土壤中砷和硒生物有效态的联合提取

Combined extraction of bioavailability of arsenic and selenium in soils

为了快速、准确和有效地联合提取土壤中生物有效态砷和硒,以减少实验成本和提高实验效率,本研究在长期实验摸索及前人工作基础上,研究0.5 mol·L^(-1)Na HCO_(3)、0.1 mol·L^(-1)HCl、0.5 mol·L^(-1)KH_(2)PO_(4)和0.1 mol·L^(-1)KH_(2)PO_(4)-K_(2)HPO_(4)4种浸提剂对土壤中生物有效态砷和硒的联合提取实验效果。4种浸提剂所得浸提液经HNO_(3)和HClO_(4)消煮,用氢化物发生原子荧光光度计(HGAFS)测定浸提液中砷与硒的浓度。土壤总砷和总硒的测定中使用两组土壤标准物质控制,玉米标准物质控制玉米根和玉米籽实验质量,相对标准偏差均小于10%,硒和砷的检测限分别为0.01μg·L^(-1)和0.05μg·L^(-1)。结果表明:0.1 mol·L^(-1)KH_(2)PO_(4)-K_(2)HPO_(4)和0.5 mol·L^(-1)Na HCO_(3)提取的土壤生物有效态砷、硒含量与土壤总砷(r=0.788,P<0.01;r=0.794,P<0.01)和总硒(r=0.707,P<0.05;r=0.648,P<0.05)均呈显著性正相关,其余两种浸提剂提取效果较差。植物指标法显示,仅0.1 mol·L^(-1)KH_(2)PO_(4)-K_(2)HPO_(4)提取的土壤生物有效态砷、硒含量与玉米根砷(r=0.848,P<0.01)和硒(r=0.822,P<0.01)呈极显著正相关。研究表明,0.1 mol·L^(-1)KH_(2)PO_(4)-K_(2)HPO_(4)作为浸提剂可快速、准确、有效地联合提取土壤中砷和硒的生物有效态。

In this study,to improve experimental efficiency by reducing the number of experimental steps,a rapid,accurate,and effective method for extracting bioavailable As and Se in soils was designed,produced,and evaluated.The experimental effects of four extractants(0.5 mol·L^(-1) NaHCO_(3),0.1 mol·L^(-1) HCl,0.5 mol·L^(-1) KH_(2)PO_(4) and 0.1 mol·L^(-1) KH_(2)PO_(4)-K_(2)HPO_(4))in extracting bioavailable As and Se in soils were compared.Following the mixture and extraction process,the resultant solutions were added to a mixed acid solution of HNO_(3) and HClO_(4) and further digested.Subsequently,a hydride generation atomic fluorescence spectrometer(HG-AFS)was used to determine the content of As and Se.Additionally,soil reference materials were used as controls for determining total As and total Se in soils.The experimental quality of corn root and corn seed was controlled using the corn reference material.The relative standard deviation was within 10%,and the detection limits for Se and As were 0.01μg·L^(-1)and 0.05μg·L^(-1),respectively.We found that the contents of soil bioavailable As and Se extracted using 0.1 mol·L^(-1) KH_(2)PO_(4)-K_(2)HPO_(4) and 0.5 mol·L^(-1) NaHCO_(3) buffer solutions were positively correlated with the total As(r=0.788,P<0.01;r=0.794,P<0.01)and total Se(r=0.707,P<0.05;r=0.648,P<0.05)in soils,whereas the other two extracts were ineffective.The plant index method showed that the content of soil bioavailable As and Se extracted using 0.1 mol·L^(-1) KH_(2)PO_(4)-K_(2)HPO_(4) buffer solution had a significant positive relationship only with that of corn root(r=0.848 for As,P<0.01 and r=0.822 for Se,P<0.01).In conclusion,0.1 mol·L^(-1) KH_(2)PO_(4)-K_(2)HPO_(4) buffer solution could be used as an extractant to rapidly,accurately,and effectively extract bioavailable As and Se in soils.