Emission from field burning of crop residue, a common practice in many parts of the world today, has potential effects on air quality, atmosphere and climate. This study provides a comprehensive size and compositional characterization of particulate matter (PM) emission from rice straw (RS) burning using both in situ experiments (11 spread field burning) and laboratory hood experiments (3 pile and 6 spread burning) that were conducted during 2003–2006 in Thailand. The carbon balance and emission ratio method was used to determine PM emission factors (EF) in the field experiments. The obtained EFs varied from field to hood experiments reflecting multiple factors affecting combustion and emission. In the hood experiments, EFs were found to be depending on the burning types (spread or pile), moisture content and the combustion efficiency. In addition, in the field experiments, burning rate and EF were also influenced by weather conditions, i.e. wind. Hood pile burning produced significantly higher EF (20±8 g kg−1 RS) than hood spread burning (4.7±2.2 g kg−1 RS). The majority of PM emitted from the field burning was PM2.5 with EF of 5.1±0.7 g m−2 or 8.3±2.7 g kg−1 RS burned. The coarse PM fraction (PM10-2.5) was mainly generated by fire attention activities and was relatively small, hence the resulting EF of PM10 (9.4±3.5 g kg−1 RS) was not significantly higher than PM2.5. PM size distribution was measured across 8 size ranges (from <0.4 μm to >9.0 μm). The largest fractions of PM, EC and OC were associated with PM1.1. The most significant components in PM2.5 and PM10 include OC, water soluble ions and levoglucosan. Relative abundance of some methoxyphenols (e.g., acetylsyringone), PAHs (e.g., fluoranthene and pyrene), organochlorine pesticides and PCBs may also serve as additional signatures for the PM emission. Presence of these toxic compounds in PM of burning smoke increases the potential toxic effects of the emission. For illustration, an estimation of the annual RS field burning in Thailand was made using the obtained in situ field burning EFs and preliminary burning activity data.

Vehicular emissions have been playing a pivotal role in deteriorating air quality in many urban parts of Nepal causing adverse impacts upon the health of commuters and pedestrians attributed to severe respiratory diseases. Primary data such as the number of vehicles (N) were obtained using two-hour peak (8 am to 10 am) and two-hour nonpeak (1 pm to 3 pm) count, after which average annual vehicle kilometer (VKT) and fuel economy (F) required for emission load estimation were obtained from vehicle survey using the simple random sampling method, sampling size taken statistically under 5% margin of error. Secondary data in this study include emission factors and derived equations from a published article. The vehicular emission load of Bhaktapur Municipality were found to be 3,310 tons/year including CO2, CO, NOx, HC, and PM10 of which CO2 accounts for 94.36% of total emissions followed by CO (4.39%), HC (0.72%), NOx (0.35%), and PM10 (0.18%), respectively. Significant positive correlation was found (r = 0.92, p = 0.002 ) between CO2 and PM10 (r = 0.87, p = 0.009 ), between CO2 and NOx (r = 0.90, p = 0.004 ), between CO and HC (r = 0.74, p = 0.05 ), and between NOx and PM10, respectively. The scenario analysis shows that the introduction of electric vehicles at different rates within the municipality can reduce the emissions to a significant amount. Exponential growth in vehicular gaseous pollutants potent to jeopardize the environment and welfare can become inevitable in the future if clean energy technology is not promoted early.

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Not available.DOI: http://dx.doi.org/10.3126/hn.v16i0.12210Hydro NepalJournal of water, energy and environmentIssue. 16, 2015,Page : 1-1Upload date: March 1, 2015