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PubMed1996

Bioavailability and effect of pirimicarb on Daphnia magna in a laboratory freshwater/sediment system.

In tests with newborn and one-week-old Daphnia magna, 48-h EC50 values of 21-24 microg/L and 16 microg/L pirimicarb, respectively, were found. Older animals thus were as sensitive to pirimicarb as newborn animals. In an experiment with sediment included in the test system, all mother animals survived for 72 h at 20 microg/L, and the number of offspring was not reduced relatively to the control. Addition of sediment thus reduced the toxicity of pirimicarb toward Daphnia magna. Pirimicarb was accumulated 12-16 times (5-7% of total) in the sediment, but the water concentrations of pirimicarb were not reduced significantly during the experiment, due to the small amount of sediment used. Accumulation in the sediment was found independent of the water concentration used. This was also the case with bioaccumulation in Daphnia magna, where a bioaccumulation factor of 31-37 was found on a dry weight basis. In water without sediment a BCF of 50 was found. Addition of sediment also reduced the accumulation of pirimicarb in the daphnids. The reduced bioavailability of pirimicarb may derive from humic acid and related compounds released from the sediment.

Animals↗
PubMed2005

Pretreatment procedures for characterization of arsenic and selenium species in complex samples utilizing coupled techniques with mass spectrometric detection.

Research interest in analyzing arsenic and selenium is dictated by their species-dependent behavior in the environment and in living organisms. Different analytical methodologies for known species in relatively simple chemical systems are well established, yet the analysis of complex samples is still a challenge. Owing to the complex matrix and low concentrations of target species that may be chemically labile, suitable pretreatment of the sample becomes a critical step in any speciation procedure. In this paper, the pretreatment procedures used for arsenic and selenium speciation are reviewed with the emphasis on the link between the analytical protocol applied and the biologically-significant information provided by the results obtained. In the first approach, the aim of pretreatment is to convert the original sample into a form that can be analyzed by a coupled (hyphenated) technique, preventing possible losses and/or species interconversion. Common techniques include different leaching and extraction modes, enzymatic hydrolysis, species volatilization, and so on, with or without species preconcentration. On the other hand, if the speciation analysis is performed for elucidation of elemental pathways and specific functions in a living system, more conscious pretreatment and/or fractionation is needed. The macroscopic separation of organs and tissues, isolation of certain types of cells, cell disruption and separation of sub-cellular fractions, as well as isolation of a specific biomolecules become important. Furthermore, to understand molecular mechanisms, the identification of intermediate-often highly instable--metabolites is necessary. Real life applications are reviewed in this work for aquatic samples, soils and sediments, plants, yeast, and urine.

Arsenic↗
PubMed2000

Relative acute toxicity of acid mine drainage water column and sediments to Daphnia magna in the Puckett's Creek Watershed, Virginia, USA.

Acid mine drainage (AMD) is produced when pyrite (FeS(2)) is oxidized on exposure to oxygen and water to form ferric hydroxides and sulfuric acid. If produced in sufficient quantity, iron precipitate, heavy metals (depending on soil mineralogy), and sulfuric acid may contaminate surface and ground water. A previous study of an AMD impacted watershed (Puckett's Creek, Powell River drainage, southwestern Virginia, USA) conducted by these researchers indicated that both water column and sediment toxicity were significantly correlated with benthic macroinvertebrate community impacts. Sites that had toxic water or sediment samples had significantly reduced macroinvertebrate taxon richness. The present study was designed to investigate the relative acute toxicity of acid mine drainage (AMD) water column and sediments to a single test organism (Daphnia magna) and to determine which abiotic factors were the best indicators of toxicity in this system. Nine sampling stations were selected based on proximity to major AMD inputs in the watershed. In 48-h exposures, sediment samples from three stations were acutely toxic to D. magna, causing 64-100% mortality, whereas water samples from five stations caused 100% mortality of test organisms. Forty-eight-hour LC50 values ranged from 35 to 63% for sediment samples and 27 to 69% for water column samples. Sediment iron concentration and several water chemistry parameters were the best predictors of sediment toxicity, and water column pH was the best predictor of water toxicity. Based on these correlations and on the fact that toxic sediments had high percent water content, water chemistry appears to be a more important adverse influence in this system than sediment chemistry.

Animals↗
PubMed2001

Specific 16S rDNA sequences associated with naphthalene degradation under sulfate-reducing conditions in harbor sediments.

Previous studies have demonstrated that naphthalene and other polycyclic aromatic hydrocarbons (PAHs) can be anaerobically oxidized with the reduction of sulfate in PAH-contaminated marine harbor sediments, including those in San Diego Bay. In order to learn more about the microorganisms that might be involved in anaerobic naphthalene degradation, the microorganisms associated with naphthalene degradation in San Diego Bay sediments were evaluated. A dilution-to-extinction enrichment culture strategy, designed to recover the most numerous culturable naphthalene-degrading sulfate reducers, resulted in the enrichment of microorganisms with 16S rDNA sequences in the d-Proteobacteria, which were closely related to a previously described pure culture of a naphthalene-degrading sulfate reducer, NaphS2, isolated from sediments in Germany. A more traditional enrichment culture approach, expected to enrich for the fastest-growing naphthalene-degrading sulfate reducers, yielded 16S rDNA sequences closely related to those found in the dilution-to-extinction enrichments and NaphS2. Analysis of 16S rDNA sequences in sediments from two sites in San Diego Bay that had been adapted for rapid naphthalene degradation by continual amendment with low levels of naphthalene suggested that the microbial community composition in the amended sediments differed from that present in the unamended sediments from the same sites. Most significantly, 6-8% of the sequences recovered from 100 clones of each of the naphthalene-amended sediments were closely related to the 16S rDNA sequences in the enrichment cultures as well as the sequence of the pure culture, NaphS2. No sequences in this NaphS2 phylotype were recovered from the sediments that were not continually exposed to naphthalene. A PCR primer, which was designed based on these phylotype sequences, was used to amplify additional 16S rDNA sequences belonging to the NaphS2 phylotype from PAH-degrading sediments from Island End River (Boston), MA, and Liepaja Harbor, Latvia. Closely related sequences were also recovered from highly contaminated sediment from Tampa Bay, FL. These results suggest that microorganisms closely related to NaphS2 might be involved in naphthalene degradation in harbor sediments. This finding contrasts with the frequent observation that the environmentally relevant microorganisms cannot be readily recovered in pure culture and suggests that further study of the physiology of NaphS2 may provide insights into factors controlling the rate and extent of naphthalene degradation in marine harbor sediments.

Biodegradation, Environmental↗
PubMed2006

Microbial communities on glacier surfaces in Svalbard: impact of physical and chemical properties on abundance and structure of cyanobacteria and algae.

Microbial communities occurring in three types of supraglacial habitats--cryoconite holes, medial moraines, and supraglacial kames--at several glaciers in the Arctic archipelago of Svalbard were investigated. Abundance, biovolume, and community structure were evaluated by using epifluorescence microscopy and culturing methods. Particular emphasis was laid on distinctions in the chemical and physical properties of the supraglacial habitats and their relation to the microbial communities, and quantitative multivariate analyses were used to assess potential relationships. Varying pH (4.8 in cryoconite; 8.5 in a moraine) and texture (the proportion of coarse fraction 2% of dry weight in cryoconite; 99% dw in a kame) were found, and rather low concentrations of organic matter (0.3% of dry weight in a kame; 22% dw in cryoconite) and nutrients (nitrogen up to 0.4% dw, phosphorus up to 0.8% dw) were determined in the samples. In cryoconite sediment, the highest numbers of bacteria, cyanobacteria, and algae were found, whereas relatively low microbial abundances were recorded in moraines and kames. Cyanobacterial cells were significantly more abundant than microalgal ones in cryoconite and supraglacial kames. Different species of the cyanobacterial genus Leptolyngbya were by far the most represented in all samples, and cyanobacteria of the genera Phormidium and Nostoc prevailed in cultures isolated from cryoconite samples. These species are considered opportunistic organisms with wide ecological valency and strong colonizing potential rather than glacial specialists. Statistical analyses suggest that fine sediment with higher water content is the most suitable condition for bacteria, cyanobacteria, and algae. Also, a positive impact of lower pH on microbial growth was found. The fate of a microbial cell deposited on the glacier surface seems therefore predetermined by the physical and chemical factors such as texture of sediment and water content rather than spatial factors or the origin of sediment.

Cyanobacteria↗
PubMed2005

Phylogenetic analysis of Archaea in the deep-sea sediments of west Pacific Warm Pool.

Archaea are known to play important roles in carbon cycling in marine sediments. The main compositions of archaeal community in five deep-sea sediment samples collected from west Pacific Warm Pool area (WP-0, WP-1, WP-2, WP-3, WP-4), and in five sediment layers (1 cm-, 3 cm-, 6 cm-, 10 cm-, 12 cm- layer) of the 12 cm sediment core of WP-0 were checked and compared by denaturing gradient gel electrophoresis and 16 S rRNA gene sequencing. It was revealed that all the deep-sea sediment samples checked contained members of non-thermophilic marine group I crenarchaeota as the predominant archaeal group. To further detect groups of archaea possibly relating with C1 metabolism, PCR amplification was carried out using primers targeting methane-oxidizing archaea. Although no methane-oxidizing archaea was detected, a group of novel archaea (named as WPA) was instead identified from all these five WP samples by clone analysis. They could be placed in the euryarchaeota kingdom, separated into two distinct groups, the main group was peripherally related with methanogens, the other group related with Thermoplasma. The vertical distributions of WPA, archaea and bacteria along the WP-0 sediment column were determined by quantitative-PCR. It was found that bacteria dominated at all depths, the numbers of bacteria were 10-10(4) times more than those of archaea. The proportion of archaea versus bacteria had a depth related increasing tendency, it was lowest at the first layer (0.01%), reached highest at the 12 cm- layer (10%). WPA only constituted a small proportion of the archaeal community (0.05% to 5%) of west Pacific Warm Pool sediment.

Archaea↗
PubMed2005

Evaluation of different bioremediation protocols to enhance decomposition of organic polymers in harbour sediments.

The response of the microbial community (in term of abundance and enzymatic activity) was investigated to test the effect of different bioremediation protocols to naturally enhance decomposition of organic polymers in harbour sediments (Genoa Harbour, Italy, N-W Mediterranean). Bioremediation techniques tested were bioaugmentation (5 different microorganisms' inocula), biostimulation (air supply), and natural attenuation. The coupling bioaugmentation/biostimulation was also tested. After 60 days, following the bioaugmentation protocol, bacterial densities correlated to the quantities of inocula amended to the boxes, suggesting that allochthonous community was able to survive and multiply. However, while bioaugmentation alone seems not to be able to carry out significative degradation, its coupling with air insufflations produced the best response: here bacterial densities increased, especially in the water (from 2.3 x 10(7) to 3.50 x 10(8) cells ml(-1)), average cell size and enzymatic activities increased, and sedimentary organic matter was significantly depleted (PRT 5-folds reduction, CHO 1.5-folds reduction). The strong coupling observed between the sediment and water compartments together with the greatest microbial response observed in this latter suggest that the sediment-water interface may constitute a key compartment for the occurring of biodegradation processes in organic-rich sediments.

Bacteria↗
PubMed2006

The contamination levels of organochlorine pesticides in water and sediment samples in Uluabat Lake, Turkey.

The Uluabat Lake is a reservoir of 125 km2 surface area, in the boundaries of Bursa province, Turkey. The results showed that Uluabat Lake was still contaminated by organochlorine pesticides and their residues despite the existence of bans over a long time. Considerable amounts of organochlorine pesticides (HCB, p.p'-DDT, p.p'-DDE, alpha-, beta- and gamma-BHC, Aldrin, Heptachlor epoxide, Endrin, Endosulfan I and II) were detected in water and sediment samples during one-year study in this lake. Samples of water and sediment were collected in different regions, (6 sampling point) of the lake between February 2002 and November 2002. The mean levels of organochlorine pesticides in water and sediments were determined. According to results, it was found that various environs in Uluabat Lake were contaminated by 11 different organochlorine pesticides. Residue analyses showed that higher organochlorine pesticides and their residues were generally more accumulated in the sediment samples.

Agriculture↗
PubMed2004

Bioaccumulation of PAHs from creosote-contaminated sediment in a laboratory-exposed freshwater oligochaete, Lumbriculus variegatus.

The oligochaete, Lumbriculus variegatus, was used for a bioaccumulation assay in the creosote-contaminated sediment of Lake Jämsänvesi in a 28-day experiment. The PAH concentrations of the whole body tissue of worms, sediments and water samples were determinated by GC-MS. Chemical analyses showed that benzo(k)fluoranthene, anthracene and fluorene were the main PAH compounds present in the tissue of oligochaetes, just as in the sediment. The biota-sediment accumulation factors (BSAFs) of the individual PAHs varied from 1.2 to 5.7. It is concluded that oligochaetes have a marked ability to accumulate and retain PAHs from creosote-contaminated sediment.

Animals↗
PubMed2006

TNT leakage through sediment to water and toxicity to Nitocra spinipes.

The fate and effects of 2,4,6-trinitrotoluene (TNT) at marine ammunition dumping sites are essentially unknown. The objective of this study was to examine the release from solid TNT to seawater when covered by sediment of two different types (sandy and fine-grained) and thickness (0, 1, 2, and 4 cm), under different temperatures (5, 10, and 20 degrees C), and light conditions (ambient daylight and darkness) in the laboratory. The water column was analysed for TNT and some of its common transformation products, and toxicity to the copepod Nitocra spinipes after 1, 2, 4, 8, 19, and 32 weeks. Leakage of TNT to seawater and the toxicity to N. spinipes was significantly reduced by sediment burial, especially in fine-grained sediment. Hence, this study suggests that adverse effects of TNT in dumped ammunition on aquatic organisms should be delayed/reduced at low temperature and when TNT is covered sediment, especially with fine-grained sediment.

Animals↗
PubMed2005

Benthic impacts of fish farming: meta-analysis of community and geochemical data.

A number of 41 papers dealing with the benthic effects of fish farming were reviewed and the values of the variables studied were extracted to be used in a meta-analysis of effects. The papers used covered a wide range of farmed species, geographic regions, management practices and specific site characteristics (e.g., depth, exposure, and sediment type). Therefore, the total data-set may not be considered as biased towards a particular set of conditions as is often the case with data collected in a single study. More than 120 biological and geochemical variables were monitored, occasionally using different sampling and analytical protocols for the same variables. The rank correlation analysis between all possible pairs of variables in the data set showed a large number of significant positive or negative correlations, reflecting the response of these variables to benthic organic enrichment. The use of stepwise regression showed that most biological and geochemical variables are determined by a combination of distance from the farm with bottom depth and/or latitude. Results of stepwise regression, repeated separately for each type of sediment, showed that although the general pattern was similar among different types of sediments, the coefficients varied considerably indicating changes of the distance affected by settling particulate organic material for different sediment types. The overall conclusion is that the complicated interactions between variables and the lack of data, such as current speed, induce difficulties in setting common or uniform environmental quality standards for benthic effects of fish farming and these should take into account the existing considerable differences between geographic regions, depth zones and sediment types.

Animals↗
PubMed2006

The observation and quantification of oil migration and binding in sediments using T2 magnetic resonance imaging.

Magnetic resonance imaging (MRI) makes use of the interactions between atomic nuclei and an external, strong, magnetic field to image the distribution of these nuclei through a substance. In this study, proton MRI has been used to indicate the presence of oil in sediment. Using a multiecho spin-echo acquisition sequence, images of relative oil density, and hence concentration, and of the magnetic resonance relaxation rate, T2, were produced. T2, which is greatly influenced by molecular motion, was equated to binding between the oil and the sediment, thus, providing an almost real-time "description" of all aspects of the oil-sediment interaction including motion of the oil. The interactions among three sediments from the Tay Estuary (East Coast of Scotland) and three crude oils (Fulmar, Forties and Venezuelan) are discussed. Observation of changes in images of oil density and changes in T2, using spread sheets, allow both rates of diffusion of the oil into the sediment and changes in the binding of the oil to the sediment to be calculated. Both the Forties and Fulmar oils move more rapidly than the Venezuelan oil in all of the sediments examined, while the strength of binding is sediment dependent. Thus, the ability of MRI to distinguish between the rates of flow of the oils into the sediment and the strengths of interaction between the various sediments and oils is demonstrated.

Fuel Oils↗
PubMed2002

Impact of offsite sediment transport and toxicity on remediation of a contaminated estuarine bay.

Sediment of Ostrich Bay, an arm of Dyes Inlet on Puget Sound, was historically contaminated with ordnance compounds from an onshore US Navy facility. An initial recommendation for a sediment cover to mitigate benthic risks was followed by studies of sediment transport and deposition to determine whether contaminated sediment from Dyes Inlet or other offsite sources in Puget Sound may contribute to Ostrich Bay impacts. A Sediment Trend Analysis (STA) identified net sediment transport pathways throughout the bay and inlet by examining changes in grain size distributions in multiple adjacent samples. Results indicated that fine-grained sedimentary material transports into and deposits throughout the Dyes Inlet system, with no erosion or transport out of Ostrich Bay. Echinoderm larvae mortality bioassay results were elevated in fine-grained sediments of both Ostrich Bay and Dyes Inlet. Ordnance compounds were undetected, and although sediment mercury concentrations were elevated at 0.48-1.4 mg/kg in both waterbodies, the relationship with toxicity was weak. Results of the studies and sedimentation modeling indicate that impacted sedimentary material deposits throughout the Dyes Inlet/Ostrich Bay system from unknown sources and will prevent natural recovery of Ostrich Bay as well as negate long-term effectiveness of active remedial measures. Stakeholders have recognized that remediation of the bay can be achieved only after the toxicity of depositing sediment decreases.

Animals↗
PubMed2002

Burial, exportation and degradation of acyclic petroleum hydrocarbons following a simulated oil spill in bioturbated Mediterranean coastal sediments.

A field study was conducted in a French Mediterranean littoral (Gulf of Fos) in order to determine the role of bioturbation processes during the bioremediation of oil-contaminated sediments. Inert particulate tracers (luminophores) and Arabian light crude oil were deposited at the surface of sediment cores incubated in situ for 2, 6 and 12 months. After incubation, luminophores and hydrocarbons presented roughly similar depth distributions in the sediment, showing a continuous burial of material until 55 mm depth. Short-chain (< or = n-C25) n-alkanes were totally removed from the sedimentary column after 6 months, whereas approximately 20% of heavier n-alkanes (e.g. n-C30) and of isoprenoid hydrocarbons (pristane (Pr) and phytane (Ph)) remained at the end of the experiment. The determination of the degradation constant and the turn-over rate of individual hydrocarbon indicated that C17-25 n-alkanes were degraded two to three times faster than longer homologues and than pristane and phytane. Using the 17alpha,21beta-C30-hopane as an internal inert reference, we could demonstrate that, after 12 months of in situ incubation, 55% of the losses of the n-alkanes < or = C25 and 35% of the losses of the heavier n-alkanes and of Pr and Ph were due to biodegradation processes. These results demonstrate that the activity of benthic organisms can have a significant influence on the qualitative and quantitative fate of acyclic hydrocarbons following a petroleum contamination in marine coastal sediments.

Animals↗
PubMed2003

Horizontal and vertical variabilities of mercury concentration and speciation in sediments of the Gdansk Basin, Southern Baltic Sea.

The mercury compounds introduced to the environment because of anthropogenic activity are accumulated, mainly, in marine sediments. Both distribution of mercury in the Baltic Sea and factors affecting it are remain largely unknown. Due to its complex chemistry and variable conditions in the Baltic Sea bottom sediments, mercury may be reemitted to the overlaying water, and thus to the environment. The aim of this study was twofold. Total mercury contents were measured in sediments of the Gdansk Basin along a Vistula mouth (main source)--Gdansk Deep (deposition area) transect in order to assess spatial distribution of the element. Soft and sandy bottom sediment cores were collected and cut into slices. The mercury measurements consisted of acid digestion followed by CV-AAS determination. A five-step sequential extraction procedure involving measurements of mercury species water soluble, bound to humic substances and insoluble, was employed in order to investigate mercury speciation. On the basis of speciation results stability and remobilisation potential was assessed. The second aim was demonstrating that mercury gradients in vertical profiles of the investigated sediment cores exist. Total mercury contents varied in range from 28 ng/g x dw to 844 ng/g. Mercury associated with organic matter and sulphides, (respectively 39% and 49%) were the dominant species of the element. The results indicated that the river run-off is a source of mercury in the area. Vertical gradients of both total content and speciation of mercury in the soft sediments were attributed to both remobilisation from sediments, and decreasing trend in the anthropogenic load of the element deposited to sediments.

Baltic States↗
PubMed2001

Controls on the nutrient content of suspended sediment transported by British rivers.

Recent studies of nutrient fluxes from river basins have emphasised the importance of sediment-associated transport. In order to develop an improved understanding of sediment-associated nutrient transport in UK rivers and of contrasts between individual rivers, attention has been directed to spatial and temporal variations in the nutrient (N and P) content of suspended sediment transported by four rivers, which embrace a representative range of British conditions. Bulk samples of suspended sediment were collected during storm events and these were analysed for both total N and P content and for individual fractions of these nutrients. Significant temporal and spatial variability in these various measures of the nutrient content of suspended sediment has been documented. Spatial variability has been linked to catchment characteristics, which in turn influence sediment sources. Patterns of temporal variability, which are reasonably consistent among the different rivers, have been related both to variations in other sediment properties and to hydrometeorological conditions.

Geologic Sediments↗
PubMed2003

Modelling intertidal sediment transport for nutrient change and climate change scenarios.

A model of intertidal sediment transport, including effects of bioturbation and biostabilisation, was applied to two transects on the east coast of England: Leverton (within the Wash) and Skeffling (in the Humber Estuary). The physical and biological parameters were chosen to represent four 1-year scenarios: a baseline year (1995), the same year but with estuarine nitrate inputs reduced by 50% and by 16%, and a year with climate change effects estimated for 2050. The changes in nitrate supply can potentially change microphytobenthos numbers within the surface sediment, which will then affect erodibility. The model results show a range of behaviour determined by bathymetry, external forcing and biotic state. When intertidal sediment transport is dominated by external sediment supply, the model produces highest deposition at the most offshore point, and there is greatest deposition in the winter and spring, when offshore sediment concentrations are highest. When intertidal processes dominate intertidal sediment transport, there is a peak of deposition at the high-shore level and erosion at mid-tide levels. The greatest deposition now occurs in winter and summer, when low chlorophyll levels mean that the sediment is most erodible. The Skeffling transect was dominated by intertidal processes for the baseline scenario and with a 16% reduction in nitrate. Under the climate change (warm winter) scenario, the Skeffling transect was dominated by external sediment supply. The scenario with 50% reduction in nitrate gave intermediate behaviour at Skeffling (intertidally driven during the winter and summer, and governed by offshore sediment supply during spring and autumn). The Leverton transect was dominated by offshore sediment supply for all the scenarios.

Chlorophyll↗
PubMed2000

Effects of sediment geochemical properties on the toxicity of copper-spiked sediments to the marine amphipod Gammarus locusta.

The contribution of some sediment features, namely acid-volatile sulfide (AVS) and total organic carbon (TOC) in order to explain the toxicity of copper-spiked sediments was investigated. A 10-day assay with the marine amphipod Gammarus locusta was performed with three selected sediment types that consisted of different proportions of fine fractions (FF) and TOC (0.5% FF/1% TOC; 25% FF/2% TOC; and 75% FF/4% TOC). Copper toxic effects were observed for 0.5% FF/25% FF sediments when simultaneously extracted copper (SEM(Cu)) minus acid volatile sulfide (SEM(Cu) - AVS) were 0.3 and 3.4 micromol/g, respectively. However, no significant mortality was observed for 75% FF sediment even when the sulfide binding capacity was exceeded (1.1 micromol/g < or = SEM(Cu) - AVS < or = 8.9 micromol/g). These results indicate that mortality could not be described solely as a function of the SEM(Cu) - AVS, suggesting the presence of other binding phases in addition to AVS. Results of the normalized LC50 values to total organic carbon indicated that this component probably also interferes in the amphipod survival, although not completely. The estimated LC50 values were close (2 mg Cu/g C and 8 mg Cu/g C, respectively for 0% FF and 25% FF sediment) although there was still a fourfold difference between them. Considering that none of these sediment features by itself could fully explain copper toxicity, an attempt was made to describe G. locusta mortality as a function of simultaneous SEM(Cu) - AVS and copper concentrations normalized to TOC. Nevertheless, the limited set of data available from this study prevented an attempt to model toxicity as a function of both of these factors. These findings reinforce the need to develop integrated models that include more than one binding phase, sulfide and organic carbon, and also other compartments of the system (e.g. interstitial water) to improve current methodologies for predicting copper toxicity based on sediment geochemical features.

Animals↗