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101.
Ralf M. Staebler Sean M. McGinn Brian P. Crenna Thomas K. Flesch Katherine L. Hayden Shao-Meng Li 《Atmospheric environment (Oxford, England : 1994)》2009,43(38):6091-6099
In Canada approximately 45% of ammonia (NH3) emissions are attributed to dairy and beef cattle industries. The present study focused on NH3 emissions from a beef feedlot with a one-time capacity of 17,220 head. The aim was to improve the Canadian NH3 emission inventories and air quality forecasting capabilities. A Cessna 207, equipped with a fast-response NH3/NOy detector and a quadrupole aerosol mass spectrometer, was flown in a grid pattern covering an area of 8 × 8 km centered on a feedlot (800 × 800 m) at altitudes ranging from 30 to 300 m above ground. Stationary ground measurements of NH3 concentration and turbulence parameters were made downwind of the feedlot. Three flights were conducted under varying meteorological conditions, ranging from very calm to windy with near-neutral stratification. NH3 mixing ratios up to 100 ppbv were recorded on the calm day, up to 300 m above ground. An average feedlot NH3 emission rate of 76 ± 4 μg m?2 s?1 (equivalent to 10.2 g head?1 h?1) was estimated. Characteristics of the measured NH3 plume were compared to those predicted by a Lagrangian dispersion model. The spatially integrated pattern of NH3 concentrations predicted and measured agreed but the measured was often more complex than the predicted spatial distribution. The study suggests that the export of NH3 through advection accounted for about 90% of the emissions from the feedlot, chemical transformation was insignificant, and dry deposition accounted for the remaining 10%. 相似文献
102.
Andrea M. Dietrich Daniel L. Gallagher Kathryn A. Klawiter 《Journal of the American Water Resources Association》2001,37(2):281-293
ABSTRACT: Inputs of copper‐based crop protectants from tomato fields grown under plastic mulch agriculture (plasticulture) to an estuarine creek were investigated. Copper was measured in runoff from diverse land‐uses including conventional agriculture, plasticulture, residences, and natural areas. Water column and sediment copper concentrations were measured in plasticulture and control (nonagriculture) watersheds. Copper concentrations in plasticulture‐impacted creeks exceeded background levels episodically. High concentrations occurred during or immediately after runoff‐producing rains. Concentrations of 263 μg/L total copper and 126 μg/L dissolved copper were measured in a tidal creek affected by plasticulture; concentrations exceeded the shellfish LC50 values and the water quality criteria of 2.9 μg/L dissolved copper. Control watersheds indicated background water column levels of ≤ 4 μg/L dissolved copper with similar copper levels during periods with and without rain. The copper concentrations in tomato plasticulture field runoff itself contained up to 238 μg/L dissolved copper. Copper concentrations in runoff from other land‐uses were less than 5 μg/L dissolved copper. Creek sediment samples adjacent to a plasticulture field contained significantly higher copper concentrations than sediments taken from nonplasticulture watersheds. 相似文献
103.
Australia has an extensive coastline extending over 60,000 km through diverse tropical and temperate environments. Indigenous
archaeological sites are found along this coastline from the time of earliest settlement at least 50,000 years ago. However,
Pleistocene sites are rare owing largely to the destructive impacts of sea-level change associated with the end of the last
ice age around 10,000 years ago. After this sites are more numerous but there is variability around the coastline due to the
impact of a range of both natural and human factors. Here we focus on six key issues impacting on the development and conservation
of coastal archaeological deposits: sea-levels, climate change, cyclones, storms, tsunamis and contemporary human impacts.
A number of examples of these impacts are discussed from across Australia. Managing and monitoring of sites has been limited
in Australia and geoindicators are discussed as a means of developing a long-term measurement of continuing impacts. 相似文献
104.
Xueshu Li Sean Parkin Michael W. Duffel Larry W. Robertson Hans-Joachim Lehmler 《Environment international》2010,36(8):843-848
Polychlorinated biphenyls (PCBs), a major class of persistent organic pollutants, are metabolized to hydroxylated PCBs. Several hydroxylated PCBs are substrates of cytosolic phase II enzymes, such as phenol and hydroxysteroid (alcohol) sulfotransferases; however, the corresponding sulfation products have not been isolated and characterized. Here we describe a straightforward synthesis of a series of ten PCB sulfate monoesters from the corresponding hydroxylated PCBs. The hydroxylated PCBs were synthesized by coupling chlorinated benzene boronic acids with appropriate brominated (chloro-)anisoles, followed by demethylation with boron tribromide. The hydroxylated PCBs were sulfated with 2,2,2-trichloroethyl chlorosulfate using DMAP as base. Deprotection with zinc powder/ammonium formate yielded the ammonium salts of the desired PCB sulfate monoesters in good yields when the sulfated phenyl ring contained no or one chlorine substituent. However, no PCB sulfate monoesters were isolated when two chlorines were present ortho to the sulfated hydroxyl group. To aid with future quantitative structure activity relationship studies, the structures of two 2,2,2-trichloroethyl-protected PCB sulfates were verified by X-ray diffraction. 相似文献
105.
An investigation was conducted regarding the potential economic benefits associated with using a wind turbine to power a groundwater circulation well (GCW) at the former Nebraska Ordnance Plant Superfund site. The first phase of the investigation used a 10‐kilowatt‐rated grid inter‐tie wind turbine to partially offset the purchase of electricity from the utility company. The second phase consisted of the conversion of the grid inter‐tie system to an off‐grid system that stored energy using batteries. During the second phase, the GCW system was operated using either wind turbine power or utility power, and the other system components were operated using utility power. The study showed that a significant amount of power purchased from the utility company was used for nonessential purposes (other than operating the GCW pump and essential treatment components). One nonessential power consumer was the continuous heating of the equipment shelter for operator comfort during their 10‐minute visit every few days. Wind‐turbine reduction in utility power consumption was evaluated, and the operating time of a hypothetical system powered solely by the wind turbine was compared to the actual GCW operating time. This study indicates that retrofitting this GCW system did not economically offset power costs from a cheap, readily available grid system. Perhaps at a remote location with a more energy‐efficient design and operation and the inclusion of green power benefits (in some monetary amount), the wind turbine results will be more favorable. The study of a renewable energy application at the site highlighted opportunities for significant electrical energy savings regardless of the source of the electricity. © 2008 Wiley Periodicals, Inc. 相似文献
106.
107.
An approach for delineating high anomaly density areas within a mixture of two or more spatial Poisson fields based on limited sample data collected along strip transects was developed. All sampled anomalies were transformed to anomaly count data and indicator kriging was used to estimate the probability of exceeding a threshold value derived from the cdf of the background homogeneous Poisson field. The threshold value was determined so that the delineation of high-density areas was optimized. Additionally, a low-pass filter was applied to the transect data to enhance such segmentation. Example calculations were completed using a controlled military model site, in which accurate delineation of clusters of unexploded ordnance (UXO) was required for site cleanup. 相似文献
108.
Tara K. Watson Dorothy Q. Kellogg Kelly Addy Arthur J. Gold Mark H. Stolt Sean W. Donohue Peter M. Groffman 《Journal of the American Water Resources Association》2010,46(2):237-245
Watson, Tara K., Dorothy Q. Kellogg, Kelly Addy, Arthur J. Gold, Mark H. Stolt, Sean W. Donohue, and Peter M. Groffman, 2010. Groundwater Denitrification Capacity of Riparian Zones in Suburban and Agricultural Watersheds. Journal of the American Water Resources Association (JAWRA) 46(2):237-245. DOI: 10.1111/j.1752-1688.2010.00418.x Abstract: We evaluated the relationship of dominant watershed land use to the structure and nitrogen (N) sink function of riparian zones. We focused on groundwater denitrification capacity, water table dynamics, and the presence and pattern of organically enriched deposits. We used the push-pull method (measurement of 15N-enriched denitrification gases derived from an introduced groundwater plume of 15N-enriched nitrate) to evaluate groundwater denitrification capacity on nine forested wetland riparian sites developed in alluvial or outwash parent materials in southern New England. Three replicate sites were located in each of the three watershed types, those with substantial (1) irrigated agriculture, (2) suburban development, and (3) forest. Soil morphology and water table dynamics were assessed at each site. We found significantly lower mean annual water tables at sites within watersheds with substantial irrigated agriculture or suburban development than forested watersheds. Water table dynamics were more variable at sites within suburban watersheds, especially during the summer. Groundwater denitrification capacity was significantly greater at sites within forested watersheds than in watersheds with substantial irrigated agriculture. Because of the high degree of variability observed in riparian sites within suburban watersheds, groundwater denitrification capacity was not significantly different from either forested or agricultural watersheds. The highly variable patterns of organically enriched deposits and water tables at sites within suburban watersheds suggests that depositional events are irregular, limiting the predictability of groundwater N dynamics in these riparian zones. The variability of riparian N removal in watersheds with extensive suburbia or irrigated agriculture argues for N management strategies emphasizing effective N source controls in these settings. 相似文献
109.
Heather M. Whitney Georgina Milne Sean A. Rands Silvia Vignolini Cathie Martin Beverley J. Glover 《Die Naturwissenschaften》2013,100(3):249-256
Patterns of pigmentation overlying the petal vasculature are common in flowering plants and have been postulated to play a role in pollinator attraction. Previous studies report that such venation patterning is significantly more attractive to bee foragers in the field than ivory or white flowers without veins. To dissect the ways in which venation patterning of pigment can influence bumblebee behaviour, we investigated the response of flower-naïve individuals of Bombus terrestris to veined, ivory and red near-isogenic lines of Antirrhinum majus. We find that red venation shifts flower colour slightly, although the ivory background is the dominant colour. Bees were readily able to discriminate between ivory and veined flowers under differential conditioning but showed no innate preference when presented with a free choice of rewarding ivory and veined flowers. In contrast, both ivory and veined flowers were selected significantly more often than were red flowers. We conclude that advantages conferred by venation patterning might stem from bees learning of their use as nectar guides, rather than from any innate preference for striped flowers. 相似文献
110.