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pH, salinity, & nutrients

Estimated change in annual mean sea surface pH between the pre-industrial period (1700s) and the present day (1990s). ΔpH here is in standard pH units.

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  • Ocean acidification troubles Featured Article Ocean acidification troubles Ocean acidification troubles

    The seas in which corals and other calcifying species dwell are turning acidic, their pH slowly dropping as Earth's oceans acidify in response to increased carbon dioxide... More »

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Ocean acidification troubles Last Updated on 2012-08-09 00:00:00 The seas in which corals and other calcifying species dwell are turning acidic, their pH slowly dropping as Earth's oceans acidify in response to increased carbon dioxide in the atmosphere. Trouble in Paradise: Ocean Acidification This Way Comes Sustainability of tropical corals in question, but some species developing survival mechanisms The following Discovery article is part two in a series on the National Science Foundation's Science, Engineering and Education for Sustainability (SEES) investment. Visit parts one, three, four, five, six and seven in this series. The following is part five in a series on the National Science Foundation's Long-Term Ecological Research (LTER) Network. Visit parts one, two, three, four, six, seven, eight and nine in this series. Double, double toil and trouble; Fire burn, and caldron bubble. —Shakespeare,... More »
More Acidic Oceans: A Threat to Coral, Mollusks, and Seaweed Last Updated on 2010-12-16 00:00:00 Rising atmospheric carbon dioxide concentrations have increased dissolved inorganic carbon (abbreviated as DIC) consisting of carbon dioxide (CO2), bicarbonate ions (HCO3-), and carbonate ions (CO3 2-). Increased levels of DIC have, in turn, increased water acidity. If atmospheric CO2 concentrations climb from 350 parts per million (ppm) to 1000 ppm, as they well may do, the DIC in a glass of pure water sitting on your table will go from 14.1 micromoles per liter (µmol L-1) to 37.4 µmol L-1, and its pH will decrease from 5.65 to 5.42. Such a pH shift may seem nominal, but pH is based on a logarithmic scale, and so the corresponding proton concentrations in the glass will increase 70%, from 2.2 µmol L-1 to 3.8 µmol L-1. Seawater, because of the salts dissolved in it, is significantly more alkaline than pure water. The pH of seawater now averages 8.1, which... More »
Sea water Last Updated on 2009-11-02 00:00:00   Sea Water   If there is one thing that just about everyone knows about the ocean is that it is salty. The two most common elements in sea water, after oxygen and hydrogen, are sodium and chloride. Sodium and chloride combine to form what we know as salt. Sea water salinity is expressed as a ratio of salt (in grams) to liter of water. In sea water typically there are close to 35 grams of dissolved salts in each liter. This concentration is written as 35‰. The normal range of ocean salinity ranges between 33-37 grams per liter (33‰ - 37‰). As in weather, where there are circumstances of high and low pressure, there are situations characterized by high as well as low salinity. Of the Earth's five ocean basins, the Atlantic Ocean is the saltiest. On average, there is a distinct decrease of salinity near the equator and... More »