Characterization of aerosols and its radiative impacts over urban and rural environments--a case study from Hyderabad and Srisailam

In the troposphere anthropogenic aerosol emissions are increasing in recent decades, which can influence the earth's climate. The present study addresses the characterization of aerosols and their radiative impacts over urban (Hyderabad) and rural (Srisailam) environments by using aerosol optical depth (AOD) measurements from MICROTOPS-II sunphotometer. AOD measurements over the urban site showed high values compared to the rural site. Over the urban environment aerosol forcing at the surface is as high as -42 W m(-2) and at the top of the atmosphere (TOA) is +10 W m(-2) whereas at the rural environment aerosol forcing at the surface has been observed to be -11 W m(-2) and at TOA it is observed to be +5.7 W m(-2). The difference between TOA and the surface forcing over the urban environment is +32 W m(-2) and over the rural environment is +5.3 W m(-2), which shows the absorption capacity of the respective atmospheres.     

Volatile metabolites from mold growth on building materials and synthetic media

Mold species which were isolated from damp buildings were grown on sterile building materials and some synthetic media in order to study the microbial volatile organic compounds produced. Patterns of the microbial volatile organic compounds (MVOC) were very media dependent but media which favor terpene biosynthesis may give patterns unique enough for identification of dominant indoor molds.     

Effect of nitrogenous air pollutants on changes in protein spectra with the onset of winter in the leaves and shoots of the bilberry (Vaccinium myrtillus L.)

Electrophoretic profiles of 0.1 m Tris-HCl (pH 9.0)-soluble proteins in the leaves and stems of the bilberry (Vaccinium myrtillus L.) were investigated in the latter part of the growing season (July-October), in a highly-polluted industrial area with serious forest damage (main emissions NO(2), SO(2), NH(3), urea and fertilizer dust) in Oulu, northern Finland, and in an unpolluted control forest with the same climatic and edaphic conditions. About ten protein components in the leaves and seven in the stems increased in concentration in SDS-PAGE towards the autumn, while one to four other components decreased in concentration. The pollutants in the industrial area caused a considerable decrease in the concentrations of soluble proteins, particularly in the leaves in August and September. A decrease was obtained in six components in the leaves and three components in the stems, while increases were observed in one component in the leaves (10 kDa) and four components in the stems (10, 43, 50 and 65 kDa). One reason for the lowered cold-resistance in the bilberry caused by air pollutants could thus be the lowered concentrations of certain soluble cytoplasmic proteins that protect the plant against winter conditions.     

Response of spinach and kidney bean plants to nitrogen dioxide

Different responses of spinach and kidney bean plants to various concentrations of NO(2) in the light and in the dark were shown. Spinach is more resistant than NO(2) than kidney bean. It is not only due to its greater tolerance to NO(2)(-) accumulated in leaves, but also to its stronger ability to metabolize NO(2)(-). The injury of spinach induced by the exposure to high concentration NO(2) in the light was not caused by the accumulation of NO(2)(-), but concerned the large amount of accumulated NH(3). The primary causes of NH(3) accumulation were that the activity of nitrite reductase was not affected by the fumigation on the one hand, and the activities of glutamine synthetase and glutamate synthase were inhibited on the other.     

Butyltins in muscle and liver of fish collected from certain Asian and Oceanian countries

Concentrations of butyltin residues were determined in muscle tissue of fish collected from local markets and sea food shops in India, Bangladesh, Thailand, Indonesia, Vietnam, Taiwan, Australia, Papua New Guinea and the Solomon Islands. Contamination levels were determined in the Asia-Pacific region and human exposure was estimated. Similarly, corresponding liver samples of fish muscle collected in Australia, Papua New Guinea and the Solomon Islands were analyzed to obtain information on partitioning of butyltin compounds between muscle and liver tissues. Butyltin compounds were detected in most of the samples which suggested widespread contamination in Asia and Oceania. The concentrations of butyltin compounds were, on average, an order of magnitude higher in liver than in muscle. Residue concentration of Sigmabutyltin in liver was found to be correlated significantly (p < 0.02) with those in muscle. Intensive ship-scrapping activities, sewage disposal and antifouling paints are considered the major sources of butyltins in this region. Increased proportions of MBT over DBT and TBT in samples from most locations indicated degradation of TBT to MBT in fish tissues during storage at 4 degrees C in the dark over 1-2 years. The possibility that fish have been subject to increased exposure to MBT and that TBT degrades to MBT quite rapidly in tropical environments are also considered. Butyltin concentrations in fish from Asia and Oceania were lower than those reported for Japan, Canada and the USA. Although the number of samples analyzed from each country was small, it is tentatively suggested that intake of butyltins by humans via consumption of fish in these countries was < 25% of the tolerable daily intake of 250 ng kg bw(-1) day(-1). To our knowledge, this is the first study reporting on butyltin pollution in developing Asian countries.     

Simulation of dioxin accumulation in human tissues and analysis of reproductive risk

Polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran and dioxin-like polychlorinated biphenyl concentrations in human liver, kidney, fat, blood, muscle, richly perfused tissue (brain, lung etc.) and skin were simulated to assess the health risk for Japanese fetuses. A 40-year time course of dioxin accumulation via food ingestion was simulated using a physiologically based pharmacokinetic (PBPK) model. In richly perfused tissue, the concentration estimated by the PBPK model showed better agreement with measured concentrations than that calculated by the one-compartment model. Fetal dioxin concentration was simulated based on the assumption that the fetal concentration was almost equal to the concentration in the mother's richly perfused tissue. To assess the reproductive risk, the estimated concentration in human fetus was compared with that in rat fetus in which reproductive function showed signs of alteration by 2,3,7,8-TCDD in previous reports [Toxicol. Appl. Pharmacol. 114 (1992) 118; 146 (1997) 11; Toxicol. Sci. 53 (2000) 411; 57 (2000) 275]. The present daily intake of 2,3,7,8-TCDD is approximately 1/50 of the amount that leads to possible reproductive toxicity in the next generation. However, when 29 kinds of dioxin congeners are considered, the present level is 1/5 of the hazardous levels. For species extrapolation of dioxin risk, further study on tissue concentration versus toxicity is required.     

Removal characteristics of trace compounds of landfill gas by activated carbon adsorption

The removal characteristics of trace compounds and moisture in raw landfill gas (LFG) were studied. The LFG from the extraction well was saturated with water and moisture was eliminated by physical methods including cyclone-type dehydrator and compressor. The moisture removal efficiency of dehydrator and compressor was above 80%. As the moisture contents of LFG decreased, the toxic compounds like aromatics and chlorinated compounds were effectively removed by using the granular activated carbon. The breakthrough time and adsorption capacity of benzene, toluene, and ethyl benzene decreased rapidly when the relative humidity is over 60%. The effect of moisture was more pronounced at lower adsorbate concentrations tested than at higher concentrations. The breakthrough curves for multi-component mixtures show displacement effects. In the course of competing adsorption, adsorbates with strong interaction force to displace weakly bounded substances. Adsorption by activated carbon is in descending order of xylene, ethylbenzene, toluene, tri or tetrachloroethylene, benzene, carbon tetrachloride and chloroform in LFG, respectively.     

Levels and pattern of volatile organic nitrates and halocarbons in the air at Neumayer Station (70 degrees S), Antarctic

Levels and patterns of C1-C4/C9 organic nitrates were measured for the first time in Antarctica. The sampling was done by adsorptive enrichment on Tenax TA followed by thermodesorption cold-trap high resolution capillary gas chromatography with electron capture detection. 2-70 1 air on-column have been analyzed this way. C1-C9 alkyl mononitrates, C2-C4 alkyl dinitrates, C2-C4 hydroxy alkyl nitrates, and halocarbons could be identified in air samples collected near the German Neumayer Research Station, Antarctica, in February 1999. Volatile biogenic and anthropogenic halocarbons were used to assess the origin of the air parcels analyzed. The average concentration measured for sigmaC2-C6 alkyl nitrates was in the range of 9.2 +/- 1.8 ppt(v), while the sum of the mixing ratios of six C2-C4 hydroxy alkyl nitrates was in the range of 1.1 +/- 0.2 ppt(v). Moreover, C2-C4 alkyl dinitrates were found at levels near the detection limit of 0.1-0.5 ppt(v). The concentrations of organic nitrates found in Antarctic air represent ultimate baseline levels due to chemical and physical loss processes during long-range transport in the air. The South Atlantic and the Antarctic Ocean as a general secondary source for organic nitrates in terms of an air/sea exchange equilibrium has to be evaluated yet, but it seems logical. Our results confirm the common assumption that there are no biogenic marine sources of C2-C9 organonitrates. We have found a level of > 80 ppt(v) for methyl nitrate. This level if it can be confirmed in a systematic survey requires a strong biogenic source of methyl nitrate in the Antarctic Ocean.