ARS | Publication request: INFLUENCE OF VEGETATION IN RIPARIAN FILTERSTRIPS ON COLIFORM BACTERIA: I. MOVEMENT AND SURVIVAL IN SURFACE FLOW AND GROUNDWATER

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 23, 2000
Publication Date: N/A

Interpretive Summary: Land application of animal wastes is a means of disposing of the wastes and using them as a fertilizer to supply nutrients to crops. Animal waste contains many types of organisms pathogenic to humans and animals. Contamination of surface and groundwater resources by pathogenic bacteria poses a potential health hazard when animal waste is applied to agricultural lands in excess quantities. Liquid-waste discharge into soil follows natural ground water drainage patterns and may contaminate adjoining bodies of surface water. These same bodies of water are often used for sources of drinking water and for recreational activities. We monitored survival of total and fecal coliform bacteria in the pulse of applied wastewater, surface runoff, soil water at 0.5 and 1.0 m depths at 5, 10, 20 and 30 m from the inflow source, and shallow groundwater at 1.5 and 2.0 m depths at 5, 10, 20 and 30 m from the inflow source after application of swine wastewater. Total and fecal coliform numbers in the pulse of applied wastewater did not decline as water moved downslope regardless of vegetation type or season of the year. Total and fecal coliform numbers in soil water and shallow groundwater declined by approximately ten fold every 7 days for the first 14 days regardless of vegetative treatment or season. Total coliform bacteria in 1.5 and 2.0 m wells correlated with groundwater temperature and soil moisture in a curvilinear relationship (r squared = 0.89 and 0.89, respectively). Fecal coliform bacteria in 1.5 and 2.0 m wells also correlated with temperature and moisture in a curvilinear relationship (r squared = 0.82 and 0.76, respectively).

Technical Abstract: We applied swine wastewater to three separate 4m wide x 30 m long riparian filterstrips consisting of 20 m grass/10 m forest, 10 m grass/20 m forest and 10 m grass/20 m maidencane in Southern Georgia during each season of the year. We monitored survival of total and fecal coliform bacteria in the pulse of applied wastewater, surface runoff, soil water at 0.5 and 1.0 m depths at 5, 10, 20 and 30 m from the inflow source, and shallow groundwater at 1.5 and 2.0 m depths at 5, 10, 20 and 30 m from the inflow source after application of swine wastewater. Total and fecal coliform numbers in the pulse of applied wastewater did not decline as water moved downslope regardless of vegetation type or season of the year. The pulse of applied wastewater moved to 30.0 m in all treatments in the winter, and in the 20 m grass/ 10 m forest treatment in winter and spring. The pulse of applied wastewater did not move beyond 15 meters in any treatment in autumn or summer (dry seasons) and only moved beyond 7.5 m in the 20 m grass/ 10 m forest treatment in the summer. Total and fecal coliform numbers in soil water and shallow groundwater declined by approximately ten fold every 7 days for the first 14 days regardless of vegetative treatment or season. Total coliform bacteria in 1.5 and 2.0 m wells correlated with groundwater temperature and soil moisture in a curvilinear relationship (r squared = 0.89 and 0.89, respectively). Fecal coliform bacteria in 1.5 and 2.0 m wells also correlated with temperature and moisture in a curvilinear relationship (r squared = 0.82 and 0.76, respectively).