Too Much of a Good Thing: Nutrient Pollution

Apr 14, 2015

 Too Much of a Good Thing, Nutrient Pollution in engineering
John Lacy, P.E.

Take a deep breath.  Almost 80 percent of what you just inhaled was nitrogen.  It's too bad that you can’t use it – the bonds are too strong for us to break -- and yet we’d die without it!  So where do we get a usable form of this vital nutrient?  Well, it’s part of the cycle of life; rain carries it from the air to the soil, soil carries it to the plants, animals eat plants, and we eat plants and animals.  Thanks to waste and bacteria, the limited amount of usable nitrogen returns to the air and soil to begin the process again.  If nitrogen doesn’t make it back to the air or soil, fewer plants can grow and that means less animals and people can survive.  In order to prevent this, a German chemist figured out in 1909 how to create nitrogen fertilizer from air to feed plants.  Today, hydrogen from natural gas and nitrogen from air are combined to make nitrogen fertilizer using this same basic process.

Thanks to fracking and cheap natural gas, our country is the world leader in natural gas production; making us number 2 and 3 in nitrogen fertilizer consumption and production.  In fact, the United States applies over 20 million tons of fertilizer each year, with roughly 13 million tons of nitrogen and 5 million tons of phosphorus, respectively.  

That's a whole lot of a good thing.  And that's not all!  

While the United States is no longer the wheat "breadbasket of the world," it is the world leader in corn production with over 96 million acres of dedicated land and a record 14 billion bushels produced in 2013 -- 20% of which was exported to feed the world.  As the world population continues to grow, along with the additional 2006 ethanol requirements, the demand for corn will only increase.  And wouldn't you know, the crops that require the most nitrogen per acre are...you guessed it:  wheat and corn.  Boom!

So it's no surprise that “nutrient pollution is one of America's most widespread, costly and challenging environmental problems, and is caused by excess nitrogen and phosphorus in the air and water,” according to the Environmental Protection Agency website.  In 2007, the EPA reported that 1 in every 4 water body impairments was nutrient-related.  As a result, the EPA and state agencies started measuring what the actual and desired nutrient levels were in each waterway.  The desired reduction was then divided and assigned to the sewage treatment plants along the waterway.  If the waterway nutrient levels needed to be reduced a lot, the amount of reduction could require significant plant modifications to achieve. Ouch.

To better understand how nutrient pollution harms the environment, imagine dumping a jug of Miracle-Grow fertilizer into a small fish pond.  The plants, algae, and bacteria would thrive until the pond was clogged.  However, as the plants and algae died, bacteria would decompose the plants and algae, using up most of the oxygen in the water.  The lack of oxygen would then kill the fish.  The bacteria would use more oxygen to decompose the dead fish, killing even more fish.  If nutrient levels get too high, this vicious cycle can quickly impair or destroy a waterway and cause color, odor, taste, and turbidity problems.  Certain bacteria can produce dangerous toxins that can contaminate a drinking water supply.  

But nitrogen and phosphorus levels don't get out of balance through fertilizer use alone.  Actually, motor vehicles and livestock manure add to nitrous greenhouse gases.  Sewage treatment plant discharges include controlled amounts of these nutrients, as well.  Phosphate-containing detergents also play a role.

So, where do we begin?  Most importantly, tell a friend and increase public awareness.  But other ways to help minimize nutrient pollution are: obviously use less fertilizer, choose phosphate-free detergents, try using less detergent altogether by maximizing each dishwashing/washing machine load, pick up after your pet, minimize garbage disposal use, inspect and regularly pump out your septic system, use efficient water fixtures/appliances, be energy efficient, wash your car at a car wash, and minimize driving.  That way, we can leave the expression "too much of a good thing" for things like dessert.

 

Sources:
EPA (Nutrient Pollution) - http://www2.epa.gov/nutrientpollution
USDA (Fertilizer) - http://www.ers.usda.gov/data-products/fertilizer-use-and-price.aspx
USDA (Corn) - http://www.ers.usda.gov/topics/crops/corn/background.aspx
USDA (Wheat) - http://www.ers.usda.gov/topics/crops/wheat/background.aspx

Comments
Post has no comments.
Post a Comment




Captcha Image

Blog Categories

Recent Posts

Archive