Studies in the Terrestrial Biosphere, the Atmosphere, and Ice Cores

Starting with the work of Ben Houlton, we have collaborated with the group of Lars Hedin in the Department of Ecology and Evolutionary Biology in isotope studies of terrestrial N cycling. We have also worked on the nitrate N and O isotopes in rain, snow, and ice as tracers of reactive nitrogen sources and processing in the modern and ancient atmosphere.

Hawaiian rainforest

A photo taken by former graduate student Ben Houlton of a Hawaiian rainforest. See Houlton et al. (2006).

References

AuthorTitleTypeYear
5 Publications
Applied Filters: First Letter Of Last Name: H Reset
Glacial/interglacial changes in the isotopes of nitrate from the Greenland Ice Sheet Project 2 (GISP2) ice core
M.G. Hastings, D.M. Sigman, E.J. Steig

The 15N/14N and 18O/16O ratios of nitrate in the Greenland Ice Sheet Project 2 (GISP2) (Summit, Greenland) ice core are much higher in ice from the last glacial period than in the pre-industrial Holocene, despite the lack of a significant glacial/interglacial change in nitrate concentration. While both the 15N/14N and 18O/16O records are…

Seasonal variations in N and O isotopes of nitrate in snow at Summit, Greenland: Implications for the study of nitrate in snow and ice cores
M.G. Hastings, E.J. Steig, D.M. Sigman

Nitrogen and oxygen isotopes of NO3- have been measured in snow and firn from Summit, Greenland. The 15N/ 14N and 18O/16O ratios of NO 3- in recently fallen snow are similar to those of surface snow. Diurnal variation is observed in 15N/ 14N of NO3-, and possibly 18O/16O, suggesting fractionating loss of NO3- from snow during the day, which is…

Isotopic evidence for source changes of nitrate in rain at Bermuda
M.G. Hastings, D.M. Sigman, F. Lipschultz

Rainwater collected on the island of Bermuda between January 2000 and January 2001 shows pronounced seasonal variation in the nitrogen and oxygen isotopic composition of nitrate. Higher 15N/14N and lower 18O/16O ratios are observed in the warm season (April-September) in comparison to the cool season (October-March): The mean δ15N of nitrate…

A climate-driven switch in plant nitrogen acquisition within tropical forest communities
B.Z. Houlton, D.M. Sigman, E.A.G. Schuur, L.O. Hedin

The response of tropical forests to climate change will depend on individual plant species nutritional strategies, which have not been defined in the case of the nitrogen nutrition that is critical to sustaining plant growth and photosynthesis. We used isotope natural abundances to show that a group of tropical plant species with diverse growth…

Isotopic evidence for large gaseous nitrogen losses from tropical rainforests
B.Z. Houlton, D.M. Sigman, L.O. Hedin

The nitrogen isotopic composition (15N/14N) of forested ecosystems varies systematically worldwide. In tropical forests, which are elevated in 15N relative to temperate biomes, a decrease in ecosystem 15N/14N with increasing rainfall has been reported. This trend is seen in a set of well characterized Hawaiian rainforests, across which we have…