differences could be driven by differences in exposure concentrations; although
concentrations of organic contaminants in surface water were not often reported,
they were generally found at lower levels than for metals. Thus, in studies for which
concentrations in both biofilms and surface water were reported, all median
dissolved concentrations of metals were superior to 1 μg L
À1 (except for mercury),
while the median dissolved concentrations for all the organic contaminants studied
were below 1 μg L
À1 . Organic contaminants tend to get adsorbed to the organic
matter trapped in the biofilm, EPS, and cell membrane due to their specific chemical
properties and high lipid content (Wolfaardt et al. 1998; DeLorenzo et al. 2001;
Métivier et al. 2013). The bioaccumulation of organic contaminants in biofilms is
driven by their hydrophobicity, which can be estimated by their partition coefficient
between octanol and water, called log K ow (Fig. 6). Log K ow correlates positively
with the log BCFs of organic contaminants (Pearson correlation coefficient; n ¼ 70;
r
2
¼ 0.42, p < 0.05), and models have been developed to predict contaminant
bioaccumulation in biofilms based on physical-chemical properties (Ruhí et al.
−4
−2
0
2
4
5
0
log Kow
log(BCF)
DCPU
DCPMU
diuron
glyphosate
carbamazepine
diclofenac
diphenhydramine
gemfibrozil
venlafaxine
aroclor 1242
6:2 fluorotelomer sulfonate
linear perfluorooctanesulfonic acid
perfluorononanoic acid
perfluorodecanoic acid
perfluorohexane sulfonate
perfluoro−n−undecanoic acid
perfluorooctanoic acid
hexachlorobenzene
TBEP
Fig. 6 Bioconcentration factor, expressed as log(BCF) of organic contaminants in periphytic
biofilms vs. log K ow of the accumulated contaminants (n ¼ 70). Linear regression: log(BCF) ¼ 0.51 Ã
log K ow À 1.21 (r
2 ¼ 0.42, p < 0.01). Data from nine published studies. Data points circled in red are
observations from laboratory experiments; all other points are observations from field studies. DCPU N(3,4-dichlorophenyl) urea, DCPMU N-(3,4-dichlorophenyl)-N-(methyl) urea, TBEP tris(butoxyethyl)
phosphate
Role of Biofilms in Contaminant Bioaccumulation and Trophic Transfer in Aquatic. . .
129
concentrations of organic contaminants in surface water were not often reported,
they were generally found at lower levels than for metals. Thus, in studies for which
concentrations in both biofilms and surface water were reported, all median
dissolved concentrations of metals were superior to 1 μg L
À1 (except for mercury),
while the median dissolved concentrations for all the organic contaminants studied
were below 1 μg L
À1 . Organic contaminants tend to get adsorbed to the organic
matter trapped in the biofilm, EPS, and cell membrane due to their specific chemical
properties and high lipid content (Wolfaardt et al. 1998; DeLorenzo et al. 2001;
Métivier et al. 2013). The bioaccumulation of organic contaminants in biofilms is
driven by their hydrophobicity, which can be estimated by their partition coefficient
between octanol and water, called log K ow (Fig. 6). Log K ow correlates positively
with the log BCFs of organic contaminants (Pearson correlation coefficient; n ¼ 70;
r
2
¼ 0.42, p < 0.05), and models have been developed to predict contaminant
bioaccumulation in biofilms based on physical-chemical properties (Ruhí et al.
−4
−2
0
2
4
5
0
log Kow
log(BCF)
DCPU
DCPMU
diuron
glyphosate
carbamazepine
diclofenac
diphenhydramine
gemfibrozil
venlafaxine
aroclor 1242
6:2 fluorotelomer sulfonate
linear perfluorooctanesulfonic acid
perfluorononanoic acid
perfluorodecanoic acid
perfluorohexane sulfonate
perfluoro−n−undecanoic acid
perfluorooctanoic acid
hexachlorobenzene
TBEP
Fig. 6 Bioconcentration factor, expressed as log(BCF) of organic contaminants in periphytic
biofilms vs. log K ow of the accumulated contaminants (n ¼ 70). Linear regression: log(BCF) ¼ 0.51 Ã
log K ow À 1.21 (r
2 ¼ 0.42, p < 0.01). Data from nine published studies. Data points circled in red are
observations from laboratory experiments; all other points are observations from field studies. DCPU N(3,4-dichlorophenyl) urea, DCPMU N-(3,4-dichlorophenyl)-N-(methyl) urea, TBEP tris(butoxyethyl)
phosphate
Role of Biofilms in Contaminant Bioaccumulation and Trophic Transfer in Aquatic. . .
129