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  • 1
    Electronic Resource
    Electronic Resource
    Toxicity of density separation media to Escherichia coli and Mycobacterium strain PC01: implications for density-separation of soils and sediments (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 43 (2003), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Separation of low-density sediment detritus in CsCl solution is a promising technique for benthic studies. The known toxicity of CsCl suggests the possibility of toxicity in the separated sediment. Fluoranthene biodegradation by Mycobacterium strain PC01 was used to probe microbial activity in sediment following density separation. Complete inhibition of biodegradation occurred in sediment previously contacted with CsCl media, but washing eliminated inhibition. Washing may not be preferable for subsequent study of the separated sediment, suggesting the need for less toxic media. We studied how various density separation media affected the viability of Escherichia coli to quantify toxicity. Although all media decreased viability, Nycodenz® and metrizamide were one to three orders of magnitude less toxic to bacteria than CsCl or Na2WO4. Toxicity was generally related to ionic strength. These results demonstrate that iodinated benzoic acids are superior to metal salts solutions for preserving biological activity on separated sediment or soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.2003.tb01057.x
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  • 2
    Electronic Resource
    Electronic Resource
    Combined Effects of Contaminant Desorption and Toxicity on Risk from PAH Contaminated Sediments (2004)
    350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Publishing, Inc.
    Risk analysis 24 (2004), S. 0 
    Details
    ISSN: 1539-6924
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: A strong inverse correlation was observed between the polycyclic aromatic hydrocarbon (PAH) mass fraction desorbed, a surrogate measure of bioavailability, and relative carcinogenicity, as quantified by potency equivalency factors (PEFs), for two study sediments from the New York/New Jersey Harbor estuary. Because compounds with the highest toxicity, such as dibenz(a,h)anthracene and benzo(a)pyrene (BAP), also tended to be the least rapidly and least extensively desorbed, the U.S. Environmental Protection Agency (EPA) default guidance may dramatically overestimate risk from exposure to PAH-contaminated soils or sediments. A “relative risk index” (RRI) was developed to account for the combined effects of compound-specific bioavailability and toxic potency in estimating excess cancer risk. Using this approach, estimated excess cancer risk may be diminished by as much as a factor of 159 times versus default EPA guidance. Also, the hierarchy of estimated risk between study sediments and among treatment fractions of study sediments differed using the two approaches, implying that the default approach may inaccurately determine site clean-up priorities. The percentage contribution of each potentially carcinogenic priority PAH to total excess cancer risk was computed under various scenarios. In each case, the contribution of BAP to total excess cancer risk was remarkably invariable, for example, ranging from 48% to 52% in one sediment, and 44% to 54% in the other, over four different exposure durations. These results suggest that BAP may be an excellent indexing compound for gauging relative exposure risk across sediments. Other important contributors to total excess cancer risk were benz(a)anthracene and dibenz(a,h)anthracene. Together, these three compounds comprised nearly 90% of total excess cancer risk from all PAHs in every scenario. This integrated RRI approach may enable regulators to more accurately gauge relative risks and make more informed sediment management decisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0272-4332.2004.00513.x
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  • 3
    Electronic Resource
    Electronic Resource
    Activity and distribution of bacterial populations in Middle Atlantic Bight shelf sands (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 44 (2003), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Spatiotemporal variation and metabolic activity of the microbial community were studied in coarse-grained Middle Atlantic Bight shelf sediments in relation to pools of dissolved and particulate carbon. Algal cells were present 8–〉70 μm) fraction of the sediment held the major share (61–98%) of benthic bacteria. Bacterial and algal cell abundances, exoenzymatic activity, and [DOC] generally showed higher values in May/July 2001 than in August/December 2000. Carbohydrates and proteins were hydrolyzed at potential rates of 1–12 nmol cm−3 h−1 (β-glucosidase) and 3–70 nmol cm−3 h−1 (aminopeptidase), respectively. Fluorescence in situ hybridization analyses of the benthic microbes assigned 45–56% of DAPI-stained cells to Eubacteria and less than 2% to Eukarya. The prokaryotic community was dominated by planctomycetes and members of the Cytophaga/Flavobacterium cluster. Near the sediment surface, iodonitrotetrazolium violet reducing cells, that are considered actively respiring, amounted to 15–29% of total bacteria. Despite a low organic content (particulate organic carbon 〈0.03%) and relatively low bacterial abundances (〈109 cm−3), the Middle Atlantic Bight shelf sediments showed organic matter turnover rates that are comparable to those found in organic-rich finer-grained deposits. Our findings suggest a high biocatalytic filtration activity in these coarse permeable sediments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.2003.tb01093.x
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  • 4
    Electronic Resource
    Electronic Resource
    Optimal foraging by deposit-feeding invertebrates: Roles of particle size and organic coating (1982)
    Springer
    Oecologia 52 (1982), S. 295-304 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Feeding experiments were conducted on marine, deposit-feeding benthic invertebrates to test the predictions of an optimal foraging model. Food item selection based on sediment particle size and presence or absence of an organic coating on particles was investigated. Animals displaying a wide range of feeding mechanisms were studied in particle size-selection experiments using artificial sediment of closely controlled size composition. Nine of 10 species from 4 phyla ingested smaller particles in greater proportions than the particles were present in the sediment. In experiments where animals fed on a mixture of two particle types, one with and one without a surface protein coating, 6 of 7 species from 3 phyla ingested preferentially the protein-coated beads. While these trends of selection of smaller particles and protein-coated particles follow qualitatively the predictions of the optimal foraging model, the animals did not ingest exclusively the preferred particle types. Mechanics of particle handling rather than behavioral responses to particle characteristics appear to offer the better explanation for the observed selection patterns. In particular, the results support strongly the recently proposed role of mucous adhesion in particle selection by deposit feeders. These and other results from studies of deposit feeders suggest that factors in addition to food item selection must be considered when testing the assumptions and predictions of optimal foraging theory. Specifically, feeding energetics are also affected by postfood-selection processes such as variation of ingestion rate. Furthermore, the effects of abiotic environmental factors on foraging behavior cannot be overlooked in evaluating the optimality of foraging behavior; variable water velocity affected differently the particle size selectivity of 3 sympatric polychaete species in these studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367951
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