Manisha Thakur

Assessment of Atmospheric Arsenic Level in Airborne Dust Particulates of an Urban City of Central India

An assessment of arsenic contamination in Raipur city (21°14′N, 18°38′E) of Chhattisgarh in the central part of India is reported here, for a monitoring period between November 1996 to June 1997, in airborne dust particulates. The concentration level of As were higher in the industrial site, followed by heavy traffic as compared to other sites. The monthly atmospheric arsenic deposition, in μg As per g of dust fall, of 6 sites are in the range of 0.100(μ0.020)–4.00(μ0.020); site no. 1 industrial area, 0.100(μ0.020)–0.320(μ0.020); site no. 2 residential area, 0.044(μ0.070)–0.337(μ0.030); site no. 3 commercial area, 0.093(μ0.068)–1.870(μ0.020); site no. 4 residential area, 0.111(μ0.020)–1.912(μ0.010); site no. 5 residential area and 0.068(μ0.040)–3.037(μ0.060); site no. 6 heavy traffic area. The total annual flux of As in the fall-out at different zones is in the range 0.033–1.12 kg km-2 yr-1. The month wise collection and analysis of dust fall out rate between 3.0(μ0.10)–91.3(μ1.4) mt (metric tonnes) km-2 month-1 were observed at all 6 sampling sites. Anthropogenic and environmental factors play important roles in the contribution of arsenic in airborne particulate matters.

Spectrophotometric determination of lead with N-hydroxy-N, N'-diphenylbenzamidine and diphenylcarbazone in airborne dust particulates and soil

A simple, selective and sensitive method for the spectrophotometric determination of lead in airborne dust particulate and soil samples is described. The method is based on the selective extraction of lead at pH 10.0 ± 0.2 with N-hydroxy-N,N′-diphenylbenzamidine (HDPBA). The yellow PbII–HDPBA complex shows maximum absorbance at 410 nm with a molar absorptivity of 1.6 × 104 l mol–1 cm–1. The sensitivity of the method is further increased by the addition of a methanolic solution of diphenylcarbazone (DPCZO) to the extract. The pink PbII–HDPBA/DPCZO complex has a molar absorptivity of 7.2 × 104 l mol–1 cm–1 at λmax = 525 nm. The detection limit of the method is 4 ng ml–1 in the organic phase and the Sandell’s sensitivity of the method is 0.0015 µg cm–2. The relative standard deviation for 10 replicate measurements of Pb at a level of 1.0 µg ml–1 is 1.5%. The method has been successfully applied to the determination of PbII in airborne dust particulates and soil samples.

Lead Levels in the Airborne Dust Particulates of an Urban City of Central India

The dust fall-out rate, distribution pattern andconcentration of lead in the particulate fall-outmatters in urban Raipur city covering an area of 160 km2 during one hydrological year i.e. November1996–June 1997, has been described. The entire cityhas been divided into 6 zones comprising ofindustrial, commercial, residential and heavy trafficareas. A monthly collection and analysis of dustfall-out rate between 3.0(±0.1) and91.3(±1.2) metric tonnes km-2 month-1 wereobserved at all 6 sampling sites. The total annualflux of lead in the fall-out of the city at differentzones is in the range 0.0065–0.4304 kg km-2yr-1. The results show that dust fall-out and thelead levels both are at higher magnitudes in winterand autumn. These large levels of air pollutants havealso been correlated with some meteorological parameters like relative humidity and temperature, and strong positive correlations have been observed.

Fractionation and spectrophotometric determination of thallium with N,N ′-diphenylbenzamidine, brilliant green and cetylpyridinium chloride

AbstractA spectrophotometric method for the determination of inorganic chemical species of thallium i.e.Tl(I), Tl(III) and total Tl at trace level in industrial waste waters, effluents and surface water of the city and neighbouring cities is described. The method is based on the extraction of chlorothallate(III) complex in the presence of cetylpyridinium chloride (CPC) at 0.5–4.5 M HCl with N,N’-diphenylbenzamidine (DPBA) in toluene and subsequent colour reaction of the extract with brilliant green (BG). The molar absorptivity of the Tl(III)-Cl−–CP+–DPBA–BG+ complex in toluene is 1.82x105 Lmol−1 cm−1 at 640 nm. The standard deviation and relative standard deviation of the method (n=10) were found to be 0.007 ppm Tl and 1.3% of the mean absorbance, respectively. The detection limit, defined as the concentration causing more absorbance than twice the standard deviation of 10 replicate measurements of the blank solutionis 5 μg L−1 Tl in water. For effluent samples the concentration ranges of Tl(I), Tl(III) a...