华东典型地区大气硫沉降通量的观测和模拟研究

本文使用中国科学院常熟和鹰潭生态实验站和气象站的观测资料，应用区域酸沉降模式系统（RegADMS）和大叶阻力相似模型来研究华东地区不同下垫面条件上的大气硫沉降问题，定量估计了农田下垫面上大气硫化物的沉降通量。SO2和硫酸盐的干沉降速率使用大叶阻力相似模型来估计，使用与降水量有关的参数化方案来确定湿沉降系数。结果表明，常熟地区农田下垫面的大气硫沉降通量为19．0gm^-2 a^-1，其中干沉降占42％；而位于江西红壤地区的鹰潭站的大气硫沉降通量为10．4gm^-2a^-1，其中干沉降占83％。比较发现，两地硫干沉降通量绝对值相差不大，但其在总沉降通量中所占的份额有较大差异；常熟站的硫湿沉降通量比鹰潭站要大9．23gm^-2a^-1，该差异是由两地污染状况和气象条件的不同造成。华东地区的年硫沉降总量为1．88Mt（1Mt=10^6t），其中72．8％沉降在农田下垫面上。硫沉降中43％是干沉降，57％是湿沉降。

OBSERVATIONAL AND NUMERICAL STUDIES ON ATMOSPHERIC SULFUR DEPOSITION OVER TYPICAL REGIONS OF EAST CHINA

Atmospheric sulfur deposition over typical regions of East China was investigated using both field measurement and numerical modeling.The measurement was conducted at the Ecological Experiment Stations of Changshu and Yingtan.The total sulfur deposition measured at the site is about 19.0 gm~(-2)a~(-1),of which 42% was dry deposition.The observed results in Changshu were compared with those from the Yingtan site,where total sulfur deposition was about 10.4 gm~(-2)a~(-1),of which 83% is dry deposition.The significant difference suggested the contrasting air pollution situations between the two sites.The regional acid deposition model system(RegADMS) was applied to simulate air sulfur deposition onto different landuse types over the study region,in which the dry deposition velocities of SO_(2)and sulfate aerosol(SO_4~(2-)) were estimated by use of a big leaf resistance analogy model and the wet scavenging coefficients were parameterized in terms of precipitation rate.The annual total sulfur deposition over East China was 1.88Mt(1 Mt=10~(6)ton),of which 72.8% was deposited onto farmland,dry deposition accounted for 43% in total sulfur deposited,and wet deposition was 57%.