Metabolism of perylene by monooxygenases of the skin and liver of Ambystoma tigrinum     

Robert S Anderson  Marilyn A Angel  Francis L Rose 《Marine environmental research》1988,24(1-4)

The prevalence of dermal neoplasia among neotenic tiger salamanders (Ambystoma tigrinum) collected from the Reese Air Force Base sewage lagoon far exceeded that among salamanders from nearby uncontaminated lagoons. Perylene was the predominant pglycyclic aromatic hydrocarbon contaminant in this lagoon. Perylene was shown to be a substrate for monooxygenases in skin and liver homogenates and formed DNA-binding metabolites. Perylene exposure appeared to augment subsequent perylene metabolism by dermal enzymes but it was not a strong inducer of hepatic monooxygenases. Aroclor 1254 induced benzo(a)pyrene and perylene metabolism by both skin and liver enzymes. However, perylene apparently was not activated by salamander enzymes, as suggested by its lack of in vitro mutagenicity and failure to induce tumors.  相似文献   

Seasonal methyltin and (3-dimethylsulphonio)propionate concentrations in leaf tissue of Spartina alterniflora of the Great Bay estuary (NH)     

James H. Weber  Marilyn R. Billings  Anne M. Falke 《Estuarine, Coastal and Shelf Science》1991,33(6)

Concentrations of total recoverable inorganic tin (TRISn), monomethyltin (MeSn³⁺), dimethyltin (Me₂Sn²⁺), trimethyltin (Me₃Sn⁺) and (3-dimethylsulphonio)propionate (DMSP) were determined in leaves of Spartina alterniflora from three sites in the Great Bay estuary (NH) from 8 May to 15 September 1989. Total methyltin concentration increased from 8·9 ng g⁻¹ (fresh weight) on 8 May to 472 ng g⁻¹ on 23 May, decreased to 52 ng g⁻¹ on 7 June and 16ng g⁻¹ on 20 June, and remained low until the last sample on 18 September. Statistical calculations showed that methyltin concentrations varied significantly with sampling week, but not with site. DMSP concentrations showed very different behaviour. During the same sampling period DMSP concentrations varied only from 7·5 to 26 μmol g⁻¹ (fresh weight). DMSP concentrations varied significantly for site, but not sampling week.  相似文献   

Geochemistry of eucrites: genesis of basaltic eucrites, and Hf and Ta as petrogenetic indicators for altered antarctic eucrites     

David W Mittlefehldt  Marilyn M Lindstrom 《Geochimica et cosmochimica acta》2003,67(10):1911-1934

We performed instrumental neutron activation analysis on a large suite of antarctic and nonantarctic eucrites, including unbrecciated, brecciated, and polymict eucrites and cumulate and noncumulate eucrites. We evaluate the use of Hf and Ta, two highly incompatible elements, as sensitive indicators of partial melting or fractional crystallization processes. Comparison with rare earth element (REE) data from nonantarctic and antarctic eucrites shows that Hf and Ta are unaffected by the terrestrial alteration that has modified the REE contents and patterns of some antarctic eucrites. The major host phases for Hf and Ta—zircon, baddeleyite, ilmenite, and titanite—are much less susceptible to terrestrial alteration than the phosphate hosts of REEs. The host phases for Hf and Ta are minor or trace phases, so sample heterogeneity is a serious concern for obtaining representative compositions. The trace lithophile and siderophile element contents of noncumulate eucrites do not allow for a single, simple model for the petrogenesis of the howardite-eucrite-diogenite suite. Fractional crystallization models cannot reproduce the compositional relationship between eucrites of the main group-Nuevo Laredo trend and those of the Stannern trend. Equilibrium crystallization models cannot explain the trace element diversity observed among diogenites. Partial melting models cannot explain the W variations among eucrites, unless source regions had different metal contents. We suggest that slight variations in oxygen fugacity of eucrite source regions during partial melting can explain the W variations without requiring different metal contents. This hypothesis may fail to account for eucrite Co contents, however.  相似文献   

Partition of radiotracers between suspended particles and seawater     

Yuan-Hui Li  Linda Burkhardt  Marilyn Buchholtz  Patricia O&#x;Hara  Peter H Santschi 《Geochimica et cosmochimica acta》1984,48(10):2011-2019

Distinctive uptake mechanisms of different radiotracers by red clays in seawater are elucidated from the magnitude and change of distribution coefficients (K_d) for up to 17 γ-emitting radiotracers as functions of equilibration time, suspended particle concentration and compositions of solids and seawaters. The adsorption of ionic metals onto colloids and subsequent coagulation of colloids onto larger particles are the dominant removal processes of metals in the aquatic environments of low suspended particle concentration.  相似文献   

DO CENTRAL CITIES AND SUBURBS HAVE SIMILAR DIMENSIONS OF NEED?     

Marilyn A. Brown 《The Professional geographer》1980,32(4):400-411

This paper examines the proposition that United States suburbs are gradually acquiring many of the traits and problems traditionally associated with inner cities. An analysis of direct and surrogate measures of community development need indicates that in 1970 the average central city had a greater percapita need than the average Chicago suburb. However, the dimensions of need of central cities and suburbs are quite similar. Close associations between minority race, poverty, and female-headed families exist in both central cities and suburbs, as do high residual correlations between population decline, elderly populations, and low levels of crowding.  相似文献   

Isotopic and molecular distributions of biochemicals from fresh and buried <Emphasis Type="Italic">Rhizophora mangle</Emphasis> leaves†     

Barbara?J?SmallwoodEmail author  Matthew?J?Wooller  Myrna?E?Jacobson  Marilyn?L?Fogel 《Geochemical transactions》2003,4(1):38

Rhizophora mangle L. (red mangrove) is the dominant species of mangrove in the Americas. At Twin Cays, Belize (BZ) red mangroves are present in a variety of stand structures (tall >5 m in height, transition ~2–4 m and dwarf ~1–1.5 m). These height differences are coupled with very different stable carbon and nitrogen isotopic values[1] (mean tall δ ¹³C = -28.3‰, δ ¹⁵N = 0‰; mean tall δ ¹³C = -25.3‰, δ ¹⁵N = -10‰). To determine the utility of using these distinct isotopic compositions as 'biomarkers' for paleoenvironmental reconstruction of mangrove ecosystems and nutrient availability, we investigated the distribution and isotopic (δ ¹³C and δ ¹⁵N) composition of different biochemical fractions (water soluble compounds, free lipids, acid hydrolysable compounds, individual amino acids, and the residual un-extractable compounds) in fresh and preserved red mangrove leaves from dwarf and tall trees. The distribution of biochemicals are similar in dwarf and tall red mangrove leaves, suggesting that, regardless of stand structure, red mangroves use nutrients for biosynthesis and metabolism in a similar manner. However, the δ ¹³C and δ ¹⁵N of the bulk leaf, the biochemical fractions, and seven amino acids can be used to distinguish dwarf and tall trees at Twin Cays, BZ. The data support the theory that the fractionation of carbon and nitrogen occurs prior to or during uptake in dwarf and tall red mangrove trees. Stable carbon and nitrogen isotopes could, therefore, be powerful tools for predicting levels of nutrient limitation at Twin Cays. The δ ¹³C and δ ¹⁵N of biochemical fractions within preserved leaves, reflect sedimentary cycling and nitrogen immobilization. The δ ¹⁵N of the immobilized fraction reveals the overlying stand structure at the time of leaf deposition. The isotopic composition of preserved mangrove leaves could yield significant information about changes in ecosystem dynamics, nutrient limitation and past stand structure in mangrove paleoecosystems.  相似文献   

Biological influences on modern sulfates: Textures and composition of gypsum deposits from Guerrero Negro,Baja California Sur,Mexico     

Marilyn B. Vogel  David J. Des Marais  Mary N. Parenteau  Linda L. Jahnke  Kendra A. Turk  Michael D.Y. Kubo 《Sedimentary Geology》2010,223(3-4):265-280

Gypsum (CaSO₄·2H₂O) deposits from a range of sedimentary environments at Guerrero Negro, Baja California Sur, Mexico were investigated for microscale texture and composition in order to differentiate features formed under substantial microbial influence from those for which microbial effects were relatively minor or absent. Gypsum deposits were classified according to their sedimentary environment, textures, crystal habit, brine composition and other geochemical factors. The environments studied included subaqueous sediments in anchialine pools and in solar salterns, as well as subsurface sediments of mudflats and saltpans. Gypsum that developed in the apparent absence of biofilms included crystals precipitated in the water column and subsedimentary discs that precipitated from phreatic brines. Subsedimentary gypsum developed in sabkha environments exhibited a sinuous microtexture and poikilitically enclosed detrital particles. Water column precipitates had euhedral prismatic habits and extensive penetrative twinning. Gypsum deposits influenced by biofilms included bottom nucleated crusts and gypsolites developing in anchialine pools and saltern ponds. Gypsum precipitating within benthic biofilms, and in biofilms within subaerial sediment surfaces provided compelling evidence of biological influences on crystal textures and habits. This evidence included irregular, high relief surface textures, accessory minerals (S°, Ca-carbonate, Sr/Ca-sulfate and Mg-hydroxide) and distinctive crystal habits such as equant forms and crystals having distorted prism faces.  相似文献   

Hazardous air pollutants and flooding: a comparative interurban study of environmental injustice   总被引：1，自引：0，他引：1  

Sara Grineski  Timothy W. Collins  Jayajit Chakraborty  Marilyn Montgomery 《GeoJournal》2015,80(1):145-158

  相似文献   

Characterizing the zonally asymmetric component of the SH circulation     

William R. Hobbs  Marilyn N. Raphael 《Climate Dynamics》2010,35(5):859-873

Much research concerning the Southern Hemisphere (SH) zonally asymmetric circulation has focused on the Pacific-South American mode (PSA) or the major zonal waves. However, these large-scale decompositions may mask important local variability. In this paper the month-to-month variability explained by the zonal waves 1 and 3 is examined, and an alternative representation of the SH circulation is presented based on two quasi-stationary anticyclones in the sub-Antarctic western hemisphere. These anticyclones are related to the zonal waves, but features of their variability are masked by the zonal wave decomposition; in particular, the anticyclones’ strengths are not positively covariant. They are also compared with the leading Principal Components of the SH atmosphere. We show that they capture variance independent of the Southern Annular Mode. Additionally, they explain a generally greater fraction of the variability than the PSA, and in a manner that also includes information regarding spatial variability. These results have implications for analysis of the atmospheric-forcing of western Antarctic climate.  相似文献   

Investigating Bermuda's pollution history through stable isotope analyses of modern and museum-held gorgonian corals     

David M. Baker  Thaddeus J.T. Murdoch  Inga Conti-Jerpe  Marilyn Fogel 《Marine pollution bulletin》2017,114(1):169-175

For centuries, Bermuda has been challenged with wastewater management for the protection of human and environmental health. By quantifying the δ¹⁵N of the common sea fan Gorgonia ventalina sampled from 30 sites throughout Bermuda we show that sewage-derived nitrogen is detectable on nearshore coral reefs and declines across the lagoon to the outer rim. We also sampled gorgonians from two museum collections representing a 50y time-series (1958–2008). These samples revealed an increase in δ¹⁵N of > 4.0‰ until the mid-1970s, after which δ¹⁵N values slowly declined by ~ 2.0‰. A δ¹⁵N chronology from a gorgonian skeleton exhibited a similar decline over the last 30–40 years of approximately 0.6‰. We conclude that policies have been effective in reducing sewage impacts to Bermudian reefs. However, significant sources of sewage pollution persist and are likely have a strong impact on harbor and nearshore coral communities and human health.  相似文献