黄河干流表层沉积物铁形态的分布特征及相关性分析

应用颗粒物中铁的连续浸提技术研究了黄河干流表层沉积物中铁形态的分布特征及相关性,研究结果表明:表层沉积物中总铁(∑Fe)含量范围在14.01~30.98g/kg,最小值和最大值分别出现在黄河柳林段(H13)和渤海近海(H21);各形态铁中以残渣态(Fe-6)含量最高,占∑Fe比率92.55%~98.44%,有效态铁(BFe)含量仅占1.56%~6.98%,与∑Fe呈现显著正相关,并且三者含量高低沿程变化趋势一致;有机质(OM)与BFe、铁锰氧化物态铁(Fe-4)呈现显著正相关系,BFe与Fe-4呈现极显著正相关系,说明BFe含量主要受Fe-4和有机质的控制;黄河水体总颗粒物(TPM)浓度增高,如黄河中游大禹渡段H15和三门峡段H17,表层沉积物∑Fe与Fe-1含量高,TPM浓度降低,如黄河上游乌海段H7和三盛公段H8,表层沉积物∑Fe与Fe-1含量低,说明黄河流域广泛的人工筑坝,导致水体TPM浓度改变,对黄河铁循环产生了不可忽视的影响.

Distribution characteristics and correlation analysis of Fe speciation in the surface sediments from different reaches along Yellow River

The distribution characteristics and correlation analysis of Fe speciation in the surface sediments from different reaches along Yellow River have been analyzed utilizing the so-called sequential extraction approach. The results indicate that the concentration of total iron (∑Fe) in the surface sediments is in the range from 14.01g/kg to 30.98 g/kg, Liulin (H13) sample is the maximum and Bohai offshore (H21) sample is the minimum. The residue iron(Fe-6)-the highest concentration in all speciations with 92.55%~98.4% of ∑Fe, and the bio-available fraction iron (BFe) only for 1.56%~6.98% with remarkably positive correlation with ∑Fe, the change trades of BFe, Fe-6 and ∑Fe concentrations are consistency along main stream of the Yellow River. The organic matter (OM) shows a notable correlation with both BFe and Fe-Mn oxides (Fe-4), while BFe has extremely positive correlation with Fe-4, indicating that the content of BFe mainly relies on the Fe-4 and the organic matter. When the concentration of total particulate matter (TPM) is increased in the water of the Yellow River, such as in the middle reaches of the Yellow River Dayudu segments (H15) and Sanmenxia segments (H17), one can find the high concentration of ∑Fe and Fe-1 in the surface sediments, when the concentration of TPM decrease, such as in the upper reaches of the Yellow River Wuhai segments (H7) and Sanshenggong segments (H8) , the concentration of ∑Fe and Fe-1 in the surface sediments is low. The results indicate that the artificial dams in the Yellow River Basin cause the changes of TPM concentration in the water, and also lead to non negligible impact on the iron cycle in the Yellow River.