High Arctic sea ice conditions influence marine birds wintering in Low Arctic regions     

Laura McFarlane Tranquilla  April Hedd  Chantelle Burke  William A. Montevecchi  Paul M. Regular  Gregory J. Robertson  Leslie Ann Stapleton  Sabina I. Wilhelm  David A. Fifield  Alejandro D. Buren 《Estuarine, Coastal and Shelf Science》2010

Ocean climate change is having profound biological effects in polar regions. Such change can also have far-reaching downstream effects in sub-polar regions. This study documents an environmental relationship between High Arctic sea ice changes and mortality events of marine birds in Low Arctic coastal regions. During April 2007 and March 2009, hundreds of beached seabird carcasses and moribund seabirds were found along the east and northeast coasts of Newfoundland, Canada. These seabird “wrecks” (i.e. dead birds on beaches) coincided with a period of strong, persistent onshore winds and heavily-accumulated sea ice that blocked bays and trapped seabirds near beaches. Ninety-two percent of wreck seabirds were Thick-billed Murres (Uria lomvia). Body condition and demographic patterns of wreck murres were compared to Thick-billed Murres shot in the Newfoundland murre hunt. Average body and pectoral masses of wreck carcasses were 34% and 40% lighter (respectively) than shot murres, indicating that wreck birds had starved. The acute nature of each wreck suggested that starvation and associated hypothermia occurred within 2–3 days. In 2007, first-winter murres (77%) dominated the wreck. In 2009, there were more adults (78%), mostly females (66%). These results suggest that spatial and temporal segregation in ages and sexes can play a role in differential survival when stochastic weather conditions affect discrete areas where these groups aggregate. In wreck years, southward movement of Arctic sea ice to Low Arctic latitudes was later and blocked bays longer than in most other years. These inshore conditions corresponded with recent climate-driven changes in High Arctic ice break-up and ice extent; coupled with local weather conditions, these ice conditions appeared to be the key environmental features that precipitated the ice-associated seabird wrecks in the Low Arctic region.  相似文献   

Ground ice on Mars: Inventory,distribution, and resulting landforms     

Lisa A. Rossbacher  Sheldon Judson 《Icarus》1981,45(1):39-59

Most (～90%) of the estimated original volume of outgassed water on Mars cannot be satisfactorily accounted for by exospheric escape or storage in the atmosphere, as frost, or in the permanent north polar ice cap. The balance may be stored as ground ice in the Martian cryosphere, a zone of permanently frozen ground that is protected from the atmosphere by a debris cover. Ground ice can exist throughout the entire cryosphere, but it need not fill it. If the ground ice does fill the cryosphere, then excess water can exist in a confined aquifer. The theoretical distribution of ground ice can be tested by identification of forms on the Martian surface that may be related to the presence of subsurface ice. The observed features that are most likely to reflect ground ice are thermokarst-like pits and debris flows. Landforms with ambivalent origins include polygonally patterned ground, lobate ejecta blankets, craters with central pits, and curvilinear features. The most persuasive morphologic evidence for ground ice is thermokarst pits and debris flows; the thermokarst pits are primarily located in the volcanic regions of Tharsis and Elysium. The association of ice-related features with these volcanic areas suggests that these forms are not directly latitude dependent. Activation by orbital variations could produce periodic, multiple episodes of melting that are dependent upon latitude. The presence of ice-related features in both hemispheres and the equatorial region of Mars indicates that ground ice may be—or have been—present over the entire planet, as predicted by the cryosphere model.  相似文献   

Paleoclimate data constraints on climate sensitivity: The paleocalibration method   总被引：1，自引：0，他引：1  

Curt Covey  Lisa Cirbus Sloan  Martin I. Hoffert 《Climatic change》1996,32(2):165-184

The relationship between paleoclimates and the future climate, while not as simple as implied in the paleoanalog studies of Budyko and others, nevertheless provides sufficient constraints to broadly confirm the climate sensitivity range of theoretical models and perhaps eventually narrow the model-derived uncertainties. We use a new technique called paleocalibration to calculate the ratio of temperature response to forcing on a global mean scale for three key intervals of Earth history. By examining surface conditions reconstructed from geologic data for the Last Glacial Maximum, the middle Cretaceous and the early Eocene, we can estimate the equilibrium climate sensitivity to radiative forcing changes for different extreme climates. We find that the ratios for these three periods, within error bounds, all lie in the range obtained from general circulation models: 2–5 K global warming for doubled atmospheric carbon dioxide. Paleocalibration thus provides a data-based confirmation of theoretically calculated climate sensitivity. However, when compared with paleodata on regional scales, the models show less agreeement with data. For example, our GCM simulation of the early Eocene fails to obtain the temperature contrasts between the Equator and the Poles (and between land and ocean areas) indicated by the data, even though it agrees with the temperature data in the global average. Similar results have been reported by others for the Cretaceous and for the Last Glacial Maximum.The U.S. Government right to retain a non-exclusive royalty-free license in and to any copyright is acknowledged.  相似文献   

Diisopropanolamine Biodegradation Potential at Sour Gas Plants   总被引：1，自引：0，他引：1  

Lisa M. Gieg  E. Anne Greene  Debora L. Coy  Phillip M. Fedorak 《Ground Water Monitoring & Remediation》1998,18(3):158-173

The potential for aerobic and anaerobic biodegradation of a sour gas treatment chemical, diisopropanolamine (DIPA), was studied using contaminated aquifer materials from three sour gas treatment sites in western Canada. DIPA was found to be readily consumed under aerobic conditions at 8°C and 28°C in shake flask cultures incubated with aquifer material from each of the sites, and this removal was characterized by first-order kinetics. In addition, DIPA biodegradation was found to occur under nitrate-, Min(IV)., and Fe(III)-reducing conditions at 28°C, and in some cases at 8°C, in laboratory microcosms, DIPA loss corresponded to consumption of nitrate, and production of Mn(II) and Fe(II) in viable microcosms compared to corresponding sterile controls. A threshold DIPA concentration near 40 mg/L was observed in the anaerobic microcosms. This report provides the first evidence that DIPA is biodegraded under anaerobic conditions, and our data suggest that biodegradation may contribute to DIPA attenuation under aerobic and anaerobic conditions in aquifers contaminated with this sour gas treatment chemical.  相似文献   

用树轮密度及宽度资料重建新疆吉木萨尔县的季节降水和最高温度   总被引：18，自引：0，他引：18  

张志华  李骥  Lisa J. Graumlich  Paul R. Sheppard 《气象学报》1998,56(1):77-86

依据新疆吉木萨尔县天山云杉树木年轮宽度、最大密度和最小密度标准化年表,讨论了晚材宽度、最大密度和最小密度,与月平均最高温度和降水的响应函数基本特征,采用逐步回归方法,确定了利用晚材宽度指数、最大密度指数和最小密度指数重建该地６～９月份降水,以及利用最大密度指数和最小密度指数重建该地４～９月份平均最高温度。重建结果可靠且与实际情况较为一致。分析发现,该地区在过去１５０年中,月平均最高温度和降水有明显的阶段性变化。  相似文献   

Response of the mixed-function oxidase system to toxicant dose, food and acclimation temperature in the bluegill sunfish     

Braulio D Jimenez  Lisa S Burtis 《Marine environmental research》1988,24(1-4)

The degree of induction of hepatic mixed function oxidase (MFO) enzymes in fish is modulated by environmental conditions. This study was designed to investigate the influence of water temperature, presence or absence of food, and exposure to benzo(a]pyrene (BaP) on the inductive response of bluegill sunfish (Lepomis macrochirus). The results show an increase in 7-ethoxyresorufin O-deethylase (EROD) activity with an increase in acclimation temperature and dose. This activity appears to be associated with a very small fraction of the total cytochrome P-450 induced. Major changes were observed in the 53- and 57-kilodaltons (kDa) electrophoretic bands.  相似文献   

A comparison of RT-PCR and Northern blot analysis in quantifying metallothionein mRNA levels in killifish exposed to waterborne cadmium     

Lisa Ann Elizabeth Kaplan  Kathleen Van Cleef  Isaac Wirgin  Joseph F. Crivello 《Marine environmental research》1995,39(1-4)

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Oxidative stress in two populations of killifish (Fundulus heteroclitus) with differing contaminant exposure histories     

Lisa R. Bacanskas  Julia Whitaker  Richard T. Di Giulio   《Marine environmental research》2004,58(2-5):597

A population of killifish (Fundulus heteroclitus) inhabiting a creosote-polluted inlet of the Elizabeth River demonstrates tolerance to the acute toxic effects exerted by contaminated sediments on reference site killifish. Previous data have suggested that upregulated antioxidant defenses contribute to short-term tolerance in killifish exposed to Elizabeth River sediments. This study investigated population differences in antioxidant defenses from wild caught Elizabeth River and reference population killifish in different seasons, and after being held in the laboratory. Parameters measured in the killifish were total glutathione concentrations (GSH_T), activities of glutathione reductase (GR), glutathione peroxidase (GPx), and lipid peroxidation (LPO), all in adult hepatic tissues. The Elizabeth River population exhibited greater GSH_T, higher GPx activities, and increased LPO as compared to the reference population. Sex specific population differences were also observed in GSH_T and GPx. Both populations displayed decreased GSH_T and increased GR from early to late summer, as well as after being held in the laboratory. This study indicates that there are many factors that may contribute to differences in levels of antioxidant defenses in addition to exposure to contaminants, including reproductive status and environmental conditions.  相似文献   

Population biology of northern shortfin squid (Illex illecebrosus) in the Northwest Atlantic Ocean and initial documentation of a spawning area     

Hendrickson  Lisa C 《ICES Journal of Marine Science》2004,61(2):252-266

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Structure and Transport of the Agulhas Current and Its Temporal Variability     

Harry?L.?BrydenEmail author  Lisa?M.?Beal  Louise?M.?Duncan 《Journal of Oceanography》2005,61(3):479-492

Using a year-long moored array of current meters and well-sampled synoptic sections, we define the variability and mean structure and transport of the Agulhas current. Nineteen current meter records indicate that time scales for the temporal variability in the alongshore and offshore velocities are 10.2 and 5.4 days, respectively. Good vertical correlation exists between the alongshore or onshore velocity fluctuations, excluding the Agulhas Undercurrent. The lateral scale for the thermocline Agulhas current is about 60 km and the onshore velocity correlations are positive throughout the Agulhas Current system. Mean velocities from the array determine that the offshore edge of the Agulhas Current lies at 203 km and the penetration depth is 2200 m offshore of the Undercurrent. Hence, daily averaged velocity sections, determined by interpolation and extrapolation of current meter locations, for a 267-day period, from the surface to 2400 m depth and from the coast out to 203 km offshore encompass the main features of the Agulhas Current system. The Agulhas current is generally found close to the continental slope, within 31 km of the coast for 211 of 267 days. There are only five days when the core of the current is found offshore at 150 km. Total transport is always poleward, varying from −121 to −9 Sv, with maximum transport occurring when the core is 62 km from the coast. Average total transport for the 267 day period is −69.7 Sv; the standard deviation in daily transport values is 21.5 Sv; and the mean transport has an estimated standard error of 4.3 Sv. The Agulhas Undercurrent, which hugs the continental slope below the zero velocity isotach, has an average equatorward transport of 4.2 Sv, standard deviation of 2.9 Sv and an estimated standard error of 0.4 Sv. Transports from the moored array are in reasonable agreement with transport results from synoptic sections. Based on time series measurements at about 30° latitude in each ocean basin, the Agulhas Current is the largest western boundary current in the world ocean.  相似文献