龙胜县丘陵山区土壤与罗汉果重金属含量及潜在生态危害评价——以宝赠村为例

桂林市龙胜县作为罗汉果的三大主产区之一,种植区土壤重金属含量及罗汉果质量影响到该区罗汉果产业的健康发展。为探索龙胜县丘陵山区典型贫困村罗汉果园的安全性,该文研究了宝赠村典型罗汉果园土壤及罗汉果果实中砷、铜、锌、铅、镉、铬、汞7种重金属含量,并采用Hankanson指数法分析了其潜在生态风险。结果表明:(1)龙胜丘陵山区罗汉果园土壤(0~10 cm,10~20 cm)重金属含量均达到国家农业用地土壤筛选值标准(GB15618-2018),其中0~10 cm土壤中砷、铜、锌、铅、镉、铬、汞的含量分别为3.67、18.00、58.39、17.01、0.10、28.57、0.08 mg·kg^-1,10~20 cm土壤中砷、铜、锌、铅、镉、铬、汞的含量分别为1.93、12.56、21.47、10.51、0.04、17.09、0.02 mg·kg^-1。(2)在0~10 cm和10~20 cm土层中,重金属的生态风险状况总体上处于轻微生态风险等级,综合生态风险指数分别为105.29和38.96;0~10 cm土层不同重金属潜在的生态风险顺序为汞>镉>铅>铜>砷>锌>铬,汞、镉的生态风险分别为50.16、42.05,在总重金属风险中贡献率分别占所有重金属的47.6%和39.9%,已达中等生态风险等级;在10~20 cm土层中,7种重金属的生态风险大小关系为镉>汞>铜>铅>砷>铬>锌。(3)研究区罗汉果果实中砷、铜、锌、铅、镉、铬、汞的含量分别为0.00024、0.273、1.10、0.0016、0.00013、0.00013、0.00012 mg·kg^-1,其生态风险状况均处于轻微风险等级,7种重金属的生态风险顺序为汞>铜>镉>锌>铅>砷>铬,综合生态风险指数为0.21193,几乎不存在生态风险。因此,在龙胜县丘陵山区典型贫困村——乐江镇宝赠村推广种植的罗汉果达到了安全质量标准。

Contents and potential ecological risk assessment of heavy metals in soil and Siraitia grosvenorii at the hilly region in Longsheng County Taking Baozeng Village as an example

Longsheng County is one of the three main producing areas of Siraitia grosvenorii in Guilin City, the contents of heavy metals in soil and S. grosvenorii might affect the healthy development of S. grosvenorii in this area. To explore the safety of S. grosvenorii orchard, heavy metals(As, Cu, Zn, Pb, Cd, Cr, Hg)in the soil(0-10 cm,10-20 cm)and fruit of S. grosvenorii in the hilly region in Longsheng were measured, and their potential ecological risks were evaluated through Hankanson method. The results were as follows:(1)The average content of the heavy metals in the soil(0-10 cm,10-20 cm)of S. grosvenorii orchard reached the Eco-SSLs standard request of the national agricultural land evaluation criterion(GB-15618-2018), with the average values in soil(0-10 cm)of As, Cu, Zn, Pb, Cd, Cr, Hg were 3.67, 18.00, 58.39, 17.01, 0.10, 28.57, 0.08 mg·kg^-1, and in soil(10-20 cm)were 1.93, 12.56, 21.47, 10.51, 0.04, 17.09, 0.02 mg·kg^-1, respectively.(2)The ecological risk status of heavy metals in soil(0-10 cm)of S. grosvenorii orchard in the hilly region of North Guangxi was a low ecological risk generally. The average ecological risk index values at different points were 105.29, which represented a low ecological risk. The potential ecological risk decreased with the sequence of Hg, Cd, Pb, Cu, As, Cr and Zn, and all the metals except for Hg and Cd had a low ecological risk. The potential ecological risk index caused by Hg and Cd reached 50.16 and 42.05, representing a moderate ecological risk, which contributed around 47.6% and 39.9% of the total potential ecological risk. The ecological risk status of heavy metals in soil(10-20 cm)of S. grosvenorii orchard was a low ecological risk. The average ecological risk index values at different points were 38.96, which had a low ecological risk. The potential ecological risk decreased following the sequence of Cd, Hg, Cu, Pb, As, Cr and Zn.(3)The average content of the heavy metals in the fruit of S. grosvenorii orchard with the values of As, Cu, Zn, Pb, Cd, Cr, Hg were 0.000 24, 0.273, 1.10, 0.001 6, 0.000 13,0.000 13 and 0.000 12 mg·kg^-1, respectively, which represented a low ecological risk. The potential ecological risk decreased with the sequence of Hg, Cu, Cd, Zn, Pb, As and Cr. It was showed that the average ecological risk index values of different samples were 0.211 93, with little ecological risk. Therefore, the S. grosvenorii planted at Baozeng Village reached the safety and quality standard.