Accumulation of total CO₂ during stagnation in the Baltic Sea deep water and its relationship to nutrient and oxygen concentrations     

B. Schneider  G. Nausch  H. Kubsch  I. Petersohn 《Marine Chemistry》2002,77(4)

Accumulation of total CO₂ (C_T) was investigated in the sub-halocline deep water of the Gotland Sea (Baltic Sea) during a period of stagnation from 1995 to 1999. Depth profiles for C_T, nitrate, phosphate, and oxygen were measured during seven cruises in a grid consisting of 26 stations. The mean C_T increased by more than 60 μmol/kg from October 1995 to July 1999 corresponding to a mean accumulation rate of 1.1 mol/m² year. Taking into account vertical mixing, the vertical distribution of the C_T accumulation was used to determine mineralization rates at different depths. High rates immediately below the halocline indicated the existence of a fraction of organic matter, which is rapidly mineralized during sinking through the water column. A second fraction is more refractive and accumulates at the sediment surface in the deep center of the basin where it is slowly mineralized and partly buried. Phosphate release rates in anoxic waters and especially at the redoxcline were substantially higher than those estimated on the basis of the carbon mineralization and the Redfield C/P ratio. This is attributed to non-Redfield mineralization ratios and the dissolution of iron oxide/phosphate associates. The formation of nitrate by mineralization under oxic conditions was almost completely compensated by denitrification. Using the carbon mineralization rates and a C/N ratio of 8.4, a denitrification rate of 280 mmol/m² year was obtained, which approximately balances the input of nitrate/ammonia into the surface water. Relating the apparent oxygen utilization (AOU) to the C_T fraction that was generated by mineralization yielded a carbon mineralization/O₂ consumption ratio of 0.83.  相似文献   

海水中磷酸盐在固体粒子上阴离子交换作用──海水中磷酸盐-固体粒子相互作用的V形交换率-pH曲线     

赵宏宾  刘莲生  张正斌 《海洋与湖沼》1997,28(3):294-302

于1990年2月在青岛鲁迅公园采得海水样品；1989年5月在南京采得伊利石样品，在苏州采得高岭石样品；1990年3月实验室合成针铁矿和δ－MnO2样品。用振荡平衡实验、离心分离方法和光度分析方法测定3种电解质溶液（NaCL溶液、NaCl－ChCl2～溶液和海水）中磷酸盐在上述4种固体粒子上的交换率一PH曲线。测定结果表明，海水中磷酸盐在固体粒子上的交换率-PH曲线为V形，并建立阴离子液一固界面作用的交换率-PH公式；半定量地讨论V形交换率-PH曲线的形成机理，酸性溶液中，海水中腐殖酸和硫酸盐与磷酸盐竞争固体粒子上的作用点位，降低磷酸盐的液一固界面作用；碱性溶液中磷酸盐通过钙（Ⅱ）与固体粒子形成三元表面络合物，钙（Ⅱ）促进磷酸盐的液一固界面作用。海水中的钙（Ⅱ）、腐殖酸和硫酸盐是影响磷酸盐液一固界面作用的主要组分，酸性溶液中腐殖酸和硫酸盐降低磷酸盐在固体粒子上的交换作用，碱性溶液中钙（Ⅱ）会增加磷酸盐在固体粒子上的交换作用。  相似文献   

海水中磷酸盐在固体粒子上阴离子交换作用　海水中磷酸盐-固体粒子相互作用的台阶型等温线   总被引：4，自引：0，他引：4  

赵宏宾  刘莲生  张正斌 《海洋与湖沼》1997,28(2):172-178

通过研究氯化钠溶液中磷酸盐在４种固体粒子上的交换等温线及钙对上述交换等温线的影响，发现磷酸盐液－固界面作用的台阶型等温线，可用分级离子／配位子交换等温式定量描述，钙能够促进磷酸盐在针铁矿和δ－氧化锰上的交换作用，其机理是交换在固体粒子上的钙再结合溶液中的磷酸盐，形成表面无机三元络合物。  相似文献   

东山湾海水中活性磷酸盐的分布特征   总被引：1，自引：0，他引：1  

林峰  许清辉 《台湾海峡》1992,11(4):316-320

1988年5月、8月、11月和1989年2月东山湾海水中活性磷酸盐的浓度分别为0.10～0.55、0.02(未检出)～1.63、0.04～0.73和0.19～0.71μmol/L,平均值分别为0.23、0.34、0.38和0.50μmol/L。活性磷酸盐的分布特征和多无线性逐步回归的结果表明,活性磷酸盐浓度的主要影响因素随季节的不同而变化,其中1988年8月湾口和湾东侧区域明显受到上升流的影响。  相似文献   

Extent of immobilisation of phosphate during aeration of nutrient-rich, anoxic groundwater   总被引：1，自引：0，他引：1  

Jasper Griffioen 《Journal of Hydrology》2006,320(3-4):359-369

Nutrient-rich exfiltrating groundwater may impose a heavy phosphate load on surface water systems. However, iron oxides that bind PO₄ precipitate fast upon oxygenation at neutral pH and PO₄ may also become bound in Ca precipitates following upon pH increase, so load estimates based on conservative behaviour during exfiltration will be overestimates. Aeration experiments using natural groundwater were performed to characterise the immobilisation of PO₄ within one day after aeration started. Groundwaters having a wide variety in composition, were sampled in the coastal lowlands of the Western Netherlands. Three models were considered to describe the fast binding of PO₄ by Fe oxide type phases that form upon the oxygenation of dissolved Fe(II), each based on a different concept. The concepts were surface complexation, solid-solution precipitation and two-mineral precipitation. When the experimental data were compared with model results, all three models were found to be inadequate. Frequently, more immobilisation of PO₄ occurred than could be explained by binding to a Fe oxide type of phase alone. Uptake by Ca phosphates and/or Ca carbonates must additionally have played a role; alternatively, a non-ideal phase consisting of Ca, Fe and PO₄ precipitated upon oxygenation and CO₂ degassing. A predictive multiple regression model with two primary variables that reflect the driving forces for PO₄ immobilisation was deduced that describes immobilisation of phosphate after aeration of anoxic groundwater. The two primary variables are the log value of the groundwater Fe to PO₄ molar ratio and the saturation state for hydroxyapatite after the CO₂ degassing of groundwater. The model is useful for calculating the PO₄ load of surface water from exfiltration groundwater, taking into account fast immobilisation (<1 day) during exfiltration.  相似文献   

Determination of bioavailable Fe(III) content in column experiments with the reactive tracer phosphate     

Frank Dethlefsen  Rainer Meckenstock  Malte K. Veehmayer  Andreas Dahmke 《Environmental Geology》2004,46(6-7):896-904

Different methods were compared to evaluate the oxidation capacity of ferric iron in column studies. The specific adsorption of the reactive tracer phosphate on the Fe(III) oxide surface was used as an alternative approach to determine the oxidation capacity utilizing the linear correlation between the long-term extent of Fe(III) reduction and the specific surface area of the oxide. Although a low crystalline form of ferric iron (two-line ferrihydrite) was used as electron acceptor and toluene as a carbon source, only 31 and 24% respectively of the total iron was reduced by Geobacter metallireducens in parallel experiments. The results of the phosphate tracer tests were in good agreement with the Fe(III) that was actually reduced and the microbially oxidized toluene. The oxidation capacity of ferric iron is therefore overestimated by the chemical extraction methods, which completely dissolve the ferrihydrite and neglect surface-dependent limitations.  相似文献   

Effects of nitrate and phosphate on growth and C2 toxin productivity of Alexandrium tamarense CI01 in culture   总被引：1，自引：0，他引：1  

Da-Zhi Wang  Dennis P. H. Hsieh   《Marine pollution bulletin》2002,45(1-12)

Growth and C2 toxin productivity of a marine dinoflagellate, Alexandrium tamarense CI01 (ATCI01) which predominantly produces C2 toxin, were studied in unialgal batch cultures to optimize the concentrations of nitrate and phosphate for a maximal toxin yield. A range of start concentrations of the two major nutrients was determined in which algal growth was proportional to the nutrient concentrations used. The highest concentrations of nitrate and phosphate in this growth-enhancing range were 264 and 20 μM, respectively. In this concentration range, the C2 toxin yield (μg/l) and cellular toxin content (Qt, fmole per cell) reached a maximum at the lowest end of phosphate (5 μM) and the highest end of nitrate (264 μM). Further increase in the supply of nitrate continued to enhance the toxin yield. Our results indicated that the growth and toxin productivity of this algal strain in batch cultures had distinctly different optimal ranges of nitrate and phosphate concentrations. For a maximum toxin yield, a judicious use of phosphate under a nitrate-replete condition is called for.  相似文献   

Modal abundances of coarse-grained (>5 μm) components within CI-chondrites and their individual clasts – Mixing of various lithologies on the CI parent body(ies)     

《Chemie der Erde / Geochemistry》2019,79(4):125532

For the bulk rocks of CI chondrites, various values are given for the modal abundance of matrix (95–100 vol%) and the accompanying mineral constituents. Here, we have determined the modal abundance of phases >5 μm in the CI chondrites Orgueil, Ivuna, Alais, and Tonk. Considering this cut-off grain-size to distinguish between matrix and coarse-grained constituents, then, we find the modal abundance of the minor phases magnetite, pyrrhotite, carbonate, olivine, and pyroxene to be 6 vol% in total, and these phases are embedded within the fine-grained, phyllosilicate-rich matrix, making up 94 vol%. The values vary slightly from meteorite to meteorite. Considering all four chondrites, the most abundant phase is - by far - magnetite (4.3 vol%) followed by pyrrhotite (∼1.1 vol%). All four CI chondrites are complex breccias, and their degree of brecciation decreases in the sequence: Orgueil > Ivuna > Alais ∼ Tonk. Because these meteorites contain clasts with highly variable modal abundances, we therefore also studied individual clasts with high abundances of specific coarse-grained phases. In this respect, in Orgueil we found a fragment with a 21.5 vol% of magnetite as well as a clast having 31.8 vol% phosphate. In Ivuna, we detected an individual clast with a 21.5 vol% of carbonates. Thus, since the CI composition is used as a geochemical standard for comparison, one also should keep in mind that sufficiently large sample masses are required to reveal a homogeneous CI composition. Small aliquots with one dominating lithology may significantly deviate from the suggested standard CI composition.  相似文献   

Blast furnace slag can effectively remediate coastal marine sediments affected by organic enrichment     

Satoshi Asaoka 《Marine pollution bulletin》2010,60(4):573-578

There is an urgent need to control nutrient release fluxes from organically-enriched sediments into overlying waters to alleviate the effects of eutrophication. This study aims to characterize blast furnace slag (BFS) and evaluate its remediation performance on organically-enriched sediments in terms of suppressing nutrient fluxes and reducing acid volatile sulfide. BFS was mainly composed of inorganic substances such as CaO, SiO₂, Al₂O₃ and MgO in amorphous crystal phase. Container experiments showed that the phosphate concentration in the overlying water, its releasing flux from sediment and AVS of the sediment decreased by 17-23%, 39% and 16% compared to the control without BFS, respectively. The loss on ignition was significantly decreased by 3.6-11% compared to the control. Thus, the application of BFS to organically-enriched sediment has a suppressive role on organic matter, AVS concentration and phosphate releasing flux from sediments and therefore, is a good candidate as an effective environmental remediation agent.  相似文献   

Effects of nitrate and phosphate on growth and C2 toxin productivity of Alexandrium tamarense CI01 in culture   总被引：6，自引：0，他引：6  

Wang DZ  Hsieh D 《Marine pollution bulletin》2002,45(1-12):286-289

Growth and C2 toxin productivity of a marine dinoflagellate, Alexandrium tamarense CI01 (ATCI01) which predominantly produces C2 toxin, were studied in unialgal batch cultures to optimize the concentrations of nitrate and phosphate for a maximal toxin yield. A range of start concentrations of the two major nutrients was determined in which algal growth was proportional to the nutrient concentrations used. The highest concentrations of nitrate and phosphate in this growth-enhancing range were 264 and 20 μM, respectively. In this concentration range, the C2 toxin yield (μg/l) and cellular toxin content (Qt, fmole per cell) reached a maximum at the lowest end of phosphate (5 μM) and the highest end of nitrate (264 μM). Further increase in the supply of nitrate continued to enhance the toxin yield. Our results indicated that the growth and toxin productivity of this algal strain in batch cultures had distinctly different optimal ranges of nitrate and phosphate concentrations. For a maximum toxin yield, a judicious use of phosphate under a nitrate-replete condition is called for.  相似文献