Water, Sewage & Effluent November-December 2017 | Page 40

Diffuse pollution, the invisible threat Think pollution, and clogged streams and landfills come to mind. But there are invisible, less obvious culprits that poison rivers and water sources throughout the world. By Kim Kemp W What is diffuse pollution? Who better to answer the question than Brian D’Arcy, an independent environmental consultant who has worked for many years in environmental regulation and water pollution control. For about the past 15 years, his focus of involvement has been diffuse pollution and he is a recognised authority on the subject. “Diffuse pollution is the release of potential pollutants from a range of activities that, individually, may have no effect on the water environment but, at the scale of a catchment, can have a significant impact. Problems occur in both rural and urban environments and examples include urban storm water runoff into rivers; sulphur dioxide emissions to the air from fossil fuel combustion causing acid rain and acidification of lakes; and so too, nutrients and pesticides washing off vast tracks of farmland into surface water or, percolating down through the soil, into the groundwater,” he explains. The thing about diffuse pollution is that it is generally unintentional, he says, and adds: “For diffuse pollution, no-one gets out of bed to make a discharge to pollute the environment. You wash your car, you plough the hile the Organization for Economic Cooperation and Development (OECD) countries can boast decades of regulation and investment in wastewater treatment plants, producing gains for economies, human health, environment, and social values, the emerging and developing economies are yet to make such headway and there are still major problems from water pollution. Nestled in amongst all the obvious pollution s ources are invisible and indirect sources of water pollution, known as ‘diffuse pollution’. The use of pesticides in agriculture is one of the primary causes of diffuse pollution in groundwater and waterways generally. 38 Water Sewage & Effluent November/December 2017