66
Pesticides, Organic Contaminants, and Pathogens in Air
4.7 Global Distribution and Climate Change
Atmospheric transport is a major route for transporting pesticides globally (Woodrow et al., 2018). In the tourist island of Pingan (Fujian Province,
China), seasonal variations in organochlorine (OC) pesticides correlated
with total particulate levels, which tend to be higher in winter and lower
in summer (Jiao et al., 2018). The source of the polluted air was traced to the
air mass from the “heating season” in Northern China, known to be laden
with particles. The same trend was observed in Jinan, China, from July 2009
to June 2010 for OC pesticides in particulate matter (Xu et al., 2011). High
concentrations of OC pesticides were detected in winter through spring
and were lower in summer. The long-range transport could be attributed to
seasonal usage as well as meteorological conditions.
In the Great Lakes region of the United States, pesticide levels in air were
greater in urban areas than in rural or remote sites, indicating pesticides in
the air can be attributed to agricultural use as well as other human activities
(Wang et al., 2018). Another study by the same group in the Great Lakes
region looking at both seasonal and spatial variation of gas particle partitioning again found that current-use pesticides were higher in urban areas.
Pyrethrins accounted for the high levels of atmospheric pesticides in urban
areas, while fungicides were highest in agricultural regions. Relative humidity and temperatures did not infuence vapor phase pesticides (e.g., trifuralin and chlorpyrifos), but the particle/aerosol phase of metolachlor was
marginally lower at higher humidity. While median levels of the current use
pesticides measured by Wang et al. (2018) were lower in remote regions, their
presence confrms transport to remote regions in which pesticides are not
intentionally applied.
Stable pesticides and stable degradates give important clues to the
long-range transport of POPs (e.g., DDT, toxaphene, chlordane, and lindane).
An expedition to the Arctic revealed higher relative levels of p, p′-DDT and o,
p′-DDT in east Asia and the North Pacifc indicating drift of recent use DDT
and related compounds on the adjacent content (Wu et al., 2011). Climate
change affected the distribution of enantiomers of α-hexachlorocyclohexane
(HCH) and the geometric isomers of chlordane in the Arctic (Bidleman et al.,
2015). Based on the ratios of γ-HCH to α-HCH, long-range transport is the
main contributing factor for atmospheric POPs in Antarctica (and not nearby
research stations) (Hao et al., 2019).
Global warming not only exacerbates the transport of pesticides and POPs
to remoter regions—through atmospheric movement and ocean currents, but
it also promotes secondary emissions of POPs from glaciers and permafrost
(Nadal et al., 2015; Wang et al., 2016; Bidleman et al., 2015). In addition to
POPs, other toxics like mercury are likely to be released from Arctic permafrost due to global warming (Schuster et al., 2018). To minimize the impact of
these climate changes, more research is needed.
Pesticides, Organic Contaminants, and Pathogens in Air
4.7 Global Distribution and Climate Change
Atmospheric transport is a major route for transporting pesticides globally (Woodrow et al., 2018). In the tourist island of Pingan (Fujian Province,
China), seasonal variations in organochlorine (OC) pesticides correlated
with total particulate levels, which tend to be higher in winter and lower
in summer (Jiao et al., 2018). The source of the polluted air was traced to the
air mass from the “heating season” in Northern China, known to be laden
with particles. The same trend was observed in Jinan, China, from July 2009
to June 2010 for OC pesticides in particulate matter (Xu et al., 2011). High
concentrations of OC pesticides were detected in winter through spring
and were lower in summer. The long-range transport could be attributed to
seasonal usage as well as meteorological conditions.
In the Great Lakes region of the United States, pesticide levels in air were
greater in urban areas than in rural or remote sites, indicating pesticides in
the air can be attributed to agricultural use as well as other human activities
(Wang et al., 2018). Another study by the same group in the Great Lakes
region looking at both seasonal and spatial variation of gas particle partitioning again found that current-use pesticides were higher in urban areas.
Pyrethrins accounted for the high levels of atmospheric pesticides in urban
areas, while fungicides were highest in agricultural regions. Relative humidity and temperatures did not infuence vapor phase pesticides (e.g., trifuralin and chlorpyrifos), but the particle/aerosol phase of metolachlor was
marginally lower at higher humidity. While median levels of the current use
pesticides measured by Wang et al. (2018) were lower in remote regions, their
presence confrms transport to remote regions in which pesticides are not
intentionally applied.
Stable pesticides and stable degradates give important clues to the
long-range transport of POPs (e.g., DDT, toxaphene, chlordane, and lindane).
An expedition to the Arctic revealed higher relative levels of p, p′-DDT and o,
p′-DDT in east Asia and the North Pacifc indicating drift of recent use DDT
and related compounds on the adjacent content (Wu et al., 2011). Climate
change affected the distribution of enantiomers of α-hexachlorocyclohexane
(HCH) and the geometric isomers of chlordane in the Arctic (Bidleman et al.,
2015). Based on the ratios of γ-HCH to α-HCH, long-range transport is the
main contributing factor for atmospheric POPs in Antarctica (and not nearby
research stations) (Hao et al., 2019).
Global warming not only exacerbates the transport of pesticides and POPs
to remoter regions—through atmospheric movement and ocean currents, but
it also promotes secondary emissions of POPs from glaciers and permafrost
(Nadal et al., 2015; Wang et al., 2016; Bidleman et al., 2015). In addition to
POPs, other toxics like mercury are likely to be released from Arctic permafrost due to global warming (Schuster et al., 2018). To minimize the impact of
these climate changes, more research is needed.