Mn-oxide: a major source of easily mobilisable Co and Ni under reducing conditions in New Caledonia FerralsolsLes oxydes de Mn : une source majeure de Co et Ni facilement mobilisables en conditions réductrices dans les Ferralsols de Nouvelle-Calédonie     

Cécile Quantin  Thierry Becquer  Jacques Berthelin 《Comptes Rendus Geoscience》2002,334(4):273-278

Chemical and bacterial reduction and dissolution of Fe and Mn-oxide and the concomitant solubilisation of Co and Ni were studied in a surface horizon of a New-Caledonia Ferralsol. Chemical extractions showed that Mn and Co were in a large part associated in Mn-oxides. The main part of Ni was associated with goethite, but a very small fraction was also associated with Mn-oxides. Anaerobic reducing bacterial activity was responsible for Fe solubilisation at a smaller extent than for Mn solubilisation and consequently for associated metal release. Submicroscopic investigations revealed the presence of a Mn-oxide containing Co, Ni and Al, close to a lithiophorite–asbolane mixed-layers Mn-oxide, which can be considered as a main source of easily available metals in this soil. To cite this article: C. Quantin et al., C. R. Geoscience 334 (2002) 273–278.  相似文献   

Acceleration of Selenate Reduction by Alternative Drying and Wetting of Soils   总被引：1，自引：0，他引：1  

朴河春  刘广深等 《中国地球化学学报》1996,15(3):278-284

In nature selenate reduction and nitrate denitrification both follow a similar biogeo-chemical mechanism.It has been proved that abiotic stresses such as alternative drying and wetting can exert an important influence on nitrate denitrification as well as on selenate reduction.Our experimental results lend great support to the above conclusion.  相似文献   

湖泊中磷的循环与沉积作用   总被引：5，自引：1，他引：5  

东野脉兴 《化工矿产地质》1996,18(4):258-262

地壳存在大量微溶性磷酸盐矿物，是湖泊中无限的磷源。中国云南省的滇池周围分布着大量早寒武世梅树村期磷块岩，其可溶性大于内生磷灰石，因此滇池湖水中磷的浓度提高，达０．０４～０．３８ｍｇ／Ｌ，是一般湖水中磷浓度的４～１０倍。藻类与细菌在滇池大量繁殖，摄取磷等营养物质，死亡后又被分解生成可溶性颗粒有机磷，磷质又返回湖水中，而那些分解后的水溶部分、不易分解的顽性组分或者不能为后来的生物所利用的组分，形成泥状沉积物或有机泥浆沉入湖底加入湖相沉积物。  相似文献   

与细菌活动有关的成矿作用——两个欧洲铅锌矿床实例   总被引：4，自引：0，他引：4  

胡明安 《矿床地质》1997,16(1):61-70

法国布·玛和西班牙拉·弗矿床分别产于富含干酪根的白云岩和沥青的铁质白云岩中。正构烷、烷基环已烷、藿烷和甾烷等生物标志化合物研究揭示了成矿时发生过细菌活动。细菌在沉积－成岩早期发育于还原水体中，或在成岩期－成岩期后由大气降水自地表带来，其赖以生存的有机质既可以是生物聚合体（布·玛矿床），亦可以是地质聚合体（拉·弗矿床）。这些微生物在１００℃以下的温度条件下生存繁殖，使硫酸盐还原生成硫化氢，导致铅锌硫化物沉淀  相似文献   

Role of Bacteria in the Carbon and Nitrogen Flow between Water-Column and Sediment in a Shallow Marine Bay (Bay of Piran, Northern Adriatic Sea)   总被引：2，自引：0，他引：2  

G. J. Herndl    J. Faganeli    N. Fanuko    P. Peduzzi  V. Turk 《Marine Ecology》1987,8(3):221-236

Abstract. The interdependences between phytoplankton standing crop, bacterial biomass and the dissolved organic matter (DOM) pool in the water column were investigated and related to sediment parameters in a shallow marine bay (Bay of Piran, Northern Adriatic Sea) over an annual cycle. Bacterioplankton density varied between 1–10 × 10⁵ cells ml^-1, with lowest density observed in March corresponding to the low Chi a concentrations during this period. Generation times as determined by dialysis incubations ranged between 4h (June) and 82 h (March). Mean bacterial secondary production rates during summer were about 40 mg C m^-1 d^-1 and 5mg C m^-3.d^-1 during winter. With a short time lag, DOM concentrations followed the fluctuation in Chi a.
Sediment oxygen demand measurements revealed a mean mineralization rate of about 260 mg C m^-2 d^-1 during summer and 100–200 mg C m^-2 d^-1 in winter. Sediment bacterial density varied between 10⁸ - 10⁹ cells g (sediment dry wt)^-1 in the top 5 cm sediment layer or, in terms of biomass, 4.3 g C m^-l during summer and 0.6 g C m^-2 during winter. Highest concentrations of DOM in pore waters were measured in September, coinciding with high rates of sediment oxygen demand.  相似文献   

海洋细菌对钢的腐蚀作用     

徐怀恕  纪伟尚  胡锡钢  宋庆云 《中国海洋大学学报(自然科学版)》1989,(1)

从青岛港钢板桩的锈层中分离到三种腐蚀性细菌。经鉴定这三种细菌是氧化硫杆菌(Thiobacillus thiooxidans),排硫杆菌(Thiobacillus thioparus)和脱硫脱硫弧菌(Desulfovib-iodesulforicans)。用失重法测定了这三种细菌对四种钢样的腐蚀速率。氧化硫杆菌的腐蚀速率为53.5m.d.d.(毫克/平方分米/天)(BJ_2),83.3(902),121.8(CXL-4)和81.0(7~#)。排硫杆菌的腐蚀速率为23.6mdd(BJ_2)。脱硫脱硫弧菌的腐蚀速率为9.9m.d.d.(BJ_2),9.2(902),3.7(CXL-4)和2.9(7~#)。这三种细菌对钢都具有很强的腐蚀能力。  相似文献   

Basin-Scale Geographic Patterns of Bacterioplankton Biomass and Production in the Subarctic Pacific, July–September 1997     

Toshi Nagata  Rumi Fukuda  Hideki Fukuda  Isao Koike 《Journal of Oceanography》2001,57(3):301-313

Bacterial biomass and production rate were measured in the surface (0–100 m) and mesopelagic layers (100–1,000 m) in the subarctic Pacific and the Bering Sea between July–September, 1997. Depth profiles were determined at stations occupied in oceanic domains including the subarctic gyres (western, Bering Sea, and Gulf of Alaska) and a boundary region south of the gyres. In the surface layer (0–100 m), both bacterial biomass and production were generally high in the western and Bering Sea gyres, with the tendency of decrease toward east. This geographic pattern was consistent with the dominant regime of phytoplankton biomass at the time of our survey. A significant portion of variation in bacterial production was explained by the concentration of chlorophyll a (r ² = 0.340, n = 60, P < 0.001) and, to the greater extent, by the concentration of semilabile total organic carbon (SL-TOC = TOC at a given depth—TOC at 1,000 m, r ² = 0.488, n = 59, P < 0.0001). Temperature significantly improved the regression model: temperature and chlorophyll jointly explained 60% of variation in bacterial production. These results support the hypothesis that bacteiral growth is largely regulated by the combination of temperature and the supply of dissolved organic carbon in subarctic surface waters. In the mesopelagic layer (100–1,000 m), the geographic pattern of bacterial production was strikingly different from the surface phytoplankton distribution: the production was high in the boundary region where the phytoplankton biomass was lowest. Bacterial growth appeared to be largely controlled by the supply of organic carbon, as indicated by the strong dependency of bacterial production on SL-TOC (r ² = 0.753, n = 75, P < 0.0001). The spatial uncoupling between surface phytoplankton and mesopelagic bacterial production suggests that the supply rate of labile dissolved organic carbon in the mesopelagic zone does not simply reflect the magnitude of the particulate organic carbon flux in the subarctic Pacific.  相似文献   

Nitrogen and oxygen isotopic composition of N₂O from suboxic waters of the eastern tropical North Pacific and the Arabian Sea—measurement by continuous-flow isotope-ratio monitoring     

T. Yoshinari  M. A. Altabet  S. W. A. Naqvi  L. Codispoti  A. Jayakumar  M. Kuhland  A. Devol 《Marine Chemistry》1997,56(3-4)

Nitrous oxide (N₂O) is a trace gas that is increasing in the atmosphere. It contributes to the greenhouse effect and influences the global ozone distribution. Recent reports suggest that regions such as the Arabian Sea may be significant sources of atmospheric N₂O.In the ocean, N₂O is formed as a by-product of nitrification and as an intermediary of denitrification. In the latter process, N₂O can be further reduced to N₂. These processes, which operate on different source pools and have different magnitudes of isotopic fractionation, make separate contributions to the ¹⁵N and¹⁸O isotopic composition of N₂O. In the case of nitrification in oxic waters, the isotopic composition of N₂O appears to depend mainly on the ¹⁵N/¹⁴N ratio of NH⁺₄ and the ¹⁸O/¹⁶O ratio of O₂ and H₂O. In suboxic waters, denitrification causes progressive ¹⁵N and ¹⁸O enrichment of N₂O as a function of degree of depletion of nitrate and dissolved oxygen. Thus the isotopic signature of N₂O should be a useful tool for studying the sources and sinks for N₂O in the ocean and its impact on the atmosphere.We have made observations of N₂O concentrations and of the dual stable isotopic composition of N₂O in the eastern tropical North Pacific (ETNP) and the Arabian Sea. The stable isotopic composition of N₂O was determined by a new method that required only 80–100 nmol of N₂O per sample analysis. Our observations include determinations across the oxic/suboxic boundaries that occur in the water columns of the ETNP and Arabian Sea. In these suboxic waters, the values of δ¹⁵N and δ¹⁸O increased linearly with one another and with decreasing N₂O concentrations, presumably reflecting the effects of denitrification. Our results suggest that the ocean could be an important source of isotopically enriched N₂O to the atmosphere.  相似文献   

Benthic Denitrification in the Gulf of Bothnia   总被引：1，自引：0，他引：1  

A. Stockenberg  R.W. Johnstone 《Estuarine, Coastal and Shelf Science》1997,45(6):835-843

Denitrification was measured over an 8-month period in the Bothnian Bay and the Bothnian Sea, the two northernmost basins of the Baltic Sea. The recorded rates varied between 0 and 0·94 mmol N m⁻²day⁻¹. In the Bothnian Sea, a seasonal pattern could be discerned with high rates in spring, no rate in summer and a moderate rate in winter. In the Bothnian Bay, no such seasonality was observed. It is suggested that denitrification in the Gulf of Bothnia is regulated by sediment nitrification. Calculation of annual mean rates of denitrification gave that the amount of nitrogen consumed by denitrification corresponded to 1·45×10⁴tons N year⁻¹for the Bothnian Bay and 3·45×10⁴tons N year⁻¹for the Bothnian Sea. A comparison with total N input (river runoff, point sources and atmospheric deposition) to the two basins showed that the proportion of N removed through denitrification amounted to 23% for the Bothnian Bay and 31% for the Bothnian Sea.  相似文献   

Remineralization and accumulation of organic carbon and nitrogen in marine sediments of eutrophic bays: the case of the Bay of Concepcion, Chile     

Laura Farías   《Estuarine, Coastal and Shelf Science》2003,57(5-6):829-841

The Bay of Concepcion (36°40′S; 73°02′W) is a semi-enclosed and shallow embayment in which biogeochemical processes are seasonally coupled to coastal upwelling during the austral spring and summer. The nutrient cycle in the bay is complex due to the combined effects of a pronounced O₂ minimum layer and high nutrient concentrations both originating from subsurface equatorial water during coastal upwelling and a rapid rate of sediment nutrient recycling. The sediments are characterized by a high content of organic matter mainly due to the extremely high rates of phytoplankton production and deposition. During the upwelling period, a black flocculent layer frequently covers the sediment–water interface in the inner part of the bay where an extensive mat of Beggiatoa spp. develops. Three approaches are used to analyse the extent to which the benthic system recycles or retains nutrients at two stations, located at the centre (station C, St. C) and mouth (station B, St. B) of the bay for a 1-year period (March 1996–1997): (1) estimation of C and N remineralization rates based on SO₄²⁻ reduction measurements, (2) calculation of C and N turnover rates using a diagenetic model applied to total organic carbon and total nitrogen vertical distributions and, (3) construction of C and N budgets from direct measurements of sedimentation (from a sediment trap) and estimates of the C and N burial rates. Depth-integrated SO₄²⁻ reduction rates varied between 3.4 (winter) and 25.5 (summer) mmol m⁻² d⁻¹. Estimated C and N oxidation rates ranged between 7.9 and 87.8 mol C m⁻² yr⁻¹ and between 0.9 and 6.9 mol N m⁻² yr⁻¹, respectively. Each approach yielded minor differences in the C and N remineralization rates (and also minor differences between both studied stations), except when the kinetic model was applied to C and N distribution without including the presence of the flocculent layer. The rates of carbon oxidation and sulphate reduction were considerably higher than in other coastal sediments with similar depositional regime. The C and N burial rates were 2.23 and 0.21 (St. C) and 1.30 and 0.09 (St. B) mol m⁻² yr⁻¹, respectively. The C/N ratio of the buried fraction was ca. 10.6 at St. C and 14.4 at St. B. Because the observed differences in burial rates could not be ascribed to distinctive depositional (both stations have similar sediment accumulation rates) and oceanographic (similar O₂ concentration and hydrography) conditions, differences may be due to in part spatial heterogeneity in the supply of organic matter. The degree of preservation of organic matter as plankton detritus and nitrogen accumulating bacterial biomass associated with Beggiatoa spp. at St. C may also be involved.  相似文献