Agriculture Reference
In-Depth Information
storage, with little degradation observed after
4.5 months of storage. Aeration accelerates hor-
mone degradation. Testosterone degraded at a
faster rate when swine manure was incubated
aerobically than in anaerobic conditions (Yang
et al
., 2010). Similarly, there are reports of
reduced oestrogen concentrations in poultry
and swine manure after aerobic composting
(Hakk
et al
., 2005; Derby
et al
., 2011). The con-
centration of E1 in composted swine manure
pile decreased and stabilized to <2 mg kg
−1
dry
weight after 36 days of storage, with a 94%
reduction in E1 by 92 days. In contrast, E1 in
un-composted manure decreased to a lesser
extent (>5 mg kg
−1
dry weight) and was not sta-
bilized at 36 days. After 92 days storage, the E1
concentration was reduced by 78% in static
manure. Total oestrogenicity was reduced by
79% and 74% in composted and static manure,
respectively, indicating the advantage of storing
manure before applying to the agricultural fields
(Derby
et al
., 2011).
Also, heat accelerates degradation. Zhao
et al
. (2010) reported that oestrogens were less
frequently detected in streams during summer
months and suggested rapid degradation of oes-
trogens in manure and soils at high tempera-
tures. Total oestrogens were reduced by 80% in
cattle faeces following 12 weeks of incubation at
20-23°C (Schlenker
et al
., 1998).
runoff. Because manure is land-applied rather
than discharged directly into waterways, the
likely risk of hormones from livestock farms
should be lower compared to hormones dis-
charged from wastewater treatment plants.
Oestrogens still have mobility to run off from
soil, however, and much more research is needed
on sorption of oestrogens and other steroid hor-
mones to agricultural soils.
Dairy manure
The presence of 17b-estradiol (3300 ± 700 ng l
−1
)
was reported in runoff from plots amended with
dairy manure (Dyer
et al
., 2001). The concentra-
tion in the runoff reached 41 and 29 ng l
−1
when
manure was applied at nitrogen or phosphorus-
based rate, respectively, 10-20-fold greater than
in runoff from plots without manure applica-
tion. Both free and conjugated oestrogens were
detected in barnyard runoff on a dairy farm
(Gadd
et al
., 2010). Among major free oestro-
gens, E2a was the most prevalent form followed
by E1 and E2b (110-11,000, 10-580 and
1-310 ng l
−1
, respectively). Conjugated oestro-
gens were present in almost all the samples. The
most prevalent oestrone-3-sulfate (12-180 ng l
−1
)
and less prevalent 17a-estradiol-3-sulfate and
17b-estradiol-disulfate (below detection limit
to 230 and 17-320 ng l
−1
, respectively) collec-
tively represented 8% of the total oestrogen
concentration.
Transport of oestrogen hormones through
soil to groundwater is suggested by detection of
E1 and E2b in the leachates from lysimeter soil
columns after application of dairy farm effluents
(Steiner
et al
., 2010). The major transport mech-
anism was with dissolved or suspended organic
matter (Laegdsmand
et al
., 2009) through pref-
erential/macropore flow pathways (Steiner
et al
.,
2010). Zhao
et al
. (2010) reported that most of
the oestrogens in liquid manure are associated
with the particles between 0.7 and 1.2 mm.
Fate of hormones in manure
following land application
When manure is land applied, some portion of
excreted hormones may enter water systems
through runoff or leaching (Nichols
et al
., 1997;
Finlay-Moore
et al
., 2000; Dyer
et al
., 2001;
Jenkins
et al
., 2006). All the hormones discussed
above are at least partially degraded following
land application of manure, to less active metab-
olites or all the way to CO
2
. Their half-lives vary
with the environmental matrix; half-lives of
hormones in manure and soil are longer than in
the aquatic environment. Temperature, mois-
ture, oxygen and pH all influence degradation of
steroidal hormones (Ying and Kookana, 2005).
Also important in evaluating risk to water
resources is that steroidal hormones may be
strongly sorbed to soil (Yu
et al
., 2004) and
sorption reduces the potential of leaching and
Poultry litter
One of the first reports that raised concern about
hormones from animal agriculture was with
land application of broiler litter (Nichols
et al
.,
1997). The 17b-estradiol concentrations in sur-
face runoff increased with increasing applica-
tion rate, reaching a maximum of 1280 ng l
−1
at
