Fluoride Pollution Research Articles

ASSESSMENT OF FLUORIDE CONTENT IN THE RIVER WATER UZH AND LATORITSIA

The fluoride content in the waters of the Uzh and Latorytsia rivers was assessed (2020, all seasons). The basins of the studied rivers have complex tectonics and geology. It was found that the total content of fluorides in the water of the Uzh River is low (23.7-61.5 μg×L-1) and relatively stable over time. There are no natural and anthropogenic sources of fluoride pollution of river water. Variation of the total content of fluorides in water downstream occurs due to the geochemical characteristics of the river basin. The highest fluoride content is observed near the Uzhhorod city. It is shown that the content of biologically available forms (not chemically bonded) of fluorides in the water of the Uzh River is extremely low (2.2-4.8 μg×L-1). This can lead to fluoride deficiency in the region's residents, who use the Uzh River water as a source of drinking water.
 The total content of fluorides in the water of the Latorytsia River varies between 31.4-67.6 μg×L-1, which is to some extent comparable to the content in the Uzh River. Variation of fluoride content along the river is due to the geochemical characteristics of the river basin, the highest fluoride content in the water of the Latorytsia River is observed near Mukachevo city. It was also found that the content of biologically available forms of fluorides in the water of the Latorytsia River is extremely low (2.9-5.6 μg×L-1). Therefore, if the residents of the region use the water of the Latorytsia River as a source of drinking water, fluoride deficiency is possible. In general, the content of fluorides in the river waters of the Transcarpathian region is relatively low. The results of the research will be used for the planning the diet of residents of these regions of Transcarpathia.

Influence of the water–sediment interaction on the major ions chemistry and fluoride pollution in groundwater of the Older Alluvial Plains of Delhi, India

Influence of the water–sediment interaction on the major ions chemistry and fluoride pollution in groundwater of the Older Alluvial Plains of Delhi, India

Isolation and identification of high fluoride resistant bacteria from water samples of Dindigul district, Tamil Nadu, South India.

Fluoride (F - ) pollution is one of the major issues in India and worldwide. Water samples were collected, and analyse the physicochemical characteristics. From the results, acceptable limit pH ranges, low and high electrical conductivity (EC) values, high-level of TDS (total dissolved solids) and chloride (Cl-) values, less than desirable and higher than permissible F - concentrations (4.7 and 11 ppm) were found. At first, ninety-three colonies were screened using rapid hicoliform agar plates. After that, sixty-six F - resistant colonies were picked up from 50 mM NaF (Sodium fluoride) containing LB agar plates. Finally, eight isolates were showing a high degree of F - resistance (200--300mM NaF) and selected for further studies. High F - resistance isolates exhibited β and γ-haemolytic activities were determined in blood agar plates. F - resistant isolates showed their salt tolerances ranged from 4% to 7% NaCl and resistant to multiple antibiotics. Biochemical and 16S rRNA sequencing results showed that the F - resistant isolates were identified as Enterobacter cloacae strain 3, E. hormaechei strain 14, Enterobacter sp. strain 21, E. hormaechei strain 22, E. coli strain S2-9, Aeromonas caviae strain 31, A. caviae strain 32, A. caviae strain 34. All strains were submitted in the NCBI database with the accession numbers (MW131637, MW131639; MW131650-655). The F - resistant gene 'crcB' gene was successfully amplified from the resistant isolates using gene-specific primers. These results have demonstrated that fluoride resistant bacteria would be useful for bacterial fluoride bioremediation near future.

Fabrication of Manganese-Supported Activated Alumina Adsorbent for Defluoridation of Water: A Kinetics and Thermodynamics Study

Fluoride pollution frequently occurs in many underground drinking water sources due to discrepancies in the geological environment. To address this problem, a manganese-supported activated alumina (MnOOH-supported AA) adsorbent was proposed in the present study. The adsorbent was prepared with an impregnation method, then the morphology and microstructure were systematically characterized. Further, the adsorption kinetics and thermodynamics were systematically explored through static experiments to confirm the adsorption mechanism. The results showed that MnOOH was successfully loaded on the activated alumina (AA), and irregular and convex spinous structures were formed on the surface of particles. Compared with the AA, MnOOH-supported AA exhibited a significantly higher defluoridation rate, which has been doubled. The kinetic behavior of fluoride adsorption on MnOOH-supported AA was governed by the quasi-second-order kinetics model with regression coefficients of 0.9862, 0.9978 and 0.9956, respectively. The adsorption rate was mainly ascribed to the intra-particle diffusion. Additionally, the Freundlich isotherm equation fitted the adsorption thermodynamic process reasonably well compared with the Langmuir adsorption model. Specifically, the correlation coefficients were 0.9614, 0.9383 and 0.9852 at 25 °C, 35 °C and 45 °C, respectively. The adsorption–desorption isotherm plot was similar to the Type V isotherm. The whole fluoride adsorption was a spontaneous endothermic reaction, and controlled by chemical adsorption. These results demonstrated that MnOOH-supported AA as an alternative to the conventional AA showed promising potential for defluoridation in drinking water treatment.

Long-term exposure to the fluoride blocks the development of chondrocytes in the ducks: The molecular mechanism of fluoride regulating autophagy and apoptosis

Long-term exposure to excessive fluoride causes chronic damage in the body tissues and could lead to skeletal and dental fluorosis. Cartilage damage caused by excessive fluoride intake has gained wide attention, but how fluoride accumulation blocks the development of chondrocytes is still unclear. Here, we report a negative correlation between the length and growth plate width after NaF treatments via apoptosis and autophagy, with shrinkage of cells, nuclear retraction, dissolution of chondrocytes. Whereas, fluoride exposure had no significant effect on the number and distribution of the osteoclasts which were well aligned. More importantly, fluoride exposure induced apoptosis of tibial bone through CytC/Bcl-2/P53 pathways via targeting Caspase3, Caspase9, Bak1, and Bax expressions. Meanwhile, the Beclin1, mTOR, Pakin, Pink, and p62 were elevated in NaF treatment group, which indicated that long-term excessive fluoride triggered the autophagy in the tibial bone and produced the chondrocyte injury. Altogether, fluoride exposure induced the chondrocyte injury by regulating the autophagy and apoptosis in the tibial bone of ducks, which demonstrates that fluoride exposure is a risk factor for cartilage development. These findings revealed the essential role of CytC/Bcl-2/P53 pathways in long-term exposure to fluoride pollution and block the development of chondrocytes in ducks, and CytC/Bcl-2/P53 can be targeted to prevent fluoride induced chondrocyte injury.

Maghemite nano-fertilization promotes fluoride tolerance in rice by restoring grain yield and modulating the ionome and physiome

The present manuscript elucidated the ameliorative potential of nano-maghemite (FeNPs) against the hazardous effects of fluoride toxicity in the sensitive rice cultivar, IR-64. Fluoride pollution triggered bioaccumulation in root, shoot and spikelets which inhibited reproduction, agronomic development and mineral uptake. Suppressed activity of enzymatic antioxidants and excessive cobalt translocation manifested severe ROS-induced oxidative injuries. Seedling priming with FeNPs reduced fluoride bioaccumulation and promoted efficient uptake of macroelements and micronutrients like potassium, calcium, iron, zinc, copper, nickel, manganese, selenium and vanadium and reduced the translocation of cobalt in mature seedlings during stress. This altogether triggered growth and activated the enzymes like SOD, CAT, APX and GPOX. High accumulation of non-enzymatic antioxidants like proline, anthocyanins, flavonoids, phenolics along with stimulated GSH synthesis (determined from high GR, GST and GPX activity) and glyoxalase activity enabled FeNP-pulsed plants to efficiently scavenge ROS, O2-, H2O2 and methylglyoxal, and mitigate oxidative injuries. The ROS production was also lowered due to suppressed NADPH oxidase activity. This ensured subsequent revitalization of Hill activity and the level of photosynthetic pigments. Due to reduced fluoride partitioning and improved nutritional sink, the grain and panicle development in FeNP-primed, stressed seedlings were more stimulated than even control sets. Overall, our findings supported by statistical modelling established the potential of iron-nanotechnology in promoting safe rice cultivation even in fluoride-polluted environments.

Prevention Techniques of Nitrate and Fluoride Pollution and Advances in Water Treatment

Prevention Techniques of Nitrate and Fluoride Pollution and Advances in Water Treatment - written by Muhammad Tariq Bashir published on 2021/01/28 download full article with reference data and citations

Groundwater fluoride chemistry and health risk assessment of multi-aquifers in Jilin Qianan, Northeastern China

Groundwater from deep confined aquifers is often recommended for use because of it's low fluoride health risk. Thus, this study appraised groundwater fluoride hydrochemistry in a multi-aquifer system in Jilin Qianan to determine the non-carcinogenic health risk liable from exploiting the respective aquifers. 124 samples collected from the tertiary confined aquifer (N), quaternary confined aquifer (Q1), and quaternary phreatic aquifer (Q3) during surveys in 2001 and 2017 was analyzed using hydrochemical, statistical, spatial, and health risk assessment methods. Results show that the dominant water facies in the respective aquifer layers was Na+K–HCO3+CO3 except in Q1, where Ca+Mg – HCO3 + CO3 was marginally dominant. Fluoride concentrations outside the recommended guideline occurred in all the aquifers except N, where concentrations were optimum. The mean fluoride concentration of groundwater in the aquifers was of the order Q3 (2017) > Q3 (2001) > Q1 > N ( mean 2.09, 2.03, 1.41 and 0.75 mg/L with 51.85%, 57.44%, 36.36% and 0% occurring beyond recommended guideline values respectively). Silicate weathering, cation exchange, and fluorite dissolution in an alkaline environment were the significant fluoride contributing processes. Evaporation and MgF+ complex additionally influenced Q1 and Q3 (2017). The total hazard quotient (THQ) from oral and dermal pathways shows fluoride health risks in the order: infant > children > adult. The associated risks likely from using water in the respective aquifer layers is of the order Q3 (2017) > Q3 (2001) > Q1 > N. The mean groundwater fluoride in 2017 was marginally higher than that of 2001 ( 2.09>2.03 mg/L respectively) although the percentage of age group members disposed to fluoride risk from using water from Q3 decreased from 2001 to 2017. Knowledge of local hydrogeology in exploiting deep groundwater free of fluoride pollution and on-site defluoridation treatment of groundwater was recommended in the study area and other areas with similar characteristics.

Curcumin suppresses cell growth and attenuates fluoride-mediated Caspase-3 activation in ameloblast-like LS8 cells.

The trace element fluoride can be beneficial for oral health by preventing dental caries. However, fluoride is also known as an environmental pollutant. Fluoride pollution can lead to fluoride over-ingestion and can cause health issues, including dental fluorosis. Curcumin attenuated fluoride-induced toxicity in animal models, however the molecular mechanisms of how curcumin affects fluoride toxicity remain to be elucidated. We hypothesized that curcumin attenuates fluoride toxicity through modulation of Ac-p53. Here we investigated how curcumin affects the p53-p21 pathway in fluoride toxicity. LS8 cells were treated with NaF with/without curcumin. Curcumin significantly increased phosphorylation of Akt [Thr308] and attenuated fluoride-mediated caspase-3 cleavage and DNA damage marker γH2AX expression. Curcumin-mediated attenuation of caspase-3 activation was reversed by Akt inhibitor LY294002 (LY). However, LY did not alter curcumin-mediated γH2AX suppression. These results suggest that curcumin inhibited fluoride-mediated apoptosis via Akt activation, but DNA damage was suppressed by other pathways. Curcumin did not suppress/alter fluoride-mediated Ac-p53. However, curcumin itself significantly increased Ac-p53 and upregulated p21 protein levels to suppress cell proliferation in a dose-dependent manner. Curcumin suppressed fluoride-induced phosphorylation of p21 and increased p21 levels within the nuclear fraction. However, curcumin did not reverse fluoride-mediated cell growth inhibition. These results suggest that curcumin-induced Ac-p53 and p21 led to cell cycle arrest, while curcumin attenuated fluoride-mediated apoptosis via activation of Akt and suppressed fluoride-mediated DNA damage. By inhibiting DNA damage and apoptosis, curcumin may potentially alleviate health issues caused by fluoride pollution. Further studies are required to better understand the mechanism of curcumin-induced biological effects on fluoride toxicity.

Distribution, occurrence mechanisms, and management of high fluoride levels in the water, sediment, and soil of Shahu Lake, China

Fluoride (F−) pollution is a serious global problem. However, relatively few studies have evaluated the occurrence mechanisms of F− from an entire lake system perspective and determined their major causes via quantitative analysis. This study analyzes the distribution and occurrence mechanisms of F− in the lake water, sediment, groundwater, and soil of Shahu Lake, as well as assessing the influence of the factors on the F− in the lake water via quantitative analysis. Our results show that the F− concentrations in groundwater are higher in the eastern area of the lake, which is different from that in the surface soil layer. The F− concentrations in the lake water vary from 0.95 to 1.40 mg/L, most of which exceed Chinese standards (1 mg/L). Groundwater F− concentrations at 35% of the sampling sites exceed 1 mg/L. The total F− in the soil is significantly higher than the global mean. Ca2+-deficiency (which is mainly accelerated by cation exchange between Ca2+ and Na+) together with alkaline water conditions and intense evaporation are the major contributors of F− enrichment in groundwater. The groundwater hydrochemistry is suitable for the dissolution of F−-bearing minerals. The F− in soil is not easily leached into groundwater. Approximately 6.96 t of F− is deposited into Shahu Lake annually, where 79.17% of the F− originates from water recharge. Evaporation is the main direct cause of high F− concentrations in the lake, whereas water recharge and obstructed surface water exchange are indirect causes. To effectively decrease the F− concentrations in the lake water, water exchange within the Shahu Lake system should be enhanced, or at least 4.42 million m3 of lake water should be pumped out of the system before anthropogenic water recharge, with identically increasing volumes.

Development of a novel Artemia eggshell-zirconium nanocomposite for efficient fluoride removal.

Fluoride pollution in water has attracted widespread concern worldwide. In this study, an Artemia eggshell-zirconium (Aes-Z) nanocomposite has been used for fluoride removal. Material characterization results showed that nano-ZrO2 was immobilized on the inner surface of the Artemia eggshell, and there was no pore blockage on the composite material. Various parameters influencing on the fluoride removal, including treatment time, composite dosage, pH, initial fluoride concentration, and other anions, were analyzed. The removal efficiency of the composite material was better than that of the single zirconia material. The removal percentage of fluoride reached 93% in 30 min with an initial fluoride concentration of 10 mg/L and a nanocomposite dosage of 8.0 g/L. The composite material had a high removal efficiency for fluoride in the pH region 4.0–10.0. The adsorption of fluoride was not influenced by the common anions (e.g., Cl-, SO42-, and NO3-) in water. The regeneration revealed that the Aes-Z composite material could be reused and remove fluoride effectively in four cycles. The pseudo-second-order rate model adequately represented the adsorption kinetics of the Aes-Z composite material. A possible, defluoridation mechanism of the Aes-Z composite material was also proposed. This study demonstrates that Aes-Z is a promising adsorbent material for fluoride removal.

Potential Human Health Risks Due to Groundwater Fluoride Contamination: A Case Study Using Multi-techniques Approaches (GWQI, FPI, GIS, HHRA) in Bilate River Basin of Southern Main Ethiopian Rift, Ethiopia.

The main focus of the present research was to examine the appropriateness of groundwater resources for drinking purposes in the Bilate River Basin of Southern Main Ethiopian Rift, Ethiopia. The groundwater quality index (GWQI), fluoride pollution index (FPI), and human health risk were usedto examine the human health risk factors associated with the intake of high fluoride groundwater. For this purpose, 29 groundwater samples were collected from the existing wells and were analyzed forvarious physicochemical parameters. The dominant cation was Na+, followed by Ca2+, Mg2+, and K+. The dominant anion was HCO3-, followed by Cl-, SO42-, and F-. The Gibbs plotshows thatrock-water interactions are the dominant factor controlling the groundwater chemistry. By using the GWQI, the quality of groundwater samples was 31% excellent, 21% good, 31% poor, and 17% very poor. The fluoride concentration in groundwater ranges from 0.2 to 5.60mg/L (mean, 2.10mg/L). 59% (i.e., 17 wells) of the groundwater samples were not suitable for drinking, because they surpassed the drinking water quality limit of 1.5mg/L. The remaining 41% (i.e., 12 wells) of the samples were suitable for drinking. The FPI indicates that 51.72% of the wells were highly polluted by fluoride. The noncarcinogenic health risk varies from 0.75 to 8.44 for children (83%), 0.34-3.84 for women (62%), and 0.27-3.01 for men (52%), which indicates that children are at higher health risk than women and men due to the physiological condition and the rates of ingestion.

Microwave assisted accelerated fluoride adsorption by porous nanohydroxyapatite

Fluoride pollution of water is a matter of concern in many countries due to its association with chronic kidney failure. Therefore, it is important to develop fast and efficient methods for fluoride removal from drinking water using environmentally friendly materials. In this article, the synthesis, characterization and microwave assisted accelerated fluoride removal by porous nanohydroxyapatite (PHAP) are reported. The PHAP samples were synthesized using polyvinyl pyrrolidone and sodium dodecyl sulphate micellar system as the template. The prepared nanohydroxyapatite was characterized using TEM, SEM, FT-IR, TGA, XRD and BET. Investigation of the morphology of microcrystals using TEM showed the presence of spherical particles of 20–35 nm size and highly porous rod-shaped crystals with the aspect ratio of 2:13. The adsorption of F− ions using PHAP was carried out under the influence of microwave radiations using concentrations comparable to existing F− levels in natural water. The equilibrium is reached within 80 s and this is the fastest saturation time recorded for any existing material. The kinetic experiments showed that the fluoride adsorption is an activated second order process. The equilibrium fluoride adsorption capacity of PHAP was found to be 9.19 mg g−1 at pH 6.5 for 80 s and this was proven to be a potential material to remove F− ions rapidly from drinking water.

Distribution of fluoride in surface water and a health risk assessment in the upper reaches of the Yongding River

The excessive exposure to high concentrations of fluoride in drinking water can lead to a serious disease called fluorosis. The upstream region of the Yongding River is an ecological protection area for Beijing. Some studies have reported that there is a high concentration of fluoride in the groundwater in this area. However, there are few data on the distribution of fluoride in surface water and health risk assessments in this area. In this study, the fluoride concentrations were determined by using the spectrophotometric method using data from 2013 to 2017 from 9 surface water quality monitoring stations in the upper reaches of the Yongding River. The health risks of fluoride were assessed using the approach developed by the United States Environmental Protection Agency (US EPA). The results indicated that the fluoride content in the drinking water ranged from 0.30 to 1.50 mg L-1, with an average of 0.86 mg L-1. In total, 22.7% of the analyzed samples exceeded the Chinese limit of 1.0 mg L-1 for fluoride, and 5.5% of samples had less than the permissible limit of 0.5 mg L-1. Higher fluoride concentrations and fluorosis hotspots were found to be predominately located downstream of the Yanghe River close to the Guanting Reservoir, where 71.4% of samples exceeded the limit of 1.0 mg/L-1. The spatial distribution of high fluoride concentrations was found to be primarily determined by industry. The hazard quotient (HQ) index for children, teenagers and adults indicated that 19.6%, 15.6%, and 5.1% of the samples in the upper reaches of the Yongding River, respectively, posed health hazards to the associated groups. Furthermore, the HQ index more than 1 for children, teenagers and adults had values of 64.3%, 56.1%, and 19.4%, respectively, in samples from the downstream region of the Yanghe River. Therefore, there are potential risks of dental and skeletal fluorosis in the upper river reaches of the Yongding River. It is imperative to take measures to reduce the fluoride pollution in surface water and control fluorosis. Action should be taken to improve the disposal of industrial waste.

Hydrogeochemical signatures and suitability assessment of groundwater with elevated fluoride in unconfined aquifers Badin district, Sindh, Pakistan

The fluoride pollution in the groundwater is a significant human health risk around the world. However, many diseases including dental, crippling and skeletal fluorosis cause due to high fluoride contamination in the drinking water. The objectives of this study were to investigate the occurrence of higher F− in the groundwater, geochemical composition, water type mechanism for minerals enrichment and groundwater quality for drinking and irrigation purposes. Therefore, fifty-seven groundwater samples were collected for the appraisal. The mean concentrations of physical parameters like depth, Temperature, electrical conductivity, total dissolved solid, power of hydrogen ion (pH) and turbidity were observed as 28 m, 19.78 °C, 2283 uS/cm, 1456 mg/L, 7.4 and 21.80 NTU respectively. Whereas, the mean concentrations of chemical parameters such as cations (Ca+2, Mg+2, Na+ and K+) were observed to be (92.12, 83.63, 251 and 12.40) mg/L and anions (Cl−, SO42−, HCO3−, NO3− and F−) were (375, 300, 285, 4.9 and 1.9) mg/L respectively. While the mean concentration of total Fe in the drinking water samples of study are were reported as 0.28 mg/L respectively. The range concentration of F− were 0.23–6.8 mg/L shows that 47% of drinking water samples exceeded the WHO limit (1.5 mg/L). The piper plot resulted in the dominance of (NaCl), and Gibbs plot represents rock and precipitation dominance ratios; while SAR and Sodium percentage (Na %) validates the salinity and sodium risk to the use of groundwater for irrigation purposes. Saturation indices expressed; the saturation of the fluorite mineral found within the range of (− 2.3 to 1.24). PCA results reveals four significant factors with total percentage contribution were 70.73%. Whereas, the water quality index resulted with mean and standard deviation as (2502.62 ± 2164). The overall quality of the groundwater is unfit for human consumption and irrigation purposes to the local population of the study area.

Fluoride removal efficiencies and mechanism of schwertmannite from KMnO4/MnO2–Fe(II) processes

Fluoride has an adverse effect on both the environment and industrial production. In particular, wastewater from smelting systems containing high concentrations of fluoride is a major cause of fluoride pollution. Based on the characteristics of such wastewater, a targeted and integrated method for removal fluoride using schwertmannite is proposed. The schwertmannite, prepared from the oxidation of Fe(II) by KMnO4 (Ksw) and MnO2(Msw), effectively removed fluoride within 30 min under certain conditions. Under most experimental conditions, the removal efficiency of F ion by Ksw was always 13 % higher than that by Msw, which is attributed to the different concentrations of OH− and SO42− for ion exchange. The calculations showed that the chemical formulas of Ksw and Msw are Fe8O8(OH)5.42±0.04(SO4)1.29±0.02 and Fe8O8(OH)5.28±0.04(SO4)1.36±0.02, respectively. In the Ksw system, 0.70 mol of OH− and 0.30 mol of SO42− were released per mole of F ions sorbed; those released for the Msw system were 0.69 mol and 0.31, respectively. The results showed that OH− played a primary role in the ion exchange and the schwertmannite showed good practicability for actual industrial wastewater.

The Methodology Development for Improving Energy Utilization and Reducing Fluoride Pollution of the Electroslag Remelting Process: A Review

Traditional electroslag remelting (ESR) technology using the slag with a high CaF2 content is faced with a high specific power consumption and fluoride pollution. Under double pressure, it is therefore very important to have a good understanding of the ESR process. The energy utilization, η, of the ESR depends on both the electrical, ηE, and thermal efficiency, ηH. Tailoring slag composition is one of the useful techniques to enhance energy utilization, because slag is very important to generate Joule heat for melting electrodes, control horizontal heat transfer, and maintain uniform distribution of alloy elements from the bottom to top of the remelted ingots in the ESR process. Therefore, herein, the aim is to review the effects of slag composition, especially CaF2 content, and temperature on the electrical conductivity and thermal conductivity, which further influence the heat balance during the ESR process. The volatilization mechanism of the liquid fluoride‐containing slag at an elevated temperature is introduced from the perspective of thermodynamics and kinetics. Meanwhile, some of the recent advances and technology improvements in energy utilization and productivity enhancements for the ESR process are summarized, which provide benefits to achieve sustainable development for the ESR process.

Spondias mombin, a potential bioindicator of potassium fluoride pollution

Ecological contamination by air pollutants is a worldwide problem. Fluoride-based compounds are released in large proportions into the atmosphere, soil and water from various industrial sources. These compounds are more phytotoxic to various plants than are other pollutants. The objective of this work was to determine the effects of fluoride in the form of potassium fluoride (KF)-simulated rain, on morphological and physiological responses, macronutrient content and fluoride accumulation in Spondias mombin leaves. S. mombin seedlings were transplanted to 5-liter pots containing Bioplant® substrate in a greenhouse. After acclimatization, the plants were subjected to KF, through simulated rain, at concentrations of 0, 10, 20 and 30 mg L−1, for a period of 9 days. Subsequently, visual and anatomical evaluations, chlorophyll a fluorescence variables, gas exchange, fluoride accumulation and macronutrient content were performed in all plants. KF-treated S. mombin developed necrosis on leaf surfaces with damage of up to 70%, followed by parenchymal tissue alterations characterized by cellular collapse and accumulation of phenolic compounds. We observed photochemical and macronutrient content changes that may compromise development of these plants. The correlation between the analyses suggested that noninvasive characteristics are important tools for detecting environmental pollution, and that S. mombin is an important bioindicator of KF-contaminated environments.

Thyroid gland pathology in children population exposed to the combination of iodine deficiency and fluoride pollution of environment

The article presents results of study of the impact of iodine deficiency and technogenic fluoride on the state of the thyroid gland in children. On the example of two districts of the city of Bratsk there were executed dynamic investigations (2002 and 2012), including the estimation of the pollution of ambient air and soil by fluorine compounds, levels of iodine intake by the body, the clinical examination of children aged from 5 to 7 years d and interviewing of their parents. In the course of the medical examination there were executed: physical examination by the pediatrician, endocrinologist, ultrasound examination of the thyroid gland, the determination both of serum hormone content by radioimmunoassay and urinary excretion offluorine and iodine. Concentrations of hydrogen fluoride and a solidfluorides in ambient air led to the accumulation offluoride ion in the soil. The iodine entering with drinking water and food, was established to provide only 37.5-50% of the daily requirement of iodine. Increased fluoride ion content in urine and milk teeth in children is associated with the concentrations of the fluorine-containing pollutants in the ambient air and soil. The fluoride pollution against the background of the natural iodine deficiency was established to increase the frequency of functional and morphological disorders of the thyroid gland in children.

Needle-like Mg-La bimetal oxide nanocomposites derived from periclase and lanthanum for cost-effective phosphate and fluoride removal: Characterization, performance and mechanism

Phosphate and fluoride are primary culprits of water eutrophication and skeleton fluorosis, respectively, severely threatening the security of aquatic lives and public health. To deal with the aqueous phosphate and fluoride pollution, PC@La nanocomposites were tailor-designed based on low-cost periclase and lanthanum salt via a facile urea hydrothermal method. Results from SEM, XRD, FTIR, XPS analysis revealed the PC@La-1.0 was constructed by Mg-La bimetal carbonated hydroxides with the three-dimensional needle-like nanostructure. Highly effective adsorption capacities for both phosphate (107.34 mg/g) and fluoride (63.11 mg/g) were achieved by PC@La-1.0. The adsorption was pH-dependent, and the optimal pH values for adsorption was 4.0–6.0. Over 80% of initial adsorption capacities remained after four adsorption–desorption cycles, indicating its satisfactory reusability. Superior adsorption selectivity for phosphate and fluoride was proven when co-existing with common ions and organics in solutions and real sewage. Mechanism analysis revealed that the unique structure of Mg-La bimetal carbonate hydroxide structure of PC@La-1.0 promoted an accumulative anion adsorption performance. Mg and La cations on PC@La-1.0 formed strong inner-sphere complexation with target phosphate and fluoride while the internal carbonate and hydroxyl groups contributed to adsorption via ion exchange. This study highlights the novel low-cost method to prepare promising candidates for efficient dephosphorization and defluorination from water.