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1.
Environmental change and oyster colonization within the Hudson River estuary linked to Holocene climate 总被引:4,自引:0,他引:4
S.?M.?CarbotteEmail author R.?E.?Bell W.?B.?F.?Ryan C.?McHugh A.?Slagle F.?Nitsche J.?Rubenstone 《Geo-Marine Letters》2004,24(4):212-224
Geophysical mapping and sampling data provide a record of changing environmental and faunal conditions within the Hudson River estuary during the mid- to late Holocene. On the shallow, broad marginal flats of the mesohaline Hudson, fossil oyster beds (Crassostrea virginica) are found exposed on the river bottom and buried by sediment. The shallowest beds are well imaged in chirp sub-bottom and side-scan sonar data and form discrete flow-perpendicular bands, 0.6–1.0 km wide and up to 3 km long, which cover 30% of the river bottom. Radiocarbon-dated sediment cores indicate oysters thrived within two time periods from ~500–2,400 and ~5,600–6,100 cal. years b.p. Sediment and physical property data indicate a changing depositional regime consistent with the oyster chronology. Similar changes in oyster presence are found in local shell midden sites of the Lower Hudson Valley as well as elsewhere along the Atlantic coast, and may reflect climatic controls associated with warm–cool cycles during the Holocene. Oysters flourished during the mid-Holocene warm period, disappeared with the onset of cooler climate at 4,000–5,000 cal. years b.p., and returned during warmer conditions of the late Holocene. The most recent demise of oysters within the Hudson at 500–900 cal. years b.p. may have accompanied the Little Ice Age. 相似文献
2.
Adrian Lawrence Marianne Stuart Colin Cheney Neil Jones Richard Moss 《Hydrogeology Journal》2006,14(8):1470-1482
Contaminant migration behaviour in the unsaturated zone of a fractured porous aquifer is discussed in the context of a study site in Cheshire, UK. The site is situated on gently dipping sandstones, adjacent to a linear lagoon historically used to dispose of industrial wastes containing chlorinated solvents. Two cores of more than 100 m length were recovered and measurements of chlorinated hydrocarbons (CHCs), inorganic chemistry, lithology, fracturing and aquifer properties were made. The results show that selecting an appropriate vertical sampling density is crucial both to providing an understanding of contaminant pathways and distinguishing whether CHCs are present in the aqueous or non-aqueous phase. The spacing of such sampling should be on a similar scale to the heterogeneity that controls water and contaminant movement. For some sections of the Permo-Triassic aquifer, significant changes in lithology and permeability occur over vertical distances of less than 1 m and samples need to be collected at this interval, otherwise considerable resolution is lost, potentially leading to erroneous interpretation of data. At this site, although CHC concentrations were high, the consistent ratio of the two main components of the plume (tetrachloroethene and trichloroethene) provided evidence of movement in the aqueous phase rather than in dense non-aqueous phase liquid (DNAPL). 相似文献
3.
Meretta Lake (Resolute Bay, Cornwallis Island, Nunavut, Canada) is a high arctic lake that received raw sewage for almost 50 years from the Canadian Department of Transport Base. The lake was sampled from 1968–72 during the International Biological Programme, as part of the Char Lake Project. As the number of users at the Transport Base declined throughout the 1990s, so too did the lake's nutrient levels, and Meretta Lake is now classified as oligotrophic. A previous diatom-based paleolimnological study revealed marked species assemblage shifts coincident with sewage inputs beginning in the late 1940s; however, because the core was taken at a time when nutrient levels were still relatively high (i.e., 1993), the diatom record did not yet track any signs of recovery. In this present study, we examined fossil diatom assemblages from a sediment core taken in 2001. Our results indicate a shift to the pre-impact diatom assemblages in the most recent sediments, indicating that the paleolimnological record is tracking the decreased nutrient inputs to this high arctic lake, and confirms that no significant lags exist in these largely ice-covered lakes. 相似文献
4.
5.
Upwelling plumes, superswells and true polar wander 总被引:1,自引:0,他引:1
Marianne Greff-Lefftz 《Geophysical Journal International》2004,159(3):1125-1137
6.
Active mud volcanoes on the upper slope of the western Nile deep-sea fan—first results from the P362/2 cruise of R/V Poseidon 总被引:1,自引:0,他引:1
Tomas Feseker Kevin R. Brown Cecile Blanchet Florian Scholz Marianne Nuzzo Anja Reitz Mark Schmidt Christian Hensen 《Geo-Marine Letters》2010,30(3-4):169-186
In February 2008, cruise P362/2 was undertaken aboard R/V Poseidon to the Giza and North Alex mud volcanoes (MVs) on the upper slope of the western Nile deep-sea fan. Emitted fluids were strongly depleted in chloride and rich in hydrocarbons, predominantly of thermogenic origin. In-situ sediment temperature measurements indicate extremely high and moderate levels of activity for the North Alex MV and Giza MV, respectively, and suggest rapid changes from dormant to active stages. Both the physical properties of core sediments (e.g., color and magnetic susceptibility), and their assemblages of micro- and nannofossils point to different sources for the two mud volcanoes. Biostratigraphic dating suggests source depths of 2,100–2,450 mbsf for the Giza MV and 1,150–1,550 mbsf for the North Alex MV. Very high temperatures of up to 70°C in shallow sediments at the North Alex MV can be explained only if the fluid source were warmer and deeper than the sediment source. 相似文献
7.
Marianne Alunno-Bruscia Henk W. van der Veer Sebastiaan A.L.M. Kooijman 《Journal of Sea Research》2009,62(2-3):43
The European Research Project AquaDEB (2007–2011, http://www.ifremer.fr/aquadeb/) is joining skills and expertise of some French and Dutch research institutes and universities to analyse the physiological flexibility of aquatic organisms and to link it to ecological and evolutionary processes within a common theoretical framework for quantitative bioenergetics [Kooijman, S.A.L.M., 2000. Dynamic energy and mass budgets in biological systems. Cambridge University Press, Cambridge]. The main scientific objectives in AquaDEB are i) to study and compare the sensitivity of aquatic species (mainly molluscs and fish) to environmental variability of natural or human origin, and ii) to evaluate the related consequences at different biological levels (individual, population, ecosystem) and temporal scales (life cycle, population dynamics, evolution). At mid-term life, the AquaDEB collaboration has already yielded interesting results by quantifying bio-energetic processes of various aquatic species (e.g. molluscs, fish, crustaceans, algae) with a single mathematical framework. It has also allowed to federate scientists with different backgrounds, e.g. mathematics, microbiology, ecology, chemistry, and working in different fields, e.g. aquaculture, fisheries, ecology, agronomy, ecotoxicology, climate change. For the two coming years, the focus of the AquaDEB collaboration will be in priority: (i) to compare energetic and physiological strategies among species through the DEB parameter values and to identify the factors responsible for any differences in bioenergetics and physiology; and to compare dynamic (DEB) versus static (SEB) energy models to study the physiological performance of aquatic species; (ii) to consider different scenarios of environmental disruption (excess of nutrients, diffuse or massive pollution, exploitation by man, climate change) to forecast effects on growth, reproduction and survival of key species; (iii) to scale up the models for a few species from the individual level up to the level of evolutionary processes. 相似文献
8.
The attenuation of chemical elements in acidic leachates from coal mineral wastes by soils 总被引:1,自引:0,他引:1
The chemical attenuation of acidity and selected elements (aluminum, arsenic, cadmium, cobalt, chromium, copper, fluorine,
iron, manganese, nickel, and zinc) in acidic leachates from coal mineral wastes by four natural subsurface soils has been
investigated using laboratory column methods Leachate solutions were allowed to percolate through the soils under simulated
natural flow conditions, and the elemental concentrations in the influents and effluents were measured periodically Elemental
retentions were substantial for all species except managanese, which was eluted in excess from all soils except the most calcareous
Two processes appeared to operate in decreasing influent concentrations: (1) precipitation of solid phases caused by increased
pH of the leachate as it percolated through the soil, and (2) adsorption of elements onto exchange and sorption sites naturally
present in the soil and on iron and aluminum oxide precipitates formed in situ from leachate components because of the increased
pH The soil property most important in retention was its alkalinity Thus, carbonaceous soils provide the best control material
for acidic leachates from coal mineral wastes. Results show that natural soils can substantially reduce pollutant fluxes to
the environment from acidic coal waste dumps and should be considered when selecting waste disposal sites
Performed under the auspices of the U.S. Department of Energy 相似文献
9.
10.
Considerable interest exists inthe potential role climate may play in human healthissues, especially regarding the effect of climatechange on vector-borne disease. The Aedesaegypti mosquito, the principal vector for dengue,considered the most important vector-borne viraldisease in the world, is particularly susceptible toclimate variability and climatic change. Here wepresent a modeling analysis focusing on global-scaleassociations between climate and the development,potential distribution, and population dynamics ofAe. aegypti. We evaluate the model by comparingand contrasting model data with observed mosquitodensities. There is good agreement between theobserved and modeled global distribution of themosquito; however, the model results suggest thepotential for increased latitudinal distributionsduring warmer months. Seasonal fluctuations inmosquito abundance also compare well to observed data. Discrepancies possibly reflect the relatively lowresolution of the climate data and model output andthe inability of the model to account for localmicroclimate effects, especially in coastal areas.Future modeling efforts will involve study ofinterannual variability in mosquito dynamics. 相似文献