Question

Where does the salt in oceans come from?

Glaciers contain salt and melt into the ocean.
Pollution from trucks adds salt into the ocean.
Minerals from the land are washed into the ocean.
Decomposing fish and plants in the ocean increase salinity.

Answer 1

Main source: minerals washed from the land.

Explanation and quick answers to each statement:
- Glaciers contain salt and melt into the ocean. Mostly false. Glaciers are largely fresh water. Sea ice can trap brine pockets, but melting glaciers generally dilute, not salt, the ocean. Any salt in ice is tiny compared with river-borne salts.
- Pollution from trucks adds salt into the ocean. Partly true but minor. Road salt and other human contaminants can reach rivers and eventually the sea, but they are a very small contribution to ocean salinity overall.
- Minerals from the land are washed into the ocean. True — this is the main source. Chemical weathering of rocks on land releases ions (especially sodium and chloride) that rivers carry to the sea. Over geologic time these inputs have accumulated and made the oceans salty.
- Decomposing fish and plants in the ocean increase salinity. Not really. Decomposition recycles dissolved ions already present in seawater (and from ingested food); it doesn’t create a long‑term net increase in ocean salt.

Other contributors: volcanic gases, hydrothermal vents at mid‑ocean ridges, and atmospheric deposition add some ions. Ocean salinity is maintained by a balance of inputs and sinks (sediment burial, formation of evaporite minerals, subduction).