What is the significance of high water in volcanic rocks

Although fluoride has no recognized essential function in human growth and development, it has a fundamental role in the prevention of caries tooth decay [ 25 , 26 ]. As a result, throughout the world many countries started programs of fluoridation of drinking water and the development of fluoride containing oral care products toothpastes and mouth rinses and supplements fluoride tablets , as public health protective measures against tooth decay. Fluorosis results of a high consumption of F that may cause chronic fluoride toxicity, being harmful and, sometimes, causing severe poisoning that in the absence of medical treatment, can be lethal.

One of the main mechanisms involved in the pathogenesis of fluorosis is an increased oxygen radical generation and lipid peroxidation. The most common pathology in fluoride endemic areas is dental fluorosis, which usually occurs in areas where fluoride exposure concentrations are above 1. Dental fluorosis has a progressive outcome [ 29 ]: in its initial stages, the teeth develop chalky white patches and become rough, and as time goes by, yellow to dark brown lines may also become visible [ 28 , 29 , 30 ] in the teeth.

The early symptoms are severe pain in the spine, joints, and hip area; on time, the muscles in the spine will become calcified, and crippling deformities of the spine and the major joints will occur [ 31 ]. Since the dental and skeletal fluorosis are irreversible pathologies, the only way to mitigate its effects is through prevention, by keeping fluoride intake within the safety limits defined by the WHO, such as a maximum that is below 1.

Several cases of endemic fluorosis due to high F concentrations in groundwater have been reported in volcanic areas worldwide, particularly in East Africa, India, and China, where millions of people are affected [ 32 ].

The association between volcanic activity and human fluorosis was first established in Kyushu Island, Southwest Japan. In an attempt to prevent excessive exposure to fluoride, the drinking water concentration standards and guidelines are targeted so that total fluoride intake from all sources does not exceed exposure guidance values [ 39 , 40 ].

Since fluoride occurs naturally in several sources, the exposure to this element is widespread, and therefore programs to quantify the exposure and its effects in human health are often necessary. In human biomonitoring, measurements of the internal dose are assessed in human biological fluids or tissues, thus integrating fluoride absorbed from all exposure routes [ 41 ]. The concentration of fluoride in urine is used as a biomarker of recent exposure [ 22 , 42 , 43 ], because urine is the main route of elimination of fluoride.

Although urinary fluoride concentrations do not provide a direct measure of fluoride due to variations in urine flow and pH, the studies of urinary fluoride levels are ideal for assessing the intake of fluoride in populations [ 45 ]. Nails have been used as biomarkers of acute, sub-chronic, and chronic exposure to fluoride [ 47 , 48 ] in humans, since in this matrix the fluoride concentration reflects the average level of intake and the plasma concentration over a protracted period, usually 1—2 weeks depending on how often the nails are clipped [ 49 ].

There are several studies about the occurrence of fluoride in the environment and its relationship to human health spanning a wide variety of disciplines that include the fields of medicine, dentistry, environmental and occupational health, toxicology, environmental geology, petrology, geochemistry, economic geology, hydrogeology, and soil science [ 52 ]. For more robust evidence of the relationship between fluoride and human health, studies regarding interdisciplinary approaches and combined methods to establish environmental exposures, health outcomes, and the relationships between them [ 53 ] are required, instead of the usual unidirectional approaches.

This multidisciplinary association allows the identification of natural and anthropogenic sources of harmful materials in the environment, the understanding of how people are exposed to such materials, and what can be done to minimize or prevent such exposure [ 56 ].

The effects in human health for excessive exposure to fluoride have been studied worldwide, and exposure guidance values have been established. However, nowadays in many regions of the world, fluorosis continues to be endemic.

Considering that volcanic aquifers can promote the occurrence of high F contents in groundwater [ 57 , 58 ], some studies have determined the health impacts of fluoride exposure in drinking water due to volcanic activity.

In Vanuatu the constant low-level basaltic volcanic activity results in a continuous release of fluoride gas, which is reflected in cow rib bones and teeth fluoride content in grazing animals.

According to Cronin and Sharp , the possible long-term accumulation of F in the grazing animals results from the consumption of plants F-bearing volcanic ash and drinking F-rich waters in some areas the fluoride concentration in water reached values up to 2.

Also, in New Zealand in the hydrothermal system of Ruapehu volcano, significant concentrations of soluble F in ashes are leached into the soils and water over longer periods, representing a long-term environmental hazard for the inhabitants of this area [ 19 ]. Despite the results evidencing the clear association between volcanic activity and fluoride availability, to act in the mitigation and prevention of fluoride exposure, it is necessary to better understand which are the main routes of exposure, since they can differ according to the region in study.

In this volcanic island, the groundwater geochemistry is influenced by the dissolution of primary minerals of the volcanic rocks [ 60 ] that are naturally enriched in fluoride. Also, the habit of tea consumption is well established in the local communities, because this is the only place in Europe where tea is produced, processed, and commercialized [ 61 ] since Until , there was no information regarding the health effects of chronic fluoride exposure in the inhabitants of this island; although in some studies the authors have identified anomalous values of fluoride in water [ 12 ] and clear signals of dental fluorosis in humans [ 14 ] and animals [ 62 ], none was focused on estimating the effects of the exposure to fluoride in humans.

In the study by Linhares et al. Considering that within the residents of this island, the tea consumption is a well-established habit in adults and children and that tea is a fluoride-bioconcentrating plant, another study was developed in by Linhares et al.

The authors concluded that the Azorean tea brands had higher fluoride content than other international brands. Many volcanoes sit over magma chambers. An eruption reduce s the pressure inside the magma chamber. Large eruptions can nearly empty the magma chamber.

The layers of magma may be document ed by the type of eruption material the volcano emits. Gases, ash, and light-colored rock are emitted first, from the least-dense, top layer of the magma chamber.

Dark, dense volcanic rock from the lower part of the magma chamber may be released later. In violent eruptions, the volume of magma shrinks so much that the entire magma chamber collapses and forms a caldera. All magma contains gases and a mixture of simple element s. Being that oxygen and silicon are the most abundant elements in magma, geologists define magma types in terms of their silica content, expressed as SiO 2. These differences in chemical composition are directly related to differences in gas content, temperature, and viscosity.

This type of magma has a low gas content and low viscosity, or resistance to flow. Mafic magma also has high mean temperatures, between o and o Celsius o and o Fahrenheit , which contributes to its lower viscosity.

Low viscosity means that mafic magma is the most fluid of magma types. This lava cools into basalt , a rock that is heavy and dark in color due to its higher iron and magnesium levels. The Hawaiian Islands are a direct result of mafic magma eruptions. This results in a higher gas content and viscosity. Its mean temperature ranges from o to o Celsius o to o Fahrenheit.

This more gaseous and sticky lava tends to explode violently and cools as andesite rock. Intermediate magma most commonly transforms into andesite due to the transfer of heat at convergent plate boundaries. Andesitic rocks are often found at continent al volcanic arcs, such as the Andes Mountains in South America, after which they are named.

As a result, felsic magma also has the highest gas content and viscosity, and lowest mean temperatures, between o and o Celsius o and o Fahrenheit. These trapped bubbles can cause explosive and destructive eruptions. These eruptions eject lava violently into the air, which cools into dacite and rhyolite rock.

Much like intermediate magma, felsic magma may be most commonly found at convergent plate boundaries where transfer of heat and flux melting create large stratovolcano es. Magma exists as pockets and plumes beneath the surface of the Earth.

Photograph by Carsten Peter, National Geographic. Mysterious Magma. Magma is usually studied as lava or igneous rock. In , the Icelandic Deep Drilling Project created a well that uses magma to generate geothermal energy.

Normally, geothermal energy is created by pumping water into hot volcanic bedrock, creating steam that is then harnessed to generate electricity. This huge increase in temperature allowed just one magma well to generate roughly 36 megawatts of electricity, powering 36, homes. In comparison, one single wind turbine generates between 1 to 3 megawatts. Also called a collision zone. Also called the average. Also known as a composite volcano. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.

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Stamatis, G. Stavrakis, P. Stone, A. Stumm ed. Voudouris, K. Download references. Sofias 12, , Xanthi, Greece. You can also search for this author in PubMed Google Scholar.

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Abstract This work is referred to the characterization of the environmental hydrochemistry in the broader Sapes area — Thrace region, on the basis of physico-chemical properties of surface and groundwaters occurring in the volcanosedimentary formations of this area, where gold mining activities are planned to operate. References Alexakis, D. Google Scholar Andrews, N. Google Scholar Appelo, C.

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Google Scholar Sideris, K. Google Scholar Voudouris, K. Sofias 12, , Xanthi, Greece C. Zaggana Authors C.