Nutrient runoff from the Mississippi watershed and ecosystem pollution risk in the Northern Gulf of Mexico

Since the discovery of synthetic ammonia in 1909, the usage of synthetic fertilizers in agricultural lands has massively increased. Water from rain and melting snow washes down excess fertilizer from farmlands into water bodies and subsequently into oceans, causing ocean eutrophication, a phenomenon of excessive nutrient accumulation. The Mississippi River Basin, the largest in North America, drains about 41 percent of the United States (U.S.). The river discharges an estimated 1.6 million metric tons of nutrient fertilizer per year into the Gulf of Mexico (GOM). This substantial influx of nutrients supports excessive algal blooms in the coastal waters of the GOM. These giant algal masses eventually die, sink, decompose, and deplete the oxygen in the water, devastating aquatic habitats. GOM has exhibited the largest oceanic dead zone in the US, spanning over 20,000 km 2 in some years. Such colossal dead zones occur every summer and have been linked to the massive destruction of marine habitats and a sustainability challenge for the coastal waters. This paper discusses the primary causes and far-reaching effects of eutrophication on GOM, and how this critical crisis could be sustainably mitigated.