Simulation of the redistribution and fate of contaminants from soil-injected animal slurry

Abstract

a b s t r a c tSpreading of contaminants from land-applied animal slurry may create hazard for both soil and water environments. Both the leaching and persistence of the contaminants is controlled by the redistribution of the contaminants immediately after application, while the redistribution is influenced by site conditions (here different slurry dry matter content and soil texture). HYDRUS-2D was used to simulate the redistribution of water, chloride, mineral N, Salmonella Typhimurium Bacteriophage 28B (phage), Escherichia coli, and steroid hormone estrogens near the slurry injection slit over a 50-day period after slurry injection at two field sites (Silstrup and Estrup) in Denmark to estimate the controlling transport and reaction parameters based on field measurements of the contaminants. The calibrated model was thereafter used to predict the leaching potential into the subsoil. The simulations confirmed that the higher water contents measured in the slurry application slit were due to a change in the hydraulic parameters. Chloride was redistributed considerably beyond the sampled soil profile at Estrup, but not at Silstrup, which had lower hydraulic conductivities than Estrup. Average size of the microorganisms affected their mobility; the bigger the size, the higher was the effect of the site conditions. The sorption coefficient of estrogens for slurry-amended soil was remarkably lower than that for unamended soil. The study suggests that dissolved organic carbon retained in slurry can facilitate the transport of contaminants. E. coli, phage, and estrogens were vulnerable to leaching from the very first precipitation event after the slurry application, whereas mineral N started to leach when NO 3 -N accumulated. Model predictions suggest that there are potential risks of leaching of these contaminants from the top soil to the subsoil associated with the land-injected slurry.

Seasonal persistence of faecal indicator organisms in soil following dairy slurry application to land by surface broadcasting and shallow injection

“…However, as this current study shows, injecting dairy slurry significantly increases the survival of FIOs in grassland environments compared to broadcast application, potentially sustaining a longer-lasting threat to surrounding water quality if these faecal sources are mobilised and transferred by subsequent rainfall run-off into artificial subsurface drainage systems, known to be efficient conduits of FIO transfer ( Oliver et al., 2005 ). Indeed, some research has highlighted vulnerability of FIO transfers following slurry injection ( Amin et al., 2014 ) and others have suggested that injection actually increases the leaching potential of nitrate, phosphorus and pathogens ( Fangueiro et al., 2014 ). Nevertheless, slurry injection of FIOs into the soil is likely to reduce the risk of ‘incidental’ rapid overland flow losses from land to water following heavy rainfall because the slurry is better protected from detachment mechanisms such as raindrop impact on the soil surface.…”

Modelling Water Flow and Escherichia coli Transport in Unsaturated Soils Under Drip Irrigation

“…According to knowledge of the longitudinal and transversal dispersivities ( D L and D T ) (Wang, ; Amin et al, ), we used D L = 6 cm and D T = 1 cm for the sandy soil and D L = 12 cm and D T = 1 cm for the sandy loam soil. Molecular diffusion ( D w ) involved in the simulation was determined according to the values reported by Ford and Harvey ().…”

Yield of three newly developed mustard varieties as affected by irrigation at different growth stages

“…The description of the simulation process is brief here because it was not the main focus of the study. This type of simulation study using HYDRUS model has been described in Amin et al (2014).…”