Answer :
Final answer:
Hydrothermal vents contribute to the addition and removal of minerals in the deep ocean, with the superheated water causing precipitation of metal sulfides. This precipitation process is the reason why vents do not have a significant impact on average ocean salinity over long timescales. Option B
Explanation:
Hydrothermal vents are a significant feature of the deep ocean where superheated water, rich in minerals, is expelled into the ocean. These vents play a role in both the addition and removal of ionic substances from seawater, which affects the ocean chemistry.
Within hydrothermal vent systems, seawater percolates into the oceanic crust, becomes superheated by underlying magma, and then rises back to the ocean floor, carrying with it dissolved minerals. When this superheated water encounters the cold seawater, the precipitation process occurs, leading to the formation of metal sulfides that fall out as sediment.
Over long timescales, these processes do not significantly alter average ocean salinity due to the vastness of the ocean, which dilutes these minerals extensively. The option B, Precipitation, is the primary reason the metal-rich waters from the vents do not have a notable effect on overall ocean salinity.
This process of precipitation allows many of the dissolved substances to settle out of the water column before they can contribute to changes in broad-scale salinity. Option B
