Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) distribution in wetlands: A case study using Alternanthera ficoidea (L.) plant in West Bengal, India.

This study presents the first attempt on plant biomonitoring of the polycyclic aromatic hydrocarbons (PAHs) pollution in East Kolkata Wetland (EKW), a Ramsar site in India, using Alternanthera ficoidea (L.). A polluted site, Captain Bheri (CB) and a control area, Kansabati River Basin (KRB) are chosen to compare the severity of the PAHs pollution of the wetland by examining wetland sediment and wetland plant parts (leaf, root, stem, rhizobium). Current study evaluates a fourfold higher concentration of 16 USEPA PAHs in CB sediment than in KRB, resulting significant carcinogenic risk in CB, as the Benzo[a]pyrene equivalent toxicity value exceeded the threshold limit suggested by the Canadian soil quality guidelines. In this context, A. ficoidea, a common wetland weed, appears to be a tolerant plant species with an air pollution tolerance index (APTI) value higher than 17. The accumulation pattern of ∑PAHs (μg g) at CB and KRB areas in leaves (420.23 ± 0.60 and 46.04 ± 8.59), stems (230.83 ± 4.87 and 29.14 ± 2.47), roots (68.45 ± 7.63 and 20.7 ± 3.72) and rhizobium (84.42 ± 7.42 and 25.37 ± 3.73) confirms its biomonitoring efficiency. The study found a strong positive correlation between lipid content and PAHs accumulation in plant parts (CB: r = 0.9944, KRB: r = 0.9916), signifying highest PAHs uptake by leaves. The high bioconcentration factor supports PAHs uptake via air-to-leaf route and likewise high translocation factor endorse root-to-leaf route for leaf bioaccumulation. Source apportionment analysis based on Diagnostic Ratios revealed mixed sources (pyrogenic and petrogenic) of PAHs in the polluted area. Therefore, A. ficoidea deserves attention as biomonitoring plant species in EKW PAHs pollution control.