Modelling assessment of PM10 exposure control policies in Northern Italy

To assess the impact of three different emission reduction scenarios on PM10 concentrations in Northern Italy, the TCAM multiphase model has been applied in the framework of the CityDelta III-CAFE EU project. The considered domain, that is characterized by high urban and industrial emissions and a dense road traffic, due to frequently stagnating meteorological conditions is often affected by severe PM10 levels, far from the European standard regulations. The impact evaluation has been performed in terms of both yearly mean values and 50 g/m³ exceedance days for the 2004 Base Case simulation. The results show that the three selected emission reduction scenarios up to 2020 improve air quality all over the domain, in particular, in the area with higher emission density.     

Combining a generic process-based productivity model and a statistical classification method to predict the presence and absence of tree species in the Pacific Northwest,U.S.A.

Although long-lived tree species experience considerable environmental variation over their life spans, their geographical distributions reflect sensitivity mainly to mean monthly climatic conditions. We introduce an approach that incorporates a physiologically based growth model to illustrate how a half-dozen tree species differ in their responses to monthly variation in four climatic-related variables: water availability, deviations from an optimum temperature, atmospheric humidity deficits, and the frequency of frost. Rather than use climatic data directly to correlate with a species’ distribution, we assess the relative constraints of each of the four variables as they affect predicted monthly photosynthesis for Douglas-fir, the most widely distributed species in the region. We apply an automated regression-tree analysis to create a suite of rules, which differentially rank the relative importance of the four climatic modifiers for each species, and provide a basis for predicting a species’ presence or absence on 3737 uniformly distributed U.S. Forest Services’ Forest Inventory and Analysis (FIA) field survey plots. Results of this generalized rule-based approach were encouraging, with weighted accuracy, which combines the correct prediction of both presence and absence on FIA survey plots, averaging 87%. A wider sampling of climatic conditions throughout the full range of a species’ distribution should improve the basis for creating rules and the possibility of predicting future shifts in the geographic distribution of species.     

Combustion and inorganic bromine emission of waste printed circuit boards in a high temperature furnace

High temperature combustion experiments of waste printed circuit boards (PCBs) were conducted using a lab-scale system featuring a continuously-fed drop tube furnace. Combustion efficiency and the occurrence of inorganic bromine (HBr and Br₂) were systematically studied by monitoring the main combustion products continuously. The influence of furnace temperature (T) was studied from 800 to 1400 °C, the excess air factor (EAF) was varied from 1.2 to 1.9 and the residence time in the high temperature zone (RT_HT) was set at 0.25, 0.5, or 0.75 s.Combustion efficiency depends on temperature, EAF and RT_HT; temperature has the most significant effect. Conversion of organic bromine from flame retardants into HBr and Br₂ depends on temperature and EAF. Temperature has crucial influence over the ratio of HBr to Br₂, whereas oxygen partial pressure plays a minor role. The two forms of inorganic bromine seem substantially to reach thermodynamic equilibrium within 0.25 s. High temperature is required to improve the combustion performance: at 1200 °C or higher, an EAF of 1.3 or more, and a RT_HT exceeding 0.75 s, combustion is quite complete, the CO concentration in flue gas and remained carbon in ash are sufficiently low, and organobrominated compounds are successfully decomposed (more than 99.9%).According to these results, incineration of waste PCBs without preliminary separation and without additives would perform very well under certain conditions; the potential precursors for brominated dioxins formation could be destroyed efficiently. Increasing temperature could decrease the volume percentage ratio of Br₂/HBr in flue gas greatly.     

汽油加生物添加剂对发动机废气排放的影响研究

通过发动机的台架试验,系统研究了将一种热带植物提取物作为添加剂加入到不同成分的汽油中对汽油机废气排放特性的影响．结果表明：对于93^#高清洁汽油和93^#成分汽油,除了未燃碳氢(HC)略有上升外,其他排放物如氮氧化物NOx、一氧化碳等有所减少,CO2排放有明显的改善．对于乙醇汽油,则HC和CO2略有上升．     

Effect of steam hydration on performance of lime sorbent for CO2 capture

Lime is considered a feasible sorbent for the capture of CO₂ from large stationary sources. The positive attributes of a natural source material, low cost and lack of harmful by-products are offset by rapid deterioration in performance and high regeneration temperature. Performance can be improved by hydrating the lime using steam. We investigate a steam hydration process wherein lime is hydrated for 5 min at 300 °C and atmospheric pressure in a mixture of steam and CO₂. The experiments consisted of 10 capture cycles with 60% of the lime active at the end. Extrapolation using a decay model suggests a residual carbonation level of 48%, significantly higher than the 8% achieved by dry lime cycles. The cost of replacement sorbent under these conditions is less than $1/t of CO₂ captured. The hydrated lime process also reduces the thermal load, for heating and cooling, by half as well as the inventory, and therefore solids handling, by a factor 5 over dry lime. The introduction of the hydration reaction provides another exothermic reaction for heat management.     

Suspended Particulate Matter Distribution in Rural-Industrial Satna and in Urban-Industrial South Delhi

An air quality sampling program was designed and implemented to collect the baseline concentrations of respirable suspended particulates (RSP = PM₁₀), non-respirable suspended particulates (NRSP) and fine suspended particulates (FSP = PM_2.5). Over a three-week period, a 24-h average concentrations were calculated from the samples collected at an industrial site in Southern Delhi and compared to datasets collected in Satna by Envirotech Limited, Okhla, Delhi in order to establish the characteristic difference in emission patterns. PM_2.5, PM₁₀, and total suspended particulates (TSP) concentrations at Satna were 20.5 ± 6.0, 102.1 ± 41.1, and 387.6 ± 222.4 μg m⁻³ and at Delhi were 126.7 ± 28.6, 268.6 ± 39.1, and 687.7 ± 117.4 μg m⁻³. Values at Delhi were well above the standard limit for 24-h PM_2.5 United States National Ambient Air Quality Standards (USNAAQS; 65 μg m⁻³), while values at Satna were under the standard limit. Results were compared with various worldwide studies. These comparisons suggest an immediate need for the promulgation of new PM_2.5 standards. The position of PM₁₀ in Delhi is drastic and needs an immediate attention. PM₁₀ levels at Delhi were also well above the standard limit for 24-h PM₁₀ National Ambient Air Quality Standards (NAAQS; 150 μg m⁻³), while levels at Satna remained under the standard limit. PM_2.5/PM₁₀ values were also calculated to determine PM_2.5 contribution. At Satna, PM_2.5 contribution to PM₁₀ was only 20% compared to 47% in Delhi. TSP values at Delhi were well above, while TSP values at Satna were under, the standard limit for 24-h TSP NAAQS (500 μg m⁻³). At Satna, the PM₁₀ contribution to TSP was only 26% compared to 39% in Delhi. The correlation between PM₁₀, PM_2.5, and TSP were also calculated in order to gain an insight to their sources. Both in Satna and in Delhi, none of the sources was dominant a varied pattern of emissions was obtained, showing the presence of heterogeneous emission density and that nonrespirable suspended particulate (NRSP) formed the greatest part of the particulate load.     

Human impacts on methane emission from mangrove ecosystems in India

This study deals with the emission of methane in relation to changing environmental conditions and human impact, in three mangrove ecosystems of south India. Time-varying fluxes of methane adopting the close chamber technique were used to estimate CH₄ emission from an unpolluted site (Pichavaram mangroves) and two polluted sites viz. (1) Ennore Creek mangroves (affected by fertilizer effluents and crude oil discharges) and (2) Adyar estuary mangroves (affected by the discharges of organic and industrial wastes), covering monthly and seasonal variations. The results indicate annual average CH₄ emissions of 7.4, 5.02 and 15.4 mg m⁻² h⁻¹ from the sediment–water interface of the Pichavaram, Ennore Creek and Adyar estuary respectively. Emission characteristics obtained at Pichavaram mangroves represent a natural variability with changing physico-chemical factors, whereas the emission characteristics at Ennore Creek and Adyar estuary mangroves show anthropogenic influence. Several environmental factors such as oxygen availability, organic matter, soil physical and chemical properties, in addition to human-mediated interventions have been identified as influencing emission rates in the mangrove ecosystems. Preliminary CH₄ emission estimates for the mangrove ecosystems along the Indian sub- continent and the tropical and subtropical coastline of the world by linear extrapolation based on surface area range from 0.05 to 0.37 and 2.8 to 19.25 Tg CH₄ year⁻¹ respectively. Our results also highlight the impact of human activities on future emission of methane from the mangrove ecosystems. Received: 3 March 1999 / Accepted: 14 September 1999     

Field monitoring of volatile organic compounds using passive air samplers in an industrial city in Japan

Highly portable, sensitive, and selective passive air samplers were used to investigate ambient volatile organic compound (VOC) levels at multiple sampling sites in an industrial city, Fuji, Japan. We determined the spatial distributions of 27 species of VOCs in three campaigns: Mar (cold season), May (warm season), and Nov (mild season) of 2004. In all campaigns, toluene (geometric mean concentration, 14.0microg/m3) was the most abundant VOC, followed by acetaldehyde (4.76microg/m3), and formaldehyde (2.58microg/m3). The spatial distributions for certain VOCs showed characteristic patterns: high concentrations of benzene and formaldehyde were typically found along major roads, whereas high concentrations of toluene and tetrachloroethylene (PCE) were usually found near factories. The spatial distribution of PCE observed was extremely consistent with the diffusion pattern calculated from Pollutant Release and Transfer Register data and meteorological data, indicated that passive air samplers are useful for determining the sources and distributions of ambient VOCs.     

Estimation and characterization of PCDD/Fs and dioxin-like PCBs from Chinese iron foundries

The iron foundry industry is considered to be a potential source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study investigated the emission factors and total emission amounts of PCDD/Fs and dioxin-like polychlorinated biphenyls (DL-PCBs) from iron foundries in China. The concentrations and the World Health Organization toxicity equivalents (WHO-TEQs) are presented and the congener profiles are discussed in this paper.In the present work, 26 fly ash samples were collected and tested to quantify the PCDD/Fs and DL-PCBs generated by 14 plants of different scales, and five stack gas samples were collected from two (named as EFG and LFG) of those plants. The emission levels of PCDD/Fs and DL-PCBs indicated that hot-air cupolas had lower emissions than cold-air cupolas. When iron ore lump and sinter were used as raw material, the emission factors were about 250 ng TEQ t⁻¹ of product. However, if the raw material was scrap, the emission factors varied owing to the different contents of organic materials in the raw materials. It was found that the mean WHO-TEQ values of PCDD/Fs and DL-PCBs were 144 and 34.2 pg Nm⁻³ in stack gas and 20.0 and 1.58 pg g⁻¹ in fly ash. In multiple tests, it was estimated that the mean emission factors of PCDD/Fs and DL-PCBs were 365 and 10.9 ng WHO-TEQ t⁻¹ released to residue and 2719 and 555 ng TEQ t⁻¹ released to air. The total emission amounts of PCDD/Fs and DL-PCBs from Chinese iron foundries with cupola furnaces released to residue and air were 16.8 and 146 g WHO-TEQ in 2008, respectively.     

Emission characterization of unintentionally produced persistent organic pollutants from iron ore sintering process in China

Emission of unintentionally produced persistent organic pollutants (Unintentional POPs), including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychorinated biphenyls (PCBs), hexachlorobenzene (HxCBz) and pentachlorobenzene (PeCBz), were investigated in four typical iron ore sintering plants in China. The emission factors and annual mass releases of the Unintentional POPs were calculated. The results indicated that PCDFs contributed more than 60% to the overall toxic equivalent quantity (TEQ) values, while the contribution of the dl-PCBs is relatively low, and only in the range of 8-9%. The dominant congeners of PCDD/Fs and dl-PCBs contributing most to the total TEQ were 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and PCB-126. With regard to the TEQ contributions, the most abundant homologues were PeCDFs and HxCDD/Fs, followed by PeCDDs and non-ortho dl-PCB, whereas HpCDD/Fs, OCDD/Fs and mono-ortho dl-PCBs almost made no contributions. Due to the massive use of recycled waste in the feeding materials, the average emission factor of PCDD/Fs and dl-PCBs of the four plants was 3.95 μg WHO-TEQ ton⁻¹. Based on the results, the annual release of PCDD/Fs and dl-PCBs in 2007-2009 were estimated to be 2070 g, 2212 g, and 2307 g WHO-TEQ, respectively.