Abstract
The air-water exchange of polycyclic aromatic hydrocarbons (PAHs) is an important process in determining the fate, transport and chemical loadings of these contaminants in the atmosphere and water bodies. Concentration levels of PAHs in air (gaseous and particulate) and surface water were investigated in the environments of two polluted lagoons along the eastern coast of the Red Sea to study air water exchange and dry deposition fluxes. Nine priority parent PAHs and nine methylated PAHs were identified and quantified by GC-MS. The range of total PAHs in surface water was from 120.29 ng L−1 to 524.45 ng L−1 (average: 308.7 ng L−1, n = 19). The PAHs levels in air recorded significant rise form the previous study. The probable sources of dissolved PAHs in water were found predominantly to be of petrogenic origin in one lagoon and of pyrogenic origin in the other lagoon. The dry deposition fluxes for individual congeners ranged between 0.01 ng m−2d−1 to 2.82 μg m−2d−1. After Henry's law constant corrections for temperature and salinity; the air-water exchange fluxes were found in the range of −9.7 × 104 to 8.6 × 106 ngm−2d−1 with an average of 6.8 × 105 ngm−2d−1. Beside the other sources of PAHs in the studied lagoons, high temperature and wastewater dumping might affect the magnitude and direction of air-water exchange fluxes.
•With constancy of PAHs levels in water, its levels in air were found ten-fold higher than the previous studies.•Absence of precipitation events reinforced the redundancy of PAHs levels in air.•High volatilization fluxes of PAHs were observed in the study area.•Domestic waste waters and high temperature strongly affect the PAHs levels in the lagoons' environmental matrices.