The aim of this project is to assist in stipulating a regulation to control the emission of heavy metals in the future. An emission database was constructed, containing the data of (1) distribution analysis, (2) contaminant source investigation and (3) emission amount measurement of seven heavy metals. On the other hand, both receptor (CMB) and diffusion (AERMOD) model were applied for contributor analysis in the surrounding area of Tainan City. Strategy of heavy metal control would be developed according to the combining results of emission database and modeling.
With respect to the survey of heavy metal emission by stationary pollution sources, field survey from 70 candidates indicated that the emission amount of lead, cadmium, and arsenic was 0.248, 0.021, and 0.068 ton respectively until June, 2011. Furthermore, results also showed that the main contributor for lead was electric-arc furnace (EAF) steelmaking process; for cadmium was both EAF steelmaking process and power generation process by boiler; for arsenic was secondary aluminum smelting process.
In addition, seasonal samplings, including particles and cascade, in 7 stations during February, April, August, and September, 2011 and another 2 samplings in the funnel was conducted. From the analysis results, concentration of lead, cadmium, arsenic, and nickel was all below the recommended annual standard from EU (6×10-3μg/m3).
For the results of modeling, the receptor site with maximum concentration of lead was Yong Kang Dist.; with maximum concentration of cadmium were both Yong Kang and Shan Shang Dist.; with maximum concentration of arsenic was Tainan Science Park of Southern Taiwan Science Park. However, for the integrity of confirming the heavy metal emission by combining the results from modeling and sampling, arsenic showed the highest integrity followed by cadmium and lead. The estimation of lead emission was obviously underestimated.