Homework#2        Ocean Chemistry

1. The river-borne minerals can not explain the ocean’s salinity. When we make a comparison about the composition of salts in the rivers and that in the seawater, we can find out the differences. Tom Garrison (1998) mentioned that “River water is usually a dilute solution of calcium and bicarbonate ions, while the principle ions in seawater are chloride and sodium.” Besides, the percentage of magnesium in the rivers and that in the seawater are not the same. Therefore, we can prove that the minerals washed to the sea in rivers are not the same types with the minerals that dominate the salinity of seawater.

2. Because currents’ movement and circulation can make seawater’s constituent distributed more evenly by thorough mixing. In 1865, Forchhammer found out that “the percentage of various salts in seawater is the same in samples from many places, regardless of how salty the water is (Tom Garrison, 1998).” This is the Forchhammer’s principle. However, Dittmar found out some research results are different from the result of Forchhammer’s work in 1884. That is, “the values of Ca2+ for deep waters were found to be 0.3% higher than surface waters. This is due to the dissolution of CaCO3 in deep waters (Frank J. Millero et al, 2008).” Besides, Edward D. Goldberg (1960) also mentioned that Forchhammer “attempted to utilize the salinity differences for the tracing of water masses and the influences of melting ice masses and rivers upon the oceans.” Such being the case, deep water, melting ice masses and rivers upon the oceans may be the locations where the ratio of major salts to each other is not typical.

Reference:

1. Edward D. Goldberg (1960). “Chemists and the Oceans.” Chymia, Vol. 6, p.171.

2. Frank J. Millero et al (2008). “The composition of Standard Seawater and the definition of the Reference-Composition Salinity Scale.” Deep-Sea ResearchΙ, vol. 55, p.55.

3. Tom Garrison (1998). Oceanography: An Innovation to Marine Science (3^rd Ed.).p.144, Belmont, United States: Wadsworth Press.