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1.
The first analysis of sterols in Antarctic marine sediment cores (Bransfield Strait and McMurdo Sound) is reported here. The isolated sterols in the sediments from Bransfield Strait are comprised mainly of dinosterol (4,23,24-trimethyl-5cholest-22-en-3β-ol), coprostanol (5β-cholestan-3β-ol) and epicoprostanol (5β-cholestan-3-ol) and trace amounts of cholesterol (cholest-5-en-3β-ol). The sediment cores of McMurdo Sound also contain small quantities of coprostanols in addition to large amounts of marine sterols. Dinosterol is a known dinoflagellate chemical marker, whereas coprostanols are currently being used as tracers for sewage contamination. However, sterol composition in Antarctic sediments is expected to be atypical of sewage input and probably different from those of temperate and tropical zones. The coprostanols must therefore arise from the feces of marine mammals, most probably whales which use the region for feeding and spawning. Based on the results of this study, caution should be exercised in the use of coprostanol to estimate the amount of sewage-derived organic matter transported away from impacted coastal areas. 相似文献
2.
Elemental carbon and nitrogen levels and isotope ratios were assessed in different biological compartments of a Northwest (NW) Mediterranean bay to trace the various sources of nutrient input from natural (river runoffs) and anthropogenic (harbor outflows, fish farms and urban sewage outfall) sources. Samples from transplanted mussels and natural sea grass communities (Posidonia oceanica leaves and epiphytes) were harvested from different locations throughout the bay during the touristic summer and rainy seasons. The results from the nitrogen analysis revealed that sewage and harbor outflow promote higher nitrogen levels, enrichment of 15N in the tissues, and a higher seasonal variability in sea grass and epiphytes. In mussel tissues, the δ15N was also influenced by sewage and harbor outflow, whereas δ13C was influenced by terrestrial inputs. These results suggest that natural and anthropogenic nutrient inputs have a temporary and localized influence and affect the sensitivity of natural isotopic ratios to changes in hydrologic conditions, especially to rain and tourism. 相似文献
3.
McMurdo Station is the United States Antarctic Research Program's (USARP) centre for scientific and logistical support for most of the continent and is the largest settlement in Antarctica. Over 30 years of human presence with shipping, air-transport, scientific, and municipal activities have resulted in severe but localized nearshore marine benthic pollution. This review will summarize the results of 3 years of research which has documented concentrations of chemical contaminants, changes in community patterns, and the toxicity of sediments to invertebrate species and infaunal communities. The primary contaminants are petroleum hydrocarbons in the sediments of Winter Quarters Bay, the site of shipping activities and a former dumpsite. Total hydrocarbon levels in sediments in Winter Quarters Bay were comparable to the most polluted harbours in temperate latitudes. However, a steep gradient of pollution existed: stations less than 1 km away were nearly pristine. Benthic invertebrate communities changed dramatically along this contamination gradient. The results of both field and laboratory bioassay experiments with contaminated sediments found that biological changes observed in benthic communities around McMurdo Station were most likely caused by hydrocarbons, PCBs, and PCTs. A primary goal of polar pollution research is to determine the response and tolerance of Antarctic biota to physical and chemical anthropogenic disturbance, and the mitigation of negative effects. To this end, future work should include continued monitoring of changes in chemical and community patterns, studies of the physiological responses of Antarctic invertebrates to chemical contamination, and further comparisons of anthropogenic and natural disturbances to benthic communities. 相似文献
4.
The majority of coastal Antarctic stations release untreated sewage into the near-shore marine environment. This study examined bacterial reproduction within the temporary sewage-holding tanks of Rothera Research Station (Adelaide Island, Antarctic Peninsula) and monitored sewage pollution in the local marine environment. By continuously flushing the sewage-holding tanks with cold seawater we inhibited microbial reproduction and decreased the numbers of bacteria subsequently released into the sea by >90%. The widespread use of this simple method could significantly reduce the numbers of faecal coliform and other non-native microorganisms introduced into the Antarctic marine environment. 相似文献
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6.
A benthic habitat along the coast of McMurdo Station in the Ross Sea, Antarctica is enriched by sewage from the station and altered by hydrocarbons and heavy metals in an adjacent historic dumpsite. We report on 10 years of change in the benthic communities from 1988 to 1998 and compare enrichment effects at Australia's Casey Station, East Antarctica. Despite being 14 km apart, reference communities upcurrent and downcurrent of McMurdo Station remained closely similar over time, dominated in all years by a tube building polychaete, Spiophanes tcherniae. The community bordering McMurdo Station was generally a third as abundant as communities at the reference sites over the decade of sampling, although diversity was as high or higher, except in the most contaminated areas. In 1992, organic enrichment of the outfall community intensified and within the year, the opportunistic polychaetes Aphelochaeta sp., Ophryotrocha notialis, Capitella perarmata, and Leitoscoloplos kerguelensis became dominant. Since 1996, two of the three enriched communities have increased in resemblance to the reference communities. Given the observed responsiveness of the benthos to the outfall so far, further changes are anticipated within the year following implementation of sewage treatment in 2003. Organic enrichment by McMurdo Station has had a greater impact on benthic community structure than at Australia's Casey Station. 相似文献
7.
Nikolaus Gussone Gerald Langer Markus Geisen Blair A. Steel Ulf Riebesell 《Earth and Planetary Science Letters》2007,260(3-4):505-515
Four species of marine calcifying algae, the coccolithophores Calcidiscus leptoporus, Helicosphaera carteri, Syracosphaera pulchra and Umbilicosphaera foliosa were grown in laboratory cultures under temperatures varying between 14 and 23 °C, and one species, C. leptoporus, under varying [CO32−], ranging from 105 to 219 μmol/kg. Calcium isotope compositions of the coccoliths resemble in both absolute fractionation and temperature sensitivity previous calibrations of marine calcifying species e.g. Emiliania huxleyi (coccolithophores) and Orbulina universa (planktonic foraminifera) as well as inorganically precipitated CaCO3, but also reveal small species specific differences. In contrast to inorganically precipitated calcite, but similar to E. huxleyi and O. universa, the carbonate ion concentration of the medium has no statistically significant influence on the Ca isotope fractionation of C. leptoporus coccoliths; however, combined data of E. huxleyi and C. leptoporus indicate that the observed trends might be related to changes of the calcite saturation state of the medium. Since coccoliths constitute a significant portion of the global oceanic CaCO3 export production, the Ca isotope fractionation in these biogenic structures is important for defining the isotopic composition of the Ca sink of the ocean, one of the key parameters for modelling changes to the marine Ca budget over time. For the present ocean our results are in general agreement with the previously postulated and applied mean value of the oceanic Ca sink (Δsed) of about − 1.3‰, but the observed inter- and intra-species differences point to possible changes in Δsed through earth history, due to changing physico-chemical conditions of the ocean and shifts in floral and faunal assemblages. 相似文献
8.
Based on the stable isotopic analysis of more than 1000 samples of planktonic and benthic foraminifers from ODP Site 1148
in the northern South China Sea (SCS), the oxygen isotope stratigraphy has been applied to the last 3 million years for the
first time in the SCS. Furthermore, the paleoceanographic changes in the northern SCS during the last 6 million years have
been unraveled. The benthic foraminiferal δ18O record shows that before δ3.1 Ma the SCS was much more influenced by the warm intermediate water of the Pacific. The remarkable
decrease in the deepwater temperature of the SCS during the period of 3.1-2.5 Ma demonstrates the formation of the Northern
Hemisphere ice-sheet. However, the several sea surface temperature (SST) reductions during the early and middle Pliocene,
reflected by the planktonic foraminiferal δ18O, might be related to the ice-sheet growth in the Antarctic region. Only those stepwise and irreversible SST reductions during
the period of δ2.2-0.9 Ma could be related to the formation and growth of the Northern Hemisphere ice-sheet. 相似文献
9.
McPherson CA Tang A Chapman PM Taylor LA Gormican SJ 《Marine pollution bulletin》2002,44(12):1405-1414
Investigation of sediment contamination associated with a marine sewage outfall in Victoria (BC, Canada) found elevated concentrations of 1,4-dichlorobenzene (1,4-DCB). Juvenile polychaete worm (Neanthes) growth was significantly reduced at or near the outfall, roughly corresponding to elevated 1,4-DCB concentrations. There are few data on 1,4-DCB toxicity to marine organisms and no published literature on its toxicity to benthic marine organisms. To determine whether reduced polychaete growth (measured as dry weight) was due to 1,4-DCB exposure, a laboratory investigation was conducted. Uncontaminated marine sediment was spiked with 1,4-DCB and juvenile Neanthes were exposed in 20-d sublethal toxicity tests. There were no adverse effects on survival at any test concentration; mean survival was 80–100%. Statistically significant decreases in average dry weight only occurred at the highest 1,4-DCB concentration (19,900 μg/kg, dry weight); this represented a 1,4-DCB concentration more than 10 times higher than previously measured at the outfall (1710 μg/kg, dry weight). There were no adverse effects on survival or dry weight at the range of concentrations previously measured in sediments from the vicinity of the outfall. 相似文献
10.
Alexander M. Piotrowski Steven L. Goldstein Sidney R. Hemming Richard G. Fairbanks David R. Zylberberg 《Earth and Planetary Science Letters》2008,272(1-2):394-405
While ocean circulation is driven by the formation of deep water in the North Atlantic and the Circum-Antarctic, the role of southern-sourced deep water formation in climate change is poorly understood. Here we address the balance of northern- and southern-sourced waters in the South Atlantic through the last glacial period using neodymium isotope ratios of authigenic ferromanganese oxides in thirteen deep sea cores from throughout the South Atlantic. The data indicate that northern-sourced water did not reach the Southern Ocean during the late glacial, and was replaced by southern-derived intermediate and deep waters. The high-resolution neodymium isotope record (~ 300 yr sample spacing) from two spliced deep Cape Basin sites indicates that over the last glacial period northern-sourced water mass export to the Southern Ocean was stronger during the major Greenland millennial warming intervals (and Southern Hemisphere cool periods), and particularly during the major interstadials 8, 12, and 14. Northern-sourced water mass export was weaker during Greenland stadials and reached minima during Heinrich Events. The benthic foraminiferal carbon isotopes in the same Cape Basin core reflect a partial control by Southern Hemisphere climate changes and indicate that deep water formation and ventilation occurred in the Southern Ocean during major Greenland cooling intervals (stadials). Together, neodymium isotopes and benthic carbon isotopes provide new information about water mass sourcing and circulation in deep Southern Ocean waters during rapid glacial climate changes. Combining carbon and neodymium isotopes can be used to monitor the relative proportion of northern- and southern-sourced waters in the Cape Basin to gain insight into the processes which control the carbon isotopic composition of deep waters. In this study we show that deep water formation and circulation was more important than biological productivity and nutrient regeneration changes for controlling the carbon isotope chemistry of Antarctic Bottom Water during millennial-scale glacial climate cycles. This observation also lends support to the hypothesis that ocean circulation is linked to interhemispheric climate changes on short timescales, and that ventilation in the glacial ocean rapidly switched between the northern and Southern Hemisphere on millennial timescales. 相似文献
11.
浮游生物是湖泊食物网的重要组成,其碳、氮稳定同位素能够反映元素地球化学循环和食物来源的波动,是了解水域生态系统结构变化的重要手段之一.本文选取云南4个不同类型湖泊,开展浮游生物碳、氮稳定同位素组成(δ13C、δ15N)的季节变化与湖泊对比研究.大型深水湖泊(抚仙湖和阳宗海)中,浮游植物δ13C值在夏、秋季(-20.34‰±1.98‰)显著高于冬、春季(-28.00‰±2.51‰),反映夏秋季藻类生长速率较高、HCO3-无机碳源利用增多等的影响.而小型浅水湖泊(长桥海和大屯海)中浮游植物δ13C值在夏季最高(-21.24‰±0.88‰),可能与雨季流域输入增强、陆源有机质占比增加有关.4个湖泊浮游生物δ15N值具有一致的变化特征,春季显著高于其他季节.分析表明,云南地区雨季以面源污染为主向旱季以点源污染为主的转变,导致氮素营养盐季节性来源差异,并通过生物吸收作用影响了浮游生物δ15N值的季节变化.在浮游动物与浮游植物的稳定同位素差值(即富集度)方面,营养水平高的小型浅水湖泊中δ13C富集度为1.61‰±0.90‰、δ15N富集度为2.71‰±1.22‰,显著小于营养水平低的大型深水湖泊(分别为2.60‰±0.98‰和4.19‰±1.25‰),表明随着湖泊营养水平的增加,浮游动物更多地以浮游植物为食,导致有机碳在不同营养级之间的传输过程中具有更强的耦合作用,且相邻营养级之间具有更低的δ15N富集度特征. 相似文献
12.
P. A. Ayres 《Marine pollution bulletin》1977,8(12):283-285
Samples of bottom sediment taken in an area used for marine dumping of sewage sludge were examined for the presence of Escherichia coli and coliform bacteria. Using a simple membrane filtration technique, an extensive network of stations was sampled and examined at sea in under two days. The results obtained were in good agreement with seabed drifter and radioactive tracer studies, and suggest that the use of bacterial indices may be a useful means of estimating the distribution of sewage sludge solids in bottom sediments. 相似文献
13.
James P. Howington Gordon A. McFeters James P. Barry James J. Smith 《Marine pollution bulletin》1992,25(9-12):324-327
The spatial distribution and movement of the sewage plume from McMurdo Station, Antarctica, was investigated in the ocean under the early summer ice. Samples of seawater were obtained via holes drilled through the ice and analysed for coliform bacteria. Ocean currents were also examined to determine their effect on the movement of the plume. High densities of coliform bacteria were found along the ca. 1 km shoreline of McMurdo Station and the plume extended 200–300 m seaward. The relocation of the outfall from a surface configuration to the subsurface (11 m deep) had little influence on the distribution of the plume that sometimes reached the seawater intake station, 400 m to the south. Ocean current measurements in the study area confirmed that, while the prevailing advection was to the north and away from the intake area, episodic reversals of flow at some current meter stations coincided with pulses of sewage that moved into the intake. These findings support the use of bacterial indicators as one means to map the distribution and movement of recent sewage contamination in cold (−1.8°C) seawater and provides evidence that the disposal and movement of domestic wastes in coastal polar environments deserves attention. 相似文献
14.
Cees Van Der Burgt 《Marine pollution bulletin》1994,29(6-12):296-299
Protection of the sea has received much political attention—for example, at successive North Sea Conferences environmental ministers have formulated a stringent policy with the aim of reducing pollution in the north-east Atlantic. In the past this area received many substances from many sources, but gradually intergovernmental action since 1972 in the Oslo and Paris Conventions has succeeded in tracing the major sources and understanding the effects of these inputs on the marine environment. After long discussion, many dumpings and discharges have been ended because they were considered harmful to the marine environment. Dredging activities were included in the discussions but they may be regarded as being a special case compared with many other disposals.
In general, clean dredged material for sea disposal offers no problems, although restrictions may be caused by physical impacts, mainly to habitats for living organisms. However, this material also has positive, often even beneficial uses. In contrast, contaminated material disposal is restricted and the internationally accepted rule is that the material should not create hazards to human health, harm living resources and marine life or damage amenities or interfere with other legitimate uses of the sea. There are in principle three options for dealing with polluted sediments: doing nothing, remedial action in situ, removal of the contaminated material; occasionally treatment is a possibility. The distinction has been made between the disposal of industrial waste, sewage sludge or dredged material. Industrial waste disposal is now prohibited; sewage sludge may be dumped until 31 December 1998, although dredged material may still be stored at sea under certain conditions. The Oslo Convention 1972 decided with regard to dredged material: that pollution has to be tackled at the source; dumping at sea is forbidden, although dredged materials may be excluded from this; land disposal prevails, although in several countries there is a growing resistance to disposal on land; there should be a precautionary approach against marine disposal; a stand-still principle should be followed where the quantities disposed in a certain year should not be exceeded nor should the quality of the receiving water be reduced; marine disposal should be phased out and, where appropriate, time-limits set; and the polluter pays.
Dredged material is regarded as polluted and as a consequence may in general not be disposed of at sea when it contains substances listed in the Annexes of the Convention. Exceptions to this are indicated by the terms ‘a trace contaminant’, ‘rapidly rendered harmless’ or ‘significant amounts’. Therefore, to achieve uniformity in the application of the Convention, guidelines have been prepared by a joint London Dumping Convention/Oslo Commission working group of experts on dredged material. Several characteristics must be considered when choosing a site for marine disposal and interests such as beach recreation, sport and commercial fishing, nature, cultural or historical interests, navigation, military interests and cables and pipelines should be taken into account. Also the capacity of the area to assimilate disposed matter per time unit must not be exceeded, especially in low energy areas. It is considered that in discussions of the environmental aspects of dredging it is important that associations such as PIANC argue for safe and economic navigation. 相似文献
15.
Habitat-forming organisms are frequently used as biomonitors in marine environments due to a widespread ability to accumulate toxic contaminants. Few studies, however, have considered the consequences of these accumulated contaminants on the abundant and diverse fauna associated with these habitats. In this review, we summarize research which has investigated the contamination of biogenic habitats (including seagrasses, macroalgae, ascidians, sponges and bivalve reefs) and the impact of this contamination on the habitat use, feeding behaviour and survival of associated epifauna. In many cases, ecological impacts upon epifauna are not simply predicted by levels of contamination in their habitat, but are determined by the foraging, feeding and reproductive behaviours of the inhabiting organisms. Thus, a thorough understanding of these ecological processes is essential in order to understand the effects of contaminants upon epifaunal communities. The scope of biomonitoring studies which assess the contamination of biogenic habitats should be expanded to include an assessment of potential effects upon associated epifauna. When combined with manipulative field experiments such an approach would greatly assist in our understanding of indirect effects of contaminants in these important benthic habitats. 相似文献
16.
The osmium (Os) concentration and187Os/186Os ratio of several recent, marine, organic-rich sediment samples from three widely separated sites have been measured. Os concentrations range from 0.095 to 0.212 ppb and187Os/186Os ratios range from 8.2 to 8.9. The calculated fraction of hydrogenous Os exceeds 78% in all samples. Thus, the187Os/186Os ratio of these samples reflects Os isotopic composition of seawater. The small range in measured187Os/186Os ratio indicates that the Os isotopic composition at these sites is fairly homogeneous. The large magnitude of the Os burial flux at these sites indicates the Os burial in association with organic-rich sediments is an important sink in the marine cycle of Os. These data also suggest that ancient organic-rich sediments may provide a record of past variations in the Os isotopic composition of seawater. 相似文献
17.
Hughes KA 《Marine pollution bulletin》2004,49(9-10):850-853
Despite Antarctica being the largest pristine wilderness on Earth, many coastal Antarctic research stations release untreated sewage waste into the marine environment, which may have negative effects on local wildlife. In February 2003 a sewage treatment plant was installed at Rothera Research Station (Adelaide Island, Antarctic Peninsula). After one year of operation the sewage treatment plant had dramatically reduced the microbiological pollution in the near-shore marine environment around the outfall and seawater quality conformed to European Union Bathing Water Standards. 相似文献
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19.
Isotopic evidence of subtle nutrient enrichment in mangrove habitats of Golfo Dulce,Costa Rica 
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下载免费PDF全文 Mangroves are of great ecological and socio‐economic importance, yet they are under threat from urban development on the southern Pacific coast of Costa Rica. To test for possible nutrient‐related impacts, we compared water‐column nutrient concentrations, C and N stable isotope values and other environmental variables between mangroves with known sewage loading (three “nutrient loaded” locations) and those without such loading (three “reference” locations). Instantaneous nutrient concentrations were low at all locations, Secchi depth was greater at reference locations, and chlorophyll concentrations were higher at nutrient loaded mangroves. Suspended matter did not vary between reference and nutrient loaded mangroves, and nor did bivalve and algal δ13C and δ15N values. Enrichment of δ15N and δ13C of red mangrove leaves at the nutrient loaded locations is attributed to pulsed inputs of materials that were not detected in the instantaneous nutrient data. We provide evidence of isotopic enrichment at nutrient loaded locations from mangrove material and recommend that adequate waste water treatment be carried out on all anthropogenic discharges into this vulnerable marine system. 相似文献
20.
The Vendian record of Sr and C isotopic variations in seawater: Implications for tectonics and paleoclimate 总被引：26，自引：0，他引：26
Alan J. Kaufman Stein B. Jacobsen Andrew H. Knoll 《Earth and Planetary Science Letters》1993,120(3-4):409-430
New Sr and C isotopic data, both obtained on the same samples of marine carbonates, provide a relatively detailed record of isotopic variation in seawater through the latest Proterozoic and allow, for the first time, direct correlation of these isotopic changes in the Vendian ( 540–610 Ma). The strong isotope variations determined in this study record significant environmental and tectonic changes. Together with a fairly poorly constrained Nd isotopic record, the Sr and C isotopic records can be used to constrain rates of erosion, hydrothermal alteration and organic C burial. Further, comparison of these records with those of the Cenozoic permit investigation of the general relationship between global tectonics and continental glaciation. In particular, results of this study show a very large change in the 87Sr/86Sr of marine carbonates from low pre-Vendian ( > 610 Ma) values ( 0.7066) to high Middle Cambrian values ( 0.7090). This change is greater in magnitude than the significant increase in seawater 87Sr/86Sr through the Cenozoic. Both changes are attributed to high erosion rates associated with continent-continent collisions (Pan-African and Himalayan-Tibetan). In the latest Proterozoic these high erosion rates, probably coupled with high organic productivity and anoxic bottom-water conditions, contributed to a significant increase in the burial rate of organic C. Ice ages mark both the Neoproterozoic and Cenozoic, but different stratigraphic relationships between the Sr isotopic increase and continental glaciation indicate that uplift-driven models proposed to explain Cenozoic climatic change cannot account for the latest Proterozoic ice ages. 相似文献