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 μm 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 (∑16PAHs) ranged from 132 to 2938 ng/g, with a mean of 634 ng/g, and the sum of 10 out of 16 priority PAHs (∑10PAH) 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 TEQScarc values calculated for samples varied from 6.95 ng/g TEQScarc to 119 ng/g TEQScarc, with an average of 59 ng/g dry weight TEQScarc. The baseline data can be used for regular monitoring, considering the industrial and agricultural growth around this coastal environment.