Bacterial sulphate reduction in sediments of a european salt marsh: Acid-volatile and tin-reducible products     

D. B. Nedwell  S. Takii 《Estuarine, Coastal and Shelf Science》1988,26(6)

The products of ³⁵S-sulphate reduction by sedimentary bacteria were measured at two sites in a salt marsh on the east coast of England. Non-acid-volatile products were measured, after acid-volatile sulphide was removed, by their reduction to sulphide by digestion with tin. The proportion of the sulphate reduced to tin-reducible products varied between 25% in a salt marsh pan and 61% in creek sediment, over a 0–25 cm depth profile. There were also variations with depth at each site in the proportions of sulphate reduced to tin-reducible products. Further examination revealed differences in the proportions of sulphate which were reduced to free sulphide, acid-volatile sulphide, sulphur or pyrite at the two sites. The data suggest that previous work which did not measure non-acid-volatile products underestimated sulphate reduction rates by three-fold in the creek site, but by only one third in the pan.  相似文献   

Assessment of spatial variation in carbon utilization by benthic and pelagic invertebrates in a temperate South African estuary using stable isotope signatures     

Nicole B. Richoux  P. William Froneman 《Estuarine, Coastal and Shelf Science》2007,71(3-4):545-558

Stable isotope analyses (δ¹³C and δ¹⁵N) were used to evaluate the spatial variations in carbon flow from primary producers to consumers at two sites in the temperate and permanently open Kariega Estuary on the southeastern coast of South Africa during October 2005 and February 2006. One site was located opposite a salt marsh while the second was upstream of the marsh. Except for significantly enriched δ¹³C values of Zostera capensis and surface sediments near the salt marsh, the δ¹³C and δ¹⁵N signatures of the producers were similar between sites. The invertebrates were clustered into groups roughly corresponding to the predominant feeding modes. The suspension feeders showed δ¹³C values closest to the seston, whereas the deposit feeders, detritivores and scavengers/predators had more enriched δ¹³C values reflecting primary carbon sources that were likely a combination of seston, Spartina maritima and Z. capensis at the upstream site, with an increased influence of benthic algae and Z. capensis at the salt marsh site. The δ¹⁵N signatures of the consumers showed a stepwise continuum rather than distinct levels of fractionation, indicating highly complex trophic linkages and significant dietary overlap among the species. Consumers exhibited significantly enriched δ¹³C values at the salt marsh site, an effect that was attributed to enriched Z. capensis detritus in this region in addition to increased phytoplankton biomass in their diets compared with invertebrates living upstream. The data reinforce the concept that between-site variations in the stable isotope ratios of consumers can result not only from dietary shifts, but also from alterations in the isotope ratios of primary producers.  相似文献   

柴达木盆地第三系咸水湖相生油岩古沉积环境地球化学特征   总被引：9，自引：0，他引：9  

叶爱娟  朱扬明 《海洋与湖沼》2006,37(5):472-480

在系统分析柴达木盆地西部第三系咸水湖相生油岩样品的微量元素、有机物、粘土矿物组成的基础上,揭示了研究区生油岩的无机元素和有机质组成特征;并结合沉积环境的无机与有机地球化学指标,重建了生油岩沉积时的古沉积环境。生油岩的B、Cl-及伽玛蜡烷含量表明,沉积时的水介质条件是半咸水—咸水环境,并伴随湖盆沉积中心北迁过程各层位地层的盐度发生规律性时空]化;生油岩的Fe2 /Fe3 、S2-、Pr/Ph比值、藿烷碳数分布模式及黄铁矿含量反映其沉积时的沉积环境为强还原性;粘土矿物组合特征及含量揭示这些生油岩的沉积相带介于中心咸湖相和边缘咸湖相之间。  相似文献   

Artificial Upwelling of Deep Seawater Using the Perpetual Salt Fountain for Cultivation of Ocean Desert     

Shigenao Maruyama  Koutaro Tsubaki  Keisuke Taira  Seigo Sakai 《Journal of Oceanography》2004,60(3):563-568

Deep seawater in the ocean contains a great deal of nutrients. Stommel et al. have proposed the notion of a “perpetual salt fountain” (Stommel et al., 1956). They noted the possibility of a permanent upwelling of deep seawater with no additional external energy source. If we can cause deep seawater to upwell extensively, we can achieve an ocean farm. We have succeeded in measuring the upwelling velocity by an experiment in the Mariana Trench area using a special measurement system. A 0.3 m diameter, 280 m long soft pipe made of PVC sheet was used in the experiment. The measured data, a verification experiment, and numerical simulation results, gave an estimate of upwelling velocity of 212 m/day. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

云南程海近500年来湖泊初始生产力的演化   总被引：14，自引：1，他引：14  

吴敬禄  蒋雪中  夏威岚  潘红玺  尹宇 《海洋地质与第四纪地质》2002,22(2):95-98

程海为富营养化封闭湖泊，通过对程海CH01乳沉积物色素分析，定性恢复了近500a来程海湖泊初始生产力演化过程，结果表明，近500a来程海湖泊初始生产力总体上呈现由低到高的上升趋势，其中1700AD前后，1790AD前后是湖泊初始生产力出现变化的界限，另外，色素含量变化揭示研究时期内存在1750AD前后，1930AD前后二次明显暖波动。  相似文献   

Analysis, synthesis and modelling of high-resolution observations of salt-marsh eco-geomorphological patterns in the Venice lagoon   总被引：1，自引：0，他引：1  

Marco Marani  Enrica Belluco  Sergio Ferrari  Sonia Silvestri  Andrea D'Alpaos  Stefano Lanzoni  Alessandra Feola  Andrea Rinaldo   《Estuarine, Coastal and Shelf Science》2006,69(3-4):414

The present paper describes observations, analyses and models of salt-marsh channel network and vegetation patterns with the aim of contributing to the development of predictive models of ecological and morphological co-evolution. Existing and new observations are described, with particular emphasis on remote sensing and ancillary field surveys, which are shown to allow reliable, accurate and repeatable quantitative characterizations of landform and vegetation properties over the spatial scales of interest. The observed channel network morphological characters are then used as the basis and validation of models describing the emergence of channel network and vegetation spatial patterns. In particular, with reference to observations performed in the Venice Lagoon, the note describes: (i) new, 2-cm resolution, characterizations of channel network geometry obtained from “proximal sensing” photographic observations; (ii) the reliable quantitative maps of salt-marsh vegetation which may be retrieved from hyperspectral remote sensing data and field ancillary observations; (iii) a synthesis of recent and new analyses of the statistical properties of vegetation and landform spatial organization, that may be inferred from the maps so derived; (iv) recent and new conceptual and quantitative ecological and geomorphic models developed and validated by remote-sensing and field observations. A coherent observational and theoretical eco-morphodynamic framework is then proposed.  相似文献   

The influence of the Sabatayn Evaporites on the hydrocarbon prospectivity of the Eastern Shabwa Basin, Onshore Yemen     

T. Richard Seaborne 《Marine and Petroleum Geology》1996,13(8):963-972

The Shabwa Basin is the northeastern extension of the Marib-Al Jawf-Shabwa system of Mesozoic grabens, located onshore in the Republic of Yemen. An evaporitic sequence with an estimated maximum depositional thickness of 300 metres was deposited during the Tithonian. It is designated the Sabatayn Formation and exerts significant control on most of the play elements in the principal hydrocarbon play systems anticipated in the northeastern part of the basin. Migration of hydrocarbons from pre-salt source rocks into intra-and post-salt reservoirs is restricted by the evaporites. Localised heat flow perturbations introduced by the salt, increase the maturity of post-salt source rocks. Post and intra-salt reservoirs are structured by listric faulting on a salt detachment, salt pillowing due to post-depositional loading, by local salt dissolution and by late folding due to gravity sliding of the post-salt section on a salt detachment. Early dissolution and reprecipitation of salt is responsible for occlusion of porosity in intra-salt clastic reservoirs.  相似文献   

Colonization, succession, and nutrition of macrobenthic assemblages in a restored wetland at Tijuana Estuary, California     

Serena M. Moseman  Lisa A. Levin  Carolyn Currin  Charlotte Forder   《Estuarine, Coastal and Shelf Science》2004,60(4):755-770

Modes of colonization, the successional trajectory, and trophic recovery of a macrofaunal community were analyzed over 19 months in the Friendship marsh, a 20-acre restored wetland in Tijuana Estuary, California. Traditional techniques for quantifying macrofaunal communities were combined with emerging stable isotopic approaches for evaluation of trophic recovery, making comparisons with a nearby natural Spartina foliosa habitat. Life history-based predictions successfully identified major colonization modes, although most taxa employed a variety of tactics for colonizing the restored marsh. The presence of S. foliosa did not seem to affect macrofaunal colonization or succession at the scale of this study. However, soil organic matter content in the restored marsh was positively correlated with insect densities, and high initial salinities may have limited the success of early colonists. Total macrofaunal densities recovered to natural marsh levels after 14 months and diversity, measured as species richness and the Shannon index (H′), was comparable to the natural marsh by 19 months. Some compositional disparities between the natural and created communities persisted after 19 months, including lower percentages of surface-feeding polychaetes (Polydora spp.) and higher percentages of dipteran insects and turbellarians in the Friendship marsh. As surficial structural similarity of infaunal communities between the Friendship and natural habitat was achieved, isotopic analyses revealed a simultaneous trajectory towards recovery of trophic structure. Enriched δ¹³C signatures of benthic microalgae and infauna, observed in the restored marsh shortly after establishment compared to natural Spartina habitat, recovered after 19 months. However, the depletion in δ¹⁵N signatures of macrofauna in the Friendship marsh indicated consumption of microalgae, particularly nitrogen-fixing cyanobacteria, while macroalgae and Spartina made a larger contribution to macrofaunal diets in the natural habitat. Future successional studies must continue to develop and employ novel combinations of techniques for evaluating structural and functional recovery of disturbed and created habitats.  相似文献   

珠江河口西南风强迫下潮流场的数值模拟   总被引：1，自引：0，他引：1  

包芸  任杰 《海洋通报》2003,22(4):8-14

采用Backhaus三维斜压模型模拟了均匀西南风场对珠江口近岸海域的影响，并与无风情况作了对比；通过对珠江河口盐度场及风生环流的分析比较，结果表明，模型较为真实地再现了夏季珠江河口的水动力学特性。  相似文献   

Carbon balance in a salt marsh: Interactions of diffusive export, tidal deposition and rainfall-caused erosion   总被引：1，自引：0，他引：1  

Alice G. Chalmers  Richard G. Wiegert  Paul L. Wolf 《Estuarine, Coastal and Shelf Science》1985,21(6):757-771

Studies of the concentrations of particulate and dissolved organic carbon in the Duplin River, of the tidal exchange of POC and DOC in the marsh, of the standing stock and movement of Spartina alterniflora wrack in the Duplin, and of the removal of carbon from the surface of the marsh by rain were conducted at Sapelo Island, Georgia in order to test three hypotheses about export of carbon from the Duplin River watershed. We found that the gradients in POC and DOC concentrations are such that carbon is being transported down the Duplin River throughout the year, although in smaller quantities than previously believed. In contrast, almost all tidal exchanges within the marsh result in deposition of carbon. Most of this deposited carbon is subsequently eroded as a result of rain falling on the exposed marsh surface, and is washed back into the tidal creeks. This cycle of deposition and erosion is a possible mechanism keeping POC in the thin aerobic surface layer of the marsh, thus increasing its availability to detritivores and aerobic microbes. The standing stock of wrack is only a fraction of the S. alterniflora produced each year, and its export is a negligible term in the carbon balance equation.  相似文献