Question: Base-richness in ecology is the level in water or soil of chemical bases, such as calcium or magnesium ions, changes in the levels of acids (such as dissolved carbon dioxide) may significantly change acidity without affecting base-richness, Carbonic acid is a chemical compound with which chemical formula ? 
Context: Ocean acidification is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO ) from the atmosphere.  Seawater is slightly basic (meaning pH > 7), and the process in question is a shift towards pH-neutral conditions rather than a transition to acidic conditions (pH < 7).  Ocean alkalinity is not changed by the process, or may increase over long time periods due to carbonate dissolution.  An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes.  To achieve chemical equilibrium, some of it reacts with the water to form carbonic acid.  Some of these extra carbonic acid molecules react with a water molecule to give a bicarbonate ion and a hydronium ion, thus increasing ocean acidity (H ion concentration).  Between 1751 and 1996 surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of almost 35% in H ion concentration in the world's oceans.  Earth System Models project that within the last decade ocean acidity exceeded historical analogues and in combination with other ocean biogeochemical changes could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean. A deaerator is a device that is widely used for the removal of oxygen and other dissolved gases from the feedwater to steam-generating boilers.  In particular, dissolved oxygen in boiler feedwaters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust).  Dissolved carbon dioxide combines with water to form carbonic acid that causes further corrosion.  Most deaerators are designed to remove oxygen down to levels of 7 ppb by weight (0.005 cm³/L) or less as well as essentially eliminating carbon dioxide. In marine and reef aquariums, a calcium reactor creates a balance of alkalinity.  An acidic solution is produced by injecting carbon dioxide into a chamber with salt water and calcium rich media.  The carbon dioxide lowers the pH by producing a solution high in carbonic acid, and dissolves calcium.  The effluent is returned to the reef aquarium where the calcium is consumed by organisms, primarily corals when building skeletons.  A calcium reactor is an efficient method to supply calcium to a reef aquarium.  Reactors may be used in elaborate freshwater and brackish aquariums where freshwater clams and other invertebrates need a constant supply of calcium. Calcium bicarbonate, also called calcium hydrogen carbonate, has a chemical formula Ca(HCO).  The term does not refer to a known solid compound; it exists only in aqueous solution containing the calcium (Ca), bicarbonate (HCO), and carbonate (CO) ions, together with dissolved carbon dioxide (CO).  The relative concentrations of these carbon-containing species depend on the pH; bicarbonate predominates within the range 6.36-10.25 in fresh water. Dry ice color show is the formation of carbonic acid (HCO) by the reaction of dry ice, the solid form of carbon dioxide (CO), and water.  The reaction between these 2 compounds lower the pH of the solution, therefore making the solution more acidic.  Dry ice has a temperature of –78.5 °C and normally exist in gas state.  By applying universal indicator to the solution, the changing of the pH can be indicated as the color of the solution changes into the contrast color.  This experiment is usually conducted as a classroom demonstration of pH and properties of carbon dioxide since the materials required are handful and can be prepared easily.  Solid carbon dioxide can cause frostbite when in contact with the skin, by sticking to the moist tissue, such as wet skin or tongue.  Solid carbon dioxide undergoes sublimation upon exposure to air.  This means it transforms directly from the solid phase to the gaseous phase without melting into liquid. Carbonic acid is a chemical compound with the chemical formula HCO (equivalently OC(OH)).  It is also a name sometimes given to solutions of carbon dioxide in water (carbonated water), because such solutions contain small amounts of HCO.  In physiology, carbonic acid is described as "volatile acid" or "respiratory acid", because it is the only acid excreted as a gas by the lungs.  It plays an important role in the bicarbonate buffer system to maintain acid–base homeostasis. Senebier was greatly influenced by Swiss naturalist Charles Bonnet.  Senebier was also influenced by the Italian animal physiologist and experimental biologist Lazzaro Spallanzani, several of whose works Senebier translated from Italian into French.  Spallanzani's chemical research on bodily functions of animals helped lead Senebier towards studying plant chemistry.  Although Senebier's first research on plants was a large study on effects of light, he is remembered mainly for the extensive evidence he provided that carbon dioxide ("fixed air" or "carbonic acid," in the terminology of his day) is consumed by plants in the production of oxygen ("dephlogisticated air"), in the physiological process that later became known as photosynthesis.  Senebier also found that the amount of oxygen produced is roughly proportional to the amount of carbon dioxide available to the plant.  Further, he determined that the green fleshy parts of leaves (the parenchyma) are the sites where carbon dioxide is transformed into oxygen.  Senebier also correctly concluded that plants use the carbon in carbon dioxide as a nutriment.  Senebier did some of his research jointly with fellow Swiss naturalist François Huber. The total inorganic carbon ("C", or TIC) or dissolved inorganic carbon (DIC) is the sum of inorganic carbon species in a solution.  The inorganic carbon species include carbon dioxide, carbonic acid, bicarbonate anion, and carbonate.  It is customary to express carbon dioxide and carbonic acid simultaneously as CO* .  "C" is a key parameter when making measurements related to the pH of natural aqueous systems, and carbon dioxide flux estimates. A bicarbonate indicator (hydrogencarbonate indicator) is a type of pH indicator that is sensitive enough to show a color change as the concentration of carbon dioxide gas in an aqueous solution increases.  The indicator is used in photosynthesis and respiration experiments to find out whether carbon dioxide is being liberated.  It is also used to test the carbon dioxide content during gaseous exchange of organisms.  When the carbon dioxide content is higher than 0.04%, the initial red color changes to yellow as the pH becomes more acidic.  If the carbon dioxide content is lower than 0.04%, it changes from red to magenta and, in relatively very low carbon dioxide concentrations, to purple.  Carbon dioxide, even in the concentrations found in exhaled air, will dissolve in the indicator to form carbonic acid, a weak acid, which will lower the pH and give the characteristic colour change.  A colour change to purple during photosynthesis shows a reduction in the percentage of carbon dioxide and is sometimes inferred as production of oxygen, but there is not actually any direct evidence for it. Base-richness in ecology is the level in water or soil of chemical bases, such as calcium or magnesium ions.  Many organisms are restricted to base-rich environments.  Chemical bases are alkalis, and so base-rich environments are neutral or alkaline.  Because base-poor environments have few bases, they are dominated by environmental acids (usually organic acids) and so are acidic.  However, the relationship between base-richness and acidity is not a rigid one – changes in the levels of acids (such as dissolved carbon dioxide) may significantly change acidity without affecting base-richness.
Answer: HCO