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1.
This study was carried out to determine the occurrence, prevalence and contributing factors to the incidence of goitre in
Yewa north local government area of Ogun state, southwestern Nigeria. To achieve these objectives, soil, water, and cassava
tubers were collected from four villages – Igbogila, Egua, Sawonjo and Imoto and from Lagos (about 250 m to the ocean) as
a reference location, in order to determine their iodine concentrations. The results of the analyses indicated a soil mean
iodine range of 2.1–5.8 μg g−1; a cassava mean iodine value of 2.3–3.5 μg g−1 and a drinking water mean iodine value of generally <1.0 μg L−1 in all the four villages. These values of iodine in soil and water of the four villages are considered low when compared
with the soil iodine value of 7.4 μg g−1 and water iodine value of 6.1 μg L−1 obtained from Lagos. The limestone unit of the study area remains an inhibiting factor in the bioavailability of the iodine
because of its alkalinity. Statistical analysis has shown that there was significant difference between iodine concentration
in the soils and the drinking water, and a correlation between the soil iodine and organic matter content at p < 0.05. The correlation between soil iodine and granulometric fractions occurred at p < 0.01. Potential goitrogens in the commonly consumed cassava products might also have contributed to the prevalence of goitre
in the study area. Both the females and the adults (i.e., less mobile groups) were found to be vulnerable to goitre development
in these villages. 相似文献
2.
3.
Concentrations of Fe, Mn, Zn, Pb, Cu and Cd in soil solutions taken in the vicinity of a sulphur mine range from 354 to 9080
μM L−1, and exceeded the concentrations measured in solutions from light acid arable soils. The content of each metal was a negative
function of either the solution pH or of Ca concentration.
Reclamation of S-contaminated soil by an application of 2000 tonnes of limestone per hectare did not significantly affect
the solubility of trace metals, whereas equilibration of soil samples with CaCO3 in the laboratory decreased solubility of metals, especially in the soil under moist conditions.
Sulphur deposition may modify the natural cycling of metals in soils. 相似文献
4.
Previous epidemiological studies have shown that dental fluorosis is endemic in the lowland, dry zone of Sri Lanka, which is considered to be an area in which excessive quantities of fluorides are present in the drinking water supplies. It has been found that kaolinitic clay forms a suitable raw material in the defluoridation of water.It is shown that there is a noticeable effect of selenium and media pH on the reactions involved in the interaction of fluoride with clay. In this study, 1 mM fluoride solutions containing SeO
3
2–
(selenite) concentrations of 0 mM, 0.1 mM, 0.5 mM and 1 mM were used in the reactions with kaolinitic clay. The effect of pH was monitored in the range 4 to 8. It was observed that fluoride adsorption was maximum at a pH of 5.6 without either SeO
3
2–
or SeO
4
2–
, the adsorption capacity being 15.2 mol F– g–1 clay. However, when the SeO
3
2–
concentration was increased up to 0.5 mM at this optimum pH, the adsorption capacity reduced to 12.8 mol F– g–1 clay. Monitoring of the effect of SeO
4
2–
and media pH on fluoride adsorption showed that when the SeO
4
2–
concentration increases from zero to 0.1 mM, there is a reduction of fluoride adsorption capacity. However, when the SeO
4
2–
concentration is further increased from 0.1 mM to 1.0 mM, there was an increase in the fluoride adsorption capacity, indicating a more consistent effect of SeO
3
2–
on fluoride-kaolinitic clay interaction than SeO
4
2–
.Fluoride concentrations in drinking water supplies have a marked effect on dental health and the geochemistry of selenium appears to play an important role in the geochemical mobility of fluoride ions. 相似文献
5.
Yinian Zhu Xuehong Zhang Honghu Zeng Huili Liu Na He Meifang Qian 《Environmental Chemistry Letters》2011,9(3):339-345
Svabite is a secondary arsenate mineral, calcium fluoride arsenate [Ca5(AsO4)3F], in the apatite group of phosphates. Its dissolution and subsequent release of aqueous species play an important role in
the cycling of arsenic and fluoride in the environment, but the thermodynamic and kinetic properties of svabite dissolution
have never been investigated. In the present study, svabite was prepared by precipitation and characterized by various techniques,
and then dissolution of synthetic svabite was studied at 25, 35 and 45°C in a series of batch experiments. In addition, the
aqueous concentrations from the batch dissolution were used to calculate the solubility product and free energy of formation
of svabite. The results of the X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy
analyses indicated that the synthetic, microcrystalline svabite with apatite structure used in the experiments has not changed
after dissolution. For the dissolution of svabite [Ca5(AsO4)3F] in ultrapure water, F− ions were initially found to dissolve preferentially when compared with calcium and arsenate. Preferential dissolution of
arsenate when compared with that of calcium was also observed. Dissolution of svabite in aqueous medium appeared to be always
non-stoichiometric at the beginning, but when a dissolution equilibrium or steady state was reached at 25 and 35°C, the solid
dissolved almost stoichiometrically. The release of calcium, arsenic and fluoride to solution increased with decreasing temperature.
The mean K
sp
value was calculated for Ca5(AsO4)3F of 10−39.21 (10−39.18 ~ 10−39.24) at 25°C; the free energy of formation ΔG
f
o
[Ca5(AsO4)3F] was −5210.46 kJ/mol. 相似文献
6.
I. Oller W. Gernjak M. I. Maldonado P. Fernández-Ibáñez J. Blanco J. A. Sánchez-Pérez S. Malato 《Environmental Chemistry Letters》2005,3(3):118-121
Titanium dioxide photocatalysis, using 200 mgl−1 of TiO2, and photo-Fenton, using 20 mg l−1 of iron, were applied to the treatment of dimethoate dissolved in water at 50 mg l−1. A heterogeneous photocatalysis test was performed in a 35-l solar pilot plant with Compound Parabolic Collectors (CPCs)
under natural illumination. A homogeneous photocatalysis test was performed in a different solar pilot plant with four CPC
units and a total volume of 75 l. In this work total disappearance of dimethoate and 90% of mineralization were attained in
both solar treatments. Treatment time, hydrogen peroxide consumption and ferric phosphate precipitation during photo-Fenton
treatment were discussed.
An erratum to this article can be found at 相似文献
7.
A health risk assessment for fluoride in Central Europe 总被引:4,自引:0,他引:4
Fordyce FM Vrana K Zhovinsky E Povoroznuk V Toth G Hope BC Iljinsky U Baker J 《Environmental geochemistry and health》2007,29(2):83-102
Like many elements, fluorine (which generally occurs in nature as fluoride) is beneficial to human health in trace amounts,
but can be toxic in excess. The links between low intakes of fluoride and dental protection are well known; however, fluoride
is a powerful calcium-seeking element and can interfere with the calcified structure of bones and teeth in the human body
at higher concentrations causing dental or skeletal fluorosis. One of the main exposure routes is via drinking water and the
World Health Organisation currently sets water quality guidelines for the element. In Central Europe, groundwater resources
that exceed the guideline value of 1.5 mg l−1 are widespread and effects on health of high fluoride in water have been reported. The aim of the current project was to
develop a geographic information system (GIS) to aid the identification of areas where high-fluoride waters and fluorosis
may be a problem; hence, where water treatment technologies should be targeted. The development of the GIS was based upon
the collation and digitisation of existing information relevant to fluoride risk in Ukraine, Moldova, Hungary and Slovakia
assembled for the first time in a readily accessible form. In addition, geochemistry and health studies to examine in more
detail the relationships between high-fluoride drinking waters and health effects in the population were carried out in Moldova
and Ukraine demonstrating dental fluorosis prevalence rates of 60–90% in adolescents consuming water containing 2–7 mg l−1 fluoride. 相似文献
8.
Analysis of the isotope composition of calcareous structures of marine organisms has proved useful in providing biological
data. The present study constitutes the first detailed work undertaken on the isotope composition of coleoid cephalopods.
We analysed the carbon- and oxygen-isotope composition [δ13C (CO2−
3) and δ18O (CO2−
3), respectively] of the cuttlebone aragonite of wild and cultivated specimens of Sepia officinalis Linnaeus, 1758. δ13C (CO2−
3) ranged from −2.94 to 1.00‰, δ18O (CO2−
3) from −0.18 to 2.08‰. The carbon-isotope composition is not in equilibrium with the carbon species of the ambient seawater,
and does not reflect the deposition of CaCO3 in seawater. The potential influence of environmental factors and biological processes on the carbon-isotope composition
of the cuttlebone is discussed. In contrast to δ13C, the oxygen-isotope composition of cuttlebone aragonite appears to be in isotopic equilibrium with the ambient seawater.
Seasonal changes in isotopic temperature revealed by our analyses agreed with changes in the temperature of the ambient seawater.
CaCO3 was deposited all year round. A maximum life span of 2 yr, a year-round spawning season, and variable growth rates among and
within individuals have been inferred from the isotopic temperatures.
Received: 14 April 1998 / Accepted: 26 November 1998 相似文献
9.
Airborne fluoride was determined in the rainwater, surface soil and groundwater along a gradient of emission of a phosphate
fertilizer factory in Rio Grande, southern Brazil. Concentrations of fluoride in rainwater and groundwater achieved 3 mg l−1 and 5 mg l−1, respectively, and were dependent on pH. The fluoride deposited from emissions accumulated in a superficial horizon of soil
in quantities comparable to those in the manufactured end-products—up to 23,000 mg kg−1. Fluoride distribution in the environment is controlled by physical–chemical parameters of emission, rain intensity and soil
properties. The highest fluoride concentrations were registered at a close distance of up to 2 km from the factory. The distribution
of fluoride in groundwater resembled the same distribution in rainwater due to the high permeability of the local soils. Fluoride
penetration to the groundwater also depended on the type of vegetation cover. The groundwater in woodland areas was less affected
by contamination of fluoride than in the grassland areas, most probably because of the influence of eucalyptus throughfall,
which increases the pH of wet precipitates. 相似文献
10.
The cancer risk and the non-cancer hazard index for inhabitants exposed to As, Cd, Cu and Zn in the soils and stream waters
of the abandoned Songcheon Au–Ag mine area were evaluated. Mean concentrations of As, Cd, Cu, Pb and Zn in agricultural soils
were 230, 2.5, 120, 160, and 164 mg kg−1, respectively. Mean concentrations of As, Cd and Zn of the water in the stream where drinking water was drawn was 246 μg
L−1, 161 μg L−1 and 3899 μg L−1, respectively. These levels are significantly higher than the permissible levels for drinking water quality recommended by
Korea and WHO. The resulting human health risks to farmers who inhabited the surrounding areas due to drinking water were
summarized as follows: (1) the non-cancer health hazard indices showed that the toxic risk due to As and Cd in drinking water
were 10 and 4 times, respectively, greater than those induced by the safe average daily dosages of the respective chemicals.
(2) the cancer risk of As for exposed individuals through the drinking water pathway was 5 in 1000, exceeded the acceptable
risk of 1 in 10,000 set for regulatory purposes. 相似文献
11.
The Contribution of Drinking Water towards Dental Fluorosis: A case study of Njoro Division, Nakuru District, Kenya 总被引:1,自引:0,他引:1
Wilkister K. Moturi Mwakio P. Tole Theo C. Davies 《Environmental geochemistry and health》2002,24(2):123-130
This study was carried out to measure the fluoride levels of water consumed in the Njoro division of Nakuru district, Kenya. The sources of drinking water, methods of water storage and utilisation, as well as the perceptions of the local community towards dental fluorosis and the percentage of children with moderate to severe dental fluorosis were also determined. Rainwater had mean fluoride levels of 0.5 mg L-1, dams 2.4 mg L-1, wells 4.1 mg L-1, springs 5.5 mg L-1, and boreholes 6.6 mg L-1. Water stored in plastic and cement containers did not show appreciable reduction in fluoride content with storage time; water stored in metal containers reduced fluoride by up to 8.2%; water stored in clay pots had the highest reduction in fluoride content, ranging between 34.3 and 64.7%;. Forty eight point three percent of children observed in the area had moderate to severe dental fluorosis, even though most people in the area did not know the cause of the problem.There is need to educate the community on the causes of fluorosis, and to lay strategies for addressing the issue, such as encouraging more rainwater harvesting, treating drinking water with alum, or using clay pots for storage of drinking water. 相似文献
12.
Meseret Dessalegne 《毒物与环境化学》2013,95(6):1056-1068
Dental and skeletal fluorosis is widespread in the Ethiopian Rift Valley region. Drinking water has been considered the main reason for the development of fluorosis, but dietary intake may also be a contributor in areas with high concentration of fluoride in water, soil, and biota. The purpose of this study is to assess the total daily dietary fluoride intake by adults in a rural part of the Ethiopian Rift Valley. The food, beverage, and water samples were collected from selected households of three neighboring villages with similar dietary pattern, but with different fluoride content in their water sources. Village A uses water with 1.0 mg L?1 fluoride, village B uses water with 3.0 mg L?1 fluoride, and village C uses water with 11.5 mg L?1 fluoride both for food preparation and for drinking. The level of fluoride was determined in all food ingredients, in the prepared food, beverages, and in the water used for food preparation and drinking. Recipe and food frequency questionnaires were used to gather household food preparation and consumption patterns. An alkali fusion method was used for digestion of food samples and for subsequent determination of fluoride with ion-selective electrode. The daily fluoride intake varied depending on its concentration in the water used for cooking and drinking. In households using water with 1 mg L?1, 3 mg L?1, and 11.5 mg L?1 fluoride, the total personal intake was found to be 10.5, 16.6, and 35.3 mg d?1, respectively. Contribution of the water to the daily fluoride intake was 33%, 58%, and 86%, respectively. Even in households using water containing fluoride at a concentration of 1 mg L?1, the daily intake was higher than the recommended safe intake of 1.5–4.0 mg d?1 for adults, which indicates that the fluoride intake through food may cause health risks. Minimizing the fluoride concentration in water to the lowest possible level will greatly reduce the daily intake. The form of fluorine (organic or inorganic) in the food items and the associated health risk factors need further investigation. 相似文献
13.
Fluoride concentration of groundwater reserves occurs in many places in the world. A critical area for such contamination
in India is alluvial soil of the plain region, consisting of five blocks (Jhajjar, Bahadurgarh, Beri, Matanhail, and Sahalawas)
of the Jhajjar District adjacent to the National Capital Territory of India, New Delhi. The purpose of this study was to assess
the association between water fluoride levels and prevalence of dental fluorosis among school children of the Jhajjar District
of Haryana, India. The fluoride content in underground drinking water sources was found to vary in villages. Hence, the villages
were categorized as high-fluoride villages (1.52–4.0 mg F/l) and low/normal-fluoride villages (0.30–1.0 mg F/l). The source
of dental fluorosis data was school-going children (7–15 years) showing different stages and types of fluorosis who were permanent
resident of these villages. The fraction of dental fluorosis-affected children varied from 30% to 94.85% in the high-fluoride
villages and from 8.80% to 28.20% in the low/normal-fluoride villages. The results of the present study revealed that there
existed a significant positive correlation between fluoride concentration in drinking water and dental fluorosis in high-fluoride
villages (r = 0.508; p < 0.001) and insignificant correlation in low-fluoride villages. 相似文献
14.
Enver Guler Deniz Ozakdag Muserref Arda Mithat Yuksel Nalan Kabay 《Environmental geochemistry and health》2010,32(4):335-339
The effect of feed seawater temperature on the quality of product water in a reverse osmosis process was investigated using
typical seawater at Urla Bay, Izmir region, Turkey. The tests were carried out at different feed seawater temperatures (11–23°C)
using two RO modules with one membrane element each. A number of variables, including pH, conductivity, total dissolved solids,
salinity, rejection percentage of a number of ions (Na+, K+, Ca2+, Mg2+, Cl−, HCO3
−, and SO4
2−), and the levels of boron and turbidities in collected permeates, were measured. The suitability of these permeates as irrigation
and drinking water was checked by comparison with water quality standards. 相似文献
15.
The geochemical characteristics of arsenic in the soil of the Western Hunan mining area of P.R. China were systematically
studied. The results show that the strata of Western Hunan are rich in arsenic and that Western Hunan is a geochemically abnormal
region for arsenic. The experimental study on speciation in the strata also indicates that the speciation of arsenic in the
Neoproterozoic-Cambrian strata are mainly easily transferred speciation (exchangeable, carbonate-bound, sulfides-bound), which
are approaching or exceed 60%. Arsenic content in the main soil of Western Hunan is in the range of 8.8–22.8 μg g−1, the mean value is 16.1 μg g−1, which is larger than the arsenic background value of Hunan soil. The distribution of rock with high arsenic content or high
easily transferred arsenic speciation is consistent with the distribution of high arsenic content soil. In the mining region,
part soils and river/brook waters were polluted by mine tailings and mining/smelting waste water. The arsenic content in polluted
paddy soils and river/brook water is 46.26–496.19 μg g−1, 0.3–16.5 mgL−1, respectively. The positive abnormality and pollution of arsenic in the soil and water affects the arsenic content of the
crop and the inhabitants’ health. 相似文献
16.
Surface waters in Scotland, notably from upland catchment areas, are commonly enriched in iron and organic acids. This study
investigated the impact of these species on the direct potentiometric determination of fluoride using a fluoride-selective
electrode. As the electrode technique is commonly used to monitor the fluoride content of potable waters, it is important
that these effects are evaluated if such waters are to be fluoridated.
The determination method used was that defined by Nicholson (1983) and Nicholson and Duff (1981) to minimise errors. This
employs the TISAB III-TAC buffer system with the following composition (in 1L): 58.0 g sodium chloride, 57.0 mL glacial acetic
acid, 4.0 g CDTA, 243.0 g tri-ammonium citrate adjusted to pH 5.4 with 10 M sodium hydroxide. Experimental solutions of fluoride
with organic acid or iron were prepared, and the effect on fluoride concentration determined for each combination. Concentrations
used: fluoride: 0.1, 1.0 mg L−1; humic acid: 5, 10, 100, 1000, 10,000 mg L−1; oxalic acid: 5, 10, 100, 1000, 10,000 mg L−1; iron(III): 1, 10, 100, 500 mg L−1;
Humic acid (HA) concentrations had no impact on the determination of fluoride at the 1.0 mg L−1 level. However, with 0.1 mg L−1; F−, an increase in the apparent fluoride concentration was observed when HA > 1,000 mg L−1; this increased with increasing HA content to a maximum of ∼600%. Oxalic acid (OA) generally had no impact on the fluoride
determinations at the 1.0 mg L−1; level, but at an OA concentration of 10,000 mg L−1; fluoride concentrations were reduced by ∼50%. At 0.1 mg L−1 F−, increasing OA concentrations produce a steady increase in the fluoride concentration of up to 200% with 1,000 mg L−1; OA, greater OA contents produce a fall in the fluoride content. Iron had no effect on the fluoride determinations at both
the 0.1 and 1.0 mg L−1 levels.
The causes of the apparent increases in fluoride concentration have not been determined, although fluoride contamination by
the reagents has been ruled-out. However, the results demonstrate that the defined method and buffer system is suitable for
the determination of fluoride in the presence of iron and organic acids at naturally occurring levels, and that fluoride will
not be masked from detection. 相似文献
17.
Ravi Naidu Euan Smith S. M. Imamul Huq Gary Owens 《Environmental geochemistry and health》2009,31(Z1):61-68
The bioavailability of arsenic (As) in the soil environment is largely governed by its adsorption–desorption reactions with
soil constituents. We have investigated the sorption–desorption behaviour of As in four typical Bangladeshi soils subjected
to irrigation with As-contaminated groundwater. The total As content of soils (160 samples) from the Laksham district ranged
from <0.03 to approximately 43 mg kg−1. Despite the low total soil As content, the concentration of As in the pore water of soils freshly irrigated with As-contaminated
groundwater ranged from 0.01 to 0.1 mg l−1. However, when these soils were allowed to dry, the concentration of As released in the pore water decreased to undetectable
levels. Remoistening of soils to field moisture over a 10-day period resulted in a significant (up to 0.06 mg l−1) release of As in the pore water of soils containing >10 mg As kg−1 soil, indicating the potential availability of As. In soils containing <5 mg As kg−1, As was not detected in the pore water. A comparison of Bangladeshi soils with strongly weathered long-term As-contaminated
soils from Queensland, Australia showed a much greater release of As in water extracts from the Australian soils. However,
this was attributed to the much higher loading of As in these Australian soils. The correlation of pore water As with other
inorganic ions (P, S) showed a strongly significant (P < 0.001) relationship with P, although there was no significant relationship between As and other inorganic cations, such
as Fe and Mn. Batch sorption studies showed an appreciable capacity for both AsV and AsIII sorption, with AsV being retained in much greater concentrations than AsIII. 相似文献
18.
Pankaj Kumar Manish Kumar A. L. Ramanathan Maki Tsujimura 《Environmental geochemistry and health》2010,32(2):129-146
Arsenic contamination in groundwater is of increasing concern because of its high toxicity and widespread occurrence. This
study is an effort to trace the factors responsible for arsenic enrichment in groundwater of the middle Gangetic Plain of
India through major ion chemistry, arsenic speciation, sediment grain-size analyses, and multivariate statistical techniques.
The study focuses on the distinction between the contributions of natural weathering and anthropogenic inputs of arsenic with
its spatial distribution and seasonal variations in the plain of the state Bihar of India. Thirty-six groundwater and one
sediment core samples were collected in the pre-monsoon and post-monsoon seasons. Various graphical plots and statistical
analysis were carried out using chemical data to enable hydrochemical evaluation of the aquifer system based on the ionic
constituents, water types, hydrochemical facies, and factors controlling groundwater quality. Results suggest that the groundwater
is characterized by slightly alkaline pH with moderate to strong reducing nature. The general trend of various ions was found
to be Ca2+ > Na+ > Mg2+ > K+ > NH4
+; and HCO3
− > Cl− > SO4
2− > NO3
− > PO4
3− > F− in both seasons. Spatial and temporal variations showed a slightly higher arsenic concentration in the pre-monsoon period
(118 μg/L) than in the post-monsoon period (114 μg/L). Results of correlation analyses indicate that arsenic contamination
is strongly associated with high concentrations of Fe, PO4
3−, and NH4
+ but relatively low Mn concentrations. Further, the enrichment of arsenic is more prevalent in the proximity of the Ganges
River, indicating that fluvial input is the main source of arsenic. Grain size analyses of sediment core samples revealed
clay (fine-grained) strata between 4.5 and 7.5 m deep that govern the vertical distribution of arsenic. The weathering of
carbonate and silicate minerals along with surface-groundwater interactions, ion exchange, and anthropogenic activities seem
to be the processes governing groundwater contamination, including with arsenic. Although the percentage of wells exceeding
the permissible limit (50 μg/L) was less (47%) than that reported in Bangladesh and West Bengal, the percentage contribution
of toxic As(III) to total arsenic concentration is quite high (66%). This study is vital considering that groundwater is the
exclusive source of drinking water in the region and not only makes situation alarming but also calls for immediate attention. 相似文献
19.
Wilson Y. Fantong Hiroshi Satake Samuel N. Ayonghe Emmanuel C. Suh Segun M. A. Adelana Emilia Bi S. Fantong Hycinth S. Banseka Cletus D. Gwanfogbe Leonard N. Woincham Yoshitoshi Uehara Jing Zhang 《Environmental geochemistry and health》2010,32(2):147-163
The 500,000 inhabitants of Mayo Tsanaga River Basin are vulnerable to a “silent” fluorosis from groundwater consumption. For the first time, the groundwater is investigated for the purpose of identifying the provenance of fluoride and estimating an optimal dose of fluoride in the study area. Based on the fluoride content of groundwater, fluorine and major oxides abundances in rocks from the study area, mean annual atmospheric temperature, and on-site diagnosis of fluorosis in children, the following results and conclusions are obtained: Fluoride concentration in groundwater ranges from 0.19 to 15.2 mg/l. Samples with fluoride content of <1.5 mg/l show Ca–HCO3 signatures, while those with fluoride >1.5 mg/l show a tendency towards Na-HCO3 type. Fluor-apatite and micas in the granites were identified as the main provenance of fluoride in the groundwater through water-rock interactions in an alkaline medium. The optimal fluoride dose in drinking water of the study area should be 0.7 mg/l, and could be adjusted downward to a level of 0.6 mg/l due to the high consumption rate of groundwater, especially during drier periods. 相似文献
20.
Rosborg I Nihlgård B Gerhardsson L Sverdrup H 《Environmental geochemistry and health》2006,28(3):215-229
The water chemistry of 20 municipal water treatment plants in southern Sweden, representing various bedrock situations, and water qualities, were investigated. Four water samples, raw and treated, were collected from each plant and analyzed by predominantly ICP-OES and ICP-MS at four occasions from June to December, 2001. The concentrations of Ca, Mg, K, Na, HCO3 and a number of micronutrients, varied considerably in treated waters from the studied plants (ranges; Ca: 9.1–53.7 mg L−1, Mg: 1.4–10.9 mg L−1, K: 1.1–4.8 mg L−1, Na; 5.4–75.6 mg L−1, HCO3: 27–217 mg L−1). The elimination of Fe and Mn from raw water was efficient in all treatments investigated, giving concentrations in treated waters below the detection limits at some plants. Softening filters gave waters with Ca-concentrations comparable to the softest waters in this study. Adjustment of pH by use of chemicals like lye, soda or lime, modified the consumer water composition significantly, besides raising the pH. It was estimated that drinking water contributed to approximately 2.2–13% of the daily Ca uptake, if the gastrointestinal uptake efficiency from food and water was estimated to be around 50%. The corresponding figures for Mg was 1.0–7% and for F 0–59%. None of the studied elements showed any significant time trends in raw or treated waters during the follow-up period. The concentrations of potentially toxic metals such as Al, Pb and U were low and did not indicate risks for adverse health effects (ranges; Al: 0.5–2.3 μg L−1, Pb: 0–0.3 μg L−1, U: 0.2.5 μg L−1). 相似文献