Temporal and spatial variations of PM2.5 organic and elemental carbon in Central India

Environmental Geochemistry and Health - This study describes spatiotemporal patterns from October 2015 to September 2016 for PM2.5 mass and carbon measurements in rural (Kosmarra), urban (Raipur),...     

Thermodynamic analysis of in situ gasification-chemical looping combustion (<Emphasis Type="Italic">i</Emphasis>G-CLC) of Indian coal

Chemical looping combustion (CLC) is an inherent CO₂ capture technology. It is gaining much interest in recent years mainly because of its potential in addressing climate change problems associated with CO₂ emissions from power plants. A typical chemical looping combustion unit consists of two reactors—fuel reactor, where oxidation of fuel occurs with the help of oxygen available in the form of metal oxides and, air reactor, where the reduced metal oxides are regenerated by the inflow of air. These oxides are then sent back to the fuel reactor and the cycle continues. The product gas from the fuel reactor contains a concentrated stream of CO₂ which can be readily stored in various forms or used for any other applications. This unique feature of inherent CO₂ capture makes the technology more promising to combat the global climate changes. Various types of CLC units have been discussed in literature depending on the type of fuel burnt. For solid fuel combustion three main varieties of CLC units exist namely: syngas CLC, in situ gasification-CLC (iG-CLC) and chemical looping with oxygen uncoupling (CLOU). In this paper, theoretical studies on the iG-CLC unit burning Indian coal are presented. Gibbs free energy minimization technique is employed to determine the composition of flue gas and oxygen carrier of an iG-CLC unit using Fe₂O₃, CuO, and mixed carrier—Fe₂O₃ and CuO as oxygen carriers. The effect of temperature, suitability of oxygen carriers, and oxygen carrier circulation rate on the performance of a CLC unit for Indian coal are studied and presented. These results are analyzed in order to foresee the operating conditions at which economic and smooth operation of the unit is expected.     

Trace elements and organochlorine pollutants in selected fish species from Lake Phewa,Nepal

Lake water and fish livers and gills of sahar (Tor putitora), spiny eel (Mastacembelus armatus), African magur (Clarias gariepinus), and tilapia (Oreochromis niloticus) from Lake Phewa, Nepal, were assessed for the concentrations of trace metals/elements and persistent organic pollutants. The lake water was neutral with low ionic and metallic concentrations as compared to high-altitude lakes of Nepal. The four elements Cu, Zn, Se, and Cd had highest concentrations in livers, indicating uptake from diet, whereas four other metallic elements Cr, Mn, Ni, and Pb had highest concentrations in gills, indicating uptake from lake water. O. niloticus tended to have most of trace metals in the liver at higher concentrations than the other species but significant differences among the different species were found only for Mn, Ni, and Zn in the gills. A pilot study on the concentrations of persistent organic pollutants in muscle revealed that dichlorodiphenyltrichloroethane and related compounds were the dominant organochlorine pesticides, having highest concentrations in C. gariepinus and lowest in O. niloticus.     

Integration of traditional and innovative characterization techniques for flux-based assessment of Dense Non-aqueous Phase Liquid (DNAPL) sites

Key attributes of the source zone and the expanding dissolved plume at a trichloroethene (TCE) site in Australia were evaluated using trends in groundwater monitoring data along with data from on-line volatile organic compound (VOC) samplers and passive flux meters (PFMs) deployed in selected wells. These data indicate that: (1) residual TCE source mass in the saturated zone, estimated using two innovative techniques, is small ( 10 kg), which is also reflected in small source mass discharge ( 3 g/day); (2) the plume is disconnecting, based on TCE concentration contours and TCE fluxes in wells along a longitudinal transect; (3) there is minimal biodegradation, based on TCE mass discharge of  6 g/day at a plume control plane  175 m from source, which is also consistent with aerobic geochemical conditions observed in the plume; and (4) residual TCE in the vadose zone provides episodic inputs of TCE mass to the plume during infiltration/recharge events. TCE flux data also suggest that the small residual TCE source mass is present in the low-permeability zones, thus making source treatment difficult. Our analysis, based on a synthesis of the archived data and new data, suggests that source treatment is unwarranted, and that containment of the large TCE plume ( 1.2 km long,  0.3 km wide; 17 m deep;  2000–2500 kg TCE mass) or institutional controls, along with a long-term flux monitoring program, might be necessary. The flux-based site management approach outlined in this paper provides a novel way of looking beyond the complexities of groundwater contamination in heterogeneous domains, to make intelligent and informed site decisions based on strategic measurement of the appropriate metrics.     

Second trimester diagnosis of Neu Laxova syndrome

This is the first report of a prenatally diagnosed case of Neu Laxova syndrome (NLS) from India. This also includes a case of NLS in monochorionic diamniotic twins and two more cases in which we were able to detect most of the features of NLS as early as 19 to 20 weeks by routine antenatal ultrasonography. Severe intrauterine growth retardation (IUGR), microcephaly, central nervous system (CNS) abnormality, joint contractures, and abnormal facies are the major diagnostic features observed in prenatal ultrasonography. Risk factors such as consanguinity and history of intrauterine death or stillbirth in siblings have been noted in all the cases, but none of the three families that were reported had previously had an affected fetus. The spectrum of skin manifestations and frequency of occurrence of major clinical features of the syndrome have been discussed. Review of the literature on NLS and possibility of detecting the syndrome in the second trimester is discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

Heterogeneous oxidation by ozone of naphthalene adsorbed at the air-water interface of micron-size water droplets

The mass transfer of naphthalene vapor to water droplets in air was studied in the presence of ozone (O3) in the gas phase. A falling droplet reactor with water droplets of diameters 55, 91, and 182 microm was used for the study. O3 reacted with naphthalene at the air-water interface, thereby decreasing the mass transfer resistance and increasing the rate of uptake of naphthalene into the droplet. A Langmuir-Hinshelwood reaction mechanism at the air-water interface satisfactorily described the surface reaction. The first-order surface reaction rate constant, ks, increased with decreasing droplet size. Three organic intermediates were identified in the aqueous phase as a result of ozonation of naphthalene at the surface of the droplet indicating both peroxidic and nonperoxidic routes for ozonation. The presence of an organic carbon surrogate (fulvic acid) increased both the partition constant of naphthalene and the surface reaction rate of O3. The heterogeneous oxidation of naphthalene by O3 on the droplet was 15 times faster than the homogeneous oxidation by O3 in the bulk air phase, whereas it was only 0.08 times the homogeneous gas-phase oxidation by hydroxyl radicals under atmospheric conditions.     

An improved product-process for cleaner chrome tanning in leather processing

Severe restrictions imposed by the pollution control authorities on the disposal of chromium, total dissolved solids and chlorides in tannery effluents have forced the tanners to look for low-waste, high exhaust chrome tanning salts. An improved chrome syntan with more than 90% uptake of chrome has been developed. The new product serves both as tanning and retanning agent and can be applied directly to delimed pelts thus eliminating the conventional pickling stage in the leather processing. This modified process helps to reduce the chemical oxygen demand (COD), total dissolved solids (TDS) and chlorides in the spent tan liquor by 51, 81 and 99%, respectively. The product offers full, soft leathers having shrinkage temperature comparable to conventional chrome tanned skins. Since the developed product is highly reactive, it saves time and reduces the water requirement when compared to the conventional chrome tanning method. Thus the novel product/process developed not only has advantages in reducing pollution loads but also seems to be techno-economically viable.     

Characterization of airborne particles at a high-btu coal-gasification pilot plant

Airborne particles in fugitive emissions have been measured at a slagging fixed-bed coal-gasification pilot plant using lignite. Sampling was conducted during shutdown operations and opening of the gasifier following an aborted startup. Aerosol collected with a Sierra high-volume impactor was subjected to analysis by gas chromatography, mass spectrometry, and scanning electron microscopy; aerosol collected with an Andersen low-volume impactor was subjected to flameless atomic absorption analysis. The data show that the bulk of the trace organic material is associated with small particles: these data are similar to data on ambient air reported in the literature. Particle morphologies resemble those of fly ash from coal combustion, including smooth spheres, vesicular spheres, and crystalline material. Trace element size distributions are bimodal and resemble data for ambient air. Pb-containing particles are generally submicron, while particles containing Al, Fe, and other crustal species are mostly of supermicron size. Aluminum-based aerosol enrichment factors calculated from the lignite composition show that the composition of the aerosol resembles that of the coal, with the exception of modest enrichments of Mg, Na, As, and Pb in the submicron size range. Aerosol enrichment factors based on the earth's crustal composition are somewhat greater than those based on coal composition for several elements, suggesting potential errors in using crustal enrichment data to investigate chemical fractionation during aerosol formation.     

Characterization of airborne trace metal and trace organic species from coal gasification

Fugitive emissions from a slagging fixed-bed coal-gasification pilot plant were analyzed by flameless atomic absorption spectrophotometry, gas chromatography, and mass spectrometry for trace metal and trace organic species. Analysis of the size distributions of airborne particulate matter inside the plant showed an abundance of large metal-containing particles; outdoor distributions in the vicinity of the plant resembled the indoor distributions, suggesting the importance of the gasifier in influencing ambient air quality. This conclusion was further supported by identification of similar organic compounds inside and outside the plant. Trace element enrichment factors based on the earth's crustal composition were greater than those based on the composition of the lignite used in the gasifier, showing the importance of characterizing the proper source material when inverstigating chemical fraction during aerosol formation. Enrichments in the present study were much greater than those found in previous sampling during aborted start-up and cleaning procedures, where normal operating temperatures had not yet been reached. Both studies showed evidence of enrichment factors which decreased with increasing particle size. Although much of the airborne mass was associated with large particles having low respirability, the high concentrations of some metals indoors suggests that further assessment of potential occupational exposures is warranted.     

A comparative study on the toxic effects of textile dye wastewaters (untreated and treated) on mortality and RBC of a freshwater fish Gambusia affinis (Baird and Gerard)

Comparative toxicological studies of textile dye wastewater (untreated and treated) on a freshwater fish, Gambusia affinis, revealed a marked reduction in mortality and cytotoxic effects on RBCs, measured as reduction in their counts and percent changes in their shape (poikilocytosis) and variation in their size (anisocytosis)}, after subjecting them to both physicochemical and biological treatments. On comparing the data of mortality and the cytotoxic effects on RBCs, we found poikilocytosis is a better indicator for toxicity measurement of both untreated as well as treated wastewater, especially at their lowest concentrations where percent mortality was found to be either nil or lowerer than the percentage of poikilocytic RBCs. Although percent reduction in RBC counts and changes in their size (anisocytosis) indicated toxic effects of wastewaters, but EC5o values for RBC counts were usually higher than those for poikilocytosis and mortality, and non-calculable for anisocytosis suggesting their lesser sensitivity to pollutants. In view of these findings, we recommend monitoring of toxic effects of wastewaters during fish bioassay on both mortality and variation in RBC shape.