Contribution of primary and secondary sources to organic aerosol and PM2.5 at SEARCH network sites

Chemical tracer methods for determining contributions to primary organic aerosol (POA) are fairly well established, whereas similar techniques for secondary organic aerosol (SOA), inherently complicated by time-dependent atmospheric processes, are only beginning to be studied. Laboratory chamber experiments provide insights into the precursors of SOA, but field data must be used to test the approaches. This study investigates primary and secondary sources of organic carbon (OC) and determines their mass contribution to particulate matter 2.5 microm or less in aerodynamic diameter (PM2.5) in Southeastern Aerosol Research and Characterization (SEARCH) network samples. Filter samples were taken during 20 24-hr periods between May and August 2005 at SEARCH sites in Atlanta, GA (JST); Birmingham, AL (BHM); Centerville, AL (CTR); and Pensacola, FL (PNS) and analyzed for organic tracers by gas chromatography-mass spectrometry. Contribution to primary OC was made using a chemical mass balance method and to secondary OC using a mass fraction method. Aerosol masses were reconstructed from the contributions of POA, SOA, elemental carbon, inorganic ions (sulfate [SO4(2-)], nitrate [NO3-], ammonium [NH4+]), metals, and metal oxides and compared with the measured PM2.5. From the analysis, OC contributions from seven primary sources and four secondary sources were determined. The major primary sources of carbon were from wood combustion, diesel and gasoline exhaust, and meat cooking; major secondary sources were from isoprene and monoterpenes with minor contributions from toluene and beta-caryophyllene SOA. Mass concentrations at the four sites were determined using source-specific organic mass (OM)-to-OC ratios and gave values in the range of 12-42 microg m(-3). Reconstructed masses at three of the sites (JST, CTR, PNS) ranged from 87 to 91% of the measured PM2.5 mass. The reconstructed mass at the BHM site exceeded the measured mass by approximately 25%. The difference between the reconstructed and measured PM2.5 mass for nonindustrial areas is consistent with not including aerosol liquid water or other sources of organic aerosol.     

Airborne pollen in European and Asian parts of Istanbul

Pollen concentrations in the atmosphere of Istanbul, a city located between two continents, has been monitored for 1 year as part of a larger research program. The sampling sites were located in two different continents: the Asian part (AS) and the European part (EP). The sampling was performed in AS and EP of the city by using Hirst type volumetric method, and pollen grains of 58 and 62 taxa were identified in the two parts, respectively. The pollen spectrum reflected the floristic diversity of the region. The main pollen producers at the sites were characterized by some allergenic pollen and were identified as Cupressaceae/Taxaceae, Urticaceae, Pistacia sp., Quercus sp., Platanus sp., Fraxinus sp., and Xanthium sp. These pollen types contributed to the total pollen sum with a percentage of more than 80% at both monitoring sites. The highest amount of pollen grains was recorded in April. The greatest number of species was recorded in May, when 42 types (AS) and 44 types (EP) were present.     

PCDD/F contamination on surface soil in the vicinity of a hazardous waste incinerator: is it possible a different trend?

This study is the first to investigate the contamination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) on surface soils in the vicinity of the first hazardous waste incinerator of Turkey. In the study, 24 soil samples were taken from a 1625-m-radius circle whose center is the stack of the incinerator. This process was repeated 1 year later. Since the acquired average PCDD/F concentrations of the two sampling campaigns (0.05 and 0.02 ng WHO-toxic equivalent (TEQ)/kg) were meaningfully low compared to the related literatures, a new sampling campaign was carried out to control this inconsistency, but this time in a foreign laboratory (0.56 ng WHO-TEQ/kg). In the same period, eight gas samples were taken from the stack under different operational conditions of the facility. According to the evaluations of the findings, the geographical-meteorological data of the study area and the specific operational conditions of the facility corroborate the concentrations of the first and the second soil samplings rather than the third one. The major underlying reason for the inconsistency of the soil concentrations may be the fact that the data analysis procedures used by the laboratories are different. The author suggests a hypothesis which argues that the soils in the vicinity of a hazardous waste incinerator may have significantly lower concentration levels than in related literatures.     

Determination of selected heavy metals in air samples from the northern part of Jordan

In this work, the atmospheric concentrations of selected heavy metals including lead (Pb), iron (Fe), cadmium (Cd), copper (Cu), nickel (Ni), manganese (Mn), and zinc (Zn) were measured for two different sampling sites (urban and rural) in the northern part of Jordan (Irbid city). Samples were collected according to a certain schedule for 1 year. High volume air samplers and glass fiber filters were used to collect the samples. Collected samples were digested using a mixture of analytical grade nitric acid and analytical grade hydrochloric acid, and analyzed to evaluate the levels of heavy metals by atomic absorption spectrophotometry. Six heavy metals (Pb, Fe, Cu, Ni, Mn, and Zn) were measured in all samples; the concentrations of Cd and Co were not detected in Irbid atmosphere by atomic absorption spectroscopy. The results were used to determine the levels of heavy metal pollutants in air, possible sources, and to compare the levels of selected heavy metals in the two studied sites. Aerosols from the rural site have lower concentrations for all the metals compared to those from the urban site. The daily and monthly variations of the elements were investigated. All heavy metals in urban and rural sites reached maximum concentrations in June, July, and August. This is consistent with the increased activities leading to particulate matter emission during the summer period. The enrichment factors with respect to earth crust and correlation coefficients of heavy metals were investigated to predict the possible sources of heavy metals in air.     

Metals in sediments and mangrove oysters (Crassostrea rhizophorae) from the Caroni Swamp,Trinidad

Metals can have significant impacts on inhabitants of mangrove swamps as well as consumers of mangrove-associated fauna. Yet, for several Caribbean islands, assessments regarding the impact of metals on such ecosystems are particularly sparse. The present study investigated the distribution and potential impact of Cd, Cr, Cu, Ni, Pb and Zn in the Caroni Swamp, Trinidad and Tobago’s largest mangrove ecosystem. Surface sediments and mangrove oysters (Crassostrea rhizophorae) from 10 sites in the swamp were analysed for the 6 identified metals. The concentration ranges (in μg/g dry wt.) of metals in sediments from Caroni Swamp were: Zn (113.4–264.6), Cr (27–69.7), Ni (10.7–41.1) and Cu (11–40.7). Based on Canadian Sediment Quality Guidelines (CSQGs), metals in sediments posed a low to medium risk to aquatic life. The concentration ranges (in μg/g wet wt.) for metals in Crassostrea rhizophorae tissues were: Zn (123.2–660), Cu (4.2–12.3), Ni (0.1–5.5), Pb (0.1–0.9), Cr (0.2–0.3) and Cd (0.1–0.2). Multiple evaluations indicated that zinc posed a potential threat to the health of oyster consumers. Information from this study is vital for managing the Caroni Swamp, safeguarding the health of consumers of shellfish on this Caribbean island and serving as a useful baseline for future local and regional risk assessments.     

Empirical gas emission and oxidation measurement at cover soil of dumping site: example from Malaysia

Methane (CH₄) is one of the most relevant greenhouse gases and it has a global warming potential 25 times greater than that of carbon dioxide (CO₂), risking human health and the environment. Microbial CH₄ oxidation in landfill cover soils may constitute a means of controlling CH₄ emissions. The study was intended to quantify CH₄ and CO₂ emissions rates at the Sungai Sedu open dumping landfill during the dry season, characterize their spatial and temporal variations, and measure the CH₄ oxidation associated with the landfill cover soil using a homemade static flux chamber. Concentrations of the gases were analyzed by a Micro-GC CP-4900. Two methods, kriging values and inverse distance weighting (IDW), were found almost identical. The findings of the proposed method show that the ratio of CH₄ to CO₂ emissions was 25.4 %, indicating higher CO₂ emissions than CH₄ emissions. Also, the average CH₄ oxidation in the landfill cover soil was 52.5 %. The CH₄ and CO₂ emissions did not show fixed-pattern temporal variation based on daytime measurements. Statistically, a negative relationship was found between CH₄ emissions and oxidation (R ²?=?0.46). It can be concluded that the variation in the CH₄ oxidation was mainly attributed to the properties of the landfill cover soil.     

Factors affecting vehicle exhaust emissions,driver motivations as a mediator

Environmental Economics and Policy Studies - Reducing the negative effects of vehicle emissions is one of the main priorities for governments worldwide. Comprehensive understanding of the costs and...     

Modelling the connection between energy consumption and carbon emissions in North Africa: Evidence from panel models robust to cross-sectional dependence and slope heterogeneity

Environment, Development and Sustainability - This paper explored the link between energy consumption and carbon emissions in North Africa through an Environmental Kuznets Curve (EKC) framework....     

The potential effect of temperature-humidity index on productive and reproductive performance of buffaloes with different genotypes under hot conditions

The current study was aimed to investigate the impact of THI on productive and reproductive indices of PE and F₁ crosses (50% PE and 50% Italian buffaloes) and back crosses (BC) (75% PE and 25% Italian buffaloes) under hot conditions. In this study, 8385 records used PE (1914, 1518, and 1737), F₁ (387, 447, and 657), and BC (495, 585, and 645) for low, medium, and high THI, respectively. The high THI reduced the conception rate after first insemination in PE, F₁, and BC ((odds ratio, OR) = 1.187, P = 0.007; 2.361, <0.0001 and 1.603, <0.0001, respectively) when compared with low THI. But, stillbirth and calving condition were not significantly influenced by different THI levels in BC and F₁. BC was more bearable to the harsh environment; they possessed the highest incidence of conception after first insemination (72.70, 72.60, and 62.40%), producing live calves (98.50, 100, and 99.40%) with easy calving condition (98.50, 100, and 99.40%) when compared to PE and F₁ at different levels of THI, respectively. The average daily milk yield and peak of milk production were decreased in PE (4.02 and 5.12%), BC (13.33 and 10.95%), and F₁ (25.29 and 12.20%) from low to high THI. However, BC revealed no significant changes in days open, dry period, calving interval, gestation length, service per conception, and the first service post-partum at different levels of THI when compared with PE and F₁. Therefore, rearing BC is recommended for improving buffalo productive and reproductive performance under hot conditions.