Partitioning of tetra‐ and pentabromo diphenyl ether and benzo[a]pyrene among water and dissolved and particulate organic carbon along a salinity gradient in coastal waters

Abstract

This study assessed the partitioning of 2,2',4,4'-tetrabromo diphenyl ether (BDE-47), 2,2',4,4',5-pentabromo diphenyl ether (BDE-99) and benzo[a]pyrene (BaP) among water, dissolved organic carbon (DOC: 4.93-8.72 mg/L), and particulate organic carbon (POC: 191-462 µg/L) along the salinity gradient (0-5.5‰) of the Baltic Sea off the coast of Finland. Equilibrium dialysis and two solid-phase extraction techniques using polyoxymethylene polymer (POM) were used to determine partitioning coefficients. Experiments using artificial coastal water (ACW) with Nordic fulvic (FAs) and humic acids (HAs) were used to assess the effect of salinity (0 and 5.5‰) on the DOC-water partitioning of the model compounds. All three compounds bound more (2.2-3.8-fold) to the HAs than to the FAs. Increasing salinity from 0 to 5.5‰ decreased sorption to dissolved humic substances in the ACW and Baltic Sea water samples. Along the salinity gradient, the sorption of compounds to organic material decreased when the salinity increased. Particulate organic matter sorbed model compounds per unit of carbon more than dissolved organic matter. Along the studied salinity gradient, the freely dissolved portion increased from 10 to 29% to 52 to 80% in the coastal water samples, mainly because of the increasing salinity and changes in DOC and quality of POC.

Projected future climate change and Baltic Sea ecosystem management

“…The distribution constant between water and DOC (log K DOC ) for hexachlorobenzene and phenanthrene, representing halogenated aromatic and polycyclic aromatic compounds, respectively, decreased from north to south in the Baltic Sea, while tributyl phosphate, representing compounds with polar functional groups and relatively high water solubility, showed no geographical variation. The salinity gradient in the study, from 2.8 to 6.6, probably had only a minor effect on the partitioning of the tested organic pollutants (Engebretson and von Wandruszka 1994 ; Kuivikko et al 2010 ). Considering the small variation of DOC concentration in the offshore Baltic Sea (4.2–5.2 mg C/l), we propose that differences in quality, i.e., the terrestrial component of the DOC, caused the differences in log K DOC values.…”

Aqueous photochemical degradation of BDE-153 in solutions with natural dissolved organic matter

“…Solutions of BDE-153, containing SRFA or PLFA, were prepared and exposed to simulated sunlight as detailed above. Experiments were conducted with addition of NaN 3 (10 mM, quenchers of 1 O 2 ) and IPA (100 mM, quenchers of OH) to investigate indirect photolytic mechanisms (Latch et al, 2003).…”

“…Leal et al (2013) reported that the photolytic percentage of BDE-209 decreased substantially in the presence of humic and fulvic acids and attributed their findings to two main effects: (i) screening effects from radiation absorption by humic substances and (ii) hydrophobic associations between BDE-209 and humic acid that promote quenching or deactivation of the excited-state. Further, humic substances affect the adsorption of organic contaminants to aquifer material and sorption of PBDEs to dissolved humic substances in aqueous solutions (Rav-Acha and Rebhun, 1992; Kuivikko et al, 2010). Chu et al (2005) attributed the decrease of the photolytic rate of PCBs, which have structural similarities to PBDEs, to the decrease in lifetimes of their excited singlet or triplet states caused by binding to humic substances.…”

“…BDE-153 solutions containing 10 mg L À1 NOM were studied under irradiation (l > 290 nm) in pure water, with the addition of IPA (100 mM, an OH scavenger) and NaN 3 (10 mM, an 1 O 2 scavenger) ( Fig. 3) (Latch et al, 2003). The addition of IPA in pure water induced a pronounced inhibition of BDE-153 photolytic rates in the presence of 10 mg L À1 NOM, indicating that OH was of importance in indirect photolytic processes.…”

Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants

“…Several methods have been developed to separate freely dissolved organic contaminants from DOM-bound species, including equilibrium dialysis, ultracentrifugation [8], reversephase separation, solid-phase microextraction [9], competing ligands [10], and ultrafiltration. For example, cross-flow ultrafiltration followed by gas chromatography-mass spectrometry has been used to determine the partitioning of organic contaminants between river colloids and the dissolved phase [11].…”