I believe the answer is that under natural conditions oceans are self-cleaning systems.
By immigration migrating to one location to the other
Although India shared some of the same ideals as other countries that
obtained their independence during the same time, there were profound
differences between the Indian independence movement and other other
nations. For example, unlike Egypt and some other Middle Eastern
countries, Indians have managed to preserve civilian rule throughout the
almost 50 years that they have been free...................... Hope this helps
The answer to your question is knowledge. Scientific knowledge is the information gathered by the systematic study of nature.