植物对土壤中微量元素的吸收与转移及对生物地球化学异常形成的影响——以广西盐田岭锡石硫化物矿床为例

Absorption and Transfer of Microelements in Soil by Plants and Their Influence on the Formation of Biogeochemical Anomalies as Exemplified by the Yantianling Cassiterite-Sulfide Deposit,Guangxi

为探讨生长于矿床上部植物对土壤中的成矿及伴生元素的吸收和转移及对生物地球化学异常形成的影响,以盐田岭锡石硫化物矿床为例,研究了不同土层及生长其上的杉木、杨梅树和芒萁不同器官中元素的含量特征。研究发现:生长于矿床上部植物中的多数成矿及伴生元素的含量高于背景区,形成了生物地球化学异常,其元素组合同土壤异常大致相似但其衬度均小于土壤,土壤中富集的As、Sb、Bi、Hg、Sn、W在植物中未产生异常。元素在植物不同器官中的积累具有地下部分(根部特别是细根)或地上部分顶部(叶及细枝)富集,中部(木质部及皮)贫化的规律。相对于背景区,矿化异常区植物对多数元素的吸收和转移能力都有不同程度的降低,营养性或毒性较小的元素降低相对较小,而毒性较大的或难溶解的元素降低相对较大。植物对土壤中营养性或毒性较小的元素的吸收和转移可能是无障-半无障的,而对毒性较大的元素或难溶解的元素可能是有障的。无障-半无障型元素有可能产生良好的生物地球化学异常,而有障型元素的生物异常可能不明显甚至不产生。毒性较大的元素由根向叶的转移可能是有障的,其叶部异常可能不明显甚至不产生,但有可能产生清晰的根部异常。

This study investigated the influence of plants growing above the ore deposit on the absorption of ore-forming and associated elements in soil and the formation of biogeochemical anomalies as exemplified by the Yantianling cassitirite-sulfide ore deposit.It also examined the contents and characteristics of elements in different soil layers and in different organs of China fir,strawberry trees and decrano pteris ped growing above.It was found that the contents of most ore-forming and associated elements in the plants growing above the ore deposit are higher than the background values,thus causing biogeochemical anomalies.The soil is enriched in As,Sb,Bi,Hg,Sn and W,showing no anomaly in plants.The elements are highly accumulated in roots or in leaves and fine branches,but depleted in xylem and skin.Relative to the background zone,the capability of plants growing in mineralization anomaly zones to transport and absorb most elements is relatively decreased to different degrees,but the case is not serious for those trophic and less toxic elements and highly serious for those greatly toxic or unsoluable elements.The aborption and transfer of trophic or less toxic elements in soil by plants may be accessible-semi-accessible,but those of greatly toxic or indissoluble elements may be inaccessible.Inaccessbile-semi-accessible type elements may produce good biogeochemical anomalies,while inaccessbile-type elements may produce no biogeochemical anomaly or unremarkable anomaly.The transfer of greatly toxic elements from roots to leaves may be obstructed,and the leaf anomaly may be unobvious or could not be produced,but remarkable root anomalies would be possible.