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1.
Concentrations of Ti, Ga, As, Sc, Zr, Sn, Hf, Th, U and Y have been determined for 70 paddy soils from 14 villages, selected throughout Sri Lanka by means of ICP-MS. The mean elemental contents of all paddy soil samples were 6120 Ti, 14.1 Ga, 0.84 As, 7.26 Sc, 129 Zr, 2.27 Sn, 3.64 Hf, 12.71 Th, 1.53 U, and 13.35 Y (all data in microg/g). Paddy soils were classified into groups based on morphology and climate. Higher contents of Th and U were found in the wet zone lowland soils whereas the higher Ti contents were observed in dry zone soils. Arsenic, Zr and Hf contents were comparatively similar in all regions. Factor analysis was used to identify the relationships between the contents of elements. 相似文献
2.
Chandrajith R Abeypala U Dissanayake CB Tobschall HJ 《Environmental geochemistry and health》2007,29(5):429-434
The purpose of this study was to assess the fluoride content of Ceylon Tea, which is a popular beverage throughout the world.
The fluoride content of tea infusions prepared from different grades of tea leaves collected from different parts of the tea-growing
regions (25 samples) of Sri Lanka was measured using a fluoride-selective electrode. Fluoride leaching was found to vary from
0.32 to 1.69 mg F/l, but there were no significant differences in terms of fluoride leaching between tea from different tea-growing
regions or between tea of different grades. Dental fluorosis is widespread throughout the dry zone of Sri Lanka, and drinking
water has traditionally been considered to be the main contributory factor to the development of fluorosis. However, diet,
the consumption of tea in particular, may also contribute to the manifestation of dental diseases. 相似文献
3.
Chandrajith R Kudavidanage E Tobschall HJ Dissanayake CB 《Environmental geochemistry and health》2009,31(3):391-400
Geophagy or deliberate ingestion of soils was observed among Asian elephants (Elephas maximus) in the Udawalwe National Park, Sri Lanka, for several years. The geochemical and mineralogical composition of the clayey
soil layers which are purposefully selected and eaten by elephants in the park were studied, in order to identify the possible
reasons for elephant geophagy. The concentrations of major and trace elements were determined by means of X-ray fluorescence
spectrometry in 21 soil samples from eight geophagic sites and six soil samples collected from four non-geophagic sites. The
mineralogical composition of selected soil samples was investigated using X-ray diffractometry (XRD). These geochemical analyses
revealed that geophagic soils in the study areas are deeply weathered and that most of the elements are leached from the soil
layers under extreme weathering conditions. The XRD data showed that the soils of the area consisted mainly quartz, feldspar,
and the clay minerals kaolinite, Fe-rich illite, and smectite. Although no significant geochemical differences were identified
between geophagic and non-geophagic soils, a clear difference was observed in their clay mineralogical content. Soils eaten
by elephants are richer in kaolinite and illite than non-geophagic soils, which contain a higher amount of smectite. It is
suggested that elephants in Udawalawe National Park ingest soils mainly not to supplement the mineral contents of their forage
but to detoxify unpalatable compounds in their diet. 相似文献
4.
J. F. W. Negendank H. Böhnel R. Emmermann R. Krawczyk F. Mooser S. Soto Pinieda H. J. Tobschall 《Die Naturwissenschaften》1982,69(3):130-139
It is reported about geological and petrological investigations on igneous rocks of the Eastern Trans-Mexican volcanic belt. The results seem to coincide with the hypothesis of the Cocosplate being subducted in NE direction. 相似文献
5.
Macroscopic and vibration spectroscopic evidence for specific bonding of arsenate on gibbsite 总被引:1,自引:0,他引:1
The As(V) adsorption onto gibbsite under different experimental conditions was examined. Macroscopic data suggests strong As(V) bonding on gibbsite possibly via a bidendate binuclear complexation mechanism. The As(V) adsorption was quantified with the charge distribution multi-site ions complexation (CD-MUSIC) model distributing the anion charge over 0- and 1-planes according to the modified Pauling's bond valence theory. In the dual-adsorbates system of As(III) and As(V), the As(III) adsorption was predicted up to pH 8 utilizing the binding constants derived for single-adsorbate data. However, with pH > 8, the modeled As(III) adsorption data is overestimating the experimental values. 相似文献
6.
YOAN PAILLET LAURENT BERGÈS JOAKIM HJÄLTÉN PÉTER ÓDOR CATHERINE AVON MARKUS BERNHARDT‐RÖMERMANN RIENK‐JAN BIJLSMA LUC DE BRUYN MARC FUHR ULF GRANDIN ROBERT KANKA LARS LUNDIN SANDRA LUQUE TIBOR MAGURA SILVIA MATESANZ ILONA MÉSZÁROS M.‐TERESA SEBASTIÀ WOLFGANG SCHMIDT TIBOR STANDOVÁR BÉLA TÓTHMÉRÉSZ ANNELI UOTILA FERNANDO VALLADARES KAI VELLAK RISTO VIRTANEN 《Conservation biology》2010,24(4):1157-1160
7.
The adsorptive interactions of Hg(II) with gibbsite-rich soils (hereafter SOIL-g) were modeled by 1-pK surface complexation theory using charge distribution multi-site ion competition model (CD MUSIC) incorporating basic Stern layer model (BSM) to account for electrostatic effects. The model calibrations were performed for the experimental data of synthetic gibbsite-Hg(II) adsorption. When [NaNO(3)] > or = 0.01M, the Hg(II) adsorption density values, of gibbsite, Gamma(Hg(II)), showed a negligible variation with ionic strength. However, Gamma(Hg(II)) values show a marked variation with the [Cl(-)]. When [Cl(-)] > or = 0.01M, the Gamma(Hg(II)) values showed a significant reduction with the pH. The Hg(II) adsorption behavior in NaNO(3) was modeled assuming homogeneous solid surface. The introduction of high affinity sites, i.e., >Al(s)OH at a low concentration (typically about 0.045 sites nm(-2)) is required to model Hg(II) adsorption in NaCl. According to IR spectroscopic data, the bauxitic soil (SOIL-g) is characterized by gibbsite and bayerite. These mineral phases were not treated discretely in modeling of Hg(II) and soil interactions. The CD MUSIC/BSM model combination can be used to model Hg(II) adsorption on bauxitic soil. The role of organic matter seems to play a role on Hg(II) binding when pH>8. The Hg(II) adsorption in the presence of excess Cl(-) ions required the selection of high affinity sites in modeling. 相似文献
8.
9.
The surface complexation of Cd(II) to goethite (α‐FeOOH) at varying concentrations of solid, background electrolyte and Cd(II) has been investigated. The data was quantified according to the generalized version of triple layer (TLM) surface complexation model. In the presence of atmospheric CO2, it was found that the experimental data of Cd(I) α‐FeOOH system could be explained satisfactorily by incorporating both the > FeOHCd+ and > FeOCdHCO3 in the calculations. However, at excessive concentrations of Cd(II), typically over 13% surface coverages, the TLM predictions significantly underestimated the experimentally observed data obtained for Cd(II)/α‐FeOOH systems. 相似文献
10.