnan and mitigate potential risks to plant growth and human health.The experiments involved adding chromium(CrCl3·6H2O)to typical soil with high chromium background values.The Species Sensitivity Distribution(SSD)method was used to investigate chromium migration characteristics and threshold in the soil-Chinese cabbage system.The results revealed a linear increase in the concentration of available chromium in the soil with an increase in total chromium content in each pot,ranging from 293 to 837 mg·kg-1;the content of available chromium ranged from 0.017 to 0.999 mg·kg-1.The chromium content in the edible part of Chinese cabbage exhibited a linear increase,whereas that in the root of Chinese cabbage followed an S-shaped curve.The chromium concentrations in the edible part and roots of Chinese cabbage ranged from 0.025 to 0.282 mg·kg-1 and 0.294 to 2.680 mg·kg-1,respectively.Notably,the chromium content in the edible parts was lower than the national food limit standard,and the chromium content in the roots was 18.7 times higher than that in the edible part.Most chromium accumulated in the roots did not significantly transfer to the edible part of Chinese cabbage.The yield of the edible part was significantly lower than that of the control group,except for the 100 mg·kg-1 treatment of source-added chromium.Moreover,the addition of 400 mg·kg-1 chromium significantly decreased the yield,with a reduction rate of 12.9%.The root biomass of Chinese cabbage also decreased linearly with an increasing chromium content in the soil.The SSD curve analysis showed that the HC5 values for the total and available chromium contents in Chinese cabbage planting soil were preliminarily established as 1 100 mg·kg-1(R2=0.976 3)and 0.122 mg·kg-1(R2=0.965 4),respectively.These findings suggest that the available chromium concentration in the soil and chromium content in cabbage edible parts increase linearly with increasing soil total chromium content.However,once the soil total chromium content surpassed a certain threshold,it notably decreased cabbage yield,impacting cabbage production.Therefore,cabbage varieties should be grown with low chromium enrichment in the local area.
Brassica rapa var.glabra Regelsafety thresholdchromiumspecies sensitivity distributionhigh background area
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