Understanding the oceans' nitrogen cycle becomes more crucial every year as scientists recognize that the planet's delicate nitrogen balance is changing rapidly. Humans have doubled the rate at which nitrogen moves between land and sea -- the most severe human effect in all of global chemistry. A 1997 report published by the Ecological Society of America, a professional organization of about 8,000 environmental scientists, outlines a potentially catastrophic combination: ignorance of the global nitrogen cycle mixed with an unparalleled level of human nitrogen tampering. The ESA warns that humans are setting changes in motion without perceiving the consequences.
The use of nitrogen-based fertilizers accounts for most nitrogen-cycle vandalism, and humans use more every year. World agriculture used more nitrogen fertilizer in the 1980s than in the entire history of agriculture prior to 1980. A great amount of that fertilizer finds its way to the oceans. The ammonia in fertilizers flees readily into the air, and from there, the nitrogen is just one rainy step from the sea.
"We're basically fertilizing the oceans," Ward says. "And we will see a measurable effect. It may have already started in the deep oceans, but we can only monitor the surface." Scientists know too little about the oceans to predict the impact of ocean fertilization, but Ward says that it might be jarring. Many marine plants and animals depend on nature's supply of nitrogen-based nutrients. In coastal estuary systems, nitrogen poisoning has already caused the population of a few species of algae to explode. The thick swarms of algae appear as brown and red tides which choke fish, plants, and even birds.
Ward says that certain types of bacteria might be able to process some of the excess nitrogen, in effect softening humanity's careless blow.
For watching the interplay of nitrogen and bacteria, there is no better venue than the salty confines of Lake Bonney . The capped lake lacks many of the complications that make the study of ocean chemistry difficult -- namely rain, fish, and the mixing of water caused by wind and strong currents. Other scientists are watching Ward's work in Antarctica, hoping it will reveal the private inner workings of the oceans.
One lobe of Lake Bonney provides an example of chemistry and bacteria in harmony, while the other provides an example of what can go wrong. Nitrous oxide is the most alarming of the east lobe's wealth of nitrogen-based chemicals. A bucket of water from the east lobe contains 5,000 times more nitrous oxide gas than a bucket of ocean water. The lake holds so much nitrous oxide and other gases that the water bubbles when Ward and her colleagues haul it to the surface.
By analyzing chemicals deposited deep in Antarctic glaciers, scientists have found that the atmosphere contains more nitrous oxide today than it has for the last 45,000 years. Nitrous oxide is a greenhouse gas, meaning it contributes to global warming. Though carbon dioxide is at least 50 times more abundant, nitrous oxide packs more of a warming punch in each molecule.
Commonly known as laughing gas, nitrous oxide does not just billow from dentists' offices. Industrial sources of nitrous oxide include nylon manufacturing, fossil-fuel burning, and nitrogen fertilizing. When all these sources are added together, they still do not completely account for the abundance of nitrous oxide. Natural factors are also at play, but scientists don't fully understand these factors -- especially the role of oceans and ocean bacteria.
Lake Bonney is too small to contribute significantly to global increases of nitrous oxide; nevertheless, scientists tie the chemical questions of Lake Bonney to a prognosis for the joint health of the oceans and the atmosphere. In December of 1997, the National Science Foundation decided to fund Ward's continuing work on Lake Bonney with half a million dollars -- 10 times the average NSF research grant.