上海地区酸雨类型格局转变研究

REGIME SHIFT OF ACID RAIN TYPE IN AREA OF SHANGHAI

采用STARS(Sequentialt-test analysis of regime shifts),以降水中SO24-、NO3-以及SO42-/NO3-为指标,研究了上海地区酸雨类型在1991～2006年的格局转变规律。上海地区降水中SO42-含量在1991～2006年具有两种格局,2004年发生转变;转变前的SO42-含量平均12.670mg/L,转变后SO42-含量大幅度降低,平均6.525mg/L;降水中NO3-含量存在3种格局,两次转变;1996年转变前的NO3-浓度相对较低,平均1.842mg/L;此次转变后升高,平均2.622mg/L;2005年再次发生转变,使得NO3-含量下降,平均1.998mg/L;与NO3-含量的格局类似,SO24-/NO3-也存在着3种格局,两次转变;1995年转变前,SO42-/NO3-平均7.316;此次格局转变后,SO42-/NO3-降为5.666;2000年的格局转变中SO24-/NO3-降为3.635。表明NO3-对酸雨的贡献逐渐增加,SO42-对酸雨的贡献逐渐减弱,酸雨类型逐渐由硫酸型酸雨过渡成硫酸和硝酸混合型酸雨,并逐渐接近硝酸型酸雨。上海地区酸雨类型格局在1991～2006年发生5次格局转变,其格局转变指数(RSI)在1995、1996,2000,2004和2005年分别为0.826、0.260、0.959,1.378和0.066。

At present,acid rain has aroused great concerns of people,but little previous research has been completed on regime shift of acid rain type. Based on the content of SO4^2-, NO3^- and SO4^2-/NO3^- in the rain of Shanghai,the regime shifts of acid rain type from 1991 to 2006 ,were studied by adopting the STARS（sequential t-test analysis of regime shifts）. There were two regimes of the SO4^2- content;one shift happened in 2004. Before the shift,it was 12. 670 mg/L on average;after that,it decreased sharply to 6. 525 mg/L. Whereas, there were three regimes, two shifts, of the NO3 content. Before the first regime shift in 1996,it was 1. 842 mg/L on average,after that,it increased to 2. 622 mg/L on average till the second shift in 2005, then it decreased again to below 2. 000 mg/L on average. Similar to the regime of NO3^- content,there were also three regimes of SO4^2-/NO3^- , shift twice. Before the first shift in 1995, SO4^2- /NO3^- was 7. 316; after that,it decreased to 5. 666 till the second shift in 2000,then it decreased further to 3. 635 on average. These indicated that during 1991-2006 in area of Shanghai,the contribution of NO3^- to acid rain increased,while the contribution of SO4^2- to acid rain decreased. The acid rain types were turning from sulfuric acid rain to sulfuric and nitric acid rain complex type,approaching the nitric acid rain type. Altogether,there were 5 regime shifts of acid rain type during 1991-2006 in area of Shanghai. The regime shift indices （RSI） were 0. 826,0. 260,0. 959,1. 378 and 0. 066 in 1995,1996,2000,2004 and 2005,accordingly.