污染河流沉积物锑释放规律的研究

Antimony Release From the Sediments of the Antimony-polluted River

为了研究锑污染河流水化学环境条件对沉积物锑释放的影响,进行了锑矿区下游河流沉积物样品的特性表征及环境条件(pH、盐度和腐植酸质量浓度)对锑释放影响规律的研究.首先对沉积物样品进行了物相、傅里叶变换红外光谱(FTIR)和X线荧光光谱分析,并开展了不同pH、盐度和共存腐植酸质量浓度下锑的释放量及释放动力学实验.表征分析结果表明:所采集的沉积物样品矿物相、表面官能团、主要元素含量等特性相似;沉积物中主要含有石英石、斜长石、云母、斜磷锰矿和方解石,主要金属含量顺序均为Si>Al>Fe>Ca>K>Mg>Mn.模拟环境条件影响的批式实验结果表明:随着pH降低、盐度升高和腐植酸质量浓度增大,锑释放均呈增加趋势,其中pH对锑释放影响最大;pH对沉积物/锑酸盐作用的影响是样品所含矿物溶解释放锑和矿物表面荷电特性改变吸附Sb(OH)6-/H3SbO3能力变化两方面综合平衡的结果;在pH=3.0时,沉积物锑释放量与沉积物表面Mn元素显著相关,推测样品斜磷锰矿的含量及其溶解显著地影响锑的释放,矿物(主要是斜磷锰矿)溶解比表面吸附对锑的释放影响更大.

To investigate the effect of aquatic chemistry on antimony release from Sb-contained sediments, samples from the down-stream of an antimony-polluted reviver were characterized. Their X-ray diffraction patterns, Fourier transform infrared spectroscopy （FTIR） spectra and X-ray fluorescence spectra were collected. Moreover, the effect of pH, sality and concentrations of humic acids on the release of antimony were also investigated. Results show that all sediment samples contained similar mineral phases, surface groups and similar main element contents. Identified phases include quartz, albite, muscovite, calcite and stewartite. Elements at the surface of the sediments follow the order of Si 〉 A1 〉 Fe 〉 Ca 〉 K 〉 Mg 〉 Mn. Batch release experiments show that the amounts of released antimony increase with decreasing pH, increasing concentrations of salinity and humic acids, pH is the most important factor to affect antimony release. The release is caused by pH-related mineral dissolution and desorption, and the final states are an equilibrium of the both processes. At pH = 3, the released antimony is positively correlated to the contents of Mn at the surface of sediments. That means that dissolution of stewartite rather than surface adsorption markedly affected the release of antimony.