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1.
Thomas J. Fredette Joseph D. Germano Drew A. Carey Peggy M. Murray Paula G. Kullberg 《Chemistry and Ecology》2013,29(1-4):173-194
Geochemical analysis and visual inspection of cores collected from capped dredged material mounds revealed that in many cores, cap material was clearly distinguishable, both visually and chemically, from mound material. Contaminated dredged sediments were disposed in Long Island Sound eleven and seven years prior to sampling, and capped with uncontaminated dredged sediments. Core data provided no conclusive evidence of physical disturbance of, or chemical migration from, the contaminated mound sediments. Obvious chemical gradients of contaminant concentrations, which we propose are indicators of chemical migration, were not detected in the cores. Heterogeneity of the cap and mound sediments in some cores made the interface less distinct. We postulate that the preservation of spatial variability of sediment texture and associated contaminants observed within dredged material mounds is a result of the dredging process. Preservation of the textural and contaminant history of dredged sediments within finegrained cohesive cap materials provides evidence of the absence of physical or chemical disturbance. 相似文献
2.
Territorial defense and advertisement by footdrumming in bannertail kangaroo rats (Dipodomys spectabilis) at high and low population densities 总被引:3,自引:0,他引:3
Jan A. Randall 《Behavioral ecology and sociobiology》1984,16(1):11-20
Summary Behaviors associated with territorial defense of large dirt mounds by bannertail kangaroo rats (Dipodomys spectabilis) at high and low population densities are reported. Rats were observed for 640 h during three summers and one spring from 1980–1982 in SE Arizona.Bannertail kangaroo rats defended their territories by footdrumming, as a long-distance warning signal, and chasing as a closer-distance threat. They footdrummed on or near their mounds spontaneosly during the night, in response to neighbors' footdrums, and durint mound challenges. There were no sexual differences in footdrumming, and juveniles frequently performed the behavior. The low frequency sounds were within the auditory sensitivities of the rats and footdrumming patterns differed somewhat between individuals. A playback experiment provided preliminary evidence that rats can differentiate between the footdrums of neighbors and strangers. When a bannertail visited the mound of another bannertail the mound owner actively defended its mound and immediately chased the visitor away. Fighting and mound challenges occurred infrequently, and the uniformly dispersed distribution of mounds suggested an effort by rats to avoid mutual interference.When population densities were high, dispersing juveniles built new mounds, consequently, distances between mounds decreased. Rats responded by tolerating closer neighbors, spending more time active on their mounds, and visiting neighboring mounds less. Adults increased footdrumming rates at high population densities, but juveniles footdrummed at high rates regardless of the population size. 相似文献
3.
Thomas J. Fredette 《Chemistry and Ecology》1998,14(3):231-239
Since 1977, the US Army Corps of Engineers Disposal Area Monitoring System (DAMOS) has monitored New England's offshore dredged material disposal sites. DAMOS has shown that by using monitoring information to make management decisions, open water disposal of dredged sediments is possible with minimal environmental impact. Over the past two decades, DAMOS has answered many of the key questions about dredged material impacts. Yet the need for such a programme remains strong from both the technical and public interest perspectives. the programme continues to monitor projects that are extending our knowledge in the areas of deeper water capping, geotechnical behaviour of capping and capped materials, and biological response to contaminants. These investigations, along with the need for specific disposal site surveys, will continue to provide valuable technical information needed by the public, policy makers, and regulators to make critical decisions on dredged sediment management. 相似文献
4.
The Federal Institute of Hydrology has developed operating strategies in order to deal with dredged material within the scope of the Waterways and Shipping Administration. Sediments will be assessed based on certain quality parameters. The potential environmental impact at the source and relocation areas has to be evaluated in respect to ecological and economical issues. A coordinated sediment management plan for the Rhine River was commissioned. The most important contaminated sedimentation areas were identified, and special sedimentation areas were classified based on ecological impact or even risk. Proposals for economical and ecological strategies are discussed. Further developments for operational instructions dealing with sediments and dredged material in federal waterways are still being processed. The objectives of the river basin commissions as well as those of the stakeholders have to be met in an appropriate manner. In the framework of the analysis and impact of climate change on both sediment quantity and quality for optimizing sediment management, one or more dimensional hydraulic models will be applied. This will help gain a better insight into the understanding of contaminant transport in freshwater bodies. 相似文献
5.
Certain criteria must be satisfied before a licence for the deposition of dredged material at sea in UK waters is issued.
These relate to the chemical quality of the material, the quantity to be disposed of, its nature and origin, and its predicted
impacts at the disposal site. Although chemical analyses of dredgings provide an indication of the relative degrees of contamination,
they do not provide a measure of any resultant biological effects. A laboratory experiment was therefore designed to investigate
the effects of the degree of contamination and the role of burial associated with the deposition of dredged material on the
meiofauna. Estuarine nematode assemblages were exposed to the simulated deposition of uncontaminated, oxic intertidal mud
and anoxic sediments from the Mersey and the Tees estuaries, both of which were contaminated with heavy metals. The sediments,
which differed little in terms of grain size, were deposited in two different frequencies. Nematodes showed a clear species-specific
response to the experimental treatments, depending on the frequency of deposition and the chemical quality of the deposited
material (e.g. metal and oxygen concentrations). The response of nematode assemblages was mainly determined by the deposition
frequency rather than the type of sediment or the degree of contamination. The deposition of sediment in one large dose at
the beginning of the experiment caused more severe changes in assemblage structure than the same quantity deposited in several
smaller doses. Although lower than in uncontaminated mud, relatively high migration and survival rates in the contaminated
high-frequency treatments were observed. This may have been due to reduced bioavailability of metals and the tolerance of
estuarine nematodes to both metal contamination and the deposition of small sediment volumes at regular intervals. The observed
trends demonstrate the potential of small-scale laboratory experiments for testing the quality of contaminated dredged material
at the licensing stage, i.e. prior to the issue of a disposal licence.
Received: 11 February 2000 / Accepted: 26 June 2000 相似文献
6.
U.S. laws require that contaminant bioaccumulation potential be evaluated before dredged material can be recycled. Simple fugacity models, e.g. organic contaminant aqueous partition coefficient (K
oc)-derived theoretical bioaccumulation potential, are commonly used to estimate the partitioning of hydrophobic organic contaminants between sediment organic matter and organism lipid. K
oc-derived models, with or without the addition of a soot carbon term, did not accurately or consistently predict total polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls partitioning of eight sediments from ongoing dredging operations onto C18-coated filter paper. These models also failed to predict the partitioning of individual PAHs from these eight sediments. These data underscore the trade-offs between the ease of using simple models and the uncertainty of predicted partitioning values. 相似文献
7.
Remobilisation of contaminant metals from sediments can occur by chemical, biological or physical changes. This in turn can lead to contaminant fluxes to the porewaters and ultimately the water column. The aim of the research presented here is to document post-depositional controls on metal mobility and fluxes in a heavily metal-contaminated estuary. This will allow for an improved understanding of the impact of contaminated sediments on water quality from both a short-term and long-term perspective. Dulas Bay is situated on the east coast of Anglesey, North Wales, and receives polluted waters from Parys Mountain. Metals within Dulas Bay sediments show surface enrichment and variations in mineralogical form. Diagenesis clearly plays a role in post-depositional behaviour of the metals, forming sulphides and potentially carbonates. The presence of a dominant exchangeable/carbonate fraction, and elevated porewater metals, in this sulphidic system is significant and could indicate the presence of freshwater diagenesis, or, reflect the high levels of metals in the sediment. 相似文献
8.
The ocypodid crab Ilyoplax pingi, observed in Kanghwa I., Korea in 1992, builds a mound at the burrow entrance, by piling mud dug out from the burrow. The mounds were made by both waving and non-waving males, and by both ovigerous and non-ovigerous females. The burrow diameter at the widest part tended to be larger in crabs with mounds than in crabs without mounds, whereas the burrow depth was not different between them. The mound density increased in the late exposure period, when the crabs' surface activities declined. Mound removal and rebuilding experiments revealed that the presence of the mounds has the effect of keeping neighboring crabs away. 相似文献
9.
Seagrass colonise new areas via the dispersion of seeds or vegetative fragments. Independent of the manner of colonization,
habitat requirements need to be met for the successful establishment of seagrasses. Here we report on the colonization process
of Posidonia oceanica in a highly disturbed area: a gas pipeline trench at Capo Feto (SW Sicily, Italy). A trench dredged through a P. oceanica bed was back-filled with rubble added from dump barges leading to the formation of a series of rubble mounds on the seabed.
Over time, these mounds became colonised with P. oceanica. I>. In order to understand the pattern of P. oceanica colonization, shoot density was quantified over 3 years (2001–2003) on different mound locations (crests, sides, valleys).
Seagrass coalescence was observed only in valleys between mounds where shoot density averaged 133±50 shoots m−2, while values for sides and crests were significantly lower (30.5±14 and 5.8±2.6 shoots m−2, respectively). Although sediment accumulated on both crests and valleys, a significantly thicker sediment layer was recorded
in the valleys (9.8±0.4 cm) than on crests (1.1±0.2). Plaster dissolution rate (an indicator of the hydrodynamic regime) tended
to decrease from crests to valleys but even in the valleys, the currents were still higher than in the adjacent vegetated
control location. This pattern was constant over time and depths. This is the first study to report on P. oceanica vegetative recruitment on artificial rubble after a disturbance event. It appears that the valleys between the rubble mounds
are suitable for seagrass recruitment as sediment deposited between the rubble provides the necessary resources for plant
settlement and growth. Once the seagrass patches are established, they may start a positive feedback of attenuation of currents,
sediment accumulation and seagrass patch expansion. 相似文献
10.
11.
Canada, and other signatories to the London Convention 1972 on the prevention of marine pollution by dumping, are preparing to ratify a 1996 Protocol to this convention. Among the improvements to this international agreement, is a new process for the Assessment of Waste and Other Matter, which is to be adopted by signatory parties. the process includes a step in which material considered potentially acceptable for sea disposal must be characterized by chemical, physical and biological properties. Canada's interpretation and intended implementation of this characterization step is presented for the assessment of dredged sediments. This tiered testing approach involves using chemical screening limits for contaminants, and biological testing when screening levels are exceeded. Dredged material containing specified substances (e.g., cadmium, mercury, PAHs, PCBs, etc.) below or at screening levels would generally be considered of little environmental concern for disposal at sea. Wastes above the screening levels would require more detailed assessment before their suitability for disposal at sea could be determined. 相似文献
12.
Karel Essink 《Journal of Coastal Conservation》1999,5(1):69-80
Dredging and dumping of dredged sediments in estuarine and coastal waters may lead to increased turbidity and enhanced sediment
deposition at dump sites. This mainly affects primary production by phytoplankton, performance of visual predators (e.g. fish,
birds), and growth and survival of benthic organisms. This paper combines a compilation of literature information and results
of additional experimental studies on the effect of enhanced concentrations of suspended matter (SPM) on growth of bivalve
molluscs, and on survival of macro- and meiozoobenthos after dumping of dredged sediments. Furthermore, it focuses on non-toxic
dredged sediments only.
Release of nutrients from dredged sediments did, so far, hardly influence estuarine phytoplankton production. Increased turbidity
may affect dab as well as prey location by sandwich terns. Enhanced SPM-concentrations are unfavourable for young herring
and smelt. Growth of filter-feeding bivalves may be impaired, especially at SPM-concentrations >250 mg/l. Estuarine nematodes
can survive burial by 10 cm of dumped dredged sediment provided that its physical characteristics are similar to those of
the original sediment. Sessile benthos organisms such as mussels and oysters can cope with sediment deposition of only 1–2
cm. Other macrozoobenthos can survive sediment deposition of 20–30 cm. Recovery of benthos at a dump site will occur if the
interval between successive dumpings is sufficiently long.
Options for management of dumping of dredged sediments are described, relating to different locations of dump sites in estuarine
and coastal waters, to different seasons, and to the actual use (area and frequency) of dump sites. 相似文献
13.
M. Schratzberger N. Lampadariou P. J. Somerfield L. Vandepitte E. Vanden Berghe 《Marine Biology》2009,156(4):709-724
Physical disturbance is a key factor in controlling the spatial and temporal composition of shallow-water benthic communities.
Like shallow waters, deeper waters are increasingly subject to a range of anthropogenic disturbances, which can lead to significant
alterations in sedimentation patterns. These alterations often exceed naturally occurring changes. We used a combined analysis
of six independent data sets arising from large-scale field surveys and small-scale laboratory experiments to investigate
the effects of seabed disturbance on nematode communities. Disturbance response was documented as a function of disturbance
type (coastal development, dredged material disposal, bottom trawling, glacial fjord) and intensity (low, medium, high). Natural
and man-induced seabed disturbance exerted differential effects on exposed populations, generating changes in the taxonomic
(genus) and functional (feeding type) attributes of their assemblages. The genus composition of nematode assemblages from
geographically separate seas converged with increased level of various types of man-made disturbance. Assemblages present
along a gradient of natural disturbance in a glacial fjord followed an opposite response vector, suggesting that community
changes induced by anthropogenic activities, or experimental treatments simulating the principal impacts of these, inherently
differ from disturbance of natural origin. Changes in trophic diversity and structure were primarily driven by factors confounded
with physical disturbance, such as metal contamination. Coupling the results of analyses at multiple scales proved a useful
means of providing deeper insights into the general response of ecological communities to environmental change. 相似文献
14.
Canada, and other signatories to the London Convention 1972 on the prevention of marine pollution by dumping, are preparing to ratify a 1996 Protocol to this convention. Among the improvements to this international agreement, is a new process for the Assessment of Waste and Other Matter, which is to be adopted by signatory parties. the process includes a step in which material considered potentially acceptable for sea disposal must be characterized by chemical, physical and biological properties. Canada's interpretation and intended implementation of this characterization step is presented for the assessment of dredged sediments. This tiered testing approach involves using chemical screening limits for contaminants, and biological testing when screening levels are exceeded. Dredged material containing specified substances (e.g., cadmium, mercury, PAHs, PCBs, etc.) below or at screening levels would generally be considered of little environmental concern for disposal at sea. Wastes above the screening levels would require more detailed assessment before their suitability for disposal at sea could be determined. 相似文献
15.
Free-living marine, benthic nematodes quickly colonise sediments where physical forces are strong enough to suspend them into the water column. In the absence of such forces colonisation is much slower and is more likely to be affected by biological factors. The aim of the study was to investigate if nematodes disperse more readily in the presence of biological disturbance where physical disturbance is rare or non-existent. Amphipods are able to greatly rework sediments, and thereby induce disturbance to the infauna. A laboratory experiment with the amphipod Monoporeia affinis and nematodes from a low-energy, 30-m-deep location was conducted in mesocosms where the nematodes were given the choice to colonise azoic sediment at three amphipod densities, zero, low and high. Each area of azoic sediment in the mesocosms was divided into three equilateral sections from the nematode source, i.e. 10, 23 and 36 cm. At termination, after 7 weeks, there were no significant differences in nematode abundance and assemblage structure between treatments despite considerable biological disturbance created by the amphipods. The number of nematodes was 16%, 15% and 11% of the total numbers in the source at the three sections 10, 23 and 36 cm, respectively. There were distinct differences in the nematode community composition between distances, with the small surface-dwelling taxon Leptolaimus spp. being a rapid and the numerically dominant coloniser of the azoic sediments. Migration of nematodes over short distances is likely to be slow in the absence of strong physical forces. To our knowledge, this is the first paper ever that investigates the influence of macrofauna on nematode short-range migration.Communicated by L. Hagerman, Helsingør 相似文献
16.
Luca Giorgio Bellucci Mauro Frignani Stefano Lin Herbert Muntau 《Chemistry and Ecology》2005,21(6):425-439
Samples from 18 short sediment cores were analyzed for major and trace metals (Al, Fe, Ca, K, Mg, Mn, Si, Ti, Pb, Zn, Cu, Ni, and Cr), 210Pb, 137Cs, total organic carbon, grain size, and mineralogical composition to find the record of major environmental changes, either natural or anthropogenic, and to establish their chronologies. Some sediments are characterized by nearly constant composition over time, but others clearly show signs of an increasing marine influence, as an increase of the carbonate contents, after the opening of the Malamocco-Marghera Canal in 1969. These changes sometimes obscure the real pattern of pollutants and tracers, which is revealed by normalization against Al. Zn is the most important contaminant, with concentration factors up to 9.3 times the background level, and the most contaminated sediments are those within a few kilometers from the industrial district of Porto Marghera. 210Pb activity-depth profiles were used to calculate apparent accumulation rates that provide a basis for the assessment of metal fluxes. The sediments of several sites show a significant increase in anthropogenic metal contamination starting from the second decade of last century, with maximum inputs from 1930 to 1970. The decrease of heavy metal concentrations observed in surficial sediments of some sampling sites could be related to a recent reduction of pollutant inputs. 相似文献
17.
Mussels (Mytilus californianus, M. galloprovincialis) and other organisms sloughed from offshore oil platforms provide a food subsidy to benthic consumers and alter underlying soft bottom habitat by creating hard substrate. The removal of overlying platforms eliminates this food subsidy, but large shell mounds remain. The distribution, abundance, and population characteristics of mobile macroinvertebrates differed among shell mounds beneath existing offshore oil platforms, shell mounds at the former sites of offshore oil platforms, and soft bottom. Predatory and omnivorous echinoderm and mollusk species were more abundant and generally larger on shell mounds under platforms than on shell mounds without platforms. Omnivorous and deposit feeding echinoderms were the most abundant macroinvertebrate taxa sampled on mound-only sites. The brown rock crab (Cancer antennarius), known to have a strong preference for hard substrate, was significantly more abundant on shell mounds, with or without platforms, than adjacent soft bottom sites. Results suggest that the effects of platform removal differed among benthic species according to trophic level, degree of mobility, and substrate preference. Although the shell mound habitat persists after removal of platform structures, species abundance and the composition of the associated benthic community is altered by removal of the platform structure.Communicated by P.W. Sammarco, Chauvin 相似文献
18.
Wenzhong Tang Liu Sun Limin Shu Chuang Wang 《Frontiers of Environmental Science & Engineering》2020,14(6):104
19.
Wood charcoal production provides affordable energy in many developing countries and has substantially contributed to the economy through the provision of rural incomes. In several countries, charcoal production leads to overexploitation of forests due to inefficiencies in processing. This study was undertaken in central Laos to (1) examine and document traditional charcoal production systems; (2) investigate the production capacity, recovery efficiencies and economic gains of existing traditional charcoal production methods; (3) characterize the chemical properties of wood charcoal and investigate the potential for soil restoration and (4) investigate local charcoal producers' perception on forest degradation and their species preferences. Through a socio-economic survey, a cost-based method for economic valuation was undertaken on a range of charcoal production methods currently being used. Laboratory chemical analyses were performed on wood charcoal samples. Results indicated that the traditional mud charcoal mound was used by the majority (82%) of charcoal producers. Total charcoal production per production cycle varied between 400 (produced from 2.7 m3 of wood) and 1600 kg (produced from 18 m3 of wood), with a mean of 938 kg (±120) for traditional mud charcoal mounds. The volume of the traditional mud charcoal mounds correlated positively and significantly with total charcoal production (R 2 = 0.45, p?=?0.03), whereas correlated negatively and significantly with the recovery efficiency (R 2 = 0.58, p?=?0.01). On average, the local producers receive a total net benefit of 457,272 Lao kip (USD 57.2) in 17 days. We also identified a rice husk mound method of charcoal production, which may not encourage further deforestation while producing rice husk biochar that can be used for soil restoration. Furthermore, we found that there are significant differences (p < 0.05) between the sampled wood charcoals in chemical properties, indicating that the potential of using wood charcoal for the restoration of degraded soils varies from charcoal to charcoal. 相似文献
20.
A microcosm experiment was designed to evaluate the effects of the simulated deposition of uncontaminated dredged material
on nematode assemblages from estuarine intertidal mud. The main objective was to assess the ability of nematodes to migrate
vertically into native muddy and non-native sandy sediment deposited in different amounts and frequencies. Results from univariate
and graphical methods of data-evaluation revealed that nematodes were capable of migrating over a wide depth range from the
bottom mud layer into the top layer of deposited sand and mud. A diverse mud assemblage of nematodes was able to survive in
non-native fine sand for the experimental period of 2 mo. Multivariate analyses showed that the amount of deposit and the
frequency of deposition were interactive factors. A high amount of sediment deposited once at the beginning of the experiment
caused more severe changes in assemblage structure than the same amount deposited in more frequent but smaller doses. The
response of most species to the experimental treatments appeared to be an integrated response to the enhancing effect of food
input accompanying the deposit and the negative effect of burial. Upward migration of nematodes is a process which has often
been underestimated in its importance for recolonisation of areas where uncontaminated dredged material is deposited. Active
migration of nematodes can significantly affect the recovery of a dredgings disposal site.
Received: 29 July 1999 / Accepted: 17 January 2000 相似文献