Long–range transport of soil dust and smoke pollution in the South Asian region

The study reports snow chemistry and long range transport of pollutants at Gulmarg in north-western Himalayan region of India during winters of 2012-2013. The pH of snowmelt varied between 5.16 and 7.68 with an average of 5.90. The frequency distribution of pH of snowmelt showed that the maximum number of samples (31%) had pH between 6.81 and 7.20. However, 12% samples were observed to be acidic (below 5.6 respectively. Both local emissions as well as long range transport (LRT) of pollutants were found to be the sources of these ionic species. Backward airmass trajectory calculations showed that this site received airmasses from six major sectors i.e., i) North Atlantic Ocean origin (NAO), ii) African origin (Af), iii) Middle East origin (ME), iv) European origin (Eu), v) Western India origin (InW), vi) Pakistan origin (Pk). The highest average pH (7.58) of the snowfall was noticed during InW airmasses which had the lowest ratios of nssSO 4 2-/nssCa 2+ and NO 3 -/nssCa 2+ . Very high pH has been observed in precipitation samples at Indian sites due to buffering of acidic components by atmospheric dust rich in CaCO 3 . The lowest pH (4.94) was noticed for ME airmasses which had the highest nssSO 4 2-/nssCa 2+ and NO 3 -/nssCa 2+ ratios. Data of present study was compared with a study reported almost three decades ago. We noticed a drastic increase in the concentrations of anthropogenic components such as nssSO 4 2-(114%), NO 3 -(109%) and NH 4 + (90%). This is probably due to increase in LRT of pollutants as well as local activities during past three decades.

Section: Clusterwise Chemical Composition Of Snowmeltsupporting

confidence: 59%

Long Range Transport and Wet Deposition Fluxes of Major Chemical Species in Snow at Gulmarg in North Western Himalayas (India)

Kumar

Singh

Gupta

et al. 2016

“…During the rest of the year, the strong correlation observed in winter disappears and at times the OC and S are decoupled. High S, OC, and BC concentrations may come from local traffic and/or long range transport (Begum et al, 2011c). Previous studies showed that back trajectory provided evidence of long-range transport of PM 2.5 and BC (Begum et al, 2009).…”

Section: Correlation Of Oc and Bc Ratio With Sulfate Concentrationmentioning

confidence: 99%

“…Since the BC concentration showed dependency on the wind direction (Begum et al, 2011c) and temperature, it might be concluded that the dominant sources of BC are local. The low OC/BC ratio is then attributed to local emissions: traffic, biomass burning or brick kilns.…”

Section: Estimated Secondary Organic Carbon Concentrationsmentioning

confidence: 99%

Organic and Black Carbon in PM2.5 at an Urban Site at Dhaka, Bangladesh

Begum

Hossain

Nahar

et al. 2012

Self Cite

The results from 1-year of measurements of PM 2.5 , organic carbon (OC) and black carbon (BC) concentrations are presented for an urban traffic-influenced site, the Farm Gate in Dhaka, Bangladesh. The measurements were based on sampling using two Air Metrics simultaneously operating samplers. The concentrations of OC and BC concentrations in PM 2.5 varied from 5-96 μg/m 3 and 4-48 μg/m 3 , respectively. The concentrations of PM 2.5 varied from 11-328 μg/m 3 . The annual particulate organic matter (POM) accounted for 46 ± 11% in PM 2.5 whereas BC stayed at 33 ± 12%. The effects of meteorological conditions on the variability of OC and BC concentration were examined and the contribution of secondary organic aerosol to the total OC was calculated. The concentrations of OC and BC relative to the total PM 2.5 are high and have good correlation with wind speed and temperature. The OC/BC ratio correlated with wind speed, temperature and sulfur concentration. Based on these relationships, it can be concluded that both local and regional sources of OC and BC are important. The local sources are traffic, coal and biomass burning. Distant sources include areas where there is extensive agricultural burning.

“…For example, the five key elements commonly associated with soil dust are Al, Si, Ca, Ti and Fe (Begum et al, 2011). K is often considered a marker for smoke, and S is an indicator of secondary sulfate, produced by the conversion of gaseous SO 2 to particulate sulfate in the presence of sunlight and water vapour (Seinfeld and Pandis, 1998).…”

Section: Sample Collection and Analysismentioning

confidence: 99%

Particulate Pollution in the Sydney Region: Source Diagnostics and Synoptic Controls

Crawford

Griffiths

Cohen

et al. 2016

Self Cite

Airborne particulate matter (PM 2.5 ) was sampled at Richmond and Liverpool, located in the Sydney Basin, Australia, and ion beam analysis was used to obtain the elemental composition. Using self-organising maps to classify synoptic weather systems, it was found that high PM 2.5 concentrations were associated with high pressure systems located to the east of the sampling sites. The highest median sulfur was associated with weak synoptic conditions and high soil dust days were more often associated with frontal systems.To investigate the effect of local flows in the Sydney Basin, the Weather Research and Forecasting model (WRF) was used to generate meteorological data of 12 km resolution. A comparison was made between back trajectories generated using the higher-resolution WRF data, the 0.5° by 0.5° Climate Forecast System data and the 1° by 1° Global Data Assimilation System data. It was found that for high soil dust days, there were small differences between the different back trajectories. However, under weak synoptic conditions (high sulfur days), the back trajectories generated from higher resolution data showed larger variations over a 24 hr period. This was attributed to the meandering of local winds and seabreezes.Lower altitude back trajectories, generated from low resolution data, passed more often over the power stations located on the western side of the Great Dividing Range (while the sampling sites are on the east). This demonstrates the need for higher resolution meteorological data for generating low altitude back trajectories when the source and receptor are separated by hilly terrain.In estimating the number of high sulfur days for which a power station was crossed, there was up to 20% difference at Liverpool and up to 10% difference at Richmond, between back trajectories starting at different altitudes and generated from meteorological data of three different resolutions.