Fugacity gradients of hydrophobic organics across the air-water interface measured with a novel passive sampler

Fluorescent Visualization of Chemical Profiles across the Air–Water Interface

“…This result is in accordance with a previous finding that hydrophobic organic contaminants were accumulated at the air–water interface . Meanwhile, I ( z ) at C bulk = 100 μg L –1 (Figures B and S5) spiked with CTAB and FA to imitate field scenarios reveals much more subtle details near the air–water interface than the fugacity profiles of PAHs obtained by a passive sampler …”

“…35 Meanwhile, I(z) at C bulk = 100 μg L −1 (Figures 2B and S5) spiked with CTAB and FA to imitate field scenarios reveals much more subtle details near the air−water interface than the fugacity profiles of PAHs obtained by a passive sampler. 36 The maximum intensity at z = 0 (I(z = 0)) sharply decreases as C bulk decreases (Figure 2C). In addition, I(z = 0) decreases with increasing CTAB concentration and reaches a minimum (476 a.u.)…”

“…F s (z = d DL ), F s (z = 0), and F s (z = d SML ) are all linearly correlated with C bulk (Figure 4C), which is not unexpected because pyrene molecules freely diffuse in water, that is, the flux of pyrene varies linearly with the number of pyrene molecules. Based on this linearity, F s (z = 0) at C bulk = 10 ng L −1 , an environmentally relevant concentration, 36 can be extrapolated to be 300 ng m −2 d −1 (Table 1). This flux (300 ng m −2 d −1 ) should be taken with care as environmentally relevant concentrations (typically <10 ng L −1 ) are much lower than C bulk (1−100 μg L −1 ) used in the present study.…”

Near-surface distribution of pollutants in coastal waters as assessed by novel polyethylene passive samplers

“…Acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene and fluoranthene were proportion higher in the PS above the surface than below while the trend was the opposite for the 7 heaviest PAH. This directly relates to their volatility and has been previously observed in PE passive samplers (Ruge et al, 2015;Wu et al, 2016).…”

“…Passive samplers have been used for integrated measurements on both sides of the air-sea and sediment-water interfaces, principally for studying fluxes of contaminants (Ruge et al, 2015;Belles et al, 2016a). Recently, 4 to 7 passive samplers were used above and below the surface layer on a custom float to evaluate the profile of selected PAHS (Wu et al, 2016). Even though an accumulation of PAHs near the air-water interface was inferred, the roughness of the waves at the studied sites did not allow data collection of within 6 cm below or above the surface layer, preventing access to the actual SML.…”