长江口潮滩植物对沉积物铁的地球化学循环及磁性特征的影响

通过长江河口高潮滩芦苇带沉积物柱状样CYLWA 1活性铁、有机质、粒度分析及磁性测量,探讨潮滩植物对沉积物铁的地球化学循环及磁性特征变化的影响。结果显示,沉积物柱状样总体上以Fe2 + 占优势,且含量随深度逐渐增加。但在亚表层 (10～ 2 0cm),由于根系的释氧作用,存在着以Fe3 + 占优势的氧化层。在 10～ 2 0cm这一氧化层,指示细颗粒磁性矿物的参数 (χ_fd、χ_ARM)明显减小,而反映磁性矿物类型的参数 (B_CR、SIRM/ χ)显著增大,指示了亚铁磁性矿物颗粒变粗,不完整反铁磁性矿物明显富集,这一现象反映了氧化层不完整反铁磁性矿物的相对富集

Influence of Plant on Geochemical Cycling of Iron and the Magnetic Properties of Intertidal Sediments in the Yangtze Estuary

One core (CYLWA-1) from Phragrmites australis vegetated tidal flat, the Yangtz e Estuary, is selected to investigate the effect of plant on geochemical cycling o f iron and the magnetic properties of the sediments. The results show that Fe 2+ dominates in most layers of the sediments and increases with depth, except at a depth of 14～20 cm, where Fe3+ dominates due to the abundant distribution of live roots. In the oxidized layer of 14～20 cm, χ _fd, χ _ARM and χ _ARM /SIRM decline, sug gesting coarsening of ferrimagnetic minerals. On the contrary, the obvious incre ase in B _CR and SIRM/ χ indicates relative increase of imperfect an ti-ferromagneti c minerals. It is suggested that ferrimagnetic minerals be transformed into impe rfect anti-ferromagnetic iron oxides under oxidizing environment.