Passage VII
Tiny marine organisms build shells from calcite (CaCO3) dissolved in seawater. After the organisms’ death, the shells sink. Some shells dissolve before they reach the seafloor, but some form layers of calcareous ooze (CaCO3-rich sediment). Figure 1 shows how seawater’s degree of saturation with respect to CaCO3 and the rate at which CaCO3 dissolves change with depth. The CaCO3 compensation depth (CCD) represents the depth beneath which CaCO3 dissolves faster than it precipitates. Figure 2 shows typical depths at which various seafloor sediments are found. Figure 3 shows the percent coverage for 2 seafloor sediments in 3 oceans.
38. CaCO3 often precipitates out of seawater in areas where the seawater is shallow (less than 1 km deep). According to Figure 1, this most likely occurs because seawater in those locations:
Your Answer is
Correct Answer is H
Explanation
As can be seen from figure 1, CaCO3 in shallow seawater is supersaturated, so it will precipitate and precipitate