Determining Air−Water Exchange, Spatial and Temporal Trends of Freely Dissolved PAHs in an Urban Estuary Using Passive Polyethylene Samplers

Abstract

Passive polyethylene (PE) samplers were deployed at six locations within Narragansett Bay (RI, USA) to determine sources and trends of freely dissolved and gas-phase polycyclic aromatic hydrocarbons (PAHs) from May to November 2006. Freely dissolved aqueous concentrations of PAHs were dominated by fluoranthene, pyrene, and phenanthrene, at concentrations ranging from tens to thousands of pg/L. These were also the dominant PAHs in the gas phase, at hundreds to thousands of pg/m3. All stations mostly followed the same temporal trends, with highest concentrations (up to 7300 pg/L for sum PAHs) during the second of 11 deployments, coinciding with a major rainstorm. Strong correlations of sum PAHs with river flows and wastewater treatment plant discharges highlighted the importance of rainfall in mobilizing PAHs from a combination of runoff and atmospheric washout. PAH concentrations declined through consecutive deployments III to V, which could be explained by an exponential decay due to flushing with cleaner ocean water during tides. The estimated residence time (tres) of the PAH pulse was 24 days, close to an earlier estimate of tres of 26 days for freshwater in the Bay. Air-water exchange gradients indicated net volatilization of most PAHs closest to Providence. Further south in the Bay, gradients had changed to mostly net uptake of the more volatile PAHs, but net volatilization for the less volatile PAHs. Based on characteristic PAH ratios, freely dissolved PAHs at most sites originated from the combustion of fossil fuels; only two sites were at times affected by fuel spill-derived PAHs.

Tracking human footprints in Antarctica through passive sampling of polycyclic aromatic hydrocarbons in inland lakes

“…The R s of target PAHs ranged from 0.38 L d À1 (2,3,5-TNap in Heart Lake) to 120 L d À1 (BaA in Lake Reid) (Table S5), and slightly increased with increasing log K pew . This increasing trend was also observed for PAHs with PE samplers in Narragansett Bay, Rhode Island, USA (Lohmann et al, 2011). The errors of R s for individual analytes depend on the errors in the fitting parameters a and b, i.e., log R s-PRC ¼ a  log K pew þ b.…”

Temporal variation and spatial distribution of PAH in water of Three Gorges Reservoir during the complete impoundment period

“…Less rainfall is associated with lower pollutant impact by wet deposition. As a matter of fact, dry deposits are highly polluted in urban atmosphere (Lohmann et al 2011). Bomboi and Hernandez (1991) (Yin et al 2011).…”

Diffusive flux of PAHs across sediment–water and water–air interfaces at urban superfund sites

“…Passive sampling allows for a direct measurement of freely dissolved and vapor phase concentrations, avoiding filter bias and providing a time-weighted average incorporating episodic events [23]. Several studies have demonstrated the use of passive samplers to measure the diffusive flux of PAHs across air-water interfaces [15,19,[24][25][26][27]. Fewer studies have utilized passive samplers to measure the diffusive flux of PAHs between porewater and water [28][29][30].…”