Groundwater is vulnerable to pollutants that leach from the land surface.
Diffuse pollution comes from non-point source, widespread activities within the current and past agricultural and urban environments.
There is also a contribution from atmospheric deposition.
Rural diffuse pollution arises from land use activities spread across large areas, such as:
Dispersed housing may also be a source. The pollutants of concern have included the nutrients nitrogen (typically in the form of nitrate) and phosphorus, pesticides, biodegradable substances, ammonia and micro-organisms, such as faecal coliforms.
In urban areas, both industrial and municipal activities generate pollutants.
Urbanisation changes the natural pattern of recharge to groundwater with run-off from built areas and impervious surfaces, such as roads and car parks, and input from mains water, leaking sewers and pluvial drains.
Infiltration may carry a mix of polluting substances, such as toxic metals, pesticides, oils and hydrocarbons, sediments and oxygen-depleting substances.
Recently advancing analytical techniques have identified a range of widespread emerging contaminants in groundwater, including pesticide breakdown products, pharmaceuticals, food additives, industrial compounds and caffeine and nicotine.
Rueedi, J, Cronin, A A, and Morris, B. 2009. Estimation of sewer leakage to urban groundwater using depth-specific hydrochemistry. Water and environment journal, 23 (2). 134–144.
Morris, B, and Cunningham, J. 2008. Suburbanisation of important aquifers in England and Wales: estimating its current extent. Water and environment journal, 22 (2). 88–99.
Morris, B L, Darling, W G, Cronin, A A, Rueedi, J, Whitehead, and E J, Gooddy, D C. 2006. Assessing the impact of modern recharge on a sandstone aquifer beneath a suburb of Doncaster, UK. Hydrogeology Journal, 14 (6). 979–997.
Contact Marianne Stuart for further information