Insights of greenhouse gases (CO2, CH4 and N2O) dynamics in sub-tropical estuaries from a coupled hydrodynamic-biogeochemical estuarine model

Coastal waters are typically productive aquatic ecosystems and play an important role in the global greenhouse gas (GHG) budget. However, the uncertainty in the estimation of GHG emission from estuaries remains large due to significant variability in GHG concentrations in time and space. This study aimed to provide a more accurate estimation of GHG emissions from sub-tropical estuaries by validating and analyzing results from a 3D hydrodynamic-biogeochemical model used to capture the temporal and spatial dynamics of the major GHG (CO2 CH4, and N2O). The model was applied to the Brisbane, Maroochy, and Noosa Estuary in Queensland, Australia, representing systems under high, median, and low human impacts, and was validated with datasets from long-term monitoring stations and field campaigns along the freshwater-marine continuum. Distinct spatial heterogeneity of GHG distribution was found with the upstream acting as a hotspot for emission to the atmosphere, despite this area occupying a relatively small portion of the rivers. Seasonal variations of pCO2 at the surface were driven mostly by the changes in water temperature and DIC concentrations, while strong diurnal variation was also found, driven by the changes related to tidal forcing. All GHG showed distinct signatures in the three rivers, related to trophic statues and hydrology. The model allowed us to approximate the fraction of incoming carbon and nitrogen that was lost to the atmosphere as GHG emissions, which is a step towards improving regional and national GHG budgets. A link of the biogeochemical model to a parameter optimization software PEST is being used to assist in uncertainty analysis from the model outputs.

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Greenhouse gas emissions from fen soils used for forage production in northern Germany

Biogeosciences ◽

10.5194/bg-13-5221-2016 ◽

2016 ◽

Vol 13 (18) ◽

pp. 5221-5244 ◽

Cited By ~ 15

Author(s):

Arne Poyda ◽

Thorsten Reinsch ◽

Christof Kluß ◽

Ralf Loges ◽

Friedhelm Taube

Keyword(s):

Ghg Emissions ◽

Farming Systems ◽

Forage Yield ◽

N2o Emissions ◽

Net Energy ◽

Forage Production ◽

Climatic Impact ◽

Northern Germany ◽

Ch4 And N2o

Abstract. A large share of peatlands in northwestern Germany is drained for agricultural purposes, thereby emitting high amounts of greenhouse gases (GHGs). In order to quantify the climatic impact of fen soils in dairy farming systems of northern Germany, GHG exchange and forage yield were determined on four experimental sites which differed in terms of management and drainage intensity: (a) rewetted and unutilized grassland (UG), (b) intensive and wet grassland (GW), (c) intensive and moist grassland (GM) and (d) arable forage cropping (AR). Net ecosystem exchange (NEE) of CO2 and fluxes of CH4 and N2O were measured using closed manual chambers. CH4 fluxes were significantly affected by groundwater level (GWL) and soil temperature, whereas N2O fluxes showed a significant relation to the amount of nitrate in top soil. Annual balances of all three gases, as well as the global warming potential (GWP), were significantly correlated to mean annual GWL. A 2-year mean GWP, combined from CO2–C eq. of NEE, CH4 and N2O emissions, as well as C input (slurry) and C output (harvest), was 3.8, 11.7, 17.7 and 17.3 Mg CO2–C eq. ha−1 a−1 for sites UG, GW, GM and AR, respectively (standard error (SE) 2.8, 1.2, 1.8, 2.6). Yield-related emissions for the three agricultural sites were 201, 248 and 269 kg CO2–C eq. (GJ net energy lactation; NEL)−1 for sites GW, GM and AR, respectively (SE 17, 9, 19). The carbon footprint of agricultural commodities grown on fen soils depended on long-term drainage intensity rather than type of management, but management and climate strongly influenced interannual on-site variability. However, arable forage production revealed a high uncertainty of yield and therefore was an unsuitable land use option. Lowest yield-related GHG emissions were achieved by a three-cut system of productive grassland swards in combination with a high GWL (long-term mean ≤  20 cm below the surface).

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Greenhouse gas emissions from fen soils used for forage production in northern Germany

10.5194/bg-2015-635 ◽

2016 ◽

Author(s):

Arne Poyda ◽

Thorsten Reinsch ◽

Christof Kluß ◽

Ralf Loges ◽

Friedhelm Taube

Keyword(s):

Ghg Emissions ◽

Forage Yield ◽

N2o Emissions ◽

Net Energy ◽

Forage Production ◽

Climatic Impact ◽

Northern Germany ◽

Northwest Germany ◽

Ch4 And N2o

Abstract. A large share of peatlands in northwest Germany is drained for agricultural purposes, thereby emitting high amounts of greenhouse gases (GHG). In order to quantify the climatic impact of fen soils in dairy farming systems of northern Germany, GHG exchange and forage yield were determined on four experimental sites which differed in terms of management and drainage intensity: a) rewetted and unutilized grassland (UG), b) intensive and 'wet' grassland (GW), c) intensive and 'moist' grassland (GM) and d) arable forage cropping (AR). Net ecosystem exchange (NEE) of CO2 and fluxes of CH4 and N2O were measured using closed manual chambers. CH4 fluxes were significantly affected by groundwater level (GWL) and soil temperature, whereas N2O fluxes showed a significant relation to the amount of nitrate in top soil. Annual balances of all three gases, as well as the global warming potential (GWP), were significantly correlated to mean annual GWL. Two-year mean GWP, combined from C2-C-equivalents of NEE, CH4 and N2O emissions, as well as C input (slurry) and C output (harvest), was 3.8, 11.7, 17.7 and 17.3 Mg CO2-C-eq ha−1 a−1 for sites UG, GW, GM and AR, respectively (standard error (SE) 2.8, 1.2, 1.8, 2.6). Yield related emissions for the three agricultural sites were 201, 248 and 269 kg CO2-C-eq (GJ net energy lactation (NEL))−1 for sites GW, GM and AR, respectively (SE 17, 9, 19). The carbon footprint of agricultural commodities grown on fen soils depended on long-term drainage intensity rather than type of management, but management and climate strongly influenced interannual on-site variability. However, arable forage production revealed a high uncertainty of yield and therefore was an unsuitable land use option. Lowest yield related GHG emissions were achieved by a three-cut system of productive grassland swards in combination with a high GWL (long-term mean ≤ 20 cm below the surface).

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An Analysis of Long-Term Scenarios for The GHG Emissions Projections Considering Economic Growth and Industrial Structure Change

Journal of Climate Change Research ◽

10.15531/ksccr.2016.7.3.257 ◽

2016 ◽

Vol 7 (3) ◽

pp. 257

Author(s):

Seung Moon Kwon ◽

Eui Chan Jeon

Keyword(s):

Economic Growth ◽

Industrial Structure ◽

Ghg Emissions ◽

Structure Change

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ESTUARINE RECORDS OF LONG-TERM HUMAN IMPACTS ON FLUVIAL SEDIMENT DISCHARGE FROM A LARGE NEW ENGLAND RIVER

10.1130/abs/2016se-273677 ◽

2016 ◽

Author(s):

Justin L. Shawler ◽

◽

Christopher J. Hein

Keyword(s):

New England ◽

Human Impacts ◽

Sediment Discharge ◽

Fluvial Sediment

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Distribution and altitudinal patterns of carbon and nitrogen storage in various forest ecosystems in the central Yunnan Plateau, China

Scientific Reports ◽

10.1038/s41598-021-85710-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jianqiang Li ◽

Qibo Chen ◽

Zhuang Li ◽

Bangxiao Peng ◽

Jianlong Zhang ◽

...

Keyword(s):

Forest Ecosystems ◽

Sustainable Forest Management ◽

Carbon And Nitrogen ◽

Pinus Yunnanensis ◽

Yunnan Plateau ◽

Baseline Information ◽

C And N ◽

Quercus Semecarpifolia ◽

Management Policies

AbstractThe carbon (C) pool in forest ecosystems plays a long-term and sustained role in mitigating the impacts of global warming, and the sequestration of C is closely linked to the nitrogen (N) cycle. Accurate estimates C and N storage (SC, SN) of forest can improve our understanding of C and N cycles and help develop sustainable forest management policies in the content of climate change. In this study, the SC and SN of various forest ecosystems dominated respectively by Castanopsis carlesii and Lithocarpus mairei (EB), Pinus yunnanensis (PY), Pinus armandii (PA), Keteleeria evelyniana (KE), and Quercus semecarpifolia (QS) in the central Yunnan Plateau of China, were estimated on the basis of a field inventory to determine the distribution and altitudinal patterns of SC and SN among various forest ecosystems. The results showed that (1) the forest SC ranged from 179.58 ± 20.57 t hm−1 in QS to 365.89 ± 35.03 t hm−1 in EB. Soil, living biomass and litter contributed an average of 64.73%, 31.72% and 2.86% to forest SC, respectively; (2) the forest SN ranged from 4.47 ± 0.94 t ha−1 in PY to 8.91 ± 1.83 t ha−1 in PA. Soil, plants and litter contributed an average of 86.88%, 10.27% and 2.85% to forest SN, respectively; (3) the forest SC and SN decreased apparently with increasing altitude. The result demonstrates that changes in forest types can strongly affect the forest SC and SN. This study provides baseline information for forestland managers regarding forest resource utilization and C management.

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