用于表征三七种植区土壤中可利用态砷的化学提取剂的筛选

为正确表征云南文山三七种植区土壤中植物可利用态砷,选取NaH2PO4（0.5mol·L-1）、H2O、H3PO4（0.2mol·L-1）、EDTA（0.0625mol·L-1,pH=7）、NH4C（l1.0mol·L-1）和（NH4）2SO（40.05mol·L-1）6种提取剂,比较了它们对土壤中砷的提取效果,及其所提取的砷与三七植株各部位砷含量之间的相关关系。结果表明,NaH2PO4、H3PO4和（NH4）2SO4这3种提取态砷与土壤总砷呈极显著正相关,相关系数分别为0.8359、0.8177和0.8810。NaH2PO4和H3PO4的提取效率较高,平均提取效率分别为6%和11%;而（NH4）2SO4提取效率较低,平均仅为0.084%。NaH2PO4和（NH4）2SO4提取态砷与三七主根、须根和茎部砷含量呈显著正相关,H3PO4提取态砷与三七主根和须根砷含量呈显著正相关。综合考虑认为NaH2PO（40.5mol·L-1）是最佳提取剂,H3PO（40.2mol·L-1）提取剂次之,这两种提取剂均可较好地表征土壤中砷的三七可利用性。

Screening of Chemical Extracting Agents for Characterizing Soil Bio-effective Arsenic on Panax Notoginseng

In order to characterize the plant availability of arsenic（As） in the soil of a Panax notoginseng plantation in Wenshan（Yunnan Province,China）,six chemical extracting agents including 0.5 mol·L-1 NaH2PO4,H2O,0.2 mol·L-1 H3PO4,0.062 5 mol·L-1 EDTA（pH=7）,1.0 mol·L-1 NH4Cl,and 0.05 mol·L-1（NH4）2SO4 were selected to extract As from soil samples.The correlation between the As concentrations of the soil extracts and the total As in the soil were analyzed.The results showed that the As concentrations in the soil solutions extracted by 0.5 mol·L-1 NaH2PO4,0.2 mol·L-1 H3PO4 and 0.05 mol·L-1（NH4）2SO4 were correlated well with the total As concentration in the soils,with correlation coefficients of 0.835 9,0.817 7,and 0.881,respectively.The extract efficiencies of 0.5 mol·L-1 NaH2PO4 and 0.2 mol·L-1 H3PO4 were 6% and 11%,respectively,which were much higher than that of 0.05 mol·L-1（NH4）2SO4.The correlation of As concentrations between the extract and different parts of the plant is important for selecting appropriate chemical extracting agents.The As concentrations in the 0.5 mol·L-1 NaH2PO4 and 0.05 mol·L-1（NH4）2SO4 extracts were significant positively correlated with the As concentrations in the taproot,fiber and stem of P.notoginseng,whereas that of the 0.2 mol·L-1 H3PO4 extract was significantly positively correlated only with the taproot and fiber portion.In conclusion,NaH2PO4（0.5 mol·L-1） and H3PO4（0.2 mol·L-1） both could be selected to characterize soil bio-effective As on Panax Notoginseng.