Temporal variations and sources of Eastern Mediterranean aerosols based on a 9-year observation

摘要

Concentrations of 48 elements, NO_3~-, SO_4~(2-) , Cl~- , NH_4~+, and black carbon (BC) were determined in PM_(10) aerosols collected daily at a rural Eastern Mediterranean (EM) site (Antalya, 30.34°E, 36.47°N) from 1993 to 2001. Temporal variations (daily, seasonal and long term), sources and source regions of EM aerosols were delineated. Concentrations of elements with marine and crustal origin were more episodic as compared to anthropogenic ones. Most of the variables showed well defined seasonal cycles. Concentrations of crustal elements increased in summer while winter concentrations of marine elements were considerably higher than in summer. Trends in concentrations were analyzed using the Kendall test. Essentially, all elements showed decreasing trends. Sen's slope was applied to find the magnitude of the trends. The annual rate of decrease was found to change from 0.001 to 209 ng m~(-3). A receptor-based model, Positive Matrix Factorization (PMF), resolved five factors influencing the chemical composition of EM aerosols as airborne dust, oil combustion, coal combustion, motor vehicle emissions and sea salt. Potential Source Contribution Function (PSCF) analysis was performed to identify the likely areas influencing the chemical composition of aerosol samples. Local and remote sources were detected for the factors resolved by PMF. PSCF maps including backward trajectories at starting height of 900 hPa have indicated that North Africa is the major source contributing to the concentrations of variables associated with dust factor.