Reduced nutrient pollution in a rural stream following septic tank upgrade and installation of runoff retention measures

Ockenden, Mary and Quinton, John and Favaretto, Nerilde and Deasy, Clare and Surridge, Ben (2014) Reduced nutrient pollution in a rural stream following septic tank upgrade and installation of runoff retention measures. Environmental Science: Processes and Impacts, 16 (7). pp. 1637-1645. ISSN 2050-7887

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Abstract

Surface water quality in the UK and much of Western Europe has improved in recent decades, in response to better point source controls and the regulation of fertilizer, manure and slurry use. However, diffuse sources of pollution, such as leaching or runoff of nutrients from agricultural fields, and micro-point sources including farmyards, manure heaps and septic tank sewerage systems, particularly systems without soil adsorption beds, are now hypothesised to contribute a significant proportion of the nutrients delivered to surface watercourses. Tackling such sources in an integrated manner is vital, if improvements in freshwater quality are to continue. In this research, we consider the combined effect of constructing small field wetlands and improving a septic tank system on stream water quality within an agricultural catchment in Cumbria, UK. Water quality in the ditch-wetland system was monitored by manual sampling at fortnightly intervals (April - October 2011 and February - October 2012), with the septic tank improvement taking place in February 2012. Reductions in nutrient concentrations were observed through the catchment, by up to 60% when considering total phosphorus (TP) entering and leaving a wetland with a long residence time. Average fluxes of TP, soluble reactive phosphorus (SRP) and ammonium-N (NH4-N) at the head of the ditch system in 2011 (before septic tank improvement) compared to 2012 (after septic tank improvement) were reduced by 28%, 9% and 37% respectively. However, TP concentration data continue to show a clear dilution with increasing flow, indicating that the system remained point source dominated even after the septic tank improvement.

Item Type:
Journal Article
Journal or Publication Title:
Environmental Science: Processes and Impacts
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2300/2308
Subjects:
ID Code:
69014
Deposited By:
Deposited On:
28 Mar 2014 09:14
Refereed?:
Yes
Published?:
Published
Last Modified:
07 Jan 2020 04:01