Is a linear low-density polyethylene passive sampler suitable for long-term monitoring of polycyclic aromatic hydrocarbons in seawater? A case study of Masan Bay with bioavailability assessment

초록

Masan Bay, a semi-enclosed industrial embayment in South Korea, has been continuously impacted by urban and industrial inputs of polycyclic aromatic hydrocarbons (PAHs). Despite being subject to governmental environmental management, information on the bioavailable fraction of PAHs remains limited. Although passive samplers (PS) are widely used to determine freely dissolved concentrations, the long-term applicability of linear lowdensity polyethylene (LLDPE) in marine environments has not been systematically evaluated. To address this gap, LLDPE and low-density polyethylene (LDPE) were simultaneously deployed for 7 months at two sites, Samgwi (SG) and Yangdeok (YD), to determine time-weighted average concentrations (CTWA) and seasonal variability. CTWA values ranged from 1.2 to 6.5 ng/L at SG and from 2.0 to 6.7 ng/L at YD. Seasonal contributions of individual PAHs showed no substantial differences between the two samplers. Compared with previous studies, sediment PAH concentrations exhibited a declining trend. Porewater concentrations ranged from 1.5 to 16 ng/L and did not exceed toxicity-based benchmarks. Diffusive fluxes were predominantly directed from sediments to the overlying seawater. These findings demonstrate that LLDPE can be effectively applied alongside LDPE for long-term monitoring of PAHs and indicate relatively low ecological risk under current conditions in Masan Bay.

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