Contribution of residential wood combustion to PM10 levels in Portugal

Wood is commonly used in residential combustion for heating purposes; however, it can be a major source of air pollutants, namely fine particles, volatile organic compounds and carbon monoxide. Since 2004, the PM10 daily limit value has been surpassed in Portugal, and the European Commission has stated that plans and programs must be designed in order to reduce these levels. In Portugal, 18% of PM10 emissions are due to residential wood combustion, which may deeply impact the PM10 levels in the atmosphere. The main aim of this study is to investigate the impact of residential wood combustion on the air quality in Portugal. The air quality modelling system MM5/CHIMERE was applied over Portugal for a winter month, for the following three scenarios: the reference scenario, considering the actual emissions of PM10; scenario 1, where residential wood combustion emissions are not considered; and scenario 2, which takes into account a complete conversion from traditional fireplaces to certified appliances (with a 90% reduction in PM emissions). The residential wood combustion contribution to PM10 air quality concentration values during January 2007 ranges from 0 to 14 μg m^?3, with a mean contribution of 10 μg m^?3 in the Lisboa area and 6 μg m^?3 in the Porto region. Concerning the legislated values, the area where the daily average limit value (50 μg m^?3) is exceeded decreases by 46% in the simulation when residential combustion is not considered. The modelling results for scenario 2 are not significantly different from those for scenario 1. In summary, the regulation of the residential wood combustion sector is as an effective way to reduce the PM10 levels in the atmosphere as regards air quality plans and programs.     

Modeling the surface–atmosphere exchange of ammonia

New parameterizations for surface–atmosphere exchange of ammonia are presented for application in atmospheric transport models and compared with parameterizations of the literature. The new parameterizations are based on a combination of the results of three years of ammonia flux measurements over a grassland canopy (dominated by Lolium perenne and Poa trivialis) near Wageningen, the Netherlands and existing parameterizations from literature. First, a model for the surface–atmosphere exchange of ammonia that includes the concentration at the external leaf surface is derived and validated. Second, a parameterization for the stomatal compensation point (expressed as Γ_s, the ratio of [NH₄⁺]/[H⁺] in the leaf apoplast) that accounts for the observed seasonal variation is derived from the measurements. The new, temperature-dependent Γ_s describes the observed seasonal behavior very well. It is noted, however, that senescence of plants and field management practices will also influence the seasonal variation of Γ_s on a shorter timescale. Finally, a relation that links Γ_s to the atmospheric pollution level of the location through the ‘long-term’ NH₃ concentration in the air is proposed.     

WRF-Chem simulation of East Asian air quality: Sensitivity to temporal and vertical emissions distributions

This study develops fine temporal (seasonal, day-of-week, diurnal) and vertical allocations of anthropogenic emissions for the TRACE-P inventory and evaluates their impacts on the East Asian air quality prediction using WRF-Chem simulations in July 2001 at 30-km grid spacing against available surface measurements from EANET and NEMCC. For NO₂ and SO₂, the diurnal and vertical redistributions of emissions play essential roles, while the day-of-week variation is less important. When all incorporated, WRF-Chem best simulates observations of surface NO₂ and SO₂ concentrations, while using the default emissions produces the worst result. The sensitivity is especially large over major cities and industrial areas, where surface NO₂ and SO₂ concentrations are reduced by respectively 3–7 and 6–12 ppbv when using the scaled emissions. The incorporation of all the three redistributions of emissions simulates surface O₃ concentrations higher by 4–8 ppbv at night and 2–4 ppbv in daytime over broad areas of northern, eastern and central China. To this sensitivity, the diurnal redistribution contributes more than the other two.     

On-road traffic emissions in a megacity

A new annual bottom–up emission inventory of criteria pollutants and greenhouse gases from on-road mobile sources was developed for 2006 for the metropolitan area of Buenos Aires, Argentina, within a four-year regional project aimed at providing tools for chemical weather forecast in South America. Under the scarcity of local emission factors, we collected data from measuring campaigns performed in Argentina, Brazil, Chile and Colombia and compiled a data set of regional emission factors representative of Latin American fleets and driving conditions. The estimated emissions were validated with respect to downscaled national estimates and the EDGAR global emission database. Our results highlight the role of older technologies accounting in average for almost 80% of the emissions of all species. The area exhibits higher specific emissions than developed countries, with figures two times higher for criteria pollutants. We analyzed the effect on emissions of replacing gasoline by compressed natural gas, occurring in Argentina since 1995. We identified (i) a relationship between number of vehicles and a compound socioeconomic indicator, and (ii) time-lags in vehicle technologies between developed and developing countries, which can be respectively applied for spatial disaggregation and the development of projections for other Latin American cities. The results may also be employed to complement global emission inventories and by local policy makers as an environmental management tool.     

Using a reduced Common Representative Intermediates (CRIv2-R5) mechanism to simulate tropospheric ozone in a 3-D Lagrangian chemistry transport model

A reduced chemical scheme (CRIv2-R5) which describes ozone formation from the tropospheric degradation of methane and 22 emitted non-methane hydrocarbons and oxygenated volatile organic compounds has been applied in a global-3D chemistry transport model (STOCHEM). The scheme, which contains 220 species in 609 reactions, has been used to simulate ozone and its precursors for the meteorological year of 1998 and the results have been compared with those from STOCHEM runs with its original chemistry. Compared with the original chemistry scheme, the degradation of a larger number of more reactive VOCs in the CRI scheme results in the formation (and their consequent transportation) of more NO_x active reservoirs thus leading to formation of more ozone away from land-based sources. Conversely, the more reactive VOCs also lead to greater removal of OH in continental areas and greater formation of OH in marine environments. STOCHEM run with the CRI scheme simulates more ozone (by up to 10 ppb), which results in better agreement with observed vertical ozone profiles. The CRI scheme transforms the globally and annually integrated ozone budget for the considered year in STOCHEM from a net loss of ?55 Tg yr^?1 to a net gain of +50 Tg yr^?1.     

The application of profluorescent nitroxides to detect reactive oxygen species derived from combustion-generated particulate matter: Cigarette smoke – A case study

Reactive oxygen species (ROS) and related free radicals are considered to be key factors underpinning the various adverse health effects associated with exposure to ambient particulate matter. Therefore, measurement of ROS is a crucial factor for assessing the potential toxicity of particles. In this work, a novel profluorescent nitroxide, BPEAnit, was investigated as a probe for detecting particle-derived ROS. BPEAnit has a very low fluorescence emission due to inherent quenching by the nitroxide group, but upon radical trapping or redox activity, a strong fluorescence is observed. BPEAnit was tested for detection of ROS present in mainstream and sidestream cigarette smoke. In the case of mainstream cigarette smoke, there was a linear increase in fluorescence intensity with an increasing number of cigarette puffs, equivalent to an average of 101 nmol ROS per cigarette based on the number of moles of the probe reacted. Sidestream cigarette smoke sampled from an environmental chamber exposed BPEAnit to much lower concentrations of particles, but still resulted in a clearly detectible increase in fluorescence intensity with sampling time. It was calculated that the amount of ROS was equivalent to 50 ± 2 nmol per mg of particulate matter; however, this value decreased with ageing of the particles in the chamber. Overall, BPEAnit was shown to provide a sensitive response related to the oxidative capacity of the particulate matter. These findings present a good basis for employing the new BPEAnit probe for the investigation of particle-related ROS generated from cigarette smoke as well as from other combustion sources.     

Exporting natural capital: the foreign eco-footprint on Costa Rica and implications for sustainability

As the world economy ‘globalizes’, trade has become a major mechanism by which much of the human population supports its needs. While trade in resource commodities (natural income) can increase the well-being of people in both exporting and importing countries, it can also lead to depletion of natural capital and the loss of ecosystems integrity. In recent years, various researchers have attempted to address this problem using a consumption-based perspective on ecological change. Their work shows that the loss of ecosystem integrity in almost any region of the world can be attributed to both local and international consumer demand. This paper illustrates the utility of modified eco-footprint analysis in assessing export-related ecological change in Costa Rica. We quantify ecological footprint of consumers around the world on the productive ecosystems of Costa Rica, document the changing character of this footprint and highlight some of the linkages between production for export in Costa Rica and ecological degradation. We then discuss the implications of the increasing trade-based entanglement of nations for ecosystems and global sustainability.     

Impact of fires on the fauna of terrestrial arthropods in protected steppe ecosystems

The abundance of terrestrial arthropods in the Orenburgskii Nature Reserve has decreased since its establishment in 1989. At present, this parameter fluctuates considerably, and the species composition of arthropods is changing in favor of xerobiontic and eurybiontic species. These changes result from the absence of grazing load as well as from periodic fires. Therefore, it is necessary to organize controlled livestock grazing and reliable fire protection in reserved areas.     

Evaluating Conservation Program Success with Landsat and SWAT

In the United States, many state and federally funded conservation programs are required to quantify the water quality benefits resulting from their efforts. The objective of this research was to evaluate the impact of conservation practices subsidized by the Oklahoma Conservation Commission on phosphorus and sediment loads to Lake Wister. Conservation practices designed to increase vegetative cover in grazed pastures were evaluated using Landsat imagery and the Soil and Water Assessment Tool (SWAT). Several vegetative indices were derived from Landsat imagery captured before and after the implementation of conservation practices. Collectively, these indicators provided an estimate of the change in vegetative soil cover attributable to conservation practices in treated fields. Field characteristics, management, and changes in vegetative cover were used in the SWAT model to simulate sediment and phosphorus losses before and after practice implementation. Overall, these conservation practices yielded a 1.9% improvement in vegetative cover and a predicted sediment load reduction of 3.5%. Changes in phosphorus load ranged from a 1.0% improvement to a 3.5% increase, depending upon initial vegetative conditions. The use of fertilizers containing phosphorus as a conservation practice in low-productivity pastures was predicted by SWAT to increase net phosphorus losses despite any improvement in vegetative cover. This combination of vegetative cover analysis and hydrologic simulation was a useful tool for evaluating the effects of conservation practices at the basin scale and may provide guidance for the selection of conservation measures subsidized in future conservation programs.     

Effects of particle size on chemical speciation and bioavailability of copper to earthworms (Eisenia fetida) exposed to copper nanoparticles

To investigate the role of particle size on the oxidation, bioavailability, and adverse effects of manufactured Cu nanoparticles (NPs) in soils, we exposed the earthworm Eisenia ferida to a series of concentrations of commercially produced NPs labeled as 20- to 40-nm or < 100-nm Cu in artificial soil media. Effects on growth, mortality, reproduction, and expression of a variety of genes associated with metal homeostasis, general stress, and oxidative stress were measured. We also used X-ray absorption spectroscopy and scanning X-ray fluorescence microscopy to characterize changes in chemical speciation and spatial distribution of the NPs in soil media and earthworm tissues. Exposure concentrations of Cu NPs up to 65 mg kg(-1) caused no adverse effects on ecologically relevant endpoints. Increases in metallothionein expression occurred at concentrations exceeding 20 mg kg(-1) of Cu NPs and concentrations exceeding 10 mg kg(-1) of CuSO4. Based on the relationship of Cu tissue concentration to metallothionein expression level and the spatial distribution and chemical speciation of Cu in the tissues, we conclude that Cu ions and oxidized Cu NPs were taken up by the earthworms. This study suggests that oxidized Cu NPs may enter food chains from soil but that adverse effects in earthworms are likely to occur only at relatively high concentrations (> 65 mg Cu kg(-1) soil).