Variations in Mass of the PM 10 , PM 2.5 and PM 1 during the Monsoon and the Winter at New Delhi

ABSTRACT PM 10 , PM 2.5 and PM 1 mass concentrations have been measured at Delhi (28°35'N; 77°12'E) during the August to December 2007. The running mean of PM 10 , PM 2.5 and PM 1 data shows large variations. The PM 10 , PM 2.5 and PM 1 were ranged from 20 to 180 g/m 3 during the monsoon and from 100 to 500 g/m 3 during the winter (up to 1200 g/m 3 in November due to Deepavali fireworks). For the same running mean cycles, higher mass concentrations in the PM 10 , PM 2.5 and PM 1 were corresponded with peaks in the relative humidity and lower levels linked to peaks in the ambient temperature. The evolutions of PM 10 , PM 2.5 and PM 1 concentrations after the elapsed times are simulated with mean mass scavenging coefficients. These evolution patterns clearly show the difference in washout of PM 10 with impaction scavenging relative to those for PM 2.5 and PM 1 particles over different rainfall durations. Air-mass pathways traced with HYSPLIT model over the study area illustrates the nature of PM 10 , PM 2.5 and PM 1 levels with monsoon and winter airmass circulations over Delhi

Chemical Characteristics of Water Soluble Components of Fine Particulate Matter, PM 2.5 , at Delhi, India

Abstract Aerosol samples in the size range up to 2.5µm were collected from January to December, 2005 at New Delhi, India, as a pilot experiment and analysed for organic (Oxalate and Formate) and inorganic (Sulfate, Ammonium, Nitrate, Potassium, Chloride, Sodium, Calcium and Magnesium) chemical components. Initial results show that the annual mean PM 2.5 concentration was 98.7µg/m 3 , which varied between 38 to 285µg/m 3 . The water soluble inorganic fraction constituted only 9% of PM 2.5 with SO 4 2-, NH 4 + and NO 3 -being the dominant ions followed by potassium. Annual cycle shows higher concentration of PM 2.5 during winter season (October to January) and the lowest during monsoon. It is attributed to the enhanced production of aerosols and prevailing meteorological conditions. The PM 2.5 /PM 10 ratio (0.86) coupled with the Hy SPLIT air-mass back trajectories indicated that PM 2.5 was dominated by fine particles, when the winds passed through the eastern azimuth, where many industries and major thermal power plants are located

Chemical composition of rainwater in Panipat, an industrial city in Haryana

443-449Chemical composition of rainwater at Panipat, an industrial city in India, during the south-west monsoon seasons 2003-2005 has been studied. The collected samples have been analyzed for major anions, cations and pH along with conductivity. The volume weighted pH of rainwater varied from 5.02 to 6.86 with a mean value of 5.51, which is slightly acidic. About 37% of rain samples were observed to be acidic due to high SO₂ emissions from industries. The trend of average ionic concentration in precipitation (μeq/l) showed SO₄²⁻> Ca²⁺> NH₄⁺> Cl⁻> NO₃⁻> Na⁺> Mg²+> F⁻> K⁺ >HCO₃⁻. The percentage contribution to the total ionic concentration is found to be 51% to cations and 49% to anions. Sulphate, calcium and ammonium shared maximum contribution. Major part of sulphate ion in rainwater at Panipat was of anthropogenic origin, i.e. by the oxidation of sulphur dioxide emitted from burning of fossil fuels from thermal power plant, oil refinery, fertilizer plant, etc. The major source of nitrate was biomass burning, automobile and soil. Ammonium in precipitation was due to bacterial action on nitrogen compounds in the soil, urine and from industrial sources. The ratio of sea salt (Na+ and Cl⁻) was equal to the seawater, suggesting that it was mostly influenced by marine air

Changes in Inorganic Chemical Species in Fog Water over Delhi

Abstract Heavy fogs occur during the winter period over the part of northern India and impact aviation, public transport, the economy, public life, etc. During winter, fog water (FW) and non-monsoonal rainwater (NMRW) samples were collected in Delhi, which is a highly polluted and populated megacity in northern India. The collected FW and NMRW samples were analyzed for their inorganic chemical constituents (F−, Cl−, SO42−, NO3−, NH4+, Na+, K+, Ca2+, and Mg2+). The volume-weighted mean (VWM) pH, conductivity, and total dissolved solids (TDS) of FW were 6.89, 206 μS cm−1, and 107 mg L−1, respectively, indicating the dominance of alkaline species. The total measured ionic constituents (TMIC) in FW and NMRW were 5,738 and 814 μeq L−1, respectively, indicating highly concentrated FW in Delhi. The TMIC in FW were factors of 16 and 7 times more concentrated than MRW and NMRW samples, respectively. The concentrations of inorganic acidic species (SO42− and NO3−) in FW were much higher than in monsoon rainwater (MRW: 3 and 5 times) and NMRW (8 and 12 times), respectively. Also, the concentrations of SO42− and NO3 in NMRW were approximately double compared to MRW indicating higher acidic species concentrations during the winter season over Delhi region. Significant decadal growth in the mean concentrations of ionic species in FW (SO42− - ~9 times; NH4+ - double) were observed between 1985 and 2010. However, the nitrate decreased by ~28%. The higher SO42− is likely from heavy-duty vehicles that burn sulfur-containing fuel. The anions in FW, MRW, and NMRW contributed 20, 42, and 43%. However, the cation contributions were 80, 58, and 57%, respectively. The anion contributions were lower in FW than MRW and NMRW indicating the weak formation of acidic species in fog water. The observed alkalinity suggests that it is unlikely for acid precipitation to be present in this region

Chemical characterization of PM2.5 and source apportionment of organic aerosol in New Delhi, India

Delhi is one of the most polluted cities worldwide and a comprehensive understanding and deeper insight into the air pollution and its sources is of high importance. We report 5 months of highly time-resolved measurements of non-refractory PM2.5 and black carbon (BC). Additionally, source apportionment based on positive matrix factorization (PMF) of the organic aerosol (OA) fraction is presented. The highest pollution levels are observed during winter in December/January. During that time, also uniquely high chloride concentrations are measured, which are sometimes even the most dominant NR-species in the morning hours. With increasing temperature, the total PM2.5 concentration decreases steadily, whereas the chloride concentrations decrease sharply. The concentrations measured in May are roughly 6 times lower than in December/January. PMF analysis resolves two primary factors, namely hydrocarbon-like (traffic-related) OA (HOA) and solid fuel combustion OA (SFC-OA), and one or two secondary factors depending on the season. The uncertainties of the PMF analysis are assessed by combining the random a-value approach and the bootstrap resampling technique of the PMF input. The uncertainties for the resolved factors range from ±18% to ±19% for HOA, ±7% to ±19% for SFC-OA and ±6 % to ±11% for the OOAs. The average correlation of HOA with eBCtr is R2 = 0.40, while SFC-OA has a correlation of R2 = 0.78 with eBCsf. Anthracene (m/z 178) and pyrene (m/z 202) (PAHs) are mostly explained by SFC-OA and follow its diurnal trend (R2 = 0.98 and R2 = 0.97). The secondary oxygenated aerosols are dominant during daytime. The average contribution during the afternoon hours (1 pm–5 pm) is 59% to the total OA mass, with contributions up to 96% in May. In contrast, the primary sources are more important during nighttime: the mean nightly contribution (22 pm–3 am) to the total OA mass is 48%, with contributions up to 88% during some episodes in April

Photochemical degradation affects the light absorption of water-soluble brown carbon in the South Asian outflow

Light-absorbing organic aerosols, known as brown carbon (BrC), counteract the overall cooling effect of aerosols on Earth's climate. The spatial and temporal dynamics of their light-absorbing properties are poorly constrained and unaccounted for in climate models, because of limited ambient observations. We combine carbon isotope forensics (delta C-13) with measurements of light absorption in a conceptual aging model to constrain the loss of light absorptivity (i.e., bleaching) of water-soluble BrC (WS-BrC) aerosols in one of the world's largest BrC emission regions-South Asia. On this regional scale, we find that atmospheric photochemical oxidation reduces the light absorption of WS-BrC by similar to 84% during transport over 6000 km in the Indo-Gangetic Plain, with an ambient first-order bleaching rate of 0.20 +/- 0.05 day(-1) during over-ocean transit across Bay of Bengal to an Indian Ocean receptor site. This study facilitates dynamic parameterization of WS-BrC absorption properties, thereby constraining BrC climate impact over South Asia