A six-month series of high-resolution synchronous stream discharge and total phosphorus (TP) concentration data is presented from a 5 km 2 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.

High-resolution measurements of total phosphorus (TP) concentrations in a stream draining a 5 km 2 agricultural catchment (a sub-catchment of Lough Neagh in Northern Ireland) were made every 10 mins by continuous flow instrumentation using new homogenisation, digestion and colorimetric phases. Concurrently, rainfall and stream discharge data were collected at 5 and 15 min. intervals. Major P flushing episodes during storm events peaked on the rising limbs of storm hydrographs. A period of baseflow also indicated the importance of other sources that maintain the stream in a eutrophic state between storm events. These data provide insights into catchment processes that conform to definite patterns that, in a coarser sampling regime, might ordinarily be attributed to sampling and analytical noise.

No abstract

No abstract

No abstract

Abstract. This study reports the use of high-resolution water quality monitoring to assess the influence of changes in land use management on total phosphorus (TP) transfers in two 5 km 2 agricultural sub-catchments. Specifically, the work investigates the issue of agricultural soil P management and subsequent diffuse transfers at high river flows over a 5-year timescale. The work also investigates the phenomenon of low flow P pollution from septic tank systems (STSs) and mitigation efforts -a key concern for catchment management. Results showed an inconsistent response to soil P management over 5 years with one catchment showing a convergence to optimum P concentrations and the other an overall increase. Both catchments indicated an overall increase in P concentration in defined high flow ranges. Low flow P concentration showed little change or higher P concentrations in defined low flow ranges despite replacement of defective systems and this is possibly due to a number of confounding reasons including increased housing densities due to new-builds. The work indicates fractured responses to catchment management advice and mitigation and that the short to medium term may be an insufficient time to expect the full implementation of policies (here defined as convergence to optimum soil P concentration and mitigation of STSs) and also to gauge their effectiveness.

Risks from emerging contaminants (ECs) in groundwater to human health and aquatic ecology remain difficult to quantify. The number of ECs potentially found in groundwater presents challenges for regulators and water managers regarding selection for monitoring. This study is the first systematic review of prioritisation approaches for selecting ECs that may pose a risk in groundwater. Online databases were searched for prioritisation approaches relating to ECs in the aquatic environment using standardised key word search combinations. From a total of 672, studies 33 met the eligibility criteria based primarily on the relevance to prioritising ECs in groundwater. The review revealed the lack of a groundwater specific contaminant prioritisation methodology in spite of widely recognised differences between groundwater and surface water environments in regards to pathways to receptors. The findings highlight a lack of adequate evaluation of methodologies for predicting the likelihood of an EC entering groundwater and highlights knowledge gaps regarding the occurrence and fate of ECs in this environment. The review concludes with a proposal for a prioritisation framework for ECs in groundwater monitoring which enables priority lists to be updated as new information becomes available for substances regarding usage, physico-chemical properties and hazards.

Flow responsive passive samplers offer considerable potential in nutrient monitoring in catchments; bridging the gap between the intermittency of grab sampling and the high cost of automated monitoring systems. A commercially available passive sampler was evaluated in a number of river systems encapsulating a gradient in storm response, combinations of diffuse and point source pressures, and levels of phosphorus and nitrogen concentrations. Phosphorus and nitrogen are sequestered to a resin matrix in a permeable cartridge positioned in line with streamflow. A salt tracer dissolves in proportion to advective flow through the cartridge. Multiple deployments of different cartridge types were undertaken and the recovery of P and N compared with the flow-weighted mean concentration (FWMC) from high-resolution bank-side analysers at each site. Results from the passive samplers were variable and largely underestimated the FWMC derived from the bank-side analysers. Laboratory tests using ambient river samples indicated good replication of advective throughflow using pumped water, although this appeared not to be a good analogue of river conditions where flow divergence was possible. Laboratory tests also showed good nutrient retention but not elution and these issues appeared to combine to limit the utility in ambient river systems at the small catchment scale.