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Stomata are less responsive to environmental stimuli in high background ozone in Dactylis glomerata and Ranunculus acris Full text
2013
Wagg, Serena | Mills, Gina | Hayes, Felicity | Wilkinson, Sally | Davies, William J.
Two mesotrophic grassland species, Ranunculus acris and Dactylis glomerata were exposed to a range of ozone treatments (16.2–89.5 ppb 24 h mean) and two watering regimes under naturally fluctuating photosynthetically active radiation (PAR), vapour pressure deficit (VPD) and temperature. Stomatal conductance was measured throughout the experiments, and the combined data set (>1000 measurements) was analysed for effects of low and high ozone on responses to environmental stimuli. We show that when D. glomerata and R. acris were grown in 72.6–89.5 ppb ozone the stomata consistently lose the ability to respond, or have reduced response, to naturally fluctuating environmental conditions in comparison to their response in low ozone. The maximum stomatal conductance (gmax) was also significantly higher in the high ozone treatment for D. glomerata. We discuss the hypotheses for the reduced sensitivity of stomatal closure to a changing environment and the associated implications for ozone flux modelling.
Show more [+] Less [-]Adaptive microbial population shifts in response to a continuous ethanol blend release increases biodegradation potential Full text
2013
Ma, Jie | Nossa, Carlos W. | Xiu, Zongming | Rixey, William G. | Alvarez, Pedro J.J.
The fate of fuel releases largely depends on the poorly-understood response in microbial community structure and function. Here, we evaluate the impacts to the microbial community resulting from a pilot-scale continuous release (10 months) of a 10% v:v ethanol solution mixed with benzene and toluene (50 mg/L each). Microbial population shifts were characterized by pyrosequencing-based 16S rRNA analysis and by quantitative PCR targeting Bacteria, Archaea, and functional genes for methanogenesis (mcrA), acetogenesis (fhs) and aerobic degradation of aromatic hydrocarbons (PHE), which could occur in hypoxic micro-environments. The release stimulated microbial growth, increased species richness and diversity, and selected for genotypes involved in fermentative degradation (the relative abundance of mcrA and fhs increased 18- and 6-fold, respectively). The growth of putative hydrocarbon degraders and commensal anaerobes, and increases in microbial diversity and in degradation rates suggest an adaptive response that increases the potential for natural attenuation of ethanol blend releases.
Show more [+] Less [-]Assessment of potential climate change impacts on peatland dissolved organic carbon release and drinking water treatment from laboratory experiments Full text
2013
Tang, R. | Clark, J.M. | Bond, T. | Graham, N. | Hughes, D. | Freeman, C.
Assessment of potential climate change impacts on peatland dissolved organic carbon release and drinking water treatment from laboratory experiments Full text
2013
Tang, R. | Clark, J.M. | Bond, T. | Graham, N. | Hughes, D. | Freeman, C.
Catchments draining peat soils provide the majority of drinking water in the UK. Over the past decades, concentrations of dissolved organic carbon (DOC) have increased in surface waters. Residual DOC can cause harmful carcinogenic disinfection by-products to form during water treatment processes. Increased frequency and severity of droughts combined with and increased temperatures expected as the climate changes, have potentials to change water quality. We used a novel approach to investigate links between climate change, DOC release and subsequent effects on drinking water treatment. We designed a climate manipulation experiment to simulate projected climate changes and monitored releases from peat soil and litter, then simulated coagulation used in water treatment. We showed that the ‘drought’ simulation was the dominant factor altering DOC release and affected the ability to remove DOC. Our results imply that future short-term drought events could have a greater impact than increased temperature on DOC treatability.
Show more [+] Less [-]Assessment of potential climate change impacts on peatland dissolved organic carbon release and drinking water treatment from laboratory experiments Full text
2013
Tang, R. | Clark, Joanna M. | Bond, T. | Graham, N. | Hughes, D. | Freeman, C.
Catchments draining peat soils provide the majority of drinking water in the UK. Over the past decades, concentrations of dissolved organic carbon (DOC) have increased in surface waters. Residual DOC can cause harmful carcinogenic disinfection by-products to form during water treatment processes. Increased frequency and severity of droughts combined with and increased temperatures expected as the climate changes, have potentials to change water quality. We used a novel approach to investigate links between climate change, DOC release and subsequent effects on drinking water treatment. We designed a climate manipulation experiment to simulate projected climate changes and monitored releases from peat soil and litter, then simulated coagulation used in water treatment. We showed that the ‘drought’ simulation was the dominant factor altering DOC release and affected the ability to remove DOC. Our results imply that future short-term drought events could have a greater impact than increased temperature on DOC treatability.
Show more [+] Less [-]Nature and sources of particle associated polycyclic aromatic hydrocarbons (PAH) in the atmospheric environment of an urban area Full text
2013
Callén, M.S. | López, J.M. | Iturmendi, A. | Mastral, A.M.
The total PAH associated to the airborne particulate matter (PM10) was apportioned by one receptor model based on positive matrix factorization (PMF) in an urban environment (Zaragoza city, Spain) during February 2010–January 2011. Four sources associated with coal combustion, gasoline, vehicular and stationary emissions were identified, allowing a good modelling of the total PAH (R2 = 0.99). A seasonal behaviour of the four factors was obtained with higher concentrations in the cold season. The NE direction was one of the predominant directions showing the negative impact of industrial parks, a paper factory and a highway located in that direction. Samples were classified according to hierarchical cluster analysis obtaining that, episodes with the most negative impact on human health (the highest lifetime cancer risk concentrations), were produced by a higher contribution of stationary and vehicular emissions in winter season favoured by high relative humidity, low temperature and low wind speed.
Show more [+] Less [-]Modeling of air pollutant removal by dry deposition to urban trees using a WRF/CMAQ/i-Tree Eco coupled system Full text
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.
Show more [+] Less [-]Life stage-specific effects of the fungicide pyrimethanil and temperature on the snail Physella acuta (Draparnaud, 1805) disclose the pitfalls for the aquatic risk assessment under global climate change Full text
2013
Seeland, Anne | Albrand, Jennifer | Oehlmann, Jörg | Müller, Ruth
It can be suggested that the combined stress of pesticide pollution and suboptimal temperature influences the sensitivity of life stages of aquatic invertebrates differently.The embryo, juvenile, half- and full-life-cycle toxicity tests performed with the snail Physella acuta at different concentrations (0.06–0.5 or 1.0 mg L−1) of the model fungicide pyrimethanil at 15, 20 and 25 °C revealed, that pyrimethanil caused concentration-dependent effects at all test temperatures. Interestingly, the ecotoxicity of pyrimethanil was higher at lower (suboptimal) temperature for embryo hatching and F1 reproduction, but its ecotoxicity for juvenile growth and F0 reproduction increased with increasing temperature.The life-stage specific temperature-dependent ecotoxicity of pyrimethanil and the high fungicide susceptibility of the invasive snail clearly demonstrate the complexity of pesticide–temperature interactions and the challenge to draw conclusions for the risk of pesticides under the impact of global climate change.
Show more [+] Less [-]Air Quality Standards for Particulate Matter (PM) at high altitude cities Full text
2013
Bravo Alvarez, H. | Sosa Echeverria, R. | Sanchez Alvarez, P. | Krupa, S.
The Air Quality Standards for Particulate Matter (PM) at high altitude urban areas in different countries, must consider the pressure and temperature due to the effect that these parameters have on the breath volume.This paper shows the importance to correct Air Quality Standards for PM considering pressure and temperature at different altitudes. Specific factors were suggested to convert the information concerning PM, from local to standard conditions, and adjust the Air Quality Standards for different high altitudes cities. The correction factors ranged from: 1.03 for Santiago de Chile to 1.47 for El Alto Bolivia. Other cities in this study include: Mexico City, México; La Paz, Bolivia; Bogota, Cali and Medellin, Colombia; Quito, Ecuador and Cuzco, Peru.If these corrections are not considered, the atmospheric concentrations will be underestimated.
Show more [+] Less [-]Global climate change: Impact of diurnal temperature range on mortality in Guangzhou, China Full text
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.
Show more [+] Less [-]Characterization and influence of biochars on nitrous oxide emission from agricultural soil Full text
2013
Wang, Zhenyu | Zheng, Hao | Luo, Ye | Deng, Xia | Herbert, Stephen | Xing, Baoshan
Extensive use of biochar to mitigate N2O emission is limited by the lack of understanding on the exact mechanisms altering N2O emissions from biochar-amended soils. Biochars produced from giant reed were characterized and used to investigate their influence on N2O emission. Responses of N2O emission varied with pyrolysis temperature, and the reduction order of N2O emission by biochar (BC) was: BC200 ≈ BC600 > BC500 ≈ BC300 ≈ BC350 > BC400. The reduced emission was attributed to enhanced N immobilization and decreased denitrification in the biochar-amended soils. The remaining polycyclic aromatic hydrocarbons (PAHs) in low-temperature biochars (300–400 °C) played a major role in reducing N2O emission, but not for high-temperature biochars (500–600 °C). Removal of phenolic compounds from low-temperature (200–400 °C) biochars resulted in a surprising reduction of N2O emission, but the mechanism is still unknown. Overall, adding giant reed biochars could reduce N2O evolution from agricultural soil, thus possibly mitigating global warming.
Show more [+] Less [-]Calibration and field evaluation of polar organic chemical integrative sampler (POCIS) for monitoring pharmaceuticals in hospital wastewater Full text
2013
Bailly, Emilie | Levi, Yves | Karolak, Sara
The Polar Organic Chemical Integrative Sampler (POCIS) is a new tool for the sampling of organic pollutants in water. We tested this device for the monitoring of pharmaceuticals in hospital wastewater. After calibration, a field application was carried out in a French hospital for six pharmaceutical compounds (Atenolol, Prednisolone, Methylprednisolone, Sulfamethoxazole, Ofloxacin, Ketoprofen).POCIS were calibrated in tap water and wastewater in laboratory conditions close to relevant environmental conditions (temperature, flow velocity). Sampling rates (Rs) were determined and we observed a significant increase with flow velocity and temperature. Whatever the compound, the Rs value was lower in wastewater and the linear phase of uptake was shorter.POCIS were deployed in a hospital sewage pipe during four days and the estimated water concentrations were close to those obtained with twenty-four hour composite samples.
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