Question

which human activity contributes most to excess phosphorus in aquatic ecosystems? industrial emissions overharvesting forests fossil fuel combustion

Explanation:

Synthetic fertilizers are rich in phosphorus. When used in agriculture, excess phosphorus can runoff into aquatic ecosystems, contributing significantly to excess phosphorus levels. Industrial emissions, overharvesting forests and fossil - fuel combustion do not directly contribute as much to excess phosphorus in aquatic ecosystems as the use of synthetic fertilizers.

Answer:

Use of synthetic fertilizers