The most likely source of thermal pollution in a river ecosystem would be <span>the use of water as a </span>coolant<span> by </span>power plants<span> and industrial manufacturers</span>. One harmful effect that this type of pollution has is a sudden change in water temperature (either a rapid increase or decrease) known as "thermal shock."<span>, killing fish and other native animals.
></span>Thermal pollution<span> is defined as the degradation of </span>water quality<span> by any means that changes ambient water </span>temperature<span>.</span>
Answer:
The source of pollution that decreases the oxygen level of water are plant fertilizer and animal manure.
Explanation:
Plant fertilizer that is applied in the agricultural field when enter into the water body, causes water pollution which increases minerals into the water body and animal manure contain raw material which causes eutropication that means increase algal bloom. This indirectly decreases oxygen availability into the water body.
I believe it is the 'black swallower'
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