Exploding Fertilizer and a Dead Zone

Last week saw a deadly explosion at a fertilizer plant is West, Texas. Several city blocks near the plant were leveled by the explosion, hundreds were injured and over a dozen people killed. The ultimate cause of the explosion has yet to be determined and may never be known exactly but what is known is that several hundred tons of Ammonium Nitrate had been stored there.

Accidental detonation of Ammonium Nitrate stores are rare but when they do occur they are deadly. The most recent before the West, Texas plant involved a fertilizer manufacturing plant in Iowa in 1994. There an explosion killed four and injured a couple of dozen. The granddaddy of all fertilizer explosions occurred in Texas City, Texas in 1947. A freighter in the port of Texas City carrying over two thousand tons of Ammonium Nitrate exploded, leveling the city. The explosion which knocked people off there feet in Galveston ten miles away, killed almost a thousand and injured many thousands more.

These accidents are tragic but accidents just the same. More hideous are intentional explosions such as Timothy McVeigh’s truck bomb in Oklahoma City. He used about 3 tons of fertilizer to destroy the Murrah Federal Building, in the process causing hundreds of millions of dollars of property loss and killing 168 people including 19 preschool children.

So if Ammonium Nitrate is so dangerous, why so much of it? Because as noted it is fertilizer, and a very important one at that. Historically nitrogen from animal dung has been applied to crops. Addition of Nitrogen to the soil improves plant growth, in fact without Nitrogen plants don’t grow at all.

Early in the nineteenth century a concentrated form of Nitrogen fertilizer called Chilean Saltpeter (a form of Nitrate) was obtained from South America. Later a process for manufacturing Ammonium Nitrate synthetically known as the Haber process, was developed in Germany. This process has since been employed world wide and is a key to both large scale agriculture but also large scale explosive manufacturing. Nitrate from the Haber process is used in modern explosives such as dynamite, TNT, and other even more potent munitions.

So Nitrate in explosives is bad, at least the lethality aspect is bad, but Nitrate in fertilizers is good? Up to a point yes, but too much fertilizer used as fertilizer can be bad. When any form of Nitrogen is applied to soil some of it is taken up into plants. If the applied fertilizer is in a soluble form it can wash from the soil into rivers, lakes, and water supplies. Too much Nitrate in drinking water can cause infant deaths due to a condition call Blue Baby Syndrome.

The ultimate insult to the environment from too much Nitrate in waterways is the production of algal blooms. Natural decomposition of the algae consumes oxygen in the water which can kill virtually all aquatic organisms. Every year, a dead zone develops at the mouth of the Mississippi River in the Gulf of Mexico. The dead zone is a hypoxic region, a region with little or no dissolved oxygen. The size of the region varies from year to year, but covers thousands of square miles in the late summer.

As in so many other aspects of life, too much of good thing can cause harm. We need to be good to our mother (Earth). She’s all we’ve got.

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