重庆市铁山坪2001~2010年酸沉降变化

我国"十一五"期间实现了全国二氧化硫(SO2)排放总量削减10%以上的目标,但氮氧化物(NO x)排放量仍持续增长.为了评估排放的变化对酸沉降控制的效果,2001~2010年在重庆铁山坪连续开展了10 a的穿透水观测,结果表明该地区硫沉降有明显的下降趋势,而氮沉降有明显的上升趋势,总体上酸沉降有所下降.以上趋势和重庆市同期SO2排放量有所下降而NO x排放量持续增长的趋势是一致的,这表明我国酸沉降控制取得一定的效果.但是,2010年重庆铁山坪的穿透水硫沉降量和氮沉降量分别达到9.9 keq·(hm2·a)-1和4.5 keq·(hm2·a)-1.如果以此作为总沉降量的近似,将可能存在硫沉降被高估28%,氮沉降被低估50%的不确定性.以上硫沉降和氮沉降水平均达到甚至超过欧美在历史上酸沉降最严重时期的水平,表明重庆地区的酸沉降问题依然严重.

Trend in Acid Deposition at Tieshanping, Chonging During 2001-2010

Although the total emission of sulphure dioxide (SO₂) 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 SO₂ 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)^-1 and 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.