| Title |
Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change
|
|---|---|
| Published in |
Proceedings of the National Academy of Sciences of the United States of America, April 2014
|
| DOI | 10.1073/pnas.1319441111 |
| Pubmed ID | |
| Authors |
Lei Geng, Becky Alexander, Jihong Cole-Dai, Eric J. Steig, Joël Savarino, Eric D. Sofen, Andrew J. Schauer |
| Abstract |
Nitrogen stable isotope ratio (δ(15)N) in Greenland snow nitrate and in North American remote lake sediments has decreased gradually beginning as early as ∼1850 Christian Era. This decrease was attributed to increasing atmospheric deposition of anthropogenic nitrate, reflecting an anthropogenic impact on the global nitrogen cycle, and the impact was thought to be amplified ∼1970. However, our subannually resolved ice core records of δ(15)N and major ions (e.g., NO3(-), SO4(2-)) over the last ∼200 y show that the decrease in δ(15)N is not always associated with increasing NO3(-) concentrations, and the decreasing trend actually leveled off ∼1970. Correlation of δ(15)N with H(+), NO3(-), and HNO3 concentrations, combined with nitrogen isotope fractionation models, suggests that the δ(15)N decrease from ∼1850-1970 was mainly caused by an anthropogenic-driven increase in atmospheric acidity through alteration of the gas-particle partitioning of atmospheric nitrate. The concentrations of NO3(-) and SO4(2-) also leveled off ∼1970, reflecting the effect of air pollution mitigation strategies in North America on anthropogenic NO(x) and SO2 emissions. The consequent atmospheric acidity change, as reflected in the ice core record of H(+) concentrations, is likely responsible for the leveling off of δ(15)N ∼1970, which, together with the leveling off of NO3(-) concentrations, suggests a regional mitigation of anthropogenic impact on the nitrogen cycle. Our results highlight the importance of atmospheric processes in controlling δ(15)N of nitrate and should be considered when using δ(15)N as a source indicator to study atmospheric flux of nitrate to land surface/ecosystems. |
X Demographics
The data shown below were collected from the profiles of 9 X users who shared this research output. Click here to find out more about how the information was compiled.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| United States | 4 | 44% |
| United Kingdom | 1 | 11% |
| Unknown | 4 | 44% |
Demographic breakdown
| Type | Count | As % |
|---|---|---|
| Members of the public | 6 | 67% |
| Scientists | 2 | 22% |
| Science communicators (journalists, bloggers, editors) | 1 | 11% |
Mendeley readers
The data shown below were compiled from readership statistics for 139 Mendeley readers of this research output. Click here to see the associated Mendeley record.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Germany | 2 | 1% |
| United States | 2 | 1% |
| Canada | 1 | <1% |
| India | 1 | <1% |
| Japan | 1 | <1% |
| China | 1 | <1% |
| Unknown | 131 | 94% |
Demographic breakdown
| Readers by professional status | Count | As % |
|---|---|---|
| Researcher | 28 | 20% |
| Student > Ph. D. Student | 25 | 18% |
| Student > Master | 15 | 11% |
| Student > Bachelor | 15 | 11% |
| Professor | 11 | 8% |
| Other | 26 | 19% |
| Unknown | 19 | 14% |
| Readers by discipline | Count | As % |
|---|---|---|
| Earth and Planetary Sciences | 47 | 34% |
| Environmental Science | 35 | 25% |
| Agricultural and Biological Sciences | 11 | 8% |
| Chemistry | 9 | 6% |
| Social Sciences | 3 | 2% |
| Other | 11 | 8% |
| Unknown | 23 | 17% |
Attention Score in Context
This research output has an Altmetric Attention Score of 109. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 28 April 2014.
All research outputs
#377,479
of 25,109,675 outputs
Outputs from Proceedings of the National Academy of Sciences of the United States of America
#6,832
of 102,382 outputs
Outputs of similar age
#3,186
of 233,935 outputs
Outputs of similar age from Proceedings of the National Academy of Sciences of the United States of America
#109
of 1,002 outputs
Altmetric has tracked 25,109,675 research outputs across all sources so far. Compared to these this one has done particularly well and is in the 98th percentile: it's in the top 5% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 102,382 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 39.1. This one has done particularly well, scoring higher than 93% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 233,935 tracked outputs that were published within six weeks on either side of this one in any source. This one has done particularly well, scoring higher than 98% of its contemporaries.
We're also able to compare this research output to 1,002 others from the same source and published within six weeks on either side of this one. This one has done well, scoring higher than 89% of its contemporaries.