Assessing the Impact of Animal Waste Lagoon Seepage on the Geochemistry of an Underlying Shallow Aquifer
Dairy facilities and similar confined animal operation settings pose a significant nitrate contamination threat via oxidation of animal wastes and subsequent transport to shallow groundwater. While nitrate contamination resulting from application of animal manure as fertilizer to fields is well recognized, the impact of manure lagoon leakage on groundwater quality is less well characterized. In this study, a dairy facility located in the southern San Joaquin Valley of California has been instrumented with monitoring wells as part of a two-year multidisciplinary study to evaluate nitrate loading and denitrification associated with facility operations. Among multiple types of data collected from the site, groundwater and surface water samples have been analyzed for major cations, anions, pH, oxidation-reduction potential, dissolved organic carbon, and selected dissolved gases (CO{sub 2}, CH{sub 4}, N{sub 2}, Ar, Ne). Modeling of putative geochemical processes occurring within the dairy site manure lagoons shows substantial off-gassing of CO{sub 2} and CH{sub 4} in response to mineralization of organic matter. The gas ebullition appears to strip dissolved gases, including Ar and Ne, from the lagoon water leaving concentrations that are undersaturated with respect to the atmosphere. The resulting fractionated dissolved gas signature serves as an effective tracer for the lagoon water in the underlying shallow groundwater and can be used to constrain inverse geochemical models that assess mixing fractions of lagoon water and local groundwater water. Together with ion exchange and mineral equilibria reactions, identification of lagoon seepage helps explain key attributes of the local groundwater chemistry, including input and cycling of nitrogen, across the site.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 950064
- Report Number(s):
- UCRL-JRNL-219615; ESTHAG; TRN: US200910%%54
- Journal Information:
- Environmental Science and Technology, Vol. 41, Issue 3; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
ANIMALS
ANIONS
AQUIFERS
CARBON
CATIONS
CHEMISTRY
CONTAMINATION
DENITRIFICATION
DISSOLVED GASES
FERTILIZERS
GEOCHEMISTRY
ION EXCHANGE
MANURES
MINERALIZATION
MONITORING
NITRATES
NITROGEN
ORGANIC MATTER
OXIDATION
SURFACE WATERS
WASTES
WATER