大气颗粒物对水芹和白菜可食部位铅镉砷累积的影响

近年来京津冀地区雾霾天气频发,大气颗粒物聚集为其主要原因之一.细颗粒物负载的重金属一定程度上会影响叶菜类蔬菜可食部位重金属的积累.本研究以水生和旱生叶菜类蔬菜水芹、白菜为主要对象,采用营养液培养和土壤培养试验,探索了不同生长环境下(生活区和工业区,以室内培养箱作为对照)蔬菜可食部位铅(Pb)、镉(Cd)、砷(As)的累积特征及大气颗粒物的贡献程度.结果表明,水芹、白菜可食部位Pb、Cd、As含量呈现工业区生活区对照的趋势(p0.05),其中工业区生长的水芹、白菜中Pb含量分别为对照的49.1倍和20.0倍,均超出我国食品安全标准中叶菜蔬菜铅的安全限值(GB 2762-2012).经分析工业区大气颗粒物对水芹、白菜Pb累积贡献率分别高达98%和93%,工业区大气PM_(2.5)中Pb质量浓度显著高出生活区24.3倍(p0.01),且土培白菜与大气PM_(2.5)中Pb含量呈极显著的正相关关系,这些均表明大气颗粒物对叶菜类蔬菜中铅富集的直接影响.此外,尽管大气颗粒物对水芹和白菜中Cd、As的累积贡献高达78.3%~99.3%,但工业区大气PM_(2.5)中Cd、As的质量浓度相对较低,因此,所有水芹、白菜样品中Cd、As含量均符合我国食品安全标准.综上所述,大气颗粒物直接影响着露地叶菜类蔬菜可食部位重金属的富集.

Effects of atmospheric particulate matters on accumulation of Pb, Cd, As in edible parts of cress and cabbage

High level of atmospheric particulate matters is one of the main reasons for frequent fog/haze weather in Beijing-Tianjin-Hebei region. Heavy metals in fine particulate matters influence their accumulation in edible parts of vegetables in some extent. The soil and hydroponic pot experiments were conducted to investigate the effects of atmospheric particulate matters on accumulation of Pb, Cd and As in edible parts of cress (Brassica pekinensis) and cabbage (Oenanthe javanica (B.) DC) in different growth environments, e.g. industrial area, living district, and the control (growth chamber in the lab). The results showed that the concentrations of Pb, Cd and As in edible parts of vegetables followed the sequence of industrial area > living district > control (p<0.05). The concentrations of Pb in cress and cabbage grown in nutrient solution of the industrial area were 49.1 and 20.0 times that of the control and higher than the safety limitation of contaminants in leaf vegetables (GB 2762-2012). Furthermore, contributions of atmospheric particulate matters in industrial area to Pb concentrations in cress and cabbage were significantly high, accounting for 98% and 93%, respectively. Pb concentrations in PM_2.5 from industrial area were 24.3 times that of the living district (p<0.01), and there was an extremely significant positive correlation between Pb concentrations in PM_2.5 and cabbages from soil culture. These indicated the atmospheric particulate matters had direct impact on accumulation of Pb in leaf vegetables. Although the contributions of atmospheric particulate matters to concentrations of Cd and As in cress and cabbage ranged at 78.3%~99.3%, the concentrations of Cd and As in PM_2.5 from industrial area were relatively lower, which could explain the lower concentrations of Cd and As in all cress and cabbage than the safety limitation of contaminants in leaf vegetables (GB 2762-2012). In conclusion, the atmospheric particulate matters had significant influence on the accumulation of heavy metals in edible parts of outdoor leaf vegetables.