The "Dead Zone" (Gulf of Mexico)
03 March 2025
19:35
B11305113 林榮泰
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The Gulf of Mexico is a basin and a part of the Atlantic Ocean that lies between the lands of the
US and Mexico (hence, the name). And every summer, a large part of that Gulf of Mexico
experiences significant oxygen depletion because of agricultural runoff from the Mississippi
River basin, which carries large amounts of nitrogen. It is important to note that this
phenomenon is caused by humans—more precisely—the agricultural sector, not natural causes.
A big chunk of the farmlands around our Mississippi River are corn and soybean crops. These
farmlands depend on fertilizers with high levels of nitrogen and phosphorus. Because of the lack
of filtering of the wastewater from those farmlands, the nitrogen and phosphorus sediments are
carried by the waters of the Mississippi River straight to the Gulf of Mexico. These pollutants
foster the growth of phytoplankton, to the point where there are too much of them—which in
turn—increase organic waste (phytoplankton dead bodies). The waste then gets rapidly
decomposed by bacteria, which pillage oxygen levels—constraining other aquatic life. This
constraint—in effect—reduces the size of shrimp, inhibiting reproduction functions of fish,
lowers their number overall, and creates wastelands of dead aquatic life on coastlines around the
gulf. The area of the Gulf of Mexico affected by this pollution is hence named the "Dead Zone",
which during summer peaks can span up to 22730 km² (https://www.noaa.gov/mediarelease/gulf-of-mexico-dead-zone-is-largest-ever-measured).
To put it briefly, this nitrogen pollution is caused by industrial agricultural waste—polluting the
water—and affects aquatic life wellbeing. We now know that the agricultural sector wants to
maximize crop yield and minimize algae growth coming from fertilizer waste (nitrogen waste).
How do we do this? To do it, there is a solution called cover crop planting. Cover crops are
grass planted when it isn't planting season—in other words—plants planted to prevent the soils to
be empty. When the farmlands are empty right after harvesting season, the nutrients and
fertilizing sediments trapped in the soils get washed away by waters and flows right to the ocean.
To prevent this, cover crops are planted to trap the nutrients in the farmlands, acting like a filter.
Other than that, cover crop roots hold the soil and water content in the farmland, preventing
flooding and other effects.
I believe this solution of cover crop planting is quite beneficial and not difficult to implement by
agricultural sectors. As an effect of our industrialization and the needs of the mass, we need to
change our polluting habits and change for the goal of sustainability—not only paying attention
to our carbon and plastic footprint, but our all sorts of wastes and pollution.
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