Soil erodes into waterways which spill into oceans.
Btw, the nutrients that the soil carries can cause spikes in algal populations, which then lower the oxygen content of water bodies, killing large numbers of other organisms like fish.
> spikes in algal populations, which then lower the oxygen content of water bodies
How can algae lower oxygen when oxygen is the very byproduct of their photosynthesis? They literally turn water into oxygen. Wouldn't that increase the oxygen content?
This is similar to how mulch works to suppress weed growth. Mulch is decaying matter and nutrients like nitrogen are temporarily 'locked up' during the decay process.
Btw, the nutrients that the soil carries can cause spikes in algal populations, which then lower the oxygen content of water bodies, killing large numbers of other organisms like fish.