Preliminary Study On The Emission Situation Of The Main Persistant Organic Pollutants In Guangdong Province, China

The harm of Persistent Organic Pollutants has been recognized by the whole world, and the widespread occurrence of these compounds and their adverse impacts on the ecosystem and human health have been widely concerned by scientists, policy constituter and international conferences. As starting point of any policy to decrease the environmental burden by dioxins (Particle-bound polychlorinated dibenzo-p-dioxins and dibenzofurans, PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs), a quantitative overview of their sources is essential. The similar research has been regarded in the world. Until now, very little was known about emissions of dioxins and PAHs in the regional and country scale in China, except those in Hong Kong and Taiwan. An effort was made to collect data set of emission factors ( EFs) from the literature, and use an emission inventory model to assess the emissions of dioxins(PCDD/Fs) and PAHs in Guangdong Province in this article. In addition, waste incineration and thermal power plants were studied especially, and the improved model was used to estimate the emmision from the waste incineration based on the actual situation in Guangdong. Geographical distribution and temporal change, as well as the emission sources, were discussed in the article.The results indicate that improved model should be used to assess PCDD/Fs emission in waste incineration plants, and it is improper to use the inventory model suggested by the Environmental Agency of the United Nations simply. The incineration quantity in waste incineration plants account for over 70% of total waste incineration, but the PCDD/Fs emission contribution was only 2.6%-22.7%. Since the reform and open policy was carried out in China, incineration quantity has been growing dramatically in waste incineration power plants; however, rigid regulations and advanced technologies have significantly decreased the amount of PCDD/Fs emission. The results indicate a gradually increase trend in emission of PCDD/Fs under the investigated period (1992-2003). The annual total emission was less than 60g TEQ (simple waste incineration was not included) . Estimations have showed that the main contribution to emissions is made by fossil fuel combustion, which occupied over 50%.The PCDD/Fs emission in Guangdong Province in 2002 is 61.92g TEQ after simple waste incineration emission was added to the inventory. The uncertainties of emission results were also analyzed based on the variations of the concerned emission factors. At the confidence interval of 75 %, there were around 2-5g TEQ of magnitude uncertainties for the emission sources investigated. Residential energy consumption was the main source of PCDD/Fs in European, account for a quarter of the total emission, while industry was the main source in Guangdong Province. PCDD/Fs emission from industrial energy combustion and industrial processes contributed 61% to the total emission in Guangdong Province in 2002.Therefore; efforts should be made to control the dioxins emission from industry. Dioxins emission from transportation has been wave growing in Guangdong Province during 1992-200.3, the emission level was higher than that in the European since 1994, and was gradually close to its maximum, the results indicate that more attention should be paid to transportation in order to control PCDD/Fs emission in Guangdong Province.PAHs emission in Guangdong Province is 54873.61kg in 2003, the power generation, industrial coal combustion, non-transportation oil combustion and natural gas combustion account 11%, 11% and 9% of the total emission respectively. The emission from Guangzhou and Shanwei are the maximum and the minimum in the 21 cities. Coal combustion was still the main energy in Guangdong, it contributes 80% to the total PAHs emission, and residential coal combustion was the main source, account for 69% of the total, this situation was similar to that in Europe.It was estimated that the total CO₂, PAHs and PCDD/Fs emission from the thermal power plants in Guangdong were 3114.17Mt, 8035.61kg and 11.46g TEQ respectively in 2003. The CO₂ emission in Pearl River delta account for more than 70% of the total emission, however, CO₂ emission per unit GDP in Pearl River delta is lower than the average level of Guangdong province.