:) a pond near a city park is found to be contaminated with both bacteria and excess nitrogen. the bacteria most likely came from and the excess nitrogen most likely came from sediment; pesticides animal waste; fertilizers inorganic metals; sediment runoff; sewage

A pond near a city park is found to be contaminated with both bacteria and excess nitrogen. The bacteria most likely came from animal waste,and the excess nitrogen likely came from fertilizers.

The bacteria will be most likely to come from animal waste as numerous bacteria lives in the intestine and stomach of these animals, which facilitate the digestion of food, these bacteria come along the animal feces after digestion. Also, there are bacteria which degrade the animal feces. Bacteria may also degrade and may be present on other animal wastes like left out skin, tissues, hair, fur. Nitrogen is the chief constituent of fertilizers. Nitrogen increases the fertility of soil and it can be a potent pollutant for a water body.          

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.