TY - JOUR
T1 - Mixed method approach to assess atmospheric nitrogen deposition in arid and semi-arid ecosystems
AU - Cook, Elizabeth M.
AU - Sponseller, Ryan
AU - Grimm, Nancy
AU - Hall, Sharon
N1 - Funding Information:
We thank Diane Alexander, Stevan Earl, Roy Erickson, Kris Fecteau, David Huber, Cathy Kochert, Jennifer Learned, Yevgeniy Marusenko, Sam Norlin, Brenda Ramierz, Michelle Schmoker Davis, and Quincy Stewart for help with field and laboratory work; Ron Pope for providing local traffic data; and Daniel Henz for providing meteorological data. This work was work supported by the National Science Foundation under grant no. DEB-0423704 , BCS-1026865 , and DEB-1637590 Central Arizona–Phoenix Long-term Ecological Research program and grant no. 0504248 , Integrative Graduate Education Research and Training (IGERT) in Urban Ecology. Appendix A
Funding Information:
We thank Diane Alexander, Stevan Earl, Roy Erickson, Kris Fecteau, David Huber, Cathy Kochert, Jennifer Learned, Yevgeniy Marusenko, Sam Norlin, Brenda Ramierz, Michelle Schmoker Davis, and Quincy Stewart for help with field and laboratory work; Ron Pope for providing local traffic data; and Daniel Henz for providing meteorological data. This work was work supported by the National Science Foundation under grant no. DEB-0423704, BCS-1026865, and DEB-1637590 Central Arizona–Phoenix Long-term Ecological Research program and grant no. 0504248, Integrative Graduate Education Research and Training (IGERT) in Urban Ecology.
Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/8
Y1 - 2018/8
N2 - Arid and semi-arid ecosystems (aridlands) cover a third of Earth's terrestrial surface and contain organisms that are sensitive to low level atmospheric pollutants. Atmospheric nitrogen (N) inputs to aridlands are likely to cause changes in plant community composition, fire frequency, and carbon cycling and storage. However, few studies have documented long-term rates of atmospheric N inputs in aridlands because dry deposition is technically difficult to quantify, and extensive sampling is needed to capture fluxes with spatially and temporally heterogeneous rainfall patterns. Here, we quantified long-term spatial and temporal patterns of inorganic N deposition in protected aridland ecosystems across an extensive urban-rural gradient using multiple sampling methods. We compared long-term rates of N deposition from ion-exchange resin (IER) collectors (bulk and throughfall, 2006-2015), wet-dry bucket collectors (2006-2015), and dry deposition from the inferential method using passive samplers (2010-2012). From mixed approaches with IER collectors and inferential methods, we determined that 7.2 ± 0.4 kgNha−1y−1 is deposited to protected Sonoran Desert within metropolitan Phoenix, Arizona and 6.1 ± 0.3 kgNha−1y−1 in nearby desert ecosystems. Regional scale models overestimated deposition rates for our sampling period by 60% and misidentified hot spots of deposition across the airshed. By contrast, the easy-deployment IER throughfall collectors showed minimal spatial variation across the urban-rural gradient and underestimated deposition fluxes by 54%, largely because of underestimated dry deposition in throughfall. However, seasonal sampling of the IER collectors over 10 years allowed us to capture significant seasonal variation in N deposition and the importance of precipitation timing. These results, derived from the longest, spatially and temporally explicit dataset in drylands, highlight the need for long-term, mixed methods to estimate atmospheric nutrient enrichment to aridlands in a rapidly changing world. Our findings highlight low rates of inorganic nitrogen deposition to protected Sonoran Desert ecosystems, the need for mixed methods, and the importance of season and timing of precipitation as primary drivers of atmospheric nutrient enrichment to aridland systems.
AB - Arid and semi-arid ecosystems (aridlands) cover a third of Earth's terrestrial surface and contain organisms that are sensitive to low level atmospheric pollutants. Atmospheric nitrogen (N) inputs to aridlands are likely to cause changes in plant community composition, fire frequency, and carbon cycling and storage. However, few studies have documented long-term rates of atmospheric N inputs in aridlands because dry deposition is technically difficult to quantify, and extensive sampling is needed to capture fluxes with spatially and temporally heterogeneous rainfall patterns. Here, we quantified long-term spatial and temporal patterns of inorganic N deposition in protected aridland ecosystems across an extensive urban-rural gradient using multiple sampling methods. We compared long-term rates of N deposition from ion-exchange resin (IER) collectors (bulk and throughfall, 2006-2015), wet-dry bucket collectors (2006-2015), and dry deposition from the inferential method using passive samplers (2010-2012). From mixed approaches with IER collectors and inferential methods, we determined that 7.2 ± 0.4 kgNha−1y−1 is deposited to protected Sonoran Desert within metropolitan Phoenix, Arizona and 6.1 ± 0.3 kgNha−1y−1 in nearby desert ecosystems. Regional scale models overestimated deposition rates for our sampling period by 60% and misidentified hot spots of deposition across the airshed. By contrast, the easy-deployment IER throughfall collectors showed minimal spatial variation across the urban-rural gradient and underestimated deposition fluxes by 54%, largely because of underestimated dry deposition in throughfall. However, seasonal sampling of the IER collectors over 10 years allowed us to capture significant seasonal variation in N deposition and the importance of precipitation timing. These results, derived from the longest, spatially and temporally explicit dataset in drylands, highlight the need for long-term, mixed methods to estimate atmospheric nutrient enrichment to aridlands in a rapidly changing world. Our findings highlight low rates of inorganic nitrogen deposition to protected Sonoran Desert ecosystems, the need for mixed methods, and the importance of season and timing of precipitation as primary drivers of atmospheric nutrient enrichment to aridland systems.
KW - Aridland ecosystems
KW - Dry deposition
KW - Inorganic nitrogen deposition
KW - Urban-rural gradient
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U2 - 10.1016/j.envpol.2018.04.013
DO - 10.1016/j.envpol.2018.04.013
M3 - Article
C2 - 29705717
AN - SCOPUS:85046365457
SN - 0269-7491
VL - 239
SP - 617
EP - 630
JO - Environmental Pollution
JF - Environmental Pollution
ER -