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.     

Water Recreation and Risk

T his paper deals with concepts and methods that may be used in the assessment and management of risks associated with aquatic recreation. It aims to explore potential approaches and to indicate their strengths and weaknesses. The paper concentrates on hazards encountered in bathing, swimming and water-contact sports that may be affected by water quality. Aspects discussed include: the role of society in regulating risks that are taken voluntarily by individuals; the difficulties of measuring those risks by means of epidemiological studies; the questionable predictive power of bacterial indicators and the problem of finding a satisfactory rationale for determining the standards for recreational waters.     

Dynamic simulation of storm tanks

Storm retention tanks are used widely for regulating pollution caused by combined sewer overflows, a notably transient, dynamic phenomenon. Nevertheless, few dynamic models of the process have hitherto been proposed. A conceptual model for simulation of the dynamic performance of a storm tank is presented. Four modes of behaviour are identified: fill, draw, dynamic sedimentation and quiescent settling. Discussion is given of the problems associated with the model, in particular the characterization of spatial non-uniformities in pollutant concentrations. Simulation results are presented for the application of the model to a test storm disturbance based on field data taken from the Norwich Sewage Works in eastern England. The disturbance comprises the response of a sewer network to a high-intensity, short-duration precipitation event, with a significant transient increase in suspended solids concentration and a transient depression in ammonium-N concentration. The impact of the storm tank returns on primary clarifier performance is found to be almost negligible. Some tests of the sensitivity of the storm tank model to changes of its parameters, such as particle settling velocity, are discussed.     

Research into Health Risks at Bathing Beaches in Hong Kong

STandARDS FOR water quality at bathing beaches are intended to protect the health of swimmers. Until recently no reliable data were available on the relationship between pollution levels as measured by indicator bacteria and the actual level of risk to swimmers. The standard used in Hong Kong uses running median levels of E. coli but is relatively lax, reflecting the lack of alternatives to what are, in some cases, moderately polluted beaches. A prospective epidemiological study has been undertaken to determine what the risks are to swimmers in such circumstances and hence to determine the required level of pollution control. It has been established that there are higher rates of minor ailments among swimmers than among non-swimming control groups, and that the excess illness rates are pollution-related for most symptom categories, except eye symptoms. The best indicators were found to be E. coli , and staphylococci. The existing limit of acceptability applied in Hong Kong corresponds to a risk of 15 skin and gastrointestinal cases per thousand swimmers, a reasonably low rate but still a significant public health problem when multiplied by the very large number of swimmers using the beaches in Hong Kong every year.     

太湖流域“厂-站-网-河(湖)”一体化排水管理模式研究

“厂-站-网-河(湖)”一体化排水管理模式是近年来国内排水管理部门提出的一种排水管理模式,这种模式解决了排水管理责任主体分散、考核不清晰等问题,符合当前排水精细化、系统化整治要求,并纳入了部分省市污水处理、提质增效工作指导文件之中。太湖流域部分城市在“十三五”期间开展了排水一体化管理实践,取得了很好成效和经验。本文在一体化排水管理模式内涵和难点分析基础上,总结了苏州、常州、无锡等地管理经验,提出了太湖流域“厂-站-网-河(湖)”一体化排水管理模式,同时也给出了太湖流域未来排水一体化管理高水平发展的建议。     

Estimation of monthly diffuse nutrient loads for a watershed in Turkey

Diffuse pollution has a complex nature depending on various land‐use activities like agriculture, livestock breeding and forestry. In this study, an alternative methodology is applied for decreasing the spatial uncertainty of diffuse nutrient load estimations. It is applied in the Melen Watershed, Turkey, which is an important watershed from where additional water will be supplied for the megacity Istanbul via interbasin water transfer. Monthly diffuse nutrient loads were estimated for each subwatershed by utilizing remote sensing (RS) and geographical information systems (GIS). Estimated nutrient loads were considerably different in various months due to the temporally irregular fertilizer application and meteorological conditions. Temporal differences were also predicted in the spatial distribution of the nutrient loads. The methodology is applicable in watershed protection studies, especially where necessary etudes should be conducted in the short term and with limited data. Such efforts in identifying and determining the diffuse loads are important for sustainable management of the watershed.     

Upgrading Disinfection Installation in Strathclyde Region

I n 1984-85 S trathclyrde Regional Council Water Department received 108 EC Directive (80/778/ EEC) Article 20 Delays in Respect of Microbiological Parameters 57 and 58. This paper details the strategy which was adopted by the Department to complete the programme within a limited timescale, together with the associated costs. Plant performance data based on divisional and regional assessments are discussed, together with some ancillary information on trihalomethane production. Reference is also made to some public opposition to chlorination in remote areas on the grounds of aesthetic supply acceptability.