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30-467: The River Stiffkey is a chalk stream running through an area of north Norfolk , England from its source near Swanton Novers to flow out into the North Sea on the north Norfolk coast near the village of Stiffkey . The river has been dredged historically, presumably for agricultural purposes, and has a self-sustaining population of brown trout . The river's source is a small wooded lake just north of

60-409: A buffer to stabilise it in the range 7.37–7.43: Exhaled CO 2 (g) depletes CO 2 (aq) , which in turn consumes H 2 CO 3 , causing the equilibrium of the first reaction to try to restore the level of carbonic acid by reacting bicarbonate with a hydrogen ion, an example of Le Châtelier's principle . The result is to make the blood more alkaline (raise pH). By the same principle, when

90-583: A model with fractional bonds and delocalized charges: Metal carbonates generally decompose on heating, liberating carbon dioxide leaving behind an oxide of the metal. This process is called calcination , after calx , the Latin name of quicklime or calcium oxide , CaO, which is obtained by roasting limestone in a lime kiln : As illustrated by its affinity for Ca , carbonate is a ligand for many metal cations. Transition metal carbonate and bicarbonate complexes feature metal ions covalently bonded to carbonate in

120-464: A temporary reservoir by regulating the amount of water supplied to the springs. This is why many chalk streams in the UK have stable flow regimes that vary only slightly over time. The temperature of the emerging surface water is fairly stable and rarely deviates from 10 °C (50 °F). On cold winter mornings, water vapour from the relatively warm stream condenses in the cold air above to form fog. Chalk

150-406: A variety of bonding modes. Lithium , sodium , potassium , rubidium , caesium , and ammonium carbonates are water-soluble salts, but carbonates of 2+ and 3+ ions are often poorly soluble in water. Of the insoluble metal carbonates, CaCO 3 is important because, in the form of scale , it accumulates in and impedes flow through pipes. Hard water is rich in this material, giving rise to

180-402: Is double bonded. These compounds are also known as organocarbonates or carbonate esters, and have the general formula R−O−C(=O)−O−R′ , or RR′CO 3 . Important organocarbonates include dimethyl carbonate , the cyclic compounds ethylene carbonate and propylene carbonate , and the phosgene replacement, triphosgene . Three reversible reactions control the pH balance of blood and act as

210-458: Is prone to flooding and was the subject of a severe flood warning in October 2004. The river is probably named after the village of Stiffkey, whose name means "Island with tree-stumps". Chalk stream The beds of the rivers are generally composed of clean, compacted gravel and flints , which are good spawning areas for Salmonidae fish species. Since they are fed primarily by aquifers ,

240-441: Is related to the disparate lattice energies of solids composed of mono- vs dianions, as well as mono- vs dications. In aqueous solution , carbonate, bicarbonate, carbon dioxide, and carbonic acid participate in a dynamic equilibrium . In strongly basic conditions, the carbonate ion predominates, while in weakly basic conditions, the bicarbonate ion is prevalent. In more acid conditions, aqueous carbon dioxide , CO 2 (aq) ,

270-480: Is slightly soluble in rainwater because rain is naturally slightly acidic . The products of chalk weathering are dissolved in rainwater and are transported in stream flow. Chalk streams transport little suspended material (unlike most rivers), but are considered " mineral -rich" due to the dissolved calcium and carbonate ions . The surface water of chalk streams is commonly described as "gin clear". The channel bed consists of angular flint gravel derived from

300-444: Is the main form, which, with water, H 2 O , is in equilibrium with carbonic acid – the equilibrium lies strongly towards carbon dioxide. Thus sodium carbonate is basic, sodium bicarbonate is weakly basic, while carbon dioxide itself is a weak acid. In organic chemistry a carbonate can also refer to a functional group within a larger molecule that contains a carbon atom bound to three oxygen atoms, one of which

330-453: Is the simplest oxocarbon anion . It consists of one carbon atom surrounded by three oxygen atoms, in a trigonal planar arrangement, with D 3h molecular symmetry . It has a molecular mass of 60.01  g/mol and carries a total formal charge of −2. It is the conjugate base of the hydrogencarbonate (bicarbonate) ion, HCO − 3 , which is the conjugate base of H 2 CO 3 , carbonic acid . The Lewis structure of

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360-574: The River Thames , River Lea and River Colne ): Chalk streams of the Yorkshire Wolds : Chalk streams of Lincolnshire : There are several chalk streams in the Lincolnshire Wolds including Chalk streams of Kent: Chalk streams of Norfolk: Chalk streams of Suffolk: Carbonate A carbonate is a salt of carbonic acid , ( H 2 CO 3 ), characterized by the presence of

390-445: The carbonate ion , a polyatomic ion with the formula CO 2− 3 . The word "carbonate" may also refer to a carbonate ester , an organic compound containing the carbonate group O=C(−O−) 2 . The term is also used as a verb, to describe carbonation : the process of raising the concentrations of carbonate and bicarbonate ions in water to produce carbonated water and other carbonated beverages – either by

420-476: The 210 rivers classified as chalk streams globally, 160 are in England. A list of chalk streams in England gives a total of 224. Chalk is a highly porous and permeable rock, and rain falling onto chalk topography percolates directly into the ground, where the chalk layer acts as an aquifer . The groundwater flows through the chalk bedrock, re-emerging lower down the slope in springs . The chalk acts as

450-399: The UK has caused the chalk streams to dry up. This has caused ecological damage and stagnant sewage that flows through the rivers and increasing phosphate levels. Although chalk streams are generally watercourses originating from chalk hills, including winterbournes , streams, and rivers, the term chalk stream is used even for larger rivers, which would normally be considered too large for

480-512: The addition of carbon dioxide gas under pressure or by dissolving carbonate or bicarbonate salts into the water. In geology and mineralogy , the term "carbonate" can refer both to carbonate minerals and carbonate rock (which is made of chiefly carbonate minerals), and both are dominated by the carbonate ion, CO 2− 3 . Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock . The most common are calcite or calcium carbonate , CaCO 3 ,

510-514: The best conditions for fly fishing , and most specifically, dry fly fishing . The chalk streams hold a good number of wild salmonid fish species such as the brown trout ( Salmo trutta ), and grayling ( Thymallus thymallus ). In addition to these there are also considerable numbers of stocked brown trout and stocked rainbow trout ( Oncorhynchus mykiss ). The rich invertebrate life and characteristic transparent shallow water make chalk rivers and streams particularly suited to fly fishing. Many of

540-459: The carbonate ion has two (long) single bonds to negative oxygen atoms, and one short double bond to a neutral oxygen atom. This structure is incompatible with the observed symmetry of the ion, which implies that the three bonds are the same length and that the three oxygen atoms are equivalent. As in the case of the isoelectronic nitrate ion, the symmetry can be achieved by a resonance among three structures: This resonance can be summarized by

570-610: The chalk stream springs are also used as sites for watercress production, due to the constant temperature and clean, alkaline , mineral-rich spring water. The Mid Hants Watercress Railway in Hampshire is so named on account of its use for transporting watercress to London from local chalk streams. A number of the chalk aquifers and associated groundwater sources related to chalk streams and rivers are used for water abstraction by local and national water utility companies. The over-abstracting of chalk streams by private water companies in

600-453: The chief constituent of limestone (as well as the main component of mollusc shells and coral skeletons); dolomite , a calcium-magnesium carbonate CaMg(CO 3 ) 2 ; and siderite , or iron(II) carbonate , FeCO 3 , an important iron ore . Sodium carbonate ("soda" or "natron"), Na 2 CO 3 , and potassium carbonate ("potash"), K 2 CO 3 , have been used since antiquity for cleaning and preservation, as well as for

630-436: The flow rate, mineral content and temperature range of chalk streams exhibit less seasonal variation than other rivers. They are mildly alkaline and contain high levels of nitrate , phosphate , potassium and silicate . In addition to algae and diatoms , the streams provide a suitable habitat for macrophytes (including water crowfoot ) and oxygen levels are generally supportive of coarse fish populations. Of

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660-473: The long-term carbon cycle, due to the large number of marine organisms (especially coral) which are made of calcium carbonate. Increased solubility of carbonate through increased temperatures results in lower production of marine calcite and increased concentration of atmospheric carbon dioxide. This, in turn, increases Earth temperature. The amount of CO 2− 3 available is on a geological scale and substantial quantities may eventually be redissolved into

690-435: The manufacture of glass . Carbonates are widely used in industry, such as in iron smelting, as a raw material for Portland cement and lime manufacture, in the composition of ceramic glazes , and more. New applications of alkali metal carbonates include: thermal energy storage, catalysis and electrolyte both in fuel cell technology as well as in electrosynthesis of H 2 O 2 in aqueous media. The carbonate ion

720-470: The natural flint deposits found embedded within the chalk geology that contains relatively low amounts of clay and silt deposits. The unique characteristics of chalk stream ecology are due to stable temperature and flow regimes combined with highly transparent water and lack of sand grade sediment particles. The chalk streams have been intensively managed for many generations. In the 20th and 21st centuries, much of that management has been aimed at producing

750-412: The need for infrastructural water softening . Acidification of carbonates generally liberates carbon dioxide : Thus, scale can be removed with acid. In solution the equilibrium between carbonate, bicarbonate, carbon dioxide and carbonic acid is sensitive to pH, temperature, and pressure. Although di- and trivalent carbonates have low solubility, bicarbonate salts are far more soluble. This difference

780-410: The pH is too high, the kidneys excrete bicarbonate ( HCO − 3 ) into urine as urea via the urea cycle (or Krebs–Henseleit ornithine cycle). By removing the bicarbonate, more H is generated from carbonic acid ( H 2 CO 3 ), which comes from CO 2 (g) produced by cellular respiration . Crucially, a similar buffer operates in the oceans. It is a major factor in climate change and

810-412: The sea and released to the atmosphere, increasing CO 2 levels even more. It is generally thought that the presence of carbonates in rock is strong evidence for the presence of liquid water. Recent observations of the planetary nebula NGC 6302 show evidence for carbonates in space, where aqueous alteration similar to that on Earth is unlikely. Other minerals have been proposed which would fit

840-715: The term stream . The Somme in northern France is a chalk stream on a larger scale. Winterbournes are known by different names depending on region: Chalk streams of the Southern England Chalk Formation in Berkshire , Hampshire , Wiltshire , Dorset and the Isle of Wight : Chalk streams of the Southern England Chalk Formation in the Chiltern Hills , Hertfordshire and Surrey (tributaries of

870-549: The village of Swanton Novers, after which the river passes close to Fulmodeston , then north to pass through the village of Great Snoring , which is noted in the Domesday book as having a watermill . From Great Snoring it runs south past Thorpland Hall, then north-west through East Barsham , North Barsham and Houghton St Giles to Little Walsingham , the largest settlement on its course. The Priory in Little Walsingham

900-489: Was built with stone from Northamptonshire which had been towed up the River Stiffkey in flat-bottomed barges. The priory had a watermill on the river but this was demolished early in the 20th century. From here it flows north past Great Walsingham , then through Wighton and Warham before passing through the village of Stiffkey and out to its estuary on Stiffkey Salt Marshes. The area from Great Walsingham to Stiffkey

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