HR: 1340h
AN: H43B-0372    [Abstracts]
TI: Geochemical Impacts of CAFOs: Implications for Modifying Existing Regulatory Standards in Michigan
AU: * Borrello, M C
EM: Borrello@alma.edu
AF: Alma College, 614 W. Superior Street, Alma, MI 48801 United States
AU: Oemke, M P
EM: Oemke@alma.edu
AF: Alma College, 614 W. Superior Street, Alma, MI 48801 United States
AU: Snowdon, L
EM: lissa320@aol.com
AF: Alma College, 614 W. Superior Street, Alma, MI 48801 United States
AU: Farley, A
EM: aafangel06@hotmail.com
AF: Alma College, 614 W. Superior Street, Alma, MI 48801 United States
AB: Concentrated Animal Feeding Operations (CAFOs), those facilities consisting of 1000 + cattle or hogs, are increasingly among the most significant sources of agricultural contamination in many surface waters in Michigan and around the country. Many environmental and rural citizens' groups argue that Michigan law controlling CAFO operations has been inadequate in dealing with the large volume of nutrient loading observed in streams. Stream impacts due to CAFOs have been measured using the same traditional biological and geochemical parameters as those used to assess general agricultural runoff. Geochemical parameters used include: total nitrogen, nitrate and ammonia, total phosphorous, dissolved oxygen (DO) and conductivity. These parameters are used not only as indicators of stream impact in agricultural states such as Michigan and Indiana but also provide the basis for regulatory standards. This study focused on two large CAFOs in which samples were taken in agricultural drains upstream and downstream from known, historic discharges of these facilities. Traditional analyses of total nitrogen and total phosphorous showed only subtle differences when comparing the upstream and downstream sites. Differences in DO were more pronounced between the sites (consistently lower for the downstream locations) but did not offer a direct correlation with presumed CAFO impacts. Other results, however, suggest that it is possible to isolate CAFO impacts by comparing transient chemical constituents such as (inorganic) orthophosphate and ammonia and by plotting these comparisons against DO. Ammonia concentrations plotted against orthophosphate displayed moderate to strong correlation (r = 0.84) for downstream sites but weak correlations (r = 0.04) for upstream sites. Ammonia and nitrate concentrations correlated strongly for downstream sites (r = 0.58) but weak for upstream sites (r = 0.09). Also, 24 hour DO analyses of all the sites indicated higher fluctuations throughout the day but only for the upstream sites. DO appeared to correlate strongly with orthophosphate concentrations (r = 0.68) for the downstream sites as compared with upstream site correlations (r = 0.058). If new laws and/or guidelines are to be established that adequately address and mitigate potentially negative impacts on surface water from CAFOs, a method of geochemical assessment has to be developed that will isolate CAFO impacts from general agricultural influence. The results of this study suggest that traditional means of assessing agricultural runoff in surface waters are inadequate in determining short and long-term CAFO impacts on surface water quality. Subtle differences do occur using traditional geochemical parameters, but using these parameters alone are insufficient and ineffective in providing a definitive assessment of CAFO impacts relative to the impacts that already exist. What may be needed is a greater focus on the short-term geochemical relationships between parameters such as ammonia, orthophosphate and dissolved oxygen. State and federal guidelines regulating CAFO facilities may need to incorporate these types of analyses in order to better assess future impacts.
DE: 4825 Geochemistry
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
DE: 0345 Pollution--urban and regional (0305)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting