|To the previous article||To the next article|
Nitrate, ammonia and phosphate are the three nutrients that have the most impact on aquatic ecosystems. In the Mississippi River basin Nitrogen inputs have been the largest concern. There are nitrate inputs of natural sources and these are vital for the survival of the ecosystem. Over the years, however, human nitrogen inputs have far surpassed natural ones and anthropogenic sources are approximated to comprise 75% of the nitrogen being released into the Mississippi River (Antweiler and Taylor). Most of that is a result of nonpoint pollution from agricultural runoff from the large amounts of fertilizer being applied to agricultural fields (Antweiler and Taylor). The fact that nutrient levels are higher as you move downstream demonstrates that they are being put into the system faster than they are being removed (Antweiler and Taylor). The Upper Mississippi River contributes the largest percentage of nitrate in the Mississippi River, with more than half of the nitrate coming from that area. The Ohio River on the other hand though it contributes the largest volume of water adds only 21 percent of the total nitrates (Antweiler, Goolsby, and Taylor).