1
|
Maji K, Li Z, Vaidyanathan A, Hu Y, Stowell JD, Milando C, Wellenius G, Kinney PL, Russell AG, Odman MT. Estimated Impacts of Prescribed Fires on Air Quality and Premature Deaths in Georgia and Surrounding Areas in the US, 2015-2020. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:12343-12355. [PMID: 38943591 PMCID: PMC11256750 DOI: 10.1021/acs.est.4c00890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 06/17/2024] [Accepted: 06/20/2024] [Indexed: 07/01/2024]
Abstract
Smoke from wildfires poses a substantial threat to health in communities near and far. To mitigate the extent and potential damage of wildfires, prescribed burning techniques are commonly employed as land management tools; however, they introduce their own smoke-related risks. This study investigates the impact of prescribed fires on daily average PM2.5 and maximum daily 8-h averaged O3 (MDA8-O3) concentrations and estimates premature deaths associated with short-term exposure to prescribed fire PM2.5 and MDA8-O3 in Georgia and surrounding areas of the Southeastern US from 2015 to 2020. Our findings indicate that over the study domain, prescribed fire contributes to average daily PM2.5 by 0.94 ± 1.45 μg/m3 (mean ± standard deviation), accounting for 14.0% of year-round ambient PM2.5. Higher average daily contributions were predicted during the extensive burning season (January-April): 1.43 ± 1.97 μg/m3 (20.0% of ambient PM2.5). Additionally, prescribed burning is also responsible for an annual average increase of 0.36 ± 0.61 ppb in MDA8-O3 (approximately 0.8% of ambient MDA8-O3) and 1.3% (0.62 ± 0.88 ppb) during the extensive burning season. We estimate that short-term exposure to prescribed fire PM2.5 and MDA8-O3 could have caused 2665 (95% confidence interval (CI): 2249-3080) and 233 (95% CI: 148-317) excess deaths, respectively. These results suggest that smoke from prescribed burns increases the mortality. However, refraining from such burns may escalate the risk of wildfires; therefore, the trade-offs between the health impacts of wildfires and prescribed fires, including morbidity, need to be taken into consideration in future studies.
Collapse
Affiliation(s)
- Kamal
J. Maji
- School
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Zongrun Li
- School
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Ambarish Vaidyanathan
- School
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- National
Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30329, United States
| | - Yongtao Hu
- School
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Jennifer D. Stowell
- School
of Public Health, Boston University, Boston, Massachusetts 02118, United States
| | - Chad Milando
- School
of Public Health, Boston University, Boston, Massachusetts 02118, United States
| | - Gregory Wellenius
- School
of Public Health, Boston University, Boston, Massachusetts 02118, United States
| | - Patrick L. Kinney
- School
of Public Health, Boston University, Boston, Massachusetts 02118, United States
| | - Armistead G. Russell
- School
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - M. Talat Odman
- School
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| |
Collapse
|
2
|
Zhu Z, Ma Y, Tigabu M, Wang G, Yi Z, Guo F. Effects of forest fire smoke deposition on soil physico-chemical properties and bacterial community. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 909:168592. [PMID: 37972773 DOI: 10.1016/j.scitotenv.2023.168592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/09/2023] [Accepted: 11/13/2023] [Indexed: 11/19/2023]
Abstract
The number of forest fires has increased globally, together with considerable smoke emission that significantly impacts the atmospheric environment and associated ecosystems. Most current studies have focused on the in situ effects of fire on the forest ecosystem. However, the mechanisms by which smoke particles affect adjacent ecosystems are largely unexplored. In this study, a simulated forest fire combustion system was developed to evaluate the effect of different smoke concentrations (control, low and high) on soil physico-chemical properties of adjacent farmland at two soil depths. The abundance and diversity of bacterial community were also determined. The results showed that smoke deposition increased the contents of total carbon (TC), total nitrogen (TN), and total phosphorus (TP) in the 0-10 cm soil layer; however, no significant changes in soil water content (SWC) and pH values was observed. The ACE(Abundance Coverage-based Fastimator) and Chao1 diversity indices of bacterial community generally showed a downward trend whereas the PD_whole_ tree diversity index increased after 180 d of smoke deposition. The relative abundance of Proteobacteria remained stable, while abundance of Firmicutes in soil decreased after 180 d of smoke deposition. Smoke deposition slightly affected the physical and chemical properties of the 10-20 cm soil, but the range of variation of the relative abundance and diversity dominant bacteria exceeded that of the 0-10 cm soil. A significant positive correlation was found between the soil properties and the alpha diversity indices during the first 30 d after smoke deposition; the correlation then decreased gradually. Redundancy analysis revealed that Proteobacteria, Firmicutes, and Actinobacteria were generally positively correlated with TC, TN, and SWC. As a whole, the study reveals that the effects of smoke deposition on soil physico-chemical properties and bacterial community depends on smoke concentration where relatively low concentration appears to be beneficial to soil bacterial community.
Collapse
Affiliation(s)
- Zhongpan Zhu
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Key Laboratory of State Forestry and Grassland Administration on Soil and Water Conservation of Red Soil Region in Southern China, Fuzhou 350002, China
| | - Yuanfan Ma
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Key Laboratory of State Forestry and Grassland Administration on Soil and Water Conservation of Red Soil Region in Southern China, Fuzhou 350002, China
| | - Mulualem Tigabu
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Guangyu Wang
- Department of Forest Resources Management, Faculty of Forestry, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Zhigang Yi
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Futao Guo
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Key Laboratory of State Forestry and Grassland Administration on Soil and Water Conservation of Red Soil Region in Southern China, Fuzhou 350002, China.
| |
Collapse
|
3
|
Paul MJ, LeDuc SD, Boaggio K, Herrick JD, Kaylor SD, Lassiter MG, Nolte CG, Rice RB. Effects of Air Pollutants from Wildfires on Downwind Ecosystems: Observations, Knowledge Gaps, and Questions for Assessing Risk. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:14787-14796. [PMID: 37769297 DOI: 10.1021/acs.est.2c09061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Wildfires have increased in frequency and area burned, trends expected to continue with climate change. Among other effects, fires release pollutants into the atmosphere, representing a risk to human health and downwind terrestrial and aquatic ecosystems. While human health risks are well studied, the ecological impacts to downwind ecosystems are not, and this gap may present a constraint on developing an adequate assessment of the ecological risks associated with downwind wildfire exposure. Here, we first screened the scientific literature to assess general knowledge about pathways and end points of a conceptual model linking wildfire generated pollutants and other materials to downwind ecosystems. We found a substantial body of literature on the composition of wildfire derived pollution and materials in the atmosphere and subsequent transport, yet little observational or experimental work on their effects on downwind ecological end points. This dearth of information raises many questions related to adequately assessing the ecological risk of downwind exposure, especially given increasing wildfire trends. To guide future research, we pose eight questions within the well-established US EPA ecological risk assessment paradigm that if answered would greatly improve ecological risk assessment and, ultimately, management strategies needed to reduce potential wildfire impacts.
Collapse
Affiliation(s)
- Michael J Paul
- Tetra Tech Inc., PO Box 14409, Durham, North Carolina 27709 United States
| | - Stephen D LeDuc
- United States Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711 United States
| | - Katie Boaggio
- United States Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711 United States
| | - Jeffrey D Herrick
- United States Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711 United States
| | - S Douglas Kaylor
- United States Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711 United States
| | - Meredith G Lassiter
- United States Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711 United States
| | - Christopher G Nolte
- United States Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711 United States
| | - R Byron Rice
- United States Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Drive, Research Triangle Park, North Carolina 27711 United States
| |
Collapse
|
4
|
Olson NE, Boaggio KL, Rice RB, Foley KM, LeDuc SD. Wildfires in the western United States are mobilizing PM 2.5-associated nutrients and may be contributing to downwind cyanobacteria blooms. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:1049-1066. [PMID: 37232758 PMCID: PMC10585592 DOI: 10.1039/d3em00042g] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Wildfire activity is increasing in the continental U.S. and can be linked to climate change effects, including rising temperatures and more frequent drought conditions. Wildfire emissions and large fire frequency have increased in the western U.S., impacting human health and ecosystems. We linked 15 years (2006-2020) of particulate matter (PM2.5) chemical speciation data with smoke plume analysis to identify PM2.5-associated nutrients elevated in air samples on smoke-impacted days. Most macro- and micro-nutrients analyzed (phosphorus, calcium, potassium, sodium, silicon, aluminum, iron, manganese, and magnesium) were significantly elevated on smoke days across all years analyzed. The largest percent increase was observed for phosphorus. With the exception of ammonium, all other nutrients (nitrate, copper, and zinc), although not statistically significant, had higher median values across all years on smoke vs. non-smoke days. Not surprisingly, there was high variation between smoke impacted days, with some nutrients episodically elevated >10 000% during select fire events. Beyond nutrients, we also explored instances where algal blooms occurred in multiple lakes downwind from high-nutrient fires. In these cases, remotely sensed cyanobacteria indices in downwind lakes increased two to seven days following the occurrence of wildfire smoke above the lake. This suggests that elevated nutrients in wildfire smoke may contribute to downwind algal blooms. Since cyanobacteria blooms can be associated with the production of cyanotoxins and wildfire activity is increasing due to climate change, this finding has implications for drinking water reservoirs in the western United States, and for lake ecology, particularly alpine lakes with otherwise limited nutrient inputs.
Collapse
Affiliation(s)
- Nicole E Olson
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA.
| | - Katie L Boaggio
- U.S. Environmental Protection Agency, Office of Air and Radiation, Research Triangle Park, NC, USA
| | - R Byron Rice
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA.
| | - Kristen M Foley
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA.
| | - Stephen D LeDuc
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA.
| |
Collapse
|
5
|
Chang CT, Yang CJ, Huang JC. Wet depositions of cations in forests across NADP, EMEP, and EANET monitoring networks over the last two decades. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:26791-26806. [PMID: 36371567 PMCID: PMC9995420 DOI: 10.1007/s11356-022-24129-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
Studies focused on emissions and acid deposition of sulfur (S) and nitrogen (N) and the consequent precipitation acidity have a long history. However, atmospheric depositions of cations play a critical role in buffering precipitation acidity, and providing cationic nutrients for vegetation growth lacks sufficient studies equally. The spatiotemporal patterns of cation depositions and their neutralization potential across broad scales remain unclear. Through synthesizing the long-term data in forest sites (n = 128) derived from three monitoring networks (NADP in Northern America, EMEP in Europe, and EANET in East Asia) on wet deposition of cations (Na+, NH4-N, K+, Mg2+, and Ca2+), this study assesses the temporal changes and spatial patterns of cation depositions and their neutralization potential over the last two decades. The results showed that the depositions of cationic nutrients were considerably higher in EANET compared to NADP and EMEP. The depositions of sea salt-associated sodium exhibited a significant transition from marine (> 15 kg ha-1 year-1) to inland (< 3.0 kg ha-1 year-1) forest sites attributable to the precipitation quantity and influences of sea spray. The higher emissions of NH3 and particulate matter in East Asia explained the higher cation depositions in EANET than NADP and EMEP. The annual trends of cations revealed that only 20-30% of the forest sites showed significant changing trends and the sites widely spread across the three networks. Possibly, base cation (BC) deposition has reached a low and stable condition in NADP and EMEP, while it has high spatial heterogeneity in the temporal change in EANET. The difference in BC deposition among the three networks reflects their distinct development of economy. Our synthesis indicates that the annual trends of neutralization factor (NF) in NADP can be explained by the declining of acid potential (AP), not by neutralization potential (NP) as BC deposition has been stably low over the past two decades. Whereas, the concurrent decreases of AP and NP in EMEP or plateau period of both AP and NP in EANET have come to a standstill of acid neutralizing capacity.
Collapse
Affiliation(s)
- Chung-Te Chang
- Taiwan International Graduate Program (TIGP) - Ph.D. Program on Biodiversity, Tunghai University, Taichung, 407224, Taiwan.
- Department of Life Science, Tunghai University, Taichung, 407224, Taiwan.
| | - Ci-Jian Yang
- German Research Centre for Geosciences (GFZ), 14473, Potsdam, Germany
| | - Jr-Chuan Huang
- Department of Geography, National Taiwan University, Taipei, 10617, Taiwan
| |
Collapse
|
6
|
Felix JD, Berner A, Wetherbee GA, Murphy SF, Heindel RC. Nitrogen isotopes indicate vehicle emissions and biomass burning dominate ambient ammonia across Colorado's Front Range urban corridor. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 316:120537. [PMID: 36332707 DOI: 10.1016/j.envpol.2022.120537] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/23/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Urban ammonia (NH3) emissions contribute to poor local air quality and can be transported to rural landscapes, impacting sensitive ecosystems. The Colorado Front Range urban corridor encompasses the Denver Metropolitan Area, rural farmland/rangeland and montane forest between the city and the Rocky Mountains. Reactive nitrogen emissions from the corridor are partly responsible for increased N deposition to the wildland-urban interface (WUI) in this region. To determine the significance of individual NH3 sources to WUI ecosystems, we measured the concentration and isotopic composition (δ15N-NH3) of ambient NH3(g) from April to October 2018 across a five-site urban to rural gradient in the corridor. The urban sites had higher NH3 concentrations and δ15N-NH3 values than the rural/suburban sites. Based on isotope mixing models, NH3 emission source contributions for all sites were fertilizer (12 ± 5.7%), livestock waste (18 ± 12%), vehicles (37 ± 23%), and biomass burning (34 ± 20%). Vehicle contributions were consistent across all months with an average of 35% and summer months showed a peak in biomass burning contributions (40%). As wildfires are projected to increase due to climate change, we stress a need for constraints on the isotopic signature of NH3 emitted from wildfires. Vehicle emissions contributed the greatest amount of NH3 (40%) at the urban sites while rural/suburban sites had higher agricultural contributions (41%). Had 2018 not had an anomalously high wildfire season, 46% and 60% of the NH3 would have been attributed to vehicle emissions at the WUI site and urban sites, respectively. NH3 emissions have historically been ascribed to agricultural activities but these findings illustrate the universal significance of vehicle emissions and the potential for sustained wildfire activity to be a primary contributor to NH3. Air quality (e.g., particulate matter) and nitrogen deposition reduction plans may benefit by including management practices that address vehicle NH3 emissions.
Collapse
Affiliation(s)
- J David Felix
- Physical and Environmental Sciences Department; Center for Water Supply Studies, Texas A&M University, Corpus Christi, USA.
| | - Alexander Berner
- Physical and Environmental Sciences Department; Center for Water Supply Studies, Texas A&M University, Corpus Christi, USA
| | | | | | - Ruth C Heindel
- Environmental Studies Program, Kenyon College, Gambier, OH, USA
| |
Collapse
|
7
|
Boaggio K, LeDuc SD, Rice B, Duffney P, Foley KM, Holder A, McDow S, Weaver CP. Beyond Particulate Matter Mass: Heightened Levels of Lead and Other Pollutants Associated with Destructive Fire Events in California. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:14272-14283. [PMID: 36191257 PMCID: PMC10111611 DOI: 10.1021/acs.est.2c02099] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
As the climate warms, wildfire activity is increasing, posing a risk to human health. Studies have reported on particulate matter (PM) in wildfire smoke, yet the chemicals associated with PM have received considerably less attention. Here, we analyzed 13 years (2006-2018) of PM2.5 chemical composition data from monitors in California on smoke-impacted days. Select chemicals (e.g., aluminum and sulfate) were statistically elevated on smoke-impacted days in over half of the years studied. Other chemicals, mostly trace metals harmful to human health (e.g., copper and lead), were elevated during particular fires only. For instance, in 2018, lead was more than 40 times higher on smoke days on average at the Point Reyes monitoring station, due mostly to the Camp Fire, burning approximately 200 km away. There was an association between these metals and the combustion of anthropogenic material (e.g., the burning of houses and vehicles). Although still currently rare, these infrastructure fires are likely becoming more common and can mobilize trace metals in smoke far downwind, at levels generally unseen except in the most polluted areas of the country. We hope a better understanding of the chemicals in wildfire smoke will assist in the communication and reduction of public health risks.
Collapse
Affiliation(s)
- Katie Boaggio
- ORISE Participant at the U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| | - Stephen D. LeDuc
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| | - Byron Rice
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| | - Parker Duffney
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| | - Kristen M. Foley
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| | - Amara Holder
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| | - Stephen McDow
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| | - Christopher P. Weaver
- U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina, 27709, USA
| |
Collapse
|
8
|
Campbell PC, Tong D, Saylor R, Li Y, Ma S, Zhang X, Kondragunta S, Li F. Pronounced increases in nitrogen emissions and deposition due to the historic 2020 wildfires in the western U.S. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 839:156130. [PMID: 35609700 DOI: 10.1016/j.scitotenv.2022.156130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 06/15/2023]
Abstract
Wildfire outbreaks can lead to extreme biomass burning (BB) emissions of both oxidized (e.g., nitrogen oxides; NOx = NO+NO2) and reduced form (e.g., ammonia; NH3) nitrogen (N) compounds. High N emissions are major concerns for air quality, atmospheric deposition, and consequential human and ecosystem health impacts. In this study, we use both satellite-based observations and modeling results to quantify the contribution of BB to the total emissions, and approximate the impact on total N deposition in the western U.S. Our results show that during the 2020 wildfire season of August-October, BB contributes significantly to the total emissions, with a satellite-derived fraction of NH3 to the total reactive N emissions (median ~ 40%) in the range of aircraft observations. During the peak of the western August Complex Fires in September, BB contributed to ~55% (for the contiguous U.S.) and ~ 83% (for the western U.S.) of the monthly total NOx and NH3 emissions. Overall, there is good model performance of the George Mason University-Wildfire Forecasting System (GMU-WFS) used in this work. The extreme BB emissions lead to significant contributions to the total N deposition for different ecosystems in California, with an average August - October 2020 relative increase of ~78% (from 7.1 to 12.6 kg ha-1 year-1) in deposition rate to major vegetation types (mixed forests + grasslands/shrublands/savanna) compared to the GMU-WFS simulations without BB emissions. For mixed forest types only, the average N deposition rate increases (from 6.2 to 16.9 kg ha-1 year-1) are even larger at ~173%. Such large N deposition due to extreme BB emissions are much (~6-12 times) larger than low-end critical load thresholds for major vegetation types (e.g., forests at 1.5-3 kg ha-1 year-1), and thus may result in adverse N deposition effects across larger areas of lichen communities found in California's mixed conifer forests.
Collapse
Affiliation(s)
- Patrick C Campbell
- Center for Spatial Information Science and Systems/Cooperative Institute for Satellite Earth System Studies, George Mason University, Fairfax, VA, USA; Office of Air and Radiation, Air Resources Laboratory, National Oceanic and Atmospheric Administration, College Park, MD, USA.
| | - Daniel Tong
- Center for Spatial Information Science and Systems/Cooperative Institute for Satellite Earth System Studies, George Mason University, Fairfax, VA, USA; Department of Atmospheric, Oceanic and Earth Sciences, George Mason University, Fairfax, VA, USA
| | - Rick Saylor
- Office of Air and Radiation, Air Resources Laboratory, National Oceanic and Atmospheric Administration, College Park, MD, USA
| | - Yunyao Li
- Department of Atmospheric, Oceanic and Earth Sciences, George Mason University, Fairfax, VA, USA
| | - Siqi Ma
- Department of Atmospheric, Oceanic and Earth Sciences, George Mason University, Fairfax, VA, USA
| | - Xiaoyang Zhang
- Geospatial Sciences Center of Excellence, Department of Geography & Geospatial Sciences, South Dakota State University, Brookings, SD, USA
| | - Shobha Kondragunta
- NOAA Satellite Meteorology and Climatology Division, NOAA Air Resources Laboratory, College Park, MD, USA
| | - Fangjun Li
- Geospatial Sciences Center of Excellence, Department of Geography & Geospatial Sciences, South Dakota State University, Brookings, SD, USA
| |
Collapse
|
9
|
Lin J, Compton JE, Hill RA, Herlihy A, Sabo RD, Brooks JR, Weber M, Pickard B, Paulsen S, Stoddard JL. Context is Everything: Interacting Inputs and Landscape Characteristics Control Stream Nitrogen. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:7890-7899. [PMID: 34060819 PMCID: PMC8673309 DOI: 10.1021/acs.est.0c07102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
To understand the environmental and anthropogenic drivers of stream nitrogen (N) concentrations across the conterminous US, we combined summer low-flow data from 4997 streams with watershed information across three survey periods (2000-2014) of the US EPA's National Rivers and Streams Assessment. Watershed N inputs explained 51% of the variation in log-transformed stream total N (TN) concentrations. Both N source and input rates influenced stream NO3/TN ratios and N concentrations. Streams dominated by oxidized N forms (NO3/TN ratio > 0.50) were more strongly responsive to the N input rate compared to streams dominated by other N forms. NO3 proportional contribution increased with N inputs, supporting N saturation-enhanced NO3 export to aquatic ecosystems. By combining information about N inputs with climatic and landscape factors, random forest models of stream N concentrations explained 70, 58, and 60% of the spatial variation in stream concentrations of TN, dissolved inorganic N, and total organic N, respectively. The strength and direction of relationships between watershed drivers and stream N concentrations and forms varied with N input intensity. Model results for high N input watersheds not only indicated potential contributions from contaminated groundwater to high stream N concentrations but also the mitigating role of wetlands.
Collapse
Affiliation(s)
- Jiajia Lin
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
- Oak Ridge Institute for Science and Education, Corvallis, OR 97333
| | - Jana E. Compton
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
| | - Ryan A. Hill
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
| | - Alan Herlihy
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
- Oregon State University, Department of Fisheries and Wildlife, Corvallis, OR 97333
| | - Robert D. Sabo
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, HEEAD, Washington, DC 20004
| | - J. Renée Brooks
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
| | - Marc Weber
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
| | | | - Steve Paulsen
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
| | - John L. Stoddard
- US EPA, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR 97333
| |
Collapse
|