Groundwater Quality Changes Resulting from a Surface Bromide Application to a Pasture

Abstract

AbstractPotassium bromide was applied at a rate of 168 kg Br−/ha to two 1.1‐ha pasture watersheds in east‐central Ohio to study the impacts on groundwater quality of a one‐time application of a soluble constituent. The watersheds had well‐drained residual silt loam soils and average slopes of about 20%. A nearly impermeable clay layer under the watersheds created a perched aquifer from which groundwater samples could be taken at developed springs. Three monolith, grassed lysimeters having soil profiles similar to the watersheds also received the Br−1 treatment. The lysimeters, which were 8 m2 in surface area and had a depth of 2.4 m, had shorter leaching pathways than the watersheds and showed peak Br−1 concentrations in percolation (24.0 mg/L maximum peak) occurring 52–78 weeks following the Br−1 application. The Br−1 concentration in the groundwater from the watersheds had lower peaks (9.2 mg/L maximum peak) but occurred 84 to 104 weeks after the Br−1 application. Because of variable leaching pathway lengths, including pathways much longer than those in the lysimeters, the watershed groundwater Br−1 applications had shown no meaningful decrease by 2 yrs after the Br−1 application. A one‐time application of a soluble, nondegradable chemical constituent can have a multi‐year influence on groundwater quality.