A sediment core H9 collected from the middle of the Okinawa Trough was studied by sequential leaching to indentify the hy- drothermal component from the various other components such as detrital, biogenic, and so on. ...A sediment core H9 collected from the middle of the Okinawa Trough was studied by sequential leaching to indentify the hy- drothermal component from the various other components such as detrital, biogenic, and so on. The elements were partitioned into five fractions： exchangeable, bound to carbonates, bound to iron and manganese oxides, bound to organic matter, and re- sidual. The contents of elements A1, Ti, K, Fe, Mn, Pb, Co, Cu, Ni, and V in each fraction were determined and their percent- ages were calculated. Residual fraction is a dominant speciation for most studied elements except for Mn and Pb in the core sediments. For the elements A1, Ti, and K, residual fraction accounts for more than 95% of the total metal concentration. The concentrations of all studied elements in the exchangeable fraction, carbonate fraction, and organic fraction are relatively low. The metal levels in the iron and manganese oxide fraction are relatively high and this fraction represents another prevalent speciation. Also in this fraction, the metal concentrations and percentages are higher in the core section above 80 cm than those below 80 cm. Especially for Mn and Pb, the fractions bound to iron and manganese oxides account for more than 50% of the total metal concentration for the upper 80 cm section. Hydrothermal components mainly occur in this fraction. And the downcore variations of metal contents and percentages reflect the variations of hydrothermal inputs to the sediments. The high metal levels in the upper core indicate the enhancing influence of hydrothermal activities around on the core H9 during its late stage of sedimentation. The accumulation rates of hydrothermally derived Fe, Mn, Pb, Co, Cu, Ni, and V were evaluated based on their concentrations in the iron and manganese oxide fractions in this study. The results show that the accumulation rate of hydrothermally derived Mn is similar to those obtained from the Mid-ocean Ridges and Lau Basin. However, hydrothermally derived Fe and Cu present a relatively lower l展开更多
A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can ...A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can reach up to 95.9%,82.1%,68.3%,93.3%,82.3%,96.9%,98.3%and 95.6%,respectively,under the optimal condition in the leaching process.Aliquat 336 showed excellent extraction performance of iron in chloride-rich solution,and the maximum extraction efficiency can reach over 96%in one time extraction while the loss of other metals was less than 10%,under the condition of Aliquat 336 concentration(v/v)of 30%,aqueous-organic ratio of 1.0 and extraction time of 20 min.Furthermore,P204 can effectively extract the scandium while Al and most other REEs remain in the aqueous phase.This approach may provide a new insight for the recovery of valuable resources from red mud.展开更多
Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer(BF) on soil nutrient leaching in agricultural so...Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer(BF) on soil nutrient leaching in agricultural soils. We conducted a soil column leaching experiment to study the effects of BF on the leaching of total nitrogen(TN), total phosphorus, and total potassium(TK) in tobacco soils. The distribution characteristics of NH_4^+-N, available P, and available K in soil profiles were analyzed after the application of BF. Biochar was prepared by pyrolysis of fluecured tobacco stems. It was applied at four levels, 0%, 3%,9%, and 15%(w/w), respectively, to the compound fertilizer. Compared with the control, the leaching loss of soil TN decreased by 8.36%, 6.72%, and 6.45%, and the loss of soil TK decreased by 9.18%, 9.31% and 11.82% in the 3%,9%, and 15% BF treatments, respectively. However, BF had no significant effect on the P leaching due to the low movement of P in the soil profile. In addition, the BF addition increased the immobilization of NH_4^+-N, available P, and available K in the soil profile. These results indicate that addition of BF to a tobacco-planting soil reduced nutrient leaching, and suggest that BF could be an effective method of applying biochar to agriculture fields.展开更多
基金supported by National Natural Science Foundation of China (Grant No.40306009)
文摘A sediment core H9 collected from the middle of the Okinawa Trough was studied by sequential leaching to indentify the hy- drothermal component from the various other components such as detrital, biogenic, and so on. The elements were partitioned into five fractions： exchangeable, bound to carbonates, bound to iron and manganese oxides, bound to organic matter, and re- sidual. The contents of elements A1, Ti, K, Fe, Mn, Pb, Co, Cu, Ni, and V in each fraction were determined and their percent- ages were calculated. Residual fraction is a dominant speciation for most studied elements except for Mn and Pb in the core sediments. For the elements A1, Ti, and K, residual fraction accounts for more than 95% of the total metal concentration. The concentrations of all studied elements in the exchangeable fraction, carbonate fraction, and organic fraction are relatively low. The metal levels in the iron and manganese oxide fraction are relatively high and this fraction represents another prevalent speciation. Also in this fraction, the metal concentrations and percentages are higher in the core section above 80 cm than those below 80 cm. Especially for Mn and Pb, the fractions bound to iron and manganese oxides account for more than 50% of the total metal concentration for the upper 80 cm section. Hydrothermal components mainly occur in this fraction. And the downcore variations of metal contents and percentages reflect the variations of hydrothermal inputs to the sediments. The high metal levels in the upper core indicate the enhancing influence of hydrothermal activities around on the core H9 during its late stage of sedimentation. The accumulation rates of hydrothermally derived Fe, Mn, Pb, Co, Cu, Ni, and V were evaluated based on their concentrations in the iron and manganese oxide fractions in this study. The results show that the accumulation rate of hydrothermally derived Mn is similar to those obtained from the Mid-ocean Ridges and Lau Basin. However, hydrothermally derived Fe and Cu present a relatively lower l
基金Project(21707167)supported by the Natural Science Foundation of China
文摘A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can reach up to 95.9%,82.1%,68.3%,93.3%,82.3%,96.9%,98.3%and 95.6%,respectively,under the optimal condition in the leaching process.Aliquat 336 showed excellent extraction performance of iron in chloride-rich solution,and the maximum extraction efficiency can reach over 96%in one time extraction while the loss of other metals was less than 10%,under the condition of Aliquat 336 concentration(v/v)of 30%,aqueous-organic ratio of 1.0 and extraction time of 20 min.Furthermore,P204 can effectively extract the scandium while Al and most other REEs remain in the aqueous phase.This approach may provide a new insight for the recovery of valuable resources from red mud.
基金supported by the National Natural Science Foundation of China (Nos. 41773144 U1612441+5 种基金 41503080)the Key Technologies R&D Project in Agriculture of Guizhou province (Nos. NY [2013] 3019 NY [2015] 3001-1)the Major S&T Special Project of Guizhou province (No. [2014] 6015-21)the Opening Fund of the State Key Laboratory of Environmental Geochemistry (SKLEG2018905)Innovative Plan of Guizhou province and the Science and Technology Project of Guizhou Tobacco Company (201614)
文摘Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer(BF) on soil nutrient leaching in agricultural soils. We conducted a soil column leaching experiment to study the effects of BF on the leaching of total nitrogen(TN), total phosphorus, and total potassium(TK) in tobacco soils. The distribution characteristics of NH_4^+-N, available P, and available K in soil profiles were analyzed after the application of BF. Biochar was prepared by pyrolysis of fluecured tobacco stems. It was applied at four levels, 0%, 3%,9%, and 15%(w/w), respectively, to the compound fertilizer. Compared with the control, the leaching loss of soil TN decreased by 8.36%, 6.72%, and 6.45%, and the loss of soil TK decreased by 9.18%, 9.31% and 11.82% in the 3%,9%, and 15% BF treatments, respectively. However, BF had no significant effect on the P leaching due to the low movement of P in the soil profile. In addition, the BF addition increased the immobilization of NH_4^+-N, available P, and available K in the soil profile. These results indicate that addition of BF to a tobacco-planting soil reduced nutrient leaching, and suggest that BF could be an effective method of applying biochar to agriculture fields.
