Real-time inference of thermotolerant coliforms in groundwater

Enteric pathogens are typically inferred from the presence of cultured surrogate indicator organisms such as thermotolerant coliforms (TTCs). Their analysis requires suitable laboratories, specialist trained personnel, and is time-consuming, which can limit sampling resolution, particularly during critical pollution events. Tryptophan-like fluorescence has been demonstrated as a useful indicator of human influence on freshwater resources due to its association with sewage and farm waste. Following recent developments in field-deployable optical sensor technology, portable tryptophan-like fluorimeters are now commercially available. We demonstrate their real-time applicability at potable urban groundwater supplies in the developing world. We sampled over 100 supplies for TTCs, and traditional surrogates, such as turbidity and nutrients, as well as tryptophan-like fluorescence. The intensity of tryptophan-like fluorescence was the most effective predictor of the presence/absence and number of TTCs. These sensors have the potential to be included in real-time pollution alert systems for drinking water supplies throughout the world, as well as mapping enteric pathogen risks in developing regions

Using emerging contaminants to trace rapid recharge pathways in urban groundwater: an example from Kabwe, Zambia

We explore the occurrence of emerging organic contaminants in groundwater beneath a medium-sized African town reputed to be one of the ten most contaminated places on Earth. The results represent the first investigation of many emerging contaminants anywhere within the African environment. Samples were obtained from shallow wells and deeper boreholes across peri-urban, lower and higher cost residential areas, and industrial land uses during both the dry and wet season. They were analyzed using a broad screen GC-MS method which can target over 1000 organic compounds. The insect repellent DEET was ubiquitous, with other compounds detected in less than 15% of the sources, including the bactericide triclosan, chlorination by-products and surfactants. Emerging contaminants were most prevalent in shallow wells in low cost residential areas, which were inadequately protected at the surface. Seasonal changes in DEET highlighted the aquifer is more vulnerable than previously considered and the utility of the compound as an urban wastewater tracer. There was a general absence of personal care products, life-style compounds, and pharmaceuticals which are commonly detected in the aquatic environment in the developed world. This perhaps reflects some degree of attenuation within the subsurface, but could also be a result of the current limited use of products containing emerging contaminants by locals due to unaffordability and unavailability

Urban groundwater quality in sub-Saharan Africa: current status and implications for water security and public health

Groundwater resources are important sources of drinking water in Africa, and they are hugely important in sustaining urban livelihoods and supporting a diverse range of commercial and agricultural activities. Groundwater has an important role in improving health in sub-Saharan Africa (SSA). An estimated 250 million people (40% of the total) live in urban centres across SSA. SSA has experienced a rapid expansion in urban populations since the 1950s, with increased population densities as well as expanding geographical coverage. Estimates suggest that the urban population in SSA will double between 2000 and 2030. The quality status of shallow urban groundwater resources is often very poor due to inadequate waste management and source protection, and poses a significant health risk to users, while deeper borehole sources often provide an important source of good quality drinking water. Given the growth in future demand from this finite resource, as well as potential changes in future climate in this region, a detailed understanding of both water quantity and quality is required to use this resource sustainably. This paper provides a comprehensive assessment of the water quality status, both microbial and chemical, of urban groundwater in SSA across a range of hydrogeological terrains and different groundwater point types. Lower storage basement terrains, which underlie a significant proportion of urban centres in SSA, are particularly vulnerable to contamination. The relationship between mean nitrate concentration and intrinsic aquifer pollution risk is assessed for urban centres across SSA. Current knowledge gaps are identified and future research needs highlighted

Urban groundwater quality in sub-Saharan Africa: current status and implications for water security and public health

Groundwater resources are important sources of drinking water in Africa, and they are hugely important in sustaining urban livelihoods and supporting a diverse range of commercial and agricultural activities. Groundwater has an important role in improving health in sub-Saharan Africa (SSA). An estimated 250 million people (40% of the total) live in urban centres across SSA. SSA has experienced a rapid expansion in urban populations since the 1950s, with increased population densities as well as expanding geographical coverage. Estimates suggest that the urban population in SSA will double between 2000 and 2030. The quality status of shallow urban groundwater resources is often very poor due to inadequate waste management and source protection, and poses a significant health risk to users, while deeper borehole sources often provide an important source of good quality drinking water. Given the growth in future demand from this finite resource, as well as potential changes in future climate in this region, a detailed understanding of both water quantity and quality is required to use this resource sustainably. This paper provides a comprehensive assessment of the water quality status, both microbial and chemical, of urban groundwater in SSA across a range of hydrogeological terrains and different groundwater point types. Lower storage basement terrains, which underlie a significant proportion of urban centres in SSA, are particularly vulnerable to contamination. The relationship between mean nitrate concentration and intrinsic aquifer pollution risk is assessed for urban centres across SSA. Current knowledge gaps are identified and future research needs highlighted

A review of urban groundwater use and water quality challenges in Sub-Saharan Africa

Large parts of Sub-Saharan Africa (SSA) are experiencing rapid urban population growth. Current projections estimate that by 2030 half the population of SSA will be living in urban areas, and if current trends persist half of these people will reside in slums. According to UN-Habitat, access to safe drinking water for slum dwellers is a major priority (UN-Habitat, 2003). Because of the lack of services, self-provision of water, using groundwater sources, is widespread in slums and is likely to increase as the urban centres expand, putting pressure on the quality and quantity of the groundwater resource. Over the last three decades there has been a concerted effort to increase access to improved water supply and sanitation across Africa. Within urban, and peri-urban, settings this has led to widespread development of groundwater resources for domestic water supply, mainly through growth in the private groundwater supply sector, and the proliferation of on-site sanitation, largely through the use of pit latrines. Due to the high population densities, latrines are often constructed in very close proximity to wells and springs used for drinking water, and can be a significant source of contamination. The lack of adequate management of household and industrial waste in many urban centres is also a growing concern. This has led to the groundwater resources being put under considerable stress in terms of water quality and in some cases water availability. The parallel deterioration of the water quality and availability in urban areas in SSA and increases in demand challenge the sustainability of the current situation. This has occurred over the last three decades for most urban centres in SSA (Foster et al., 1996). While there is not the very long historical legacy of urban pollution in many urban centres in SSA, in contrast with Europe and Asia for example, the problem of long term pollutant loading to groundwater is now becoming a reality. There is currently a limited evidence base of groundwater quality studies in urban centres across SSA with which to inform long term policy on the development of urban and peri-urban groundwater resources. This document provides an overview of urban and peri-urban drinking water and sanitation in SSA as well as urban groundwater development and degradation. The review draws on published and grey literature from across SSA and is both a useful entry point for researchers in this area and is a baseline reference work on the topic of urban groundwater quality in SSA. Detailed case studies from West Africa (Ibadan, Nigeria) and Southern Africa (Lusaka, Zambia) are included in this document. It provides: i) a detailed review of empirical studies assessing groundwater degradation (chemical and microbiological) in urban groundwater across SSA, ii) assesses urban groundwater quality issues in relation to groundwater vulnerability and hydrogeological controls, iii) identifies gaps in the current evidence base regarding groundwater quality and risks to groundwater pollution and human health in urban SSA

Tracing enteric pathogen contamination in sub-Saharan African groundwater

Quantitative PCR (qPCR) can rapidly screen for an array of faecally-derived bacteria, which can be employed as tracers to understand groundwater vulnerability to faecal contamination. A microbial DNA qPCR array was used to examine 45 bacterial targets, potentially relating to enteric pathogens, in 22 groundwater supplies beneath the city of Kabwe, Zambia in both the dry and subsequent wet season. Thermotolerant (faecal) coliforms, sanitary risks, and tryptophan-like fluorescence, an emerging real-time reagentless faecal indicator, were also concurrently investigated. There was evidence for the presence of enteric bacterial contamination, through the detection of species and group specific 16S rRNA gene fragments, in 72% of supplies where sufficient DNA was available for qPCR analysis. DNA from the opportunistic pathogen Citrobacter freundii was most prevalent (69% analysed samples), with Vibrio cholerae also perennially persistent in groundwater (41% analysed samples). DNA from other species such as Bifidobacterium longum and Arcobacter butzleri was more seasonally transient. Bacterial DNA markers were most common in shallow hand-dug wells in laterite/saprolite implicating rapid subsurface pathways and vulnerability to pollution at the surface. Boreholes into the underlying dolomites were also contaminated beneath the city highlighting that a laterite/saprolite overburden, as occurs across much of sub-Saharan aquifer, does not adequately protect underlying bedrock groundwater resources. Nevertheless, peri-urban boreholes all tested negative establishing there is limited subsurface lateral transport of enteric bacteria outside the city limits. Thermotolerant coliforms were present in 97% of sites contaminated with enteric bacterial DNA markers. Furthermore, tryptophan-like fluorescence was also demonstrated as an effective indicator and was in excess of 1.4 μg/L in all contaminated sites

Failing the academy: low written output in an African University

Publishing trends of academic staff at University of Zambia and doctors at University Teaching HospitalThe study investigated the publishing trends of academic staff at University of Zambia and doctors at University Teaching Hospital in order to highlight the trends and possible barriers to publishing by academic staff and doctors. The studied reviewed publication histories of academic staff at the university for the period 2000 to 2005 by examining university documents in three schools (engineering, medicine, and mines), by author searches on PubMed search engine, surveys by questionnaire, and focus group discussions with workshop participants. Twenty nine questionnaires, 58% response rate, were returned and 35 academic staff (70%) of the workshop attendants participated in the focus group discussions. The questionnaire respondents' profile was 1 full professor, 5 senior lecturers, 19 lecturers, 4 honorary lecturers. All participants had a minimum of a Masters degree. The publication trends were low at all academic ranks ranging from professors, associate professors, senior lecturers, and lecturers. Over 75% of respondents had between 0-3 publications, 10% had between 4-8 publications and another 10% had between 9-15 publications, while less than 3% reported having more than 15 publications.Office of Global AIDS/US Department of State

Emerging contaminants in urban groundwater sources in Africa

The occurrence of emerging organic contaminants within the aquatic environment in Africa is currently unknown. This study provides early insights by characterising a broad range of emerging organic contaminants (n > 1000) in groundwater sources in Kabwe, Zambia. Groundwater samples were obtained during both the dry and wet seasons from a selection of deep boreholes and shallow wells completed within the bedrock and overlying superficial aquifers, respectively. Groundwater sources were distributed across the city to encompass peri-urban, lower cost housing, higher cost housing, and industrial land uses. The insect repellent DEET was ubiquitous within groundwater at concentrations up to 1.8 mg/L. Other compounds (n ¼ 26) were detected in less than 15% of the sources and included the bactericide triclosan (up to 0.03 mg/L), chlorination by-products e trihalomethanes (up to 50 mg/L), and the surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol (up to 0.6 mg/L). Emerging contaminants were most prevalent in shallow wells sited in low cost housing areas. This is attributed to localised vulnerability associated with inadequate well protection, sanitation, and household waste disposal. The five-fold increase in median DEET concentration following the onset of the seasonal rains highlights that more mobile compounds can rapidly migrate from the surface to the aquifer suggesting the aquifer is more vulnerable than previously considered. Furthermore it suggests DEET is potentially useful as a wastewater tracer in Africa. There was a general absence of personal care products, life-style compounds, and pharmaceuticals which are commonly detected in the aquatic environment in the developed world. This perhaps reflects some degree of attenuation within the subsurface, but could also be a result of the current limited use of products containing emerging contaminants by locals due to unaffordability and unavailability. As development and population increases in Africa, it is likely a wider-range of emerging contaminants will be released into the environment

Tracking pathways for pathogen contamination in urban groundwater supplies in Africa: novel application of qPCR techniques

Low income urban communities across Africa depend on local shallow, often highly contaminated, groundwater sources for drinking and domestic use as well as larger municipal supplies extracting groundwater from deeper within the aquifer system where these are available and affordable. Rapid lateral and vertical pathways in the subsurface, often only active for limited periods e.g. during high water table conditions, can lead to rapid deterioration of groundwater quality. Sanitary risk assessments and quantification of basic water quality indicators such thermotolerant coliforms are often used as part of water point vulnerability assessments in urban and peri-urban water supplies in Africa. While there have been huge advances in the development of polymerase chain reaction (PCR) techniques in recent years for amplifying microbial DNA, these techniques have not been used to date for quantifying specific pathogenic strains of bacteria in groundwaters in Africa. In this paper we present results from a pilot study using qPCR techniques for the first time to quantify the occurrence of 26 specific pathogenic strains in water supplies in Kabwe, Zambia. Pathogen occurrence is assessed in both shallow and deep groundwater points during both the wet and dry season in a vulnerable dolomite aquifer system. Multiple pathogens were revealed within the groundwater system including Vibrio cholera and Salmonella enterica. This technique shows great potential for tracking specific pathogens, fingerprinting sources of pathogens in groundwater sources and assessing rapid shallow pathways in widespread vulnerable settings in Africa, and elsewhere, such as those found in lateritic or karstic terrains

In-situ tryptophan-like fluorescence: a real-time indicator of faecal contamination in drinking water supplies

Enteric pathogens are typically inferred from the presence of surrogate indicator organisms such as thermo-tolerant (faecal) coliforms (TTCs). The analysis of TTCs requires time-consuming incubation in suitable laboratories, which can limit sampling resolution, particularly during critical pollution events. Here, we demonstrate the use of in-situ fluorimeters targeting tryptophan-like compounds as a rapid, reagentless indicator of TTCs in groundwater-derived potable water supplies in Africa. A range of other common indicators of TTCs were also determined including nitrate, turbidity, and sanitary risk survey scores. Sampling was conducted during both the dry and wet seasons to investigate seasonality. Tryptophan-like fluorescence was the most effective predictor of both presence/absence and number of TTCs during both seasons. Seasonal changes in tryptophan-like fluorescence in deeper supplies suggest it is transported more efficiently through the aquifer than TTCs. Moreover, the perennial elevated concentrations in some wells suggest it is more resilient than TTCs in groundwater. Therefore tryptophan-like fluorescence could also be a better indicator of some smaller, more easily transported, and long-lived, pathogenic enteric viruses. These sensors have the potential to be included in real-time pollutionalert systems for drinking water supplies throughout the world, as well as for mapping enteric pathogen risks in developing regions