地质科学-自然2013-09-05 2:57 AM

Isotopic ratios of nitrite as tracers of the sources and age of oceanic nitrite : Nature Geoscience : Nature Publishing Group

Nitrite is a central intermediate in the marine nitrogen cycle, and is generally found at low concentrations in the ocean. However, nitrite accumulates at the base of the sunlit surface ocean. The origin of this ubiquitous feature, known as the primary nitrite maximum, is debated and has been difficult to resolve through short-term isotope tracer incubations. Here, we use measurements of the dual isotopic composition of nitrite to evaluate the sources, sinks and average rates of nitrite turnover in the primary nitrite maximum in the Arabian Sea. We determined the rate of abiotic oxygen isotope exchange between nitrite and water, as well as equilibrium isotope effects, under a variety of conditions in a series of laboratory experiments. We used these data to model nitrite isotope data from several sites in the Arabian Sea. The results suggest that ammonia oxidation is the primary source of nitrite at most sites. Steady-state nitrite turnover times of 33–178 days correspond to ammonia oxidation rates of 9–30 nM per day at these sites. We suggest that a similar approach could be used to determine the rates of nitrite turnover in other environments, including the secondary nitrite maximum in low-oxygen regions.

KEYWORDS

SHARE & LIKE

COMMENTS

ABOUT THE AUTHOR

地质科学-自然

0 Following 0 Fans 0 Projects 12 Articles

SIMILAR ARTICLES

Hydrogen is commonly produced during the high-temperature hydration of mafic and ultramafic rocks, owing to the oxidation of reduced iron present in th

Read More

The global mid-ocean ridge system, where tectonic plates diverge, is traditionally thought of as the largest single volcanic feature on the Earth. Yet,

Read More

Over the past 50 years, warming of the Antarctic Peninsula has been accompanied by accelerating glacier mass loss and the retreat and collapse of ice s

Read More

Over much of the ocean’s surface, productivity and growth are limited by a scarcity of bioavailable nitrogen. Sedimentary δ15N records spanning the las

Read More

The Indo-Pacific warm pool—the main source of heat and moisture to the global atmosphere—plays a prominent role in tropical and global climate variabil

Read More

Earthquakes are accompanied by coseismic and post-seismic rebound: blocks of crust on either side of the fault spring back to their initial, undeformed

Read More

Earthquakes are accompanied by coseismic and post-seismic rebound: blocks of crust on either side of the fault spring back to their initial, undeformed

Read More

Geodynamical models and seismic observations suggest that the Earth’s solid inner core rotates at a different rate than the mantle. However, discrepanc

Read More

Geodynamical models and seismic observations suggest that the Earth’s solid inner core rotates at a different rate than the mantle. However, discrepanc

Read More

The Moon experienced an intense period of impacts about 4 Gyr ago. This cataclysm is thought to have affected the entire inner Solar System and has bee

Read More