خيارات البحث
النتائج 291 - 300 من 1,956
Ozone distribution in remote ecologically vulnerable terrain of the southern Sierra Nevada, CA النص الكامل
2013
Panek, Jeanne | Saah, David | Esperanza, Annie | Bytnerowicz, Andrzej | Fraczek, Witold | Cisneros, Ricardo
Ozone concentration spatial patterns remain largely uncharacterized across the extensive wilderness areas of the Sierra Nevada, CA, despite being downwind of major pollution sources. These natural areas, including four national parks and four national forests, contain forest species that are susceptible to ozone injury. Forests stressed by ozone are also more vulnerable to other agents of mortality, including insects, pathogens, climate change, and ultimately fire. Here we analyze three years of passive ozone monitor data from the southern Sierra Nevada and interpolate landscape-scale spatial and temporal patterns during the summer-through-fall high ozone concentration period. Segmentation analysis revealed three types of ozone exposure sub-regions: high, low, and variable. Consistently high ozone exposure regions are expected to be most vulnerable to forest mortality. One high exposure sub-region has been documented elsewhere as being further vulnerable to increased drought and fire potential. Identifying such hot-spots of forest vulnerability has utility for prioritizing management.
اظهر المزيد [+] اقل [-]Space and time resolved monitoring of airborne particulate matter in proximity of a traffic roundabout in Sweden النص الكامل
2013
Wilkinson, Kai E. | Lundkvist, Johanna | Netrval, Julia | Eriksson, Mats | Seisenbaeva, Gulaim A. | Kessler, Vadim G.
Concerns over exposure to airborne particulate matter (PM) are on the rise. Currently monitoring of PM is done on the basis of interpolating a mass of PM by volume (μg/m3) but has the drawback of not taking the chemical nature of PM into account. Here we propose a method of collecting PM at its emission source and employing automated analysis with scanning electron microscopy associated with EDS-analysis together with light scattering to discern the chemical composition, size distribution, and time and space resolved structure of PM emissions in a heavily trafficated roundabout in Sweden. Multivariate methods (PCA, ANOVA) indicate that the technogenic marker Fe follows roadside dust in spreading from the road, and depending on time and location of collection, a statistically significant difference can be seen, adding a useful tool to the repertoiré of detailed PM monitoring and risk assessment of local emission sources.
اظهر المزيد [+] اقل [-]Occurrence of estrogenic activities in second-grade surface water and ground water in the Yangtze River Delta, China النص الكامل
2013
Shi, Wei | Hu, Guanjiu | Chen, Sulan | Wei, Si | Cai, Xi | Chen, Bo | Feng, Jianfang | Hu, Xinxin | Wang, Xinru | Yu, Hongxia
Second-grade surface water and ground water are considered as the commonly used cleanest water in the Yangtze River Delta, which supplies centralized drinking water and contains rare species. However, some synthetic chemicals with estrogenic disrupting activities are detectable. Estrogenic activities in the second-grade surface water and ground water were surveyed by a green monkey kidney fibroblast (CV-1) cell line based ER reporter gene assay. Qualitative and quantitative analysis were further conducted to identify the responsible compounds. Estrogen receptor (ER) agonist activities were present in 7 out of 16 surface water and all the ground water samples. Huaihe River and Yangtze River posed the highest toxicity potential. The highest equivalent (2.2 ng E2/L) is higher than the predicted no-effect-concentration (PNEC). Bisphenol A (BPA) contributes to greater than 50% of the total derived equivalents in surface water, and the risk potential in this region deserves more attention and further research.
اظهر المزيد [+] اقل [-]Biodegradation of 17α-ethinylestradiol by heterotrophic bacteria النص الكامل
2013
Larcher, Simone | Yargeau, Viviane
The presence of the synthetic estrogen 17α-ethinylestradiol (EE2) in the environment is of increasing concern due to the endocrine disruption of aquatic organisms. Incomplete removal from wastewater (WW) is one of the main sources of EE2 in aquatic ecosystems, thus improving processes like biological WW treatment/activated sludge (AS) is becoming significantly important. There are opposing results regarding EE2 biodegradability by AS; one discrepancy is the efficacy of heterotrophic bacteria. This research demonstrated the ability of heterotrophs commonly present in AS (B. subtilis, P. aeruginosa, P. putida, R. equi, R. erythropolis, R. rhodochrous, R. zopfii) to remove EE2. R. rhodochrous was the most successful with no detectable EE2 after 48 h; the other bacteria achieved 21%–61% EE2 removal. No additive or synergistic effects were observed due to the combination of the bacterial cultures with maximum EE2 removals of 43% after 300 h.
اظهر المزيد [+] اقل [-]Global climate change: Impact of diurnal temperature range on mortality in Guangzhou, China النص الكامل
2013
Yang, Jun | Liu, Hua-Zhang | Ou, Chun-Quan | Lin, Guo-Zhen | Zhou, Qin | Shen, Gi-Chuan | Chen, Ping-Yan | Guo, Yuming
Diurnal temperature range (DTR) is an important meteorological indicator associated with global climate change, but little is known about the effects of DTR on mortality. We examined the effects of DTR on cause-/age-/education-specific mortality in Guangzhou, a subtropical city in China during 2003–2010. A quasi-Poisson regression model combined with distributed lag non-linear model was used to examine the effects of DTR, after controlling for daily mean temperature, air pollutants, season and day of the week. A 1 °C increase in DTR at lag 0–4 days was associated with a 0.47% (95% confidence interval: 0.01%–0.93%) increase in non-accidental mortality. Stroke mortality was most sensitive to DTR. Female, the elderly and those with low education were more susceptible to DTR than male, the youth and those with high education, respectively. Our findings suggest that vulnerable subpopulations should pay more attention to protect themselves from unstable daily weather.
اظهر المزيد [+] اقل [-]Effects of soil pollutants, biogeochemistry and microbiology on the distribution and composition of enchytraeid communities in urban and suburban holm oak stands النص الكامل
2013
Rota, Emilia | Caruso, Tancredi | Monaci, Fabrizio | Baldantoni, Daniela | De Nicola, Flavia | Iovieno, Paola | Bargagli, Roberto
Holm oaks form typical urban woodlands in the Mediterranean region. We aimed at characterizing the enchytraeid communities in these environments and searching for possible correlations with soil parameters, including the traffic contamination. Samples of litter and topsoil were collected at different spatial scales and seasons in Naples and Siena cities and in two suburban stands. Only the co-variation between pollution and other soil chemico-physical factors showed significant effects, whereas no direct effect of soil microbiology was detected. Some thermophilous Fridericia and Achaeta tolerate high concentrations of heavy metals and PAHs and their abundance was mainly determined by Ca bioavailability. Central-European mesophilous species increased significantly under more temperate environmental conditions. Different combinations of soil cohesiveness, grain size composition and moisture regime seem to select species of certain body sizes.
اظهر المزيد [+] اقل [-]Influence of land use on human bioaccessibility of metals in smelter-impacted soils النص الكامل
2013
Pelfrêne, Aurélie | Waterlot, Christophe | Douay, Francis
An investigation was undertaken to evaluate the empirical model developed by Pelfrêne et al. (2012), predicting the human bioaccessibility of Cd and Pb in smelter-contaminated agricultural topsoils, by including other soil uses: 50 urban and 65 woody habitat topsoils collected in the same area. The results showed that land use significantly affected the pseudototal metal concentrations and their oral bioaccessibility. However, whatever the soil's physicochemical parameters and degree of contamination, the ‘agricultural’ model can be used to simulate metal gastric bioaccessibility in urban and woody habitat soils. To simulate gastrointestinal bioaccessibility, this model can be used directly if the pseudototal metal concentrations are on the same order of magnitude as those usually recorded in the agricultural soils studied or after the use of a correction factor if these concentrations are greater. These results showed that the oral bioaccessibility predictions could be applicable for further environmental risk evaluation.
اظهر المزيد [+] اقل [-]Maternal effects of inducible tolerance against the toxic cyanobacterium Microcystis aeruginosa in the grazer Daphnia carinata النص الكامل
2013
Jiang, Xiaodong | Yang, Wei | Zhao, Shiye | Liang, Huishuang | Zhao, Yunlong | Chen, Liqiao | Li, Rui
Cyanobacterial blooms are becoming potent agents of natural selection in aquatic ecosystems because of their high production of some toxins and increased frequency in recent decades with eutrophication and climate change. Maternal exposure to the toxic Microcystis aeruginosa significantly increased the intrinsic rates of population increase, average life span, and net reproductive rates of a clone of the planktonic grazer Daphnia carinata in an offspring environment where cyanobacteria were present, but not for two additional clones. Offspring from mothers exposed to M. aeruginosa had lower intrinsic rates of population increase, average life span, and net reproductive rates than individuals from unexposed mothers when fed exclusively a green alga. These results suggest that benefits, costs, and clonal variations of maternal effects of inducible tolerance should be considered when trying to understand ecological consequences of cyanobacterial blooms since they can shape the trophic interactions between cyanobacteria and daphnids.
اظهر المزيد [+] اقل [-]Ionic profile of honey as a potential indicator of botanical origin and global environmental pollution النص الكامل
2013
Fermo, Paola | Beretta, Giangiacomo | Maffei Facino, Roberto | Gelmini, Fabrizio | Piazzalunga, Andrea
Aim of this study was to determine by Ion Chromatography ions (Na+, Ca++, Mg++, NH4+, Cl−, Br−, SO42−, NO3−, PO43−) in honeys (honeydew and floral nectar honeys) from different Italian Regions and from countries of the Western Balkan area. The compositional data were processed by multivariate analysis (PCA and HCA). Arboreal honeydew honeys from the Western Balkans had higher concentrations (from two to three times) of some environmental pollutants (Br−, SO42− and PO43− contents), due to industrial and agricultural activities, than those from Italian regions. The cationic profiles were very similar in both groups. Multivariate analysis indicated a clear difference between nectar honeys and arboreal/honeydew honeys (recognition of the botanical origin). These findings point to the potential of ionic constituents of honey as indicators of environmental pollution, botanical origin and authenticity.
اظهر المزيد [+] اقل [-]Evaluating the sub-lethal toxicity of PFOS and PFOA using rotifer Brachionus calyciflorus النص الكامل
2013
Zhang, Lilan | Niu, Junfeng | Li, Yang | Wang, Yujuan | Sun, Dong
The acute and chronic effects of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) on the rotifer Brachionus calyciflorus (B. calyciflorus) were investigated at the organismal and the population level. The acute toxicity of PFOS to rotifers was approximately 2.5-fold greater than that of PFOA. From 0.25 to 2.0 mg L−1, PFOS exhibited higher toxicity than PFOA on the F0-generation of B. calyciflorus, including effects on body size, juvenile periods, net reproductive rate, and generation time. Both PFOS and PFOA exposure induced a smaller egg size in B. calyciflorus, suggesting that these risks can be transferred from mother to offspring. The 28-day population growth studies showed that PFOS and PFOA reduced the population density and increased the mictic ratio. Our results demonstrated that both PFOS and PFOA had adverse effects on B. calyciflorus, not only at the individual level but also at the population level.
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