Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2012
Publication Date: 8/1/2012
Citation: McLaughlin, M.R., Brooks, J.P., Adeli, A. 2012. Temporal flux and spatial dynamics of nutrients, fecal indicators, and zoonotic pathogens in anaerobic swine manure lagoon water. Water Research. 46:4949-4960.
Interpretive Summary: This study increased our knowledge of the distribution of nutrients and bacteria, including pathogens, in anaerobic swine manure lagoon effluent, which is a valuable fertilizer resource. Changes in time and space were documented over a 14-month period in an 8-acre lagoon in the Mid-South. Nutrient levels were higher in deeper samples than near the surface. Some differences observed over time were linked with environmental factors, such as increasing E. coli levels with increasing lagoon effluent pH, increasing losses of nitrogen and inorganic carbon (probably as ammonia and greenhouse gas emissions) as lagoon temperature increased above a threshold of 19°C (66°F), decreasing populations of Campylobacter spp., enterococci, Listeria spp., and Salmonella spp. with increasing lagoon temperature, and higher levels of water-soluble heavy metals (Cu, Fe, and Zn) with increasing lagoon temperature. Declining levels of nitrogen during the summer irrigation season affected N:P ratios, raising concern for excess P applications to crop land irrigated with effluent later in the season. Frequent testing of effluent nutrient levels and periodic review and revision of nutrient management plans are indicated. Results from the study will enable better informed, safer, and more efficient use of lagoon effluent in the region.
Technical Abstract: Swine (Sus scrofa domestica) manure management in confined animal feeding operations (CAFOs) in the Mid-South US involves anaerobic lagoons. Lagoon effluent is used to irrigate and fertilize crops. Nutrients and bacteria in effluent have been sporadically characterized, but annual temporal changes were unknown. The objectives of this study were to assess nutrient and bacterial levels at different times and depths in a 3.2 ha lagoon for 1 year. Environmental conditions were monitored. Effluent was analyzed for pH, electrical conductivity (EC), inorganic (i) and organic C, total N, water soluble (ws) and total (t) Ca, Cu, Fe, K, Mg, Mn, P, and Zn and for Escherichia coli (Migula) Castellani and Chalmers, enterococci, Clostridium perfringens (Veillon and Zuber) Hauduroy et al., Campylobacter spp., Listeria spp., Salmonella spp., and staphylococci. All parameters showed significant temporal differences. Levels of organic C, tCa, tCu, tFe, tMg, tMn, tP, TZn, and C. perfringens were higher in deep (1.0 m) than shallow (4 cm) samples. No temporal-spatial interactions occurred. E. coli levels increased as pH increased, and Campylobacter spp., Listeria spp., Salmonella spp., and enterococci levels decreased while wsCu, wsFe, and wsZn increased as temperature increased. Changes in tN and iC were fitted to regression models with lagoon temperature deviation from 19°C. Levels increased below this threshold and decreased above it. During the irrigation season tN and iC decreased by half and N:P changed from 9.7 to 2.8. These results document temporal and spatial differences in nutrient and bacterial levels in effluent and enable more efficient management and use of this resource.