TRENDS IN ATMOSPHERIC N DEPOSITION SURROUNDING CLUSTERS OF LARGE ANIMAL FARMS IN THE UNITED STATES

We compared the spatiotemporal trends in precipitation NH4 and NO3 between HUC8 watersheds that presented spatial clustering and dispersion patterns of Concentrated Animal Feeding Operations (CAFOs). Nationwide, CAFO-clustered watersheds presented greater concentrations of precipitation NH4 (+100 ug/L) and NO3 (+ 600 ug/L) than CAFO-dispersed watersheds (p< 0.05). This relationship held true principally in Indiana, Oregon, and Pennsylvania for NH4 concentrations. NH4 concentrations increased from 1980 onward in CAFO-clustered watersheds in Pennsylvania while CAFO-dispersed ones presented significant negative temporal trends principally during spring. These seasonal trends may be associated with manure application techniques that vary by state, as well as climate differences.  In Wisconsin and Michigan, the concentrations of precipitation NO3 were greater in CAFO-clustered watersheds compared to CAFO-dispersed watersheds. We did not have CAFO-dispersed watershed representation in North Carolina for comparison, but we observed that watersheds with a higher density of CAFOs displayed an increasing trend in NH4 in CAFO-clustered watersheds, while no trend was observed in NH4 for watersheds with lower-density of CAFOs. These spatial and temporal patterns may be used to better understand N deposition dynamics in airsheds and bring insights into the role of CAFOs in freshwater nutrient pollution and harmful algal blooms expansion in the US.

Primary Presenter: Lorrayne Miralha, The Ohio State University (miralha.1@osu.edu)

Authors:

Lorrayne Miralha, The Ohio State University  (miralha.1@osu.edu)

Diane Lauritsen, LIMNOSCIENCES  (ddlauritsen@comcast.net)