细化搜索
结果 361-370 的 1,956
Does urban vegetation mitigate air pollution in northern conditions? 全文
2013
Setälä, Heikki | Viippola, Viljami | Rantalainen, Anna-Lea | Pennanen, Arto | Yli-Pelkonen, Vesa
It is generally accepted that urban vegetation improves air quality and thereby enhances the well-being of citizens. However, empirical evidence on the potential of urban trees to mitigate air pollution is meager, particularly in northern climates with a short growing season. We studied the ability of urban park/forest vegetation to remove air pollutants (NO2, anthropogenic VOCs and particle deposition) using passive samplers in two Finnish cities. Concentrations of each pollutant in August (summer; leaf-period) and March (winter, leaf-free period) were slightly but often insignificantly lower under tree canopies than in adjacent open areas, suggesting that the role of foliage in removing air pollutants is insignificant. Furthermore, vegetation-related environmental variables (canopy closure, number and size of trees, density of understorey vegetation) did not explain the variation in pollution concentrations. Our results suggest that the ability of urban vegetation to remove air pollutants is minor in northern climates.
显示更多 [+] 显示较少 [-]Novel biospectroscopy sensor technologies towards environmental health monitoring in urban environments 全文
2013
Obinaju, Blessing E. | Martin, Francis L.
Biospectroscopy is an emerging inter-disciplinary field that exploits the application of sensor technologies [e.g., Fourier-transform infrared spectroscopy, Raman spectroscopy] to lend novel insights into biological questions. Methods involved are relatively non-destructive so samples can subsequently be analysed by more conventional approaches, facilitating deeper mechanistic insights. Fingerprint spectra are derived and these consist of wavenumber–absorbance intensities; within a typical biological experiment, a complex dataset is quickly generated. Biological samples range from biofluids to cytology to tissues derived from human or sentinel sources, and analyses can be carried out ex vivo or in situ in living tissue. A reference range of a designated normal state can be derived; anything outside this is potentially atypical and discriminating chemical entities identified. Computational approaches allow one to minimize within-category confounding factors. Because of ease of sample preparation, low-cost and high-throughput capability, biospectroscopy approaches herald a new greener means of environmental health monitoring in urban environments.
显示更多 [+] 显示较少 [-]BaP (PAH) air quality modelling exercise over Zaragoza (Spain) using an adapted version of WRF-CMAQ model 全文
2013
(Roberto),
Benzo(a)pyrene (BaP) is one of the most dangerous PAH due to its high carcinogenic and mutagenic character. Because of this reason, the Directive 2004/107/CE of the European Union establishes a target value of 1 ng/m3 of BaP in the atmosphere.In this paper, the main aim is to estimate the BaP concentrations in the atmosphere by using last generation of air quality dispersion models with the inclusion of the transport, scavenging and deposition processes for the BaP. The degradation of the particulated BaP by the ozone has been considered. The aerosol–gas partitioning phenomenon in the atmosphere is modelled taking into a count that the concentrations in the gas and the aerosol phases. If the pre-existing organic aerosol concentrations are zero gas/particle equilibrium is established.The model has been validated at local scale with data from a sampling campaign carried out in the area of Zaragoza (Spain) during 12 weeks.
显示更多 [+] 显示较少 [-]Unravelling remote sensing signatures of plants contaminated with gasoline and diesel: An approach using the red edge spectral feature 全文
2013
Sanches, I.D. | Souza Filho, C.R. | Magalhães, L.A. | Quitério, G.C.M. | Alves, M.N. | Oliveira, W.J.
Pipeline systems used to transport petroleum products represent a potential source of soil pollution worldwide. The design of new techniques that may improve current monitoring of pipeline leakage is imperative. This paper assesses the remote detection of small leakages of liquid hydrocarbons indirectly, through the analysis of spectral features of contaminated plants. Leaf and canopy spectra of healthy plants were compared to spectra of plants contaminated with diesel and gasoline, at increasing rates of soil contamination. Contamination effects were observed both visually in the field and thorough changes in the spectral reflectance patterns of vegetation. Results indicate that the remote detection of small volumes of gasoline and diesel contaminations is feasible based on the red edge analysis of leaf and canopy spectra of plants. Brachiaria grass ranks as a favourable choice to be used as an indicator of HCs leakages along pipelines.
显示更多 [+] 显示较少 [-]Bioaccumulation of polybrominated diphenyl ethers and several alternative halogenated flame retardants in a small herbivorous food chain 全文
2013
She, Ya-Zhe | Wu, Jiang-Ping | Zhang, Ying | Peng, Ying | Mo, Ling | Luo, Xiao-Jun | Mai, Bi-Xian
Little is known about the bioaccumulation behavior of polybrominated diphenyl ethers (PBDEs) and other halogenated flame retardants (HFRs) in plants and in herbivores. In the present study, PBDEs and several alternative HFRs (AHFRs) were examined in a small herbivorous food chain (paddy soils–rice plant–apple snails) from an electronic waste recycling site in South China. Mean concentrations of total PBDEs were 40.5, 1.81, and 5.54 ng/g dry weight in the soils, rice plant, and apple snails, respectively. Levels of total AHFRs in the samples were comparable to or even higher than those of PBDEs. The calculated plant to soil concentration ratios for most AHFRs (0.05–3.40) were higher than those for PBDEs (0.02–0.23), indicating the greater bioavailability of the AHFRs in the rice plant. All PBDE congeners and Dechlorane Plus (DP) isomers were biomagnified from the rice plant to apple snails, with mean biomagnification factors (BMFs) of 1.1–5.0.
显示更多 [+] 显示较少 [-]Dechlorane Plus and its dechlorinated analogs from an e-waste recycling center in maternal serum and breast milk of women in Wenling, China 全文
2013
Ben, Yu-Jie | Li, Xing-Hong | Yang, You-Lin | Li, Long | Di, Jun-Ping | Wang, Wen-Yue | Zhou, Ren-Fang | Xiao, Ke | Zheng, Mei-Yun | Tian, Yuan | Xu, Xiao-Bai
We measured Dechlorane Plus (DP) and its dechlorinated analogs in the blood and milk from women living in e-waste recycling sites in Wenling of Taizhou region, China (n = 49). Both syn-DP and anti-DP were detected in all samples. Another compound, Cl11-DP, was detected in 45% and 84% of milk and serum samples, respectively. DP levels in blood and milk from residents living in the local environment >20 yrs (R20 group) were significantly higher than those living in Taizhou <3 yrs (R3 group) (p < 0.05). The milk/serum partition coefficient from the same women was approximately 0.43 and 0.47 for syn-DP and anti-DP, respectively. A similar value in milk compared with anti-DP/∑DPs (fanti) in serum suggested that stereoselective DP bio-accumulation did not occur during the DP transport from blood to milk. This result indicate that DP can bio-accumulate in blood and milk with the low milk/serum partition coefficient and similar blood and milk stereoselective bio-accumulation profiles.
显示更多 [+] 显示较少 [-]Modeling of air pollutant removal by dry deposition to urban trees using a WRF/CMAQ/i-Tree Eco coupled system 全文
2013
Cabaraban, Maria Theresa I. | Kroll, Charles N. | Hirabayashi, Satoshi | Nowak, David J.
A distributed adaptation of i-Tree Eco was used to simulate dry deposition in an urban area. This investigation focused on the effects of varying temperature, LAI, and NO2 concentration inputs on estimated NO2 dry deposition to trees in Baltimore, MD. A coupled modeling system is described, wherein WRF provided temperature and LAI fields, and CMAQ provided NO2 concentrations. A base case simulation was conducted using built-in distributed i-Tree Eco tools, and simulations using different inputs were compared against this base case. Differences in land cover classification and tree cover between the distributed i-Tree Eco and WRF resulted in changes in estimated LAI, which in turn resulted in variations in simulated NO2 dry deposition. Estimated NO2 removal decreased when CMAQ-derived concentration was applied to the distributed i-Tree Eco simulation. Discrepancies in temperature inputs did little to affect estimates of NO2 removal by dry deposition to trees in Baltimore.
显示更多 [+] 显示较少 [-]Effects of dietary selenium on the health and survival of captive wintering lesser scaup 全文
2013
Brady, Caroline | Petrie, Scott | Schummer, Michael | Badzinski, Shannon | Belzile, Nelson | Chen, Yu-Wei
Accumulation of selenium (Se) by lesser and greater scaup (Aythya affinis, A. marila) at staging and wintering areas could have contributed to the decline in their continental population. We exposed lesser scaup to background (0.8 μg/g), moderate (8.1 μg/g) and high (20.7 μg/g) levels of dietary Se in captivity and measured survival rates and indices of health in relation to hepatic Se concentrations. There was 100% survival in scaup exposed to Se for 10-weeks (average staging duration at Great Lakes), but ducks in the high treatment group had less lipids. There was 93% survival after 23-weeks (average wintering duration at Great Lakes), but no differences among treatment groups in body composition. There were no effects of Se on oxidative stress and cell-mediated immunity; rather we recorded immuno-stimulatory effects on antibody production. Results from our captive study suggest Se alone did not cause the continental decline in scaup populations.
显示更多 [+] 显示较少 [-]Sex differences in the accumulation of chlorinated dioxins in the cormorant (Phalacrocorax carbo): Implication of hepatic sequestration in the maternal transfer 全文
2013
Kubota, Akira | Yoneda, Kumiko | Tanabe, Shinsuke | Iwata, Hisato
This study focuses on gender-specific accumulation features of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in common (great) cormorants (Phalacrocorax carbo) collected from Lake Biwa, Japan. Male cormorants showed a tendency to have higher levels of PCDD/DFs and DL-PCBs than did females. For PCDDs, the male-to-female concentration ratio (M/F ratio) for each congener significantly decreased with the liver-to-muscle concentration ratio (Li/Mu ratio). For PCDFs, there also was a weak negative relationship between Li/Mu ratio and M/F ratio. In contrast, for DL-PCBs, M/F ratios showed no correlation with Li/Mu ratios, but increased with an increase in lipophilicity. These results, together with observations from prior studies, suggest that congener-specific hepatic sequestration may be a factor limiting the maternal transfer of PCDDs and, to a lesser extent, PCDFs. Maternal transfer of DL-PCBs seems to favor more lipophilic congeners in the cormorants.
显示更多 [+] 显示较少 [-]Dechlorination of PCBs in the rhizosphere of switchgrass and poplar 全文
2013
Meggo, Richard E. | Schnoor, Jerald L. | Hu, Dingfei
Polychlorinated biphenyl (PCB) congeners (PCB 52, 77, and 153) singly and in mixture were spiked and aged in soil microcosms and subsequently planted with switchgrass (Panicum virgatum) or poplar (Populus deltoids x nigra DN34). The planted reactors showed significantly greater reductions in PCB parent compounds when compared to unplanted systems after 32 weeks. There was evidence of reductive dechlorination in both planted and unplanted systems, but the planted microcosms with fully developed roots and rhizospheres showed greater biotransformation than the unplanted reactors. These dechlorination products accounted for approximately all of the molar mass of parent compound lost. Based on the transformation products, reductive dechlorination pathways are proposed for rhizospheric biotransformation of PCB 52, 77, and 153. This is the first report of rhizosphere biotransformation pathways for reductive dechlorination in marginally aerobic, intermittently flooded soil as evidenced by a mass balance on transformation products.
显示更多 [+] 显示较少 [-]