Characterising phosphorus transfers in rural catchments using a continuous bank-side analyser

TLDR

The study aims to manage phosphorus transfers at the catchment scale by using robust monitoring technology to differentiate dynamic sources and event types, enabling reliable assessment of mitigation measures at catchment outlets. A six‑month, high‑resolution synchronous stream discharge and total phosphorus dataset was collected from a 5 km² agricultural catchment in the Lough Neagh basin, using hourly averages of 10‑minute measurements from a new bankside, automatic, continuous monitoring system. Three TP transfer event types were identified: chronic storm‑independent, acute storm‑dependent, and acute storm‑independent; the storm‑dependent events accounted for over 90 % of the 279 kg TP load, while the other two maintained eutrophication between storms and indicated point‑source pollution despite no major industrial inputs. Abstract.

Abstract

Abstract. A six-month series of high-resolution synchronous stream discharge and total phosphorus (TP) concentration data is presented from a 5 km2 agricultural catchment in the Lough Neagh basin, Northern Ireland. The data are hourly averages of 10-minute measurements using a new bankside, automatic, continuous monitoring technology. Three TP transfer "event-types" occur in this catchment: (1) chronic, storm independent transfers; (2) acute, storm dependent transfers; (3) acute, storm independent transfers. Event-type 2 transferred over 90% of the total 279 kg TP load in 39% of the total period; it corresponded to diffuse transfers from agricultural soils. Event-types 1 and 3, however, maintained the river in a highly eutrophic state between storm events and were characteristic of point source pollution, despite there being no major industrial or municipal point sources. Managing P transfers at the catchment scale requires a robust monitoring technology to differentiate between dynamic, multiple sources and associated event types and so enable a reliable assessment of the performance of mitigation measures, monitored at catchment outlets. The synchronous and continuous TP and discharge data series generated in this study demonstrate how this is possible.