K. Maharaj Kumari

HCHO, HCOOH and CH3COOH in air and rain water at a rural tropical site in North Central India

HCHO, HCOOH and CH3COOH were measured in vapour phase and rain water during monsoon period at Gopalpura, Agra a rural site of north central semi-arid tract of India. Mean concentrations of formaldehyde, formic and acetic acids were 1.4, 1.7 and 1.6 ppbv in the vapour phase and were 4.4, 5.4 and 4.8 μmol l−1 (volume weighted) in rain water, respectively. Due to cloud cover and rain which occurs intermittently in monsoon these species did not show typical diurnal pattern as reported by others. In the gas phase a good correlation of formic acid with acetic acid (r = 0.78) and poor correlation with formaldehyde (r = 0.19) suggested that formic and acetic acids may also have significant contributions from other than photochemical sources such as biogenic sources. The strong correlation between formate and acetate (r = 0.96) and formate and formaldehyde (r = 0.95) in rain water suggests that their sources are common, if not identical. Regression analysis between concentration vs precipitation volume and deposition amount vs precipitation volume of the three species suggested that concentration of these species are almost independent of rain volume and controlled by a continuous supply of these species by slowly scavenged material or oxidation of aldehyde to organic acid. HCOO−/HCHO ratio (1.4) also suggested that aqueous-phase oxidation of formaldehyde is a major source of formic acid in rain water.

A Long Term Study on Chemical Composition of Rainwater at Dayalbagh, a Suburban Site of Semiarid Region

Rainwater samples were collected for the monsoon period of 1988 and 1991–1996 at Dayalbagh (Agra), a suburban site situated in semiaridregion. The mean pH was 7.01 ±1.03 well above 5.6, which is the reference pH. Concentration of Ca2+ was observed to be highest followed by Mg2+, NH4+,SO42−, Cl−,NO3−, Na+, F− and K+. The ratios of SO42− + NO3− andCa2+ + Mg2+ (TA/TC) have been considered as indicatorfor acidity. In the Agra region ratio of TA/TC is quite below 1.0 indicating alkaline nature of rainwater. The lowest value of 0.24 was observed in 1991 likely due to the lowest rain depth of the decade. The highest value of 0.54 was observed in 1996, a year with a large rain depth and increase in line (vehicular traffic) and area sources (population growth). Good correlation between Ca2+ and NO3−,Ca2+ and SO42− andSO42− and NO3−,indicates that wind carried dust and soil play a significant role in neutralization of precipitation acidity.

Multiphase measurement of atmospheric ammonia

Abstract Measurement of ammonia in vapour phase, particulate and rain was made at a suburban site of India. Vapour phase concentrations varied between 0.97 and 25.5 μg m−3 (57.1–1500.0 nmol m−3) and diurnal variation study showed high concentration of NH3 during night time and minimum at 0600 h (early morning). Particulate phase NH4 values ranged between 1.2 and 5.3 μg m−3 (66.7–294.4 nmol m−3). Dry deposition flux was determined from model calculations. Day time NH3 flux was found to be 8.4±4.0 mg m−2 d−1 and that of night 2.2±1.2 mg m−2 d−1. With respect to particulate deposition flux was found 0.2±0.1 mg m−2 d−1 while in precipitation values of NH4 ranged between 0.7 and 74.4 μeq l−1. Regression analysis of ammonium concentration with rain volume and deposition indicates that NH3 concentration is being controlled by both gas and particulate ammonium. Annual inputs for wet and dry deposition were found to be 0.34±0.3 and 3.9±1.9 g m−2 y−1.

Rainwater Composition at a Regional Representative Site of a Semi-Arid Region of India

Rainwater samples (N = 51) were collected at Rampur, an areafree from anthropogenic activity during the monsoon of 1997 and1998. The concentration of ions follows a general pattern as Ca> NH4 > Mg > SO4 > Cl > F >Na > NO3 > K > HCOO >CH3 COO. The pH of precipitation ranges between 5.9 and 7.4. The levels of Ca and Mg at this site are higher than otherremote sites, probably dominated by particles of soil origin.Good correlation between Ca, NO3, SO4, HCOO and CH3COO indicate that a fraction of NO3, SO4, HCOOand CH3COO may be derived from soil or associated with Ca and Mg after neutralization. The order of neutralization factorCa (2.19) > NH4 (1.26) = Mg (1.26) indicates that majorneutralization occurred by Ca. Factor analysis suggested thatCa, Mg, Na, K, NO3, SO4, HCOO and CH3COO arecontributed by soil. NH3 is known to exist as(NH4)2SO4, NH4NO3 and NH4Cl. Theymay be formed in the atmospheric water droplets by scavenging ofaerosols and reaction of gaseous species.

Comparison of BTX Profiles and Their Mutagenicity Assessment at Two Sites of Agra, India

In the present study, the concentrations of three volatile organic compounds (VOCs), namely, acronym for benzene, toluene, and xylenes (BTX) were assessed because of their role in the tropospheric chemistry. Two representative sites, a roadside and a petrol pump, were chosen for sample collection. VOCs were collected using SKC-activated charcoal tubes and SKC personal sampler and characterized by gas chromatograph using flame ionization detector. Among BTX, benzene had the highest concentration. At the roadside, mean concentration of benzene, toluene, o-,m-xylene, and p-xylene were 14.7 ± 2.4 μgm−3, 8.1 ± 1.2 μgm−3, 2.1 ± 0.8 μgm−3, and 5.1 ± 1.2 μgm−3, respectively. At the petrol pump, the mean concentrations of benzene, toluene, o-,m-xylene and p-xylene were 19.5 ± 3.7 μgm−3, 12.9 ± 1.1 μgm−3, 3.6 ± 0.5 μgm−3 and 11.1 ± 1.5 μgm−3, respectively, and were numerically higher by a fraction of 2. Monthly variation of BTX showed maximum concentration in winter. Inter-species ratios and inter-species correlation indicated traffic as the major source of BTX. Extracts of samples were positive in both Salmonella typhimurium tester strains TA98 and TA100 without metabolic activation suggesting the presence of direct mutagens in ambient air that can cause both frame-shift and base-pair mutation. The mutagenic response was greater for TA100 than TA98 suggesting greater activity for base-pair mutagenicity than frame-shift mutagenicity and was found to be statistically significant.

Formate and acetate in particulate matter and dust fall at Dayalbagh, Agra (India)

Formate and acetate were estimated in particulate matter and dust fall at Dayalbagh. The mean concentration of formate and acetate in particulate matter was 290±-205 and 320±-90 ng m−3 in the winter and 240±-160 and 440±-100 ng m−3 in the summer. The percent of formic acid present in the particulate phase was 29% in the winter and 25% during the summer while the same values for acetic acid were 29% and 43%, respectively. Higher percentages of both acids in particulate phase compared to those observed at other sites were attributed to the basic nature of aerosol at this site. In dust fall, the fluxes of formate in the winter and summer were 132±-114 and 155±-55 μg m−2 day−1, respectively while corresponding acetate fluxes were 177±-166 and 80±-54 μg m−2 day−1. Higher fluxes at this site is contributed by higher atmospheric loading of particulate matter, dominated by the soil-derived elements. The estimated deposition velocities of particulate formate were 0.5±-0.6 cm s` in winter and 0.3±-0.6 cm s−1 in summer while vd′s for particulate acetate were 1.0±0.9 cm s−1 in winter and 0.5±-0.6 cm s−1 in summer.

Characterization and Mutagenicity Assessment of PM2.5 and PM10 PAH at Agra, India

Fine airborne particulate matter and bound chemical compounds are potential mediators of adverse health effects. In this study, PM2.5 and PM10 were characterized for bound polycyclic aromatic hydrocarbons (PAHs) and the mutagenic potential of extracts was assessed. PM2.5 and PM10 samples were collected on glass fiber filters at Agra from July to December 2010 using a fine particulate sampler (Envirotech, APM 550). The content of PAH was analyzed by gas chromatography and the extract were tested for mutagenicity by the Ames test without using S9. Individual PAH concentration varied from 13–172 ng m−3 with concentration for Chrysene and a dominance of low molecular weight compounds. Both PM and PAH concentrations were higher in the winter and were negatively correlated with temperature and wind speed. Diagnostic ratio analysis indicated contributions from vehicular exhaust and emissions from combustion of domestic fuel like coal and wood. Mutagenicity assays indicated the presence of mutagens capable of causing base pair and frame shift mutagenicity; however, within the range of tested concentrations no significant toxic effects were detected.

Characterization of organic acids in dew collected on surrogate surfaces

Levels of formate and acetate in dew were measured at Dayalbagh, India, usingsurrogate surfaces. The dew formed per night ranged between 0.06 lm−2 and 1.38 l m−2, with an average of 0.59l m−2. pH ranged between 6.7 and 7.4. Mean concentrations offormate and acetate in dew were 10.2 ± 10.2 μeql−1 and 7.5 ± 4.5 μeq l−1,respectively. The correlation coefficient between the two ions was 0.80 (p =0.001), which suggested that concentrations of these species in dew are linkedtogether. They have either common or different sources with fairly constantstrengths or products of same reaction. Good correlation of formate andacetate with Ca (r = 0.82 and r = 0.70, respectively) and Mg (r = 0.74 and r= 0.71, respectively) suggested that these ions may be associated with Ca andMg after the neutralization process. Deposition rates for formate and acetatein dew per night were 10.2 ± 7.22 μmol m−2 pernight and 4.6 ± 2.2 μmol m−2 per night,respectively. The theoretical Henrys law constant (K*H)and the field-observed Henrys law coefficient (K*H) ascalculated from concurrent measurements of gas phase and dew for both acidsshowed large discrepancies of three orders of magnitude.

Chemical characteristics and mutagenic activity of PM2.5 at a site in the Indo-Gangetic plain, India

Airborne fine particulate matter PM2.5 was collected from May 2010 to December 2012 at Agra, a semi-urban site in north-central India. PM2.5 samples were chemically characterized for 16 polycyclic aromatic hydrocarbons by gas chromatography. PM2.5 values varied between 8.4 and 300 µg m(-3) with 55% of the values exceeding the 24h average NAAQ (National Ambient Air Quality) standard of 65 µg m(-3). Particle associated total PAHs ranged between 8.9 and 2,065 ng m(-3) with a mean value of 880.8 ng m(-3) during the sampling period, indicated an alarming level of pollution in Agra. Strong relationship was observed between PM2.5 and total PAHs (r=0.88), suggesting an increasing PAHs concentration with increasing PM2.5 mass. On a mass basis 3-ring and 4-ring compounds were dominant. Seasonal variation in mass concentration of PAHs was observed with high concentration in winter followed by post monsoon, summer and monsoon. This seasonal pattern could be attributed to differences in source strength and climatic conditions. PAHs concentration were also observed to be negatively correlated with the meteorological parameters i.e. temperature, solar radiation, relative humidity and wind speed. Molecular diagnostic ratios revealed vehicular emissions and combustion of wood and coal as the probable sources. The estimated carcinogenicity of PAHs in terms of benzo(a)pyrene toxic equivalency (B[a]PTEQ) was assessed and confirmed that benzo[a]pyrene was the dominant PAH contributor (3.64%). Health risk of adults and children by way of PAHs was assessed by estimating the lifetime average daily dose (LADD) and corresponding incremental lifetime cancer risk (ILCR) using USEPA guidelines. The assessed cancer risk (ILCR) was found to be within the acceptable range (10(-6)-10(-4)). The particulate samples indicated the presence of both base pair and frame shift mutagens using TA98 and TA100 strains of Salmonella typhimurium. Enhanced mutagenic response was observed in the presence of enzyme activation.

Surface ozone concentrations in Agra: links with the prevailing meteorological parameters

Measurements of surface ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), oxides of nitrogen (NOx=NO+NO2) and meteorological parameters have been made at Agra (North Central India, 27°10’N, 78°05’E) in post monsoon and winter season. The diurnal variation in O3 concentration shows daytime in situ photochemical production with diurnal maximum in noon hours ranging from 51 to 54 ppb in post monsoon and from 76 to 82 ppb in winter, while minimum (16–24 ppb) during nighttime and early morning hours. Average 8-h O3 concentration varied from 12.4 to 83.9 ppb. The relationship between meteorological parameters (solar radiation intensity, temperature, relative humidity, wind speed and wind direction) and surface O3 variability was studied using principal component analysis (PCA), multiple linear regression (MLR) and correlation analysis (CA). PCA and MLR of daily mean O3 concentrations on meteorological parameters explain up to 80 % of day to day ozone variability. Correlation with meteorology is strongly emphasized on days having strong solar radiation intensity and longer sunshine time.