Using cytochrome P450 to monitor the aquatic environment: Initial results from regional and national surveys     

Tracy K. Collier  S.Denise Connor  Bich-Thuy L. Eberhart  Bernadita F. Anulacion  Anders Goksoyr  Usha Varanasi 《Marine environmental research》1992,34(1-4)

We are currently analyzing hepatic cytochrome P4501A and associated monooxygenase activities in fish sampled in several regional and national monitoring programs, including the National Benthic Surveillance Project of NOAA's Status and Trends Program, damage assessment studies of the Exxon Valdez oil spill, and intensive surveys of specific embayments, such as Puget Sound, Washington. Thus far, apparent contaminant-related increases in the activities of cytochrome P4501A-dependent monooxygenases have been readily measured in most test species. The results presented in this paper show that, for II species of fish, there is excellent concordance between hepatic activities of aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin-O-deethylase (EROD); moreover, levels of cytochrome P4501A determined by an enzyme-linked immunosorbent assay (ELISA) are also generally concordant with results from catalytic assays. The use of both a catalytic assay and immunoquantitation is recommended, because of the additional quality assurance provided by concurrent use of an immunoquantitation technique, which is desirable in large monitoring programs.  相似文献   

Sequence stratigraphic framework for mixed aeolian,peritidal and marine environments: Insights from the Pennsylvanian subtropical record of Western Pangaea          下载免费PDF全文

Sébastien Blanchard  Christopher R. Fielding  Tracy D. Frank  James E. Barrick 《Sedimentology》2016,63(7):1929-1970

Due to difficulties in correlating aeolian deposits with coeval marine facies, sequence stratigraphic interpretations for arid coastal successions are debated and lack a unifying model. The Pennsylvanian record of northern Wyoming, USA, consisting of mixed siliciclastic–carbonate sequences deposited in arid, subtropical conditions, provides an ideal opportunity to study linkages between such environments. Detailed facies models and sequence stratigraphic frameworks were developed for the Ranchester Limestone Member (Amsden Formation) and Tensleep Formation by integrating data from 16 measured sections across the eastern side of the Bighorn Basin with new conodont biostratigraphic data. The basal Ranchester Limestone Member consists of dolomite interbedded with thin shale layers, interpreted to represent alternating deposition in shallow marine (fossiliferous dolomite) and supratidal (cherty dolomite) settings, interspersed with periods of exposure (pedogenically modified dolomites and shales). The upper Ranchester Limestone Member consists of purple shales, siltstones, dolomicrites and bimodally cross‐bedded sandstones in the northern part of the basin, interpreted as deposits of mixed siliciclastic–carbonate tidal flats. The Tensleep Formation is characterized by thick (3 to 15 m) aeolian sandstones interbedded with peritidal heteroliths and marine dolomites, indicating cycles of erg accumulation, preservation and flooding. Marine carbonates are unconformably overlain by peritidal deposits and/or aeolian sandstones interpreted as lowstand systems tract deposits. Marine transgression was often accompanied by the generation of sharp supersurfaces. Lags and peritidal heteroliths were deposited during early stages of transgression. Late transgressive systems tract fossiliferous carbonates overlie supersurfaces. Highstand systems tract deposits are lacking, either due to non‐deposition or post‐depositional erosion. The magnitude of inferred relative sea‐level fluctuations (>19 m), estimated by comparison with analogous modern settings, is similar to estimates from coeval palaeotropical records. This study demonstrates that sequence stratigraphic terminology can be extended to coastal ergs interacting with marine environments, and offers insights into the dynamics of subtropical environments.  相似文献   

Changing Intra‐Urban Location Patterns of Major League Sports Facilities     

Tracy H. Newsome  Jonathan C. Comer 《The Professional geographer》2000,52(1):105-120

The boom in U.S. major league sporting venue construction has forced many cities to face issues related to the provision of such facilities, including the location choice. Recent data show that the suburbanization trend long assumed in the literature has been reversed, with a resurgence in downtown venues. This paper demonstrates the reversal and discusses the reasons behind this recent trend. These include a concomitant trend toward smaller market franchises, increasing corporate sponsorship, deliberate downtown revitalization strategies, and the advantages accruing to owners when different parts of an urban area compete for franchises.  相似文献   

Relationship Between Oil Exposure and Reproductive Parameters in Fish Collected Following the Exxon Valdez Oil Spill     

Sean Y. Sol  Lyndal L. Johnson  Beth H. Horness  Tracy K. Collier 《Marine pollution bulletin》2000,40(12):1139-1147

Following the Exxon Valdez oil spill (EVOS) in 1989, the effect of oil exposure on reproductive parameters was investigated in wild populations of female dolly varden, yellowfin sole, and pollock. Exposure to oil was the highest in the first year of sampling and decreased in the subsequent years of sampling. Both positive and negative correlations between reproductive parameters and indices of exposure were detected in varying degrees for all three species. Reproductive parameters were not measured in the first year of sampling. For those parameters found to be significantly correlated to oil exposure, an exponential regression function was used to project reproductive parameters of fish sampled in the first year of the spill. A higher proportion of dolly varden sampled in 1989 were projected to have depressed plasma estradiol-17β compared to the fish sampled in 1990.  相似文献   

Origin of blocky aragonite cement in Cenozoic glaciomarine sediments,McMurdo Sound,Antarctica     

Mingyu Yang  Tracy D. Frank  Christopher R. Fielding  Megan E. Smith  Peter K. Swart 《Sedimentology》2020,67(2):721-741

Inorganic aragonite occurs in a wide spectrum of depositional environments and its precipitation is controlled by complex physio-chemical factors. This study investigates diagenetic conditions that led to aragonite cement precipitation in Cenozoic glaciomarine deposits of McMurdo Sound, Antarctica. A total of 42 sandstones that host intergranular cement were collected from the CIROS-1 core, located proximal to the terminus of Ferrar Glacier. Standard petrography, Raman spectroscopy and electron microprobe analysis reveal a prominent aragonite cement phase that occurs as a pore-filling blocky fabric throughout the core. Oxygen isotope compositions (δ¹⁸O = −30·0 to −8·6‰ Vienna Pee-Dee Belemnite) and clumped isotope temperatures (TΔ₄₇ = 13·1 to 31·5°C) determined from the aragonite cements provide precise constraints on isotopic compositions (δ¹⁸O_w) of the parent fluid, which mostly range from −10·8 to −7·2‰ Vienna Standard Mean Ocean Water. The fluid δ¹⁸O_w values are consistent with those of pore water, previously identified as cryogenic brine in the nearby AND-2A core. Petrographic and geochemical data suggest that aragonite cement in the CIROS-1 core precipitated from a similar brine. The brine likely formed and infiltrated sediments in flooded glacial valleys along the western margin of McMurdo Sound during the middle Miocene Climatic Transition, and subsequently flowed basinward in the subsurface. Consequently, the brine forms as a longstanding subsurface fluid that has saturated Cenozoic sediments below southern McMurdo Sound since at least the middle Miocene. Aragonite cementation in the CIROS-1 core is interpreted to reflect its proximal position to sites of brine formation and greater likelihood of experiencing brines with sustained high carbonate saturation states and Mg/Ca ratios. This unusual occurrence expands the range of known natural occurrences of aragonite cement. Given the potential for cryogenic brine formation in glaciomarine settings, blocky aragonite, as the end member of the spectrum of aragonite cement morphology, may be more widespread in glaciomarine sediments than currently thought.  相似文献   

A new flow for Canadian young hydrologists: Key scientific challenges addressed by research cultural shifts     

Caroline Aubry-Wake  Lauren D. Somers  Haley Alcock  Aspen M. Anderson  Amin Azarkhish  Samuel Bansah  Nicole M. Bell  Kelly Biagi  Mariana Castaneda-Gonzalez  Olivier Champagne  Anna Chesnokova  Devin Coone  Tasha-Leigh J. Gauthier  Uttam Ghimire  Nathan Glas  Dylan M. Hrach  Oi Yin Lai  Pierrick Lamontagne-Hallé  Nicolas R. Leroux  Laura Lyon  Sohom Mandal  Bouchra R. Nasri  Nataša Popović  Tracy E. Rankin  Kabir Rasouli  Alexis Robinson  Palash Sanyal  Nadine J. Shatilla  Brandon Van Huizen  Sophie Wilkinson  Jessica Williamson  Majid Zaremehrjardy 《水文研究》2020,34(8):2001-2006

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Ship board testing of a deoxygenation ballast water treatment   总被引：2，自引：1，他引：1  

McCollin T  Quilez-Badia G  Josefsen KD  Gill ME  Mesbahi E  Frid CL 《Marine pollution bulletin》2007,54(8):1170-1178

A ship board trial of a deoxygenation method for treating ballast water was carried out during a voyage from Southampton (United Kingdom) to Manzanillo (Panama). A nutrient solution added to two ballast tanks encouraged bacterial growth, resulting in a gradual change to an anoxic environment. Samples were taken from two treated tanks and two untreated tanks to assess changes in the abundance and viability of zooplankton, phytoplankton and bacteria. The work was carried out before the International Maritime Organization (IMO) standard was agreed so only a broad indication of whether the results achieved the standard was given. For the zooplankton, the standard would have been achieved within 5 or 7 days but the phytoplankton results were inconclusive. The biological efficacy was the result of the combination of several factors, including the treatment, pump damage and an increase in the water temperature during the voyage.  相似文献   

Pervasive aqueous paleoflow features in the Aeolis/Zephyria Plana region, Mars   总被引：1，自引：0，他引：1  

Devon M. Burr  Marie-Therese Enga  James R. Zimbelman  Tracy A. Brennand 《Icarus》2009,200(1):52-76

A survey of THEMIS visible wavelength images in the Aeolis/Zephyria Plana region over the two western lobes of the equatorial Medusae Fossae Formation (MFF) shows ∼150 sinuous ridges having a variety of morphologies and contexts. To systematize investigation, we use a classification scheme including both individual ridge and ridge network types, as well as associations with impact craters and fan-shaped features. The morphology of the ridges, their location downslope from higher topography (e.g., crater rims and scarps), and their association with fan-shaped forms indicate that most sinuous ridges formed through overland aqueous flow. Analysis of observations by individual ridge type leads to interpretation of most of these sinuous ridges as inverted fluvial channels or floodplains and a few as possible eskers, with the origin of the remaining ridges under continuing investigation. About 15% of the sinuous ridges are associated with impact craters, but data analysis does not support a genetic relationship between the craters and the sinuous ridges. Instead, analysis of one sinuous ridge network associated with a crater indicates that the water source for the network was atmospheric in origin, namely, precipitation runoff. The broad areal distribution of these ∼150 ridges and the network morphologies, in particular the branched and subparallel types, suggest that an atmospheric water source is generally applicable to the population of sinuous ridges as a whole. This concentration of sinuous ridges is the largest single population of such landforms on Mars and among the youngest. These ridges are situated at a paleoscarp between Cerberus Palus and the Aeolis highlands, suggesting that the precipitation that formed them was orographic in origin. The ages of the equatorial MFF units in which this population of sinuous ridges is found imply that this orographic rain and/or snow fell during some period from the late Hesperian through the middle Amazonian.  相似文献   

Carbonate stromatolites from a Messinian hypersaline setting in the Caltanissetta Basin, Sicily: petrographic evidence of microbial activity and related stable isotope and rare earth element signatures     

ELVIRA OLIVERI  RODOLFO NERI  ADRIANA BELLANCA  ROBERT RIDING†  Associate Editor: Tracy Frank 《Sedimentology》2010,57(1):142-161

Lower Messinian stromatolites of the Calcare di Base Formation at Sutera in Sicily record periods of low sea‐level, strong evaporation and elevated salinity, thought to be associated with the onset of the Messinian Salinity Crisis. Overlying aragonitic limestones were precipitated in normal to slightly evaporative conditions, occasionally influenced by an influx of meteoric water. Evidence of bacterial involvement in carbonate formation is recorded in three dolomite‐rich stromatolite beds in the lower portion of the section that contain low domes with irregular crinkly millimetre‐scale lamination and small fenestrae. The dominant microfabrics are: (i) peloidal and clotted dolomicrite with calcite‐filled fenestrae; (ii) dolomicrite with bacterium‐like filaments and pores partially filled by calcite or black amorphous matter; and (iii) micrite in which fenestrae alternate with dark thin wispy micrite. The filaments resemble Beggiatoa‐like sulphur bacteria. Under scanning electron microscopy, the filaments consist of spherical aggregates of dolomite, interpreted to result from calcification of bacterial microcolonies. The dolomite crystals are commonly arranged as rounded grains that appear to be incorporated or absorbed into developing crystal faces. Biofilm‐like remains occur in voids between the filaments. The dolomite consistently shows negative δ¹³C values (down to ?11·3‰) and very positive δ¹⁸O (mean value 7·9‰) that suggest formation as primary precipitate with a substantial contribution of organic CO₂. Very negative δ¹³C values (down to ?31·6‰) of early diagenetic calcite associated with the dolomite suggest contribution of CO₂ originating by anaerobic methane oxidation. The shale‐normalized rare earth element patterns of Sutera stromatolites show features similar to those in present‐day microbial mats with enrichment in light rare earth elements, and M‐type tetrad effects (enrichment around Pr coupled to a decline around Nd and a peak around Sm and Eu). Taken together, the petrography and geochemistry of the Sutera stromatolites provide diverse and compelling evidence for microbial influence on carbonate precipitation.  相似文献   

Partial melting of H6 ordinary chondrite Kernouvé: Constraints on the effects of reducing conditions on oxidized compositions     

Rena L. FORD  Gretchen K. BENEDIX  Timothy J. McCOY  Tracy RUSHMER 《Meteoritics & planetary science》2008,43(8):1399-1414

Abstract— Partial melting experiments at temperatures of 950–1300 °C were conducted on the H6 chondrite Kernouvé under reducing conditions using CO‐CO₂ gas mixing and graphite‐buffered sealed silica tubes to examine the effect of reducing conditions during melting of starting materials that are more oxidized relative to the oxygen fugacity conditions of the experiments. The experiments produced a range of mineralogical and compositional changes. Olivine exhibits significant reduction to compositions of Fa_2–5 at temperatures of 1300 °C. In contrast, orthopyroxene exhibits only slight reduction until the highest temperatures. Chromite is sometimes consumed by intruding sulfides, and displays increasingly magnesian compositions ranging as low as Fe/Fe + Mg of 0.1 at a constant Cr/Cr + Al ratio. The compositional changes with increasing temperature reflect a complex set of reactions, including oxidation‐reduction. One application of these experiments address whether primitive achondrites could have formed from ordinary chondrite‐like precursors by partial melting under reducing conditions. While changes observed in olivine and troilite compositions might support such an idea, differences in oxygen isotopic composition, Cr/Cr + Al in chromite, orthopyroxene compositions, and thermodynamic evidence against reduction during melting of primitive achondrites (Benedix et al. 2005) firmly refute such an idea.  相似文献