Abundance and Taxonomic Diversity of Bacteria Inhabiting the Sediment-Water Interface in a Marine Harbor Channel

Ocean Science Journal - The abundance of bacteria inhabiting the sediment-water interface and their taxonomic composition were determined with the fluorescence in situ hybridization (FISH) method...     

Incorporation,distribution and fate of saturated petroleum hydrocarbons in sediments from a controlled marine ecosystem

A simulation of a chronic input of petroleum into an estuarine environment was investigated using the facilities at the Marine Ecosystems Research Laboratory at the University of Rhode Island. An oil-water dispersion of No. 2 fuel oil was added to the system (twice weekly for 24 weeks) and the saturated hydrocarbons from this oil were measured in suspended material and sediments. After the initial chronic oil addition, trace amounts of hydrocarbons were detected in the sediments within two weeks, but substantial accumulation was not detected for approximately 135 days. The oil appeared to enter the sediment via the suspended material, with most of the saturated hydrocarbons associated with smaller size sediment particles (< 45 μm to > 0·3 μm). With time, the fuel oil saturated hydrocarbons in the sediments were mixed to a depth of 3 to 4 cm. Although only 12% of the total saturated hydrocarbons added to the system were found in the sediments, these hydrocarbons appear to be relatively stable and were still detectable in these sediments for at least six months after the last oil addition.     

A chemical investigation of the transport and fate of petroleum hydrocarbons in littoral and benthic environments: The TSESIS oil spill

The fate of saturated and aromatic hydrocarbons discharged into the coastal Baltic Sea environment from the TSESIS oil spill has been studied in the acute and postacute (one year) phases of the spill. Periodic samples of Mytilus edulis (mussels) from eight littoral zone stations and Macoma balthica from nine soft bottom stations were obtained as well as sediment trap samples and surface sediment samples. Glass capillary gas chromatography and gas chromatographic mass spectrometry were used as the analytical tools to determine saturated and aromatic hydrocarbon composition and concentrations in these samples.Sediment trap samples indicated that sizable quantities of chemically and microbially weathered oil were sedimented, and available for benthic uptake shortly after the spill. After initial uptake of sedimented oil (500 to 1000 μ/g dry weight), Macoma populations appear to have begun slow depuration through the first winter after the spill, but TSESIS oil was again introduced to the benthic stations studied during the following summer. Mytilus populations in the region were severely impacted by the oil. Initial depuration of spilled oil during the first month was rapid and nearly complete at all but the most heavily impacted stations one year after the spill. The post-spill depuration of assimilated hydrocarbons was characterised by a relative retention of alkylated dibenzothiophenes and alkylated phenanthrenes compared to their unsubstituted parent compounds and compared with the entire homologous naphthalene series.These data suggest that petroleum hydrocarbons from the TSESIS spill have become a chronic source of degraded saturated and aromatic hydrocarbons to the soft bottom benthic communities. Petroleum hydrocarbons in the benthic environment from this spill appear to reside in the difficulty sampled and mobile flucculent layer at the sediment/water interface and may affect epifaunal communities for an extended period of time.     

Effect of environmental conditions on variation in the sediment-water interface created by complex macrofaunal burrows on a tidal flat

We quantified the increase in the sediment-water interface created by the burrowing activities of the resident macrofaunal community and its variation with respect to the physical conditions of the habitat on a tidal fat. We investigated environmental factors and dimensions of macrofaunal burrows with respect to tidal height and vegetation during spring and summer at three sites. A resin-casting method was used to quantify the dimensions of all burrows at each site. The dimensions of macrofaunal burrows varied both temporally and spatially and the increase in the sediment-water interface reached a maximum of 311%, ranging from 20 to 255% under different habitat conditions. The sediment-water interface depended on the duration of exposure resulting from tidal height, increased temperatures resulting from seasonality, and marsh plant density. Burrows were deeper and more expansive at both higher tidal levels and higher temperatures in summer. Burrow dimensions were sharply reduced with the disappearance of adult macrofauna in areas where the roots of the marsh plant Suaeda japonica were dense. The significance of this study lies in quantifying the burrow dimensions of the entire macrofaunal community, rather than just a single population, and confirming their spatial and temporal variation with respect to physical conditions of the habitat. Environmental factors responsible for variation in burrow dimensions are discussed.     

Effect of environmental conditions on variation in the sediment-water interface created by complex macrofaunal burrows on a tidal flat

We quantified the increase in the sediment-water interface created by the burrowing activities of the resident macrofaunal community and its variation with respect to the physical conditions of the habitat on a tidal fat. We investigated environmental factors and dimensions of macrofaunal burrows with respect to tidal height and vegetation during spring and summer at three sites. A resin-casting method was used to quantify the dimensions of all burrows at each site. The dimensions of macrofaunal burrows varied both temporally and spatially and the increase in the sediment-water interface reached a maximum of 311%, ranging from 20 to 255% under different habitat conditions. The sediment-water interface depended on the duration of exposure resulting from tidal height, increased temperatures resulting from seasonality, and marsh plant density. Burrows were deeper and more expansive at both higher tidal levels and higher temperatures in summer. Burrow dimensions were sharply reduced with the disappearance of adult macrofauna in areas where the roots of the marsh plant Suaeda japonica were dense. The significance of this study lies in quantifying the burrow dimensions of the entire macrofaunal community, rather than just a single population, and confirming their spatial and temporal variation with respect to physical conditions of the habitat. Environmental factors responsible for variation in burrow dimensions are discussed.     

神狐海域Site4B表层沉积物中脂肪酸组成及其碳同位素分布特征

通过对神狐海域表层5个沉积物样品进行脂肪酸组成及其碳同位素分布特征测试和研究,结果表明总脂肪酸含量分布为5.14~8.99 μg/g,碳数分布范围从C₁₂到C₃₂,类型包括正构饱和脂肪酸、支链脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸和类异戊二烯酸等计48种;样品中饱和的短链脂肪酸主要来自细菌与浮游生物,而长链饱和脂肪酸来自陆源高等植物,其比例表明研究海域中海洋细菌与浮游生物输入量远远大于陆源高等植物的输入。支链脂肪酸10me16:0与单不饱和脂肪酸18:1ω9、16:1ω9主要来自硫酸盐还原菌,而单不饱和脂肪酸16:1ω7很大可能来源于硫氧化菌,比较相对含量得出神狐海域表层沉积物为还原环境。样品中检测出8种类异戊二烯酸,主要是植烷酸和17,21-ββ二升藿烷酸,及少量的姥鲛酸,推测为叶绿素a和细菌微生物的共同贡献。     

胶州湾沉积物-海水界面硅的交换速率及其影响因素探讨

采用实验室培养法在原位温度和溶氧条件下测定了胶州湾沉积物-海水界面硅的交换速率,并探讨了相关环境因子对界面交换速率的影响机制。结果表明,胶州湾沉积物-海水界面硅的交换表现为从沉积物向水体释放,其交换速率在947~4 889 μmol/（m2·d）范围内,平均速率为1 819 μmol/（m2·d）。表层沉积物中叶绿素a（Chl a）和总有机碳（TOC）是影响胶州湾沉积物-海水界面硅交换速率的主要环境因子,同时表层沉积物的含水率（φ）、生源硅（BSi）和粘土含量以及间隙水中溶解硅酸盐（DSi）对沉积物-海水界面硅的交换也有重要影响。由此可推知,胶州湾沉积物-海水界面硅的交换速率主要受生物活动和溶解-扩散双重过程调控,而表层沉积物粒度与底层水体中DSi对胶州湾硅的释放影响较小。     

Deoxygenation and remineralization above the sediment-water interface; an in situ experimental study

An in situ chamber of volume 3881 and bottom area 0·64 m² was used to determine the flux of oxygen and inorganic nutrients across an estuarine sediment-water interface over a 65-day period. Over the first 7 days, oxygen uptake was 378 mg m^?2 day^?1 and the rates of ammonium and phosphate release were 2·22 and 0·34 mg at. m^?2 day^?1, respectively. The water became anoxic in 14 days.The rates of flux in a similar chamber containing only detritus recently settled from the water column were 371 mg m^?2 day^?1 (oxygen), 1·66 mg at. m^?2 day^?1 (ammonium) and 0 12 mg at. m^?2 day^?1 (phosphate), demonstrating that detritus contributes substantially to exchange across the sediment-water interface.The evolution of the two chambers was similar over the latter part of the experimental period. A third chamber containing only water exhibited very minor changes.The role of detritus in nutrient recycling at the sediment-water interface is discussed in relation to the productivity of shallow water bodies such as the estuary in which the experiment was conducted, which itself undergoes periodic deoxygenation during prolonged stratification. The measured flux of nitrogen across the interface was found to represent approximately 31% of the mean daily phytoplankton requirement.     

黄海北部夏季无机氮赋存形态及其与反硝化速率的关系研究

用乙炔抑制法对北黄海海域沉积物-水界面反硝化速率进行了研究,并用分相浸取法对相应站位沉积物中氮的赋存形态进行了分析.结果表明,该海域界面反硝化速率在3.2.～7.5 μmol/m2·h之间,可提取无机氮的平均含量范围在0.7 2～80.36 μg/g之间.对两者之间的关系研究表明,该海域反硝化速率与沉积物中离子交换态(IEF)硝酸盐氮和可提取无机总氮之间存在较好的相关性,相关系数分别为0.947和0.88 6(P＜0.01);与碳酸盐结合态(CF)和铁锰氧化物态(IMOF)的硝酸盐氮及氨氮之间相关性不明显.     

Transport of no. 2 fuel oil between water column,surface microlayer and atmosphere in controlled ecosystems

No. 2 fuel oil hydrocarbons put into the bulk water columns of controlled estuarine ecosystems were found to accumulate in the surface microlayer at the air-water interface. The alkane hydrocarbons were disproportionately enriched in the microlayer compared with the aromatic hydrocarbons. A comparison of hydrocarbon boiling point distributions between bulk water, microlayer and air samples indicated that the oil hydrocarbons underwent extensive weathering by evaporation upon reaching the air-water interface. No evidence was found of increased biodegradation in the microlayer compared with that in the underlying water. A fraction of the high molecular weight alkanes, the least water soluble and least volatile constituents of the oil, appeared to be coated out from the microlayer onto the inner walls of the ecosystems.     

Composition and bacterial utilization of free amino acids in tropical mangrove sediments

The composition and bacterial utilization of dissolved free amino acids (DFAA) in tropical mangrove sediments was examined. Amino acid concentrations (300–900 ng total DFAA ml⁻¹) and composition were similar to that of other organic-rich, anaerobic sediments with lowest and highest concentrations in the low and mid intertidal zones, respectively. The non-protein amino acid, β-glutamic acid, rarely reported in previous studies, was found as a major component of the interstitial DFAA pool. Intracellular amino acids from some cultured strains of sulphate-reducing bacteria (e.g. Desulfobacter app) showed the presence of β-glutamic acid as a major cellular constituent suggesting that these bacteria may be a source of this amino acid in mangrove pore waters. In high intertidal sediments, bacterial growth rates (μ) correlated significantly with total DFAA concentrations with depth.Amino acid concentrations and composition differed significantly between sediments and overlying tidal waters. Flux chamber experiments showed negligible amino acid flux out of the sediments in untreated chambers, but rates of amino acid flux ranged from 27 to 69 mgN m⁻² day⁻¹ (= 81–207 mg C.m⁻² day⁻¹) in chambers where poisons were applied to the sediment surface. Such fluxes could account for between 9–38% and 5–19% of the nitrogen and carbon required to support the levels of bacterial productivity measured in surface (0–1 cm) sediments. These experiments suggest that bacterial populations in surface sediments are capable of utilizing all of the amino acid flux to the sediment-water interface in tropical mangroves.     

The sediment-water interface increment due to the complex burrows of macrofauna in a tidal flat

The architecture of macrofaunal burrows and the total area of the sediment-water interface created by biogenic structure were investigated in the Donggeomdo tidal flat on the west coast of Korea. Resin casting methods were applied to recover burrows of four dominant species, Macrophthalmus japonicus, Cleistostoma dilatatum, Perinereis aibuhitensis, and Periserrula leucophryna, and whole burrows within the casting area at three sites in different tidal levels.P. leucophryna excavated the largest burrow in terms of a surface area among them. In the case of whole burrow casting, the space occupied by the biogenic structure was extended into deeper and expanded more greatly at the higher tidal level. In the uppermost flat, the burrow wall surface area within sediment was more extensive than the sediment surface area. Increased oxygen supply through the extended interface could enhance the degradation rates of organic carbon and also change the pathways of degradation. Quantifying the relationship between the extended interface and mineralization rate and pathway requires more extensive study.     

Processes affecting the behavior of dissolved aluminum in estuarine waters

Although it is well-known that reactions occur within estuaries to alter the flux of dissolved aluminum from rivers into the oceans, the nature and relative importance of these reactions are not well defined. In this study we show that sediment-water interactions can have a significant influence on dissolved Al distributions in estuaries. Undisturbed sediments will act as a sink for dissolved Al because of diffusion across the sediment-water interface and reaction of Al within the sediment. Resuspension of sediments will cause a release of dissolved Al into relatively Si-depleted estuarine waters.Flocculation of colloidal material may cause a net consumption of dissolved Al in estuaries. Our results indicate, however, that this process may not, in many cases, be the primary cause for curvature in Al-Cl^? profiles. An alternative model, whereby Al is displaced from organic matter complexes and adsorption sites in the estuarine zone and reacts with Si and cations in solution, is consistent with the data presented in this study as well as many other studies. In this case, the extent of net Al removal in estuaries will be determined by both the amount and nature of the dissolved organic matter present.     

Annual Variation of Benthic Nutrient Fluxes in Shallow Coastal Waters (Gulf of Trieste, Northern Adriatic Sea)

Abstract. Benthic fluxes of dissolved N. Si and P nutrients, alkalinity, dissolved inorganic C (DIC), and O₂ from sediments in the Gulf of Trieste (northern Adriatic, Italy) were measured monthly for 16 months, using laboratory incubated flux chambers at in siru temperatures in the dark. The annual average fluxes were: 02 = -19.3 ± 8.2, DIC = 13.7 ± 9.6, NO3 = -0.04 ± 0.16, NH4 = 0.3 ± 0.4. PO₄= 4.001 ± 0.01, Si = 0.9 ± 0.1 mmol m-² d^-1, with strong temporal fluctuations. The highest effluxes of all nutrients and DIC were observed in the summer. Small effluxes of DIC and NH4 and influxes of Si and PO4 were observed in late winter. Only NH₄ (ca. 50%) and Si (ca. 70%) fluxes were significantly correlated with temperature. This correlation suggests that the rate of downward input and the quality of sedimented organic matter (autochthonous and allochthonous) were superimposed on the temperature fluctuations. High DIC, NH₄ and Si effluxes observed in May 1993 during low temperature were due to the degradation of sedimentary organic matter produced by an early spring bloom of benthic microalgae which occurred about 6 weeks earlies while the autumn phytoplankton bloom was simultaneously reflected in enhanced benthic fluxes due to higher temperature. The role of benthic biological advection in this transport across the sediment-water interface, evaluated by comparison between measured benthic and calculated diffusive fluxes from nutrient pore water concentrations, was of minor importance. This is probably due to low infaunal activity throughout the year it was localized mostly in the narrow surficial layer. The annual average diffusive fluxes of NH4 and PO4 were higher than those measured, probably due to the presence of nitrificationdenitrifi-cation processes and redox-dependent chemical reactions at the oxic sediment-water interface, respectively. Only during bottom-water hypoxia in September 1993 did strong PO₄ effluxes prevail. Calculations based on the Redfield stoichiometry of oxic decomposition of organic N to NH4 and NO3, and differences between diffusive and measured NH₄ fluxes showed that denitrifkation averaged 0.8 mmol m^-2 d^-1. Significant correlations between NH₄ and PO₄ DIC and Si, and NH4 and Si fluxes suggested their parallel regeneration and utilization at the sediment-water interface. The nutrient fluxes observed were not significantly linked to O₂ consumption, suggesting also that anaerobic oxidation processes were important at the sediment-water interface in the gulf. The N, P and Si nutriqnts released from sediment pore waters are probably utilized in benthic microalgal and bottorn-hater primary production. This indicates that pelagic and benthic communities in the central part of the Gulf of Trieste function relatively independently of each other.     

Carbon isotopic composition and lattice-bound carbonate of Peru-Chile margin phosphorites

New light-stable carbonate-carbon isotope and lattice-bound CO₂ data from Quaternary Peru-Chile margin phosphatic nodules, crusts and pelletal grains, and from associated dolomicritic concretions, are presented, which provide constraints on the timing and mechanisms of growth of these phases in organic carbon-rich sediments. Comparison of δ¹³C values from carbonate fluorapatite (CFA) nodules and pelletal grains (−4.8 to 0.0‰ and −2.9 to +1.0‰ PDB, respectively) with pore-water total dissolved δ¹³C values from these sediments suggests early authigenic CFA precipitation from pore waters within a few centimeters of the sediment-water interface in association with suboxic to perhaps anoxic microbial degradation of organic matter. In contrast, the dolomicritic cores of nodules recovered from about 12°S display both strongly negative to positive δ¹³C values (−10.8 to +6.1‰) characteristic of formation deeper in the sediments in association with methanogenic and perhaps sulfate reduction microbial processes.

The amount of structural carbonate in CFA suggests that carbonate substitution generally increases as δ¹³C in CFA decreases, a probable consequence of increasing carbonate and accompanying charge-balancing substitutions in the CFA lattice in response to increasing pore-water carbonate ion concentrations with depth below the sediment-water interface. In one buried upward-growing nodule, decreasing CFA δ¹³C and increasing structural CO₂ also correspond to decreasing CFA growth rates. These data suggest that in addition to other constraints such as pore-water phosphorus and fluoride availability, the lower limit of CFA precipitation in suboxic to anoxic sediments may be controlled by lattice poisoning due to excessive dissolved carbonate ion concentrations. In organic-rich Peru-Chile margin sediments this depth threshold appears to be at approximately 5–10 cm below the sediment-water interface where maximum CFA CO₂ contents of about 6 Wt.% occur; in less organic-rich settings, greater depths of precipitation of CFA may be anticipated. Below this relatively shallow depth of CFA precipitation on the Peru shelf, high pore-water alkalinity and associated elevated total dissolved carbon and carbonate ion concentration apparently favor the precipitation of authigenic carbonates.     

Effects of commercial dragging on sedimentary organic matter

The effect of commercial dragging on sedimentary organic matter was examined in two field experiments using different types of gear. A heavy scallop dredge caused two types of organic matter translocation—some of the surficial organic matter was exported from the drag site and the remaining material was mixed into subsurface sediments. Phospholipid analysis indicated decreases in various classes of microbial, with relative increases in the contribution of anaerobic bacteria to the microbial community. An other trawl that largely remained above the sediment-water interface caused little change in organic matter profiles, although ⁷Be profiles suggest an export of the surficial horizon. Sediment mixing by some types of gear will likely result in burial of labile organic matter and hence may shift sediment metabolism toward microbial and anaerobic food chains.     

Nitrogen and Phosphorus Diffusive Fluxes Across the Sediment-Water Interface in Estuarine and Coastal Tidal Flats

Nitrogen and phosphorus contents are analyzed in the overlying waters and pore waters taken from the Changjiang Estuary and Shanghai coastal tidal flats in this study. In addition, the diffusion fluxes of nitrogen and phosphorus across the sediment-water interface in tidal flats are estimated according to the nutrient concentration gradients at the interface. It has been indicated that the concentrations of ammonium, nitrite, nitrate and dissolved phosphorus in overlying waters range from 0.0082～2.56, 0.03～0.58, 0.69～5.38 and 0.035～0.53 mg/L, respectively, while 0.0025 ～ 1.35 mg/L for NH4+-N, 0. 0055 ～ 0.20mg/L for NO2--N, 0.61～1.14 mg/L for NO3--N and 0.11～0.53mg/L for DP insurface pore waters.The findings have revealed that ammonium, nitrite, nitrate and dissolved phosphorus diffusion fluxes across the sediment-water interface are between -0.024～0.99, -0.39～ -0.0019, -3.09～the source of phosphorus and an important sink for nitrogen in the waters.     

Observations of the Sediment-Water Interface: Marine and Fresh Water Environments

The sediment at the interface immediately beneath the water column is distinct from deeper-lying sediments in its properties and, at least quantitatively, in the processes driving diagenesis. Progress in understanding the sediment-water interface can be based on consideration of fundamentals of biogeochemical particle / fluid interactions and on application of certain biological techniques especially suited to this challenging portion of the sediment column. This article reports results achieved by combining theoretical fundamentals and specialized experimental techniques in the study of the interface from selected depositional environments. For fine-grained and sandy deposits from fresh-water to coastal marine environments, the interface is characterized by exaggerated microrelief, great porosity, and significant biological alteration. Additional application of this research approach is poised to further our understanding of engineering, and acoustic and xenochemical responses of sedimentary materials, with special emphasis on the influence of the bio-organic phase of the interface upon its fabric and physical properties.     

Observations of the Sediment-Water Interface: Marine and Fresh Water Environments

The sediment at the interface immediately beneath the water column is distinct from deeper-lying sediments in its properties and, at least quantitatively, in the processes driving diagenesis. Progress in understanding the sediment-water interface can be based on consideration of fundamentals of biogeochemical particle / fluid interactions and on application of certain biological techniques especially suited to this challenging portion of the sediment column. This article reports results achieved by combining theoretical fundamentals and specialized experimental techniques in the study of the interface from selected depositional environments. For fine-grained and sandy deposits from fresh-water to coastal marine environments, the interface is characterized by exaggerated microrelief, great porosity, and significant biological alteration. Additional application of this research approach is poised to further our understanding of engineering, and acoustic and xenochemical responses of sedimentary materials, with special emphasis on the influence of the bio-organic phase of the interface upon its fabric and physical properties.