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151.
Obiri S Cobbina SJ Armah FA Naangmenyele Z 《Environmental science and pollution research international》2011,18(7):1166-1173
Objective
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in street dust in the Tamale metropolis, Ghana, have been measured in this study.Results
The concentrations of the various types of PAHs identified in street dust samples from high vehicular traffic density in the metropolis are as follows: naphthalene, 10,000 μg/kg; acenaphthylene, 13,000 μg/kg; acenaphthene, 76,000 μg/kg; fluorene, 18,900 μg/kg; phenanthrene, 40,000 μg/kg; anthracene, 21,000 μg/kg; fluoranthene, 35,200 μg/kg; pyrene, 119,000 μg/kg; benzo[a]anthracene, 17,700 μg/kg; chrysene, 10,600 μg/kg; benzo[k]fluoranthene, 18,700 μg/kg; benzo[a]pyrene, 10,900 μg/kg and benzo[g, h, i]perylene, 21,000 μg/kg. Calculation of the phenanthrene/anthracene ratio indicated that the PAHs identified in this study were from vehicular fallout as the ratio was less than 10.Conclusion
It is clear from the results of the study that road users in the Tamale metropolis, especially hawkers, are exposed to the harmful effects of PAHs, and this suggests the need for the establishment of mitigation measures by the regulatory agencies.152.
Jarecki MK Parkin TB Chan AS Hatfield JL Jones R 《Journal of environmental quality》2008,37(5):1685-1690
Accurate assessment of N(2)O emission from soil requires continuous year-round and spatially extensive monitoring or the use of simulation that accurately and precisely predict N(2)O fluxes based on climatic, soil, and agricultural system input data. DAYCENT is an ecosystem model that simulates, among other processes, N(2)O emissions from soils. The purpose of the study was to compare N(2)O fluxes predicted by the DAYCENT model to measured N(2)O fluxes from an experimental corn field in central Iowa. Soil water content temperature and inorganic N, simulated by DAYCENT were compared to measured values of these variables. Field N(2)O emissions were measured using four replicated automated chambers at 6-h intervals, from day of year (DOY) 42 through DOY 254 of 2006. We observed that DAYCENT generally accurately predicted soil temperature, with the exception of winter when predicted temperatures tended to be lower than measured values. Volumetric water contents predicted by DAYCENT were generally lower than measured values during most of the experimental period. Daily N(2)O emissions simulated by DAYCENT were significantly correlated to field measured fluxes; however, time series analyses indicate that the simulated fluxes were out of phase with the measured fluxes. Cumulative N(2)O emission calculated from the simulations (3.29 kg N(2)O-N ha(-1)) was in range of the measured cumulative N(2)O emission (4.26 +/- 1.09 kg N(2)O-N ha(-1)). 相似文献
153.
The objectives of this research were to evaluate nitrate N (NO3-N) leaching and turf response to nitrogen rate (NR) and irrigation regime (IR) in 'Floratam' St. Augustinegrass ( [Walt.] Kuntze.) and 'Empire' zoysiagrass ( Steud). The research was conducted in Citra, FL, from 2005 through 2007. Nitrogen (N) was applied at annual rates of 32, 64, 128, and 196 kg ha?1 in 2005, and at 49, 196, 343, or 490 kg ha?1 in 2006 and 2007. Irrigation treatments consisted of 1.3 cm applied twice weekly or 2.6 cm applied once weekly. In general, NO?-N leaching was greater from zoysiagrass. In 2007, annual NO?-N leached varied due to the interaction of NR, IR, and grass. There was little association between NR and increased NO?-N leaching in St. Augustinegrass in any year. While St. Augustinegrass had no differences in NO?-N leached within NR due to IR, there were some differences in NO?-N leached from zoysiagrass at some N levels, with greater NO?-N leached from the more frequent irrigation regime. Turf quality (TQ) was generally above an acceptable level in St. Augustinegrass at all but the lowest NRs and at all NRs in zoysiagrass with the exception of the spring fertilizer cycle (SFC) in 2007, when high NR treatments resulted in disease. Maintenance of a healthy turfgrass cover is an important strategy for reducing potential nutrient movement from fertilizer application. The current recommended rates for St. Augustinegrass provide good turf cover and health, and result in minimal NO?-N leaching. Zoysiagrass N rates may need to be revised downward to reduce disease, improve turf cover, and reduce NO?-N leaching. 相似文献
154.
We monitored nest boxes during 1997–1999 at Acadia National Park, Mt. Desert Island, ME and at an old-field site in Orono,
ME to determine mercury (Hg) uptake in tree swallow (Tachycineta bicolor) eggs, tissues, and food boluses. Also, in 1998–1999 we monitored nest boxes at Grove Pond and Plow Shop Pond at a U.S. Environmental
Protection Agency Superfund site in Ayer, MA. We recorded breeding success at all locations. On average among locations, total
mercury (THg) biomagnified 2 to 4-fold from food to eggs and 9 to 18-fold from food to feathers. These are minimum values
because the proportion of transferable methyl mercury (MeHg) of the THg in insects varies (i.e., 35%–95% of THg) in food boluses.
THg was highest in food boluses at Aunt Betty Pond at Acadia, whereas THg in eggs was highest at the Superfund site. A few
eggs from nests at each of these locations exceeded the threshold (i.e., 800–1,000 ng/g, wet wt.) of embryotoxicity established
for Hg. Hatching success was 88.9% to 100% among locations, but five eggs failed to hatch from 4 of the 11 clutches in which
an egg exceeded this threshold. MeHg in feathers was highest in tree swallows at Aunt Betty Pond and the concentration of
THg in bodies was related to the concentration in feathers. Transfer of an average of 80%–92% of the Hg in bodies to feathers
may have enhanced nestling survival. Residues of Hg in tissues of tree swallows in the Northeast seem higher than those of
the Midwest. 相似文献
155.
Diamond J Stribling JB Stribling JR Huff L Gilliam J 《Environmental monitoring and assessment》2012,184(4):2247-2260
Many organizations in the USA collect aquatic bioassessment data using different sampling and analysis methods, most of which
have unknown performance in terms of data quality produced. Thus, the comparability of bioassessments produced by different
organizations is often unknown, ultimately affecting our ability to make comprehensive assessments on large spatial scales.
We evaluated a pilot approach for determining bioassessment performance using macroinvertebrate data obtained from several
states in the Southeastern USA. Performance measures evaluated included precision, sensitivity, and responsiveness to a human
disturbance gradient, defined in terms of a land disturbance index value for each site, combined with a value for specific
conductance, and instream habitat quality. A key finding of this study is the need to harmonize ecoregional reference conditions
among states so as to yield more comparable and consistent bioassessment results. Our approach was also capable of identifying
potential areas for refinement such as reevaluation of less precise, sensitive, or responsive metrics that may result in suboptimal
index performance. Higher performing bioassessments can yield information beyond “impaired” versus “unimpaired” condition.
Acknowledging the limitations of this pilot study, we would recommend that performance evaluations use at least 50 sites,
10 of which are ecoregional reference sites. Efforts should be made to obtain data from the entire human disturbance gradient
in an ecoregion to improve statistical confidence in performance measures. Having too few sites will result in an under-representation
of certain parts of the disturbance gradient (e.g., too few poor quality sites), which may bias sensitivity and responsiveness
estimates. 相似文献
156.
Donald E. Sorrels Douglas R. Liljedahl Jerry L. Terry 《Journal of the Air & Waste Management Association (1995)》2013,63(4):334-338
Idle emissions inspection and maintenance was evaluated using a sample of 300 privately owned 1964 through 1973 model-year vehicles operating in the Denver metropolitan area. Ten privately owned stations, licensed by the State of Colorado to perform vehicle safety inspections, were utilized to conduct idle emissions inspection and subsequent maintenance of failed vehicles. Exhaust hydrocarbon (HC) and carbon monoxide (CO) reduction as measured by the 1975 Environmental Protection Agency (EPA) mass emission testing procedures was indicated to be 13% and 8% respectively at a 50 % rejection rate. The average maintenance cost to achieve the reduction was $11.32 per failed vehicle. The adjustment and repair procedures provided to participating garages were sufficient to achieve significant emissions reduction and training provided to garage personnel was adequate. However, several problems were experienced with station personnel relative to data transmittal and inspection pass/fail limits. Problems were also experienced with respect to correlations between laboratory and garage-type analytical instrumentation. 相似文献
157.
Barbara L. Durso Joe G. Moore Jr. Jerry W. Crowder 《Journal of the Air & Waste Management Association (1995)》2013,63(4):386-387
ABSTRACT This study utilized a biotrickling filter with blast-furnace slag packings (sizes = 20-40 mm; specific surface area = 120 m2/m3) to treat toluene in an air stream. Also studied were the effects of volumetric loading (L), nutrient addition, and superficial gas velocity (Ug) or gas retention time on toluene elimination capacity. Experimental results indicate that, for a test period of 121 days, with no excess biomass removal, toluene removal efficiencies of over 90% were obtained with Ug < 80 m/hr and L < 30 g/m3.hr. For a test period of 49 days, with Ug < 80 m/hr and L increased from 1.2 to 81 g/m3.hr, the absence of nutrient supplementation did not limit the toluene elimination capacity. Nutrients stored in the biofilm could adequately support the microbial activity for the toluene elimination. According to data regression, a simplified mass-transfer model is proposed, which correlates the contaminant concentration with the packing height or gas empty bed retention time. As verified, the model proposed herein can be applied to cases involving low influent contaminant concentrations or loadings to the extent that none or only a trace amount of the contaminant can be found in the recirculation liquid. Although small media with larger specific surface areas can achieve a better mass transfer, the problems of frequent backwashing and relatively greater gas resistance in using this type of media probably outweigh the advantages, particularly for full-scale systems that would not be watched as closely as laboratory test systems. 相似文献
158.
Michael W. Hlavinka Jerry A. Bullin 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1035-1039
Air quality models must consider error in the emissions estimates as well as in the model itself. Currently, the accepted method for determining emission factors for mobile sources is through the use of the EPA model MOBILE3. In this paper, emission factor calculations from a technique based on the conservation of mass are presented from experimental data. These emission factors are then compared to MOBILE3 simulations using the experimental conditions and two different methods of obtaining the vehicle scenario. In both cases, the mass balance gave emission factors that were from 1.5 to 2.2 times those predicted by MOBILE3. Next, mass balance and MOBILE3 emission factors were used in the dispersion models CALINE3 and TXLINE in an effort to predict the observed CO concentrations. In both models, enhanced performance was observed when mass balance data were implemented. 相似文献
159.
Nina Bhola Helen Klimmek Naomi Kingston Neil D. Burgess Arnout van Soesbergen Colleen Corrigan Jerry Harrison Marcel T. J. Kok 《Conservation biology》2021,35(1):168-178
During 2021, Parties to the Convention on Biological Diversity (CBD) are expected to meet in Kunming, China, to agree on a new global biodiversity framework aimed at halting and reversing biodiversity loss, encouraging the sustainable use of biodiversity, and ensuring the equitable sharing of its benefits. As the post-2020 global biodiversity framework evolves, parties to the convention are being exposed to a range of perspectives on the conservation and sustainable use of biodiversity, relating to the future framework as a whole or to aspects of it. Area-based conservation measures are one such aspect, and there are diverse perspectives on how new targets might be framed in relation to these measures. These perspectives represent different outlooks on the relationship between human and nonhuman life on Earth. However, in most cases there is a lack of clarity on how they would be implemented in practice, the implications this would have for biodiversity and human well-being, and how they would contribute to achieving the 2050 Vision for Biodiversity of “living in harmony with nature.” We sought to clarify these issues by summarizing some of these perspectives in relation to the future of area-based biodiversity conservation. We identified these perspectives through a review of the literature and expert consultation workshops and compiled them into 4 main groups: Aichi+, ambitious area-based conservation perspectives, new conservation, and whole-earth conservation. We found that although the perspectives Aichi+ and whole earth are in some cases at odds with one another, they also have commonalities, and all perspectives have elements that can contribute to developing and implementing the post-2020 global biodiversity framework and achieving the longer term CBD 2050 Vision. 相似文献
160.
Impacts of livestock grazing in arid and semiarid environments are often concentrated in and around wetlands where animals congregate for water, cooler temperatures, and green forage. We assessed the impacts of winter-spring (November-May) cattle grazing on marsh vegetation cover and occupancy of a highly secretive marsh bird that relies on dense vegetation cover, the California Black Rail (Laterallus jamaicensis coturniculus), in the northern Sierra Nevada foothills of California, U.S.A. Using detection-nondetection data collected during repeated call playback surveys at grazed vs. ungrazed marshes and a "random changes in occupancy" parameterization of a multi-season occupancy model, we examined relationships between occupancy and habitat covariates, while accounting for imperfect detection. Marsh vegetation cover was significantly lower at grazed marshes than at ungrazed marshes during the grazing season in 2007 but not in 2008. Winter-spring grazing had little effect on Black Rail occupancy at irrigated marshes. However, at nonirrigated marshes fed by natural springs and streams, grazed sites had lower occupancy than ungrazed sites. Black Rail occupancy was positively associated with marsh area, irrigation as a water source, and summer vegetation cover, and negatively associated with marsh isolation. Residual dry matter (RDM), a commonly used metric of grazing intensity, was significantly associated with summer marsh vegetation cover at grazed sites but not spring cover. Direct monitoring of marsh vegetation cover, particularly at natural spring- or stream-fed marshes, is recommended to prevent negative impacts to rails from overgrazing. 相似文献