China's failure to control nitrogen emissions could mar its success in reducing environmental levels of sulphur dioxide (SO2), a new study finds.
Both nitrogen and sulphur emissions are major contributors to soil acidity and environmental pollution.
Although China is on target to meet its goal of reducing sulphur dioxide emissions by 10 per cent between 2005 and 2010 — Chinese Premier Wen Jiabao announced in March this year that SO2 emissions have been reduced by 8.95 per cent in the last three years — researchers report that its nitrogen emissions are climbing dramatically.
Writing in Environmental Science and Technology this month (1 November) , the researchers predict that the country's emissions of nitrous oxides (NOx) and ammonia (NH3) will rise by 30 and 57 per cent respectively from 2005 to 2020.
Fossil fuel combustion in power plants and vehicles are China's main source of NOx discharges, while livestock farming and fertilisers are to blame for the bulk of its NH3 emissions.
In China' industrial sector, there is currently no nitrogen emission standard for coal combustion boilers, as a result of which emission control measures are rarely taken.
Additionally, nitrogen emissions from transportation are unlikely to diminish while vehicle numbers continue to escalate in China's cities.
Statistics released by the Ministry of Public Security last month (October) found that there are now more than 180 million vehicles in China compared to around 160 million at the end of 2007. The country sold 9.38 million vehicles in 2008, while Brazil and India sold 2.82 and 1.94 million, respectively.
"We want to suggest to the government that in parallel with controlling sulphur dioxide, we need to pay attention to nitrogen oxide," Lei Duan, study co-author and environmental scientist at Tsinghua University, told SciDev.Net.
The research group concluded: "Abatement of nitrogen emissions and deposition will be a major challenge to China, requiring policy development and technology investments. To mitigate acidification in the future, China needs a multi-pollutant control strategy that integrates measures to reduce sulphur, nitrogen and particulate matter."
Xu Xiaobin, chief researcher at the Chinese Academy of Meteorological Science, added: "This research could provide a basis for decision-making. That is, should we should focus on reducing SO2 or should we keep our eyes wide open and follow an integrated policy?"
Environmental Science and Technology 43 (21)(2009)