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32-522: Kirov Bridge (Belarusian: Кіраўскі мост) is a bridge, on the Dzvina river, in the city of Vitsebsk in northern Belarus. This article about a bridge in Belarus is a stub . You can help Misplaced Pages by expanding it . Dzvina Latvia's capital, Riga , bridges the river's estuary four times. Built on both riverbanks, the city centre is 15 kilometres (9.3 mi) from the river's mouth and

64-538: 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

96-592: A derivative of orthophosphoric acid, a.k.a. phosphoric acid H 3 PO 4 . The phosphate or orthophosphate ion [PO 4 ] 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

128-471: 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

160-623: 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

192-473: 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

224-684: A key location of settlement and defence of the mouth of the Daugava at least as early as the Middle Ages, as evidenced by the now destroyed fort at Torņakalns on the west bank of the Daugava in present-day Riga. From the end of the Livonian War great part of the Daugava formed the northeastern border of Duchy of Courland and Semigallia saparating it initially from the Kingdom of Livonia , later Swedish Livonia and Riga Governorate . After

256-829: 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

288-450: 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,

320-657: Is a significant port. According to Max Vasmer 's Etymological Dictionary , the toponym Dvina cannot stem from a Uralic language ; instead, it possibly comes from an Indo-European word which used to mean river or stream . The name Dvina resembles strongly Danuvius which itself derived from the Proto-Indo-European *dānu , meaning "large river". The Finno-Ugric names Vēna ( Livonian ), Väinajogi ( Estonian ), and Väinäjoki ( Finnish ) all stem from Proto-Finnic *väin , meaning "a large, peacefully rolling river". The total catchment area of

352-484: 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

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384-1340: 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

416-401: 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

448-409: 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

480-606: 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:

512-442: 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

544-481: The Baltic. In Belarus, water pollution of the Daugava is considered moderately severe, with the chief sources being treated wastewater, fish-farming, and agricultural chemical runoff (such as herbicides, pesticides, nitrates, and phosphates). Phosphate In chemistry , a phosphate is an anion , salt , functional group or ester derived from a phosphoric acid . It most commonly means orthophosphate ,

576-604: 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

608-400: 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

640-641: 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

672-604: 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,

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704-472: 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

736-653: The cities and towns built along the Daugava: The river began experiencing environmental deterioration in the Soviet era due to collective agriculture (producing considerable adverse water pollution runoff) and hydroelectric power projects. This is the river that the Vula river flows into. Upstream of the Latvian town of Jekabpils , the river's pH has a characteristic value of about 7.8 (slight alkaline ). In this area,

768-519: The concentration of ionic calcium is around 43 milligrams per liter, nitrate is about 0.82 milligrams per liter, ionic phosphate is 0.038 milligrams per liter, and oxygen saturation is 80%. The high nitrate and phosphate load of the Daugava has contributed to the extensive buildup of phytoplankton biomass in the Baltic Sea; the Oder and Vistula rivers also contribute to the high nutrient loading of

800-404: 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

832-502: 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

864-536: The incorporation later in the Russian Empire the river formed a border between governorates of Courland on the western bank and Livonia and Vitebsk on the eastern bank. From 1936 to 1939 Ķegums Hydroelectric Power Station was built on the Daugava river in Latvia. Pļaviņas Hydroelectric Power Station was put into operation in 1968 and Riga Hydroelectric Power Plant in 1974. The following are some of

896-467: 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

928-401: 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,

960-507: The river is 87,900 km (33,900 sq mi), of which 33,150 km (12,800 sq mi) are in Belarus. The following rivers are tributaries to the river Daugava (from source to mouth): Humans have settled at the mouth of the Daugava and along the shores of the Gulf of Riga for millennia, initially participating in a hunter-gatherer economy and utilizing the waters of the Daugava estuary for fishing and gathering. Beginning around

992-632: The sixth century CE, Viking explorers crossed the Baltic Sea and entered the Daugava River, navigating upriver into the Baltic interior. In medieval times, the Daugava was part of the trade route from the Varangians to the Greeks , an important route for the transport of furs from the north and of Byzantine silver from the south. The Riga area, inhabited by the Finnic -speaking Livs , became

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1024-432: 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

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