Air Quality Research Demonstrates Our Ecosystem’s Interdependence

Sophisticated air quality research is proving not only what many of us already knew — that the air we breathe is essential to good health and a long life — but also the far-reaching effects of atmospheric pollution. Air quality is literally a top-down issue, affecting air, soil, water and every living thing.Air Quality Research

A recent example of this is research from a team of Stanford University scientists that proves the link between nitrogen oxides in the air and diminished crop yields. The findings, published last year in the journal Science Advances, established that nitrogen oxides target crop cells while boosting the production of ozone in the atmosphere. In turn, ozone reduces the amount of sunlight crops in the field receive.

After analyzing the study, The Stanford News Service reported: “Based on their observations, the researchers estimated that reducing NOx emissions by about half in each region would improve yields by about 25% for winter crops and 15% for summer crops in China, nearly 10% for both winter and summer crops in Western Europe, and roughly 8% for summer crops and 6% for winter crops in India. North and South America generally had the lowest NOx exposures. Overall, the effects seemed most negative in seasons and locations where NOx likely drives ozone formation.”

In addition to boosting ozone, nitrogen oxides interact with ammonia, which often is present in the atmosphere in agricultural areas where nitrogenous fertilizers are widely used. This interaction “can result in increased concentrations of ammonium nitrate aerosols and can also oxidize sulfur dioxide and drive formation of ammonium sulfate aerosols,” according to the Stanford scientists.

“These particles reflect and scatter incoming sunlight, changing the radiation environment experienced by crops and reducing access to photosynthetically active radiation.”

Although nitrogen oxides are negatively impacting crop yields around the world, nitrogen itself is essential to healthy soil, notes Canadian microbiologist Hamza Mbareche. “Farmers have a great respect for nitrogen, just as they do for all natural systems,” says Mbareche.

“They know that plants need nitrogen in the soil to thrive. They also know that only certain types of plants such as legumes are able to convert atmospheric nitrogen into a nutrient for the soil, which is why legumes such as lentils, clover and peas play important roles in crop rotations in organic agriculture.”

Fertilizer is a major source for both nitrates in the soil and nitrogen oxides in the air. When overused, it degrades the quality of the soil, air and nearby streams. It leeches into groundwater and finds its way into streams.

But the chain reaction doesn’t stop there, explains Mbareche: “When nitrogen run-off reaches the ocean, it promotes the growth of algae. At the end of its life cycle, this plethora of algae sinks to the bottom of the sea and is decomposed by bacteria. But that process uses up oxygen in the water, depriving fish and other oceanic life of the oxygen they need to survive.”

This has been happening for decades, and the result is that vast “dead zones” extend across large bodies of water across the globe. Both the Chesapeake Bay and the Gulf of Mexico today feature these kinds of dead zones, where aquatic life cannot survive.