The paper by Gorelick et al. [1983] on the identification of groundwater pollution sources most certainly addresses a significant contemporary hydrologic problem. The approach that they describe could find application in detection of inputs to surface water systems as well as in detection of sources of groundwater pollution. Indeed, approaches similar to their steady state conservative model have been used recently in slightly different contexts.Woolhiser et al. [1979, 1982] developed a technique to estimate multiple inflows to a stream reach based on a quadratic programming solution to find the unknown inflow quantities that minimized the sum of squares of normalized errors for up to eight ion balance equations, subject to a water balance constraint and a nonnegativity constraint. They used Monte Carlo techniques to investigate the sensitivity of the solution to errors in the chemical analyses and stream flow measurements. Chemical element balances (CEB's) have also been used to identify sources of particulates for many elements which can be associated with specific types of air pollution sources [Kowalczyk et al., 1982]. According to the CEB model, the composition of particles at a receptor is a linear combination of concentration patterns of particles from contributing sources. Kowalczyk et al. [1982] determined source strength coefficients by a least squares fit to the observed concentrations of several "marker elements." Tsurumi [1982] utilized the multiple ion balance approach to estimate not only the relative proportions of sources present in a mixture but also the ranges of chemical composition of the sources of chemical constituents. His method requires several mixtures of the source waters at different proportions and uses an iterative least squares solution. The source compositions are also subject to an anion-cation balance constraint.The objective of all of these techniques is to select a subset of sources, from the set of physically feasible sources, which results in simulated concentrations representing the best match with a sample. "Best" is, of course, defined in terms of the objective function and imposed constraints. The works cited above can be viewed as extensions of earlier works in which it was assumed that stream water or groundwater is a mixture of solutions derived from different steady state origins, with no loss of dissolved species occurring before or after mixing [Piper, 1944;Pinder and Jones, 1969;Visocky, 1970;Hall, 1970; Sklash et al., 1976]. Previous works, however, have considered only models of complete mixing in a lumped system and have considered only conservative substances. Thus, the approach of Gorelick et al. This paper is not subject to U.S. copyright. Published in 1984 by the American Geophysical Union. Paper number 4W0423.[1983] is novel because it introduces a method to treat a distributed system by incorporating a groundwater solute transport model and a nonconservative tracer. The transient case had also not been considered previously.Although Gorelick et al. [198...

BackgroundThe Sustainable Development Goals include commitments to end poverty, and promote education for all, gender equality, the availability of water and decent work for all. An important constraint is the fact that each day, many millions of women and children, and much less frequently men, carry their household’s water home from off-plot sources. The burden of fetching water exacerbates gender inequality by keeping women out of education and paid employment. Despite speculation about the potential health impacts of fetching water, there is very little empirical evidence. We report the first large study of the health impacts of carrying water on women and children.MethodsA cross-sectional survey was conducted in South Africa, Ghana and Vietnam during 2012. It investigated water carrying methods and health status. Because areas of self-reported pain were correlated we undertook factor analysis of sites of reported pain, to interpret patterns of pain reporting. Regression analysis using Generalised Estimating Equations (GEE) investigated water carrying as a risk factor for general health and self-reported pain.ResultsPeople who previously carried water had increased relative risk of reporting pain in the hands (risk ratio RR 3.62, 95% confidence interval CI 1.34 to 9.75) and upper back (RR 2.27, 95% CI 1.17 to 4.40), as did people who currently carry water (RR hand pain 3.11, 95% CI 1.34 to 7.23; RR upper back pain 2.16, 95% CI 1.25 to 3.73). The factor analysis results indicate that factor 1, ‘axial compression’, which is correlated with pain in the head and upper back, chest/ribs, hands, feet and abdomen/stomach, is associated with currently (0.30, 95% CI 0.17 to 0.43) or previously (0.21, 95% CI 0.01 to 0.42) carrying water. Factor 2, ‘soft tissue strain’, which is correlated with pain in the neck, shoulders/arms, lower back and hips/pelvis or legs, is marginally negatively associated with currently (-0.18, 95% CI -0.32 to -0.04) carrying water. The factor ‘axial compression’ was more strongly associated with carrying water containers on the head.ConclusionsParticipants who reported a history of current or past water carrying more frequently reported pain in locations most likely to be associated with sustained spinal axial compression in the cervical region. Given the fact that cervical spinal conditions are globally one of the more common causes of disability, our findings suggest that water carrying, especially by head loading is a major contributing factor in musculoskeletal disease burden in low income countries. Our findings support the proposed indicator for monitoring SDG6.1: “Percentage of population using safely managed drinking water services at home.”

10Irrigation with raw, partially and treated wastewater is a widespread practice in many 11 arid and semi-arid zones. The importance of wastewater for agriculture has 12 increasingly been recognised not only as a valuable water resource but also for its 13 nutrient value. However, inappropriate management of irrigation with wastewater can 14 pose substantial risks to public health and the surrounding environment as a result of 15 its microbial and toxic components. In this review, we summarise recent research 16 and provide a broad overview of the potential risks associated with the chemicals in 17 wastewater used for irrigation including their environmental, and health impacts, 18 factors that may affect the fate of these chemicals, and available mitigation methods 19 and management options to reduce their impacts. A primary aim of this review is to 20 construct a generalised ranking of the risks from the chemical constituents of 21 wastewater used for irrigation in arid and semi -arid zones. 22 . 23 Keywords: irrigation with wastewater, environmental24 risks, chemical constituents, wastewater 25 management, arid zones 26 to human health and environmental quality as a result of the microbial and toxic 56components is a serious obstacle for wastewater reuse in agriculture. Most of the 57 existing research has tended to focus on the microbial risks regarding the use of 58 wastewater and guidelines for the safe use of wastewater in agriculture. This may be 59 due to the immediate effects of microbiological components on public health 60 compared to the longer term risks posed by chemical exposure ((WHO, 2006, Bos et 61 al., 2010. Generally, using wastewater in agriculture is unlikely to contribute to direct 62 health impacts from chemicals hazards unless the wastewater is heavily 63 contaminated with discharges from industrial sources. Another explanation may be 64 the difficulty in assessing the health impacts of toxic chemicals in wastewater as it 65 usually has a long latency period (Bos et al., 2010). 66Inappropriate management of wastewater irrigation can contribute to serious 67 environmental problems especially in arid and semi-arid zones where wastewater 68 could be the predominant water supply for agriculture (Pescod, 1992, Ayers and 69 Westcot, 1985, WHO, 2006, Simmons et al., 2010. Wastewater irrigation could lead 70 to negative impacts on soil properties and fertility, crop yields, groundwater and 71 surface water quality, and the aquatic ecosystem. The magnitude of the potential 72 impacts will depend on the concentration of the chemicals, their solubility and 73 inherent toxicity. Other important factors the rate and frequency of wastewater 74 application, the type of crop, and target yields, inhertent soil properties and condition, 75 the vulnerability of the aquifer, climatic conditions, and technology level and the 76 social-economic status of the farmers. In order to ensure good crop yields and 77 minimise the environmental risks associated with the chemical constituents in 78wastewater, a r...

This paper outlines the findings of a fecal sludge management (FSM) initial scoping study in twelve cities. This short, desk-based study used innovative tools to assess the institutional context and the outcome in terms of the amount of fecal sludge safely managed. A range of cities was included in the review, all in low-and middle-income countries.None of the cities studied managed fecal sludge effectively, although performance varied. Where cities are seeking to address fecal sludge challenges the solutions are, at best, only partial, with a focus on sewerage which serves a small minority in most cases. FSM requires strong city-level oversight and an enabling environment that drives coordinated actions along the sanitation service chain; this was largely absent in the cities studied.Based on the findings of the review a typology of cities was developed to aid the identification of key interventions to improve FSM service delivery. Additional work is recommended to further improve the tools used in this study in order to enable better understanding of the FSM challenges and identify appropriate operational solutions.