厦门港滩涂沉积物中铁、锰的早期化学成岩过程

Early Chemical Diagenesis of Iorn,Manganese in Coastal Sediment of Xiamen Harbour

研究了厦门港滩涂沉积物铁锰的化学过程.测定了不同季节沉积物柱样的孔隙度、间隙水盐度、氧化还原电位(E_(pt))、Mn^(2+)、Fe^(2+)的垂直分布,显示了滩涂沉积物由于泥沙的不均匀分布和分带性以及陆源淡水的不规则渗入导致Fe、Mn的化学成岩作用比较复杂;沉积物柱样的多数层次处于中等还原性,间隙水Mn^(2+)在表面层(0～2cm深度)无季节差别出现最高值(E_(pt)下降梯度最大),深于2cm层Mn^(2+)随深度大幅度下降;间隙水Fe^(2+)与Mn^(2+)具有类似的变化趋势,且随着沉积物还原性的增加.MnO_2和Fe_2O_3先后还原与其过程自由能的卞降次序一致.

The diagenetic chemical processes of Iorn,Manganese were studied forcoastal sediment in Xiamen Harbour. We measured the porosity pore water salinity,redox po tential (Ept. )and the vertical distribution of Mn2+ and Fe2+ for the Sediment column in different seasons. The results proclaimed that the chemical diagenesis of Iorm, Manganese were complicated by the uneven distribution and different zores of silt and by the irregular percolating of continental fresh water. Most gradations of sediment column were middle reducibili-ty. The maximum value appeared and did not change with seasons for pore water Mn2+ in the 0-2 em layer(Ept degrease with Maximum gradient). Mn2+degrease extensively with depth below 2 cm layer. Pore water Fe2+ and Mn2+ changes with the similar tendency. Increasing reducibility in sediment column,MnO2 was reduced first than Fe2O3. The sequence was consistent with that of Gibbs' free energy degreasing.