Statistic Analysis of Arid Rain Character in Loess Plateau City of Longdong

Based on acid rain monitoring data of 11 years in Xifeng climatological station, and main pollutant source data samples in north of Qingyang city, according to acid rain monitoring standard made by China Meteorological Administration, acid rain characteristics were analyzed statistically. Results show that acid rain degree weakened with fluctuation during 1992~2000 in Qingyang city and boosted up during 2001~2002 without considering influence of wind advection, the frequency occurring acid rain in a year declined yearly, the monthly acid rain degree is maximum in March and November, PH≤0.48, the frequency occurring acid rain is maximum of 24%~35% from August to November. Considering the influence of wind advection in or before rain, the influence of pollutant source in the north on yearly acid rain intensity isn't obvious, but it can make the frequency occurring acid rain increase in a year, the influence on acid rain degree is marked in October, PH reduced 0.3, the influence on monthly acid rain occurring is mainly in summer. The study revealed the fact that acid rain exists over Longdong loess plateau, it has an active meaning to cure acid rain harm and to protect ecology environment.