Artificial seawater (abbreviatedASW) is a mixture of dissolvedmineral salts (and sometimesvitamins) that simulatesseawater. Artificial seawater is primarily used inmarine biology and inmarine andreef aquaria, and allows the easy preparation ofmedia appropriate for marineorganisms (includingalgae,bacteria,plants andanimals). From ascientific perspective, artificial seawater has the advantage ofreproducibility over natural seawater since it is a standardized formula. Artificial seawater is also known as synthetic seawater and substitute ocean water.
The tables below present an example of an artificial seawater (35.00‰ of salinity) preparation devised by Kester, Duedall, Connors and Pytkowicz (1967).[1] The recipe consists of two lists of mineral salts, the first ofanhydrous salts that can be weighed out, the second ofhydrous salts that should be added to the artificial seawater as a solution.
| Salt | Molecular weight | g kg−1solution |
|---|---|---|
| Sodium chloride (NaCl) | 58.44 | 23.926 |
| Sodium sulfate (Na2SO4) | 142.04 | 4.008 |
| Potassium chloride (KCl) | 74.56 | 0.677 |
| Sodium bicarbonate (NaHCO3) | 84.00 | 0.196 |
| Potassium bromide (KBr) | 119.01 | 0.098 |
| Boric acid (H3BO3) | 61.83 | 0.026 |
| Sodium fluoride (NaF) | 41.99 | 0.003 |
| Salt | Molecular weight | mol kg−1 solution |
|---|---|---|
| Magnesium chloride (MgCl2.6H2O) | 203.33 | 0.05327 |
| Calcium chloride (CaCl2.2H2O) | 147.03 | 0.01033 |
| Strontium chloride (SrCl2.6H2O) | 266.64 | 0.00009 |
While all of the compounds listed in the recipe above areinorganic, mineral salts, some artificial seawater recipes, such as Goldman and McCarthy (1978),[2] make use of trace solutions ofvitamins ororganic compounds.
The International Standard for making artificial seawater can be found atASTM International.[3] The current standard is named ASTM D1141-98[4] (The original standard was ASTM D1141-52) and describes the standard practice for the preparation of substituteocean water. The ASTM D1141-98 standard comes in a ready-made artificial seawater form or a "Sea Salt" mix that can be prepared by engineers and hobbyists. Generally, the ready-made artificial seawater comes in 1 gallon and 5 gallon containers, whereas the "Sea Salt" mix comes in 20lb pails (makes approximately 57 gallons) and 50lb pails (makes approximately 143 gallons).
There are various applications for ASTM D1141-98 synthetic seawater includingcorrosion studies, oceaninstrument calibration and chemical processing.[5] Typically,laboratory-grade water is used when making synthetic salts.[6]