Comparative Study on the Characteristics of Reactive Iron and Manganese in Sediments From Coastal China and Its Significance for Organic Carbon Mineralization:Case Studies at the Yangtze River Esturary,the Mud Area of the Shelf in Central Yellow Sea,and th
The early diagenesis of iron and manganese is one of the important pathways of organic carbon mineralization in marine sediments.The details of content and distribution of reactive iron(Fe)and manganese(Mn)are of great significance to evaluating organic carbon mineralization contributed by dissimilatory Fe and Mn reduction in sediments.However,so far,few studies have investigated the distribution of reactive iron and manganese in different sedimentary environments of coastal China.The molality of reactive Fe and Mn in sediments from the Yangtze River Estuary(CJK1-3),the mud area of the shelf in central Yellow Sea(YSCW-1)and Yellow River Estuary(NS-37)was investigated based on the sequential extraction procedures in this study.The relevant biogeochemical analysis was conducted with the depth profiles of Fe and Mn in the sediment gravity cores.Results showed that the mean molality of carbonate-bound iron(Fecarb)in sediments from the Yangtze River Estuary was 4.71 times and 6.45 times higher than that from the mud area of the shelf in central Yellow Sea(19.35 μmol·g-1,dry weight)and Yellow River Estuary(14.15 μmol·g-1,dry weight),respectively.The mean value of amorphous and poorly crystalline Fe(III)oxides(Feox1)showed the following decreading trend,CJK1-3(111.63 μmol·g-1,dry weight)>YSCW-1(79.99 μmol·g-1,dry weight)>NS-37(61.63 μmol·g-1,dry weight).The molality of Mn oxides was lower than that of iron in all three stations,and the mean molality of reducible manganese(Mnre)accounted for 1.56%,0.91%and 2.29%of Feox1,respectively.The results of the incubation experiment showed that dissimilatory Fe and Mn reduction occurred under the condition of in-situ organic matter.The evaluation results of dissimilatory Fe and Mn reduction indicated that dissimilatory Fe reduction was a major pathway for organic carbon mineralization in coastal(Estuary)sediments,while Mn reduction was a minor one.The results of this study provide some new insights for iron and manganese biogeochemistry in coastal(estuarine)sediments of China.
Yangtze River EstuaryYellow SeaYellow River Estuaryironmanganeseorganic carbon
万方数据
维普
