黄河内蒙古段干流沉积物中砷含量及形态研究

Concentration and Species of Arsenic in the Yellow River Sediments in Inner Mongolia Section

为探明黄河内蒙古段沉积物中砷含量及形态分布特征，采集黄河内蒙古段干流柱状沉积物，采用 HNO4－H2 SO4－HClO4法消解沉积物样品，提取沉积物中吸附型砷（A－As）、铝型砷（Al－As）、铁型砷（Fe－As）、钙型砷（Ca－As）、包蔽型砷（O－As）5种形态砷，并采用氢化物发生原子荧光分光光度法测定砷含量。结果表明：黄河内蒙古段干流柱状沉积物中砷含量为7．123～16．661 mg／kg，平均为9．292 mg／kg；从整体上看，左岸沉积物砷含量高于右岸，随深度增加砷含量呈下降趋势，从上游至下游砷含量在黑柳子段出现高值；黄河内蒙古段沉积物中砷以Ca－As为主，O－As次之；随着深度的增加，总体上，Ca－As含量略有升高，A－As和O－As含量有所下降，Al－As和Fe－As含量基本不变。

Concentration and species distribution of arsenic in the Yellow River sediment cores in Inner Mongolia section were researched. Sediment was digested by HNO4 -H2 SO4 -HClO4 ,arsenic in sediments was divided into five fractions such as A-As、Al-As、Fe-As、Ca-As and O-As and extracted by sequential extraction procedure. Arsenic concentrations were determined by hydride generation atomic flu-orescence spectrophotometry. The results show that the total arsenic concentrations is 7. 123-16. 661 mg/kg,averagely 9. 292 mg/kg. Loo-king from the whole,arsenic concentration of the left bank is higher than those of the right bank. Arsenic concentration in sediment is de-creased with the increase of depth and reaches the highest level at Heiliuz along the river. Arsenic in the sediments is mainly in Ca-As and secondly in O-As. With the increase of depth,the percentage of Ca-As is increased slightly,the percentage of A-As and O-As is de-creased,Al-As and Fe-As are basically unchanged.