Calcium carbonate and the carbonic acid system

2011 ◽  
Keyword(s):  
Calcium Carbonate ◽  
Carbonic Acid ◽  
Acid System

Porewater CO2–carbonic acid system chemistry in permeable carbonate reef sands

2016 ◽  
Vol 185 ◽  
pp. 48-64 ◽  
Author(s):  
Patrick S. Drupp ◽  
Eric Heinen De Carlo ◽  
Fred T. Mackenzie
Keyword(s):  
Carbonic Acid ◽  
Acid System ◽  
System Chemistry

scholarly journals Latitudinal Trends and Drivers in the CO2–Carbonic Acid System of Papahānaumokuākea Marine National Monument

2015 ◽  
Vol 21 (6) ◽  
pp. 535-553 ◽  
Author(s):  
Andrea K. Kealoha ◽  
Samuel E. Kahng ◽  
Fred T. Mackenzie ◽  
Simone R. Alin ◽  
Randall K. Kosaki ◽  
...  
Keyword(s):  
Carbonic Acid ◽  
Acid System ◽  
National Monument

The causes and effects of aging in quick clays

1985 ◽  
Vol 22 (3) ◽  
pp. 335-346 ◽  
Author(s):  
Ghislain Lessard ◽  
James K. Mitchell
Keyword(s):  
Calcium Carbonate ◽  
Pore Water ◽  
Iron Sulfide ◽  
Carbonic Acid ◽  
Iron Hydroxide ◽  
Liquid Limit ◽  
Key Words Aging ◽  
Liquidity Index ◽  
Aging Phenomenon ◽  
Effects Of Aging

The physicochemical properties of a clay from La Baie, Quebec were found to be typical of Champlain quick clays: very low plasticity, liquidity index greater than 3, sensitivity greater than 500, and pH of about 9.5. The mineralogy is characterized by the abundance of primary or "rock flour" minerals such as feldspar, quartz, amphibole, and calcite, with illite as the principal clay mineral. The pore water chemistry consists predominantly of sodium bicarbonate. Low concentrations of sulfate, calcium, and magnesium and high alkalinity and pH are attributed, in part, to anaerobic sulfate-reduction processes taking place in situ.Quick clay samples stored in the laboratory showed signs of aging regardless of the storage procedure. The remoulded strength and the liquid limit increased with time, whereas the sensitivity, the liquidity index, and the pH decreased. The water content, plastic limit, and undisturbed strength remained practically unchanged. The pore water concentrations of calcium, magnesium, and sulfate increased by severalfold.The aging phenomenon is attributed, for the most part, to the oxidation of iron sulfide, which results in the formation of iron hydroxide and sulfuric acid. The production of acid causes the dissolution of calcium carbonate, which increases the concentration of divalent cation in the clay, thereby reducing interparticle repulsion and increasing the remoulded strength. The oxidation of organic matter, resulting in the formation of carbonic acid, also contributes to the aging by its effect on the solubility of calcium carbonate. Key words: aging, chemical reactions, physicochemical phenomena, sensitivity, time effects.

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