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131.
132.
M. Xue K. K. Droegemeier V. Wong A. Shapiro K. Brewster F. Carr D. Weber Y. Liu D. Wang 《Meteorology and Atmospheric Physics》2001,76(3-4):143-165
133.
134.
In a laboratory experiment to simulate mine tailings disposal into a coastal inlet of British Columbia, initial rapid increases in dissolved iron, copper and lead were observed in the first three hours with subsequent slow decreases to background values within one month. Manganese and nickel increased slowly during the experiment while cadmium and zinc did not increase. 相似文献
135.
The two marine algae, Chaetomorpha brychagona and Enteromorpha crinita are found abundantly on the iron ore tailings of Tolo Harbour, Hong Kong, with a rather high level of various metals. Tissue analysis of the algae revealed that the contents of heavy metals (Fe, Mn, Pb and Zn) were higher than in the population collected from the two uncontaminated sites far away from the tailings. It was suggested that the algae were able to adapt to such a harsh environment with a comparatively high level of trace elements and the lack of basic nutrients. However, further studies are needed before any conclusion can be drawn. The delicate situation of the land-locked sea, Tolo Harbour, where the tailings and future heavy industrial site are situated, should not be overlooked. 相似文献
136.
The problem of the dynamic response of rigid embedded foundations subjected to the action of external forces and seismic excitation is analysed. It is shown that to calculate the response of rigid embedded foundations, or the response of flat rigid foundations subjected to non-vertically incident seismic waves, it is necessary to obtain not only the impedance matrix for the foundation, but also the forces induced by the incident seismic waves. Under these general conditions, rocking and torsional motion of the foundation is generated in addition to translation. The case of a two-dimensional rigid foundation of semi-elliptical cross-section is used as an example to illustrate the effects of the embedment depth and angle of incidence of the seismic waves on the response of the foundation. 相似文献
137.
Brendan?P.?Kelaher Jeffrey?S.?LevintonEmail author Jamina?Oomen Bengt?J.?Allen Wai?Hing?Wong 《Estuaries and Coasts》2003,26(6):1505-1516
We studied changes in macrobenthic communities following the environmental clean-up of metal-polluted (cadmium, nickel, and
cobalt) sediments in Foundry Cove, a small inlet within the Hudson River estuary of New York. We used a BACI-style experiment
to test the hypotheses that high levels of cadmium in sediments change macrobenthic assemblages relative to unpolluted areas,
and removal of metals (especially cadmium) by dredging will restore the benthos, such that benthic fauna in Foundry Cove are
not different from unpolluted areas. In 1984, prior to the restoration work, there were no significant differneces between
macrobenthic assemblages in polluted and unpolluted locations, indicating that cadmium had little effect on community structure.
The lack of an observed toxicity effect may have been caused by the compensatory evolution of resistance to cadmium in dominant
organisms. Six years after the restoration work and despite a substantial reduction in metal pollution, there were lower abundances
of oligochaetes, nematodes, and chironomids and a higher abundance of polychaetes at Foundry Cove relative to reference locations.
Correlative analyses identified greater sediment compaction caused by dredging at Foundry, Cove as a possible cause of faunal
differences. The results demonstrate that it is difficult to accurately predict, the effects of anthropogenic disturbances
and restorations in complex natural systems and that unforeseen side effects are inevitable. Documenting these unpredicted
effects and experimentally understanding their causes in past restorations will greatly improve the success and cost-effectiveness
of future projects of a similar type. 相似文献
138.
139.
南海颗粒物质的通量、组成及其与沉积物积累率的关系初探 总被引:15,自引:0,他引:15
通过大孔径时间系列沉积物捕获器的多年测量及对样品的多学科综合分析表明:南海北部与中部深海区1000m左右水深颗粒通量大约为90mg·m-2·d-1,在多数情况下,季风期间的颗粒通量有比较明显的增高。颗粒物主要组成为钙质生物来源的CaCO3、生物硅、岩源物质及海洋生物来源的有机质。颗粒通量与组成在水柱中的垂向变化表明,生源组分中CaCO3及有机质随深度具有较为明显的减少。颗粒物侧向运动可能是造成某些时段南海中部深层颗粒通量增加的主要原因。颗粒物质在进入深海沉积物之前,CaCO3、生物硅均在深层水与沉积物界面之间发生大量的溶解作用。有机质在沉降过程中的减少,一方面是由于硅质与钙质壳体的溶解而使结合在壳体内部的有机质随之溶解造成;另一方面可能与生物及生物地球化学作用有关。岩源物质除水柱沉降之外,还可以通过浊流等底层搬运机制进入南海北部及中部海盆,其中在南海北部这种搬运作用更为明显。 相似文献
140.
Thomas J. Jackson Terry L. Wade José L. Sericano James M. Brooks Jennifer M. Wong Bernardo Garcia-Romero Thomas J. McDonald 《Estuaries and Coasts》1998,21(4):718-730
The temporal distributions for six classes of trace organic contaminants (chlordanes, DDTs, dieldrin, PAHs, PCBs, and butyltins) in oysters from six Galveston Bay sites from National Oceanic and Atmospheric Administration’s National Status and Trends (NS&T) Mussel Watch Program are compared with other NS&T sites from the Gulf of Mexico as well as all NS&T sites of the United States (East Coast, West Coast, and Gulf of Mexico). Decreases in the median for the Gulf-wide concentration of chlordanes, dieldrin, and butyltins occurred during 1986–1994. The Gulfwide median concentrations of DDTs, PAHs, and PCBs exhibited a strong cyclic distribution with time. For Galveston Bay oysters, “high” concentration is defined as the concentration greater than the median plus one standard deviation for all Gulf of Mexico sites. The percentage of sites having high concentrations during 1986–1994 for Galveston Bay oysters are 49% for dieldrin, 45% for butyltins, 40% for chlordanes, 38% for PCBs, 30% for PAHs, and 21% for DDTs. For PCBs, 43% of Galveston Bay oyster samples analyzed over the first 9 yr have concentrations high enough for potential biological effects to be observed in oysters. The percentages in other agents were chlordanes (22%), butyltins (22%), dieldrin (5%), and PAHs (4%). National Academy of Science-proposed regulatory limits for oysters were exceeded in only 2% of Galveston Bay samples for DDTs and 1% for PCBs. All other contaminants were below proposed NAS limits. 相似文献