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Zhan Y, Yao Z, Groffman PM, Xie J, Wang Y, Li G, Zheng X, Butterbach-Bahl K. Urbanization can accelerate climate change by increasing soil N 2 O emission while reducing CH 4 uptake. GLOBAL CHANGE BIOLOGY 2023; 29:3489-3502. [PMID: 36825371 DOI: 10.1111/gcb.16652] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/30/2023] [Indexed: 05/16/2023]
Abstract
Urban land-use change has the potential to affect local to global biogeochemical carbon (C) and nitrogen (N) cycles and associated greenhouse gas (GHG) fluxes. We conducted a meta-analysis to (1) assess the effects of urbanization-induced land-use conversion on soil nitrous oxide (N2 O) and methane (CH4 ) fluxes, (2) quantify direct N2 O emission factors (EFd ) of fertilized urban soils used, for example, as lawns or forests, and (3) identify the key drivers leading to flux changes associated with urbanization. On average, urbanization increases soil N2 O emissions by 153%, to 3.0 kg N ha-1 year-1 , while rates of soil CH4 uptake are reduced by 50%, to 2.0 kg C ha-1 year-1 . The global mean annual N2 O EFd of fertilized lawns and urban forests is 1.4%, suggesting that urban soils can be regional hotspots of N2 O emissions. On a global basis, conversion of land to urban greenspaces has increased soil N2 O emission by 0.46 Tg N2 O-N year-1 and decreased soil CH4 uptake by 0.58 Tg CH4 -C year-1 . Urbanization driven changes in soil N2 O emission and CH4 uptake are associated with changes in soil properties (bulk density, pH, total N content, and C/N ratio), increased temperature, and management practices, especially fertilizer use. Overall, our meta-analysis shows that urbanization increases soil N2 O emissions and reduces the role of soils as a sink for atmospheric CH4 . These effects can be mitigated by avoiding soil compaction, reducing fertilization of lawns, and by restoring native ecosystems in urban landscapes.
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Affiliation(s)
- Yang Zhan
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Earth Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Zhisheng Yao
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
| | - Peter M Groffman
- Department of Earth and Environmental Sciences, Brooklyn College, Advanced Science Research Center at The Graduate Center, City University of New York, New York, New York, USA
| | - Junfei Xie
- Beijing Institute of Landscape Architecture, Beijing, P.R. China
| | - Yan Wang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Earth Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Guangtao Li
- Ministry of Transport, Tianjin Research Institute for Water Transport Engineering, Tianjin, P.R. China
| | - Xunhua Zheng
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Earth Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Klaus Butterbach-Bahl
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- Institute for Meteorology and Climate Research, Atmospheric Environmental Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany
- Department of Agroecology, Pioneer Center Land-CRAFT, Aarhus University, Aarhus C, Denmark
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Díaz-Álvarez EA, de la Barrera E. Influence of Land Use on the C and N Status of a C 4 Invasive Grass in a Semi-Arid Region: Implications for Biomonitoring. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10050942. [PMID: 34065049 PMCID: PMC8151467 DOI: 10.3390/plants10050942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
Biomonitoring of atmospheric pollution is an increasingly accepted practice. However, most existing biomonitors are usually epiphytic species from mesic environments. This work assessed the suitability of buffelgrass (Cenchrus ciliaris), an invasive C4 grass in northwestern Mexico, as a biomonitor, by means of the spatial distribution of the carbon and nitrogen content and isotopic signatures for grass samples collected from urban, agricultural, and natural areas throughout the state of Sonora. We found the highest tissue carbon content of 45.6% (on a dry weight basis) and highest nitrogen content of 3.31% for buffelgrass from the Yaqui Valley. We also found the lowest δ13C of -15.9‰, and the highest δ15N of 16.7‰ in the same region. In contrast, the lowest carbon and nitrogen content of 39.4 and 1.49% were found for Bahía de Kino and Río Sonora mountains, respectively. The lowest δ15N of 2.18‰ and the highest δ13C of -13.7‰ were measured for two remote locations. These results show the influence that pollutant emissions, including agriculture and transportation, have on elemental and isotopic composition of vegetation. Buffelgrass is most adequate for tracking carbon and nitrogen emissions in arid environments and for determining alterations on nitrogen soil reactions, as a first approximation for saturation.
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Affiliation(s)
- Edison A. Díaz-Álvarez
- Instituto de Investigaciones Forestales, Universidad Veracruzana, Parque Ecológico “El Haya”, Carretera Antigua a Coatepec-Coapexpan, Xalapa, Veracruz 91070, Mexico;
| | - Erick de la Barrera
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Col. Ex-Hacienda de San José del Cerrito, Morelia Michoacán 58190, Mexico
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3
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Timilsina A, Dong W, Luo J, Lindsey S, Wang Y, Hu C. Nitrogen isotopic signatures and fluxes of N 2O in response to land-use change on naturally occurring saline-alkaline soil. Sci Rep 2020; 10:21253. [PMID: 33277591 PMCID: PMC7718238 DOI: 10.1038/s41598-020-78149-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/19/2020] [Indexed: 11/09/2022] Open
Abstract
The conversion of natural grassland to semi-natural or artificial ecosystems is a large-scale land-use change (LUC) commonly occurring to saline–alkaline land. Conversion of natural to artificial ecosystems, with addition of anthropogenic nitrogen (N) fertilizer, influences N availability in the soil that may result in higher N2O emission along with depletion of 15N, while converting from natural to semi-natural the influence may be small. So, this study assesses the impact of LUC on N2O emission and 15N in N2O emitted from naturally occurring saline–alkaline soil when changing from natural grassland (Phragmites australis) to semi-natural [Tamarix chinensis (Tamarix)] and to cropland (Gossypium spp.). The grassland and Tamarix ecosystems were not subject to any management practice, while the cropland received fertilizer and irrigation. Overall, median N2O flux was significantly different among the ecosystems with the highest from the cropland (25.3 N2O-N µg m−2 h−1), intermediate (8.2 N2O-N µg m−2 h−1) from the Tamarix and the lowest (4.0 N2O-N µg m−2 h−1) from the grassland ecosystem. The 15N isotopic signatures in N2O emitted from the soil were also significantly affected by the LUC with more depleted from cropland (− 25.3 ‰) and less depleted from grassland (− 0.18 ‰). Our results suggested that the conversion of native saline–alkaline grassland with low N to Tamarix or cropland is likely to result in increased soil N2O emission and also contributes significantly to the depletion of the 15N in atmospheric N2O, and the contribution of anthropogenic N addition was found more significant than any other processes.
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Affiliation(s)
- Arbindra Timilsina
- Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Soil Ecology, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, 050021, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Wenxu Dong
- Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Soil Ecology, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, 050021, China
| | - Jiafa Luo
- Land and Environment, AgResearch, Hamilton, 3240, New Zealand
| | - Stuart Lindsey
- Land and Environment, AgResearch, Hamilton, 3240, New Zealand
| | - Yuying Wang
- Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Soil Ecology, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, 050021, China
| | - Chunsheng Hu
- Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Soil Ecology, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, 050021, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
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Nemitz E, Vieno M, Carnell E, Fitch A, Steadman C, Cryle P, Holland M, Morton RD, Hall J, Mills G, Hayes F, Dickie I, Carruthers D, Fowler D, Reis S, Jones L. Potential and limitation of air pollution mitigation by vegetation and uncertainties of deposition-based evaluations. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190320. [PMID: 32981438 PMCID: PMC7536036 DOI: 10.1098/rsta.2019.0320] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The potential to capture additional air pollutants by introducing more vegetation or changing existing short vegetation to woodland on first sight provides an attractive route for lowering urban pollution. Here, an atmospheric chemistry and transport model was run with a range of landcover scenarios to quantify pollutant removal by the existing total UK vegetation as well as the UK urban vegetation and to quantify the effect of large-scale urban tree planting on urban air pollution. UK vegetation as a whole reduces area (population)-weighted concentrations significantly, by 10% (9%) for PM2.5, 30% (22%) for SO2, 24% (19%) for NH3 and 15% (13%) for O3, compared with a desert scenario. By contrast, urban vegetation reduces average urban PM2.5 by only approximately 1%. Even large-scale conversion of half of existing open urban greenspace to forest would lower urban PM2.5 by only another 1%, suggesting that the effect on air quality needs to be considered in the context of the wider benefits of urban tree planting, e.g. on physical and mental health. The net benefits of UK vegetation for NO2 are small, and urban tree planting is even forecast to increase urban NO2 and NOx concentrations, due to the chemical interaction with changes in BVOC emissions and O3, but the details depend on tree species selection. By extrapolation, green infrastructure projects focusing on non-greenspace (roadside trees, green walls, roof-top gardens) would have to be implemented at very large scales to match this effect. Downscaling of the results to micro-interventions solely aimed at pollutant removal suggests that their impact is too limited for their cost-benefit analysis to compare favourably with emission abatement measures. Urban vegetation planting is less effective for lowering pollution than measures to reduce emissions at source. The results highlight interactions that cannot be captured if benefits are quantified via deposition models using prescribed concentrations, and emission damage costs. This article is part of a discussion meeting issue 'Air quality, past present and future'.
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Affiliation(s)
- Eiko Nemitz
- UK Centre for Ecology and Hydrology, Penicuik EH26 0QB, UK
- e-mail:
| | - Massimo Vieno
- UK Centre for Ecology and Hydrology, Penicuik EH26 0QB, UK
| | - Edward Carnell
- UK Centre for Ecology and Hydrology, Penicuik EH26 0QB, UK
| | - Alice Fitch
- UK Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK
| | - Claudia Steadman
- School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Philip Cryle
- EFTEC, Economics for the Environment Consultancy, London, UK
| | | | - R. Daniel Morton
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster, UK
| | - Jane Hall
- UK Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK
| | - Gina Mills
- UK Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK
| | - Felicity Hayes
- UK Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK
| | - Ian Dickie
- EFTEC, Economics for the Environment Consultancy, London, UK
| | - David Carruthers
- Cambridge Environmental Research Consultants Ltd (CERC), Cambridge, UK
| | - David Fowler
- UK Centre for Ecology and Hydrology, Penicuik EH26 0QB, UK
| | - Stefan Reis
- UK Centre for Ecology and Hydrology, Penicuik EH26 0QB, UK
- European Centre for Environment and Health, University of Exeter Medical School, Truro, UK
| | - Laurence Jones
- UK Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK
- Department of Geography and Environmental Science, Liverpool Hope University, Liverpool, UK
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Xu HJ, Yang XR, Li S, Xue XM, Chang S, Li H, Singh BK, Su JQ, Zhu YG. Nitrogen inputs are more important than denitrifier abundances in controlling denitrification-derived N 2O emission from both urban and agricultural soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 650:2807-2817. [PMID: 30373058 DOI: 10.1016/j.scitotenv.2018.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/30/2018] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
Cities are increasingly being recognized as important contributors in global warming, for example by increasing atmospheric nitrous oxide (N2O). However, urban ecosystems remain poorly understood due to their functional complexity. Further, few studies have documented the microbial processes governing the N2O emissions from urban soils. Here, a field study was performed to assess in situ N2O emissions in an urban and agricultural soil located in Xiamen, China. The mechanisms underlying the difference in N2O emission patterns in both soils were further explored in an incubation experiment. Field investigations showed that N2O emission (3.5-19.0 μg N2O-N m-2 h-1) from the urban soil was significantly lower than that from the agricultural soil (25.4-18,502.3 μg N2O-N m-2 h-1). Incubation experiments showed that the urban soil initially emitted lower denitrification-derived N2O because of the lower nirS (encoding nitrite reductases) abundances, whereas overall N2O accumulation during the incubation was mainly controlled by the initial nitrate content in soil. Nitrate addition in a short period (5 days) did not change the total bacterial and denitrifier abundances or the soil bacterial community composition, but significantly altered the relative distribution of some key genera capable of denitrification. Although the urban soil exhibited lower N2O emission than its agricultural counterpart in this study, the expanding urban green areas should be taken into account when building N2O emission reduction targets.
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Affiliation(s)
- Hui-Juan Xu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Xiao-Ru Yang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Shun Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Center for Applied Geosciences, University of Tübingen, Tübingen 72074, Germany
| | - Xi-Mei Xue
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Shuai Chang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Hu Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Brajesh K Singh
- Hawkesbury Institute for the Environment, University of Western Sydney, Penrih 2751, New South Wales, Australia; Global Centre for Land-Based Innovation, University of Western Sydney, Penrith 2751, New South Wales, Australia
| | - Jian-Qiang Su
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
| | - Yong-Guan Zhu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; State Key Lab of Urban and Regional Ecology, Research Center for Eco-environmental Sciences, Beijing 100085, China
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6
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Quantifying Urban Bioswale Nitrogen Cycling in the Soil, Gas, and Plant Phases. WATER 2018. [DOI: 10.3390/w10111627] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bioswales are a common feature of urban green infrastructure plans for stormwater management. Despite this fact, the nitrogen (N) cycle in bioswales remains poorly quantified, especially during dry weather in the soil, gas, and plant phases. To quantify the nitrogen cycle across seven bioswale sites located in the Bronx, New York City, we measured rates of ammonium and nitrate production in bioswale soils. We also measured soil nitrous oxide gas emissions and plant foliar nitrogen. We found that all mineralized nitrogen underwent nitrification, indicating that the soils were nitrogen-rich, particularly during summer months when nitrogen cycling rates increase, as indicated by higher levels of ammonium in the soil. In comparison to mineralization (0 to 110 g N m−2 y−1), the amounts of nitrogen uptake by the plants (0 to 5 g N m−2 y−1) and of nitrogen in gas emissions from the soils (1 to 10 g N m−2 y−1) were low, although nitrous oxide gas emissions increased in the summer. The bioswales’ greatest influx of nitrogen was via stormwater (84 to 591 g N m−2 y−1). These findings indicate that bioswale plants receive overabundant nitrogen from stormwater runoff. However, soils currently used for bioswales contain organic matter contributing to the urban nitrogen load. Thus, bioswale designs should use less nitrogen rich soils and minimize fertilization for lower nitrogen runoff.
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Fries AE, Schifman LA, Shuster WD, Townsend-Small A. Street-level emissions of methane and nitrous oxide from the wastewater collection system in Cincinnati, Ohio. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 236:247-256. [PMID: 29414346 PMCID: PMC6537879 DOI: 10.1016/j.envpol.2018.01.076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 01/20/2018] [Accepted: 01/22/2018] [Indexed: 06/08/2023]
Abstract
Recent studies have indicated that urban streets can be hotspots for emissions of methane (CH4) from leaky natural gas lines, particularly in cities with older natural gas distribution systems. The objective of the current study was to determine whether leaking sewer pipes could also be a source of street-level CH4 as well as nitrous oxide (N2O) in Cincinnati, Ohio, a city with a relatively new gas pipeline network. To do this, we measured the carbon (δ13C) and hydrogen (δ2H) stable isotopic composition of CH4 to distinguish between biogenic CH4 from sewer gas and thermogenic CH4 from leaking natural gas pipelines and measured CH4 and N2O flux rates and concentrations at sites from a previous study of street-level CH4 enhancements (77 out of 104 sites) as well as additional sites found through surveying sewer grates and utility manholes (27 out of 104 sites). The average isotopic signatures for δ13C-CH4 and δ2H-CH4 were -48.5‰ ± 6.0‰ and -302‰ ± 142‰. The measured flux rates ranged from 0.0 to 282.5 mg CH4 day-1 and 0.0-14.1 mg N2O day-1 (n = 43). The average CH4 and N2O concentrations measured in our study were 4.0 ± 7.6 ppm and 392 ± 158 ppb, respectively (n = 104). 72% of sites where fluxes were measured were a source of biogenic CH4. Overall, 47% of the sampled sites had biogenic CH4, while only 13% of our sites had solely thermogenic CH4. The other sites were either a source of both biogenic and thermogenic CH4 (13%), and a relatively large portion of sites had an unresolved source (29%). Overall, this survey of emissions across a large urban area indicates that production and emission of biogenic CH4 and N2O is considerable, although CH4 fluxes are lower than those reported for cities with leaky natural gas distribution systems.
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Affiliation(s)
- Anastasia E Fries
- Department of Geology, University of Cincinnati, 500 Geology-Physics Building, 345 Clifton Court, Cincinnati, OH, 45221, USA
| | - Laura A Schifman
- U.S. Environmental Protection Agency, National Risk Management Research Laboratory, 26 W. Martin Luther King Dr., Cincinnati, OH, 45268, USA
| | - William D Shuster
- U.S. Environmental Protection Agency, National Risk Management Research Laboratory, 26 W. Martin Luther King Dr., Cincinnati, OH, 45268, USA
| | - Amy Townsend-Small
- Department of Geology, University of Cincinnati, 500 Geology-Physics Building, 345 Clifton Court, Cincinnati, OH, 45221, USA.
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8
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Herrmann DL, Cadenasso ML. Nitrogen retention and loss in unfertilized lawns across a light gradient. Urban Ecosyst 2017. [DOI: 10.1007/s11252-017-0684-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Smith RM, Kaushal SS, Beaulieu JJ, Pennino MJ, Welty C. Influence of infrastructure on water quality and greenhouse gas dynamics in urban streams. ACTA ACUST UNITED AC 2017; 14. [PMID: 32665782 DOI: 10.5194/bg-14-2831-2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Streams and rivers are significant sources of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) globally, and watershed management can alter greenhouse gas (GHG) emissions from streams. We hypothesized that urban infrastructure significantly alters downstream water quality and contributes to variability in GHG saturation and emissions. We measured gas saturation and estimated emission rates in headwaters of two urban stream networks (Red Run and Dead Run) of the Baltimore Ecosystem Study Long-Term Ecological Research project. We identified four combinations of stormwater and sanitary infrastructure present in these watersheds, including: (1) stream burial, (2) inline stormwater wetlands, (3) riparian/floodplain preservation, and (4) septic systems. We selected two first order catchments in each of these categories and measured GHG concentrations, emissions, and dissolved inorganic and organic carbon (DIC and DOC) and nutrient concentrations biweekly for 1 year. From a water quality perspective, the DOC : NO3 - ratio of streamwater was significantly different across infrastructure categories. Multiple linear regressions including DOC : NO3 - and other variables (dissolved oxygen, DO; total dissolved nitrogen, TDN; and temperature) explained much of the statistical variation in nitrous oxide (N2O, r2 = 0.78), carbon dioxide (CO2, r2 = 0.78) and methane (CH4, r 2 = 0.50) saturation in stream water. We measured N2O saturation ratios, which were among the highest reported in the literature for streams, ranging from 1.1 to 47 across all sites and dates. N2O saturation ratios were highest in streams draining watersheds with septic systems and strongly correlated with TDN. The CO2 saturation ratio was highly correlated with the N2O saturation ratio across all sites and dates, and the CO2 saturation ratio ranged from 1.1 to 73. CH4 was always supersaturated, with saturation ratios ranging from 3.0 to 2157. Longitudinal surveys extending form headwaters to third-order outlets of Red Run and Dead Run took place in spring and fall. Linear regressions of these data yielded significant negative relationships between each gas with increasing watershed size as well as consistent relationships between solutes (TDN or DOC, and DOC : TDN ratio) and gas saturation. Despite a decline in gas saturation between the headwaters and stream outlet, streams remained saturated with GHGs throughout the drainage network, suggesting that urban streams are continuous sources of CO2, CH4, and N2O. Our results suggest that infrastructure decisions can have significant effects on downstream water quality and greenhouse gases, and watershed management strategies may need to consider coupled impacts on urban water and air quality.
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Affiliation(s)
- Rose M Smith
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.,Department of Geology, Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742, USA
| | - Sujay S Kaushal
- Department of Geology, Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742, USA
| | - Jake J Beaulieu
- US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Cincinnati, OH 45220, USA
| | - Michael J Pennino
- US Environmental Protection Agency National Health and Environmental Effects Research Lab, Corvallis, OR 97333, USA.,Department of Chemical, Biochemical, and Environmental Engineering, Center for Urban Environmental Research and Education, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Claire Welty
- Department of Chemical, Biochemical, and Environmental Engineering, Center for Urban Environmental Research and Education, University of Maryland Baltimore County, Baltimore, MD 21250, USA
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Toyoda S, Yoshida N, Koba K. Isotopocule analysis of biologically produced nitrous oxide in various environments. MASS SPECTROMETRY REVIEWS 2017; 36:135-160. [PMID: 25869149 DOI: 10.1002/mas.21459] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 01/13/2015] [Accepted: 01/13/2015] [Indexed: 06/04/2023]
Abstract
Natural abundance ratios of isotopocules, molecules that have the same chemical constitution and configuration, but that only differ in isotope substitution, retain a record of a compound's origin and reactions. A method to measure isotopocule ratios of nitrous oxide (N2 O) has been established by using mass analysis of molecular ions and fragment ions. The method has been applied widely to environmental samples from the atmosphere, ocean, fresh water, soils, and laboratory-simulation experiments. Results show that isotopocule ratios, particularly the 15 N-site preference (difference between isotopocule ratios 14 N15 N16 O/14 N14 N16 O and 15 N14 N16 O/14 N14 N16 O), have a wide range that depends on their production and consumption processes. Observational and laboratory studies of N2 O related to biological processes are reviewed and discussed to elucidate complex material cycles of this trace gas, which causes global warming and stratospheric ozone depletion. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:135-160, 2017.
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Affiliation(s)
- Sakae Toyoda
- Department of Environmental Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
| | - Naohiro Yoshida
- Department of Environmental Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Keisuke Koba
- Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-City, Tokyo 183-8509, Japan
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11
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Snider DM, Venkiteswaran JJ, Schiff SL, Spoelstra J. From the ground up: global nitrous oxide sources are constrained by stable isotope values. PLoS One 2015; 10:e0118954. [PMID: 25811179 PMCID: PMC4374930 DOI: 10.1371/journal.pone.0118954] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 01/08/2015] [Indexed: 11/18/2022] Open
Abstract
Rising concentrations of nitrous oxide (N2O) in the atmosphere are causing widespread concern because this trace gas plays a key role in the destruction of stratospheric ozone and it is a strong greenhouse gas. The successful mitigation of N2O emissions requires a solid understanding of the relative importance of all N2O sources and sinks. Stable isotope ratio measurements (δ15N-N2O and δ18O-N2O), including the intramolecular distribution of 15N (site preference), are one way to track different sources if they are isotopically distinct. ‘Top-down’ isotope mass-balance studies have had limited success balancing the global N2O budget thus far because the isotopic signatures of soil, freshwater, and marine sources are poorly constrained and a comprehensive analysis of global N2O stable isotope measurements has not been done. Here we used a robust analysis of all available in situ measurements to define key global N2O sources. We showed that the marine source is isotopically distinct from soil and freshwater N2O (the continental source). Further, the global average source (sum of all natural and anthropogenic sources) is largely controlled by soils and freshwaters. These findings substantiate past modelling studies that relied on several assumptions about the global N2O cycle. Finally, a two-box-model and a Bayesian isotope mixing model revealed marine and continental N2O sources have relative contributions of 24–26% and 74–76% to the total, respectively. Further, the Bayesian modeling exercise indicated the N2O flux from freshwaters may be much larger than currently thought.
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Affiliation(s)
- David M. Snider
- National Water Research Institute, Canada Centre for Inland Waters, Environment Canada, Burlington, ON, L7R 4A6, Canada
- * E-mail: (DMS); (JJV)
| | - Jason J. Venkiteswaran
- Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
- * E-mail: (DMS); (JJV)
| | - Sherry L. Schiff
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - John Spoelstra
- National Water Research Institute, Canada Centre for Inland Waters, Environment Canada, Burlington, ON, L7R 4A6, Canada
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
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Martinez NG, Bettez ND, Groffman PM. Sources of variation in home lawn soil nitrogen dynamics. JOURNAL OF ENVIRONMENTAL QUALITY 2014; 43:2146-2151. [PMID: 25602231 DOI: 10.2134/jeq2014.03.0103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Urban, suburban, and exurban lawns are an increasingly important ecosystem type in the United States. There is great concern about the environmental performance of lawns, especially nitrate (NO) leaching and nitrous oxide (NO) flux associated with nitrogen (N) fertilizer use. Previous studies of lawn N dynamics have produced conflicting results, with some studies showing high NO leaching and NO flux and others showing lower losses and high retention and cycling of N inputs. We hypothesized that this variation is caused by differences in lawn management and soil properties that control root and soil organic matter (SOM) dynamics that influence N cycling processes. We tested these hypotheses by making measurements of soil NO, root biomass, rates of potential net N mineralization and nitrification, NO flux, and SOM levels in samples from the front and backyards of residential homes in suburban and exurban neighborhoods with contrasting soil types in the Baltimore metropolitan area. There were no differences between front and backyards, between suburban and exurban neighborhoods, or between different soil types. Further, there were no significant relationships between root biomass, SOM, soil NO levels, and NO fluxes. These results suggest that lawns have uniformly high rates of plant productivity that underlies high levels of SOM and N retention in these ecosystems across the Baltimore metropolitan area.
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Urban microbiomes and urban ecology: how do microbes in the built environment affect human sustainability in cities? J Microbiol 2014; 52:721-8. [PMID: 25224504 DOI: 10.1007/s12275-014-4364-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 08/06/2014] [Accepted: 08/06/2014] [Indexed: 12/30/2022]
Abstract
Humans increasingly occupy cities. Globally, about 50% of the total human population lives in urban environments, and in spite of some trends for deurbanization, the transition from rural to urban life is expected to accelerate in the future, especially in developing nations and regions. The Republic of Korea, for example, has witnessed a dramatic rise in its urban population, which now accounts for nearly 90% of all residents; the increase from about 29% in 1955 has been attributed to multiple factors, but has clearly been driven by extraordinary growth in the gross domestic product accompanying industrialization. While industrialization and urbanization have unarguably led to major improvements in quality of life indices in Korea and elsewhere, numerous serious problems have also been acknowledged, including concerns about resource availability, water quality, amplification of global warming and new threats to health. Questions about sustainability have therefore led Koreans and others to consider deurbanization as a management policy. Whether this offers any realistic prospects for a sustainable future remains to be seen. In the interim, it has become increasingly clear that built environments are no less complex than natural environments, and that they depend on a variety of internal and external connections involving microbes and the processes for which microbes are responsible. I provide here a definition of the urban microbiome, and through examples indicate its centrality to human function and wellbeing in urban systems. I also identify important knowledge gaps and unanswered questions about urban microbiomes that must be addressed to develop a robust, predictive and general understanding of urban biology and ecology that can be used to inform policy-making for sustainable systems.
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Grover SPP, Cohan A, Chan HS, Livesley SJ, Beringer J, Daly E. Occasional large emissions of nitrous oxide and methane observed in stormwater biofiltration systems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 465:64-71. [PMID: 23399408 DOI: 10.1016/j.scitotenv.2013.01.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 06/01/2023]
Abstract
Designed, green infrastructures are becoming a customary feature of the urban landscape. Sustainable technologies for stormwater management, and biofilters in particular, are increasingly used to reduce stormwater runoff volumes and peaks as well as improve the water quality of runoff discharged into urban water bodies. Although a lot of research has been devoted to these technologies, their effect in terms of greenhouse gas fluxes in urban areas has not been yet investigated. We present the first study aimed at quantifying greenhouse gas fluxes between the soil of stormwater biofilters and the atmosphere. N2O, CH4, and CO2 were measured periodically over a year in two operational vegetated biofiltration cells at Monash University in Melbourne, Australia. One cell had a saturated zone at the bottom, and compost and hardwood mulch added to the sandy loam filter media. The other cell had no saturated zone and was composed of sandy loam. Similar sedges were planted in both cells. The biofilter soil was a small N2O source and a sink for CH4 for most measurement events, with occasional large emissions of both N2O and CH4 under very wet conditions. Average N2O fluxes from the cell with the saturated zone were almost five-fold greater (65.6 μg N2O-N m(-2) h(-1)) than from the other cell (13.7 μg N2O-N m(-2) h(-1)), with peaks up to 1100 μg N2O-N m(-2) h(-1). These N2O fluxes are of similar magnitude to those measured in other urban soils, but with larger peak emissions. The CH4 sink strength of the cell with the saturated zone (-3.8 μg CH4-C m(-2) h(-1)) was lower than the other cell (-18.3 μg CH4-C m(-2) h(-1)). Both cells of the biofilter appeared to take up CH4 at similar rates to other urban lawn systems; however, the biofilter cells displayed occasional large CH4 emissions following inflow events, which were not seen in other urban systems. CO2 fluxes increased with soil temperature in both cells, and in the cell without the saturated zone CO2 fluxes decreased as soil moisture increased. Other studies of CO2 fluxes from urban soils have found both similar and larger CO2 emissions than those measured in the biofilter. The results of this study suggest that the greenhouse gas footprint of stormwater treatment warrant consideration in the planning and implementation of engineered green infrastructures.
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Affiliation(s)
- Samantha P P Grover
- Department of Civil Engineering, Monash University, Clayton, Victoria, 3800, Australia.
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Durán J, Rodríguez A, Morse JL, Groffman PM. Winter climate change effects on soil C and N cycles in urban grasslands. GLOBAL CHANGE BIOLOGY 2013; 19:2826-2837. [PMID: 23630015 DOI: 10.1111/gcb.12238] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 04/19/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
Despite growing recognition of the role that cities have in global biogeochemical cycles, urban systems are among the least understood of all ecosystems. Urban grasslands are expanding rapidly along with urbanization, which is expected to increase at unprecedented rates in upcoming decades. The large and increasing area of urban grasslands and their impact on water and air quality justify the need for a better understanding of their biogeochemical cycles. There is also great uncertainty about the effect that climate change, especially changes in winter snow cover, will have on nutrient cycles in urban grasslands. We aimed to evaluate how reduced snow accumulation directly affects winter soil frost dynamics, and indirectly greenhouse gas fluxes and the processing of carbon (C) and nitrogen (N) during the subsequent growing season in northern urban grasslands. Both artificial and natural snow reduction increased winter soil frost, affecting winter microbial C and N processing, accelerating C and N cycles and increasing soil : atmosphere greenhouse gas exchange during the subsequent growing season. With lower snow accumulations that are predicted with climate change, we found decreases in N retention in these ecosystems, and increases in N2 O and CO2 flux to the atmosphere, significantly increasing the global warming potential of urban grasslands. Our results suggest that the environmental impacts of these rapidly expanding ecosystems are likely to increase as climate change brings milder winters and more extensive soil frost.
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Affiliation(s)
- Jorge Durán
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
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Wunderlin P, Lehmann MF, Siegrist H, Tuzson B, Joss A, Emmenegger L, Mohn J. Isotope signatures of N₂O in a mixed microbial population system: constraints on N₂O producing pathways in wastewater treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:1339-48. [PMID: 23249174 DOI: 10.1021/es303174x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We present measurements of site preference (SP) and bulk (15)N/(14)N ratios (δ(15)N(bulk)(N2O)) of nitrous oxide (N(2)O) by quantum cascade laser absorption spectroscopy (QCLAS) as a powerful tool to investigate N(2)O production pathways in biological wastewater treatment. QCLAS enables high-precision N(2)O isotopomer analysis in real time. This allowed us to trace short-term fluctuations in SP and δ(15)N(bulk)(N2O) and, hence, microbial transformation pathways during individual batch experiments with activated sludge from a pilot-scale facility treating municipal wastewater. On the basis of previous work with microbial pure cultures, we demonstrate that N(2)O emitted during ammonia (NH(4)(+)) oxidation with a SP of -5.8 to 5.6 ‰ derives mostly from nitrite (NO(2)(-)) reduction (e.g., nitrifier denitrification), with a minor contribution from hydroxylamine (NH(2)OH) oxidation at the beginning of the experiments. SP of N(2)O produced under anoxic conditions was always positive (1.2 to 26.1 ‰), and SP values at the high end of this spectrum (24.9 to 26.1 ‰) are indicative of N(2)O reductase activity. The measured δ(15)N(bulk)(N2O) at the initiation of the NH(4)(+) oxidation experiments ranged between -42.3 and -57.6 ‰ (corresponding to a nitrogen isotope effect Δδ(15)N = δ(15)N(substrate) - δ(15)N(bulk)(N2O) of 43.5 to 58.8 ‰), which is considerably higher than under denitrifying conditions (δ(15)N(bulk)(N2O) 2.4 to -17 ‰; Δδ(15)N = 0.1 to 19.5 ‰). During the course of all NH(4)(+) oxidation and nitrate (NO(3)(-)) reduction experiments, δ(15)N(bulk)(N2O) increased significantly, indicating net (15)N enrichment in the dissolved inorganic nitrogen substrates (NH(4)(+), NO(3)(-)) and transfer into the N(2)O pool. The decrease in δ(15)N(bulk)(N2O) during NO(2)(-) and NH(2)OH oxidation experiments is best explained by inverse fractionation during the oxidation of NO(2)(-) to NO(3)(-).
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Affiliation(s)
- Pascal Wunderlin
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, P.O. Box 611, 8600 Duebendorf, Switzerland.
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Townsend-Small A, Tyler SC, Pataki DE, Xu X, Christensen LE. Isotopic measurements of atmospheric methane in Los Angeles, California, USA: Influence of “fugitive” fossil fuel emissions. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016826] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Raciti SM, Burgin AJ, Groffman PM, Lewis DN, Fahey TJ. Denitrification in suburban lawn soils. JOURNAL OF ENVIRONMENTAL QUALITY 2011; 40:1932-1940. [PMID: 22031577 DOI: 10.2134/jeq2011.0107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
There is great uncertainty about the fate of nitrogen (N) added to urban and suburban lawns. We used direct flux and in situ chamber methods to measure N and NO fluxes from lawns instrumented with soil O sensors. We hypothesized that soil O, moisture, and available NO were the most important controls on denitrification and that N and NO fluxes would be high following fertilizer addition and precipitation events. While our results support these hypotheses, the thresholds of soil O, moisture, and NO availability required to see significant N fluxes were greater than expected. Denitrification rates were high in saturated, fertilized soils, but low under all other conditions. Annual denitrification was calculated to be 14.0 ± 3.6 kg N ha yr, with 5% of the growing season accounting for >80% of the annual activity. Denitrification is thus an important means of removing reactive N in residential landscapes, but varies markedly in space, time, and with factors that affect soil saturation (texture, structure, compaction) and NO availability (fertilization). Rates of in situ NO flux were low; however, when recently fertilized soils saturated with water were incubated in the laboratory, we saw extraordinarily high rates of NO production for the first few hours of incubation, followed by rapid NO consumption later in the experiment. These findings indicate a lag time between accelerated NO production and counterbalancing increases in NO consumption; thus, we cannot yet conclude that lawns are an insignificant source of NO in our study area.
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Affiliation(s)
- Steve M Raciti
- Department of Natural Resources, Cornell University, Ithaca, NY, USA.
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Townsend-Small A, Pataki DE, Tseng LY, Tsai CY, Rosso D. Nitrous oxide emissions from wastewater treatment and water reclamation plants in southern California. JOURNAL OF ENVIRONMENTAL QUALITY 2011; 40:1542-50. [PMID: 21869516 DOI: 10.2134/jeq2011.0059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Nitrous oxide (N₂O) is a long-lived and potent greenhouse gas produced during microbial nitrification and denitrification. In developed countries, centralized water reclamation plants often use these processes for N removal before effluent is used for irrigation or discharged to surface water, thus making this treatment a potentially large source of N₂O in urban areas. In the arid but densely populated southwestern United States, water reclamation for irrigation is an important alternative to long-distance water importation. We measured N₂O concentrations and fluxes from several wastewater treatment processes in urban southern California. We found that N removal during water reclamation may lead to in situ N₂O emission rates that are three or more times greater than traditional treatment processes (C oxidation only). In the water reclamation plants tested, N₂O production was a greater percentage of total N removed (1.2%) than traditional treatment processes (C oxidation only) (0.4%). We also measured stable isotope ratios (δN and δO) of emitted N₂O and found distinct δN signatures of N₂O from denitrification (0.0 ± 4.0 ‰) and nitrification reactors (-24.5 ± 2.2 ‰), respectively. These isotope data confirm that both nitrification and denitrification contribute to N₂O emissions within the same treatment plant. Our estimates indicate that N₂O emissions from biological N removal for water reclamation may be several orders of magnitude greater than N₂O emissions from agricultural activities in highly urbanized southern California. Our results suggest that wastewater treatment that includes biological nitrogen removal can significantly increase urban N₂O emissions.
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