Faecal-Indicator Budgets for Recreational Coastal Waters: A Catchment Approach

This paper explores the application of a catchment faecal-indicator budget approach to the examination of faecal-indicator sources impacting on coastal recreational water quality. This involves (i) the characterization of water quality in sewage effluent and riverine inputs, and (ii) measurement and estimation of input flows; the product of these components yields the input flux of indicator organisms from each source. The impact of sewage-treatment scenarios on budgets is also investigated.     

Developments in Health-Related Quality Standards for Chemicals in Drinking Water

Small differences in water quality standards can mean huge differences in costs for water treatment; difficulties which are compounded by standards for which the derivation is unclear, such as the EC drinking water Directive. Such situations give no indication of the margin of safety for a parameter or the significance to consumers of exceedances. The WHO Guidelines are being revised and will be presented so that the precise derivation of the numbers is absolutely clear. The scientific and quasi-scientific considerations can be separated and the user given the appropriate information to adapt the guidelines to particular circumstances. In deriving standards for toxicological data the factors incorporated reflect uncertainties in the data and extrapolation from animals to man. Understanding the mechanisms of toxicity or carcinogenicity can reduce the uncertainty and improve the quality of the standard, often allowing higher figures to be used with confidence that public health will not be comprised.     

The Application of Water-Quality Standards to UK Bathing Waters

Data for 425 sampling locations in England and Wales, covering the 1987 bathing season, were analysed against a range of six water-quality standards used by European and North American agencies. The following order of relative stringency was established: EEC guide level > US Environmental Protection Agency† > Toronto†> Canadian Federal† > Modified EEC standard > EEC imperative level†.
All European Community (EC) countries, at present abiding by the'imperative'bacteriological standards of the bathing waters Directive, would experience a significant increase in non-compliance for the faecal coliform parameter if standards were altered from the current EEC imperative criteria to any of the existing alternative beach management standards.     

Results of the First Pilot-Scale Controlled Cohort Epidemiological Investigation into the Possible Health Effects of Bathing in Seawater at Langland Bay, Swansea

A pilot study was conducted to investigate the feasibility of using adult volunteers to examine the possible health effects of bathing in UK seawaters which passed the EC bathing waters Directive. Langland Bay, near Swansea, was chosen for this experiment, which was conducted on 2 September 1989. Adult volunteers were recruited from the City of Swansea and randomly divided into bather and non-bather groups. All volunteers were given medical examinations and medical questionnaire interviews before and after 2 September.
Water quality on the day of the test was relatively unpolluted, as indexed by the commonly-employed bacterial and viral indicator species. The detailed medical questionnaire resulted in higher reported attack rates of perceived illness in both bather and non-bather groups than those published in previous studies, which have commonly employed a single telephone interview to acquire disease perception data. Statistically-significant differences in the bather and non-bather cohorts were found for the following perceived symptoms: sore throat, ear symptom, eye symptom at 3 d after 2 September, and for diarrhoea at three weeks after the experiment. The clinical tests employed failed to confirm these significant perceived symptom attack rate differentials.
The significance of these results is discussed in the context of previous research protocols to demonstrate the feasibility of this novel prospective controlled cohort approach for the acquisition of scientifically robust data on the health effect of recreational water use. If taken to a full-scale study, it is argued that this research protocol could offer considerable advantages over past methods and lead to scientifically valid water-quality standards for recreational waters.     

Three-Stage Treatment of Pennine Waters: The First Five Years

The first full-size three-stage water treatment works was built at Blackmoorfoot (near Huddersfield) just over six years ago. The three-stage treatment process involves flotation, first-stage filtration and subsequent manganese removal in three distinct stages. The works at Blackmoorfoot has been followed by several others in Yorkshire Water. This paper (a) describes the three-stage treatment process and its developments, (b) relates the operating experiences of the new works to date, and (c) gives some of the operating costs. The treatment process has been successful in treating upland Pennine waters and, as a result, water quality throughout the area has improved. The paper also shows that the process can be modified where water quality allows. The operating costs of the new process are affected by the economies of scale, but need not be greater than those of the older works which have been replaced.     

The computation and reporting of dissolved gas levels

Provisional standards are proposed for the computation and reporting of dissolved gas levels in freshwater and seawater. Total gas pressure should be reported in terms of excess pressure (ΔP). while component gases such as nitrogen, argon, oxygen and water vapor should be reported in terms of partial or excess pressure. Barometric pressure, dissolved oxygen, water temperature and salinity must also be reported.     

The Health Effects of Low-Contact Water Activities in Fresh and Estuarine Waters

Four studies were carried out at separate locations to investigate the relationship between health effects and low-contact water sports, and intensive microbiological sampling was conducted in parallel to the health studies at each site. The two sports examined were marathon canoeing and rowing.
The extremes of water quality were at the estuarine sites on the River Torridge, where pollution levels varied from a geometric mean faecal coliform value of 62/100 ml at the Appledore/Instow site to 4613/100 ml at the Bideford site.
A comparison of 'exposed' and 'unexposed' groups, 5–7 days after exposure, showed that the health effects of low-contact water sports are minimal, within the water quality ranges which were studied.     

城市景观水体水质维护的几种方法与实践

在国家高度重视发展节能环保型建筑的战略思路下,城市的生态化发展对城市景观水体的水质维护提出了新要求。文章列举工程实例介绍了目前国内外用于城市景观水体水质维护的主要工艺,并分析和比较了这些工艺在实际运用中的效果、适应性及运行成本等,肯定了加压溶气气浮法处理工艺在城市景观水体处理中的优势。     

Probabilistic environmental risk assessment of urban wet-weather discharges: an approach developed for Switzerland

Technical solutions aimed at limiting the impacts of urban wet-weather discharges are historically based on an end-of-pipe approach. The characteristics of wet-weather discharges, e.g. intermittent pollution loads, high variations in pollutant concentrations, effects in the receiving waters, etc., are generally not considered. This study presents a new probabilistic approach that links the characteristics of wet-weather discharges to their potential impacts in receiving waters. This new approach involves coupling a model for predicting fluctuating concentrations in rivers along with sediment changes to water quality criteria. The new approach produces a risk profile for receiving waters and includes assessment of uncertainty in input data as well as the uncertainty inherent in local receiving system processes. This new approach is expected to offer a better management of wet-weather discharges, resulting in lower environmental impacts.