Source apportionment for indoor air pollution: Current challenges and future directions.

Source apportionment (SA) for indoor air pollution is challenging due to the multiplicity and high variability of indoor sources, the complex physical and chemical processes that act as primary sources, sinks and sources of precursors that lead to secondary formation, and the interconnection with the outdoor environment. While the major indoor sources have been recognized, there is still a need for understanding the contribution of indoor versus outdoor-generated pollutants penetrating indoors, and how SA is influenced by the complex processes that occur in indoor environments. This paper reviews our current understanding of SA, through reviewing information on the SA techniques used, the targeted pollutants that have been studied to date, and their source apportionment, along with limitations or knowledge gaps in this research field. The majority (78 %) of SA studies to date focused on PM chemical composition/size distribution, with fewer studies covering organic compounds such as ketones, carbonyls and aldehydes. Regarding the SA method used, the majority of studies have used Positive Matrix Factorization (31 %), Principal Component Analysis (26 %) and Chemical Mass Balance (7 %) receptor models. The indoor PM sources identified to date include building materials and furniture emissions, indoor combustion-related sources, cooking-related sources, resuspension, cleaning and consumer products emissions, secondary-generated pollutants indoors and other products and activity-related emissions. The outdoor environment contribution to the measured pollutant indoors varies considerably (<10 %- 90 %) among the studies. Future challenges for this research area include the need for optimization of indoor air quality monitoring and data selection as well as the incorporation of physical and chemical processes in indoor air into source apportionment methodology.

Copper Accumulation Efficiency in Different Recombinant Microorganism Strains Available for Bioremediation of Heavy Metal-Polluted Waters.

The aim of this research was to investigate the bioremediation conditions of copper in synthetic water. In the present study, copper ions accumulation efficiency was determined using various genetically modified strains of Saccharomyces cerevisiae (EBY100, INVSc1, BJ5465, and GRF18), Pichia pastoris (X-33, KM71H), Escherichia coli (XL10 Gold, DH5α, and six types of BL21 (DE3)), and Escherichia coli BL21 (DE3) OverExpress expressing two different peroxidases. Viability tests of yeast and bacterial strains showed that bacteria are viable at copper concentrations up to 2.5 mM and yeasts up to 10 mM. Optical emission spectrometry with inductively coupled plasma analysis showed that the tolerance of bacterial strains on media containing 1 mM copper was lower than the tolerance of yeast strains at the same copper concentration. The E. coli BL21 RIL strain had the best copper accumulation efficiency (4.79 mg/L of culture normalized at an optical density of 1.00), which was 1250 times more efficient than the control strain. The yeast strain S. cerevisiae BJ5465 was the most efficient in copper accumulation out of a total of six yeast strains used, accumulating over 400 times more than the negative control strain. In addition, E. coli cells that internally expressed recombinant peroxidase from Thermobifida fusca were able to accumulate 400-fold more copper than cells that produced periplasmic recombinant peroxidases.

Comparison of fine particulate matter level, chemical content and oxidative potential derived from two dissimilar urban environments.

Urban airborne particles contain a wide spectrum of components, known to have harmful effects on human health. This study reports a detailed investigation of fine particulate matter (PM2.5), chemical content and oxidative potential derived from two different urban environments. During summer and winter, 20-day campaigns were conducted at Belgrade city center (urban-background site - UB) and Bor (urban-industrial site - UI). Using various analytical techniques, carbonaceous compounds, water-soluble inorganic ions, major and trace elements were determined, while the oxidative potential of PM2.5 was estimated by dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay (OPDCFH values). The mean PM2.5 concentrations in both urban environments were above the recommended daily value, and the dominant PM2.5 mass contributor was organic matter (29-55%). The OC/EC ratio was significantly higher at UB site during winter, which was an indication of a considerable contribution of secondary organic carbon to the overall organic carbon (OC). Water-soluble organic carbon (WSOC) was also higher at UB than at UI site, and it probably came from the same sources as OC. In general, the different partition of secondary organic aerosol (SOA) in warm and cold periods affected the number of organic components. Sulfates and nitrates were the most abundant ions at both sites and they counted approximately 40% (summer) and 50% (winter) of total ions. Further, the concentrations of the most elements, particularly some potentially carcinogenic elements such as As, Cd and Pb were significantly higher at UI, due to the emissions from the copper smelter complex in the vicinity. The mean OPDCFH values were similar during the summer at both sampling sites, whereas a statistically significant difference between sites was noticed in favor of UB environment in winter.

Environmental impact of industrial and agricultural activities to the trace element content in soil of Srem (Serbia).

This study reports the contents and sources of Cu, Hg, Cr, Ni, Co, Zn, Pb, Cd, As, and B pollution in soil samples from Srem in the province of Vojvodina (Republic of Serbia). They are collected in the vicinity of local industrial facilities. The main objective of this study is evaluating the impact of the industrial facilities on the eventual contamination of soils used mostly for agricultural manufacturing. This paper describes the implementation of the combination of methods to estimate the ecological status and determine potential ecological risk. This study applies sequential extraction, pollution indices, comparison with the guidelines, and statistical analysis. Other soil parameters, such as organic matter content, pH, and clay content were measured to evaluate their influence on the trace element content. The investigated soil samples exhibited the raised contents of Ni, Hg, and Cu. Elevated contents of toxic elements observed in localities accommodated within an impact zone affected by industrial complexes, indicating a correlation between the contamination of surrounding soil and potential impact on plants. The most mobile elements are Hg, Cd, and B, while Cr is the least mobile and potential least bioavailable. The results indicate Cr and Ni content increase marking the presence of bedrock, notably in the area of underlying ultramafic rocks and the surface zones influenced by diluvial-proluvial and alluvial processes. The second source of Cr and Ni in the soils of Srem is industrial activities such as leather, cement industry, as well as the metal processing factory.

Assessment of airborne heavy metal pollution using plant parts and topsoil.

Robinia pseudoacacia L. (Fabaceae) was evaluated as a possible bioindicator of airborne heavy metal pollution, which originates from mining and pyrometallurgical copper production in Bor (Eastern Serbia). Concentrations of Cu, Zn, Pb, Cd, As and Hg were determined in different plant organs (washed/unwashed leaves, branches, roots) and topsoil of R. pseudoacacia by ICP-AES and by AAS. Sampling was carried out during 2008 at ten selected sites distributed in five zones with different levels of pollution. Concentrations of Pb, Cd and Hg did not exceeded the maximum allowed concentration (MAC) in soils at any of the sampling sites. Cu and As were present only at two sites within the MAC, whereas Zn exceeded the MAC at two sampling sites. Although present in the soil, As, Cd and Hg were below limit of detection in all parts of R. pseudoacacia. The rest of the studied elements, collected at the sites closest to the copper smelter or in the directions of the prevailing winds, were found to be at high levels. The higest Cu and Zn concentrations were detected in branches of R. pseudoacacia at the site Krivelj in the rural zone (6418.2±355.4 mg kg⁻¹ and 4699.8±320.8 mg kg⁻¹, respectively). Pb was present in similar amounts in all parts of R. pseudoacacia in the concentration ranging from 4.9 ± 0.3 mg kg⁻¹ (in washed leaves, at tourist zone) to 66.9±5.3 mg kg⁻¹ (in roots, at urban-industrial zone). According to the mobility ratio, leaves and branches of R. pseudoacacia acted as excluders of Cu, Zn and Pb, except for the branches which acted as indicators of Zn. Although As is present in high concentrations in the air and topsoil of the examined area, results show that R. pseudoacacia is not a suitable indicator of environmental pollution with As.

Multi-criteria Analysis of Air Pollution with SO(2) and PM(10) in Urban Area Around the Copper Smelter in Bor, Serbia.

This work presents the results of 4 years long monitoring of concentrations of SO(2) gas and PM(10) in the urban area around the copper smelter in Bor. The contents of heavy metals Pb, Cd, Cu, Ni, and As in PM(10) were determined and obtained values were compared to the limit values provided in EU Directives. Manifold excess concentrations of all the components in the atmosphere of the urban area of the townsite Bor were registered. Through application of a multi-criteria analysis by using PROMETHEE/GAIA method, the zones were ranked according to the level of pollution.