Profiles of Fecal Porphyrins in River Otters Following the Exxon Valdez Oil Spill     

Christopher Taylor  Lawrence K. Duffy  R. Terry Bowyer  Gail M. Blundell 《Marine pollution bulletin》2000,40(12):422-1138

Median levels of Coproporphyrin III (Copro III) in fecal samples of river otters (Lontra canadensis) collected from an oiled area in Prince William Sound, Alaska, USA, during 1990 were significantly higher than in samples collected from the same oiled area during 1996 (p=0.011, one way analysis of variance), a nonoiled reference area in Prince William Sound during 1996 (p=0.002) and a reference area in southeast Alaska during 1998 (p=0.004). An overall test of significance that combined probabilities from the statistical analysis of this porphyrin study with those from other biomarker studies revealed a significant difference in physiological response of river otters between oiled and nonoiled areas of the Sound for 1990 (p < 0.01). We demonstrated that changes in levels of fecal porphyrins may serve as a biomarker that may contribute to a health assessment of wild river otters.  相似文献   

The Ocean Circulation of Chatham Sound,British Columbia,Canada: Results From Numerical Modelling Studies Using Historical Datasets     

Yuehua Lin  David B. Fissel 《大气与海洋》2018,56(3):129-151

Chatham Sound, a semi-enclosed inland sea located off northern British Columbia, is an important waterway due to many proposed industrial activities related to the Port of Prince Rupert, along with its high levels of marine productivity. The oceanographic forcing in Chatham Sound is complex due to a combination of large tides, seasonally strong winds, and large freshwater discharges. Although much oceanographic data have been collected over the past six decades, past studies of the oceanographic regime of the full Chatham Sound area have been very limited. Using these extensive forcing datasets, high-resolution three-dimensional numerical modelling using the Coastal Circulation model for Sediment transport was conducted to investigate the tidal and wind-driven currents in the stratified waters of Chatham Sound. The numerical study shows the progression of the river-dominated lower salinity near-surface waters being advected northward, especially on the eastern side of Chatham Sound, with more saline waters on the western side of the Sound, especially in areas of exchanges with the waters of Hecate Strait through side channels. These surface circulation results are in good agreement with the large-scale representation of the outer diffuse Skeena River plume as seen in high-resolution Landsat satellite imagery. The model was operated over a representative year with four seasonal model runs. Southern Chatham Sound was found to be dominated by large tidal currents. Seasonal variations of residual flow were also investigated. Significant correlation between non-tidal current speeds and Skeena River discharges was found in the Skeena River delta area and through narrow tidal channels in southern Chatham Sound. In other offshore areas, non-tidal currents were found to be constrained near the surface and driven mainly by winds.  相似文献   

Isotopic and geochemical constraints on the age and origin of granitoids from the central Mawson Escarpment, southern Prince Charles Mountains, East Antarctica   总被引：1，自引：0，他引：1  

S. D. Boger  R. Maas  C. M. Fanning 《Contributions to Mineralogy and Petrology》2008,155(3):379-400

Granitoids from the central Mawson Escarpment (southern Prince Charles Mountains, East Antarctica) range in age from Archaean to Early Ordovician. U–Pb dating of zircon from these rocks indicates that they were emplaced in three distinct pulses: at 3,519 ± 20, 2,123 ± 12 Ma and between 530 and 490 Ma. The Archaean rocks form a layer-parallel sheet of limited extent observed in the vicinity of Harbour Bluff. This granitoid is of tonalitic-trondhjemitic composition and has a Sr-undepleted, Y-depleted character typical of Archaean TTG suites. ε_Nd and T_DM values for these rocks are −2.1 and 3.8 Ga, respectively. Subsequent Palaeoproterozoic intrusions are of granitic composition (senso stricto) with pronounced negative Sr anomalies. These rocks have ε_Nd and T_DM values of −4.8 and 2.87 Ga, indicating that these rocks were probably melted from an appreciably younger source than that tapped by the Early Archaean orthogneiss. The remaining intrusions are of Early Cambrian to Ordovician age and were emplaced coincident with the major orogenic event observed in this region. Cambro–Ordovician intrusive activity included the emplacement of layer-parallel pre-deformational granite sheets at approximately 530 Ma, and the intrusion of cross cutting post-tectonic granitic and pegmatitic dykes at ca. 490 Ma. These intrusive events bracket middle- to upper-amphibolite facies deformation and metamorphism, the age of which is constrained to ca. 510 Ma—the age obtained from a syn-tectonic leucogneiss. Nd–Sr isotope data from the more felsic Cambro–Ordovican intrusions (SiO₂ > 70 wt%), represented by the post-tectonic granite and pegmatite dykes, suggest these rocks were derived from Late Archaean or Palaeoproterozoic continental crust (T_DM ∼ 3.5–2.3 Ga, ε_Nd ∼ −21.8 to −25.9) not dissimilar to that tapped by the Early Proterozoic intrusions. In contrast, the compositionally more intermediate rocks (SiO₂ < 65 wt%), represented by the metaluminous pre-tectonic Turk orthogneiss, appear to have melted from a notably younger lithospheric or depleted mantle source (T_DM = 1.91 Ga, ε_Nd ∼ −14.5). The Turk orthogneiss additionally shows isotopic (low ¹⁴³Nd/¹⁴⁴Nd and low ⁸⁷Sr/⁸⁶Sr) and geochemical (high Sr/Y) similarities to magmas generated at modern plate boundaries—the first time such a signature has been identified for Cambrian intrusive rocks in this sector of East Antarctica. These data demonstrate that: (1) the intrusive history of the Lambert Complex differs from that observed in the adjacent tectonic provinces exposed to the north and the south and (2) the geochemical characteristics of the most mafic of the known Cambrian intrusions are supportive of the notion that Cambrian orogenesis occurred at a plate boundary. This leads to the conclusion that the discrete tectonic provinces observed in the southern Prince Charles Mountains were likely juxtaposed as a result of Early Cambrian tectonism.  相似文献   

Along-Channel Winds in Howe Sound: Climatological Analysis and Case Studies     

Talaat Bakri  Ford Doherty 《大气与海洋》2017,55(1):12-30

This paper examines along-channel winds within Howe Sound, British Columbia, Canada, that occur from both the interior plateau out toward the coast as outflows and from the coast inland as inflows. First, the relationships between along-channel winds and pressure, temperature, and humidity are explored in Howe Sound–Cheakamus Valley. The pressure gradients between Pam Rocks and Squamish and Pam Rocks and Pemberton have the strongest correlations with outflow strength and that between Pam Rocks and Squamish has the strongest correlation with inflow strength. Outflows (inflows) have lower (higher) temperatures and dew point temperatures, except for the inflows in summer, which have lower dewpoint temperatures than the overall mean. Second, two case studies of outflow events are presented and described during the period of intensive observations prior to and during the Vancouver 2010 Winter Olympics. The January 2010 outflow event is caused by a zone of strong across-barrier mean sea level pressure gradient. The pressure gradient is formed behind an Arctic front that moved southward across Howe Sound. The February 2010 outflow event is caused by an approaching sea level low pressure centre from the Pacific that formed a northeast–southwest mean sea level pressure gradient across southern British Columbia. In the January case, the outflow layer is about 1.5?km deep, while it is shallower in the February case. Only the January outflow case exhibits hydraulic behaviour.  相似文献   

Wind effects on sub-tidal currents in Puget Sound     

Hiroshi Matsuura  Glenn A. Cannon 《Journal of Oceanography》1997,53(1):53-66

Wind effects on sub-tidal currents are studied using current meter records obtained at six moorings across the main basin of Puget Sound. High correlations between wind speeds and currents are found near the surface and at mid-depths of about 100 m. Empirical Orthogonal Function analysis applied to the axial currents in 1984 and 1985 shows that mode 1, containing over 60% of the variance, is highly correlated with wind speed even without any near surface current records. When near surface stratification is strong, direct wind effects are limited to the upper 30 m with counter currents in the lower layer indicating a baroclinic response. The transport in the lower layer almost balances the transport in the upper layer. When near surface stratification is weak, direct wind effects on currents can be detected to about 100 m. In this case, there is no clear and consistent depth at which one can separate the upper from the lower layer. Time series show that the acceleration in the surface layer initially increases in the same direction as the wind when the wind starts blowing, but it reaches a maximum, starts decreasing, and eventually changes to the opposite direction (decelerates) while the wind continues to blow in one direction. Results of a continuously stratified normal mode model and estimations from the observations suggest that friction at solid boundaries is a major cause of these phenomena. The model shows that modal currents of normal modes 2 and 3 are as important as mode 1, although the resultant vertical structure of total current shows a two-layer type pattern with only one zero crossing. The effect of the baroclinic pressure gradient is only apparent at low frequencies and among lower modes.  相似文献   

Retrospective analysis: bile hydrocarbons and histopathology of demersal rockfish in Prince William Sound,Alaska, after the Exxon Valdez oil spill     

Marty GD  Hoffmann A  Okihiro MS  Hepler K  Hanes D 《Marine environmental research》2003,56(5):569-584

Demersal rockfish are the only fish species that have been found dead in significant numbers after major oil spills, but the link between oil exposure and effect has not been well established. After the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, several species of rockfish (Sebastes spp.) from oiled and reference sites were analyzed for hydrocarbon metabolites in bile (1989-1991) and for microscopic lesions (1990 and 1991). Biliary hydrocarbons consistent with exposure to Exxon Valdez oil were elevated in 1989, but not in 1990 or 1991. Significant microscopic findings included pigmented macrophage aggregates and hepatic megalocytosis, fibrosis, and lipid accumulation. Site differences in microscopic findings were significant with respect to previous oil exposure in 1991 (P=0.038), but not in 1990. However, differences in microscopic findings were highly significant with respect to age and species in both years (P<0.001). We conclude that demersal rockfish were exposed to Exxon Valdez oil in 1989, but differences in microscopic changes in 1990 and 1991 were related more to age and species differences than to previous oil exposure.  相似文献   

Restoration of oiled mussel beds in Prince William Sound, Alaska   总被引：1，自引：0，他引：1  

Carls MG  Harris PM  Rice SD 《Marine environmental research》2004,57(5):359-376

Natural loss of hydrocarbons was often low from mussel (Mytilus trossulus) beds (which were typically not cleaned after the Exxon Valdez oil spill), thus this habitat remained a long-term source of oil. Consequently, experimental restoration of nine contaminated beds was attempted in 1994; mussels were removed, contaminated surface sediment was replaced (33 metric tons), and original mussels were returned. Hydrocarbon concentrations and mussel populations were monitored for 5 years thereafter. Post-restoration mussel population fluctuations were indistinguishable from regional changes. Increased short-term oil loss was apparent, but long-term (5 year) improvement was equivocal and difficult to distinguish from natural losses. By 1999, oil concentrations in mussels were typically at baseline levels in restored and oiled reference beds; concentrations in replaced sediment were elevated in one third of restored beds, indicating recontamination from underlying or surrounding sediment. Our results suggest mussel relocation is feasible but suggest oil might more effectively be removed from sediment mechanically or chemically than manually.  相似文献   

The Three Results of Sound Velocity Variance in Sediments During Controlled Stress-strain Testing from the South China Sea   总被引：1，自引：0，他引：1  

Bo Lu  Ganxian Li  Shaojian Huang  Shuzhuo Liu 《Marine Georesources & Geotechnology》2002,20(3):177-186

Sound velocity in each type of seafloor sediment from the South China Sea varies with the development of strain in the controlled stress-strain course. Experiments show that there may exist three cases for the maximum sound velocity: (1) it appears at the stress peak; (2) it appears in the phase of no load; and (3) it appears at the end of the strain course. These results are related to physical-mechanical properties and structure of sediments.  相似文献   

Geochemistry of granulite‐facies granitic rocks from Battye Glacier,northern Prince Charles Mountains,East Antarctica     

N. C. N. Stephenson 《Australian Journal of Earth Sciences》2013,60(1):83-94

Proterozoic basement outcrops in the vicinity of Battye Glacier, northern Prince Charles Mountains, are dominated by granulites and gneisses derived from felsic (granitoid) intrusive igneous rocks, and by pegmatites. Felsic orthopyroxene granulites, garnet leucogneisses and garnet pegmatites have major and trace element compositions of highly felsic, but not strongly fractionated, granites. The garnet leucogneisses and garnet pegmatites have S‐type characteristics, whereas the felsic granulites are probably I‐type, although their high Zr+Nb+Y+Ce abundances suggest possible A‐type affinities. Intermediate orthopyroxene ± clinopyroxene granulites mostly resemble I‐type quartz diorites, except for a small subgroup of samples (characterised by low Na₂O and K₂O, and high MgO, Ni, Cr and HREE) of uncertain affinities and significance. Element ratios involving LILE (e.g. K/Rb, Rb/Ba, Rb/Sr, K/La, La/Th) closely match those typical of the inferred granitoid protoliths, suggesting that these rocks have experienced relatively little LILE depletion (except possibly for U) during regional metamorphism. It is therefore inferred that metamorphism was probably broadly isochemical. Because the felsic and intermediate granulites and garnet leucogneisses are Sr‐depleted, Y‐undepleted and mostly have negative Eu anomalies they are inferred to be the products of partial melting of felsic crustal sources leaving plagioclase‐bearing residua. Plagioclase fractionation during crystallisation could also account for these characteristics, but K/Rb, Rb/Ba and Rb/Sr ratios in these rocks are not consistent with strong fractionation of feldspar. Garnet pegmatites differ chemically from garnet leucogneisses mainly in their lower Fe, Ti, Nb, Zn, Zr, Th and REE abundances and positive Eu anomalies, related to lower garnet, ilmenite and zircon contents in the garnet pegmatites. A genetic link between these two rock types, probably involving fractionation of these minerals during partial melting or crystallisation, is inferred. Incompatible‐element abundances suggest that generation of the Battye Glacier granitic magmas from felsic crust might have occurred in a mature continental magmatic arc possibly well removed from an active subduction trench or, perhaps, in an intracontinental setting.  相似文献   

Relocations of Earthquakes (1899–1917) in South-Central Alaska     

Diane I. Doser 《Pure and Applied Geophysics》2006,163(8):1461-1476

I have relocated 18 earthquakes occurring in the south-central Alaska region between 1899 and 1917 using a bootstrap relocation technique. Locations of events within the Yakutat region suggest that the 1899 sequence began on 4 September with a M_S = 7.9 event within the area of the Pamplona fault zone/western Transition fault zone, rupturing the western portion of the North American/Pacific plate interface. A M_S = 7.4 event on 10 September appears to have ruptured the offshore portion of the plate interface to the east of the 4 September event. This was followed by a M_S = 8.0 event that likely ruptured the onshore and down-dip portion of the plate interface. A M_S = 7.0 event in 1908 may have ruptured a small portion of the plate interface between the 4 September and 10 September events. Events occurring between 1911 and 1916 in the Prince William Sound region appear to be slab events occurring in similar locations to more recent seismicity. Within the Kodiak region the 1900 earthquake of M_S = 7.7 has a location consistent with the rupture of the Kodiak asperity which also ruptured during the 1964 great Alaska earthquake. Other large magnitude Kodiak events appear to be associated with regions of recent seismicity, including the Karluk Lake area of southwestern Kodiak Island and the Albatross Basin located offshore southeast of Kodiak Island. Space-time seismicity patterns since 1899 indicate that magnitude 6 to7 events have occurred with regularity in the Kodiak Island region; that there has been a lack of magnitude ≥ 6 events in the Prince William Sound region since 1964, and that the Yakutat region has remained notably quiescent at the magnitude ≥ 6 level.  相似文献