Carl Michael Stapleton

Faecal indicator organism concentrations and catchment export coefficients in the UK.

Characterisation of faecal indicator organism (FIO) concentrations and export coefficients for catchments with particular combinations of land use and under specific climatic regimes is critical in developing models to predict daily loads and apportion sources of the microbial parameters used to regulate water quality. Accordingly, this paper presents a synthesis of FIO concentration and export coefficient data for the summer bathing season, with some comparative winter data, for 205 river/stream sampling points widely distributed across mainland UK. In terms of both geometric mean (GM) FIO concentrations and export coefficients (expressed as cfu km(-2) h(-1)), the results reveal (1) statistically significant elevations at high flow compared with base flow, with concentrations typically increasing by more than an order of magnitude and export coefficients by about two orders; (2) significantly higher values in summer than in winter under high-flow conditions; and (3) extremely wide variability between the catchments (e.g. four orders of magnitude range for GM faecal coliform concentrations), which closely reflects land use-with urban areas and improved pastures identified as key FIO sources. Generally, these two most polluting land uses are concentrated in lowland areas where runoff (m3 km(-2) h(-1)) is low compared with upland areas, which in the UK are dominated by rough grazing and forestry. Consequently, contrasts in export coefficients between land use types are less than for FIO concentrations. The GMs reported for most land use categories are based on 13 sites and exhibit quite narrow confidence intervals. They may therefore be applied with some confidence to other catchments in the UK and similar geographical regions elsewhere. Examples are presented to illustrate how the results can be used to estimate daily summer base- and high-flow FIO loads for catchments with different land use types, and to assess the likely effectiveness of certain strategies for reducing FIO pollutant loadings in areas with extensive areas of lowland improved pasture.

Predicting microbial pollution concentrations in UK rivers in response to land use change

The Water Framework Directive has caused a paradigm shift towards the integrated management of recreational water quality through the development of drainage basin-wide programmes of measures. This has increased the need for a cost-effective diagnostic tool capable of accurately predicting riverine faecal indicator organism (FIO) concentrations. This paper outlines the application of models developed to fulfil this need, which represent the first transferrable generic FIO models to be developed for the UK to incorporate direct measures of key FIO sources (namely human and livestock population data) as predictor variables. We apply a recently developed transfer methodology, which enables the quantification of geometric mean presumptive faecal coliforms and presumptive intestinal enterococci concentrations for base- and high-flow during the summer bathing season in unmonitored UK watercourses, to predict FIO concentrations in the Humber river basin district. Because the FIO models incorporate explanatory variables which allow the effects of policy measures which influence livestock stocking rates to be assessed, we carry out empirical analysis of the differential effects of seven land use management and policy instruments (fiscal constraint, production constraint, cost intervention, area intervention, demand-side constraint, input constraint, and micro-level land use management) all of which can be used to reduce riverine FIO concentrations. This research provides insights into FIO source apportionment, explores a selection of pollution remediation strategies and the spatial differentiation of land use policies which could be implemented to deliver river quality improvements. All of the policy tools we model reduce FIO concentrations in rivers but our research suggests that the installation of streamside fencing in intensive milk producing areas may be the single most effective land management strategy to reduce riverine microbial pollution.

Estimated inorganic nutrient inputs to the coastal waters of Jersey from catchment and waste water sources

Abstract Concern over nutrient levels and eutrophication in the north-east Atlantic sea area has required a reduction in inputs at several urban centres. Implementation of a best European Practice by the States of Jersey has necessitated an assessment of the impact of the Islands waste water treatment works (WwTW) on inorganic nutrient inputs to the coastal zone. Inorganic nutrient concentrations in stream and sewage effluent inputs into St. Aubins Bay, Jersey, were monitored during the phytoplankton growing season. Inorganic nutrient input budgets were calculated using estimates of runoff based on hydrological data for an instrumented catchment. Results indicated that the WwTW accounted for 54% of the inorganic nitrogen load and 98% of the inorganic phosphorus load over the survey period. The remaining inputs from catchments are driven by the seasonality of flow and nutrient concentrations. Installation of nutrient removal technology at the WwTW would reduce the total inorganic nitrogen load by 33% and the inorganic phosphorus load by 86%. Implications for the WwTW and compliance with the European urban waste water treatment Directive 91/271/EEC are discussed.

Chapter 4:Impacts of Agriculture on Water-borne Pathogens

Microbial indicators of water quality are used to quantify the risk derived from faecally contaminated surface and drinking waters. The historical focus in this area has centred on human-derived sewage contamination of bathing, shellfish and drinking waters. However, emerging catchment-scale water legislation in North America and Europe, in particular, is driving a more holistic approach in which quantification of microbial pollution from all sources is undertaken, to inform and prioritise appropriate remedial action designed to ensure health risk is minimised. This involves integrated management of agricultural livestock-derived pollution alongside sewage effluents to ensure compliance of impacted sites with appropriate regulatory standards. The evidence-base for the design of best management practices by farmers which will remove and/or attenuate microbial flux from catchment systems is very limited when compared to the chemical parameters associated with ecological impairments, such as phosphorus and nitrogen. However, early empirical investigations do suggest the potential to realise very significant water quality benefits from simple interventions, such as stock exclusion fencing of stream banks and well-designed constructed wetland systems. Further process-based investigation of these areas is underway and this research effort is becoming imperative as emerging experience of catchment-scale legislation strongly suggests the importance of microbial pollution as the principal reason for non-compliance with water quality standards in North America.

Faecal Indicators and Pathogens: Expanding Opportunities for the Microbiology Community

Water regulation world-wide is moving to a new and challenging paradigm characterised by integrated assessment and management of multiple pollution loadings within drainage basins. This is seen in the European Water Framework Directive and the United States Clean Water Act. Implementation lessons of the latter suggest the principal water quality concern at the continental scale is microbial pollution by faecal indicators and pathogens. This presents a major new challenge to the microbiological community and presents major opportunities of joint working with catchment scientists, modellers, engineers and the farming community. To date, very little catchment-scale science has addressed microbial flux measurement, modelling and prediction when compared to other parameters such as the nutrients, oxygen demand and sediments. The engineering community has made excellent progress on point-source pollution control from sewage works but, parallel progress on agricultural best management practices to limit diffuse-source pollution from agriculture is less evident and the science evidence-base for the efficacy of such measures remains equivocal. This contribution presents a clear set of research challenges and management priorities designed to stimulate further involvement by the microbiological community in this emerging area.