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1.
The Salí River Basin in north-west Argentina (7,000 km2) is composed of a sequence of Tertiary and Quaternary loess deposits, which have been substantially reworked by fluvial and
aeolian processes. As with other areas of the Chaco-Pampean Plain, groundwater in the basin suffers a range of chemical quality
problems, including arsenic (concentrations in the range of 12.2–1,660 μg L−1), fluoride (50–8,740 μg L−1), boron (34.0–9,550 μg L−1), vanadium (30.7–300 μg L−1) and uranium (0.03–125 μg L−1). Shallow groundwater (depths up to 15 m) has particularly high concentrations of these elements. Exceedances above WHO (2011) guideline values are 100% for As, 35% for B, 21% for U and 17% for F. Concentrations in deep (>200 m) and artesian groundwater
in the basin are also often high, though less extreme than at shallow depths. The waters are oxidizing, with often high bicarbonate
concentrations (50.0–1,260 mg L−1) and pH (6.28–9.24). The ultimate sources of these trace elements are the volcanic components of the loess deposits, although
sorption reactions involving secondary Al and Fe oxides also regulate the distribution and mobility of trace elements in the
aquifers. In addition, concentrations of chromium lie in range of 79.4–232 μg L−1 in shallow groundwater, 129–250 μg L−1 in deep groundwater and 110–218 μg L−1 in artesian groundwater. All exceed the WHO guideline value of 50 μg L−1. Their origin is likely to be predominantly geogenic, present as chromate in the ambient oxic and alkaline aquifer conditions. 相似文献
2.
Pistón M Silva J Pérez-Zambra R Dol I Knochen M 《Environmental geochemistry and health》2012,34(2):273-278
A multicommutated flow system was designed and evaluated for the determination of total arsenic and selenium by Hydride Generation
Atomic Absorption Spectrometry (HG-AAS). It was applied to the determination of arsenic and selenium in samples of natural
and drinking water. Detection limits were 0.46 and 0.08 μg l−1 for arsenic and selenium, respectively; sampling frequency was 120 samples h−1 for arsenic and 160 samples h−1 for selenium. Linear ranges found were 1.54–10 μg l−1 (R = 0.999) for arsenic and 0.27–27 μg l−1 (R = 0.999) for selenium. Accuracy was evaluated by spiking various water samples and using a reference material. Recoveries
were in the range 95–116%. Analytical precision (s
r
(%), n = 10) was 6% for both elements. Compared with the Standard Methods, APHA, 3114B manual method, the system consumes at least
10 times less sample per determination, and the quantities of acid and reducing agent used are significantly lower with a
reduction in the generation of pollutants and waste. As an additional advantage, the system is very fast, efficient and environmentally
friendly for monitoring total arsenic and selenium levels in waters. 相似文献
3.
Understanding the mechanism of arsenic (As) mobilization from sediments to groundwater is important for water quality management
in areas of endemic arsenic poisoning, such as the Datong basin in northern China. The bulk geochemistry analysis of sediment
samples from three 50-m boreholes drilled specifically for this study at As-contaminated aquifers, the groundwaters of which
have an As concentration up to 1060 μg/l, revealed that the average bulk concentrations of major and trace elements of the
samples are similar to those of the average upper continental crust. The average As content of the sediment samples (18.7 mg/kg)
is higher than that of modern unconsolidated sediments (5–10 mg/kg). Moreover, the abundance of elements varied with grain
size, with higher concentrations in finer fractions of the sediments, such as silt and clay. The concentration of NH2OH–HCl-extracted iron (Fe) strongly correlated with that of extracted As, suggesting that Fe oxyhydroxides may be the major
sink of As in the aquifer. The results of microcosm experiments showed that As mobilization from sediments to groundwater
is probably mainly related to changes in the redox conditions, with moderately reducing conditions being favorable for As
release from sediments into groundwater. 相似文献
4.
In anoxic sediments, as those found in estuaries, the mobility of metals can be controlled by the formation of stable sulfide
complexes. The potential bioavailability of a metal can then be predicted on the basis of the acid volatile sulfide (AVS)
and simultaneously extracted metals (SEM) criterion. Distributions of AVS and SEM (Hg, Cu, Pb, Cd, Zn, and Ni) along the sediment
profiles were determined seasonally for three rivers that constitute the Santos-Cubat?o estuarine system (SE Brazil), which
is located in one of the most industrialized areas of Latin America. AVS and SEM concentrations varied significantly, from
0.04 to 31.9 μmol g−1 and 0.086–6.659 μmol g−1, respectively. The highest AVS levels in sediments were detected in the winter, whereas high SEM values predominated in the
summer. Considering SEM–AVS molar differences as a parameter to evaluate potential bioavailability, sediments nearest to the
industrial area represent higher risk to biota, especially during the summer. It is due to relatively low AVS values and not
necessarily high concentrations of metals. 相似文献
5.
Benni W. Hansen Guillaume Drillet Reinhardt M. Kristensen Thomas F. Sørensen Majken T. Tøttrup 《Marine Biology》2010,157(1):59-68
Close to 50 species of marine Calanoid copepods have been reported to produce diapause eggs (Engel and Hirche in J Plankton
Res 26:1083–1093, 2004); eggs that are viable but require a refractory phase before they hatch, sometimes after months. Diapause eggs are often
described as morphologically different with respect to egg membrane ultrastructure and having a thicker egg shell with surface
ornamentation as opposed to the smooth shell found in subitaneous eggs that hatch within days (Belmonte in J Mar Syst 15:35–39,
1998; Chen and Marcus in Mar Biol 127:587–597, 1997; Castro-Longoria in Crustaceana 74:225–236, 2001). Egg production rates, egg surface ornamentation, and hatching success were monitored in large aquaculture fish enclosures
during winter with close to zero water temperatures (N57°). Surprisingly, all female copepods (Acartia spp.—presumably A. tonsa, and Centropages hamatus) produced eggs all through the winter with no obvious pattern with respect to light, temperature and food availability, and
no diapause eggs were observed. However, individual females produced several categories of eggs with or without surface spines
even within the same egg batch as evidenced by scanning electron microscopy (SEM). Four egg categories were distinguishable:
‘no spines’, smooth eggs; ‘short spines’, 5–15 μm long; ‘truncated spines’, with the spine tips cut-off <10 μm long; and ‘long
spines’, up to 30 μm long. All egg categories remained unchanged with respect to surface structures from when we took them
out of the incubation bottles until they hatched. In general, the frequency of ‘no spines’ was 10–40%, and most eggs were
ornamented with ‘short-’ or ‘long spines’. Further, a given egg can be ornamented with all types of surface spines simultaneously,
which might even be a fifth egg category. The different egg categories were all able to hatch within days when exposed to
normoxic conditions suggesting that they were subitaneous. 相似文献
6.
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
7.
Dedication 总被引:1,自引:0,他引:1
Elevated concentrations of arsenic (As) occurred during warm months in water from the outlet of Lake Mohawk in northwestern
New Jersey. The shallow manmade lake is surrounded by residential development and used for recreation. Eutrophic conditions
are addressed by alum and copper sulfate applications and aerators operating in the summer. In September 2005, arsenite was
dominant in hypoxic to anoxic bottom water. Filterable As concentrations were about 1.6–2 times higher than those in the upper
water column (23–25 μg/L, mostly arsenate). Hypoxic/anoxic and near-neutral bottom conditions formed during the summer, but
became more oxic and alkaline as winter approached. Acid-leachable As concentrations in lake-bed sediments ranged up to 694 mg/kg
in highly organic material from the tops of sediment cores but were <15 mg/kg in geologic substrate. During warm months, reduced
As from the sediment diffuses into the water column and is oxidized; mixing by aerators, wind, and boat traffic spreads arsenate
and metals, some in particulate form, throughout the water column. Similar levels of As in sediments of lakes treated with
arsenic pesticides indicate that most of the As in Lake Mohawk probably derives from past use of arsenical pesticides, although
records of applications are lacking. The annual loss of As at the lake outlet is only about 0.01% of the As calculated to
be in the sediments, indicating that elevated levels of As in the lake will persist for decades. 相似文献
8.
Sensitive and selective determination of phenylhydrazine in the presence of hydrazine at a ferrocene-modified carbon nanotube paste electrode 总被引:1,自引:0,他引:1
Dariush Afzali Hassan Karimi-Maleh Mohammad Ali Khalilzadeh 《Environmental Chemistry Letters》2011,9(3):375-381
The determination of hydrazine derivatives is of special interest because they are toxic and widely used in industry, agriculture
and explosives. Electrochemical analysis has become of growing importance in industrial process control, environmental monitoring,
and different applications in medicine and biotechnology. In the present work, we used a carbon paste electrode modified by
ferrocene and carbon nanotubes for simultaneous determination of phenylhydrazine and hydrazine. The modified electrode showed
an excellent character for electrocatalytic oxidization of phenylhydrazine and hydrazine with a 310 mV separation of both
peaks. Differential pulse voltammetric peak currents of phenylhydrazine and hydrazine increased linearly with their concentrations
at the range of 0.85–700 and 16–800 μM, and the detection limits (3σ) were determined to be 0.6 and 14 μM, respectively. Here,
we show that this electrode could be used as an electrochemical sensor for determination of phenylhydrazine and hydrazine
in real samples (water and urine) with advantages such as short time of analysis, lack of pretreatment procedures and more
cheaper in comparison with some routine analysis methods such as chromatography or spectroscopy. The modified electrode showed
good reproducibility, remarkable long-term stability, and especially good surface renewability by simple mechanical polishing. 相似文献
9.
Asaad Ahmed Nafees Ambreen Kazi Zafar Fatmi Muhammad Irfan Arif Ali Fujio Kayama 《Environmental geochemistry and health》2011,33(2):203-216
This study was designed to determine the association between chronic arsenic exposure through drinking groundwater and decrement
in lung function, particularly among individuals who do not have signs of arsenic lesions, among an adult population. This
was a comparative cross-sectional study conducted during the months of January to March 2009. One hundred participants ≥15 years
of age in each group, i.e. exposed (≥100 μg/l) and unexposed (≤10 μg/l) to arsenic, determined by testing drinking water samples
(using portable kits), were compared for effects on lung function using spirometry. A structured and validated questionnaire
was administered. Examination for arsenic skin lesions was also done. There was a decline in the mean adjusted FEV1 of 154.3 ml
(95% CI: −324.7, 16.0; p = 0.076), in mean adjusted FVC of 221.9 ml (95% CI: −419.5, −24.3; p = 0.028), and in FEV1/FVC ratio of 2.0 (95% CI: −25.3, 29.4; p = 0.884) among participants who were exposed to arsenic compared to those unexposed. A separate model comprising a total
of 160 participants, 60 exposed to arsenic concentrations ≥250 μg/l and 100 unexposed at arsenic concentrations of ≤10 μg/l,
showed a decrement in mean adjusted FEV1 of 226.4 ml (95% CI: −430.4, −22.4; p = 0.030), in mean adjusted FVC of 354.8 ml (95% CI: −583.6, −126.0; p = 0.003), and in FEV1/FVC ratio of 9.9 (95% CI: −21.8, 41.6; p = 0.539) among participants who were exposed to arsenic in drinking groundwater. This study demonstrated that decrement in
lung function is associated with chronic exposure to arsenic in drinking groundwater, occurring independently, and even before
any manifestation, of arsenic skin lesions or respiratory symptoms. The study also demonstrated a dose-response effect of
arsenic exposure and lung function decrement. 相似文献
10.
Debapriya Mondal Mayukh Banerjee Manjari Kundu Nilanjana Banerjee Udayan Bhattacharya Ashok K. Giri Bhaswati Ganguli Sugata Sen Roy David A. Polya 《Environmental geochemistry and health》2010,32(6):463-477
Remediation aimed at reducing human exposure to groundwater arsenic in West Bengal, one of the regions most impacted by this
environmental hazard, are currently largely focussed on reducing arsenic in drinking water. Rice and cooking of rice, however,
have also been identified as important or potentially important exposure routes. Quantifying the relative importance of these
exposure routes is critically required to inform the prioritisation and selection of remediation strategies. The aim of our
study, therefore, was to determine the relative contributions of drinking water, rice and cooking of rice to human exposure
in three contrasting areas of West Bengal with different overall levels of exposure to arsenic, viz. high (Bhawangola-I Block,
Murshidibad District), moderate (Chakdha Block, Nadia District) and low (Khejuri-I Block, Midnapur District). Arsenic exposure
from water was highly variable, median exposures being 0.02 μg/kg/d (Midnapur), 0.77 μg/kg/d (Nadia) and 2.03 μg/kg/d (Murshidabad).
In contrast arsenic exposure from cooked rice was relatively uniform, with median exposures being 0.30 μg/kg/d (Midnapur),
0.50 μg/kg/d (Nadia) and 0.84 μg/kg/d (Murshidabad). Cooking rice typically resulted in arsenic exposures of lower magnitude,
indeed in Midnapur, median exposure from cooking was slightly negative. Water was the dominant route of exposure in Murshidabad,
both water and rice were major exposure routes in Nadia, whereas rice was the dominant exposure route in Midnapur. Notwithstanding
the differences in balance of exposure routes, median excess lifetime cancer risk for all the blocks were found to exceed
the USEPA regulatory threshold target cancer risk level of 10−4–10−6. The difference in balance of exposure routes indicate a difference in balance of remediation approaches in the three districts. 相似文献
11.
Roongnapa Apinan Soisunwan Satarug Ronnatrai Ruengweerayut Wiratchanee Mahavorasirikul Kesara Na-Bangchang 《Environmental geochemistry and health》2010,32(3):237-242
Cadmium is a toxin of increasing public health concern due to its presence in most human foodstuffs and in cigarette smoke.
Exposure to cadmium leads to tissue bioaccumulation and, in particular, has nephrotoxic effects. The aim of the present study
was to investigate the association between cadmium body burden and iron stores in a Thai population. A total of 182 healthy
adult Thai subjects of both genders (89 males, 93 females) aged between 18 and 57 years and weighing 40–95 kg were included
in this study. The total amounts of cadmium excreted in urine over 2 h (μg/g creatinine) were used as an index of long-term
cadmium exposure. Quantitation of cadmium was performed using electrothermal (graphite furnace) atomic absorption spectrometry.
The urinary cadmium excreted displayed a normal frequency distribution. The average urinary cadmium level did not exceed the
WHO maximum tolerable internal dose for the non-exposed population (2 μg/g creatinine). Body iron stores reflected by serum
ferritin levels did not show any correlation with cadmium burden in both males and females, although a relatively stronger
influence of body iron store status on cadmium burden was shown in females. When the levels of serum ferritin were stratified
into five levels (<20, 20–100, 101–200, 201–300, and >300 μg/l), a significant difference in total cadmium body burden was
observed between females and males only in the group with a low level of serum ferritin of <20 μg/l. The cadmium body burden
in females was about twice that in males in this group. 相似文献
12.
Mohammad Mahmudur Rahman Gary Owens Ravi Naidu 《Environmental geochemistry and health》2009,31(Z1):179-187
Chronic exposure to arsenic (As) causes significant human health effects, including various cancers and skin disorders. Naturally
elevated concentrations of As have been detected in the groundwater of Bangladesh. Dietary intake and drinking water are the
major routes of As exposure for humans. The objectives of this study were to measure As concentrations in rice grain collected
from households in As-affected villages of Bangladesh where groundwater is used for agricultural irrigation and to estimate
the daily intake of As consumed by the villagers from rice. The median and mean total As contents in 214 rice grain samples
were 131 and 143 μg/kg, respectively, with a range of 2–557 μg/kg (dry weight, dw). Arsenic concentrations in control rice
samples imported from Pakistan and India and on sale in Australian supermarkets were significantly lower (p < 0.001) than in rice from contaminated areas. Daily dietary intake of As from rice was 56.4 μg for adults (males and females)
while the total daily intake of As from rice and from drinking water was 888.4 and 706.4 μg for adult males and adult females,
respectively. From our study, it appears that the villagers are consuming a significant amount of As from rice and drinking
water. The results suggest that the communities in the villages studied are potentially at risk of suffering from arsenic-related
diseases. 相似文献
13.
M. J. Watts J. O’Reilly A. L. Marcilla R. A. Shaw N. I. Ward 《Environmental geochemistry and health》2010,32(6):479-490
A field method is reported for the speciation of arsenic in water samples that is simple, rapid, safe to use beyond laboratory
environments, and cost effective. The method utilises solid-phase extraction cartridges (SPE) in series for selective retention
of arsenic species, followed by elution and measurement of eluted fractions by inductively coupled plasma mass spectrometry
(ICP-MS) for “total” arsenic. The method is suitable for on-site separation and preservation of arsenic species from water.
Mean percentage accuracies (n = 25) for synthetic solutions of arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MA), and dimethylarsinic acid (DMA) containing 10 μg l−1 As, were 98, 101, 94, and 105%, respectively. Data are presented to demonstrate the effect of pH and competing anions on
the retention of the arsenic species. The cartridges were tested in the UK and Argentina at sites where arsenic was known
to be present in surface and groundwaters, respectively, at elevated concentrations and under challenging matrix conditions.
In Argentinean groundwater, 4–20% of speciated arsenic was present as MA and 20–73% as AsIII. In UK surface waters, speciated arsenic was measured as 7–49% MA and 12–42% DMA. Comparative data from the field method
using SPE cartridges and the laboratory method using liquid chromatography coupled to ICP-MS for all water samples provided
a correlation of greater than 0.999 for AsIII and DMA, 0.991 for MA, and 0.982 for AsV (P < 0.01). 相似文献
14.
A. H. M. Selim Reza Jiin-Shuh Jean Huai-Jen Yang Ming-Kuo Lee Hua-Fen Hsu Chia-Chuan Liu Yao-Chang Lee Jochen Bundschuh Kao-Hong Lin Chi-Yu Lee 《Environmental geochemistry and health》2011,33(3):235-258
Humic substances in groundwater and aquifer sediments from the arsenicosis and Blackfoot disease (BFD) affected areas in Bangladesh
(Bengal delta plain) and Taiwan (Lanyang plain and Chianan plain) were characterized using fluorescence spectrophotometry
and Fourier transform infrared (FT-IR) spectroscopy. The results demonstrate that the mean concentration of As and relative
intensity of fluorescent humic substances are higher in the Chianan plain groundwater than those in the Lanyang plain and
Bengal delta plain groundwater. The mean As concentrations in Bengal delta plain, Chianan plain, and Lanyang plain are 50.65 μg/l
(2.8–170.8 μg/l, n = 20), 393 μg/l (9–704 μg/l, n = 5), and 104.5 μg/l (2.51–543 μg/l, n = 6), respectively. Average concentrations and relative fluorescent intensity of humic substances in groundwater are 25.381 QSU
(quinine standard unit) and 17.78 in the Bengal delta plain, 184.032 QSU and 128.41 in the Chianan plain, and 77.56 QSU and
53.43 in the Lanyang plain. Moreover, FT-IR analysis shows that the humic substances extracted from the Chianan plain groundwater
contain phenolic, alkanes, aromatic ring and amine groups, which tend to form metal carbon bonds with As and other trace elements.
By contrast, the spectra show that humic substances are largely absent from sediments and groundwater in the Bengal delta
plain and Lanyang plain. The data suggest that the reductive dissolution of As-adsorbed Mn oxyhydroxides is the most probable
mechanism for mobilization of As in the Bengal delta plain. However, in the Chianan plain and Lanyang plain, microbially mediated
reductive dissolution of As-adsorbed amorphous/crystalline Fe oxyhydroxides in organic-rich sediments is the primary mechanism
for releasing As to groundwater. High levels of As and humic substances possibly play a critical role in causing the unique
BFD in the Chianan plain of SW Taiwan. 相似文献
15.
Particle size distribution and pollutants in road-deposited sediments in different areas of Zhenjiang,China 总被引:2,自引:0,他引:2
An understanding of road-deposited sediment (RDS) characteristics on an impervious surface is essential to estimate pollutant
washoff characteristics and to minimise the impacts of pollutants on the water environment. A total of 62 RDS samples were
collected from four different land-use types (commercial, residential, intense traffic and riverside park) in Zhenjiang City,
China. The samples were fractionated into seven grain-size classes and analysed for particle size distribution and concentrations
of pollutants. The samples are found to consist predominantly of fine particles (60–80%, <250 μm). The maximum mean concentrations
of zinc, lead and copper were 686.93, 589.19 and 158.16 mg/kg, respectively, with the highest metal concentrations found in
samples from the intense traffic area. The maximum mean contents of organic matter (12.55%), nitrogen (6.31 mg/g) and phosphorus
(5.15 mg/g) were found in samples from the commercial area. The concentrations of heavy metals were highest in the smallest
particle size fraction analysed (63 μm). The organic matter and nitrogen content generally increased with decreasing particle
sizes in the <500-μm particle size range. The results also revealed that most of the total nitrogen (TN) is attached to the
finer sediments and that to effectively reduce TN loads in particulates, treatment facilities must be able to remove the finer
particles (down to 125 μm for TN). 相似文献
16.
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
17.
Rachel Allibone Shane J. Cronin Douglas T. Charley Vince E. Neall Robert B. Stewart Clive Oppenheimer 《Environmental geochemistry and health》2012,34(2):155-170
Ambrym in Vanuatu is a persistently degassing island volcano whose inhabitants harvest rainwater for their potable water needs.
The findings from this study indicate that dental fluorosis is prevalent in the population due to fluoride contamination of
rainwater by the volcanic plume. A dental survey was undertaken of 835 children aged 6–18 years using the Dean’s Index of
Fluorosis. Prevalence of dental fluorosis was found to be 96% in the target area of West Ambrym, 71% in North Ambrym, and
61% in Southeast Ambrym. This spatial distribution appears to reflect the prevailing winds and rainfall patterns on the island.
Severe cases were predominantly in West Ambrym, the most arid part of the island, and the most commonly affected by the volcanic
plume. Over 50 km downwind, on a portion of Malakula Island, the dental fluorosis prevalence was 85%, with 36% prevalence
on Tongoa Island, an area rarely affected by volcanic emissions. Drinking water samples from West Ambrym contained fluoride
levels from 0.7 to 9.5 ppm F (average 4.2 ppm F, n = 158) with 99% exceeding the recommended concentration of 1.0 ppm F. The pathway of fluoride-enriched rainwater impacting
upon human health as identified in this study has not previously been recognised in the aetiology of fluorosis. This is an
important consideration for populations in the vicinity of degassing volcanoes, particularly where rainwater comprises the
primary potable water supply for humans or animals. 相似文献
18.
Residues of fluoroquinolones in marine aquaculture environment of the Pearl River Delta, South China 总被引:4,自引:0,他引:4
He X Wang Z Nie X Yang Y Pan D Leung AO Cheng Z Yang Y Li K Chen K 《Environmental geochemistry and health》2012,34(3):323-335
Concentrations and distributions of selected fluoroquinolones (norfloxacin, ciprofloxacin and enrofloxacin) in water, sediments
and nine kinds of fish species collected from 6 sites in two marine aquaculture regions of the Pearl River Delta, China, were
analyzed by using high-performance liquid chromatography with fluorescence detector (HPLC). The results showed that the concentrations
of ciprofloxacin and enrofloxacin were below the limits of quantification (LOQ) in all water samples except for norfloxacin.
Norfloxacin and ciprofloxacin concentrations ranged from 1.88 to 11.20 ng g−1 dry wt, 0.76–2.42 ng g−1 dry wt in sediments collected from the Dapeng’ao region (sites 1–3) and ranged from 2.31 to 4.75 ng g−1 dry wt, 1.26–1.76 ng g−1 dry wt in sediments collected from the Hailing Island region (sites 4–6), respectively. However, no enrofloxacin was found
in all sediment samples. The three fluoroquinolones (FQs) were detected in all fish samples, and the concentrations were higher
in liver tissues than those in muscle tissues. The levels of norfloxacin were higher than ciprofloxacin and enrofloxacin in
both liver and muscle tissues. Among the nine marine fish species, Siganus fuscescens from Hailing Island had a significantly high level of norfloxacin in liver tissue (254.58 ng g−1 wet wt), followed by Sparus macrocephalus (133.15 ng g−1 wet wt) from Dapeng’ao, and the lowest value was Lutianus argentimaculatus (5.18 ng g−1 wet wt) from Hailing Island. The obtained results of FQs in present study do not represent a risk to the human health in
Guangdong coastal area, based on the maximum residue limits (MRLs) established by Chinese Government and the acceptable daily
intake (ADI) recommended by the Food and Agriculture Organization and World Health Organization (FAO/WHO). 相似文献
19.
Incidental soil ingestion is a common contaminant exposure pathway for humans, notably children. It is widely accepted that
the inclusion of total soil metal concentrations greatly overestimates the risk through soil ingestion for people due to contaminant
bioavailability constraints. The assumption also assumes that the contaminant distribution and the bioaccessible fraction
is consistent across all particle sizes. In this study, we investigated the distribution of arsenic across five particle size
fractions as well as arsenic bioaccessibility in the <250-, <100-, <10- and 2.5-μm soil particle fractions in 50 contaminated
soils. The distribution of arsenic was generally uniform across the larger particle size fractions but increased markedly
in the <2.5-μm soil particle fraction. The marked increase in arsenic concentration in the <2.5-μm fraction was associated
with a marked increase in the iron content. Arsenic bioaccessibility, in contrast, increased with decreasing particle size.
The mean arsenic bioaccessibility increased from 25 ± 16% in the <250-μm soil particle fraction to 42 ± 23% in the <10-μm
soil particle fraction. These results indicate that the assumption of static arsenic bioaccessibility values across particle
size fractions should be reconsidered if the ingested material is enriched with small particle fractions such as those found
in household dust. 相似文献
20.
Miriam Schutter Sander Kranenbarg René H. Wijffels Johan Verreth Ronald Osinga 《Marine Biology》2011,158(4):769-777
In this study, we tested the hypothesis that the importance of water flow for skeletal growth (rate) becomes higher with increasing
irradiance levels (i.e. a synergistic effect) and that such effect is mediated by a water flow modulated effect on net photosynthesis.
Four series of nine nubbins of G. fascicularis were grown at either high (600 μE m−2 s−1) or intermediate (300 μE m−2 s−1) irradiance in combination with either high (15–25 cm s−1) or low (5–10 cm s−1) flow. Growth was measured as buoyant weight and surface area. Photosynthetic rates were measured at each coral’s specific
experimental irradiance and flow speed. Additionally, the instantaneous effect of water flow on net photosynthetic rate was
determined in short-term incubations in a respirometric flowcell. A significant interaction was found between irradiance and
water flow for the increase in buoyant weight, the increase in surface area, and specific skeletal growth rate, indicating
that flow velocity becomes more important for coral growth with increasing irradiance levels. Enhancement of coral growth
with increasing water flow can be explained by increased net photosynthetic rates. Additionally, the need for costly photo-protective
mechanisms at low flow regimes could explain the differences in growth with flow. 相似文献