Search results for "water supply"

Determination of antimony in drinking waters by an inexpensive, reproducible hydride generator for atomic spectroscopy.

1991

A method for determining antimony in drinking waters is described. In order to prevent a substantial error caused by the different oxidation states of antimony, Sb(V) is reduced to Sb(III) with potassium iodide-ascorbic acid. Covalent hydride is generated with a home made device by adding NaBH4. The hydride is then atomized in a flame-heated silica tube and atomic absorption is measured spectrophotometrically. The optimal conditions for this determination are discussed and interference effects are described. Results obtained by determining linearity range (0-200 ng), detection (LOD) and quantitation (LOQ) limits (LOD = 0.347 ng/ml, LOQ = 1.158 ng/ml), precision (instrumental CV 4.08% and me…

Experimental and modeling analysis of an apparent losses reduction device

2009

Carbonates from the ancient world's longest aqueduct:A testament of Byzantine water management

2021

The fourth‐ and fifth‐century aqueduct system of Constantinople is, at 426 km, the longest water supply line of the ancient world. Carbonate deposits in the aqueduct system provide an archive of both archaeological developments and palaeo‐environmental conditions during the depositional period. The 246‐km‐long aqueduct line from the fourth century used springs from a small aquifer, whereas a 180‐km‐long fifth‐century extension to the west tapped a larger aquifer. Although historical records testify at least 700 years of aqueduct activity, carbonate deposits in the aqueduct system display less than 27 years of operation. This implies that the entire system must have been cleaned of carbonate…

Speciation and oxidation kinetics of arsenic in the thermal springs of Wiesbaden spa, Germany.

2001

Since 1886 arsenic has been known to be present as a trace component in the Wiesbaden thermal waters at concentrations of over 100 microg L(-1). In this study for the first time molecular level speciation of arsenic was measured both in the water (by HG-AAS) and in wellstone scale deposits (by XANES). Most of the arsenic in the anoxic NaCl-type waters is in the reduced arsenite form. Hydrous ferric oxide (HFO) precipitates in the scale deposits scavenge only the minor dissolved arsenate portion which is, however, accumulated up to 3% w/w. Isothermal precipitation experiments at in-situ temperatures showed a difference between the progress of both arsenic and iron oxidation and precipitation…

Historical and Technical Notes on Aqueducts from Prehistoric to Medieval Times

2013

The aim of this paper is to present the evolution of aqueduct technologies through the millennia, from prehistoric to medieval times. These hydraulic works were used by several civilizations to collect water from springs and to transport it to settlements, sanctuaries and other targets. Several civilizations, in China and the Americas, developed water transport systems independently, and brought these to high levels of sophistication. For the Mediterranean civilizations, one of the salient characteristics of cultural development, since the Minoan Era (ca. 3200-1100 BC), is the architectural and hydraulic function of aqueducts used for the water supply in palaces and other settlements. The M…

Implementation of pressure reduction valves in a dynamic water distribution numerical model to control the inequality in water supply

2013

The analysis of water distribution networks has to take into account the variability of users' water demand and the variability of network boundary conditions. In complex systems, e.g. those characterized by the presence of local private tanks and intermittent distribution, this variability suggests the use of dynamic models that are able to evaluate the rapid variability of pressures and flows in the network. The dynamic behavior of the network also affects the performance of valves that are used for controlling the network. Pressure reduction valves (PRVs) are used for controlling pressure and reducing leakages. Highly variable demands can produce significant fluctuation of the PRV set po…

Drinking water source and cigarette smoking in transitional cell carcinoma of the bladder.

2006

OBJECTIVE: Water source and cigarette smoking are related to clinical characteristics and pathology of superficial transitional cell carcinoma of the bladder. METHODS: Tumor number, dimension, G-grade, T-stage, recurrences, cigarette smoking and water supply were recorded in patients harboring Ta-T1 G1-3 transitional cell carcinoma of the bladder. RESULTS: Of 577 patients, 61% had multiple and 36% recurrent tumors. Two hundred and forty-one patients (42%) were current smokers and 188 (33%) were former smokers. Bottled water was the only drinkable source for 249 (45%) patients, municipal water supply for 177 (32%), artesian wells for 38 (7%), spring water for 7 (1%) and mixed source for 89 (…

Environment, wealth, inequality and the burden of disease in the Accra metropolitan area, Ghana

2005

The study examines environmental problems and adverse impacts on the health of urban households in the Accra metropolitan area, Ghana. Accra is faced with severe inadequacy of urban infrastructure in the face of rapid population growth in the metropolis. More than half of the city's population do not have access to solid waste collection services. Only 39.8% of households have indoor pipe and over 35.0% of households depend on unsanitary public latrines whilst 2.5% do not have access to toilet facilities. Human excrement, garbage and wastewater are usually deposited in surface drains, open spaces and streams in poor neighbourhoods. The resultant poor sanitation has serious health impacts as…

Assessing Hydrus-2D model to investigate the effects of different on-farm irrigation strategies on potato crop under subsurface drip irrigation

2019

The objective of this paper was to assess the performance of Hydrus-2D model to simulate the effects of different on-farm irrigation strategies applied on potato crop. The ability of the model to simulate the stress coefficient (Ks), obtained as the ratio between actual and maximum transpiration, and to define the productive function of potato crop under the semi-arid conditions of central Tunisia were also evaluated. Experiments were carried out on potato crop under full (FI) and deficit irrigation (DI) and two different water qualities supplied by means of a subsurface drip irrigation system. Results evidenced that the model, despite some discrepancies locally observed, can fairly accurat…

Response of vine leaf water potential to quick variation in canopy exposure. Example of canopy opening manipulation of Merlot (<em>Vitis vinife…

2004

<p style="text-align: justify;">Plants are in general subject to rapid fluctuations in the environment, particularly as regards the interception of light and therefore water regime. It is important to know the duration and the amplitude of response of the water regime (first leaf water potential) when light interception changes suddenly under natural conditions. widely planted grape variety in the world) was chosen mainly because it offers convenient possibilities of canopy manipulation, ranging from an open and exposed type architecture, to a closed and shaded configurations simply by moving inside or outside a «foldable Lyre» type trellis. Leaf water potential was measured throughou…