丽江高铬区土壤-白菜铬迁移特征与阈值研究

Migration characteristics and threshold of chromium in soil-cabbage of high chromium background area in Lijiang City,China

为探明云南典型高背景区白菜土壤铬的阈值,减轻高铬背景值对白菜生长及人体健康可能带来的潜在风险,本研究选取具有高铬背景值的典型土壤,选种当地大宗种植的白菜品种(德高CR117)开展外源添加铬(CrCl_(3)·6H_(2)O)的盆栽试验,并采用物种敏感性分布法(SSD)研究土壤-白菜铬的迁移特征与阈值。结果表明,随着土壤总铬含量的增加,土壤有效态铬浓度呈线性增加,总铬含量在293~837 mg·kg^(-1),对应的有效态铬含量在0.017~0.999 mg·kg^(-1);白菜可食部分铬含量呈线性升高,而白菜根中铬含量呈“S”型曲线,白菜可食部位和根中铬浓度分别在0.025~0.282 mg·kg^(-1)和0.294~2.680 mg·kg^(-1),可食部位铬含量均低于国家食品限量标准,根中铬比可食部分最大高18.7倍,大部分铬积累在根中,并未大量转移到可食部分;除外源添加铬100 mg·kg^(-1)处理外,白菜可食部分产量均显著低于对照组,外源添加铬400 mg·kg^(-1)处理组的产量显著降低,与对照组相比,下降幅度达12.9%,白菜根生物量也随土壤铬含量增加而显著线性下降;通过SSD曲线分析,初步建立白菜种植受影响的累积概率达到5%时土壤中总铬和有效态铬阈值(HC5)分别为1100 mg·kg^(-1)(R^(2)=0.9763)和0.122 mg·kg^(-1)(R^(2)=0.9654)。研究表明,随着土壤总铬含量的增加,土壤中铬有效态浓度和白菜可食部分铬含量均呈线性升高,当土壤总铬含量达到一定阈值后造成白菜产量显著降低,影响白菜生产,建议当地种植低富集铬的白菜品种。

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(CrCl_(3)·6H_(2)O)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 1100 mg·kg^(-1)(R^(2)=0.9763)and 0.122 mg·kg^(-1)(R^(2)=0.9654),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.