Effect of Land Use Change on Selected Greenhouse Gas and Trace Gas Emissions:
A case study on the Map Ta Phut Industrial Estate, Thailand

Sangchan Limjirakan, D.Sc.
The Environmental Research Institute Chulalongkon University Bangkok Thailand

Land was the primary factor of production in agricultural-oriented Thai economy in the past. Increased in industrial development over the last decade, however, led to a large scale of land use change from agricultural base to industrial base, especially, land development under the Eastern Seaboard Program which strongly supported by the Thai government. These kinds of development have caused unexpected and unavoidable impacts on communities and environment nearby. Remote sensing technology in combination with geographic information system (GIS) were be used to render reliable information of land use change in Rayong during the 10-year period. The LANDSAT TM imageries acquired in 1987, 1990, 1994, and 1997 were classified into 6 significant land use/land cover types, namely, forest, agriculture, water bodies, industrial area, urban/building, and barren/others. The conversion of forest land to agricultural land and the conversion of agricultural land to water bodies and industrial areas are the main greatly changes observed. This picture reflects to the national policy and the growth of economy during that time. It should be noted that the former agricultural areas used to be planted major economic cash crops of the nation such as sugar cane, cassava, pineapple, and mix orchards. The Map Ta Phut Industrial Estate located in Rayong was selected to study the effect of land use change (from agricultural land to industrial area) on emissions of greenhouse gases and trace gases. The major industries are petrochemical industry, chemical and fertilizer industry, steel industry, oil refinery industry, and utility industry. The selected greenhouse gas including methane (CH4), nitrous oxide (N2O), non-methane volatile organic compounds (NMVOC) were studied from 3 industrial processes of petrochemical industry, chemical and fertilizer industry, and steel industry. While selected trace gas emissions were focused on sulfur dioxide (SO2), and nitrogen dioxide (NO2) from industrial processes of all industries in the Estate.

The Industrial Source Complex (ISC) Dispersion Models, the EPA-recommended Regulatory Model, were be used with meteorological data for studying 1-hr maximum concentrations of the above mentioned gases. The land use map within a radius of 10-kilometers from the Industrial Estate in 1997 was used as a base map. Simulation results of base case presented the maximum ground level concentrations of SO2 was well below the ambient air quality standards of Thailand, while the maximum GLC of NO2 in 1-hr almost equaled to the standard. However, these values were higher than ambient air quality monitoring data in 1999. For 6 different scenarios simulations, 1-hr maximum GLCs of SO2 and NO2 of all scenarios were exceeded the ambient air quality standards and ambient air quality monitoring data as well. The possible effects of CH4, N2O, NMVOC, SO2, and NO2 emissions on people in the community nearby, were calculated and represented by the isopleths of 1-hr maximum concentrations at the nearest populous community for all cases studied. The concentrations of SO2 were well below the ambient air quality standard, while NO2 concentrations were exceeded the standard when annual industrial production increased double times. However, the concentrations of SO2, and NO2 were higher than the ambient air quality monitoring data.

It could be concluded that under different scenarios, emissions of SO2 and NO2 emitting from industrial processes in the Estate expected to cause some significant effects on existing ambient air quality of the study area at some certain degrees. For CH4, N2O, and NMVOC emitted from non-combustion industrial processes, there is currently no ambient air quality standard to compare. Nonetheless, concentrations of these gas emissions seem to be high. They would cause some effects on the community nearby in terms of human health and some nuisances. The magnitude of which is highly uncertain. This likewise could have any affect on at least a local scale to a regional scale of climate change as well. The study also makes some recommendations on further research that defined context responding adequate to policy making process and the strategy framework for national greenhouse response. The sustainable development model is also recommended for the national policy implications as well.