Reaserch On The Pollution Characteristics And Regional Diffusion Prediction Of Atmospheric Heavy Metals In The Central Urban Of Chengdu

With the rapid development of urban industry and motor vehicles massive increase, the invisible killer of heavy metals has unwittingly penetrated into every aspect of life, erosion of our body. Heavy metals contamination events common happened in recent years, from Hunan children lead poisoning cases, Shanxi Fengxiang children lead beyond standard to heavy metals polluted the "food basket" and so on, in 2009 heavy metals contamination cases caused the blood lead levels exceeded of 4035 people, 182 people cadmium exceeded, heavy metals had already been affecting our environment.The heavy metal element could persist in the environment with no degradation,the human inhaled heavy metals pollutants by breathing in the atmosphere, once accumulated in the body reaches a certain threshold, it will poison the human body,heavy metals long-term presence in the atmosphere may make up significant environmental and human potential harm.In the urban atmosphere heavy metal elements mainly had taken atmospheric particles and atmospheric water as important carrier,and entered into the urban environment ecosystem with different chemomorphosis,under the different meteorological conditions influence followed the carrier to make migration, concentration and transformation between various environment factors.In the Central Urban of Chengdu we had seted up sample monitoring points in various environmental functions,and taken the east and west monitoring points as long-term test point,gathered atmospheric particulate(TSP,PM10,PM2.5) and atmospheric water (water vapor,rain,fog) as the analysis samples of Cu,Pb,Fe,Mn,Zn,Cd,Hg,As,Cr9 heavy metals element as the object of study,combined with the previous research,carried on the investigation statistics to the region atmosphere heavy metal source of pollution and the energy consumption structure,according to emission coefficients used in the estimation of atmospheric heavy metal pollution of the source strength, systematic analysis of heavy metals in the atmosphere over time and space changes in differences presented pollution characteristics, and application of atmospheric diffusion model for regional atmospheric heavy metals in different sources and different weather conditions, Predicted its migration in the city, also used pollution index and fuzzy evaluation of atmospheric heavy metal pollution on the regional impact evaluation. The research indicated that the major polluting industries by the coal-based energy structure, the dust emissions from industrial sources and the transportation sources of dust emissions was the main source of heavy metals in the atmosphere,the following was the life emission sources and straw burning sources. On the monitoring samples for analysis, in the particulate the major heavy metal elements were Fe, Zn, Pb, Mn, Cu,from the time distribution,in the winter and spring,under the conditions of fog and haze various elements in high concentration, and concentration at night higher than during the day,from the overall area pollution degree,industrial area>traffic area> commercial area>agricultural area>cultural area>residential area, the heavy metal concentrations trend gradually aggravated from east to west and from south to north, the spread has the tendency which extends to the south.In the atmospheric water mainly heavy metal Cu, Zn, Fe, in the fog water the heavy metal concentration is higher than the water vapor and the rain water obviously,from the time distribution,was especially high in the winter and under the fog haze's special weather condition,from the area pollution degree,Traffic area>Industrial area>commercial area>agricultural area, the regional concentration is insignificant,but the atmospheric water heavy metal element's pollution level meteorological condition's influence,was obviously by the east to the west pollution the tendency which aggravated gradually.The atmospheric heavy metals under the influence of meteorological conditions and land surface conditions in the urban areas for horizontal and vertical diffusion, through the selection single industry point source, the path line source and the region life surface source we carry on the prediction the diffused ground concentration of the particulate, Fe, Zn, Cu,under the average wind speed PM10, Fe, Zn, Cu unstable state in the weak center 362m away from the point source reaches its peak,peak concentration from the surface order of stability>Strong unstable>neutral>weak unstable>unstable,under different stabilities condition,the concentration of static air time was higher than the ground concentration when the small wind speed,it showed that the static wind conditions had a great impact on regional diffusion. We could see the concentration achieves the peak value nearby dispersal center spool thread 400m in the city east and west axis when static air time, the diffusion density reduces rapidly,horizontal diffusion spread of pollution concentration profile as the normal distribution.Comparison of sunny, cloudy, haze, fog and rain in different humidity conditions, the humidity the greater the concentration of heavy metals in the smaller ground.By using the pollution index, the potential ecological risk index and fuzzy synthetic assessment, central city of heavy metals in atmospheric particulate matter pollution level is high, the degree of potential ecological risk of heavy metals TSP and PM2.5 more serious, and the total potential TSP ecological risk to moderate,heavy metal pollution of the atmosphere water integrated level was fog> rain>water vapor.