Although the salinity of ocean water varies from place to place, the relative amounts of the different salts do not vary significantly. Briefly explain why this is so?
The relative amounts of different salts in ocean water do not vary significantly because the composition of seawater is primarily controlled by the processes of evaporation and precipitation, known as the water cycle. Let me explain why this is so:
1. The water cycle: Water on Earth evaporates from the surface, forming water vapor, which then condenses and falls back to the Earth as precipitation. This process is continuously happening, maintaining the water cycle. However, when water evaporates, it leaves behind the dissolved salts in the water.
2. Salts in seawater: When rainwater falls on the land, it carries tiny amounts of dissolved salts. These salts come from various sources, including weathering of rocks, minerals in the soil, and volcanic activity. These salt-laden rainwaters eventually flow into rivers and ultimately reach the oceans.
3. Mixing and circulation: Once in the oceans, the water mixes and circulates due to various factors like currents, winds, and tides. This mixing helps to distribute the salts evenly throughout the ocean, creating a relatively homogenous composition.
4. Constant inputs and outputs: While some salts are continuously being added to the ocean through rivers and other sources, there are also mechanisms by which salts are removed from seawater, such as the formation of marine sediments and precipitation of minerals. These processes help maintain a balance in the overall concentration and relative amounts of different salts over time.
5. Conservative elements: It is also important to note that certain elements that make up the majority of the dissolved solids in seawater, like sodium, chloride, magnesium, potassium, and calcium, behave as conservative elements. This means that they are relatively unaffected by biological or chemical processes in the ocean, further contributing to the stability in the relative amounts of salts.
In conclusion, the relative amounts of different salts in ocean water remain relatively stable due to the continuous water cycle's processes, mixing and circulation in the ocean, constant inputs and outputs of salts, and the behavior of conservative elements.