Dataset Information

Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change.

ABSTRACT: Nitrogen stable isotope ratio (?(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 ?(15)N and major ions (e.g., NO3(-), SO4(2-)) over the last ?200 y show that the decrease in ?(15)N is not always associated with increasing NO3(-) concentrations, and the decreasing trend actually leveled off ?1970. Correlation of ?(15)N with H(+), NO3(-), and HNO3 concentrations, combined with nitrogen isotope fractionation models, suggests that the ?(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 ?(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 ?(15)N of nitrate and should be considered when using ?(15)N as a source indicator to study atmospheric flux of nitrate to land surface/ecosystems.

SUBMITTER: Geng L

PROVIDER: S-EPMC4000786 | biostudies-other | 2014 Apr

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change.

Geng Lei L Alexander Becky B Cole-Dai Jihong J Steig Eric J EJ Savarino Joël J Sofen Eric D ED Schauer Andrew J AJ

Proceedings of the National Academy of Sciences of the United States of America 20140407 16

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 ∼20 ...[more]

PMID: 24711383

Similar Datasets

Project description:The Chesapeake Bay watershed has been the focus of pioneering studies of the role of atmospheric nitrogen (N) deposition as a nutrient source and driver of estuarine trophic status. Here, we review the history and evolution of scientific investigations of the role of atmospheric N deposition, examine trends from wet and dry deposition networks, and present century-long (1950-2050) atmospheric N deposition estimates. Early investigations demonstrated the importance of atmospheric deposition as an N source to the Bay, providing 25%-40% among all major N sources. These early studies led to the unprecedented inclusion of targeted decreases in atmospheric N deposition as part of the multi-stakeholder effort to reduce N loads to the Bay. Emissions of nitrogen oxides (NOx) and deposition of wet nitrate, oxidized dry N, and dry ammonium (NH4+) sharply and synchronously declined by 60%-73% during 1995-2019. These decreases largely resulted from implementation of Title IV of the 1990 Clean Air Act Amendments, which began in 1995. Wet NH4+ deposition shows no significant trend during this period. The century-long atmospheric N deposition estimates indicate an increase in total atmospheric N deposition in the Chesapeake watershed from 1950 to a peak of ~15 kg N/ha/yr in 1979, trailed by a slight decline of <10% through the mid-1990s, and followed by a sharp decline of about 40% thereafter through 2019. An additional 21% decline in atmospheric N deposition is projected from 2015 to 2050. A comparison of the Potomac River and James River watersheds indicates higher atmospheric N deposition in the Potomac, likely resulting from greater emissions from higher proportions of agricultural and urban land in this basin. Atmospheric N deposition rose from 30% among all N sources to the Chesapeake Bay watershed in 1950 to a peak of 40% in 1973, and a decline to 28% by 2015. These data highlight the important role of atmospheric N deposition in the Chesapeake Bay watershed and present a potential opportunity for decreases in deposition to contribute to further reducing N loads and improving the trophic status of tidal waters.

Dataset Information

Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change.

Publications

Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets