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281.
Pig farms are a vital component of rural economies in Australia. However, disposal of effluent leads to many environmental problems. This case study of the Berrybank Farm piggery waste management system in Victoria estimates greenhouse gas (GHG) benefits from three different activities. Analysis reveals that the capturing and combusting of methane from piggery effluent could save between 4859 and 5840 tCO2e yr(-1) of GHG emissions. Similarly, using methane for replacing fuels for electricity generation could save another 800 tCO2e yr(-1)of GHGs. Likewise, by utilizing the biogas wastes to replace inorganic fertilizers there could be a further saving of 1193 to 1375 tCO2e yr(-1) of GHG, depending on the type of fertilizers the waste replaces. Therefore, a well-managed piggery farm with 15,000 pigs could save 6,852 to 8,015 tCO2e yr(-1), which equates to the carbon sequestrated from 6,800 to 8,000 spotted gum trees (age=35 year) in their above plus below-ground biomass. Implementation of similar project in suitable areas in Australia could have significant environmental and financial benefits.  相似文献   
282.
The purpose of this study was to evaluate the effect of traffic volume on ambient black carbon (BC) concentration in an inner-city neighborhood "hot spot" while accounting for modifying effects of weather and time. Continuous monitoring was conducted for 12 months at the Baltimore Traffic Study site surrounded by major urban streets that together carry over 150,000 vehicles per day. Outdoor BC concentration was measured with an Aethalometer; vehicles were counted pneumatically on two nearby streets. Meteorological data were also obtained. Missing data were imputed and all data were normalized to a 5-min observational interval (n = 105,120). Time-series modeling accounted for autoregressively (AR) correlated errors. This study found that outdoor BC was positively correlated at a statistically significant level with neighborhood-level vehicle counts, which contributed at a rate of 66 +/- 10 (SE) ng/m3 per 100 vehicles every 5 min. Winds from the SW-S-SE quarter were associated with the greatest increases in BC (376-612 ng/m3). These winds would have entrained BC from Baltimore's densely trafficked central business district, as well as a nearby interstate highway. The strong influence of wind direction implicates atmospheric transport processes in determining BC exposure. Dew point, mixing height, wind speed, season, and workday were also statistically significant predictors. Background exposure to BC was estimated to be 905 ng/m3. The optimal, statistically significant representation of BC's autocorrelation was AR([1:6]) x 288 x 2016, where the short-term AR factor (lags 1-6) indicated that BC concentrations are correlated for up to 30 min, and the AR factors for lags 288 and 2016 indicate longer-term autocorrelations at diurnal and weekly cycles, respectively. It was concluded that local exposure to BC from mobile sources is substantially modified by meteorological and temporal conditions, including atmospheric transport processes. BC concentration also demonstrates statistically significant autocorrelation at several time scales.  相似文献   
283.
The Canoparmelia texana epiphytic lichenized fungi was used to monitor atmospheric pollution in the S?o Paulo metropolitan region, SP, Brazil. The cluster analysis applied to the element concentration values confirmed the site groups of different levels of pollution due to industrial and vehicular emissions. In the distribution maps of element concentrations, higher concentrations of Ba and Mn were observed in the vicinity of industries and of a petrochemical complex. The highest concentration of Co found in lichens from the S?o Miguel Paulista site is due to the emissions from a metallurgical processing plant that produces this element. For Br and Zn, the highest concentrations could be associated both to vehicular and industrial emissions. Exploratory analyses revealed that the accumulation of toxic elements in C. texana may be of use in evaluating the human risk of cardiopulmonary mortality due to prolonged exposure to ambient levels of air pollution.  相似文献   
284.
The effects of ozone and other photochemical oxidants on individual trees have been studied for several decades, but there has been much less research on the potential effects on entire forest ecosystems. Given that ozone and other oxidants affect the production and subsequent fate of biogenic volatile organic compounds that act as signalling molecules, there is a need for more detailed study of the role of oxidants in modifying trophic interactions in forests. Deposition of fine particulates to forests may act as a source of nutrients, but also changes leaf surface properties, increasing the duration of surface wetness and modifying the habitat for epiphytic organisms, leading to increased risks from pathogens. Even where this pathway contributes a relatively small input of nutrients to forests, the indirect effects on canopy processes and subsequent deposition to the forest floor in throughfall and litter may play a more important role that has yet to be fully investigated.  相似文献   
285.
Geochemical and geostatistical study of the chromium concentration in groundwater occurring at variable depths of 12 to 33.5 m (40 to 110 ft) in the Karachi urban area of Pakistan have been made. Samples were collected at variable distances, with a maximum of 1 km interval, on the bases of population, industries, types, and density. The chromium concentration has also been worked out to deduce the threshold value of the area under study and the estimation of probability impact modeling, in terms of concentration variation, by using the disjunctive kriging technique. The outcome of the present work appears to be a good tool to decipher pollution variation in the groundwater of highly urbanized areas, with respect to the population and industries. The patterns of distribution of chromium concentration in groundwater and pollution hotspots in particular localities appear to be more related to the types of industries than to the effect of population types.  相似文献   
286.
Strontium-90 has migrated deep into the unsaturated subsurface beneath leaking storage tanks in the Waste Management Areas (WMA) at the U.S. Department of Energy's (DOE) Hanford Reservation. Faster than expected transport of contaminants in the vadose zone is typically attributed to either physical hydrologic processes such as development of preferential flow pathways, or to geochemical processes such as the formation of stable, anionic complexes with organic chelates, e.g., ethylenediaminetetraacetic acid (EDTA). The goal of this paper is to determine whether hydrological processes in the Hanford sediments can influence the geochemistry of the system and hence control transport of Sr(2+) and SrEDTA(2-). The study used batch isotherms, saturated packed column experiments, and an unsaturated transport experiment in an undisturbed core. Isotherms and repacked column experiments suggested that the SrEDTA(2-) complex was unstable in the presence of Hanford sediments, resulting in dissociation and transport of Sr(2+) as a divalent cation. A decrease in sorption with increasing solid:solution ratio for Sr(2+) and SrEDTA(2-) suggested mineral dissolution resulted in competition for sorption sites and the formation of stable aqueous complexes. This was confirmed by detection of MgEDTA(2-), MnEDTA(2-), PbEDTA(2-), and unidentified Sr and Ca complexes. Displacement of Sr(2+) through a partially-saturated undisturbed core resulted in less retardation and more irreversible sorption than was observed in the saturated repacked columns, and model results suggested a significant reservoir (49%) of immobile water was present during transport through the heterogeneous layered sediments. The undisturbed core was subsequently disassembled along distinct bedding planes and subjected to sequential extractions. Strontium was unequally distributed between carbonates (49%), ion exchange sites (37%), and the oxide (14%) fraction. An inverse relationship between mass wetness and Sr suggested that sandy sediments of low water content constituted the immobile flow regime. Our results suggested that the sequestration of Sr(2+) in partially-saturated, heterogeneous sediments was most likely due to the formation of immobile water in drier regions having low hydraulic conductivities.  相似文献   
287.
International trade in meat: the tip of the pork chop   总被引:4,自引:0,他引:4  
This paper provides an original account of global land, water, and nitrogen use in support of industrialized livestock production and trade, with emphasis on two of the fastest-growing sectors, pork and poultry. Our analysis focuses on trade in feed and animal products, using a new model that calculates the amount of "virtual" nitrogen, water, and land used in production but not embedded in the product. We show how key meat-importing countries, such as Japan, benefit from "virtual" trade in land, water, and nitrogen, and how key meat-exporting countries, such as Brazil, provide these resources without accounting for their true environmental cost. Results show that Japan's pig and chicken meat imports embody the virtual equivalent of 50% of Japan's total arable land, and half of Japan's virtual nitrogen total is lost in the US. Trade links with China are responsible for 15% of the virtual nitrogen left behind in Brazil due to feed and meat exports, and 20% of Brazil's area is used to grow soybean exports. The complexity of trade in meat, feed, water, and nitrogen is illustrated by the dual roles of the US and The Netherlands as both importers and exporters of meat. Mitigation of environmental damage from industrialized livestock production and trade depends on a combination of direct-pricing strategies, regulatory approaches, and use of best management practices. Our analysis indicates that increased water- and nitrogen-use efficiency and land conservation resulting from these measures could significantly reduce resource costs.  相似文献   
288.
To assess the effect of coumaphos [O-(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl) O,O-diethyl phosphorothioate] exposure on physiological responses during bovine production, acetylcolinesterase (AChE) and butyrylcholinesterase (BuChE) activities were measured in whole blood, erythrocytes, and plasma of healthy male steers (Bos Taurus x Bos indicus) sprayed with coumaphos at a non-lethal dose of 1 mg kg(- 1) body weight per day once every 14 (in vivo group) or 21 days (southern and central groups). Coumaphos topically administered at 1 mg/kg body weight per day to cattle under normal management practices in tropical areas produced a significant inhibition in erythrocyte (RBC) AChE and BuAChE activities when compared to baseline levels. RBC-AChE activity for the in vivo group decreased 71.3% (P < 0.05) and BuChE activity 59.1% (P < 0.05); RBC-AChE activity decreased 55.1% (P < 0.05) (southern group) and 43.4% (P < 0.05) (central group). Compared to the control specimens, steers from in vivo, southern, and central groups after 150 days of exposure had lower (P < 0.05) leukocyte count, absolute lymphocyte, erythrocyte, and platelet counts. Decreases in RBC-AChE activities correlated with decreased lymphocyte (r = 1.000, p = 0.01), erythrocyte (r = 1.000, p = 0.003), and platelet counts (r = 0.841, p = 0.036). Significantly increased BUN levels (P < 0.05) correlated with the decrease in RBC-AChE activities (r = - 0.997, p = 0.047) and with the decrease in absolute red blood cell (r = - 0.883, p = 0.020) and lymphocyte (r = - 0.825, p = 0.043) counts; increased (P < 0.05) total plasma protein levels correlated with the decrease in RBC-AChE activities (r = -0.998, p = 0.043), absolute red blood cell (r = - 0.998, p = 0.040), lymphocyte (r = - 0.893, p = 0.017), and platelet (r = -0.855, p = 0.030) counts. The physiological responses correlated with the erythrocyte acetylcholinesterase inhibition could be considered as early indicators or warning responses of bovine exposures to organophosphorus pesticides (OPs).  相似文献   
289.
Here we review mechanisms and factors influencing contaminant exposure among terrestrial vertebrate wildlife. There exists a complex mixture of biotic and abiotic factors that dictate potential for contaminant exposure among terrestrial and semi-terrestrial vertebrates. Chemical fate and transport in the environment determine contaminant bioaccessibility. Species-specific natural history characteristics and behavioral traits then play significant roles in the likelihood that exposure pathways, from source to receptor, are complete. Detailed knowledge of natural history traits of receptors considered in conjunction with the knowledge of contaminant behavior and distribution on a site are critical when assessing and quantifying exposure. We review limitations in our understanding of elements of exposure and the unique aspects of exposure associated with terrestrial and semi-terrestrial taxa. We provide insight on taxa-specific traits that contribute, or limit exposure to, transport phenomenon that influence exposure throughout terrestrial systems, novel contaminants, bioavailability, exposure data analysis, and uncertainty associated with exposure in wildlife risk assessments. Lastly, we identify areas related to exposure among terrestrial and semi-terrestrial organisms that warrant additional research.  相似文献   
290.
A multiresidue method was assessed for the determination of several pesticides (organochlorine, organophosphorus, pyrethroids, triazole, amidine) using gas chromatography/mass spectrometry. The extraction of pesticides was carried out by liquid-liquid extraction (LLE) and solid-phase extraction (SPE) using two types of columns (CN and C18). The extracts were cleaned by the addition of florisil, the pesticides were separated by capillary column gas chromatography and detected by mass spectrometry in the electron impact mode. The extraction using C18 column provided the best results for most of the analyzed pesticides. The majority of pesticides recoveries from the four fruits and vegetables (apples, pears, tomatoes and pepper) were greater than 60%. Linearity and precision were satisfactory. The estimated limits of detection and limits of quantification ranged from 0.01 to 0.1 mg/kg and from 0.02 to 0.3 mg/kg, respectively. The proposed procedure was found to be useful for the multiresidue analyses of pesticides in agricultural products for routine monitoring programs.  相似文献   
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