Thomas Claßen

Microbial Load of Drinking Water Reservoir Tributaries during Extreme Rainfall and Runoff

ABSTRACT Hygienic and microbiological examinations of watercourses are usually not carried out during heavy rainfall and runoff events. After rainfall or snowmelt, there are often massive increases in turbidity in flooding creeks in mountain ranges, which are frequently interpreted as an indication of microbial contamination. The aim of this study was to quantify the microbial loads of watercourses during such runoff events and to compare these loads with loads occurring during regular conditions. In a 14-month monitoring period we investigated the microbial loads of three tributaries of different drinking water reservoirs. A total of 99 water samples were taken under different runoff conditions and analyzed to determine physical, chemical, bacterial, and parasitic parameters. Thirty-two water samples were considered event samples during nine measuring series. The criteria for events, based on duration and intensity of precipitation, water depth gauge measurements, and dynamics, had been fixed before the investigation for each creek individually. Of the physical and chemical parameters examined, only the turbidity, pH, and nitrate values differed clearly from the values obtained for regular samples. Most of the bacteriological parameters investigated (colony, Escherichia coli, coliform, fecal streptococcal, and Clostridium perfringens counts) increased considerably during extreme runoff events. If relevant sources of parasitic contamination occurred in catchment areas, the concentrations of Giardia and Cryptosporidium rose significantly during events. The results show that substantial shares of the total microbial loads in watercourses and in drinking water reservoirs result from rainfall and extreme runoff events. Consequently, regular samples are considered inadequate for representing the microbial contamination of watercourse systems. The procedures for raw water surveillance in the context of multiple-barrier protection and risk assessment ought to include sampling during extreme runoff situations.

Contributions of Natural Environments to Physical Activity : Theory and Evidence Base

The link between modern lifestyles and increasing levels of chronic heart disease, obesity, stress and poor mental health is a concern across the world. The cost of dealing with these conditions pl ...

A comparison of efficiencies of microbiological pollution removal in six sewage treatment plants with different treatment systems

Six sewage treatment plants (STP) were investigated over a 12-month period in order to measure the microbiological load of untreated municipal wastewater and to evaluate the removal efficiencies of different treatment systems. The STP investigated can be classified into three categories: bigger plants with tertiary treatment, smaller plants with enhanced secondary treatment, and very small compact facilities. The plants studied had a considerable quantitative impact on the hydrology of the catchment area; consequently, it was anticipated that the microbiological load of the effluent would also be significant. Eighty samples were taken from the influent and effluent of the STP, regardless of weather conditions, and several bacterial and two parasitological parameters were analysed. The average microbiological reduction of each STP was dependent on its capacity and treatment procedures and varied between 1.9 and 3.5log10. Small compact facilities had a significantly lower removal efficiency (2.0+/-1log10) and discharged treated wastewater with a poorer microbiological quality compared to larger plants with tertiary treatment or with enhanced secondary treatment (2.8log10). Final sand filtration and extensive intermediate settling considerably improved the overall microbiological removal efficiency. During the study period, the microbiological water quality of the receiving water course was not significantly impaired by the discharge of any of the investigated plants; however, the compact facilities showed critical treatment deficiencies. In particular, the reduction of Giardia cysts was insufficient (<1.5log10) compared to that of the bigger plants (>3.0log10). In order to quantify the overall impact of microbiological loads on the receiving watercourse in this catchment area, it is also necessary to assess the pollution from combined sewer overflow basins and diffuse pollution. This will be considered in subsequent studies.

Effect of sewage treatment plants and diffuse pollution on the occurrence of protozoal parasites in the course of a small river.

In Germany, protozoal parasites are detected frequently in surface waters. This study aims to assess the parasitological pollution in a river course and two of its tributaries under regular weather conditions. Cryptosporidium was detected in 67% of all samples. The median concentration was 4 oocysts/100l. Giardia lamblia were detected in 90% of the samples. The median concentration of G. lamblia was 22 cysts/100l and increased significantly following the river course. A statistically significant correlation was found between both parasites and the faecal indicators Clostridium perfringens and Escherichia coli. The intermittent occurrence of Cryptosporidium in the streams investigated was ascribed primarily to diffuse pollution, particularly during rainfall events. The relatively frequent detection of G. lamblia derived mainly from sewage treatment plants. The pathogen concentrations observed present a relevant public health risk as the river is used for recreational activities and agricultural purposes.

Contributions of Natural Environments to Physical Activity

The idea that nearby nature stimulates people to be more physically active is quite popular. In this chapter the literature regarding the link between physical activity and the residential environment is scrutinized. More specifically, after introducing the main concepts and a theoretical framework the evidence regarding three categories of activity is examined: physical activity in general, walking and cycling (mainly by adults), and outdoor play by children. Overall activity is deemed important because of its link to total energy expenditure, and thereby health. However, the other two categories are more likely to be linked to green aspects of the environment. Also attention is paid to the possibility that activity undertaken in a natural environment is especially beneficial for one’s health. At the end of the chapter conclusions are summarized, directions for future research are proposed and policy recommendations are given, as far as possible given the current state of affairs.

Two decades of system-based hygienic–microbiological research in Swist river catchment (Germany)

A multidisciplinary research project series has sought to identify and better understand multiple hygienic–microbiological and chemical contaminations from both point sources and diffuse pollution to contribute to the improvement in surface water quality. In the catchment area of the river Swist (Germany), municipal sewage treatment plants were investigated, followed by event-based investigation of combined sewer overflows, rainwater retention basins and diffuse pollution by surface and subsurface run-off as well as drain pipes. Recently, retention soil filters installed between stormwater storage basins and receiving surface waters in order to provide further treatment of combined sewer overflows were investigated. Geographical information system analysis helped to examine the data in their temporal and spatial dimensions. A model for calculating microbial and chemical loads within a catchment area was developed (“Swistbox”) which provides an efficient tool for risk assessment. Nearly two decades of investigation has demonstrated that several elements of the landscape’s water balance account for surface water pollution from both diffuse and point sources. Depending on land cover characteristics, wastewater technology and the proportion of wastewater as compared to total river water flow, a source can vary in its importance for the catchment area. The findings can be applied for sustainable and health-sensitive catchment management in relation to recreational or agricultural water use as well as ecological aspects.

Gesundheitsrisiko Klimawandel: eine lösbare Aufgabe für Regionen und Kommunen?!

Innerhalb der letzten zwei Jahrzehnte haben die internationalen Strategien und Masnahmen fur einen aktiven Klimaschutz und die Reduzierung der komplexen gesundheitsgefahrdenden, okonomischen und okologischen Effekte des globalen Klimawandels nur beschrankte Wirkung gezeigt. Angesichts des fortschreitenden Klimawandels traten vermehrt zusatzliche Strategien zur aktiven Anpassung an den Klimawandel in den Fokus. 2008 hat die deutsche Bundesregierung die Deutsche Anpassungsstrategie an den Klimawandel verabschiedet, die Masnahmen beinhaltet, die sich mit den verschiedenen Auswirkungen des Klimawandels und den daraus resultierenden Gesundheitsrisiken befassen.

Using Geographically Referenced Data on Environmental Exposures for Public Health Research: A Feasibility Study Based on the German Socio-Economic Panel Study (SOEP)

Background: In panel datasets information on environmental exposures is scarce. Thus, our goal was to probe the use of area-wide geographically referenced data for air pollution from an external data source in the analysis of physical health. Methods: The study population comprised SOEP respondents in 2004 merged with exposures for NO2, PM10 and O3 based on a multi-year reanalysis of the EURopean Air pollution Dispersion-Inverse Model (EURAD-IM). Apart from bivariate analyses with subjective air pollution we estimated cross-sectional multilevel regression models for physical health as assessed by the SF-12. Results: The variation of average exposure to NO2, PM10 and O3 was small with the interquartile range being less than 10µg/m3 for all pollutants. There was no correlation between subjective air pollution and average exposure to PM10 and O3, while there was a very small positive correlation between the first and NO2. Inclusion of objective air pollution in regression models did not improve the model fit. Conclusions: It is feasible to merge environmental exposures to a nationally representative panel study like the SOEP. However, in our study the spatial resolution of the specific air pollutants has been too little, yet.