Nitrogen on EARTH Magazine

A rocky source of nitrogen

Tue, 03 Jul 2018 11:38:51 -0400

Calculations of the planet’s nitrogen balance have always been off: plants and soils seem to sequester far more nitrogen than expected. The atmosphere has long been thought of as the only major source of nitrogen, but a new study indicates an additional source: as much as a quarter of Earth’s terrestrial nitrogen may be supplied by eroding bedrock.

From farm to filter: Restored wetlands remediate nitrogen pollution

Mon, 09 Apr 2018 11:21:45 -0400

Bottomland hardwoods are a predominant wetland type in the Mississippi Alluvial Valley, the historic floodplain and valley of the lower Mississippi River. Credit: U.S. Fish and Wildlife Service.

Nitrogen giveth and nitrogen taketh away: It’s been estimated that roughly half of the world’s population today could not exist without nitrogen fertilization. Although land area on Earth remains roughly the same on human timescales, population continues to rise, requiring more intensive and rigorous use of existing agricultural land and the creation of more agricultural lands to meet the ever-growing demand for food. One way humanity has supported population growth is through the manipulation of nitrogen, a limiting nutrient in terrestrial ecosystems. In 1913, the advent of the Haber-Bosch process, which artificially converts nitrogen gas to bioavailable ammonia, revolutionized access to nitrogen and all but eliminated nitrogen limitation in terrestrial ecosystems. Now, nitrogen fertilizers are often heavily applied to croplands to increase plant growth and productivity.

Burning grass releases more nitrogen pollution than burning wood

Thu, 26 Jan 2017 09:50:27 -0500

Researchers found that grass and crop fires produce more nitrogen pollutants than wildfires. Credit: USFWS, CC BY 2.0.

Smoke from fires — whether from wildfires or from residential and agricultural grass and crop burning — carries pollutants into the air that affect climate and can be toxic to humans and ecosystems. According to new research, smoke from crop and grass fires appears to contain higher levels of some hazardous nitrogen-containing chemicals than wood fire smoke. The work also calls into question whether certain chemicals commonly used as distinctive signatures of biomass burning are still valid.

Nutrient deficiency delayed life after mass extinction

Tue, 15 Nov 2016 18:16:07 -0500

Stephen Grasby collects samples from an outcrop on northern Ellesmere Island in the Canadian High Arctic. Credit: John Spear, Colorado School of Mines.

After Earth’s most severe mass extinction, life took up to 9 million years to recover — millions of years longer than after other extinction events. New research published in Geology suggests that a collapse in the ocean’s productivity might have been the cause.

Convection formed Pluto's polygons

Mon, 17 Oct 2016 09:47:08 -0400

Sputnik Planum, a 900,000-square-kilometer ice-filled basin on Pluto, is home to peculiar polygonal domes. New research indicates that the polygons were formed by convection, rather than thermal contraction, within thick layers of nitrogen ice. Credit: NASA/JHUAPL/SwRI.

Among Pluto’s peculiar surface features, many of which were first seen just last year when NASA’s New Horizons spacecraft zipped by the dwarf planet, are polygon-shaped rises covering parts of a large equatorial basin known as Sputnik Planum. The basin is known to be filled mainly with ices of nitrogen, methane and carbon monoxide, but the origin of the polygons has been debated. In a pair of new studies published in Nature, two teams of researchers now attribute the distinctive shapes to convection within underlying layers of frozen nitrogen.

Uranium contamination in aquifers could be linked to nitrate

Tue, 16 Feb 2016 10:49:05 -0500

Uranium (red) and nitrate (blue) levels in groundwater are indicated at sites across the U.S. in this map, including in the Central Valley (California) and High Plains (central U.S.) aquifers. Credit: University of Nebraska--Lincoln

Nitrogen is an essential nutrient for plant life, but plants can only take up so much so fast. When excess nitrogen enters the environment by way of fertilizer and manure runoff, as well as in automobile and industrial emissions, it becomes a pollutant that can leach into waterways, carrying with it unintended — and often undesirable — consequences. In a new study, researchers have found evidence of one such consequence: elevated uranium levels in two major U.S. aquifers.

Sunlight liberates nitrogen from urban grime

Fri, 18 Dec 2015 09:46:09 -0500

Urban grime, as seen here in Manchester, England, is a mixture of thousands of chemical compounds. Credit: Pete Birkinshaw, CC by 2.0.

Cities are dirty. That’s obvious from all the grime that collects on glass, metal and other urban surfaces. But new research shows that not everything in that grunge is staying put at ground level, and that the grime — and the nitrogen in it — is contributing to air pollution in ways scientists aren’t accounting for.

Ancient lakes may have been refuges for early life

Fri, 23 Oct 2015 11:16:11 -0400

Scientists collected 1.2-billionyear- old lake sediments from this cliff at the Bay of Stoer in northwestern Scotland to measure molybdenum supply. Credit: Samuel Spinks.

All life needs nitrogen to build essential molecules like proteins, RNA and DNA. And to acquire nitrogen, cells need molybdenum. But molybdenum is thought to have been very scarce in Mesoproterozoic oceans 1.6 billion to 1 billion years ago, potentially stalling the evolution and diversification of life in this period, which was then entirely microscopic. New research, however, is revealing that lakes during this time contained relatively high levels of molybdenum, suggesting life may have continued evolving in those settings.

Thank subduction for Earth's nitrogen-rich air

Mon, 02 Feb 2015 09:47:23 -0500

The chemically oxidizing conditions in subduction zones might explain the enrichment of nitrogen (and high ratio of nitrogen to noble gases) in Earth's atmosphere compared to those on Venus and Mars, neither of which has active plate tectonics. Credit: Kathleen Cantner, AGI, after Sami Mikhail.

Plate tectonics underlies many of Earth’s distinctive features, from its ever-shifting continents to its colliding mountain ranges and continuously forming crust at mid-ocean ridges. According to a new study, the process might also explain another of our planet’s peculiarities: its nitrogen-rich atmosphere.