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22 Br/Cl versus I/Cl for serpentinites: a linear scale and b log-log scale. The trend of sedimentary marine pore waters (3), gas hydrate, MORB, and the compositions on amphibole and mica are shown for reference. Serpentinite data from Kendrick et al. (2011b, 2013b); MORB field from Kendrick et al. (2013a, 2017); mica/amphibole data from Kendrick (2012) and Kendrick et al. (2015b), see 15 

22 Br/Cl versus I/Cl for serpentinites: a linear scale and b log-log scale. The trend of sedimentary marine pore waters (3), gas hydrate, MORB, and the compositions on amphibole and mica are shown for reference. Serpentinite data from Kendrick et al. (2011b, 2013b); MORB field from Kendrick et al. (2013a, 2017); mica/amphibole data from Kendrick (2012) and Kendrick et al. (2015b), see 15 

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This chapter aims to provide a framework for understanding the distribution of halogens in the oceanic lithosphere. It reviews the concentrations of F, Cl, Br and I in seawater, marine sediment pore waters, hydrothermal vent fluids, fluid inclusions from deeper in the crust, and the complementary solid-phase reservoirs of organic matter and mineral...

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... Both iodine and selenium are released from underground locations into the atmosphere and seawater by volcanic activity and fissural fault emission [9,[20][21][22][23][24][25]. They also become available to the environment by decomposition of dead organisms [22,26]. ...
... The oceans are the largest reservoir and source of virtually all iodine on the land [26]. Iodine accumulated by algae is either emitted to the atmosphere as I2 gas or volatile iodocarbon compounds (CH3I) or buried in marine sediment which may contain 70% of the iodine present in the crust and seawater [21]. Molecular iodine and methyl iodide evaporate from the sea and rain down via atmospheric precipitation to flow back to the sea, where it is present as iodate (IO3 − ) and iodide (I − ), with some molecular iodine (I2) and iodinated organic compounds [20,26]. ...
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Iodide is an antioxidant, oxidant and thyroid hormone constituent. Selenoproteins are needed for triiodothyronine synthesis, its deactivation and iodine release. They also protect thyroidal and extrathyroidal tissues from hydrogen peroxide used in the ‘peroxidase partner system’. This system produces thyroid hormone and reactive iodine in exocrine glands to kill microbes. Exocrine glands recycle iodine and with high urinary clearance require constant dietary supply, unlike the thyroid. Disbalanced iodine-selenium explains relations between thyroid autoimmune disease (TAD) and cancer of thyroid and exocrine organs, notably stomach, breast, and prostate. Seafood is iodine unconstrained, but selenium constrained. Terrestrial food contains little iodine while selenium ranges from highly deficient to highly toxic. Iodine vs. TAD is U-shaped, but only low selenium relates to TAD. Oxidative stress from low selenium, and infection from disbalanced iodine-selenium, may generate cancer of thyroid and exocrine glands. Traditional Japanese diet resembles our ancient seashore-based diet and relates to aforementioned diseases. Adequate iodine might be in the milligram range but is toxic at low selenium. Optimal selenoprotein-P at 105 µg selenium/day agrees with Japanese intakes. Selenium upper limit may remain at 300–400 µg/day. Seafood combines iodine, selenium and other critical nutrients. It brings us back to the seashore diet that made us what we currently still are.
... Halogen signatures are among the best tracers of fluid source signatures. They are imprinted on crustal fluids by reservoirs or fractionation processes such as evaporation, evaporite dissolution, or organic-matter interaction and can be retained over geological time scales and long flow paths due to the limited extent of halogen fractionation in fluid-rock interaction (Kendrick, 2018). However, due to the small volumes of fluid inclusions, low concentrations of Br and I, and lack of reference materials, halogen analysis in fluid inclusions is challenging and only recently became possible (Fusswinkel et al., 2018). ...
... Sediments contain organic matter, which has high Br, and especially I, because these halo-gens are used in metabolic functions and thus become enriched in organic matter (Kendrick, 2018). Organic-matter halogen signatures are considered to remain unchanged during metamorphism, and metamorphic fluids formed by devolatilization reactions in metasedimentary rocks inherit them from their source rocks (Fu et al., 2012). ...
... 1A and 1B; Table 2; Kendrick and Burnard, 2013, and references therein). I and Br are essential to metabolic reactions in lifeforms, but biological I uptake far exceeds that of Br, leading to high Br/I ratios in modern-day seawater (Kendrick, 2018) and simultaneously very low Br/I ratios in marine biomass (Leblanc et al., 2006;Küpper and Carrano, 2019; Table 1). Interaction of buried biomass with marine pore fluids then leads to the development of the tight compositional array of pore-fluid halogen signatures (Fig. 1A), which approach the Br/I ratios in marine biomass, depending on the extent of organic-matter interaction controlled by the relative proportions of fluid to sediment and/or organic matter ( Fig. 1A; Elderfield, 1987a, 1987b;Muramatsu et al., 2007). ...
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Halogens (Cl, Br, I) are exceptional provenance tracers in crustal fluids because their ratios are not strongly altered during most fluid-rock interaction processes. The halogen systematics of metamorphic fluids are of particular interest because such fluids are key drivers of crustal-scale element fluxes and ore formation in orogenic belts, but they remain poorly studied due to analytical challenges. We present novel triple-halogen laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) fluid-inclusion data from metamorphic systems ranging in age from Archean to Phanerozoic. Our results show that the halogen signatures in Phanerozoic metamorphic fluids are controlled by variable degrees of organic-matter interaction in their source rocks, leading to increased I/Cl and decreased Br/I ratios relative to seawater. By contrast, Archean metamorphic fluids from organic matter–rich source rocks have low I/Cl and very high Br/I ratios, distinctly different from any known fluid source signature. We propose that these signatures nevertheless are consistent with organic-matter interaction because dominantly prokaryotic Archean lifeforms did not yet produce iodine-bearing metabolites. This prevented biosequestration and accumulation of iodine-rich organic matter in sediments and imposed halogen signatures onto Archean metamorphic fluids entirely unlike those in younger fluids.
... L'échange X -= OHpeut également être invoqué dans les minéraux nominalement anhydres où OH peut être présent en tant que défaut ponctuel. D'autres mécanismes de substitution ont été décrits pour les minéraux non hydroxylés, comprenant 2F -= CO3 2dans les carbonates (Kendrick, 2018b), ou encore des échanges plus complexes tels que les substitutions couplées (Mg, Fe) 2+ + F -= Al 3+ + O 2- (Armbruster et al., 2006). Des mécanismes d'incorporation hétérovalents ont pu être proposés pour expliquer l'incorporation d'halogènes au sein de minéraux anhydres, comme la substitution Al 3+ + F -= Si 4+ + O 2dans les pyroxènes (Pagé et al., 2016), ou (BO3F) 4-= SiO4 4dans les borates (Mi et Pan, 2018). ...
... Debret et al. (2016) a par exemple mesuré environ 40-50 ppm de F et 65-70 ppm de Cl dans des lawsonites d'un métagabbro des Schistes Lustrés, Alpes occidentales).L'incorporation des halogènes pourrait alors être modélisée dans les différents sites OH de ce minéral.En parallèle, des mécanismes de substitution couplés potentiels peuvent être testés dans les minéraux nominalement anhydres. Certains de ces mécanismes ont été présentés dans le chapitre 2 de la thèse (e.g.Armbruster et al., 2006 ;Pagé et al., 2016 ;Kendrick, 2018b).Plusieurs études sur assemblages naturels ou minéraux synthétiques ont pu montrer l'importance non négligeable de ces minéraux dans le transport des halogènes en traces jusque dans la zone de transition (voirRoberge et al. (2017) pour le stockage de F dans la wadsleyite et la ringwoodite, polymorphes de haute pression de l'olivine). La comparaison des coûts énergétiques pour un même mécanisme de substitution dans des minéraux tels que le grenat, le pyroxène ou l'olivine permettrait de déterminer des coefficients de partage pour les halogènes et de déterminer dans quelle(s) phase(s) anhydre(s) ces derniers sont plus favorablement incorporés.Il n'existe par ailleurs pratiquement aucune donnée sur le partage de l'iode en traces dans ces minéraux. ...
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La distribution des halogènes dans les silicates hydroxylés des zones de subduction est quantifiée par une modélisation ab initio et de l’analyse in situ. La quantification du coût énergétique de l’échange halogène – OH par modélisation ab initio permet d’étudier l’impact de la cristallochimie sur le partage des halogènes. Les calculs sont menés dans de grandes mailles où les halogènes sont considérés en tant que défauts ponctuels, pour des concentrations mineures à traces. Les estimations venant de la modélisation des halogènes dans la brucite montrent que les défauts ponctuels de F doivent être séparés d’au moins de 9 Å pour reproduire ce comportement d’éléments en traces, cette valeur passant à au moins 10 Å dans le cas de Cl et Br. Les résultats montrent une compétition entre interactions électrostatiques et effets stériques pour le contrôle de l’incorporation des halogènes. Les interactions avec les alcalins, tout comme l’occupation des sites octaédriques, jouent un rôle majeur en particulier dans les micas et les amphiboles. Le calcul de coefficients de partage met en avant un fractionnement entre halogènes, et montre que la pargasite, la biotite et la lizardite sont favorisées par les trois halogènes, suivies par le clinochlore, la trémolite et la carpholite. Les phyllosilicates dioctaédriques et l’épidote sont en revanche défavorisés. Le LA-ICP-MS/MS a été utilisé afin de quantifier in situ les halogènes en tant qu’éléments en traces dans les silicates hydroxylés. Un protocole est proposé pour la mesure de 35Cl, 79Br, 81Br et 127I, permettant de réduire et/ou d’enlever les interférences isobariques. Des limites de détection d’environ 20 ppm sont atteintes pour Cl et 1 ppm pour Br. En combinant LA-ICP-MS/MS et microsonde électronique, F, Cl et Br ont été quantifiés dans des assemblages minéralogiques de roches métamorphiques et mantelliques refertilisées du complexe ophiolitique du Mont Albert (Québec, Canada), ainsi que d’autres éléments en traces et majeurs. La présence d’amphibole contenant des halogènes dans le coin mantellique démontre sa refertilisation par des fluides enrichis en Cl, Br provenant de roches métamorphiques du panneau plongeant. Les données permettent de distinguer au moins trois étapes d’interactions entre ces fluides et le manteau pendant la formation de l’ophiolite, avec une diminution progressive en Cl, Hf et Zr dans les amphiboles des péridotites, et des variations des teneurs en autres éléments en traces. F est majoritairement stocké dans le panneau plongeant, tandis que Cl et Br sont également abondamment trouvés dans le manteau refertilisé.
... Rest of the water quantity is contaminated by various human-source pollutants such as agricultural activities, municipal wastewater, and industrial wastes [5,6]. The major water pollutants can be specified as toxic heavy metals, pesticides, dyes, organic acids, halogenated compounds, fertilizers, and microorganisms [7][8][9][10]. Because of non-biodegradability and toxicity, among these pollutants, heavy metals are the most hazardous materials for ecosystem and organism, because these toxic and dangerous metals tend to accumulate in ecosystem especially the food chain and the living organism. ...
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... Fluorine and chlorine are of great interest in geological and environmental studies due to their special, highly mobile and volatile properties [1,2]. Fluorine is a minor constituent in a wide range of sedimentary minerals including phosphorites, phosphates, carbonates, silicates and clay minerals [3][4][5][6]. Chlorine is the dominant ligand that enables metal transport in the majority of hydrothermal solutions [6][7][8]. Thus, the content of fluorine, chlorine and ratios of element/Cl in sediment can be used as tracers for chemical evolution of fluids and water/rock interactions in low temperature sediment alteration [9,10] and high temperature hydrothermal systems [11][12][13][14], element recycling during subduction-related sediment melting [4,15], and early diagenesis of sediment [3]. ...
... Fluorine is a minor constituent in a wide range of sedimentary minerals including phosphorites, phosphates, carbonates, silicates and clay minerals [3][4][5][6]. Chlorine is the dominant ligand that enables metal transport in the majority of hydrothermal solutions [6][7][8]. Thus, the content of fluorine, chlorine and ratios of element/Cl in sediment can be used as tracers for chemical evolution of fluids and water/rock interactions in low temperature sediment alteration [9,10] and high temperature hydrothermal systems [11][12][13][14], element recycling during subduction-related sediment melting [4,15], and early diagenesis of sediment [3]. Therefore, recent studies have focused on the precise determination of fluorine and chlorine in sediment. ...
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Fluorine and chlorine are important tracers for geochemical and environmental studies. In this study, a rapid alkaline digestion (NaOH) method for the simultaneous determination of fluorine and chlorine in marine and stream sediment reference samples using ion chromatography is developed. The proposed method suppresses the volatilization loss of fluorine and chlorine and decreases the matrix effects. The results are in good agreement with fluorine ~100%, chlorine ranging from 90 to 95% of the expected concentrations. The detection limits of this method were 0.05 μg/g for fluorine and 0.10 μg/g for chlorine. This method is simple, economical, precise and accurate, which shows great potential for the rapid simultaneous determination of fluorine and chlorine in large batches of geological and environmental samples commonly analyzed for environmental geochemistry studies.
... At low pressures and high temperatures, the hydrothermal fluids produced during heating of evaporites will comprise a coexisting brine and vapor (Liebscher et al., 2006;Coumou et al., 2009;. It is not well understood whether fractionation of Br and Cl occurs during the phase separation stage (Kendrick, 2018). Data from conjugate vapor and brine fluids from hydrothermal vents, for example, have similar Br/Cl ratios (Von Damm et al., 1997;Wu et al., 2012) which is consistent with experimental data (Berndt and Seyfried, 1997). ...
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Volatile emissions to the atmosphere associated with the Siberian Traps eruptions at the Permian-Triassic boundary were sourced from the outgassing of primary magmas and the sedimentary host rocks into which they were intruded. Halogens in volcanic gases may have played an important role in environmental degradation and in stratospheric ozone destruction. Here we investigate how halogens behave during the interaction between salts and basalt magma emplaced as sills and erupted as lava. We present whole-rock, trace, and halogen concentrations for a suite of samples from three locations in the Siberian Traps Large Igneous Province, including basalt lavas erupted, and dolerites intruded into both organic-bearing shales and evaporites. Dolerites are enriched in Cl, Br, and I; their enrichment in Cl is similar to MORB and OIB that have been inferred to have assimilated seawater. The dolerites exhibit halogen compositional systematics, which extend towards both evaporites and crustal brines. Furthermore, all analyzed samples show enrichment in Rb/Nb; with the dolerites also showing enrichment in Cl/K similar to MORB and OIB that have been inferred to have assimilated seawater. We infer that samples from all three locations have assimilated fluids derived from evaporites, which are components of crustal sedimentary rocks. We show that up to 89% of the chlorine in the dolerites may have been assimilated as a consequence of the contact metamorphism of evaporites. We show, by thermal modeling, that halogen transfer may occur via assimilation of a brine phase derived from heating evaporites. Halogen assimilation from subcropping evaporites may be pervasive in the Siberian Traps Large Igneous Province and is expected to have enhanced emissions of Cl and Br into the atmosphere from both intrusive and extrusive magmatism.
... Fluorine concentrations in biogenic aragonites vary between 500 to 1600 ppm (Ramos et al., 2005;Tanaka and Ohde, 2010;Tanaka et al., 2013), making it one of the most abundant impurities in this carbonate mineral phase. Biogenic low-magnesium calcites typically contain 75 to 600 ppm fluorine (Opdyke et al., 1993;Rosenthal and Boyle, 1993), and the fluorine content of biogenic calcites increases as a function of the magnesium content of the calcite (Ohde and Kitano, 1980;Kendrick, 2018). ...
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The abundant occurrence of calcium carbonate minerals in marine sediments and their high fluorine content suggests that fluorine is a good candidate for reconstructing paleoceanographic parameters. However, the potential of fluorine as a paleoproxy had hardly been explored, and fundamental insights into the behaviour of fluorine in biogenic carbonates and marine sediments is required. A first-principles modelling approach is used here to analyse the incorporation mechanisms of fluorine into crystalline calcium carbonates. We compute F incorporation into the CaCO3 lattice via a number of mechanisms, but concentrate on comparison of the energetics of the two easiest substitution mechanisms: replacing one oxygen atom within the carbonate group to form a (CO2F)⁻ group as against a substitution involving replacement of the CO3 group by two fluorine ions to form a CaF2 defect. These incorporation mechanisms are fundamentally different from that of iodine into calcium carbonates, where a carbon atom is replaced. Our simulations suggest that the substitution of CO32- by F22- is the most favoured and that fluorine is preferentially incorporated into the three naturally-occurring polymorphs of calcium carbonate in the order vaterite ⪆ aragonite ≫ calcite. These results explain the previously-reported preponderance of fluorine in aragonite corals, and lend support to the use of F/Ca as a proxy for ocean pCO2.
... The systematic depletion of 37 Cl in chlorides of all the pore fluids in comparison to seawater is intriguing as chlorides are unreactive which causes them to remain in solution with very little incorporation into minerals at low temperature. Clay minerals can store less than 100 ppm Cl (Kendrick, 2018), which is much lower than the pore fluids (%19,000 ppm Cl). Hence clays cannot compensate for the missing 37 Cl of pore fluid chloride without calling for unrealistic d 37 Cl values (!200‰) of chloride stored within clays. ...
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In order to examine the seawater-seafloor sediment interactions that influence the chemical composition of seawater through time, we examined hundreds of pore fluid geochemical analyses from 13 clay-rich sedimentary successions drilled by the ODP-IODP. Chemical trends such as monotonous increases in Ca²⁺, and decreases in Mg²⁺ and δ¹⁸O with depth are traditionally interpreted to result from water-rock interaction. In this view, the release of Ca²⁺ into fluids and the uptake of Mg²⁺ and ¹⁸O mainly results from the formation of low-temperature clays in the sediment and within underlying basalts. Chloride concentration profiles and isotopic compositions, however, suggest that different processes may influence pore water geochemistry. The data examined here show relatively constant chloride contents but with a systematic decrease in δ³⁷Cl of chlorides with depth from 0 permil (the seawater value) down to -8.5 permil. The δ³⁷Cl data are highly correlated with δ¹⁸O (with δ¹⁸O down to -5.7 permil). The δ³⁷Cl-depletions of pore fluid chlorides are found in all studied sedimentary piles regardless of tectonic or sedimentary history. These trends cannot be explained by water-rock exchange reactions because minerals formed at low temperature have Cl contents that are too low to compensate for δ³⁷Cl depletions observed in pore fluids. Accordingly, we hypothesize that fluid-specific processes are responsible for the δ³⁷Cl-depletions of the fluids and that δ³⁷Cl-enriched chlorides were expelled out of the sediments into the ocean. After reviewing the fluid-specific processes that are known to change the chlorine isotope ratios in chlorides, we rule out diffusion and gravitational isotope fractionations of chlorides could generate this isotope pattern. The flow of a δ³⁷Cl -depleted fluid from the underlying basaltic basement into the sediments could explain the δ³⁷Cl data. But the mechanism that produces depletion in δ³⁷Cl of the fluid remains unknown. It cannot be chloride exchanges between fluids and rocks. Here we show that compaction-induced ion filtration of chlorides through clay-rich membranes can produce the observed pore fluid δ³⁷Cl-depletions, with isotope fractionation factors ranging from 1.000 to 1.008 between the chlorides of the expelled fluid (the permeate) and those of the residual fluid (the retentate). We find that smectite-rich sediments are associated with higher isotopic fractionation factors, while illite/chlorite-rich sediments are associated with intermediate values and with clay-poor sediments associated with lower values. This suggests that chlorine isotope fractionation might be controlled by surface charge associated with specific clay minerals. Our calculations show that compaction-induced filtration has the capacity to produce ¹⁸O-depletion for oxygen isotope fractionation factors between the expelled fluid and the retentate ranging from 1.000 to 1.005. ¹⁸O-enrichment in the expelled fluid is in agreement with the experimental data of Haydon and Graf (1986). Overall, although further experimental work on both chlorine and oxygen isotopes is certainly needed, the results of this study indicate that ion-filtration should be considered as a potential mechanism for fractionating isotopic species in sediment pore waters, particularly for oxygen isotope ratios whose variations are often commonly attributed to water-rock exchange.
... Distribution of halogens in arc lavas (Dalou et al., 2014 and references therein) suggests that arcs can be roughly grouped into "high-Cl" (F/Cl ratios < 1) and "low-Cl" (F/Cl ratios < 1) types (e.g., Fig. 5 in Dalou et al., 2014). Since seawater is nearly 15,000 times richer in Cl than F (Cl ave = 19,350 ppm, F ave = 1.3 ppm; Kendrick, 2018) and chlorine is highly soluble in slab-derived hydrous fluids (Brennan, 1993), the majority of melt inclusions and glasses in volcanic arcs have F/Cl ratios of 0.8 and lower (Dalou et al., 2014). This is consistent with estimated F/Cl ratio in slab-derived aqueous fluid of about 0.1-0.25 (Dalou et al., 2014). ...
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Plutonic associations in orogenic belts are potent indicators of multi-stage fractionation of primitive arc magmas and growth of island-arc crust under evolving redox conditions in ancient subduction zones. Ildeus-Lucha ultramafic–mafic complex (ILC) was emplaced at 232–233 Ma within the Mesozoic Stanovoy convergent margin and subsequently underwent multi-stage hydrothermal alteration and greenschist to amphibolite facies metamorphism (~140 Ma), followed by adakite and K-lamprophyre magmatism (114–117 Ma). Dunite, wehrlite, pyroxenite and gabbro in the ILC are composed of olivine, clinopyroxene, orthopyroxene, plagioclase and late-magmatic amphibole. Mineral compositions in the ILC are typical of island-arc plutonic complexes characterized by early crystallization of orthopyroxene, plagioclase intercumulus and presence of magmatic amphibole. Ultramafic-mafic rocks display high-field strength (HFS) element depletions coupled with large-ion lithophile (LIL) element enrichments, indicating formation via crystal fractionation of mafic primary magma derived from a subduction-related mantle source. Some ultramafic rocks from the ILC contain native metals (W, Pt, Au, Ag, Zn, Bi) and intermetallic compounds (Cu-Au-Ag, Pt-Rh-Pd, Cu-Sn-Zn, etc.) included in silicate minerals, or observed as discrete phases in the finer-grained silicate-oxide-sulfide matrix. Textural evidence and association with either primary (magmatic) or secondary (metasomatic or metamorphic) mineral phases, suggest either magmatic (high-temperature) or metasomatic (low-temperature) origin of metals and metallic compounds. The following models of their formation can be proposed on the basis of the presented data: a) crystallization (W and, possibly, Pt) from metal-rich arc magmas under unusually reduced conditions in subduction-related lithosphere; b) formation from magmatic sulfides during pervasive serpentinization and release of abiogenic hydrocarbons and c) precipitation from chlorine-rich, saline aqueous fluids associated with collision-related metasomatism of the Stanovoy island arc crust.
... A number of studies have estimated F fluxes associated with the diverse processes that occur during subduction of oceanic lithosphere (e.g., Barnes et al., 2018;John et al., 2011;Kendrick, 2018;Straub Q6 & Lane, 2003a, 2003b. Calculations of the F influx into the subduction zone are based on convergence rates and estimates of the F concentrations and thicknesses of the layers of the subducting lithosphere. ...
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This review provides a synthesis of what is currently known about the natural and anthropogenic fluxes of fluorine on Earth, offering context for an evaluation of the growing environmental impact of human-induced F mobilization and use. The largest flux of F at the Earth's surface derives from the mobilization of F during chemical (2.2 Tg F/yr (where 1 Tg = 10¹² g) and mechanical (7 Tg F/yr) weathering of rocks. Humans supplement these fluxes by mining fluorospar and apatite ores to make a variety of industrial chemicals and fertilizers, mobilizing 2.9 and 7.6 Tg F/yr, respectively. Other large anthropogenic fluxes derive from the manufacture of bricks (1.8 Tg F/yr) and extraction of groundwater (0.9 to 1.7 Tg F/yr). Rivers deliver ~3.6 Tg/yr of dissolved fluoride to the oceans, where the mean residence time of dissolved F in seawater is ~500,000 yr. F is removed from the oceans by the deposition of terrigenous (4.3 Tg F/yr) and authigenic sediments (1.24 Tg F/yr), and approximately 10 Tg F/yr is removed from the surface of the Earth by subduction of the oceanic lithosphere. Humans have increased the flux of F to the atmosphere and in rivers by more than a factor of 2, with the largest impacts stemming from the use of phosphorus fertilizers, the production of brick, and extraction of groundwater. Despite their well-documented toxicity, perfluoroalkyl substances make only a small contribution to F emitted to the atmosphere and natural waters.