Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Molecules ; 29(11)2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38893574

RESUMO

Tourmaline, a boron-bearing mineral, has been extensively applied as a geothermometer, provenance indicator, and fluid-composition recorder in geological studies. In this paper, the decomposition capability of an HF-HNO3-mannitol mixture for a tourmaline sample was investigated in detail for the first time, and a wet acid digestion method based on the boron-mannitol complex for accurate boron determination in tourmaline by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. With a digestion temperature of 140 °C, tourmaline samples of 25 mg (±0.5 mg) can be completely decomposed by a ternary mixture, which consisted of 0.6 mL of HF, 0.6 mL of HNO3, and 0.7 mL of 2% mannitol (wt.), via a continuous heating treatment of 36 h. Following gentle evaporation at 100 °C, the sample residues were re-dissolved using 2 mL of 40% HNO3 solution (wt.) and diluted to about 2.0 × 105-fold by a two-step method using 2% HNO3 solution (wt.). The boron contents in a batch of parallel tourmaline samples were then determined by ICP-MS, and results showed that the boron concentration levels were in a range of 3.20-3.44% with determination RSDs less than 4.0% (n = 5). It was found that the boron concentrations obtained at the mass of 10B were comparable with results from the measurements at the mass of 11B. This revealed that the usage of 2% mannitol with a quantity as high as 0.7 mL in this developed approach did not exhibit significant effect on the quantification accuracy of boron at the mass of 11B. It was also found that the processes including fluoride-forming prevention and fluoride decomposition deteriorated the boron-reserving efficiency of mannitol for tourmaline, causing the averaged boron contents to vary from 2.25% to 3.57% (n = 5). Furthermore, the stability of the boron-mannitol complex under 185 °C by applying the laboratory high pressure-closed digestion method was evaluated, which showed that there existed a 60.36% loss of boron compared to that under 140 °C by using this proposed approach. For this ternary mixture, the tourmaline decomposing efficiency was found to be weakened prominently using 100 °C as the digestion temperature, and tourmaline powders can be observed even after 72 h of continuous heating with B contents within 1.09-1.23% (n = 5). To assess the accuracy of this developed method, the boron recovery of anhydrous lithium tetraborate was studied. It was found that the boron recoveries were within 96.59-102.12% (RSD < 1%, n = 5), demonstrating the accuracy and reliability of this proposed method, which exhibits advantages of high B preserving efficiency, and giving concentration information of both B and trace elements simultaneously. By applying such a boron-mannitol complex-based wet acid digestion method, the chemical composition of boron and trace elements in three tourmaline samples from different pegmatites were quantified, which provided valuable information to distinguish regional deposits and the associated evolution stages.

2.
Environ Monit Assess ; 194(11): 832, 2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36166099

RESUMO

The safety of drinking and irrigation water is an issue of great concern worldwide. The rational development and utilization of water resources are vital for the economic and societal stability of Altay, an extremely arid area. In this study, three types of water samples (25 river waters, 10 groundwaters, 6 lake waters) were collected from main rivers and lakes in Altay and analyzed for electrical conductivity, total dissolved solids, pH, major ions (i.e., K+, Na+, Ca2+, Mg2+, HCO3-, Cl-, SO42-, NO3-, NO2-, F-), and trace elements (i.e., Al, Li, B, Sc, Ti, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, I, Ba, U). The water quality index (WQI), hazard quotient, carcinogenic risk, Na percentage, and Na adsorption ratio were then calculated to evaluate the water quality for drinking and irrigation. The results showed that the main hydrochemical type of river waters and groundwaters was Ca-HCO3, whereas that of lake water was mainly Na-SO4. The WQIs (9.39-170.69) indicated that the water quality in Altay ranged from poor to excellent. The concentrations of As, Ni, and U need to be carefully monitored since their average carcinogenic risks (for all waters collected, for adults) reached 0.05686, 0.06801, and 0.14527 and exceeded the safety risk levels (10-4-10-6) by at least 568 times, 680 times, and 1452 times, respectively. The result of Na% and SAR indicated that lake waters (with Na% of 62.92 and SAR of 41.63) and groundwaters (with Na% of 37.88 and SAR of 5.58) in Altay were unsuitable for irrigation, while river water (with Na% of 29.24 and SAR of 3.33) could meet the irrigation quality requirements. The results of this study could help promote reasonable water resource use among three types of waters and population protection in Altay.


Assuntos
Água Subterrânea , Oligoelementos , Poluentes Químicos da Água , Adulto , China , Monitoramento Ambiental/métodos , Água Subterrânea/química , Humanos , Dióxido de Nitrogênio , Oligoelementos/análise , Poluentes Químicos da Água/análise , Qualidade da Água
3.
Environ Monit Assess ; 193(2): 81, 2021 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-33486598

RESUMO

Heavy metal and metalloid (HMM) contamination of the water environment caused by mining activities is a great challenge to the global mining industry. HMMs released by various mines could easily enter the surrounding environment and pose serious threats to human health. Although the HMM pollution of surface water in various mines has been widely researched, relevant studies on the effects of mining activities on the surface water of hard-rock-type Li mines are scarce. Herein, a total of 81 water samples were collected from Jiajika mine for the first time, the largest hard-rock-type Li mine in Asia. The physical parameters and concentrations of HMMs and major ions of the samples were analyzed to evaluate the water quality and HMM level of surface water. Results showed that (1) most of the parameters analyzed adhered to the strictest guidelines of Chinese surface waters and the drinking water guidelines of WHO, except Mn, Pb, and As of a few samples from tailings-affected areas and Li-bearing areas; (2) mineral tailings obviously increased the pH and decreased the dissolved oxygen (DO) of the surrounding surface waters; (3) the highest concentrations of As (5.58 µg/L), Zn (81.8 µg/L), Ba (5.26 µg/L), and Co (0.33 µg/L) were observed around the tailings reservoir, whereas the highest concentrations of Cr (1.5 µg/L), Mn (380 µg/L), Pb (28.4 µg/L), and V (3.16 µg/L) were observed in Li-bearing areas; and (4) according to the statistical results, the concentrations of As, Cr, Ni, and V in surface water were mainly affected by mining activities, whereas those of Cu, Zn, Ba, Co, and Pb were dominantly affected by natural processes. These results provide useful information about water quality in relation to Li mining and can help the government make reasonable decisions regarding hard-rock-type Li resource exploitation activities.


Assuntos
Metais Pesados , Poluentes do Solo , Poluentes Químicos da Água , Ásia , China , Monitoramento Ambiental , Humanos , Lítio , Metais Pesados/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise
4.
Guang Pu Xue Yu Guang Pu Fen Xi ; 34(5): 1158-62, 2014 May.
Artigo em Zh | MEDLINE | ID: mdl-25095398

RESUMO

In the present paper, ten aqueous samples which contain-different concentrations of REE were collected in south Jiangxi province, and the reflectance spectra and the concentrations of REE were measured by analytical spectral devices (ASD) FieldSpec-3 reflectance spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results show that the spectra presented mix characteristics of pure water and rare earth oxide. In addition, six diagnostic absorption features caused by REE in visible and near-infrared wavelengths were detected. Then, relative absorption depths of the six absorption wavelength were calculated by the ratio spectra of sample spectra and pure water spectra. Finally, concentrations of total REE of ten samples and relative absorption depths of the six absorption wavelength were selected as two factors, and their relationship was perfectly described using linear regression analysis in which correlation coefficient was up to 96%-97%. The study provides a new method for quantitative estimation of different concentrations of dissolved REE in aqueous media, and strengthens theoretical basis for hyperspectral information extraction of REE.

5.
J Affect Disord ; 355: 355-362, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38554881

RESUMO

BACKGROUND: An association between insulin resistance (IR) and depression has been identified in recent years. The purpose of this study was to examine the relationship between IR and depression in the general population. METHODS: The population for this cross-sectional study consisted of adults participating in the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2018. Insulin sensitivity was assessed using the Metabolic Score for IR (METS-IR) index, while depression was evaluated using the Patient Health Questionnaire (PHQ)-9. Logistic regression analyses, subgroup analyses, and dose-response curves were conducted to assess the association between the METS-IR index and depression. RESULTS: A total of 13,157 adults aged over 20 years were included in this study. After adjusting for potential confounders, it was observed that each unit increase in the METS-IR index was associated with a 1.1 percentage point increase in the prevalence of depression (OR = 1.011; 95 % CI: 1.008, 1.014). Patients in the 4th quartile of the METS-IR index had a higher likelihood of depression compared to those in the 1st quartile (OR = 1.386, 95 % CI: 1.239, 1.549). Stratified analyses demonstrated consistent results in all subgroups, except for men, patients under 40 years of age, and those with a history of cancer. Dose-response curves indicated a nonlinear relationship between the METS-IR index and the risk of depression, with an inflection point value of 32.443 according to threshold effect analysis. CONCLUSIONS: Our findings suggest that higher METS-IR scores are associated with an increased likelihood of experiencing depressive symptoms among U.S. adults.


Assuntos
Resistência à Insulina , Síndrome Metabólica , Adulto , Masculino , Humanos , Síndrome Metabólica/epidemiologia , Inquéritos Nutricionais , Depressão/epidemiologia , Estudos Transversais
6.
Huan Jing Ke Xue ; 43(8): 4179-4189, 2022 Aug 08.
Artigo em Zh | MEDLINE | ID: mdl-35971715

RESUMO

Shizuishan is a typical exhausted resources-based city in the northern area of the Ningxia Hui autonomous region in China. In order to develop the planting industry of selenium (Se)-rich agricultural products and promote green and sustainable urban development and transformation, investigations on the quality of Se-rich land were carried out in Shizuishan City, where 7399 surface soil (0-20 cm) samples of farmlands, 30 atmospheric precipitation samples, and nine parent rocks were collected. By means of semi variogram model construction by GS+, Kriging interpolation in ArcGIS and statistics via SPSS, such as correlation analysis and mean-value analysis, the content, spatial distribution, and enrichment factors of Se-soil were analyzed. Further, the enrichment characteristics of soil Se in alkaline conditions were summarized. The results indicated that ω(Se) in surface soil was (0.26±0.12) mg·kg-1, and its spatial distribution was highly auto-correlated. The variation in Se content was related to natural factors. Along Helan Mountain, the content of Se in the surface soil was comparatively higher than that where coal mines were located. The parent rock was the principal factor that controlled the enrichment of soil Se. The physical and chemical properties of soil such as organic material, pH, and iron and manganese oxides had crucial effects on the enrichment of soil Se in a surficial environment. Compared to a strong alkaline environment, alkaline conditions were beneficial for the enrichment of Se in the surface soil.


Assuntos
Selênio , Poluentes do Solo , China , Cidades , Fazendas , Solo/química , Poluentes do Solo/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA