Increased global nitrous oxide emissions from streams and rivers in the Anthropocene

Yao, Yuanzhi; Tian, Hanqin; Shi, Hao; Pan, Shufen; Xu, Rongting; Pan, Naiqing; Canadell, Josep G.

doi:10.1038/s41558-019-0665-8

Cited by 167 publications

(191 citation statements)

References 41 publications

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“…Previous studies have shown that N deposition could degrade aquatic ecosystems and human health and increase GHG emissions (Goulding et al, 1998; Xu et al, 2018, 2019; Yao et al, 2020). In this study, N deposition accounted for 8% of N 2 O emissions over the contemporary period.…”

Section: Discussionmentioning

confidence: 99%

Global N₂O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis

Tian

Pan

et al. 2020

Global Biogeochemical Cycles

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Human activities have caused considerable perturbations of the nitrogen (N) cycle, leading to a~20% increase in the concentration of atmospheric nitrous oxide (N 2 O) since the preindustrial era. While substantial efforts have been made to quantify global and regional N 2 O emissions from cropland, there is large uncertainty regarding how climate change and variability have altered net N 2 O fluxes at annual and decadal time scales. Herein, we applied a process-based dynamic land ecosystem model (DLEM) to estimate global N 2 O emissions from cropland driven by synthetic N fertilizer application and multiple environmental factors (i.e., elevated CO 2 , atmospheric N deposition, and climate change). We estimate that global cropland N 2 O emissions increased by 180% (from 1.1 ± 0.2 to 3.3 ± 0.1 Tg N year −1 ; mean ±1 standard deviation) during 1961-2014. Synthetic N fertilizer applications accounted for~70% of total emissions during 2000-2014. At the regional scale, Europe and North America were two leading regions for N 2 O emissions in the 1960s. However, East Asia became the largest emitter after the 1990s. Compared with estimates based on linear and nonlinear emission factors, our results were 150% and 186% larger, respectively, at the global scale during 2000-2014. Our higher estimates of N 2 O emissions could be attributable to the legacy effect from previous N addition to cropland as well as the interactive effect of N addition and climate change. To reduce future cropland N 2 O emissions, effective mitigation strategies should be implemented in regions that have received high levels of N fertilizer and regions that would be more vulnerable to future climate change.

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Section: Discussionmentioning

confidence: 99%

Global N₂O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis

Tian

Pan

et al. 2020

Global Biogeochemical Cycles

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“…River networks regulate biogeochemical fluxes from continents to the oceans [1][2][3] and to the atmosphere [4][5][6][7][8][9] , influencing water quality, coastal dead zones, food webs, and greenhouse gas emissions. For example, at a continental scale, inland waters return ~25% of net carbon uptake by terrestrial ecosystems back to the atmosphere 10 .…”

Section: Main Textmentioning

confidence: 99%

Superlinear scaling of riverine biogeochemical function with watershed size

Wollheim

Harms

Robison

et al. 2021

Preprint

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River networks are a crucial component of the earth system because they regulate carbon and nutrient exchange between continents, the atmosphere, and oceans. Quantifying the role of river networks at broad spatial scales must accommodate spatial heterogeneity, discharge variability, and upstream-downstream connectivity. Allometric scaling relationships of cumulative biogeochemical function with watershed size integrate these factors, providing an approach for understanding the role of fluvial networks in the earth system. Here we demonstrate that allometric scaling relationships of cumulative river network function are linear (power exponent ~ 1) when biogeochemical reactivity is high and river discharges are low, but become increasingly superlinear (power exponent > 1) as reactivity declines or discharge increases. Superlinear scaling indicates that biogeochemical function of entire river networks within a watershed is an emergent property that increases disproportionately with increasing watershed size. Expanding observation networks will increase precision in riverine fluxes of carbon and nutrients estimated by allometric scaling functions.

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“…Ponds and streams had the largest combined emission intensity of CH 4 and N 2 O across non-marine waters, while estuaries acted as the smallest potential aquatic emitter to the atmosphere. These results indicated that small water bodies (i.e., ponds or streams) with a high surface-area-to-volume ratio and shallow depth likely play a greater role in controlling land-atmosphere uxes than are currently represented in global C budget13,24 .Global CH 4 and N 2 O emissions from non-marine watersBottom-up approaches are typically used to estimate global and regional CH 4 and N 2 O emissions from inland waters, such as the data-driven approaches and extrapolations9 . Based on area-scaled emission rates, we estimated global CH 4 and N 2 O emissions from four major inland waters (rivers, reservoirs, lakes and streams) and estuaries.…”

mentioning

confidence: 94%

“…Recently, two approaches (top-down vs. bottom-up) have been used to estimate global CH 4 and N 2 O emissions from individual aquatic ecosystems (e.g., rivers, streams or reservoirs), basically showing high spatio-temporal heterogeneity [10][11][12][13] . In general, bottom-up estimates are higher than results obtained from top-down inversion methods.…”

Section: Introductionmentioning

confidence: 99%

Global methane and nitrous oxide emissions from non-marine waters

Zheng

Xiao

et al. 2021

Preprint

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Non-marine waters (i.e., rivers, reservoirs, lakes, ponds, streams and estuaries) are globally significant emitters of methane (CH4) and nitrous oxide (N2O) to the atmosphere, while global estimates of these emissions have been hampered due to the lack of a worldwide comprehensive database with the collection of complete CH4 and N2O flux components. Here we synthesize 2997 in-situ flux or concentration measurements of CH4 and N2O from 277 peer-reviewed publications to examine the role of non-marine waters in shaping climate change. Here we estimate that inland waters including rivers, reservoirs, lakes and streams together release 94.49 Tg CH4 yr− 1 (ebullition plus diffusion) and 1.52 Tg N2O yr− 1 (diffusion) to the atmosphere, yielding an overall CO2-equivalent emission total of 3.05 Pg CO2 yr− 1, representing roughly 59% of CO2 emissions (5.13 Pg CO2 yr− 1) from these four aquatic ecosystems, with lakes acting as the largest emitter for both trace gases. Ebullition is noticed as a dominant flux component, contributing up to 62–84% of total CH4 fluxes across all inland waters. Chamber-derived CH4 flux rates are significantly greater than those determined by diffusion model-based methods for commonly capturing of both diffusive and ebullitive fluxes. The synthesis of global N2O measurements projected that rivers exhibit the highest indirect N2O emission factor (EF5, 0.028%), while streams have the lowest EF5 value (0.015%). Our study reveals a major oversight in regional and global CH4 budgets from inland waters, caused by neglect of the dominant role of ebullition pathways in those emissions. The indirect EF5 values established in this study generally suggest an order of magnitude downward revision is required in current IPCC default EF5 values for inland waters and estuaries. Our findings further indicate that a comprehensive understanding of the magnitude and patterns of CH4 and N2O emissions from non-marine waters is essential in defining the way that these natural ecosystems shape our climate.

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Increased global nitrous oxide emissions from streams and rivers in the Anthropocene

Cited by 167 publications

References 41 publications

Global N₂O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis

Global N₂O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis

Superlinear scaling of riverine biogeochemical function with watershed size

Global methane and nitrous oxide emissions from non-marine waters

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Increased global nitrous oxide emissions from streams and rivers in the Anthropocene

Cited by 167 publications

References 41 publications

Global N2O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis

Global N2O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis

Superlinear scaling of riverine biogeochemical function with watershed size

Global methane and nitrous oxide emissions from non-marine waters

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Global N₂O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis

Global N₂O Emissions From Cropland Driven by Nitrogen Addition and Environmental Factors: Comparison and Uncertainty Analysis