Distributions,Seasonal Variation And Assessment Of Ecolological Risk Of Dustfalls In Lanzhou City

Persistent Organic Pollutants are a series of high toxic, persistent, and bioaccumulated organic pollutants, which have a serious impact on both human health and the circumstance. It is more and more notable that they put the earth and all human being in danger because of their effect: making biology come across cancer, being abnormality, and being aberrance.Of the wide range of organic contaminants in the environment, polycyclic aromatic hydrocarbons (PAHs) are of concern because of several of them show a high carcinogenic and mutagenic activity, and Benzo[a]pyrene (BaP) was one of the most well known PAHs due to its carcinogenic properties. (PAHs is persistent, universal, and of huge harm like other POPs, and also, it keeps inpouring into the environment faster and faster, as the expansion of population and the development of industry. Thus, PAHs is a new host focus, and become more and more accounted of by scientists from all countries.Lanzhou is an industrial city and industrial pollution is serious. Meteorological conditions and special geographic environment of Lanzhou make air pollution worse.At present, the study of dustfall in Lanzhou is few, and it didn't show the distribution and sources of PAHs comprehensively.Organic analyses were carried out for dustfall samples after heating period at Lanzhou by GC/MS measurements. The results showed that 11 kinds of priority Polycyclic Aromatic Hydrocarbons in dustfall in Lanzhou were detected. The concentrations of NAP,FLUA,PHE,PYR and CHR were higher than others. The percentage of NAP,FLUA,PHE,PYR and CHR to∑PAH₁₁ was more than 70% in respective samples. The result showed that coal combustion was not the only predominant source, the source of vehicle emissions was important more and more these years. The concentrations and distribution of PAHs in dustfall were influenced strongly by sampling locations and environment around them. Compared with the corresponding quality guidelines, Chengguan area would have stronger ecological risk. In a 14-month observation period, the dust flux in LD site is lower than that in ER site clesrly. Seasonal trends of dust flux in ER site is winter >spring>summer(?) fall.There is a negative correlation between dust flux, wind speed and monthly average temperature in ER site. At LD site, the influence of wind speed and monthly average temperature to dust flux is little, and the Seasonal trends of precipitation is similar to that of dust flux. The concentrations of TOC at LD site(4.5%-24.71%, average12.82%) is higher than that at ER site(4.15%-22.48%, average9.45%).16 kinds of priority PAHs had been identified in all samples and methyl-PAHs are ubiquitous.