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Exploring the applicability of future air quality predictions based on synoptic system forecasts
2012
Yuval, | Broday, David M. | Alpert, Pinhas
For a given emissions inventory, the general levels of air pollutants and the spatial distribution of their concentrations are determined by the physiochemical state of the atmosphere. Apart from the trivial seasonal and daily cycles, most of the variability is associated with the atmospheric synoptic scale. A simple methodology for assessing future levels of air pollutants' concentrations based on synoptic forecasts is presented. At short time scales the methodology is comparable and slightly better than persistence and seasonal forecasts at categorical classification of pollution levels. It's utility is shown for air quality studies at the long time scale of a changing climate scenario, where seasonality and persistence cannot be used. It is demonstrated that the air quality variability due to changes in the pollution emissions can be expected to be much larger than that associated with the effects of climatic changes.
Показать больше [+] Меньше [-]A stomatal ozone flux–response relationship to assess ozone-induced yield loss of winter wheat in subtropical China
2012
Feng, Zhaozhong | Tang, Haoye | Uddling, Johan | Pleijel, Håkan | Kobayashi, Kazuhiko | Zhu, Jianguo | Oue, Hiroki | Guo, Wenshan
Stomatal ozone flux and flux–response relationships were derived for winter wheat (Triticum aestivum L.) grown under fully open-air ozone fumigation. A stomatal conductance (gₛₜₒ) model developed for wheat in Europe was re-parameterized. Compared to European model parameterizations, the main changes were that the VPD and radiation response functions were made less and more restrictive, respectively, and that the temperature function was omitted. The re-parameterized gₛₜₒ model performed well with an r² value of 0.76. The slope and intercept of the regression between observed and predicted gₛₜₒ were not significantly different from 1 to 0, respectively. An ozone uptake threshold of 12 nmol m⁻² s⁻¹ was judged most reasonable for the wheat flux–response relationship in subtropical China. Judging from both flux- and concentration-based relationships, the cultivars investigated seem to be more sensitive to ozone than European cultivars. The new flux–response relationship can be applied to ozone risk assessment in subtropical regions.
Показать больше [+] Меньше [-]Digestive utilization of ozone-exposed forage by rabbits (Oryctolagus cuniculus)
2012
Gilliland, Nicholas J. | Chappelka, Arthur H. | Muntifering, Russell B. | Booker, Fitzgerald L. | Ditchkoff, Stephen S.
A mixture of common Southern Piedmont (USA) grassland species (Lolium arundinacea, Paspalum dilatatum, Cynodon dactylon and Trifolium repens) was exposed to O₃ [ambient (non-filtered; NF) and twice-ambient (2X) concentrations] and fed to individually caged New Zealand white rabbits (Oryctolagus cuniculus) in a digestibility experiment. Forages and feed refusals were analyzed for concentrations of total cell wall constituents, lignin, crude protein, and soluble and hydrolyzable phenolic fractions. Neutral detergent fiber and acid detergent fiber digestibility by rabbits were significantly lower for 2X than NF forage. Decreased digestibility could not be attributed to lignin concentrations, but was associated with increased concentrations of acid-hydrolyzable and saponifiable phenolics. Exposure of forage to elevated O₃ resulted in decreased digestible dry matter intake by rabbits. Elevated O₃ concentrations could be expected to have a negative impact on forage quality, resulting in decreased nutrient utilization by mammalian herbivores in Southern Piedmont grasslands under projected future climate scenarios.
Показать больше [+] Меньше [-]Responses of native broadleaved woody species to elevated ozone in subtropical China
2012
Zhang, Weiwei | Feng, Zhaozhong | Wang, Xiaoke | Niu, Junfeng
To assess ozone sensitivity of subtropical broadleaved tree species and explore possible underlying mechanisms, six evergreen and two deciduous native species were exposed to either charcoal-filtered air or elevated O₃ (E-O₃, ∼150ppb) for one growing season. Initial visible symptoms in deciduous species appeared much earlier than those in evergreen species. The species which first showed visible symptoms also had the largest reductions in biomass. E-O₃ induced significant decreases in photosynthesis rate, chlorophyll content and antioxidant capacity but a significant increase in malondialdehyde content in two deciduous species and two evergreen species (Cinnamomum camphora and Cyclobalanopsis glauca). Except C. glauca, however, E-O₃ had no significant effects on stomatal conductance (gₛ), total phenols and ascorbate contents. Difference in O₃ sensitivity among all species was strongly attributed to specific leaf mass rather than gₛ. It suggests that some subtropical tree species will be threatened by rising O₃ concentrations in the near future.
Показать больше [+] Меньше [-]Enhancement of life cycle assessment (LCA) methodology to include the effect of surface albedo on climate change: Comparing black and white roofs
2012
Susca, Tiziana
Traditionally, life cycle assessment (LCA) does not estimate a key property: surface albedo. Here an enhancement of the LCA methodology has been proposed through the development and employment of a time-dependent climatological model for including the effect of surface albedo on climate. The theoretical findings derived by the time-dependent model have been applied to the case study of a black and a white roof evaluated in the time-frames of 50 and 100 years focusing on the impact on global warming potential. The comparative life cycle impact assessment of the two roofs shows that the high surface albedo plays a crucial role in offsetting radiative forcings. In the 50-year time horizon, surface albedo is responsible for a decrease in CO₂eq of 110–184 kg and 131–217 kg in 100 years. Furthermore, the white roof compared to the black roof, due to the high albedo, decreases the annual energy use of about 3.6–4.5 kWh/m².
Показать больше [+] Меньше [-]Forests under climate change and air pollution: Gaps in understanding and future directions for research
2012
Matyssek, R. | Wieser, G. | Calfapietra, C. | de Vries, W. | Dizengremel, P. | Ernst, D. | Jolivet, Y. | Mikkelsen, T.N. | Mohren, G.M.J. | Le Thiec, D. | Tuovinen, J.-P. | Weatherall, A. | Paoletti, E.
Forests in Europe face significant changes in climate, which in interaction with air quality changes, may significantly affect forest productivity, stand composition and carbon sequestration in both vegetation and soils. Identified knowledge gaps and research needs include: (i) interaction between changes in air quality (trace gas concentrations), climate and other site factors on forest ecosystem response, (ii) significance of biotic processes in system response, (iii) tools for mechanistic and diagnostic understanding and upscaling, and (iv) the need for unifying modelling and empirical research for synthesis. This position paper highlights the above focuses, including the global dimension of air pollution as part of climate change and the need for knowledge transfer to enable reliable risk assessment. A new type of research site in forest ecosystems (“supersites”) will be conducive to addressing these gaps by enabling integration of experimentation and modelling within the soil-plant-atmosphere interface, as well as further model development.
Показать больше [+] Меньше [-]Water quality in the inshore Great Barrier Reef lagoon: Implications for long-term monitoring and management
2012
Schaffelke, Britta | Carleton, John | Skuza, Michele | Zagorskis, Irena | Furnas, Miles J.
Coastal and inshore areas of the Great Barrier Reef lagoon receive substantial amounts of material from adjacent developed catchments, which can affect the ecological integrity of coral reefs and other inshore ecosystems. A 5-year water quality monitoring dataset provides a ‘base range’ of water quality conditions for the inshore GBR lagoon and illustrates the considerable temporal and spatial variability in this system. Typical at many sites were high turbidity levels and elevated chlorophyll a and phosphorus concentrations, especially close to river mouths. Water quality variability was mainly driven by seasonal processes such as river floods and sporadic wind-driven resuspension as well as by regional differences such as land use. Extreme events, such as floods, caused large and sustained increases in water quality variables. Given the highly variable climate in the GBR region, long-term monitoring of marine water quality will be essential to detect future changes due to improved catchment management.
Показать больше [+] Меньше [-]Linking coral river runoff proxies with climate variability, hydrology and land-use in Madagascar catchments
2012
Maina, Joseph | Moel, Hans de | Vermaat, Jan E. | Henrich Bruggemann, J. | Guillaume, Mireille M.M. | Grove, Craig A. | Madin, Joshua S. | Mertz-Kraus, Regina | Zinke, Jens
Understanding the linkages between coastal watersheds and adjacent coral reefs is expected to lead to better coral reef conservation strategies. Our study aims to examine the main predictors of environmental proxies recorded in near shore corals and therefore how linked near shore reefs are to the catchment physical processes. To achieve these, we developed models to simulate hydrology of two watersheds in Madagascar. We examined relationships between environmental proxies derived from massive Porites spp. coral cores (spectral luminescence and barium/calcium ratios), and corresponding time-series (1950–2006) data of hydrology, climate, land use and human population growth. Results suggest regional differences in the main environmental drivers of reef sedimentation: on annual time-scales, precipitation, river flow and sediment load explained the variability in coral proxies of river discharge for the northeast region, while El Niño-Southern Oscillation (ENSO) and temperature (air and sea surface) were the best predictors in the southwest region.
Показать больше [+] Меньше [-]Island shadow effects and the wave climate of the Western Tuamotu Archipelago (French Polynesia) inferred from altimetry and numerical model data
2012
Andréfouët, Serge | Ardhuin, Fabrice | Queffeulou, Pierre | Le Gendre, Romain
To implement a numerical model of atoll lagoon circulation, we characterized first the significant wave height (Hs) regime of the Western Tuamotu Archipelago and the local attenuation due to the protection offered by large atolls in the south Tuamotu. Altimetry satellite data and a WAVEWATCH III two-way nested wave model at 5km resolution from 2000 to 2010 were used. Correlation between altimetry and model was high (0.88) over the period. According to the wave model, the archipelago inner seas experienced attenuated Hs year-long with a yearly average Hs around 1.3m vs a minimum of 1.6m elsewhere. The island shadow effect is especially significant in the austral winter. In contrast with southern atolls, Western Tuamotu experienced only few days per year of Hs larger than 2.5m generated by very high Hs southern swell, transient western local storms, strong easterly winds, and during the passage of distant hurricanes.
Показать больше [+] Меньше [-]Principal Component Analysis as an Outlier Detection Tool for Polycyclic Aromatic Hydrocarbon Concentrations in Ambient Air
2012
Brown, Richard J. C. | Brown, Andrew S.
Principal component analysis has been used as a tool for the detection of potentially outlying observations in multivariate data sets of polycyclic aromatic hydrocarbon concentrations (PAHs) in ambient air. The outlier statistic developed is the vector distance of each observation at a given site from the origin of principal component space. It is shown that the success of this technique relies on the usually very strong correlation of concentrations of different PAHs in ambient air, such that any deviation from this correlation is noteworthy. Indeed, it is so strong that the first principal component has been omitted from the technique since it is related mostly to absolute concentration. The method has been successful in detecting observations with unusually high concentrations of one or more PAHs. Moreover, it has been possible to identify periods where the UK pollution climate was abnormal during periods of extreme weather. Advice and guidance for the practical use of the technique is also given.
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