[Trend in acid deposition at Tieshanping, Chonging during 2001-2010].

Although the total emission of sulphure dioxide( SO 2) was reduced by more than 10% in the Eleventh Five-Year-Plan( 2006-2010) in China,the total emission of nitrogen oxides( NO x) in the same period kept increasing. In order to evaluate the effects of the emission changes on acid depostion,a ten-year monitoring on forest throughfall was carried out from 2001 to 2010 at Tieshanping,Chongqing in Southwestern China. The results indicated there was a significantly decreasing trend of sulphur deposition and an increasing trend of nitrogen deposition,which coincided well with the dicreasing trend of SO 2 emission and increasing tread of NO x emission in Chongqing,respectively. As the net effect,acid deposition was reduced by the emission contol. However,the total deposition of sulphur and nitrogen in 2010 was estimated to be 9. 9 keq·( hm2·a)- 1and 4. 5 keq·( hm2·a)- 1,respectively according to the throughfall data,with the former probably overestimated by 28% and the latter underestimated by 50%. Since both the sulphur deposition and nitrogen deposition are higher than the highest levels in the history in Europe and North America,acid deposition is still a serious issue in Chongqing.