The upwelling area in the Changjiang Estuary was selected to collect the core, where the red tide occurred frequently and hypoxic existed. The total organic carbon （TOC）, total nitrogen （TN）, biogenic silica （BSi...The upwelling area in the Changjiang Estuary was selected to collect the core, where the red tide occurred frequently and hypoxic existed. The total organic carbon （TOC）, total nitrogen （TN）, biogenic silica （BSi） and stable organic carbon isotopic ratios（δ13 Corg） were determined on the 210pb-dated sediment core. The concentrations of TOC, TN, BSi as well as their sedimentation fluxes have in- creased to some extent since the 1970s. TOC and TN fluxes increased about 45%, 36% respectively. The average δ13 Coorg value in the core was -23.67 ×10^-3 which remained nearly constant before the 20 century. The δ13 Corg values increased after the 1900s, two marked increases were observed from the 1950s and the 1970s. A simple δ13 Cors model was used to estimate the contribution of terrigenous and marine organic matter inputs for the sediment, which indicated the increase in accumulation since the 1970s has been almost exclusively marine. The increasing of marine organic matter accumulation （TOC, TN and BSi） was corresponding with the increasing of fertilizer consumption and the NO3-N budgets from the Changjiang River. The riverine runoff of fertilizers and nutrients stimulated the algae blooming. Enhanced primary production resulted in an enrichment of organic matter in the sediment. These data support the hypothesis that anthropogenic nutrient loading has been a significant factor on the eutrophication in the Changjiang Estuary.展开更多
Synthetic Ium manganate has been made in the laboratory at low temperature. The d-spaciug of which shows 1. 002 nm, 0. 501 nm and 0. 34 nm respectively. As the analogue of natural 1nm manganate, it has been used for ...Synthetic Ium manganate has been made in the laboratory at low temperature. The d-spaciug of which shows 1. 002 nm, 0. 501 nm and 0. 34 nm respectively. As the analogue of natural 1nm manganate, it has been used for a serieS of experiments of divalent cations substitution. The results indicate that the 1nm manganate has very strong cation substitution capacity, which probable is the reason of the valuable metal such as Cu, Ni and Co enriched in the manganese nodules. The preference of canons substituting into S 1nm manganate is Cu>Co>Zn≥Ni>Ca>Mg. In the manganese nodules, the content of Ni is usually higher than that of Cu and Co, but in the cation substitution, the latter two are more preference than the former. One can infer from this differentiation that the post-deposition cation substitution is not the sole mechanism by which the valuable metals enter the manganese nodules. It could be the results of combined effects of both original formation and the post-deposition substitution of canons,which leads to the enrichment of valuable metal in the manganese nodules.展开更多
基金The Zhejiang Provincial Science Foundation of China under contract No.Y506287the Youth Natural Science Foundation of State Oceanic Administration of China under contract No.200231Chinese Offshore Investigation and Assessment under contract Nos 908-01-ST04 and 908 -02-02-05
文摘The upwelling area in the Changjiang Estuary was selected to collect the core, where the red tide occurred frequently and hypoxic existed. The total organic carbon （TOC）, total nitrogen （TN）, biogenic silica （BSi） and stable organic carbon isotopic ratios（δ13 Corg） were determined on the 210pb-dated sediment core. The concentrations of TOC, TN, BSi as well as their sedimentation fluxes have in- creased to some extent since the 1970s. TOC and TN fluxes increased about 45%, 36% respectively. The average δ13 Coorg value in the core was -23.67 ×10^-3 which remained nearly constant before the 20 century. The δ13 Corg values increased after the 1900s, two marked increases were observed from the 1950s and the 1970s. A simple δ13 Cors model was used to estimate the contribution of terrigenous and marine organic matter inputs for the sediment, which indicated the increase in accumulation since the 1970s has been almost exclusively marine. The increasing of marine organic matter accumulation （TOC, TN and BSi） was corresponding with the increasing of fertilizer consumption and the NO3-N budgets from the Changjiang River. The riverine runoff of fertilizers and nutrients stimulated the algae blooming. Enhanced primary production resulted in an enrichment of organic matter in the sediment. These data support the hypothesis that anthropogenic nutrient loading has been a significant factor on the eutrophication in the Changjiang Estuary.
文摘Synthetic Ium manganate has been made in the laboratory at low temperature. The d-spaciug of which shows 1. 002 nm, 0. 501 nm and 0. 34 nm respectively. As the analogue of natural 1nm manganate, it has been used for a serieS of experiments of divalent cations substitution. The results indicate that the 1nm manganate has very strong cation substitution capacity, which probable is the reason of the valuable metal such as Cu, Ni and Co enriched in the manganese nodules. The preference of canons substituting into S 1nm manganate is Cu>Co>Zn≥Ni>Ca>Mg. In the manganese nodules, the content of Ni is usually higher than that of Cu and Co, but in the cation substitution, the latter two are more preference than the former. One can infer from this differentiation that the post-deposition cation substitution is not the sole mechanism by which the valuable metals enter the manganese nodules. It could be the results of combined effects of both original formation and the post-deposition substitution of canons,which leads to the enrichment of valuable metal in the manganese nodules.
