Bioaccumulation of Fluoride in Plants and Its Microbially Assisted Remediation: A Review of Biological Processes and Technological Performance

Fluoride is widely found in soil–water systems due to anthropogenic and geogenic activities that affect millions worldwide. Fluoride ingestion results in chronic and acute toxicity, including skeletal and dental fluorosis, neurological damage, and bone softening in humans. Therefore, this review paper summarizes biological processes for fluoride remediation, i.e., bioaccumulation in plants and microbially assisted systems. Bioremediation approaches for fluoride removal have recently gained prominence in removing fluoride ions. Plants are vulnerable to fluoride accumulation in soil, and their growth and development can be negatively affected, even with low fluoride content in the soil. The microbial bioremediation processes involve bioaccumulation, biotransformation, and biosorption. Bacterial, fungal, and algal biomass are ecologically efficient bioremediators. Most bioremediation techniques are laboratory-scale based on contaminated solutions; however, treatment of fluoride-contaminated wastewater at an industrial scale is yet to be investigated. Therefore, this review recommends the practical applicability and sustainability of microbial bioremediation of fluoride in different environments.

Assessment of Fluoride Content in Ground Water and its Impact on Wheat and Vegetables of Dausa District, Rajasthan, India

In the present investigation samples of ground water ( open well, hand pump), wheat and vegetables (spinach, potato and tomato) were collected from different areas of Dausa district of Rajasthan and analyzed to access the adverse effect on human health due to fluoride accumulation. The fluoride concentration varies between 5.1-14.9 mg/l in the collected water samples, where as in wheat samples it was found in the range of 3.42-14.25mg/l and in vegetables from 1.19-22.45mg/l. The fluoride accumulation was found to be much higher in leafy vegetable (spinach) than that of in other vegetables, where seeds or tubers are the main edible part (potato and tomato). Cereal crop ( wheat ) also estimated with more fluoride content then potato and tomato. The maximum concentration of fluoride in water, wheat and vegetables was 14.9mg/l (Bairwa Mohalla/Dausa ), 14.25 µg/g (Seengpura/Dausa) and 22.45 µg/g (Kalyanpura/ Dausa) respectively. It was observed that large number of people from Bairwa Mohalla/Dausa were suffering from Skeletal and Dental fluorosis.

Tendürek Sönmüş Yanardağının Florotoksik Kaynak Suları Örneğinde Doğal Florozisin Çiftlik Hayvanı Kemiklerinin Flor Düzeyleri Üzerine Etkisi

It is known that the level of Fluoride in the spring waters from some volcanic lands is high and these waters cause Fluoride toxicity. Scientific studies have shown that in Doğubayazıt there is high amount of fluoride in some spring waters originating from the foothills of Tendürek volcano and normal level in Iğdır and Cappadocia volcanic lands. In this study, it was revealed comparatively how the spring waters in these regions affect the bone Fluoride levels of farm animals that are given as drinking water. Fluoride analyses in bone, water and urine samples were performed by means of an ion meter equipped with an iron selective electrode (ISE). The urine and bone fluoride levels of farm animals followed a similar course to water samples. Fluoride levels in bone and urine samples of Doğubayazıt were detected to be significantly higher in compared to Igdır and Cappadocia regions. Bone Fluoride analysis results were also supported by external bone and dental examination findings. The presence of a strong relationship between the analysed water, urine and bone Fluoride levels was determined in this study. It was found that drinking water has a very strong effect on urine and bone in terms of fluoride level. Consequently, Fluorine levels in the bones of farm animals drinking water with high Fluorine levels originating from Tendürek Mountain in Doğubayazıt were found to be higher than normal. Fluoride levels in the bones of farm animals that drank high-fluoride waters originating from Tendurek mountain in Doğubayazıt were found to be higher than normal. This situation can be evaluated as evidence that natural Fluoride toxicity formed by drinking water causes Fluoride accumulation on bones.

Bioindicator potential of Ricinus communis to simulated rainfall containing potassium fluoride

Background Fluoride pollution is a global problem because of its high phytotoxicity. Fluoride is released in air, water and soil through industrial processes, where it damages various plant species. Ricinus communis is widely distributed in Brazil, India and China and has been extensively used as a phytoremediation species in heavy metal-contaminated soils. However, few studies regarding the effect of air pollutants on R. communis have been published, and no information about the exposure of this species to fluoride is available. Therefore, the aim of the present study was to investigate the effects of fluoride on R. communis morphoanatomical and physiological responses using simulated rainfall containing potassium fluoride (KF). Methods Young plants at approximately 10 days after emergence were treated daily with KF using simulated rainfall at 0, 1.5, 3.0 and 4.5 mg L−1, for 37 consecutive days. Chlorophyll a fluorescence, gas exchange, anatomical characteristics and fluoride accumulation in the roots and leaves were evaluated after this period. Results No visual or anatomical symptoms were observed for the first three treatments. Necrosis and chlorosis were visually evident after the 37th day of KF application at 4.5 mg L−1, followed by changes in parenchyma tissues, cell collapse and phenolic compound accumulation at the end of the experiment. No damage was observed in terms of photosynthetic photochemical and biochemical stages. Maintenance of physiological characteristics in the presence of fluoride accumulation in roots and leaves were shown to be important fluoride biomarkers. These characteristics suggest that R. communis is tolerant to 1.5 and 3.0 mg L−1 KF, and is anatomically sensitive at 4.5 mg L−1 KF.

USE HERBAL PLANTS (CHAMAENERION ANGUSTIFOLIUM AND TANACETUM VULGARE) FOR MONITORING OF TERRITORIES POLLUTED BY FLUORINE-CONTAINING EMISSIONS

Specific features of fluoride accumulation by two species of herbaceous plants – Chamerion angustifolium (L.) Holub and Tanacetum vulgare L., were found at different distances from the aluminum smelter located in the Baikal region. The highest fluorine content was recorded at the distance of 3 km from the smelter: 433 mg / kg of dry weight in C. angustifolium, 306 mg / kg in T. vulgare. According to the level of accumulation of fluorine, the organs of C. angustifolium were arranged in the following order (as the concentration decreases): leaves> roots> stems ≥ flowers, for T. vulgare the another sequence was typical: roots> leaves> flowers ≥ stems. Calculation of the root barrier coefficient for different organs of C. angustifolium and T. vulgare indicates the existence of barrier mechanisms that prevent the entry of fluorine from the soil into the aerial part of plants. A feature of the accumulation of fluoride in the leaves of C. angustifolium is its active foliar absorption and barrier-free intake from the soil. It has been established that the rate of fluoride accumulation by the reproductive organs of both species is much lower than by the assimilation organs. The data obtained make it possible to recommend using C. angustifolium for monitoring air fluorine pollution, and T. vulgare – for soil fluorine pollution.