The impact of horse dung on urban groundwater quality in the Birmingham Triassic sandstone aquifer, UK

The aim of this study was to evaluate the role of pollution from horse dung (and urine) on groundwater quality in the UK Birmingham Triassic sandstone, an example urban aquifer. Urban horse populations were estimated for the period 1750 to 1970, interpolating where necessary using human and horse population statistics for other parts of the UK. Horse numbers increased from around 1000 in 1750 to a peak of around 12 000 in 1910, thereafter falling to <1000 by 1970. The waste produced would have been 100-200 x 10(3) t per year in 1910. Using data on dung (and urine) composition from the literature, and dung composition from leaching tests, chemical fluxes in recharge were estimated. It was concluded that on a regional scale the impact of horse wastes would have been a significant but not dominant input to some chemical balances. However, locally, considerable pollution would have occurred.