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Journal ArticleDOI: 10.1016/J.JHAZMAT.2020.124694

Remediation of fluoride contaminated soil with nano-hydroxyapatite amendment: Response of soil fluoride bioavailability and microbial communities.

05 Mar 2021-Journal of Hazardous Materials (Elsevier)-Vol. 405, pp 124694
Abstract: Nano-hydroxyapatite (NHAP), possessing high defluoridation capacity, has been widely used to remove fluoride (F) from polluted water, but little is known about how it affects the bioavailability and toxicity of soil F towards plants. Here, the impact of NHAP (2% w/w) amendment on immobilization, speciation and accumulation of F was studied in a soil-plant system. The results revealed that the NHAP amendment worked effectively to reduce levels of water-soluble F (37.3%−87.8%) and increase available P (76.6%–147%). X-ray photoelectron spectroscopy analysis indicated that the formation of insoluble CaF2 and the ion exchange of F− with OH− into NHAP might be involved in the mechanism of F immobilization and soil pH elevation. Exposure to NHAP significantly decreased the abundance of Cyanobacteria in tested soils, and Gemmatimonadetes abundance in bulk soil was significantly higher than that in rhizosphere soil at 1,000 mg kg−1 F spiked level. Additionally, NHAP amendment decreased F accumulation in wheat shoots (9.10%–18.7%) and roots (3.88%–22.4%), which could mainly be attributed to the reduction of soil bioavailable F and the supplement of Ca from NHAP. These results suggest that NHAP could be a promising amendment to be applied to acidic soil contaminated with F.

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Topics: Bulk soil (55%), Soil pH (52%), Soil contamination (51%) ... read more
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9 results found


Journal ArticleDOI: 10.1016/J.SCITOTENV.2020.144809
Chun-dan Gan1, Zhiwei Gan1, Si-fan Cui1, Rui-jun Fan1  +3 moreInstitutions (1)
Abstract: Perfluorinated compounds (PFCs) are organo-fluorine compounds which have been identified at significant levels in soils due to their widespread usage in industrial and commercial applications. However, few studies are available regarding the occurrence of PFCs in the environment of endemic fluorosis areas. To address the issue, soils collected from an endemic fluorosis area of southwestern China were analyzed for the distribution of fluorine and 21 kinds of PFCs. The average water-soluble fluorine concentration in cultivated soil (4.87 mg kg−1) was significantly higher than that in uncultivated soil (3.15 mg kg−1), which mainly ascribed to the utilization of fluorine-enriched fertilizers during agricultural practices. Concentrations of ΣPFCs in all soils ranged from 0.508 to 6.83 ng g−1, with an average of 2.81 ng g−1, dominated by perfluorononanoic acid (PFNA) and perfluorooctanoic acid (PFOA). Highest ΣPFCs was found in the soil samples collected from cropland with intensive agricultural activities. Long-chain PFCs, including four perfluoroalkylcarboxylic acids (PFCAs, C ≥ 8) and one perfluoroalkylsulfonic acids (PFSAs) (perfluorooctane sulfonate (PFOS), C8), exhibited high levels in soils, probably due to their higher hydrophobicity and lower water-solubility than short-chain PFCs. While in sediments, short-chain PFCAs were the dominant compounds. Based on correlation analysis, the relationship between total fluorine and PFCs was insignificant, and soil organic matter was a relevant factor affecting PFCs distribution in soils. This study is expected to present a more comprehensive information about fluorine contamination under the influence of agricultural activities in an endemic fluorosis area.

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Topics: Soil organic matter (50%)

2 Citations


Open accessJournal ArticleDOI: 10.3390/CRYST11091124
15 Sep 2021-
Abstract: Adsorption and desorption properties of nano-hydroxyapatite (HAP) and silicon-modified hydroxyapatite (Si–HAP) were investigated with 4-aminopyridine (fampridine-4AP). The novelty of this research is the investigation of the suitability of the previously mentioned carriers for drug-delivery of 4AP. UV-VIS spectrophotometric results showed that the presence of silicon in the carrier did not significantly affect its adsorption capacity. The success of the adsorption was confirmed by thermal analysis (TG/DTA), scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD). Drug release experiments, performed in simulated body fluid (SBF), revealed a drug release from Si–HAP that was five times slower than HAP, explained by the good chemical bonding between the silanol groups of the carrier and the 4AP functional groups. The electrochemical measurements showed a value of the polarization resistance of the charge transfer (Rct) more than five times smaller in the case of Si–HAP coating loaded with 4AP, so the charge transfer process was hindered. The electrochemical impedance results revealed that electron transfer was inhibited in the presence of 4AP, in concordance with the previously mentioned strong bonds. The silicon substitution in HAP leads to good chemical bonding with the drug and a slow release, respectively.

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Topics: Drug carrier (55%), Simulated body fluid (51%), Fourier transform infrared spectroscopy (51%) ... read more

1 Citations


Journal ArticleDOI: 10.1002/TOX.23302
Ting Ouyang1, Yu Qin, Keke Luo1, Xue Han1  +3 moreInstitutions (1)
Abstract: Fluoride is a persistent environmental pollutant, and its excessive intake contributes to skeletal and dental fluorosis The mechanisms underlying fluoride-induced abnormal osteoblast proliferation and activation, which are related to skeletal fluorosis, have not yet been fully clarified As important epigenetic regulators, microRNAs (miRNAs) participate in bone metabolism On the basis of our previous miRNA-seq results and bioinformatics analysis, this study investigated the role and specific molecular mechanism of miR-486-3p in fluoride-induced osteoblast proliferation and activation via CyclinD1 Herein, in the fluoride-challenged population, we observed that miR-486-3p expression decreased while CyclinD1 and transforming growth factor (TGF)-β1 increased, and miR-486-3p level correlated negatively with the expression of CyclinD1 and TGF-β1 genes Further, we verified that sodium fluoride (NaF) decreases miR-486-3p expression in human osteoblasts and overexpression of miR-486-3p reduces fluoride-induced osteoblast proliferation and activation Meanwhile, we demonstrated that miR-486-3p regulates NaF-induced upregulation of CyclinD1 by directly targeting its 3'-untranslated region (3'-UTR) In addition, we observed that NaF activates the TGF-β1/Smad2/3/CyclinD1 axis and miR-486-3p mediates transcriptional regulation of CyclinD1 by TGF-β1/Smad2/3 signaling pathway via targeting TGF-β1 3'-UTR in vitro This study, thus, contributes significantly in revealing the mechanism of miR-486-3p-mediated CyclinD1 upregulation in skeletal fluorosis and sheds new light on endemic fluorosis treatment

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Topics: Skeletal fluorosis (58%), Sodium fluoride (53%), Osteoblast (53%) ... read more

1 Citations


Journal ArticleDOI: 10.1016/J.JFLUCHEM.2021.109883
Abstract: It has been established that fluoride bioavailability in the soil is defined by the form which it exists rather than the amount of total fluoride. In the soil, fluoride exist in different fractions such as water soluble (Ws-F), Exchangeable (Ex-F), bound to iron/manganese (Fe/Mn-F), organic matter bound (Or-F), and the residual (Res-F). All of these fractions are bioavailable however to different extents in an order Ws-F>Ex-F>Fe/Mn-F>Or-F>Res-F. Agricultural practices such as fertilizer application alters the behavior of these fractions which further affects fluoride bioavailability in the soil. This study investigated the influence of the three commonly used fertilizers (Di-ammonium Phosphate (DAP), Urea, and cow-manure) on the bioavailability of soil fluoride in an alkaline soil. The soil was mixed with either one of the fertilizers then incubated for a period of five months. All three fertilizers increased the amount of Ws-F by 7.8 ± 0.6, 4.1 ± 0.2, 9.6 ± 1.1 mg/kg and Fe/Mn-F by 2.24 ± 0.3, 0.44 ± 0.2, and 2.1 ± 0.2 mg/kg, for DAP, Urea, and manure amendments, respectively, but had no impact on the amount of Or-F. All three fertilizers were observed to enhance the bioavailability of fluoride in the soil by increasing the amount of Ws-F. The fertilizers could have increased the bioavailability of fluoride in the soil directly or indirectly through alteration of pH and the soil elemental composition. The three fertilizers might not be suitable for use in fluoride contaminated alkaline soils as they accelerate fluoride release and hence bioavailability in the soil.

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Topics: Fluoride (65%), Alkali soil (55%), Bioavailability (54%) ... read more

1 Citations


Journal ArticleDOI: 10.1016/J.JHAZMAT.2021.125899
Naiyi Yin1, Yunpeng Li1, Yang Yuting1, Chuanfang Fan1  +4 moreInstitutions (2)
Abstract: Incidental oral ingestion is considered to be an important exposure route for humans to soil contaminants, such as fluoride (F). For 25 soil samples containing 4000 mg F/kg from aluminium smelting site in southwestern China, this study investigated F bioaccessibility in the human gastrointestinal tract in vitro. Fluoride bioaccessibility (2.4–48.8%) in the gastric phase was primarily caused by the dissolution of F-Ca and F-Al compounds (assigned to residual phase), identified by X-ray photoelectron spectroscopy and sequential extraction. Following modification to the small intestinal phase, the variation in F bioaccessibility (2.5–38.8%) should be the result of concurrent processes, including the formation of F complexes and competitive adsorption, and inversely the precipitation of fluorite and surface adsorption of formed F–Al complexes. The colon incubation with human gut microbiota yielded a 1.3-fold increase in F bioaccessibility (3.9–45.7%), probably due to the dissolution of F bound to Fe (hydr)oxides. Bioaccessibility adjustment can reduce hazard quotient of fluoride, and non-carcinogenic risk for children should be noted that soil F intake contributed 21.7% on average, up to 76.6% of oral reference dose. This will result in better understanding of human health risk assessment associated with F exposures.

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Topics: Fluoride (54%)

1 Citations


References
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82 results found


Open accessJournal ArticleDOI: 10.1128/AEM.01996-06
Abstract: The assessment of microbial diversity and distribution is a major concern in environmental microbiology. There are two general approaches for measuring community diversity: quantitative measures, which use the abundance of each taxon, and qualitative measures, which use only the presence/absence of data. Quantitative measures are ideally suited to revealing community differences that are due to changes in relative taxon abundance (e.g., when a particular set of taxa flourish because a limiting nutrient source becomes abundant). Qualitative measures are most informative when communities differ primarily by what can live in them (e.g., at high temperatures), in part because abundance information can obscure significant patterns of variation in which taxa are present. We illustrate these principles using two 16S rRNA-based surveys of microbial populations and two phylogenetic measures of community β diversity: unweighted UniFrac, a qualitative measure, and weighted UniFrac, a new quantitative measure, which we have added to the UniFrac website (http://bmf.colorado.edu/unifrac). These studies considered the relative influences of mineral chemistry, temperature, and geography on microbial community composition in acidic thermal springs in Yellowstone National Park and the influences of obesity and kinship on microbial community composition in the mouse gut. We show that applying qualitative and quantitative measures to the same data set can lead to dramatically different conclusions about the main factors that structure microbial diversity and can provide insight into the nature of community differences. We also demonstrate that both weighted and unweighted UniFrac measurements are robust to the methods used to build the underlying phylogeny.

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Topics: UniFrac (68%)

1,492 Citations


Journal ArticleDOI: 10.1007/S11104-008-9833-8
01 Aug 2009-Plant and Soil
Abstract: Nitrogen is generally considered one of the major limiting nutrients in plant growth. The biological process responsible for reduction of molecular nitrogen into ammonia is referred to as nitrogen fixation. A wide diversity of nitrogen-fixing bacterial species belonging to most phyla of the Bacteria domain have the capacity to colonize the rhizosphere and to interact with plants. Leguminous and actinorhizal plants can obtain their nitrogen by association with rhizobia or Frankia via differentiation on their respective host plants of a specialized organ, the root nodule. Other symbiotic associations involve heterocystous cyanobacteria, while increasing numbers of nitrogen-fixing species have been identified as colonizing the root surface and, in some cases, the root interior of a variety of cereal crops and pasture grasses. Basic and advanced aspects of these associations are covered in this review.

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Topics: Frankia (63%), Rhizobia (62%), Root nodule (60%) ... read more

522 Citations


Journal ArticleDOI: 10.1007/S11157-008-9136-9
David L. Ozsvath1Institutions (1)
Abstract: The relationship between environmental fluoride and human health has been studied for over 100 years by researchers from a wide variety of disciplines. Most scientists believe that small amounts of fluoride in the diet can help prevent dental caries and strengthen bones, but there are a number of adverse affects that chronic ingestion at high doses can have on human health, including dental fluorosis, skeletal fluorosis, increased rates of bone fractures, decreased birth rates, increased rates of urolithiasis (kidney stones), impaired thyroid function, and lower intelligence in children. Chronic occupational exposure to fluoride dust and gas is associated with higher rates of bladder cancer and variety of respiratory ailments. Acute fluoride toxicity and even death from the ingestion of sodium fluoride pesticides and dental products have also been reported. The distribution of fluoride in the natural environment is very uneven, largely a result of the geochemical behavior of this element. Fluorine is preferentially enriched in highly evolved magmas and hydrothermal solutions, which explains why high concentrations are often found in syenites, granitoid plutonic rocks, alkaline volcanic, and hydrothermal deposits. Fluoride can also occur in sedimentary formations that contain fluoride-bearing minerals derived from the parent rock, fluoride-rich clays, or fluorapatite. Dissolved fluoride levels are usually controlled by the solubility of fluorite (CaF2); thus, high concentrations are often associated with soft, alkaline, and calcium-deficient waters. Although much is known about the occurrence and health effects of fluoride, problems persist in Third World countries, where populations have little choice in the source of their drinking water and food. However, even in developed nations, fluoride ingestion can exceed the recommended dose when sources other than drinking water are ignored.

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Topics: Fluoride toxicity (72%), Fluoride (69%), Skeletal fluorosis (57%) ... read more

396 Citations


Open accessJournal ArticleDOI: 10.1128/AEM.02012-06
Abstract: The abundance and composition of bacteria of the phylum Acidobacteria were surveyed in subsurface sediments from uranium-contaminated sites using amplification of 16S rRNA genes followed by clone/sequence analysis. Analysis of sequences from this study and public databases produced a revised and greatly expanded phylogeny of the Acidobacteria phylum consisting of 26 subgroups.

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Topics: Acidobacteria (72%), Phylum (58%)

293 Citations


Open accessJournal ArticleDOI: 10.1038/SREP05686
Ruiqiang Liu1, Rattan Lal1Institutions (1)
01 May 2015-Scientific Reports
Abstract: Some soluble phosphate salts, heavily used in agriculture as highly effective phosphorus (P) fertilizers, cause surface water eutrophication, while solid phosphates are less effective in supplying the nutrient P. In contrast, synthetic apatite nanoparticles could hypothetically supply sufficient P nutrients to crops but with less mobility in the environment and with less bioavailable P to algae in comparison to the soluble counterparts. Thus, a greenhouse experiment was conducted to assess the fertilizing effect of synthetic apatite nanoparticles on soybean (Glycine max). The particles, prepared using one-step wet chemical method, were spherical in shape with diameters of 15.8 ± 7.4 nm and the chemical composition was pure hydroxyapatite. The data show that application of the nanoparticles increased the growth rate and seed yield by 32.6% and 20.4%, respectively, compared to those of soybeans treated with a regular P fertilizer (Ca(H2PO4)2). Biomass productions were enhanced by 18.2% (above-ground) and 41.2% (below-ground). Using apatite nanoparticles as a new class of P fertilizer can potentially enhance agronomical yield and reduce risks of water eutrophication.

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Topics: Phosphorus (55%), Fertilizer (53%)

240 Citations