菜薹（菜心）对土壤中重金属的富集特征及产地土壤安全临界值

通过采集珠三角地区蔬菜产地原位土壤（非人工添加重金属）进行盆栽试验，研究了Cd、Pb、As、Hg、Cr 5种重金属在种植菜薹土壤中的活性，菜薹可食部分对土壤中全量和有效态重金属的富集特征，并探讨了5种重金属在土壤产地环境中的安全临界值以及土壤理化性质对菜薹吸收重金属的影响。结果表明：种植菜薹的土壤中重金属的活性顺序为Cd＞Pb＞As＞（Cr、Hg），菜薹对重金属的富集能力顺序为Cd＞Cr＞As＞Pb。依据《食品中污染物限量》（GB2762-2005）进行方程拟合，得出适合菜薹种植土壤的重金属全量限量值分别是：Cd，1.18 mg?kg-1|Pb，401.93 mg?kg-1|As，25.67 mg?kg-1|Cr，150.71 mg?kg-1，有效态重金属限量值分别是：Cd，0.64 mg?kg-1|As，3.05 mg?kg-1|Cr，4.93 mg?kg-1。菜薹对Hg富集能力弱，在供试土壤Hg浓度范围内菜薹中Hg含量均未超过限量值。

Heavy Metal Accumulation Characteristics and Environmental Critical Values in Flowering Cabbage〔Brassica campestris L.ssp.chinensis(L.)var.utilis Tsen et Lee〕Production Area for Food Security

Vegetable field soil in situ at the Pearl River delta was collected，and the pot experiment was conducted to study the activities of 5 heavy metals（Cd、Pb、As、Hg、Cr）in soil and the enrichment characteristics of total and available heavy metals in soil by the edible parts of flowering cabbage〔Brassica campestris L. ssp. chinensis（L.）var. utilis Tsen et Lee〕．The environment critical values of 5 heavy metals in flowering cabbage production area for food security，and the impact of soil physicochemical properties on heavy metal absorption in flowering cabbage were explored．The results show that the activity of soil heavy metals（ranked from the highest to the lowest）is Cd＞Pb＞As＞（Cr、Hg），and the heavy metals concentration（ranked from the highest to the lowest）is Cd＞Cr＞As＞Pb．Based on the national standards for maximum levels of heavy metal contaminants in foods（GB 2762-2005），the environmental critical values in the vegetable field were calculated as Cd 1.18 mg?kg-1，Pb 401.93 mg?kg-1，As 25.67 mg?kg-1，Cr 150.71 mg?kg-1，and the critical values of soil available heavy metal were calculated as Cd 0.64 mg?kg-1，As 3.05 mg?kg-1，Cr 4.93 mg?kg-1．The content of Hg in edible parts of flowering cabbage used in the experiment were lower than the criterion．