天津某菜地土壤——蔬菜中硒与重金属含量特征及绿色富硒蔬菜筛选

Characteristics of selenium and heavy metals concentrations in soils and vegetables and screening of green selenium-enriched vegetables in a base of Tianjin

本文以天津某蔬菜基地为研究对象,对基地土壤中硒与重金属元素含量进行了分析,并利用单因子评价法对土壤中重金属元素进行了评价.结果表明,蔬菜基地的土壤Se含量范围为0.71—1.23 mg·kg^(-1)(干重),平均含量为0.96 mg·kg^(-1),所有样品均达到富硒土壤(Se≥0.04 mg·kg^(-1))标准.但是蔬菜基地遭到重金属不同程度的污染,其中Hg、Zn和Cu的污染指数分别为1.24、1.02和1.23,污染程度均为轻度,而Cd的污染指数为2.26,达到中度污染.另外,对与土壤配套采集的青萝卜、圆白菜和菜花等20种蔬菜中的硒与重金属含量进行分析,结果表明该基地蔬菜的富硒(Se≥0.01 mg·kg^(-1))率达到90%.蔬菜中青萝卜1号(本地)、青萝卜2号(天津青萝卜)和青萝卜3号(津卫一号)的硒含量较高,含量分别为0.100、0.091、0.078 mg·kg^(-1)(鲜重),硒含量较低的蔬菜为油菜1号(金品一夏)、油菜2号(改良金品雨季)和小白菜2号(佳美),含量分别为0.007、0.007、0.009 mg·kg^(-1).每种蔬菜的Cd、Zn和Cu的含量均低于食品安全国家标准要求,但圆白菜1号(雅实绿)、圆白菜2号(珍美)、菜花1号(本地)和菜花2号(白雪)中的Hg含量分别为0.022、0.018、0.019、0.016 mg·kg^(-1),均超过食品安全标准限值.同时,健康风险评价结果显示,食用本基地圆白菜(雅实绿、珍美)、菜花(本地、白雪)和香菜(本地)对人体造成健康风险较大.综合各类分析评价结果,该基地生产的3种青萝卜(本地、天津青萝卜、津卫一号)均为绿色富硒蔬菜,建议当地农户多种植该类蔬菜.

Concentrations of selenium and heavy metals were analyzed in soil of a vegetable base in Tianjin, and single factor index was used to evaluate heavy metals. The results showed that the selenium concentration of soil was 0.71-1.23 mg·kg^-1(dry weight), and average concentration was 0.96 mg·kg^-1. All samples reached the standard of selenium-enriched soil (Se ≥ 0.04 mg·kg^-1). However, the soil was polluted with Cd, Hg, Zn and Cu, and the pollution index was 2.26, 1.24, 1.02 and 1.23, respectively. The pollution level of Hg, Zn and Cu was mild, while Cd was moderate pollution. In addition, the concentrations of selenium and heavy metals in 20 vegetables such as green radish, cabbage and cauliflower were analyzed. The results showed that the selenium-enriched rate of vegetables reached 90%. High levels of selenium were detected in green radish No.1 (local), green radish No.2 (Tianjin green radish) and green radish No.3 (Jinwei No.1), and the concentration was 0.100, 0.091 and 0.078 mg·kg^-1, respectively (fresh weight). Low levels of selenium were detected in Bok choy No. 1 (Jinpinyixia), Bok choy No. 2 (Improved jinpinyuji) and pakchoi No. 2 (Jiamei), and the concentration was 0.007, 0.007, and 0.009 mg·kg^-1, respectively. The concentration of Cd, Zn, and Cu in each vegetable was lower than the national standard requirements for food safety, but the Hg concentration in cabbage No. 1 (Yashilv), cabbage No. 2 (Zhenmei), cauliflower No. 1 (local), and Cauliflower No. 2 (Baixue) was 0.022, 0.018, 0.019, and 0.016 mg·kg^-1, respectively and higher than the national standard requirements for food safety. Meanwhile, the health risk assessment showed that consumption of cabbage (Yashilv and Zhenmei), cauliflower(local and Baixue) and caraway could cause higher health risk. According to the results, 3 green radish produced in this vegetable base were green selenium-enriched vegetables, and the local farmers should be advised to grow vegetables.