A fibre optic evanescent wave sensor used for the detection of trace nitrites in water

A fibre optic technique for detecting trace amounts of nitrite compounds in water is described. The off-line fibre optic sensor outlined here is based on evanescent field absorption in a test solution formed by the reaction of nitrite compounds in water with suitable chemical reagents. A short unclad portion of a plastic clad silica fibre acts as the sensing region. The experimental results clearly establish the usefulness of the present technique for detecting very low concentrations of the order of 1 ppb (parts per billion) of nitrite compounds with a large dynamic range of 1–1000 ppb. Such a high sensitivity enables the present device to be used for measuring the nitrite content in drinking water.

Speciation and variation in the occurrence of haloacetic acids in three water supply systems in England

An investigation into the speciation and occurrence of nine haloacetic acids (HAAs) was conducted during the period of April 2007 to March 2008 and involved three drinking water supply systems in England, which were chosen to represent a range of source water conditions; these were an upland surface water, a lowland surface water and a groundwater. Samples were collected seasonally from the water treatment plants and at different locations in the distribution systems. The highest HAA concentrations occurred in the upland surface water system, with an average total HAA concentration of 21.3 μg/L. The lowest HAA levels were observed in the groundwater source, with a mean concentration of 0.6 μg/L. Seasonal variations were significant in the HAA concentrations; the highest total HAA concentrations were found during the autumn, when the concentrations were approximately two times higher than in winter and spring. HAA speciation varied among the water sources, with dichloroacetic acid and trichloroacetic acid dominant in the lowland surface water system and brominated species dominant in the upland surface water system. There was a strong correlation between trihalomethanes and HAAs when considering all samples from the three systems in the same data set (r2=0.88); however, the correlation was poor/moderate when considering each system independently.

Managing Water Quality in Agricultural Catchments

Until recently, pollution control in rural drainage basins of the UK consisted solely of water treatment at the point of abstraction. However, prevention of agricultural pollution at source is now a realistic option given the possibility of financing the necessary changes in land use through modification of the Common Agricultural Policy. This paper uses a nutrient export coefficient model to examine the cost of land-use change in relation to improvement of water quality. Catchment-wide schemes and local protection measures are considered. Modelling results underline the need for integrated management of entire drainage basins. A wide range of benefits may accrue from land-use change, including enhanced habitats for wildlife as well as better drinking water.

Risk assessment of trihalomethanes from tap water in Fortaleza, Brazil

The cancer risks (CR) by oral ingestion, dermal absorption, and inhalation exposure of trihalomethanes (THM) from tap water of ten districts in Fortaleza, Brazil were estimated. The mean levels of THM compounds were obtained in Fortaleza tap water as follow: 63.9 mu g L(-1) for chloroform (CHCl(3)), 40.0 mu g L(-1) for bromodichloromethane (CHBrCl(2)), and 15.6 mu g L(-1) for dibromochloromethane (CHBr(2)Cl). Bromoform (CHBr(3)) was not detected. The mean CR for THMs in tap water is 3.96 x 10(-4). The results indicate that Fortaleza residents have a higher CR by inhalation than dermal absorption and oral ingestion. The CR for CHCl(3) contributes with 68% as compared with the total CR, followed by CHBrCl(2) (21%), and CHBr(2)Cl (11%). The hazard index (HI) is about ten times lower than unity, not indicating non-cancer effects.

Community water fluoridation : is it still worthwhile

Community Water Fluoridation (CWF) is the adjustment of fluoride concentration in community drinking water to a level that confers optimal protection from dental caries (Truman et al 2002). It is supported by many authorities as the single most effective public health measure for reducing dental caries (DHS 2007). It has consistently been shown to be effective in reducing the prevalence and severity of dental caries in populations following its introduction (NHMRC 1999). The most dramatic reductions (50-60%) were demonstrated in the earlier studies although more recent research has still shown reductions of between 30 and 50% (Truman et al 2002). Despite the strong scientific evidence for its beneficial effects and safety the issue of the appropriateness of CWF is often the focus of public debate. Proponents argue that it reduces dental caries. is safe and cost effective. and that it provides significant benefits to all social classes (Slade et al 1995: Slade et a 1996: Spencer et al 1996). Opponents question its efficacy and safety and argue that its addition to community water supplies is unethical mass medication (Colquhoun 1990: Diesendorf 1986: Diesendorf et al 1997).

More recently, however, there have been important questions raised regarding the continuing benefit of CWF over and above that produced by the widespread use of other sources of fluoride (toothpaste. mouth rinses. varnish and other professionally applied fluorides). Generally, dental caries has declined steeply in the last thirty years and many have observed that dental caries has also reduced in parts of Australia and other countries where there has never been CWF or where it has ceased. It has been suggested that because of the current low population levels of dental caries and the increase in alternate sources of fluoride, CWF no longer offers the benefits it may have in the past. Given this notion, together with the concerns of a minority subgroup of the population regarding the safety of CWF, it is valuable to examine current evidence to answer the question: Is there still a role for CWF in Australia?

This paper will firstly examine the history of water fluoridation and its mechanisms of action. Secondly. trends in dental decay experience over the last three decades with particular emphasis on social and geographical inequities in Australia will be described. We also review the current state of scientific evidence for the benefits of CWF including the contribution it makes to the reduction of oral health inequalities. In light of this we will provide a response to the question posed above.

The ill effects of public sector corruption in the water and sanitation sector

In general, given a particular set of institutions, the greater a county's per capita income, the more extensive will be its pro vision of goods and services that require concerted public action. We contend that one of the most important aspects of institutions in this regard is public sector corruption. We test this contention by analyzing 85 countries observed in 1990, 1995, 2000, and 2004--the only years for which data on improved drinking water and adequate sanitation are available. The models point to statistically significant, negative relations between corruption and access to both improved drinking water and adequate sanitation.

Innovative reuse options for water treatment plant sludges

Reuse options were investigated for drinking water sludge. Research found sludges could be included with raw materials in brick and cement manufacturing with minimal impact. Poly-aluminium chloride sludge was found to an excellent adsorbent of phosphorus from wastewaters thus indirectly reducing potential algal blooms in our rivers.

Molecular physiology of water balance in the Spinifex hopping mouse

Many animals live in the deserts of Australia and survive without drinking water. This research examined desert adaptations in the Spinifex hopping mouse (Notomys alexis), and is the first study to demonstrate how many genes and exzymes in the kidney are controlled to maintain water balance in the absence of drinking water.

Water deprivation induces appetite and alters metabolic strategy in Notomys alexis : unique mechanisms for water production in the desert

Like many desert animals, the spinifex hopping mouse, Notomys alexis, can maintain water balance without drinking water. The role of the kidney in producing a small volume of highly concentrated urine has been well-documented, but little is known about the physiological mechanisms underpinning the metabolic production of water to offset obligatory water loss. In Notomys, we found that water deprivation (WD) induced a sustained high food intake that exceeded the pre-deprivation level, which was driven by parallel changes in plasma leptin and ghrelin and the expression of orexigenic and anorectic neuropeptide genes in the hypothalamus; these changed in a direction that would stimulate appetite. As the period of WD was prolonged, body fat disappeared but body mass increased gradually, which was attributed to hepatic glycogen storage. Switching metabolic strategy from lipids to carbohydrates would enhance metabolic water production per oxygen molecule, thus providing a mechanism to minimize respiratory water loss. The changes observed in appetite control and metabolic strategy in Notomys were absent or less prominent in laboratory mice. This study reveals novel mechanisms for appetite regulation and energy metabolism that could be essential for desert rodents to survive in xeric environments.

Urban growth in arid environments : developing water sustainability indicators for Abu Dhabi (UAE)

The United Arab Emirates (UAE) face a serious water problem. It has a very dry climate, high evaporation rate, combined with large water consumption from fast growing population, economic activities and uncontrolled uses of water for irrigation. Currently, UAE has one of the largest water footprints in the world. Groundwater is overexploited. Waste water is increasingly being treated to supply non-drinking water, but it still cover a small proportion of the demand. Desalination of sea water is the main source of potable water in UAE, but the high economic cost of desalination, its intensive energy demand and the adverse effects of its effluents on the marine life are a major concern. Other factors contributing to the problem are the focus of water management policies on keep supplying the growing demand for water, the increase of the per capita water consumption, and the free water charge for most of population. This research goal is to develop a water sustainability set of indicators for the challenging context of UAE. This paper presents the first stage of the research. Based on a review of the literature, the proposed framework involves 19 indicators, divided into four categories: water availability; water quality; water use efficiency; and policy and governance. Using an integrated cause-effect approach (DSR - Driving force, State, Response), the indicators were related in terms of their interdependencies, with a holistic view of the city water cycle. A preliminary test of the indicators to Abu Dhabi as a case study allowed an evaluation of the main 'Driving force' on the system, such as the scarcity of water due to natural constraints of the region, and increasing water consumption patterns of modern society; an assessment of the current 'state', which is under serious water stress. Also it indicated some potential 'responses', such as implementing policies for increasing efficient use.

Plastic water the social and material life of bottled water

How did branded bottles of water insinuate themselves into our daily lives? Why did water become an economic good—no longer a common resource but a commercial product, in industry parlance a “fast moving consumer good,” or FMCG? Plastic Water examines the processes behind this transformation. It goes beyond the usual political and environmental critiques of bottled water to investigate its multiplicity, examining a bottle of water’s simultaneous existence as, among other things, a product, personal health resource, object of boycotts, and part of accumulating waste matter. Throughout, the book focuses on the ontological dimensions of drinking bottled water—the ways in which this habit enacts new relations and meanings that may interfere with other drinking water practices.

A Gradient-Type Method For Real-Time State Estimation Of Water Distribution Networks

Drinking water distribution networks risk exposure to malicious or accidental contamination. Several levels of responses are conceivable. One of them consists to install a sensor network to monitor the system on real time. Once a contamination has been detected, this is also important to take appropriate counter-measures. In the SMaRT-OnlineWDN project, this relies on modeling to predict both hydraulics and water quality. An online model use makes identification of the contaminant source and simulation of the contaminated area possible. The objective of this paper is to present SMaRT-OnlineWDN experience and research results for hydraulic state estimation with sampling frequency of few minutes. A least squares problem with bound constraints is formulated to adjust demand class coefficient to best fit the observed values at a given time. The criterion is a Huber function to limit the influence of outliers. A Tikhonov regularization is introduced for consideration of prior information on the parameter vector. Then the Levenberg-Marquardt algorithm is applied that use derivative information for limiting the number of iterations. Confidence intervals for the state prediction are also given. The results are presented and discussed on real networks in France and Germany.

Bottled mineral water as a potential source of antibiotic resistant bacteria

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ultrasound efficiency in relation to sodium hypochlorite and filtration adsorption in microbial elimination in a water treatment plant

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The natural radioactivity in water by gross alpha and beta measurements

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)