Subtropical waters are typically more saline than equatorial waters because of the bigger temperature and much lower precipitation.
The precipitation manages to lower the salinity on the surface of the water even create ''pools'' with fresh water in the middle of the saline water. In the equatorial region there's rain almost every day, so the salinity is lower, while in the subtropical regions there's seasonal rain and it is in much lower amount, the temperature is higher which makes the water evaporate more and the salt to be more concentrated, thus the higher salinity.
b) warm & wet
Hope I helped! ( Smiles )
When two tectonic plates push towards each other, one continental, and another oceanic, the oceanic plate is subducting under the continental plate. This is due to the fact that the oceanic plates's crust is weaker and has lesser density, while the continental is stronger and has bigger density, so when pushing against each other, the weaker, less dense, oceanic plate can not oppose the stronger, more dense, continental plate and slowly subducts under it.
Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, aquifers and groundwater). This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds.
Water pollution affects the entire biosphere – plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and population, but also to the natural biological communities.