How does water carry dissolved chemicals and sediments from land to the ocean?

Water carries dissolved chemicals and sediments from land to the ocean primarily through fluvial processes, which involve the interaction of flowing water with river channels and drainage basins.1

Transport of Sediments

Sediments are moved from land to the ocean through two main mechanisms within river systems:
* Bed load: Larger particles are rolled, pushed, or saltated (jumped) along the riverbed.1
* Suspended load: Smaller particles, such as silt and clay, are picked up and carried in the water column for long distances.12

These materials originate from the erosion of hills and valley slopes by rain, frost, and wind, as well as the scouring of riverbeds by the water itself. Once these sediments reach the river mouth, they are often deposited to form deltas or are dispersed into the ocean by currents and waves.1345

Transport of Dissolved Chemicals

Dissolved chemicals enter the hydrosphere through weathering reactions, where acid solutions in the soil attack rock minerals.2
* Congruent weathering: Entire solids dissolve, releasing elements like calcium and bicarbonate into soil waters and groundwaters, which eventually drain into rivers.2
* Incongruent weathering: Only part of a solid is consumed, creating new minerals (such as clay) while releasing dissolved constituents like potassium and silica into the water.2

These dissolved substances are transported by rivers to the ocean, where they contribute to the chemical composition of seawater.26