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Carbon fluxes from an urban tropical grassland Texte intégral
2015
Ng, B.J.L. | Hutyra, L.R. | Nguyen, H. | Cobb, A.R. | Kai, F.M. | Harvey, C. | Gandois, L.
Turfgrass covers a large fraction of the urbanized landscape, but the carbon exchange of urban lawns is poorly understood. We used eddy covariance and flux chambers in a grassland field manipulative experiment to quantify the carbon mass balance in a Singapore tropical turfgrass. We also assessed how management and variations in environmental factors influenced CO2 respiration. Standing aboveground turfgrass biomass was 80 gC m−2, with a mean ecosystem respiration of 7.9 ± 1.1 μmol m−2 s−1. The contribution of autotrophic respiration was 49–76% of total ecosystem respiration. Both chamber and eddy covariance measurements suggest the system was in approximate carbon balance. While we did not observe a significant relationship between the respiration rates and soil temperature or moisture, daytime fluxes increased during the rainy interval, indicating strong overall moisture sensitivity. Turfgrass biomass is small, but given its abundance across the urban landscape, it significantly influences diurnal CO2 concentrations.
Afficher plus [+] Moins [-]A multibiomarker approach to explore interactive effects of propranolol and fluoxetine in marine mussels Texte intégral
2015
Franzellitti, Silvia | Buratti, Sara | Du, Bowen | Haddad, Samuel P. | Chambliss, C Kevin | Brooks, Bryan W. | Fabbri, Elena
A multi-biomarker approach, including several lysosomal parameters, activity and mRNA expression of antioxidant enzymes, and DNA damage, was employed to investigate the nominal effects of 0.3 ng/L fluoxetine (FX) and 0.3 ng/L propranolol (PROP) alone or in combination (0.3 ng/L FX + 0.3 ng/L PROP) on Mediterranean mussels after a 7 day treatment. FX co-exposure appears to facilitate PROP bioaccumulation because PROP only accumulated in digestive gland of FX + PROP treated mussels. Lysosomal parameters were significantly impaired by FX + PROP treatment, while no clear antioxidant responses at the catalytic and transcriptional levels were observed. Biomarker responses led to a “medium stress level” diagnosis in FX + PROP treated mussels, according to the Expert System, whereas 0.3 ng/L PROP or FX alone did not induce consistent stress conditions. These findings suggest vulnerability of coastal marine mussels to FX and PROP contamination at environmentally relevant levels.
Afficher plus [+] Moins [-]Assessing levels and seasonal variations of current-use pesticides (CUPs) in the Tuscan atmosphere, Italy, using polyurethane foam disks (PUF) passive air samplers Texte intégral
2015
Estellano, Victor H. | Pozo, Karla | Efstathiou, Christos | Pozo, Katerine | Corsolini, Simonetta | Focardi, S. (Silvano)
Polyurethane foam disks (PUF) passive air samplers (PAS) were deployed over 4 sampling periods of 3–5-months (≥ 1 year) at ten urban and rural locations throughout the Tuscany Region. The purpose was to assess the occurrence and seasonal variations of ten current-use pesticides (CUPs). PUF disk extracts were analyzed using GC–MS. The organophosphates insecticides; chlorpyrifos (3–580 pg m−3) and chlorpyrifos-methyl (below detection limit – to 570 pg m−3) presented the highest levels in air, and showed seasonal fluctuation coinciding with the growing seasons. The relative proportion urban/(urban + rural) ranged from 0.4 to 0.7 showing no differences between urban and rural concentrations. Air back trajectories analysis showed air masses passing over agricultural fields and potentially enhancing the drift of pesticides into the urban sites. This study represents the first information regarding CUPs in the atmosphere of Tuscany region using PAS-PUF disk.
Afficher plus [+] Moins [-]Contribution of coated humic acids calculated through their surface coverage on nano iron oxides for ofloxacin and norfloxacin sorption Texte intégral
2015
Peng, Hongbo | Liang, Ni | Li, Hao | Chen, Fangyuan | Zhang, Di | Pan, Bo | Xing, Baoshan
Sorption of organic contaminants on organo-mineral complexes has been investigated extensively, but the sorption contribution of mineral particles was not properly addressed before calculating KOC, especially for ionic organic contaminants. We measured the surface coverage of a humic acid (HA) on nano iron oxides (n-Fe2O3) in a series of synthesized organo-mineral complexes. The contribution of the coated HA to ofloxacin (OFL) and norfloxacin (NOR) sorption in HA–n-Fe2O3 complexes was over 80% of the total sorption with the surface coverage of 36% and fOC of 1.6%. All the coated HA showed higher sorption to NOR and OFL in comparison to the original HA, suggesting HA fractionation and/or physical re-conformation during organo-mineral complex formation. The decreased KOC with multilayer coating may suggest the importance of site-specific interactions for OFL sorption, while the increased KOC with multilayer coating may suggest the importance of partitioning in hydrophobic region for NOR sorption.
Afficher plus [+] Moins [-]The contrasting responses of soil microorganisms in two rice cultivars to elevated ground-level ozone Texte intégral
2015
Feng, Youzhi | Yu, Yongjie | Tang, Haoye | Zu, Qianhui | Zhu, Jianguo | Lin, Xiangui
Although elevated ground-level O3 has a species–specific impact on plant growth, the differences in soil biota responses to O3 pollution among rice cultivars are rarely reported. Using O3 Free-Air Concentration Enrichment, the responses of the rhizospheric bacterial communities in the O3-tolerant (YD6) and the O3-sensitive (IIY084) rice cultivars to O3 pollution and their differences were assessed by pyrosequencing at rice tillering and anthesis stages. Elevated ground-level O3 negatively influenced the bacterial community in cultivar YD6 at both rice growth stages by decreasing the bacterial phylogenetic diversities and response ratios. In contrast, in cultivar IIY084, the bacterial community responded positively at the rice tillering stage under O3 pollution. However, several keystone bacterial guilds were consistently negatively affected by O3 pollution in two rice cultivars. These findings indicate that continuously O3 pollution would negatively influence rice agroecosystem and the crop cultivar is important in determining the soil biota responses to elevated O3.
Afficher plus [+] Moins [-]Mining web-based data to assess public response to environmental events Texte intégral
2015
Cha, YoonKyung | Stow, Craig A.
We explore how the analysis of web-based data, such as Twitter and Google Trends, can be used to assess the social relevance of an environmental accident. The concept and methods are applied in the shutdown of drinking water supply at the city of Toledo, Ohio, USA. Toledo's notice, which persisted from August 1 to 4, 2014, is a high-profile event that directly influenced approximately half a million people and received wide recognition. The notice was given when excessive levels of microcystin, a byproduct of cyanobacteria blooms, were discovered at the drinking water treatment plant on Lake Erie. Twitter mining results illustrated an instant response to the Toledo incident, the associated collective knowledge, and public perception. The results from Google Trends, on the other hand, revealed how the Toledo event raised public attention on the associated environmental issue, harmful algal blooms, in a long-term context. Thus, when jointly applied, Twitter and Google Trend analysis results offer complementary perspectives. Web content aggregated through mining approaches provides a social standpoint, such as public perception and interest, and offers context for establishing and evaluating environmental management policies.
Afficher plus [+] Moins [-]Embryonic eggshell thickness erosion: A literature survey re-assessing embryo-induced eggshell thinning in birds Texte intégral
2015
Orłowski, Grzegorz | Hałupka, Lucyna
Although eggshell thinning has been described mainly in the context of environmental pollution, it can also be the effect of reproductive changes induced by a developing embryo. On the basis of a literature survey of 25 bird species (26 published papers) we reviewed data on embryo-induced eggshell thinning (EET) in three groups of birds: precocials, semi-precocials and altricials. The average EET at the equator of the eggs was 6.4% (median = 4.7%). Our review did not confirm a general prediction of elevated EET at the egg equator in precocial species: altricial birds exhibited the highest EET (average = 12.0%), followed by precocials (7.6%) and semi-precocials (4.2%). We make certain critical recommendations based on the results of this study. Studies aiming to assess variation in eggshell thickness should examine intrinsic factors affecting shell properties of avian eggs, like thickness, which are the result of anatomical or reproductive changes.
Afficher plus [+] Moins [-]Day-to-day variability of toxic events induced by organic compounds bound to size segregated atmospheric aerosol Texte intégral
2015
Topinka, Jan | Rossner, Pavel | Milcová, Alena | Schmuczerová, Jana | Pěnčíková, Kateřina | Rossnerová, Andrea | Ambrož, Antonín | Štolcpartová, Jitka | Bendl, Jan | Hovorka, Jan | Machala, Miroslav
This study quantified the temporal variability of concentration of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs), genotoxicity, oxidative DNA damage and dioxin-like activity of the extractable organic matter (EOM) of atmospheric aerosol particles of aerodynamic diameter (dae, μm) coarse (1 < dae < 10), upper- (0.5 < dae < 1) and lower-accumulation (0.17 < dae < 0.5) and ultrafine (<0.17) fractions. The upper accumulation fraction formed most of the aerosol mass for 22 of the 26 study days and contained ∼44% of total c-PAHs, while the ultrafine fraction contained only ∼11%. DNA adduct levels suggested a crucial contribution of c-PAHs bound to the upper accumulation fraction. The dioxin-like activity was also driven primarily by c-PAH concentrations. In contrast, oxidative DNA damage was not related to c-PAHs, as a negative correlation with c-PAHs was observed. These results suggest that genotoxicity and dioxin-like activity are the major toxic effects of organic compounds bound to size segregated aerosol, while oxidative DNA damage is not induced by EOM.
Afficher plus [+] Moins [-]Chronic effects of the ionic liquid [C4mim][Cl] towards the microalga Scenedesmus quadricauda Texte intégral
2015
Deng, Yun | Beadham, Ian | Wu, Jie | Chen, Xiao-Di | Hu, Lan | Gu, Jun
Chronic effects of the ionic liquid [C4mim][Cl] (mp 73 °C) towards the microalga, Scenedesmus quadricauda were studied by flow cytometry, monitoring multiple endpoints of cell density, esterase activity, membrane integrity, reactive oxygen species and chlorophyll fluorescence. Toxicity was clearly in evidence, and although increased esterase activity indicated hormesis during initial exposure to [C4mim][Cl], inhibition of both esterase activity and chlorophyll fluorescence became apparent after 3 days. Cell density was also decreased by culturing with [C4mim][Cl], but this effect was clearly concentration-dependent and only became significant during the second half of the experiment. In contrast, [C4mim][Cl] had only a modest effect on reactive oxygen species (ROS) and caused little damage to cell membranes.
Afficher plus [+] Moins [-]Decadal re-evaluation of contaminant exposure and productivity of ospreys (Pandion haliaetus) nesting in Chesapeake Bay Regions of Concern Texte intégral
2015
Lazarus, Rebecca S. | Rattner, Barnett A. | McGowan, Peter C. | Hale, Robert C. | Schultz, Sandra L. | Karouna-Renier, Natalie K. | Ottinger, Mary Ann
The last large-scale ecotoxicological study of ospreys (Pandion haliaetus) in Chesapeake Bay was conducted in 2000–2001 and focused on U.S. EPA-designated Regions of Concern (ROCs; Baltimore Harbor/Patapsco, Anacostia/middle Potomac, and Elizabeth Rivers). In 2011–2012, ROCs were re-evaluated to determine spatial and temporal trends in productivity and contaminants. Concentrations of p,p′-DDE were low in eggs and below the threshold associated with eggshell thinning. Eggs from the Anacostia/middle Potomac Rivers had lower total PCB concentrations in 2011 than in 2000; however, concentrations remained unchanged in Baltimore Harbor. Polybrominated diphenyl ether flame retardants declined by 40%, and five alternative brominated flame retardants were detected at low levels. Osprey productivity was adequate to sustain local populations, and there was no relation between productivity and halogenated contaminants. Our findings document continued recovery of the osprey population, declining levels of many persistent halogenated compounds, and modest evidence of genetic damage in nestlings from industrialized regions.
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