Research On Air Pollution Characteristics Of Typical Uninhabited Island

Uninhabited Island is not directly disturbed by human beings but may be influenced by long-term transportation and deposition of air pollutants.In this research,the characteristics of typical air pollutants including PM2.5,PM10,NOX,SO2,VOCs and GEM in the uninhabited island,i.e.Dajinshan Island,were analyzed,the deposition flux was calculated,and the potential sources and the environmental influence were discussed.The results showed that:(1)The average concentrations of PM2.5 and PM10 in Dajinshan Island were 37.92�38.66 ?g /m3 and 53.63 � 47.86 ?g / m3 respectively.The values were slightly higher than the air quality standards.The main components of PM2.5 were anion(41.9%),OC(29.8%),inorganic element(19.1%),EC(5.8%)and cation(3.4%).(2)The total VOCs in Dajinshan Island was 318.72 � 75.13 ?g / m3.The main components of VOCs were alkanes(58.85%),followed by aromatic hydrocarbons(23.5%),halogenated hydrocarbons(16.22%)and alkene alkyne(1.43%).Aromatic hydrocarbons were the key ozone generators and important precursors to secondary aerosols.(3)The atmospheric mercury concentration(6.02 � 3.67 ng / m3)in Dajinshan Island was much lower than the standard limit of atmospheric mercury(50 ng / m3)in China,but was 3-4 times higher than the background concentration in the northern hemisphere(1.5-2.0 ng / m3).(4)Backward trajectories indicated that most of the contaminated air was from the northwest of China while the marine air mass from the north improved the air quality of Daijinshan Island.(5)The amount of dustfall in Dajinshan Island was about 59.4 t/ yr and the amount of combustible material was about 45.36 t/ yr.The settling flux of Cu,Zn and Mn in the dustfall was much higher than the values of other elements.The results of enrichment factor analysis showed that,As,Pb,Zn,Se and Cu were mainly derived from human activities.(6)The main cations in precipitation in Daijinshan Island were Ca2+(36.10%)and Na+(13.38%);the main anions were SO42-(24.53%)and NO3-(20.75%).The correlation among Ca2+,K+,Mg2+ and Na+ was strong,which indicated that the metal ions in the air particles entered precipitation in the form of sulfate.(7)The results of soil evaluation showed serious Hg pollution in Daijinshan Island,which may cause extremely serious ecological damage.Cd pollution was moderate and may cause strong ecological damage.The surface soil was not contaminated by Pb,Cr,As,Cu or Zn.Correlation analysis showed significant correlation between Hg and other metals such as Cd,Pb,Cr,As and Cu,indicating external sources.The spatial autocorrelation analysis of heavy metals suggested non-point source pollution,which may result from atmospheric deposition.Based on this research,an atmospheric automatic monitoring platform was established in Daijinshan Island considering the nonnegligible environmental pollution.The platform can provide scientific support for the real-time monitoring of the air pollution in Daijinshan Island.