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11.
Xiaofei Wang Brent J. Williams 《Journal of the Air & Waste Management Association (1995)》2013,63(4):492-499
Aerosol emissions from toy cars with electric motors were characterized. Particle emission rates from the toy cars, as high as 7.47 × 107 particles/s, were measured. This emission rate is lower than other indoor sources such as smoking and cooking. The particles emitted from toy cars are generated from spark discharges inside the electric motors that power the toy cars. Size distribution measurements indicated that most particles were below 100 nm in diameter. Copper was the dominant inorganic species in these particles. By deploying aerosol mass spectrometers, high concentrations of particulate organic matter were also detected and characterized in detail. Several organic compounds were identified using a thermal desorption aerosol gas chromatography. The mass size distribution of particulate organic matter was bimodal. The formation mechanism of particulate organic matter from toy cars was elucidated.Implications:?A possible new source of indoor air pollution, particles from electric motors in toy cars, was identified. This study characterized aerosol emissions from toy cars in detail. Most of these particles have a diameter less than 100 nm. Copper and some organics are the major components of these particles. Conditions that minimize these emissions were determined. 相似文献
12.
Bonifacio HF Maghirang RG Auvermann BW Razote EB Murphy JP Harner JP 《Journal of the Air & Waste Management Association (1995)》2012,62(3):350-361
Open beef cattle feedlots emit various air pollutants, including particulate matter (PM) with equivalent aerodynamic diameter of 10 microm or less (PM10); however limited research has quantified PM10 emission rates from feedlots. This research was conducted to determine emission rates of PM10 from large cattle feedlots in Kansas. Concentrations of PM10 at the downwind and upwind edges of two large cattle feedlots (KS1 and KS2) in Kansas were measured with tapered element oscillating microbalance (TEOM) PM10 monitors from January 2007 to December 2008. Weather conditions at the feedlots were also monitored. From measured PM10 concentrations and weather conditions, PM10 emission rates were determined using reverse modeling with the American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model (AERMOD). The two feedlots differed significantly in median PM10 emission flux (1.60 g/m2-day for KS1 vs. 1.10 g/m2-day for KS2) but not in PM10 emission factor (27 kg/1000 head-day for KS1 and 30 kg/1000 head-day KS2). These emission factors were smaller than published U.S. Environmental Protection Agency (EPA) emission factor for cattle feedlots. 相似文献
13.
Importance of Sediment–Water Interactions in Coeur d’Alene Lake,Idaho, USA: Management Implications 总被引:1,自引:0,他引:1
Kuwabara JS Carter JL Topping BR Fend SV Woods PF Berelson WM Balistrieri LS 《Environmental management》2003,32(3):348-359
A field study at Coeur dAlene Lake, Idaho, USA, was conducted between October 1998 and August 2001 to examine the potential importance of sediment–water interactions on contaminant transport and to provide the first direct measurements of the benthic flux of dissolved solutes of environmental concern in this lake. Because of potential ecological effects, dissolved zinc and orthophosphate were the solutes of primary interest. Results from deployments of an in situ flux chamber indicated that benthic fluxes of dissolved Zn and orthophosphate were comparable in magnitude to riverine inputs. Tracer analyses and benthic-community metrics provided evidence that solute benthic flux were diffusion-controlled at the flux-chamber deployment sites. That is, effects of biomixing (or bioturbation) and ground-water interactions did not strongly influence benthic flux. Remediation efforts in the river might not produce desired water-quality effects in the lake because imposed shifts in concentration gradients near the sediment–water interface would generate a benthic feedback response. Therefore, development of water-quality models to justify remediation strategies requires consideration of contaminant flux between the water column and underlying sediment in basins that have been affected by long-term (decadal) anthropogenic activities. 相似文献
14.
Integrity of chloroplast membranes is essential to photosynthesis. Loss of thylakoid membrane integrity has been proposed as a consequence of ozone (O(3)) exposure and therefore may be a mechanistic basis for decreased photosynthetic rates commonly associated with ozone exposure. To investigate this hypothesis, Pinus ponderosa seedlings were exposed to ambient air or ozone concentrations maintained at 0.15 or 0.30 microliter l(-1) for 10 h day(-1) for 51 days during their second growing season. Over the course of the study, foliage samples were periodically collected for thylakoid membrane, chlorophyll and protein analyses. Additionally, gas-exchange measurements were made in conjunction with foliage sampling to verify that observed chloroplastic responses were associated with ozone-induced changes in photosynthesis.Needles exposed to elevated ozone exhibited decreases in chlorophyll a and b content. The decreases were dependent on the duration and intensity of ozone exposure. When based on equal amounts of chlorophyll, ozone-exposed sample tissue exhibited an increase in total protein. When based on equal amounts of protein, ozone-exposed samples exhibited an increase in 37 kDa proteins, possibly consisting of breakdown products, and a possible decrease in 68 kDa proteins, Rubisco small subunit. There was also a change in the ratio of Photosystem I protein complexes CPI and CPII that may have contributed to decreased photosynthesis. Net photosynthetic rates were decreased in the high ozone treatment suggesting that observed structural and biochemical changes in the chloroplast were associated with alterations of the photosynthetic process. 相似文献
15.
Stream Invertebrate Communities, Water Quality, and Land-Use Patterns in an Agricultural Drainage Basin of Northeastern Nebraska, USA 总被引:2,自引:0,他引:2
We used invertebrate bioassessment, habitat analysis, geographic information system analysis of land use, and water chemistry
monitoring to evaluate tributaries of a degraded northeast Nebraska, USA, reservoir. Bimonthly invertebrate collections and
monthly water chemistry samples were collected for two years on six stream reaches to identify sources contributing to reservoir
degradation and test suitability of standard rapid bioassessment methods in this region. A composite biotic index composed
of seven commonly used metrics was effective for distinguishing between differentially impacted sites and responded to a variety
of disturbances. Individual metrics varied greatly in precision and ability to discriminate between relatively impacted and
unimpacted stream reaches. A modified Hilsenhoff index showed the highest precision (reference site CV = 0.08) but was least
effective at discriminating among sites. Percent dominance and the EPT (number of Ephemeroptera, Plecoptera, and Trichoptera
taxa) metrics were most effective at discriminating between sites and exhibited intermediate precision. A trend of higher
biotic integrity during summer was evident, indicating seasonal corrections should differ from other regions. Poor correlations
were evident between water chemistry variables and bioassessment results. However, land-use factors, particularly within 18-m
riparian zones, were correlated with bioassessment scores. For example, there was a strong negative correlation between percentage
of rangeland in 18-m riparian zones and percentage of dominance in streams (r
2
= 0.90, P < 0.01). Results demonstrate that standard rapid bioassessment methods, with some modifications, are effective for use in this agricultural
region of the Great Plains and that riparian land use may be the best predictor of stream biotic integrity. 相似文献
16.
Timothy R. H. Pearson Sandra Brown Brent Sohngen Jennifer Henman Sara Ohrel 《Mitigation and Adaptation Strategies for Global Change》2014,19(8):1209-1222
There is general consensus that carbon (C) sequestration projects in forests are a relatively low cost option for mitigating climate change, but most studies on the subject have assumed that transaction costs are negligible. The objectives of the study were to examine transaction costs for forest C sequestration projects and to determine the significance of the costs based on economic analyses. Here we examine four case studies of active C sequestration projects being implemented in tropical countries and developed for the C market. The results from the case studies were then used with a dynamic forest and land use economic model to investigate how transaction costs affect the efficiency and cost of forest C projects globally. In the case studies transaction costs ranged from 0.38 to 27 million US dollars ($0.09 to $7.71/t CO2) or 0.3 to 270 % of anticipated income depending principally on the price of C and project size. The three largest cost categories were insurance (under the voluntary market; 41–89 % of total costs), monitoring (3–42 %) and regulatory approval (8–50 %). The global analysis indicated that most existing estimates of marginal costs of C sequestration are underestimated by up to 30 % because transaction costs were not included. 相似文献
17.
18.
Multiple paternity was recently observed in a population of the brown smoothhound shark, Mustelus henlei, from Las Barrancas, Baja California Sur, Mexico, with litters demonstrating the greatest percentage of multiple paternity for any shark species (93 % of litters and an average number of sires = 2.3). To determine whether this frequency is consistent elsewhere in the species’ range, 4 polymorphic microsatellite loci were used to determine the frequency of multiple paternity in 18 litters of M. henlei from Santa Catalina Island, CA, sampled in 2004, 2008, and 2012. Multiple paternity varied among sampling years with 2004 demonstrating multiple sires for 40 % of sampled litters (n = 10) with an average of 1.4 sires per litter and 2008/2012 demonstrating a total lack of multiply sired litters (n = 8). Although multiple paternity was detected in this study, the range of frequencies observed is lower than that observed in the Mexican population. Based on these findings, investigators should take location into consideration when assessing the existence of multiple paternity in future studies of elasmobranch species. 相似文献
19.
Ian C. Gilby Lauren J. N. Brent Emily E. Wroblewski Rebecca S. Rudicell Beatrice H. Hahn Jane Goodall Anne E. Pusey 《Behavioral ecology and sociobiology》2013,67(3):373-381
Coalitionary aggression occurs when at least two individuals jointly direct aggression at one or more conspecific targets. Scientists have long argued that this common form of cooperation has positive fitness consequences. Nevertheless, despite evidence that social bond strength (which is thought to promote coalition formation) is correlated with fitness in primates, cetaceans, and ungulates, few studies have directly examined whether coalitionary aggression improves reproductive success. We tested the hypothesis that among free-ranging chimpanzees (Pan troglodytes schweinfurthii), participation in coalitionary aggression increases reproductive output. Using 14 years of genetic and behavioral data from Gombe National Park, Tanzania, we found that coalitionary aggression increased a male’s chances of (A) siring offspring, compared to other males of similar dominance rank, and (B) ascending in rank, a correlate of future reproductive output. Because male chimpanzees form coalitions with many others within a complex network, we used social network analysis to identify the types of connections correlated with these fitness benefits. The beneficiaries of coalitionary aggression were males with the highest “betweenness”—that is, those who tended to have coalition partners who themselves did not form coalitions with each other. This suggests that beyond simply recognizing third-party relationships, chimpanzees may use this knowledge to choose coalition partners. If so, this is a significant step forward in our knowledge of the adaptive value of social intelligence. Regardless of mechanism, however, this is the first evidence of genetic benefits of coalitionary aggression in this species, and therefore has important implications for understanding the evolution of cooperation. 相似文献
20.
Dennis J. Paustenbach Tibor T. Sarlos Brent L. Finley David A. Jeffrey Michael J. Ungs 《Chemosphere》1991,23(11-12)
Conservative models were used to estimate the airborne concentrations of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) vapor and particulates originating from soil containing 100 ppb TCDD. The upper-bound estimates were 3.25 pg/m3 of airborne TCDD vapor on-site and 0.51 pg/m3 for TCDD vapor 100 meters downwind. The TCDD air concentration on-site due to suspended particulate is estimated to be 1.4 pg/m3, based on a TSP level of 0.07 mg/m3. Assuming 70 years of continuous exposure to these concentrations, the upper-bound cancer risks determined from the Jury model were estimated to be 9.4 × 10−6 to 1.1 × 10−4 and 1.5 × 10−6 to 1.7 × 10−5 for inhalation of on- and off-site vapor, respectively, and 4.1 × 10−6 to 4.6 × 10−5 for dust inhalation. Since few sites have average soil concentrations as high as 100 ppb TCDD, this worst-case analysis indicates that inhalation will rarely, if ever, be a significant route of exposure to TCDD-contaminated soil. Experimental results support this claim and point to much lower risk estimates (8.4 × 10−9 to 9.9 × 10−8), suggesting that the parameters used in the Jury model are likely to overestimate the actual airborne levels of TCDD at contaminated sites. 相似文献