Spelling suggestions: "subject:"0nvironmental science."" "subject:"anvironmental science.""
211 |
Mercury and PCB residues in Massachusetts river otters: Comparisons on a watershed basisOrgan, John F 01 January 1989 (has links)
Mercury and polychlorinated biphenyl (PCB) residues in livers of trapper harvested river otters from Massachusetts were evaluated. Two-hundred and ten river otters collected during 1986 and 1987 were composited into 103 samples and analyzed. Comparisons among 20 watersheds were made using 96 samples. Mercury residues were detected in all samples and ranged from 0.45 to 4.82 ppm wet weight with an arithmetic mean of 1.93 ppm. PCB residues were detected in all but 3 samples and ranged from none-detected (ND) to 22.00 ppm with a geometric mean of 1.03 ppm wet weight. Lipid-adjusted total PCBs ranged from ND to 6.47 ppm with a geometric mean of 0.36 ppm. Significant differences (P $<$ 0.05) were detected among watersheds for mercury, total PCBs, and lipid-adjusted total PCBs. A significant difference between years was detected for lipid-adjusted total PCBs. Tukey's HSD test indicated the Charles, Blackstone, and Parker watersheds had significantly higher otter liver mercury residues than the Westfield, Quinnebaug, Deerfield, Connecticut, Buzzard's Bay, and North Coastal watersheds. Juvenile otters had significantly (P = 0.007) lower mercury residues than older otters. Tukey's HSD test indicated the Housatonic, Buzzard's Bay, Merrimack, Concord, and Charles watersheds had significantly higher otter liver total PCB residues than 13 of the remaining 15 watersheds sampled. Juvenile otters had significantly (P = 0.02) lower levels of total PCBs than older otters. Correlations between otter residues and whole-body fish residues on a watershed basis showed a strong relationship between fish and otter mercury residues. River otters can be used to assess general background mercury and PCB contamination levels on a watershed basis to prioritize and justify more intensive contaminant monitoring efforts. However, caution in interpreting PCB residue analyses is strongly recommended because of high variances associated with watershed means. River otter populations do not appear to be at risk singly from either mercury or PCB contamination in Massachusetts. Population monitoring should evaluate potential additive or synergistic effects of mercury in combination with PCBs in certain watersheds. Laboratory research is needed to document effect levels of environmental contaminants in river otters.
|
212 |
Relationship between larval habitat characteristics and malaria vectorial capacity of adult Anopheles dirus in Chanthaburi Province, ThailandKitthawee, Sangvorn 01 January 1990 (has links)
Field studies were conducted in Tha-Mai District, Chanthaburi Province. Larval habitat characteristics of 42 gem pits were examined from November 1986 through June 1988. Larvae were found in pits containing clear water under full or partial shade. Relationships between habitat characteristics and density were tested by stepwise regression analysis. High dissolved oxygen and humidity and low pH were associated with higher densities. Populations fluctuated with rainfall. Stepwise logistic regression analysis was used to predict the occurrence of An. dirus. Populations were positively correlated with humidity and collection water temperature but negatively correlated with pH and minimum water temperature. Variations in occurrence and density also were related to predators (Notonectidae and fish). High minimum water temperature and rainfall were correlated with decreases in wing length among both emerging males and females. High turbidity was associated with increased size in male but not in female. Seasonal variation in the size of both sexes was related to rainfall. Minimum water temperature, pH, protein and rainfall were correlated with the survivorship of emerging An. dirus. Adult size was positively correlated with survivorship but not as strongly as in lab-reared populations. Mean wing length of nulliparous females (3.035 mm) was not significantly smaller than parous females (3.039 mm). However, there was a significant difference when seasonal variation was considered. Since size variation was correlated with rainfall and minimum air temperature, females tended to be smaller in the rainy season and larger (with a higher parity rate) in the dry season. On average, $>$40% of dry season An. dirus live long enough to complete the extrinsic incubation period for Plasmodium falciparum. Both P. falciparum and P. vivax were detected and mosquito infection rates determined by ELISA. Malaria sporozoites were found in Anopheles dirus, vagus tessellatus and hyrcanus group so all are potential vectors in this area. Four size classes of An. dirus were reared from different larval densities. Higher densities produced smaller adults with lower survivorship. Larger females took larger blood meals and thereby were more susceptible to infection by artificial feeding with cultured P. falciparum gametocytes.
|
213 |
Socioeconomic Dimensions of Urban Greenspace Access and Usage PatternsSimon, Joshua J. January 2020 (has links)
No description available.
|
214 |
An evaluation of the importance of plant resources to rural communities - a case study of Heuningvlei in the CederbergReay, Nicky 13 February 2017 (has links)
Within the framework of living resource conservation as advocated by the world Conservation Strategy, this case study investigates the utilitarian value of indigenous plant resources as a supplementary or "hidden" income for a rural community at Heuningvlei. The objectives of the study were to document the rapidly disappearing customary knowledge regarding the utilisation of plant resources, to gain an indication of whether a sustainable method of utilisation exists within the case study community, and to interpret the results in terms of conservation objectives.
|
215 |
Evaluating the Environmental Impact of Corn Stover Collection for Biofuels ProductionKhanal, Asmita 19 December 2018 (has links)
No description available.
|
216 |
Modeling Atmospheric Transport of Perfluorinated Alkyl Substances from Chemours Facilities Using CALPUFF ViewMoreno, Anjelica Victoria Peralez 28 August 2019 (has links)
No description available.
|
217 |
Lithofacies And Paleoenvironments Of The Becraft Formation (Lower Devonian) Of New York StateArif, Abu January 1973 (has links)
The Becraft Formation from the Lower Devonian of eastern New York is a crinoid-brachiopod calcarenite which represents a combination of regressive and transgressive lithologies. Three lithofacies are recognized within the Becraft: Facies 1, a shale and biomicrite interbedded with biosparite, deposited in a transitional environment between an offshore zone of mud deposition and an above wave base shoal environment; Facies 2, a massive biosparrudite and biosparite, the prograding shoal, deposited at or above wave base; and Facies 3, a massive fine-grained biosparite, interpreted as reworked shoal sediment deposited during renewed transgression in late Becraft time. The Becraft shoal formed in the strait connecting the Helderberg and New England seas which first opened late in the Gedinnian. A new time-stratigraphy is developed for the Becraft. The turning point from a regressive to a transgressive sedimentary sequence interpreted from the distribution of gypidulids and changes in sedimentary texture is used as a time-datum for defining the new time-stratigraphic relationships. / Earth and Environmental Science
|
218 |
Genesis And Environmental Position Of The Algal Mounds Of The Stonehenge FormationManns, Francis T. January 1973 (has links)
Carbonate mounds of the Lower Ordovician (Canadian) Stonehenge Formation contain evidence of algal origin in the form of convex upward growth structures, stromatolites, and filamentous algae. Facies distribution and thickness relationships of the Stonehenge show that the mounds formed near the margins of a distinct sedimentary basin on the Cambro-Ordovician carbonate platform of Pennsylvania. Interpretations of the sedimentary environments of the major lithologies deposited in the seaway indicate that the Stonehenge beds were deposited in facies mosaic style. Five major lithologic associations have been described and interpreted in this framework. 1. dolostone cycles ... supratidal facies, 2. siliceous dolomitic pelmicrite ... subtidal flat facies, 3. intrasparudite-intrasparite ... subtidal channel facies, 4. massive calcilutite ... algal mound facies, 5. cryptalgal calcarenite ... mound debris facies. The positions of these lithologies in the stratigraphic succession of the Stonehenge indicate that the mounds formed in the base of subtidal channels at the climax of a regional transgression. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Manns-Supplemental-1973.pdf
|
219 |
Paleoenvironmental Analysis Of The Upper Silurian Callocystitidae (Cystoidea, Rhombifera) In The Central AppalachiansStephenson, David Charles January 1974 (has links)
The dominantly transgressive Upper Silurian interval of the Keyser Limestone (U. Sil. - L. Dev.) in the central Appalachians has yielded the most diverse fauna of rhombiferan cystoids found in any single formation in North America. All forms are members of the Callocystitidae, a diverse family of the Glyptocystitida. Nine lithofacies are recognized within this stratigraphic interval, representing all major epeiric sea environments from supratidal through shallow shelf below wave base. Identification of cystoid genera and species by disarticulated part studies (comparison of isolated plates to the corresponding element on whole thecae of known taxa) demonstrates their restriction to three discrete assemblages on the open shelf.
Cystoid bearing lithofacies represent a contemporaneous and laterally coexisting sequence of skeletal sands and silt which include: 1. well sorted calcarenite (both biosparudite and biosparite), 2. poorly sorted biosparite, 3. open shelf (fossiliferous) calcisiltite. Maximum cystoid diversity is recorded in the calcisiltite, diminishing progressively in coarser shoreward calcarenites. Callocystitid distribution is suggested to have been primarily depth controlled. These cystoids were intolerant of turbid water, high sedimentation rate and of high energy nearshore sands and infirm mud bottoms. A new genus Laosacystis monterey is described and assigned to the subfamily Staurocystinae on the basis of its four protuberant ambulacra. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Stephenson-Supplemental-1974.pdf
|
220 |
The Petrology Of A Triassic Diabase Intrusion Near Frederick, MarylandSutphen, Charles F. January 1975 (has links)
Excellent exposures of an 80 meter wide, 40 kilometer long vertical diabase intrusion near Frederick, Maryland, were extensively studied. This diabase has been classified as a low-TiO2 (approx. 0.80 wt. % TiO2) quartz-normative (approx. 0.9 wt. % quartz) tholeiite and correlates with the quartz-normative Triassic diabases common in northeastern United States (Weigand and Ragland, 1970) and, more specifically, the 0.80 wt. % TiO2 falls within the 0.60-0.85 wt. % range typical of the Rossville-type of Triassic diabase in Pennsylvania (Smith, 1973). The presence of centimeter-sized plagioclase (An90+5) phenocrysts and the absence of olivine and presence of quartz in the CIPW norms also indicates a correlation with the Rossville type.
The intrinsic oxygen fugacity was studied using the techniques of Buddington and Lindsley (1964) and Sato (1971). Good agreement was found between the two methods; for example, at 1100 C, the fO2 determined using both techniques was 10^-12+/-0.5 atmospheres at one atmosphere total pressure. The one atmosphere dry solidus was found to be at 1005+/-5 C and the one kbar and ten kbar wet (3 wt. % H2O) solidus were at 885+/-15 C and 800+/-15 C respectively. The one atmosphere dry liquidus was found to be at 1210+/-5 C, and the one kbar wet (3 wt. % H2O) liquidus was at 1165+/-15 C. The ten kbar wet liquidus although not within the range of the equipment used, was determined to be above 1150 C.
Using the pyrolite model of Green and Ringwood (1967), the Frederick disbase is the result of differentiation of an olivine tholeiite in a magma chamber within 25+/-5 kilometers of the surface, which was subsequently intruded near the surface during the initial stages of the opening of the Atlantic Ocean in the early Mesozoic. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Sutphen-Supplemental-1975.pdf
|
Page generated in 0.0716 seconds