Environmental Engineering Reference
In-Depth Information
Algal toxins are produced during algal or cyanobacterial blooms in natural
waters (Richardson and Ternes
2011
; dos Anjos et al.
2006
; Wood et al.
2006
;
Zhao et al.
2006b
; Smith et al.
2011
).
Emerging pollutants can be altered in the environment by direct and indirect
photolysis, hydrolysis, other chemical processes, biodegradation, sorption, vola-
tilization and dispersion, or by a combination of these processes. Environmental
transformation can either contribute to the complete removal of the organic con-
taminants, or produce transformation intermediates that can sometimes occur
in the environment at higher levels than the parent compound and that can be as
toxic or more toxic (Scully et al.
1988
; Jensen and Helz
1998
; Jameel and Helz
1999
; Mitch et al.
2003
; Strynar and Lindstrom
2008
; Boxall et al.
2004
; Gurr and
Reinhard
2006
; Jahan et al.
2008
).
8.2 Transport of Emerging Contaminants in the Aquatic
Environment
Once released into the environment, emerging contaminants are transported into dif-
ferent aquatic organisms, sediments and plants, depending on the emission routes as
well as their physico-chemical properties such as water solubility, vapor pressure and
polarity (Guo et al.
2009
; Richardson and Ternes
2011
; Daughton and Ternes
1999
;
Farré et al.
2008
; Epel and Smital
2001
). Emerging contaminants are generally per-
sistent, have a wide range of hydrophilicity/hydrophobicity, and many of them are
liable to bioaccumulation and biomagnification in organisms and plants when present
in the aquatic environment (Guo et al.
2009
; Richardson and Ternes
2011
; Daughton
and Ternes
1999
; Farré et al.
2008
; Epel and Smital
2001
). Aquatic organisms includ-
ing fish can accumulate emerging contaminants in certain body tissues. This phe-
nomenon can take place either directly by bioaccumulation and biomagnification
from water or by uptake of food such as OM (e.g. algae), sediments in water bed,
small aquatic plants and so on, which have come in contact with the contaminants.
Emerging contaminants are mostly transmitted to humans through food con-
sumption, particularly fish and seafood (Wong et al.
2002
; Meng et al.
2007
).
Synthetic musks are potential candidates as substrates or inhibitors of multixeno-
biotic resistance (MXR) transporters (Daughton and Ternes
1999
; Epel and Smital
2001
). The multixenobiotic resistance (MXR) in aquatic organisms is mediated
by the transport activity of transmembrane proteins belonging to the ATP-binding
cassette (ABC) superfamily. These proteins are primarily involved in the active,
ATP-dependent transport of biological molecules across plasma membranes
(Smital et al.
2004
; Higgins et al.
1988
; Dean et al.
2001
). The P-glycoprotein
(P-gp) detected in ABC can transport drugs, xenobiotic compounds, antican-
cer agents including the vinca alkaloids and anthracyclines, drugs against human
immunodeficiency virus (HIV), fluorophores as well as typical environmental pol-
lutants (Smital et al.
2004
; Danø
1972
; Juliano and Ling
1976
; Smital and Kurelec
1998
; Bard
2000
; Litman et al.
2001
). Various transmembrane transport proteins
