| Base on investigating the acidity , chemic compositions and monthly change character of precipitation on north Bank of the Yangtze River in Nanjing, a study on soil acidification and leaching of base cations with different pH of simulated acid rain, response of yield and quality forming in crops such as double-low oilseed rape and weak-gluten wheat to acid rain stress, adjusting to acid rain stress with different fertilizer application was carried out by spraying and soil columns leaching experiments, which provide scientific references for improving the oasis environment, modifying the cultivation technology of high yield and excellent quantity in crops, and increasing the benefit of quality and yield of agricultural products. Result showed as follows:1. The distribution characteristics of Nanjing acid rain are: influence of the acid rain is that outskirts greater than urban area. The acid rain occurrences ahead of time. Cations concentration and conduction in the acid rain is high.2. The frequency of acid rain in north Bank of the Yangtze River is 49.2 percent and there are obvious seasonal variety on it. The acid rain occurrence frequency is the highest in autumn and lowest in spring. The pH value of precipitation ranged from 4.17 to 8.34. Main anions of precipitation are SO42- and NO3- and cations are NH4+,Ca2+. The concentrations of heavy metals such as Pb,Cd,Cr,Cu,Hg are overstep the Chinese environmental quality standard. The main meteorological factors which influences to acidity of precipitation include wind velocity, direction of wind and rainfall. The acid rain frequency increase with wind velocity; Wind of ENE and ESE can appear the acid rain easily.3. Soil buffering played a dominant role in soil acidification in crop-lands. When pH≤3.5, which caused soil acidification, the soil was confined chiefly by acidity of acid rain. The pH>3.5, Soil buffering could play a important role and pH value of soil was higher and more stabler. The dissolution curve of soil base cations presented a linear varying on pH≤3.5 and log varying on pH>3.5. We built a new model from this.4. The dissolution of base cations could be decreased with rising from pH of acid rain, leaching amount and times, and enhanced with crop group growing. Ca had a greater amount and variation. In contrast, the release from K, Na, Mg could be feebleness under influence by acid rain. The plant height, leaf areas and fresh weights were diminished by acid rain stress. Surface of leaf appeared the more conspicuous sign of attsck. The flower damage rate had a greater growing in flower stage. In this time, the top of inflorescences occurred atrophied, some petals crinkled, pods and ears decreased, large amount of flower/fruitlet drop occurred. Under the acid rain stress, the cell plasma membrane permeability, malonic aldehyde (MDA) contents and peroxidase (POD) activity would increase correspondingly. The superoxide dismutase (SOD) and catalase (CAT) activity occurred fluctuation. Crops had a significant difference on physiological and biochemical characteristics under the acid rain stress.5. Simulated acid rain stress had a great harm to chloroplasts that it caused that total chlorophyll, rate of photosynthesis, accumulation of dry matter and seed fields failed. The content of rape crude fat follows a trend of decrease. The synthesis of soluble sugar and reduced sugar were suppressed. Contents of total free amino acid and soluble protein also decreased as the acidity became stronger.6. Acid rain accelerated glucosindate and erucic acid content of the double- low oilseed rape so that reduce the brand of double-low oilseed rape. Acid rain could cut down the protein and amino acid content of weak-gluten wheat, which former favorable to quality and latter don't. The mechanics and specific values of above indexes remain to be further explored.
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