Researchers assess effects of a world awash in nitrogen

December 15, 2011

Humans are having an effect on Earth’s ecosystems but it’s not just the depletion of resources and the warming of the planet we are causing. Now you can add an over-abundance of nitrogen as another “footprint” humans are leaving behind. The only question is how large of an impact will be felt.

In a Perspectives piece in the current issue of Science (Dec. 16, 2011), Arizona State University researcher James Elser outlines some recent findings on the increasing abundance of available nitrogen on Earth. In “A World Awash in Nitrogen,” Elser, a limnologist, comments on a new study showing that disruption to Earth’s nitrogen balance began at the dawn of the industrial era and was further amplified by the development of the Haber-Bosch process to produce nitrogen rich fertilizers. Download Full Image

Until that time nitrogen, an essential building block to life on Earth and a major but inert component of its atmosphere, had cycled at low but balanced levels over millennia. That balance ended around 1895.

“Humans have more than doubled the rate of nitrogen inputs into global ecosystems, relative to pre-industrial periods, and have changed the amounts of circulating phosphorus (like nitrogen, a key limiting ingredient for crops and other plants) by about 400 percent due to mining to produce fertilizers,” Elser said.

The result has been immediate and widespread, he added.

Commenting on a major new finding in Science by G.W. Holtgrieve and colleagues, Elser said that signs of the “new N” appeared in all regions of the Northern Hemisphere in a remarkably coherent manner beginning around 1895, in concert with when fossil fuel combustion and large scale biomass burning accelerated across the globe. Another significant increase came around 1970 coincident with massive increases in industrial nitrogen fixation for fertilizer production, just as the “Green Revolution” got started.

The effects of the high nitrogen inputs “were immediate, and no place in the Northern Hemisphere – not even the highest reaches of the Arctic – was safe,” Elser stated.

One effect from the increased nitrogen inputs can be seen in our inland water features like lakes, reservoirs and rivers.

“Nitrogen deposition to lakes leads to phytoplankton (at the base of food chain) with low content of the important nutrient phosphorus,” Elser said. “This is kind of like ‘junk food,’ for animals that eat the phytoplankton. Such effects are likely to ripple upward in the food chain.”    

“Overall, changes in nutrient regimes (due to human acceleration of the nitrogen and phosphorus cycles) cause various problems, but especially reduction in water quality, in water supplies and deterioration of coastal marine fisheries (‘dead zones’),” Elser added. “In the U.S., conservative estimates indicate that nutrient over-enrichment of inland waters results in about $2.7 billion of annual economic costs annually, due to negative impacts on recreational water usage, waterfront real estate values, the cost of recovery of threatened and endangered species and drinking water provisions.”

On a grander timeline the effects could be more telling of humans themselves, Elser said.

“Whether such signals are an ephemeral blip in the stratigraphic record or a sustained shift lasting millennia may, in due time, be seen as an indicator of humanity’s success, or failure, in achieving planetary sustainability,” he added.

Director, Media Relations and Strategic Communications


Alumni Association to host Sparky's Touchdown Tailgate at MAACO Bowl

December 16, 2011

The ASU Alumni Association will celebrate the Sun Devil football team's participation in the MAACO Bowl Las Vegas, Dec. 22, with a special pre-bowl Sparky's Touchdown Tailgate.

The tailgate, co-hosted by the Alumni Association and the Sun Devil Club, will be from 2 to 4:30 p.m. (PST), Dec. 22, at Sam Boyd Stadium, 7000 E. Russell Road, Las Vegas. It will be headlined by special guest speakers that include ASU President Michael Crow and former Sun Devil football player Jeff van Raaphorst, a quarterback who was the Most Valuable Player in ASU’s 1987 Rose Bowl victory. ASU is bowl bound Download Full Image

The event will also feature appearances by the ASU marching band, Spirit Squad and Sparky the Sun Devil. Included in the entry price is a meal with barbeque chicken and beef brisket as entrées, as well as a no-host bar. Members of the ASU Alumni Association receive a special gift at the tailgate if they show their alumni card.

The tailgate is one of several special events preceding the bowl game. On Dec. 21, marching bands from ASU and Boise State will battle it out at a Fremont Street Experience Pep Rally, scheduled to be held at 425 Freemont Street from 6 to 7:30 p.m. The rally is free and open to the public.

Tickets to the tailgate are $40 when purchased online and $45 at the door; a comprehensive bowl package, which includes the tailgate, a ticket to the game and round-trip shuttle service from Mandalay Bay Resort to the tailgate, is available online for $115.

For more information on the pre-bowl tailgate, or to order game/tailgate ticket packages, visit