蓬莱仙界园区土壤-蔬菜系统重金属形态解析及关联特征

Speciation Analysis and Association Feature of Heavy Metals in Soil-vegetable System of Penglai Paradise

为了解贵阳市蓬莱仙界生态园区土壤-蔬菜系统中重金属的赋存形态及其内在的关联特征,采用Nemero综合污染指数和综合质量影响指数IICQ分析了番茄(Lycopersicon esculentum)、甘蓝(Brassica oleracea)、红油菜(Brassica napus)、豌豆(Pisum sativum)、白菜(Spinacia oleracea)、胭脂萝卜(Raphanus sativus)地土壤-蔬菜系统重金属Pb、Cr、Cd、Hg、As的综合污染状况,并依据重金属生物有效性、形态解析和富集系数对土壤-蔬菜系统中重金属的关联特征进行了表征。结果表明:土壤重金属综合污染指数为番茄地(2.98)>甘蓝地(2.90)>红油菜地(2.36)>豌豆地(2.33)>白菜地(2.18)>胭脂萝卜地(1.85),番茄土壤和甘蓝土壤属于中度污染,胭脂萝卜土壤污染最轻,土壤中Hg的单因子污染指数最大,其含量高于贵州省背景值2~3倍。BCR连续分级提取结果表明:研究区Pb、Cr、Cd和As以残渣态为主,Cr、Hg和As的形态分布相似,Cd的酸可提取态占总量的比例最大,为14.81%,活性态比例大小顺序为:Hg(48.98%)>Cd(44.44%)>Pb(39.40%)>Cr(10.37%)>As(1.18%),同种元素的不同形态所占比例不同,其中,Hg、Cd和Pb的活性态含量较高,潜在危害较大。土壤-蔬菜系统重金属IICQ指数大小顺序为:番茄(3.92)>红油菜(3.37)>白菜(3.33)>胭脂萝卜(3.32)>甘蓝(3.25)>豌豆(2.74),除土壤-豌豆系统属轻度污染外,其余属中度污染;蔬菜综合质量影响指数表明,番茄的IICQ_v最大,为2.50,污染最严重。番茄叶和白菜叶对Hg的富集系数均高于其他蔬菜的叶组织,不同蔬菜和不同组织部位对Pb、Cr、Cd、Hg和As的富集能力差异明显,番茄根和胭脂萝卜根对Pb的富集能力远高于茎叶,Pb主要累积在豌豆和甘蓝的茎部,其次为根部,红油菜叶和白菜叶对Pb的富集系数高于其根茎;甘蓝、白菜和红油菜富集Cd能力较高,豌豆对Cd的富集能力最弱、IICQ_V最小,受污染最轻,抵抗重金属能力最强。

To clearly understand the heavy metals forms and associated features in Penglai Fairyland Park soil-vegetable system,we determined the different forms contents of Pb,Cr,Cd,Hg and As in soil and vegetable tissues.The heavy metal pollution situation in soil-vegetable system were analyzed by Nemero comprehensive pollution index and IICQ,the heavy metals correlation characteristics was characterized according to bioavailability,speciation analysis and enrichment coefficient of heavy metals in the soil-vegetable system.The results showed that comprehensive pollution index of heavy metals in soil was Lycopersicon esculentum(2.98)>Brassica oleracea(2.90)>Brassica napus(2.36)>Pisum sativum(2.33)>Spinacia oleracea(2.18)>Raphanus sativus(1.85),Lycopersicon esculentum soil.Brassica oleracea soil pollution belonged to the middle pollution level,Raphanus sativus soil pollution belonged to light pollution level.The single factor pollution index of Hg in soil was the highest,which was 2~3 times higher than Guizhou background value.BCR result showed that Pb,Cr,Cd and As in soil were mainly as residual state,the speciation distributions of Cr,Hg and As was similar,the percentage of extractable acid of Cd(14.81%)was much higher than that of other elements.The proportion of the active state was:Hg(48.98%)>Cd(44.44%)>Pb(39.40%)>Cr(10.37%)>As(1.18%),Among them,Hg,Cd and Pb had higher content of active state and higher potential hazard.The order of heavy metal index in soil vegetable system in different vegetable planting areas was:Lycopersicon esculentum(3.92)>Brassica napus(3.37)>Spinacia oleracea(3.33)>Raphanus sativus(3.32)>Brassica oleracea(3.25)>Pisum sativum(2.74),except for the soil-pea vegetable system,which belonged to slight pollution,other soil-vegetable research systems belonged to moderate pollution.According to the comprehensive quality index of vegetables,the maximum IICQv of Lycopersicon esculentum was 2.50,and the pollution was the most serious;The enrichment coefficient of Lycopersicon esculentum leaves and Spinacia oleracea leaves on Hg was higher than that of other vegetable leaves.The enrichment abilities of Pb,Cr,Cd,Hg and As in different vegetables and different tissue parts were significantly different.Lycopersicon esculentum root and Raphanus sativus root radionuclide Pb enrichment ability was much higher than the stems and leaves.Pb mainly accumulated in the Pisum sativum and Spinacia oleracea stems,followed by the root.Pb enrichment coefficient of Brassica napus leaves and Spinacia oleracea leaves was higher than its rhizome.Spinacia oleracea and Brassica napus had higher Cd enrichment capacity,while Pisum sativum had the weakest Cd-enrichment capacity,the lowest IICQv,the least pollution and the strongest resistance to heavy metals.