Landfills and waste water treatment plants as sources of ... - GKSS

INTRODUCTION
1.4 Environmental concerns
1.4.1 Persistence
On the basis of today’s knowledge, ionic PFCs are not degradable in the environment
(Hekster et al. 2002). Due to its strong carbon-fluorine bond PFCAs and PFSAs are resistant
against oxidants, reductants, acids, bases, photolysis and metabolic processes (Schultz et al.
2003). In contrast, neutral PFCs are subject to biodegradation and atmospheric degradation
(Jensen et al. 2008). Metabolic transformation of FTOHs and FASAs to PFCAs and PFSAs
was observed in various studies (Dinglasan et al. 2004; Wang et al. 2009). Atmospheric
degradation by OH radical of neutral PFCs to persistent PFCAs and PFSAs was demonstrated
in several studies under laboratory conditions, mainly using smog chambers (Ellis et al. 2004;
Sulbaek Andersen et al. 2005; D'Eon et al. 2006; Martin et al .2006). In contrast to neutral
PFCs, ionic PFCs are removed from the atmosphere via dry and wet deposition (Hurley et al.
2003; Dreyer et al. 2010). On the basis of these processes, neutral PFCs are often named as
“precursor compounds” for persistent ionic PFCs.
Although it is often concluded that PBDE degradation is negligible and a rather slow process
(Vonderheide et al. 2008), photochemical and biological degradation in air, water, soils,
sediments and house dust have been reported (Eriksson et al. 2004; Gerecke et al. 2005; He et
al. 2006; Vonderheide et al. 2006). It is reported that photolysis is the predominant PBDE
degradation mechanism. For example, Raff and Hites (2007) estimated that about 90 % of low
molecular weight PBDEs are removed from the atmosphere by this process, whereas BDE209
is predominantly subject to wet and dry deposition. Nevertheless, the completely brominated
BDE209 is regarded as remarkable photolabile and tends to form lighter PBDEs in various
environmental compartments (Christiansson et al. 2009; Söderström et al. 2004; La Guardia et
al. 2007). Schenker et al. (2008b) estimated that about 50 % of the hexa- and heptaBDE
homologues in the environment originate from the debromination of decaBDE. However, the
contribution for tetra- and pentaBDE is distinctly lower. Moreover, oxidation of OH radicals
may also be of importance (Ueno et al. 2008). So far, there are two groups of PBDE
degradation products known. The first one are methoxylated PBDEs (MeO-PBDEs), that have
been detected in various marine biota, such as fish (Sinkkonen et al. 2004) and sea lions
(Stapleton et al. 2006). However, MeO-PBDEs can also have natural origin (Teuten et al.
2005). The second degradation products are hydroxylated PBDEs (OH-PBDEs), that have
recently been detected at elevated concentrations in surface water near to a WWTP (Ueno et
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