Bovine faecal contamination in an Irish agricultural catchment: sources and pathways

Abstract

Agricultural impacts on surface waters have been an intensive source of contamination on freshwaters worldwide. Faecal contamination is one of the most under regulated and poorly understood pollutants within Irelands surface waters, despite is widely recorded ability to cause harm to both animals and the environment. Creating novel solutions to help rectify the negative effects of poor agricultural management is necessary for protecting the future health if Irelands waters. Although current policy under the European Union (EU) provides guidelines and regulations, Ireland has still failed to contain its faecal contaminant issue. The solution to this dilemma may lie in the origins of this pollutant; current research demonstrates Irelands agriculturally dominated catchments could be suffering from point source dissemination of contaminants via input through farmyards and direct cattle access to streams. This dissemination model differs from the current non point source model that the EU and Irish policies implicitly endorse. This study’s objectives were as follows; to quantify the ability of headwater drainage channels receiving direct farmyard effluent to attenuate faecal indicator organisms (thermotolerant coliforms) within the water column and within benthic sediments, over their length; and to determine the distribution, concentration, and origin of thermotolerant coliforms (TTC’s) at intensive spatial scales within in a small agriculturally dominated catchment in South West Ireland. Utilizing novel colonization substrata, results demonstrated no trends of attenuation within headwater drainage areas; subsequent data provided TTC concentration and distribution within the larger drainage catchment upon deposition from the previously studied channels. Results from catchment wide analysis demonstrated a definitive connection to faecal contamination of point source origin from farmyards as well as direct deposition from cattle access to streams. The future of faecal contamination management within Irelands waters lies within the exploration of novel and established treatment methodology in order to create effective overarching policy changes.