Study On The Effects Of Compound Pollution Of Simulated Acid Rain And Heavy Metal Of Pb、Cd On Pakchoi

Since1872, Robert Angus Smith,a British chemist proposed the concept of acidrain, and then this problem caused wide attention of scholars both at home and abroadwho have been doing a large number of related research. At present, acid rain hasbecome one of the top ten world environmental problems, and our country hasbecome the third largest acid rain regions after Europe and North America in theworld. Along with our country’s economic development, the rapid development ofurbanization and industrialization, there will be eventually more and more serious airpollution and acid rain problems. And increasingly serious acid rain problem bringhuge impact on terrestrial ecosystems and result in huge economic losses, which hasbecome one of the important factors of restricting our forestry production andeconomic and social development.Due to the global industrialization, a large number of materials with potentialpoisonous and side effects turn into the biosphere, including heavy metals. In the past50years, through the rough calculation, the cadmium emissions to globalenvironment reached22000tons,783000tons of lead. After soil contaminated, theheavy metal on the one hand enter human body by means of the enrichment of cropgrowing on it and through the food chain, on the other hand the heavy metal on thetop soil can through the dust channel into the human body, which eventually endangerhuman health of body and mind. In the history environmental hazards events inducedby heavy metals took place many times. China has listed heavy metal pollutionprevention and control on the12th five-year plan, and our land involving11provincesand25areas has been polluted by heavy metals such as cadmium, lead, contaminatedcultivated land areas exceed more than20%of the total areas. In recent years, acidrain frequently happened and lead to soil acidification which can directly harm theplant and also enhances ion mobility of heavy metals in the soil, which increase plantenrichment, and cause indirect damage to plants. Acid rain can also cause activitychanges of heavy metals in plants, reducing the resistance and the quality of plants. Therefore, the research on the impact of heavy metals compound pollution with thecondition of acid rain on crop has practical significance.This study uses large leafy vegetables pakchoi as the research object which issensitive to acid rain stress effect and grows widely in the northeast, and discusses theeffects on the physiological and nutritional quality of pakchoi under the condition ofdifferent intensity of acid rain and different heavy metals concentration, andvegetables enrichment of the heavy metal content on different intensity of acid rain,according to the obtained data, after discussing the response of pakchoi to thedifferent intensity of acid rain and different heavy metal concentration, there couldprovide basic experimental data and theoretical basis on revealing the impacts of thecompound pollution of acid rain and heavy metals in China on agricultural ecosystem.The research results of physiological indexes of pakchoi under the condition ofsimulated different acid rain intensity and different concentrations of heavy metalsshow that the increasing intensity of acid rain led to gradual decrease of pakchoichlorophyll content, namely the inhibition of chlorophyll synthesis of pakchoi anddecline in photosynthetic capacity. Different heavy metals combination has significantinfluence on the chlorophyll content in plants, which lead to plants of group two moresensitive to the change of the pH value of acid rain, namely the combination of highlead and low cadmium.The research results of nutritional indexes of pakchoi under the condition ofsimulated different acid rain intensity and different concentrations of heavy metalsshow that the simulated acid rain can obviously inhibit the synthesis of soluble sugarand vitamin C in the plants, and the more increase of the intensity of acid rain, themore significant inhibitory effect. Different pH value of acid rain has significantimpact on the soluble sugar content difference of plants, and the impact on vitamin Cis not obvious.The research results of enrichment of heavy metal content in plant undersimulation different intensity of acid rain show that with the decrease of the pH valueof acid rain, plants enrichment of heavy metal content get higher about both two heavy metals. Using binomial function can suitably simulate the two kinds of heavymetal concentration curve. For cadmium enrichment, the absorption rate graduallyincreases, while the lead reaches the highest absorption rate in the third week, whichreaches four to five times the speed of the increase of lead in plant.