Quantification and Source Identification of Polycyclic Aromatic Hydrocarbons in Core Sediments from Sundarban Mangrove Wetland, India

The distribution and potential sources of 16 polycyclic aromatic hydrocarbons (PAHs) in sediment cores (< 63 mu m particle size) of the Sundarban mangrove wetland, northeastern coast of Bay of Bengal (India), were investigated by gas chromatography coupled to mass spectrometry. The total concentrations of 16 PAHs (a(16)PAHs) ranged from 132 to 2938 ng/g, with a mean of 634 ng/g, and the sum of 10 out of 16 priority PAHs (a(10)PAH) varied from 123 to 2441 ng/g, with a mean of 555 ng/g, and the 5 carcinogenic PAHs (benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, and dibenz[a,h]anthracene) accounted for 68-73% of the priority PAHs. Maximum concentrations of the sediment core were obtained at subsoil depth of 12-16 cm. The prevalence of four to six aromatic ring PAHs and cross-plots of specific isomer ratios such as phenanthrene/anthracene, fluoranthene/pyrene, and methylphenanthrenes/phenanthrene suggested the predominance of wood and coal combustion sources, the atmospheric deposition, and surface runoff to be the major transport pathways. A good correlation existed between the benzo[a]pyrene level and the total PAH concentrations, making this compound a potential molecular marker for PAH pollution. Total TEQ (S) (carc) values calculated for samples varied from 6.95 ng/g TEQ (S) (carc) to 119 ng/g TEQ (S) (carc) , with an average of 59 ng/g dry weight TEQ (S) (carc) . The baseline data can be used for regular monitoring, considering the industrial and agricultural growth around this coastal environment.