166
Pesticides, Organic Contaminants, and Pathogens in Air
Just like surface water measurements, precipitation measurements have
declined in recent years, so the majority of the data available were collected
prior to 2001. This makes it diffcult to determine how the concentrations are
changing over time. One study in Beijing, China, showed that precipitation
concentrations of TFA have increased dramatically over a decade (Zhai et al.,
2015). Precipitation monitoring sites in Canada have also seen increasing
concentrations between 1997 and 1999, although more recent data (2001 and
2002) are too sparse to make any conclusions. It would be expected that TFA
concentrations in precipitation would be higher now due to the elevated concentrations of HFC-134a and the introduction of HFO-1234yf, which forms
more TFA on a mole basis than HFC-134a.
TFA also appears in groundwater samples where the water arises from
recent infltration. TFA behaves in a similar fashion as chloride or bromide ions
in the soil (Richey et al., 1997): so it is fairly easily percolated into groundwater
from atmospheric or aquatic sources. Shallow groundwater samples in China
had similar concentrations of TFA as the surface water samples and rain samples (Chen et al., 2018), which also demonstrates the lack of permanent losses
of TFA passing through soil. Similar TFA concentrations between surface
waters and young spring water was also observed in Germany (Jordan and
Frank, 1999). TFA frequently appears in well water of recent origins (Xie et al.,
2020). In Switzerland, it was estimated that approximately 62% of the TFA in
the region was lost to groundwater while the remaining 38% was exported in
surface waters (Berg et al., 2000). Overall, TFA appears to be easily transported
to groundwater which is often used as a source of drinking water.
9.5.4 Terminal Waterbodies
The main concern with TFA is that its stability would allow it to accumulate
in terminal waterbodies that lack a water outfow. Precipitation and surface
water inputs would add TFA to these lakes. While the water can evaporate
from these lakes, the TFA cannot and so it remains behind, as a result of
evapoconcentration. After a period of years, the TFA concentrations would
rise to the concentrations that could impact aquatic organisms (Russell et al.,
2012; Tromp et al., 1995). These types of lakes tend to occur in arid regions that
have low precipitation and high evaporation rates. Despite the concern over
these terminal waterbodies, very little sampling has been conducted in these
ecosystems and all of the data predate the year 2000 (Table 9.6). The Dead Sea
in Israel had concentrations that were comparable to surface waters nearby
(Frank et al., 1996). In contrast, three lakes sampled in the United States had
elevated concentrations compared to the rivers fowing into them (Wujcik
et al., 1999). This implies that the TFA was building up in the ecosystem. It
was estimated that the observed lake concentrations represented between
4.2 and 13 years of inputs at the current rate. This sampling represents a time
period (1997) where HFC-134a emissions and atmospheric concentrations
were still relatively low. None of these lakes had any heavy industry in their
Pesticides, Organic Contaminants, and Pathogens in Air
Just like surface water measurements, precipitation measurements have
declined in recent years, so the majority of the data available were collected
prior to 2001. This makes it diffcult to determine how the concentrations are
changing over time. One study in Beijing, China, showed that precipitation
concentrations of TFA have increased dramatically over a decade (Zhai et al.,
2015). Precipitation monitoring sites in Canada have also seen increasing
concentrations between 1997 and 1999, although more recent data (2001 and
2002) are too sparse to make any conclusions. It would be expected that TFA
concentrations in precipitation would be higher now due to the elevated concentrations of HFC-134a and the introduction of HFO-1234yf, which forms
more TFA on a mole basis than HFC-134a.
TFA also appears in groundwater samples where the water arises from
recent infltration. TFA behaves in a similar fashion as chloride or bromide ions
in the soil (Richey et al., 1997): so it is fairly easily percolated into groundwater
from atmospheric or aquatic sources. Shallow groundwater samples in China
had similar concentrations of TFA as the surface water samples and rain samples (Chen et al., 2018), which also demonstrates the lack of permanent losses
of TFA passing through soil. Similar TFA concentrations between surface
waters and young spring water was also observed in Germany (Jordan and
Frank, 1999). TFA frequently appears in well water of recent origins (Xie et al.,
2020). In Switzerland, it was estimated that approximately 62% of the TFA in
the region was lost to groundwater while the remaining 38% was exported in
surface waters (Berg et al., 2000). Overall, TFA appears to be easily transported
to groundwater which is often used as a source of drinking water.
9.5.4 Terminal Waterbodies
The main concern with TFA is that its stability would allow it to accumulate
in terminal waterbodies that lack a water outfow. Precipitation and surface
water inputs would add TFA to these lakes. While the water can evaporate
from these lakes, the TFA cannot and so it remains behind, as a result of
evapoconcentration. After a period of years, the TFA concentrations would
rise to the concentrations that could impact aquatic organisms (Russell et al.,
2012; Tromp et al., 1995). These types of lakes tend to occur in arid regions that
have low precipitation and high evaporation rates. Despite the concern over
these terminal waterbodies, very little sampling has been conducted in these
ecosystems and all of the data predate the year 2000 (Table 9.6). The Dead Sea
in Israel had concentrations that were comparable to surface waters nearby
(Frank et al., 1996). In contrast, three lakes sampled in the United States had
elevated concentrations compared to the rivers fowing into them (Wujcik
et al., 1999). This implies that the TFA was building up in the ecosystem. It
was estimated that the observed lake concentrations represented between
4.2 and 13 years of inputs at the current rate. This sampling represents a time
period (1997) where HFC-134a emissions and atmospheric concentrations
were still relatively low. None of these lakes had any heavy industry in their