The Effects Of Tides And Waves On Water-Table Elevations In Coastal Zones   总被引：3，自引：1，他引：3  

Ian L. Turner  Bruce P. Coates  R. Ian Acworth 《Hydrogeology Journal》1996,4(2):51-69

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Polychlorinated biphenyl contamination in selected estuarine and coastal marine finfish and shellfish of New Jersey     

Michael J. Kennish  Bruce E. Ruppel 《Estuaries and Coasts》1996,19(2):288-295

Analysis of polychlorinated biphenyls (PCBs) in selected finfish and shellfish from the estuarine and coastal marine waters of New Jersey reveals variable levels of contamination in different regions of the state. Monitoring surveys conducted by the New Jersey Department of Environmental Protection during the last two decades indicate that biota from the northeast region are the most severely contaminated with PCBs. Early monitoring in the 1970s showed that as much as 75% of the finfish and 50% of the shellfish analyzed for Aroclor 1254—the most persistent and toxic mixture of PCBs—contained detectable levels of PCB in their edible flesh. The American eel (Anguilla rostrata), bluefish (Pomatomus saltatrix), striped bass (Morone saxatilis), white catfish (Ictalurus catus), white perch (M. americana), and blue crab (Callinectes sapidus) exhibited high PCB levels in 1981–1982, generally approaching or exceeding the United States Food and Drug Administration action level of 2 ppm fresh weight for these organisms. PCB contamination in finfish and shellfish collected during survey periods of 1986–1987 and 1988–1991 was consistent with the previous years' data showing the northeast region of the state to be the most severely contaminated. Despite decreases in contaminant levels in some species (e.g., striped bass) and regions, results of the most recent survey confirm widespread occurrences of PCBs above background levels in the edible portions of various species from many areas of New Jersey.  相似文献   

Exchange of polychlorinated biphenyls between sediment and water in the Hudson River estuary   总被引：2，自引：0，他引：2  

Diane R. Achman  Bruce J. Brownawell  Lianchu Zhang 《Estuaries and Coasts》1996,19(4):950-965

Sediment-bound polychlorinated biphenyls (PCBs) measured at several sites in the lower Hudson River Estuary are above equilibrium with the overlying water, providing a thermodynamic driving force for exchange from sediment to water. The fluxes of PCB congeners are estimated for a number potential processes: diffusive release of dissolved and colloidal PCBs from the bed, resuspension and subsequent desorption from resuspended particles, and sediment accumulation and burial. All processes are potentially significant, at least for some congeners. The sediment exchange fluxes of PCB solutes for five sites between Governors Island and Haverstraw Bay are estimated to be 20–860 μm m^?2 d^?1, which is between 2 and 100 times more than the flux of dissolved PCBs coming down the river at Haverstraw Bay. Much of the exchange from sediment to water may be balanced by burial of sorbed PCBs by sediment accumulation. Advection down the river and sediment exchange dominate other potential sources of PCBs to the lower estuary under current loading conditions. The magnitude of the calculated fluxes is consistent with the nonconservative behavior of PCBs in the same region but is higher than earlier modeling estimates that employed different assumptions.  相似文献   

Chemical contaminant exposure and effects in four fish species from Tampa Bay,Florida     

Bruce B. McCain  Donald W. Brown  Tom Hom  Mark S. Myers  Susan M. Pierce  Tracy K. Collier  John E. Stein  Sin-Lam Chan  Usha Varanasi 《Estuaries and Coasts》1996,19(1):86-104

Concentrations of selected anthropogenic chemical contaminants and levels of pollution-related biological effects were measured during three consecutive years (1990–1992) in hardhead catfish (Arius felis), Gulf killifish (Fundulus grandis), longnose killifish (F. majalis), and red drum (Scieaenops ocellatus) from 12 subtidal and intertidal sites in Tampa Bay and nearby Sarasota Bay. Each species was collected from at least four sites. Compared to nonindustrialized sites, concentrations of PCBs, DDTs, and alpha-chlordane in liver, and of fluorescent aromatic compounds in bile, were highest in fish from sites in or near Hillsborough Bay, the most industrialized portion of Tampa Bay. The results of analyses for two biochemical markers of contaminant-induced effects in fish, hepatic cytochrome P4501A activities and levels of hepatic DNA adducts, also showed the highest levels to be in all four fish species from sites in the vicinity of Hillsborough Bay. Liver lesions, considered to be pollution-associated in several other bottom-feeding fish species, were found in hardhead catfish and longnose killifish, exclusively from sites in Hillsborough Bay. Overall, concentrations of selected contaminants and their derivatives in the four target fish species generally reflected concentrations of these contaminants found in sediment. The biochemical and histopathological responses demonstrated that chemical contaminant concentrations in the vicinity of Hillsborough Bay are sufficiently high to cause adverse effects in indigenous fish species. The results, collectively, showed that the extent of contaminant exposure and biological effects in fish from sites in Tampa Bay were low to moderate compared to more urbanized coastal sites of the United States. *** DIRECT SUPPORT *** A01BY073 00009  相似文献   

C On the Velocity and Magnetic Fields At the Top of the Core     

Bruce A. Buffett 《Geophysical Journal International》1996,125(1):303-317

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Estimation of Direct Runoff in the Thornthwaite Water Balance*     

Bruce K. Ferguson 《The Professional geographer》1996,48(3):263-271

Inclusion of direct runoff in water balance analysis makes the analysis more accurate and allows it to reflect important hydrologic effects of land use change such as urbanization. Water balance analysis is conveniently performed on a monthly basis. This paper reports the development of a model of monthly direct runoff consistent with the monthly bookkeeping format. The model was evaluated by comparison with direct runoff estimated by daily calculation using the Soil Conservation Service (SCS) method. The comparison employed six stations representing different climatic regions of the contiguous United States and eight values of SCS curve number. The results are statistically significant and produce little error.  相似文献   

Surficial Geologic Surveys of Gale Crater and Melas Chasma, Mars: Integration of Remote-Sensing Data     

Shannon M. Pelkey  Bruce M. Jakosky 《Icarus》2002,160(2):228-257

Remote-sensing observations of Gale Crater and Melas Chasma are synthesized to better understand the present surface layer in these two scientifically interesting regions. Data sets analyzed include geologic maps, Mars Orbiter Laser Altimeter (MOLA) elevation, Thermal Emission Spectrometer (TES) albedo, TES thermal inertia, MOLA residual pulse width, TES rock abundance, and Viking and Mars Orbiter Camera images. Using these data sets, we constrain the properties of and processes acting on the present surface and create self-consistent models for the surface layer. Surface properties within Gale Crater are variable and complex, and interpreting the surface layer is not straightforward. Observations indicate that aeolian processes have shaped some of the intracrater surface, but other areas do not comply with this model and have counterintuitive surface characteristics. In contrast, aeolian activity appears to have played a large role in shaping the present-day physical structure of all surfaces in Melas Chasma and is reflected in the remote-sensing data sets. Here we summarize our analysis and discuss the surface attributes as determined from these data sets.  相似文献   

Photochemistry of a Volcanically Driven Atmosphere on Io: Sulfur and Oxygen Species from a Pele-Type Eruption     

Julianne I. MosesMikhail Yu. Zolotov  Bruce Fegley Jr. 《Icarus》2002,156(1):76-106

To determine how active volcanism might affect the standard picture of sulfur dioxide photochemistry on Io, we have developed a one-dimensional atmospheric model in which a variety of sulfur-, oxygen-, sodium-, potassium-, and chlorine-bearing volatiles are volcanically outgassed at Io's surface and then evolve due to photolysis, chemical kinetics, and diffusion. Thermochemical equilibrium calculations in combination with recent observations of gases in the Pele plume are used to help constrain the composition and physical properties of the exsolved volcanic vapors. Both thermochemical equilibrium calculations (Zolotov and Fegley 1999, Icarus141, 40-52) and the Pele plume observations of Spencer et al. (2000; Science288, 1208-1210) suggest that S₂ may be a common gas emitted in volcanic eruptions on Io. If so, our photochemical models indicate that the composition of Io's atmosphere could differ significantly from the case of an atmosphere in equilibrium with SO₂ frost. The major differences as they relate to oxygen and sulfur species are an increased abundance of S, S₂, S₃, S₄, SO, and S₂O and a decreased abundance of O and O₂ in the Pele-type volcanic models as compared with frost sublimation models. The high observed SO/SO₂ ratio on Io might reflect the importance of a contribution from volcanic SO rather than indicate low eddy diffusion coefficients in Io's atmosphere or low SO “sticking” probabilities at Io's surface; in that case, the SO/SO₂ ratio could be temporally and/or spatially variable as volcanic activity fluctuates. Many of the interesting volcanic species (e.g., S₂, S₃, S₄, and S₂O) are short lived and will be rapidly destroyed once the volcanic plumes shut off; condensation of these species near the source vent is also likely. The diffuse red deposits associated with active volcanic centers on Io may be caused by S₄ radicals that are created and temporarily preserved when sulfur vapor (predominantly S₂) condenses around the volcanic vent. Condensation of SO across the surface and, in particular, in the polar regions might also affect the surface spectral properties. We predict that the S/O ratio in the torus and neutral clouds might be correlated with volcanic activity—during periods when volcanic outgassing of S₂ (or other molecular sulfur vapors) is prevalent, we would expect the escape of sulfur to be enhanced relative to that of oxygen, and the S/O ratio in the torus and neutral clouds could be correspondingly increased.  相似文献   

Theoretical and numerical analyses of pore-fluid flow focused heat transfer around geological faults and large cracks     

Chongbin Zhao  Bruce E. Hobbs  Alison Ord  Peter Hornby  Hans Mühlhaus  Shenglin Peng 《Computers and Geotechnics》2008,35(3):357-371

In this paper, theoretical and numerical methods are used to investigate pore-fluid flow focused temperature distribution patterns around geological faults and cracks of any length-scales in hydrothermal systems. If the far field inflow is uniform and the long axis of an elliptical fault of any length-scale is parallel to the far field inflow direction, a complete set of analytical solutions has been presented for the pore-fluid velocity, stream function and excess pore-fluid pressure around the elliptical fault embedded in fluid-saturated porous media. Because the analytical solutions are explicitly expressed in the conventional Cartesian coordinate system, not only can they be used to gain a theoretical insight into the pore-fluid flow patterns around geological faults and large cracks, but also they can be used as valuable benchmark solutions for validating any numerical methods. After a finite element computational model is validated by comparing the numerical solutions with the present analytical solutions, it is used to investigate pore-fluid flow focused heat transfer around geological faults in hydrothermal systems. Some interesting conclusions in relation to the effects of geological faults on pore-fluid flow focused heat transfer have been made through both the theoretical and the numerical analyses.  相似文献   

Jurassic climates     

Bruce W. Sellwood 《Proceedings of the Geologists' Association. Geologists' Association》2008,119(1):5-17

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