Misplaced Pages

#580419

64-466: As part of the Eastbourne Ancestors project, over 300 sets of human remains excavated from Anglo-Saxon cemeteries were re-examined. Heritage Officer Jo Seaman and his team found two boxes labelled "Beachy Head, something to do with 1956 or 1959". Inside they found a very well-preserved human skeleton. The Beachy Head Lady is the most complete skeleton in the collection. Radiocarbon dating suggested

128-538: A differ by more than 4. Phosphate can form many polymeric ions such as pyrophosphate , (P 2 O 7 ) , and triphosphate , (P 3 O 10 ) . The various metaphosphate ions (which are usually long linear polymers) have an empirical formula of (PO 3 ) and are found in many compounds. In biological systems , phosphorus can be found as free phosphate anions in solution ( inorganic phosphate ) or bound to organic molecules as various organophosphates . Inorganic phosphate

192-548: A standard . They express the proportion of an isotope that is in a sample. The values are expressed as: where X represents the isotope of interest (e.g., C ) and R represents the ratio of the isotope of interest and its natural form (e.g., C/ C). Higher (or less negative) delta values indicate increases in a sample's isotope of interest, relative to the standard , and lower (or more negative) values indicate decreases. The standard reference materials for carbon, nitrogen, and sulfur are Pee Dee Belamnite limestone, nitrogen gas in

256-467: A " peak phosphorus " would occur in 30 years and Dana Cordell from Institute for Sustainable Futures said that at "current rates, reserves will be depleted in the next 50 to 100 years". Reserves refer to the amount assumed recoverable at current market prices. In 2012 the USGS estimated world reserves at 71 billion tons, while 0.19 billion tons were mined globally in 2011. Phosphorus comprises 0.1% by mass of

320-623: A central phosphorus atom surrounded by four oxygen atoms in a tetrahedral arrangement. It is the conjugate base of the hydrogen phosphate ion H(PO 4 ) , which in turn is the conjugate base of the dihydrogen phosphate ion H 2 (PO 4 ) , which in turn is the conjugate base of orthophosphoric acid , H 3 PO 4 . Many phosphates are soluble in water at standard temperature and pressure . The sodium, potassium, rubidium , caesium , and ammonium phosphates are all water-soluble. Most other phosphates are only slightly soluble or are insoluble in water. As

384-545: A date range of 125 to 245 AD for the remains. Isotope analysis indicated that the Beachy Head Lady grew up in south-east England, and may have been born in the region. Initially, the skull shape led to an assessment that the woman had originated from Sub-Saharan Africa . This led some to claim erroneously that she had been the first known person of sub-Saharan origin in Britain . However, further DNA analysis established that

448-399: A function of location, and the geology that the water percolates through. Sr, Sr and oxygen isotope variations are different all over the world. These differences in isotopic ratio are then biologically 'set' in our hair as it grows and it has therefore become possible to identify recent geographic histories by the analysis of hair strands. For example, it could be possible to identify whether

512-473: A high phosphate-to-protein ratio, such as soft drinks, fast food, processed foods, condiments, and other products containing phosphate-salt additives is advised. Phosphates induce vascular calcification , and a high concentration of phosphates in blood was found to be a predictor of cardiovascular events . Phosphates are the naturally occurring form of the element phosphorus , found in many phosphate minerals . In mineralogy and geology, phosphate refers to

576-517: A means of characterization. Characterization of artifacts involves determining the isotopic composition of possible source materials such as metal ore bodies and comparing these data to the isotopic composition of analyzed artifacts. A wide range of archaeological materials such as metals, glass and lead-based pigments have been sourced using isotopic characterization. Particularly in the Bronze Age Mediterranean, lead isotope analysis has been

640-480: A number of different isotopic forms, of which two or more are stable. For example, most carbon is present as C, with approximately 1% being C. The ratio of the two isotopes may be altered by biological and geophysical processes, and these differences can be utilized in a number of ways by ecologists. The main elements used in isotope ecology are carbon, nitrogen, oxygen, hydrogen and sulfur, but also include silicon, iron, and strontium. Stable isotopes have become

704-494: A popular method for understanding aquatic ecosystems because they can help scientists in understanding source links and process information in marine food webs. These analyses can also be used to a certain degree in terrestrial systems. Certain isotopes can signify distinct primary producers forming the bases of food webs and trophic level positioning. The stable isotope compositions are expressed in terms of delta values (δ) in permil (‰), i.e. parts per thousand differences from

SECTION 10

#1733092753581

768-650: A record of the effects of the Milankovitch cycles on climate change during the Quaternary, revealing an approximately 100,000-year cyclicity in the Earth's climate . Phosphate In chemistry , a phosphate is an anion , salt , functional group or ester derived from a phosphoric acid . It most commonly means orthophosphate , a derivative of orthophosphoric acid, a.k.a. phosphoric acid H 3 PO 4 . The phosphate or orthophosphate ion [PO 4 ]

832-805: A rock or ore containing phosphate ions. Inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry. The largest global producer and exporter of phosphates is Morocco . Within North America, the largest deposits lie in the Bone Valley region of central Florida , the Soda Springs region of southeastern Idaho , and the coast of North Carolina . Smaller deposits are located in Montana , Tennessee , Georgia , and South Carolina . The small island nation of Nauru and its neighbor Banaba Island , which used to have massive phosphate deposits of

896-450: A rule, the hydrogen and dihydrogen phosphates are slightly more soluble than the corresponding phosphates. In water solution, orthophosphoric acid and its three derived anions coexist according to the dissociation and recombination equilibria below Values are at 25   °C and 0 ionic strength. The p K a values are the pH values where the concentration of each species is equal to that of its conjugate bases . At pH 1 or lower,

960-507: A terrorist suspect had recently been to a particular location from hair analysis. This hair analysis is a non-invasive method which is becoming very popular in cases that DNA or other traditional means are bringing no answers. Isotope analysis can be used by forensic investigators to determine whether two or more samples of explosives are of a common origin. Most high explosives contain carbon, hydrogen, nitrogen and oxygen atoms and thus comparing their relative abundances of isotopes can reveal

1024-443: A useful tool for determining the sources of metals and an important indicator of trade patterns. Interpretation of lead isotope data is, however, often contentious and faces numerous instrumental and methodological challenges. Problems such as the mixing and re-using of metals from different sources, limited reliable data and contamination of samples can be difficult problems in interpretation. All biologically active elements exist in

1088-400: Is incorporated into the body primarily through ingestion at which point it is used in the formation of, for archaeological purposes, bones and teeth . The oxygen is incorporated into the hydroxylcarbonic apatite of bone and tooth enamel . Bone is continually remodelled throughout the lifetime of an individual. Although the rate of turnover of isotopic oxygen in hydroxyapatite

1152-634: Is a 3.2‰ enrichment of N vs. diet between different trophic level species in ecosystems. In the Baltic sea, Hansson et al. (1997) found that when analyzing a variety of creatures (such as particulate organic matter (phytoplankton), zooplankton , mysids , sprat, smelt and herring,) there was an apparent fractionation of 2.4‰ between consumers and their apparent prey. In addition to trophic positioning of organisms, δ N values have become commonly used in distinguishing between land derived and natural sources of nutrients. As water travels from septic tanks to aquifers,

1216-484: Is an organophosphate , an ester of orthophosphoric acid of the form PO 4 RR′R″ where one or more hydrogen atoms are replaced by organic groups. An example is trimethyl phosphate , (CH 3 ) 3 PO 4 . The term also refers to the trivalent functional group OP(O-) 3 in such esters. Phosphates may contain sulfur in place of one or more oxygen atoms ( thiophosphates and organothiophosphates ). Orthophosphates are especially important among

1280-405: Is becoming a more and more popular method in attempting to monitor nutrient input into estuaries and coastal ecosystems. Environmental managers have become more and more concerned about measuring anthropogenic nutrient inputs into estuaries because excess in nutrients can lead to eutrophication and hypoxic events , eliminating organisms from an area entirely. Analysis of the ratio of O to O in

1344-440: Is common to perform analysis on at least two of the previously mentioned three isotopes for better understanding of marine trophic interactions and for stronger results. The ratio of H, also known as deuterium , to H has been studied in both plant and animal tissue. Hydrogen isotopes in plant tissue are correlated with local water values but vary based on fractionation during photosynthesis , transpiration, and other processes in

SECTION 20

#1733092753581

1408-405: Is derived from Bolivia and that from Colombia. Stable isotopic analysis has also been used for tracing the geographical origin of food, timber, and in tracing the sources and fates of nitrates in the environment. In isotope hydrology , stable isotopes of water ( H and O) are used to estimate the source, age, and flow paths of water flowing through ecosystems. The main effects that change

1472-439: Is derived from phosphoric acid by the removal of three protons H . Removal of one proton gives the dihydrogen phosphate ion [H 2 PO 4 ] while removal of two protons gives the hydrogen phosphate ion [HPO 4 ] . These names are also used for salts of those anions, such as ammonium dihydrogen phosphate and trisodium phosphate . In organic chemistry , phosphate or orthophosphate

1536-1340: Is generally denoted P i and at physiological ( homeostatic ) pH primarily consists of a mixture of [HPO 4 ] and [H 2 PO 4 ] ions. At a neutral pH, as in the cytosol (pH = 7.0), the concentrations of the orthophoshoric acid and its three anions have the ratios [ H 2 PO 4 − ] [ H 3 PO 4 ] ≈ 7.5 × 10 4 [ HPO 4 2 − ] [ H 2 PO 4 − ] ≈ 0.62 [ PO 4 3 − ] [ HPO 4 2 − ] ≈ 2.14 × 10 − 6 {\displaystyle {\begin{aligned}{\frac {[{\ce {H2PO4-}}]}{[{\ce {H3PO4}}]}}&\approx 7.5\times 10^{4}\\[4pt]{\frac {[{\ce {HPO4^2-}}]}{[{\ce {H2PO4-}}]}}&\approx 0.62\\[4pt]{\frac {[{\ce {PO4^3-}}]}{[{\ce {HPO4^2-}}]}}&\approx 2.14\times 10^{-6}\end{aligned}}} Thus, only [H 2 PO 4 ] and [HPO 4 ] ions are present in significant amounts in

1600-482: Is higher than that of N. This can be seen by analyzing the waste of organisms. Cattle urine has shown that there is a depletion of N relative to the diet. As organisms eat each other, the N isotopes are transferred to the predators. Thus, organisms higher in the trophic pyramid have accumulated higher levels of N ( and higher δ N values) relative to their prey and others before them in the food web. Numerous studies on marine ecosystems have shown that on average there

1664-401: Is not fully known, it is assumed to be similar to that of collagen ; approximately 10 years. Consequently, should an individual remain in a region for 10 years or longer, the isotopic oxygen ratios in the bone hydroxyapatite would reflect the isotopic oxygen ratios present in that region. Teeth are not subject to continual remodelling and so their isotopic oxygen ratios remain constant from

1728-671: Is predominantly sourced from dietary protein, while the carbon found in bone mineral is sourced from all consumed dietary carbon, included carbohydrates, lipids, and protein. Nitrogen isotopes can be used to infer soil conditions, with enriched δ15N used to infer the addition of manure . A complication is that enrichment also occurs as a result of environmental factors, such as wetland denitrification , salinity , aridity , microbes , and clearance . δ13C and δ15N measurements on medieval manor soils has shown that stable isotopes can differentiate between crop cultivation and grazing activities, revealing land use types such as cereal production and

1792-419: Is removed from the water at a faster rate than N, resulting in more N entering the aquifer. N is roughly 10-20‰ as opposed to the natural N values of 2-8‰. The inorganic nitrogen that is emitted from septic tanks and other human-derived sewage is usually in the form of NH 4 + {\displaystyle {\ce {NH4+}}} . Once the nitrogen enters the estuaries via groundwater, it

1856-511: Is thought that because there is more N entering, that there will also be more N in the inorganic nitrogen pool delivered and that it is picked up more by producers taking up N. Even though N is easier to take up, because there is much more N, there will still be higher amounts assimilated than normal. These levels of δ N can be examined in creatures that live in the area and are non migratory (such as macrophytes , clams and even some fish). This method of identifying high levels of nitrogen input

1920-401: Is typically rare can have significant ecological consequences. For example, blooms in the populations of some organisms at the expense of others, and the collapse of populations deprived of resources such as oxygen (see eutrophication ) can occur. In the context of pollution, phosphates are one component of total dissolved solids , a major indicator of water quality, but not all phosphorus is in

1984-409: The arbuscular mycorrhizal pathway and the direct uptake pathway. Hyperphosphatemia , or a high blood level of phosphates, is associated with elevated mortality in the general population. The most common cause of hyperphosphatemia in people, dogs, and cats is kidney failure. In cases of hyperphosphatemia, limiting consumption of phosphate-rich foods, such as some meats and dairy items and foods with

Beachy Head Lady - Misplaced Pages Continue

2048-433: The flow of energy through a food web , to reconstruct past environmental and climatic conditions, to investigate human and animal diets, for food authentification, and a variety of other physical, geological, palaeontological and chemical processes. Stable isotope ratios are measured using mass spectrometry , which separates the different isotopes of an element on the basis of their mass-to-charge ratio . Isotopic oxygen

2112-606: The hydroxyl groups have been replaced by fluoride ions. Phosphates are medicinal salts of phosphorus. Some phosphates, which help cure many urinary tract infections , are used to make urine more acidic. To avoid the development of calcium stones in the urinary tract, some phosphates are used. For patients who are unable to get enough phosphorus in their daily diet, phosphates are used as dietary supplements, usually because of certain disorders or diseases. Injectable phosphates can only be handled by qualified health care providers. Plants take up phosphorus through several pathways:

2176-442: The phosphagens in muscle tissue. Similar reactions exist for the other nucleoside diphosphates and triphosphates . An important occurrence of phosphates in biological systems is as the structural material of bone and teeth. These structures are made of crystalline calcium phosphate in the form of hydroxyapatite . The hard dense enamel of mammalian teeth may contain fluoroapatite , a hydroxy calcium phosphate where some of

2240-594: The shells of the Colorado Delta clam was used to assess the historical extent of the estuary in the Colorado River Delta prior to construction of upstream dams. A recent development in forensic science is the isotopic analysis of hair strands. Hair has a recognisable growth rate of 9-11mm per month or 15 cm per year. Human hair growth is primarily a function of diet, especially drinking water intake. The stable isotopic ratios of drinking water are

2304-444: The Beachy Head Lady was likely of Southern European origin from Cyprus, which resulted in the parish ordering the removal of a plaque erected by the BBC "to commemorate the first black Briton." Beachy Head Lady was aged around 22 to 25 when she died, and would have stood between 4 feet 9 inches and 5 feet 1 inch (1.45 m and 1.55 m) tall. The Beachy Head Lady was exhibited to the public for

2368-467: The Earth's history (glacials) such as during the ice ages , O is preferentially evaporated from the colder oceans, leaving the slightly heavier and more sluggish O behind. Organisms such as foraminifera which combine oxygen dissolved in the surrounding water with carbon and calcium to build their shells therefore incorporate the temperature-dependent O to O ratio. When these organisms die, they settle out on

2432-597: The United States) account for about 70% of world production. In ecological terms, because of its important role in biological systems, phosphate is a highly sought after resource. Once used, it is often a limiting nutrient in environments , and its availability may govern the rate of growth of organisms. This is generally true of freshwater environments, whereas nitrogen is more often the limiting nutrient in marine (seawater) environments. Addition of high levels of phosphate to environments and to micro-environments in which it

2496-400: The acid is completely dissociated as the phosphate ion, (PO 4 ) . This means that salts of the mono- and di-phosphate ions can be selectively crystallised from aqueous solution by setting the pH value to either 4.7 or 9.8. In effect, H 3 PO 4 , H 2 (PO 4 ) and H(PO 4 ) behave as separate weak acids because the successive p K

2560-433: The atmosphere, and Cañon Diablo meteorite respectively. Analysis is usually done using a mass spectrometer, detecting small differences between gaseous elements. Analysis of a sample can cost anywhere from $ 30 to $ 100. Stable isotopes assist scientists in analyzing animal diets and food webs by examining the animal tissues that bear a fixed isotopic enrichment or depletion vs. the diet. Muscle or protein fractions have become

2624-628: The average phosphate rock has roughly 3.7% phosphorus by weight. Some phosphate rock deposits, such as Mulberry in Florida, are notable for their inclusion of significant quantities of radioactive uranium isotopes. This is a concern because radioactivity can be released into surface waters from application of the resulting phosphate fertilizer . In December 2012, Cominco Resources announced an updated JORC compliant resource of their Hinda project in Congo-Brazzaville of 531 million tons, making it

Beachy Head Lady - Misplaced Pages Continue

2688-552: The average rock (while, for perspective, its typical concentration in vegetation is 0.03% to 0.2%), and consequently there are quadrillions of tons of phosphorus in Earth's 3×10 -ton crust, albeit at predominantly lower concentration than the deposits counted as reserves, which are inventoried and cheaper to extract. If it is assumed that the phosphate minerals in phosphate rock are mainly hydroxyapatite and fluoroapatite, phosphate minerals contain roughly 18.5% phosphorus by weight. If phosphate rock contains around 20% of these minerals,

2752-468: The best quality, have been mined excessively. Rock phosphate can also be found in Egypt, Israel, Palestine, Western Sahara, Navassa Island , Tunisia, Togo, and Jordan, countries that have large phosphate-mining industries. Phosphorite mines are primarily found in: In 2007, at the current rate of consumption, the supply of phosphorus was estimated to run out in 345 years. However, some scientists thought that

2816-404: The cytosol (62% [H 2 PO 4 ] , 38% [HPO 4 ] ). In extracellular fluid (pH = 7.4), this proportion is inverted (61% [HPO 4 ] , 39% [H 2 PO 4 ] ). Inorganic phosphate can also be present as pyrophosphate anions [P 2 O 7 ] , which give orthophosphate by hydrolysis : Organic phosphates are commonly found in

2880-928: The diets of past people; these isotopic systems can be used with others, such as strontium or oxygen, to answer questions about population movements and cultural interactions, such as trade. Carbon isotopes are analysed in archaeology to determine the source of carbon at the base of the foodchain. Examining the C / C isotope ratio, it is possible to determine whether animals and humans ate predominantly C3 or C4 plants. Potential C3 food sources include wheat , rice , tubers , fruits , nuts and many vegetables , while C4 food sources include millet and sugar cane. Carbon isotope ratios can also be used to distinguish between marine, freshwater, and terrestrial food sources. Carbon isotope ratios can be measured in bone collagen or bone mineral ( hydroxylapatite ), and each of these fractions of bone can be analysed to shed light on different components of diet. The carbon in bone collagen

2944-422: The discriminations. Sulfur tends to be more plentiful in less aerobic areas, such as benthic systems and marsh plants, than the pelagic and more aerobic systems. Thus, in the benthic systems, there are smaller δ S values. Nitrogen isotopes indicate the trophic level position of organisms (reflective of the time the tissue samples were taken). There is a larger enrichment component with δ N because its retention

3008-432: The energy flow in an ecosystem. The transfer of C through trophic levels remains relatively the same, except for a small increase (an enrichment < 1 ‰). Large differences of δ C between animals indicate that they have different food sources or that their food webs are based on different primary producers (i.e. different species of phytoplankton, marsh grasses.) Because δ C indicates the original source of primary producers,

3072-452: The existence of a common origin. Researchers have also shown that analysis of the C/ C ratios can locate the country of origin for a given explosive. Stable isotopic analysis has also been used in the identification of drug trafficking routes. Isotopic abundances are different in morphine grown from poppies in south-east Asia versus poppies grown in south-west Asia. The same is applied to cocaine that

3136-474: The first time at the Eastbourne Redoubt . In 2021, the remains were moved to the newly refurbished "Beachy Head Story" visitor centre, closer to where they were found. Isotope analysis Isotope analysis is the identification of isotopic signature , abundance of certain stable isotopes of chemical elements within organic and inorganic compounds . Isotopic analysis can be used to understand

3200-496: The form of esters as nucleotides (e.g. AMP , ADP , and ATP ) and in DNA and RNA . Free orthophosphate anions can be released by the hydrolysis of the phosphoanhydride bonds in ATP or ADP. These phosphorylation and dephosphorylation reactions are the immediate storage and source of energy for many metabolic processes. ATP and ADP are often referred to as high-energy phosphates , as are

3264-490: The formation of cellulose. A study on the isotope ratios of tissues from plants growing within a small area in Texas found tissues from CAM plants were enriched in deuterium relative to C4 plants. Hydrogen isotope ratios in animal tissue reflect diet, including drinking water, and have been used to study bird migration and aquatic food webs. Carbon isotopes aid us in determining the primary production source responsible for

SECTION 50

#1733092753581

3328-585: The isotopes can also help us determine shifts in diets, both short term, long term or permanent. These shifts may even correlate to seasonal changes, reflecting phytoplankton abundance. Scientists have found that there can be wide ranges of δ C values in phytoplankton populations over a geographic region. While it is not quite certain as to why this may be, there are several hypotheses for this occurrence. These include isotopes within dissolved inorganic carbon pools (DIC) may vary with temperature and location and that growth rates of phytoplankton may affect their uptake of

3392-439: The isotopes. δ C has been used in determining migration of juvenile animals from sheltered inshore areas to offshore locations by examining the changes in their diets. A study by Fry (1983) studied the isotopic compositions in juvenile shrimp of south Texas grass flats. Fry found that at the beginning of the study the shrimp had isotopic values of δ C = -11 to -14‰ and 6-8‰ for δ N and δ S. As the shrimp matured and migrated offshore,

3456-510: The isotopic values changed to those resembling offshore organisms (δ C= -15‰ and δ N = 11.5‰ and δ S = 16‰). While there is no enrichment of S between trophic levels, the stable isotope can be useful in distinguishing benthic vs. pelagic producers and marsh vs. phytoplankton producers. Similar to C, it can also help distinguish between different phytoplankton as the key primary producers in food webs. The differences between seawater sulfates and sulfides (c. 21‰ vs -10‰) aid scientists in

3520-464: The largest measured and indicated phosphate deposit in the world. Around 2018, Norway discovered phosphate deposits almost equal to those in the rest of Earth combined. In July 2022 China announced quotas on phosphate exportation. The largest importers in millions of metric tons of phosphate are Brazil 3.2, India 2.9 and the USA 1.6. The three principal phosphate producer countries (China, Morocco and

3584-514: The more resistant phosphate groups, rather than the less abundant hydroxyl group or the more likely diagenetic carbonate groups present. Isotope analysis has widespread applicability in the natural sciences . These include numerous applications in the biological , earth and environmental sciences . Archaeological materials, such as bone, organic residues, hair, or sea shells, can serve as substrates for isotopic analysis. Carbon , nitrogen and zinc isotope ratios are used to investigate

3648-556: The most common animal tissue used to examine the isotopes because they represent the assimilated nutrients in their diet. The main advantage to using stable isotope analysis as opposed to stomach content observations is that no matter what the status is of the animal's stomach (empty or not), the isotope tracers in the tissues will give us an understanding of its trophic position and food source. The three major isotopes used in aquatic ecosystem food web analysis are C, N and S . While all three indicate information on trophic dynamics , it

3712-451: The nitrogen rich water is delivered into coastal areas. Waste-water nitrate has higher concentrations of N than the nitrate that is found in natural soils in near shore zones. For bacteria, it is more convenient for them to uptake N as opposed to N because it is a lighter element and easier to metabolize. Thus, due to bacteria's preference when performing biogeochemical processes such as denitrification and volatilization of ammonia, N

3776-401: The phosphoric acid is practically undissociated. Around pH 4.7 (mid-way between the first two p K a values) the dihydrogen phosphate ion, [H 2 PO 4 ] , is practically the only species present. Around pH 9.8 (mid-way between the second and third p K a values) the monohydrogen phosphate ion, [HPO 4 ] , is the only species present. At pH 13 or higher,

3840-409: The presence of fertilization practices at historical sites. To obtain an accurate picture of palaeodiets, it is important to understand processes of diagenesis that may affect the original isotopic signal. It is also important for the researcher to know the variations of isotopes within individuals, between individuals, and over time. Isotope analysis has been particularly useful in archaeology as

3904-513: The sea bed, preserving a long and invaluable record of global climate change through much of the Quaternary . Similarly, ice cores on land are enriched in the heavier O relative to O during warmer climatic phases ( interglacials ) as more energy is available for the evaporation of the heavier O isotope. The oxygen isotope record preserved in the ice cores is therefore a "mirror" of the record contained in ocean sediments. Oxygen isotopes preserve

SECTION 60

#1733092753581

3968-416: The stable isotope composition of water are evaporation and condensation . Variability in water isotopes is used to study sources of water to streams and rivers, evaporation rates, groundwater recharge, and other hydrological processes. The ratio of O to O in ice and deep sea cores is temperature dependent, and can be used as a proxy measure for reconstructing climate change . During colder periods of

4032-608: The time of formation. The isotopic oxygen ratios, then, of teeth represent the ratios of the region in which the individual was born and raised. Where deciduous teeth are present, it is also possible to determine the age at which a child was weaned . Breast milk production draws upon the body water of the mother, which has higher levels of O due to the preferential loss of O through sweat, urine, and expired water vapour. While teeth are more resistant to chemical and physical changes over time, both are subject to post-depositional diagenesis . As such, isotopic analysis makes use of

4096-432: The various phosphates because of their key roles in biochemistry , biogeochemistry , and ecology , and their economic importance for agriculture and industry. The addition and removal of phosphate groups ( phosphorylation and dephosphorylation ) are key steps in cell metabolism . Orthophosphates can condense to form pyrophosphates . The phosphate ion has a molar mass of 94.97 g/mol, and consists of

#580419