Ocean water is full of mineral salts which enter through the rivers, passing through rock and soil. Water has a property of evaporation whereas salt does not, so a lot of salt is left behind.
Oceans are saline throughout the world, but the Mediterranean Sea is saltier. Many oceans are less salty due to the regular mixing of fresh river water.
There are also other celestial sources of UV radiation.
Very large young stars shine most of their light in ultraviolet wavelengths. But the Earth's atmosphere blocks much of the UV radiation, and observations are conducted using high-altitude balloons and special orbiting telescopes equipped to observe the UV region of the EM spectrum.
The idea that food is safe to eat off the floor if you pick it up quickly is not accurate.
A study showed that in some cases, bacteria takes less than a second to transfer to food. The longer food was allowed to stay on a surface, the more bacteria was transferred to the food. The higher the moisture, the higher the risk of transfer.