This paper explores the nature, source and spatial variation of the salinity of water used for irrigation in a coastal urban farming area in Cape Town, South Africa, where water from the Cape Flats aquifer is drawn into storage ponds and used for crop irrigation. Water samples were collected in summer and winter from selected sites across the study area and were analysed for salinity as well as for concentrations of major and minor ions. Each site consists of one borehole and one pond. Isotope analysis was done for the summer samples so as to assess effects of evaporation on water quality and salinity. Descriptive statistics were used to compare the variation in range of concentration of specific ions with the recommended ranges set by the South African Department of Water Affairs and Forestry (DWAF) and the Food and Agriculture Organisation (FAO). Geographical information system (GIS) analysis was used to describe the spatial distribution of salinity across the study area, and hydro-geochemical analysis was used to assess the possibility of seawater intrusion into the aquifer system and to characterise groundwater in the study area. The results of the research showed that the concentrations of chloride, nitrate, potassium and sodium exceeded the target maximum limit according to DWAF and FAO guidelines. Groundwater and pond water were also observed to be brackish in most parts of the research area in terms of total dissolved salts content, and fresh water was only found in the middle section of the research area. It is concluded that the accumulation of salts in groundwater and soil in the study area is mainly due to the agricultural activities and partially due to the natural movement of water through the geological formation of the Cape Flats region. These findings permit the formulation of a conceptual model of the occurrence of the salinization process, which implies that the groundwater and pond water in the study area are generally suitable for irrigation purposes, but need to be used with caution as the vegetables grown are classified as sensitive and moderately sensitive to salt according to DWAF guidelines for irrigation water quality (1996). The research paves a way for possible quantitative simulation of salt mass balance in future.

In rural Africa, scientific evidence is often lacking to guide the scaling-up of groundwater as the safest source of potable water. An investigation was conducted in the Upper Limphasa Catchment in northern Malawi to determine the safety of groundwater sources and to explore factors influencing water quality. Water samples from 17 boreholes, 6 hand-dug wells and 90 households were analysed for selected parameters. Portable incubators, multi-parameter probe and colorimetric standard methods were used for field measurements, and standard methods were used for laboratory water analysis. Results were compared to specified guidelines of the World Health Organization and Malawi Bureau of Standards to establish the potability of water. Statistical results using non-parametric t-tests indicated that the wells were more contaminated with E. colibacteria than boreholes (p=6.2x10-6), suggesting non-consideration of local hydrogeologic factors in groundwater development. Water from boreholes that tested negative for pathogens at source tested positive at some households (total coliform:p=0.0042 and E. colip=7.8x10(7)) suggesting the effect of handling practices. Water from wells that was not treated with chlorine showed higher levels of E. coli than treated water from the same sources, confirming the effectiveness of chlorine in reducing pathogenic bacteria in households' stored drinking-water, reinforcing the scientific basis for scaling up chlorine as effective disinfectant. However, this study demonstrated that chlorine failed to effectively eliminate all pathogens in drinking water. As a case study in tropical rural environments in Africa, these findings on the suitability of using chlorine as disinfectant and on factors explaining groundwater contamination, though provisional, provide a scientific basis for assessing cost-effectiveness and sustainability of scaling-up the use of chlorine as a curative remedy and of systematically investigating local hydrogeologic factors in order to implement measures to protect groundwater quality in poverty-prone rural communities.

Com o aumento da asma observado em nível mundial nas últimas três décadas, também ficou claro que se trata de uma doença social, conforme evidenciado por indicadores demográficos e socioeconômicos agrupados por áreas residenciais. Esta tendência não pode ser explicada apenas por paradigmas genéticos tradicionais ou influência física do ambiente, quando considerados isoladamente. Por isso passou-se a considerar a interação entre riscos ambientais físicos e psicológicos e os determinantes de risco moleculares e genéticos (i.e. enquadramento biomédico) no âmbito de um contexto socioambiental mais amplo, incluindo a posição socioeconômica como "causa das causas" (i.e. enquadramento ecológico). Estratégias de pesquisa transdisciplinares ou programas que acolhem esta complexidade por meio de uma estrutura conceitual comum integrando teorias, modelos, medidas e métodos analíticos específicos das diversas disciplinas à pesquisa atual da asma podem representar contribuições particularmente significantes a uma melhor compreensão de uma doença social. Este artigo em forma de relato de caso pretende dar uma visão geral de um estudo longitudinal usando vários níveis e métodos - o Asthma Coalition on Community, Environment and Social Stress (ACCESS) -, para mostrar as oportunidades e desafios de um estudo transdisciplinar investigando a expressão urbana da asma nos Estados Unidos.

As we have seen a global increase in asthma in the past three decades it has also become clear that it is a socially patterned disease, based on demographic and socioeconomic indicators clustered by areas of residence. This trend is not readily explained by traditional genetic paradigms or physical environmental exposures when considered alone. This has led to consideration of the interplay among physical and psychosocial environmental hazards and the molecular and genetic determinants of risk (i.e., biomedical framing) within the broader socioenvironmental context including socioeconomic position as an upstream "cause of the causes" (i.e., ecological framing). Transdisciplinary research strategies or programs that embrace this complexity through a shared conceptual framework that integrates diverse discipline-specific theories, models, measures, and analytical methods into ongoing asthma research may contribute most significantly toward furthering our understanding of socially patterned disease. This paper provides an overview of a multilevel, multimethod longitudinal study, the Asthma Coalition on Community, Environment and Social Stress (ACCESS), as a case study to exemplify both the opportunities and challenges of transdisciplinary research on urban asthma expression in the United States.

Com o aumento da asma observado em nível mundial nas últimas três décadas, também ficou claro que se trata de uma doença social, conforme evidenciado por indicadores demográficos e socioeconômicos agrupados por áreas residenciais. Esta tendência não pode ser explicada apenas por paradigmas genéticos tradicionais ou influência física do ambiente, quando considerados isoladamente. Por isso passou-se a considerar a interação entre riscos ambientais físicos e psicológicos e os determinantes de risco moleculares e genéticos (i.e. enquadramento biomédico) no âmbito de um contexto socioambiental mais amplo, incluindo a posição socioeconômica como "causa das causas" (i.e. enquadramento ecológico). Estratégias de pesquisa transdisciplinares ou programas que acolhem esta complexidade por meio de uma estrutura conceitual comum integrando teorias, modelos, medidas e métodos analíticos específicos das diversas disciplinas à pesquisa atual da asma podem representar contribuições particularmente significantes a uma melhor compreensão de uma doença social. Este artigo em forma de relato de caso pretende dar uma visão geral de um estudo longitudinal usando vários níveis e métodos - o Asthma Coalition on Community, Environment and Social Stress (ACCESS) -, para mostrar as oportunidades e desafios de um estudo transdisciplinar investigando a expressão urbana da asma nos Estados Unidos.

As we have seen a global increase in asthma in the past three decades it has also become clear that it is a socially patterned disease, based on demographic and socioeconomic indicators clustered by areas of residence. This trend is not readily explained by traditional genetic paradigms or physical environmental exposures when considered alone. This has led to consideration of the interplay among physical and psychosocial environmental hazards and the molecular and genetic determinants of risk (i.e., biomedical framing) within the broader socioenvironmental context including socioeconomic position as an upstream "cause of the causes" (i.e., ecological framing). Transdisciplinary research strategies or programs that embrace this complexity through a shared conceptual framework that integrates diverse discipline-specific theories, models, measures, and analytical methods into ongoing asthma research may contribute most significantly toward furthering our understanding of socially patterned disease. This paper provides an overview of a multilevel, multimethod longitudinal study, the Asthma Coalition on Community, Environment and Social Stress (ACCESS), as a case study to exemplify both the opportunities and challenges of transdisciplinary research on urban asthma expression in the United States.