Agriculture Reference
In-Depth Information
Reaction 1, or more specifically the concentra-
tion of NO
2
, greatly determines the amount of
O
3
produced (Seinfeld and Pandis, 2006). VOCs
are not a part of these three reactions, but they
play a critical role because they can oxidize NO
to NO
2
, thereby increasing the atmospheric con-
centration of NO
2
relative to NO. The ozone
forming potential (OFP) of each VOC can vary
widely, based in part on how the compound
reacts in the atmosphere and the rate at
which the compound undergoes the reaction(s)
(Carter, 1994). Therefore, the OFP of a given
VOC is important to consider when determin-
ing the environmental impact of its emission.
Table 9.2 lists some of the common VOCs emit-
ted from animal agriculture operations, their
sources and the maximum incremental reactivity
(MIR), which is a quantification of a compound's
ability to form O
3
developed by Carter (1994).
A larger MIR equates to a greater ability to drive
O
3
production.
Recent research has revealed that fer-
mented feeds (e.g. silage) seem to be a larger
on-farm source of VOCs than manure (fresh or
stored) as was previously assumed (Alanis
et al
.,
2008; Howard
et al
., 2010 a). Feedstuffs, such as
maize and lucerne, are often stored by farmers in
a way to encourage their fermentation as a way
to preserve those feeds for future use as a feed to
livestock. Storage for these feeds includes stave
silos, bunker silos and 'Ag Bags' (the feed is
placed in long, air tight plastic tubes that are
horizontal to the ground), and all systems are
most effective at producing high-quality feeds
when they are quickly filled and designed to
minimize exposure to the air. Emissions of VOC
from fermented feed are greater when the feed is
exposed to air, greater wind speeds and higher
temperatures (Montes
et al
., 2010).
Experiments both on-farm and in environ-
mental chambers have determined emissions of
VOC can originate from the manure on swine
and cattle production systems (Shaw
et al
.,
2007; Rumsey
et al
., 2012). Blunden
et al
.
(2005) collected air samples from sites down-
wind of swine farms in North Carolina and
found that acetone, acetaldehyde, methanol and
ethanol were the most prevalent VOCs found near
the hog barns. Rumsey
et al
. (2012) measured
VOC emissions from one North Carolina swine
farm from both the barn and the manure lagoon
over all four seasons. Lagoon VOC emissions
Table 9.2.
Some of the common volatile organic compound species emitted from animal agriculture
production and
their mean incremental reactivity (MIR) from Ca
rter (2009).
Compound
name
Chemical
formula
Livestock production
sources
MIR
References
Acetic acid
CH
3
CHOOH 0.66 Fermented feeds
Alanis
et al
., 2008
Fresh dairy cattle manure
Shaw
et al
., 2007
Enteric fermentation
Shaw
et al
., 2007
Acetaldehyde CH
3
CHO
6.34 Swine manure lagoon
Rumsey
et al
., 2012
Swine barn
Blunden
et al
., 2005; Rumsey
et al
., 2012
Fermented feeds
Howard
et al
., 2010a
Ethanol
CH
3
CH
2
OH
1.45 Dairy manure lagoon
Filipy
et al
., 2006
Fermented feeds
Howard
et al
., 2010a
Dairy cattle housing area
Filipy
et al
., 2006; Chung
et al
., 2010
Swine manure lagoon
Rumsey
et al
., 2012
Swine barn
Blunden
et al
., 2005; Rumsey
et al
., 2012
Methanol
CH
2
OH
0.65 Enteric fermentation
Shaw
et al
., 2007
Fresh dairy cattle manure
Shaw
et al
., 2007
Swine manure lagoon
Blunden
et al
., 2005; Rumsey
et al
., 2012
Swine barn
Rumsey
et al
., 2012
Acetone
CH
3
COCH
3
0.35 Dairy manure lagoon
Filipy
et al
., 2006; Chung
et al
., 2010
Dairy cattle housing area
Filipy
et al
., 2006; Chung
et al
., 2010
Swine manure lagoon
Rumsey
et al
., 2012
Swine barn
Blunden
et al
., 2005; Rumsey
et al
., 2012
