John Crowther

Relationships between microbial water quality and environmental conditions in coastal recreational waters: the Fylde coast, UK.

This paper explores ways in which the analysis of microbial data from routine compliance monitoring, in combination with basic environmental data, can provide insight into the factors affecting faecal-indicator organism concentrations in coastal waters. In the case study presented, eight designated bathing waters on the Fylde coast are continuing to exhibit unreliable compliance with the Imperative standards for total coliform (TC) and faecal coliform (FC) concentrations specified in the EU Bathing Water Directive (76/160/EEC), despite significant reductions in geometric mean concentrations following recent major investment in the sewerage infrastructure. Faecal streptococci (FS) concentrations have remained high and have not been improved by the new sewerage schemes. The results suggest that, prior to the schemes, higher bacterial concentrations were strongly associated with rainfall; and sewage sources were important for TC and FC, but less important for FS, which may have been more strongly affected by diffuse catchment sources. In the post-schemes period, catchment sources appear to be of greater significance; rainfall remains as a significant, though less important, predictor; and tide height at time of sampling, together with variables such as sunshine and the proportion of onshore winds (which affect the survival and movement of bacteria that have already entered the coastal waters), assume greater significance. The approach used here provides a cost-effective management tool for the exploratory investigation of any monitoring point that is failing to meet recreational water quality standards.

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.

Modelling faecal indicator concentrations in large rural catchments using land use and topographic data

Aims: To characterize and model spatial variations in faecal‐indicator organism concentrations in watercourses draining a large rural catchment during the bathing season.

Faecal indicator impacts on recreational waters: budget studies and diffuse source modelling

A series of investigations are underway which have quantified the contribution of faecal indicators delivered to nearshore coastal waters from the sewerage system and riverine inputs. Studies have been completed in Jersey, Staithes, Yorkshire, South Wales and the North‐west. The resarch protocols have involved quantification of high and low flow faecal indicator delivery from the sewerage system and riverine sources as well as construction of nonpoint source models designed to predict faecal indicator delivery from diffuse, catchment sources. These investigations suggest a dynamic, but predictable, balance between inputs from the sewerage system and from ‘catchment’ sources. The sewerage system dominates during low flow conditions but is often overtaken by riverine inputs during high flow conditions after rainfall. Many bathing beach locations exhibit non‐compliance after rainfall when stream inputs, rather than sewerage inputs, commonly dominate. The implications of this input pattern is that routine monitoring data may not provide information relevant to new infrastructure planning designed to achieve bathing beach compliance. This suggests that the present scientific information base is insufficient to underpin the extensive UK infra‐structure investment programmes designed to ensure compliance with existing EU Directive 76/160/EEC standards. Furthermore, results to date, suggest that management attention must expand from its historical focus on infra‐structure provision to incorporate diffuse sources of faecal indicator loading which present a new set of management and modelling challenges.

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.

Short‐term, post‐burial change in a humic rendzina soil, Overton Down Experimental Earthwork, Wiltshire, England

The 1992 excavation of the Overton Down Experimental Earthwork provided a unique opportunity to study pedogenic change in a humic rendzina soil 32 years after burial beneath a chalk bank containing a central stack of turves. Investigations focused on soil structure, porosity, organic matter, plant remains, pH, carbonate, iron, and magnetic susceptibility. Standard methods of chemical analysis and micromorphological description were complemented by quantitative analysis of soil thin sections. The results demonstrate both the speed of change (e.g., compaction and organic decomposition have reduced the thickness of the Ah horizon by >50% in places), and the way the microenvironment of burial can significantly affect the nature and direction of change (e.g., differences in pH, carbonate, soil structure, and earthworm activity between soils buried beneath the chalk rubble and the central turf stack). These have important implications for the preservation of biological and cultural remains, and for the maintenance of their stratigraphic integrity.

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.