Spatial and temporal variation of nitrous oxide and methane flux between subtropical mangrove sediments and the atmosphere

Song

et al. 2013

Ecological Engineering

a b s t r a c tSalt-affected soils are extensively present and constitute about 7% of total land surface. However, our knowledge about nitrous oxide (N 2 O) production through rapid nitrification and denitrification processes between the atmosphere and the saline soil is very limited. In order to evaluate the potential of N 2 O consumption in saline soils, this study was therefore designed to quantify the variability in N 2 O emissions monthly in the Yellow River Delta in China. Main issues include: different saline-alkaline soils and temporal aspects. Our aim was to quantify N 2 O emissions and identify the major drivers controlling its emissions for providing guidance in eco-restoring coastal wetland on large scale. By using in situ closed chambers the annual average emissions of N 2 O from the mudflat was determined and it was significantly higher than plant communities, especially herbage communities. In general, the emissions of N 2 O of different ecosystems showed a unique-peak annual pattern, with the peak in September. Saline-alkaline mudflat and different vegetations acted as N 2 O source in the Yellow River Delta and the N 2 O emission of different ecosystems followed the order: Saline-alkaline mudflat > T. chinensis >S. salsa > P. australis. Therefore restoration of saline land through revegetation was necessary to reduce the N 2 O emission of saline soils. The effects of air and soil temperature on N 2 O fluxes were significant in salt-affected soils except P. australis. Soil water content and electrical conductivity correlated positively or negatively with N 2 O emissions in mudflat and P. australis community. While relationships between N 2 O production and other soil properties (TC, TN, C:N ratio, NH 4 + -N and NO 3 − -N) were only significant in mudflat and T. chinensis community. Temporal variations of N 2 O emission were related to the interactions of abiotic factors (air and soil temperature, soil water content and electrical conductivity) and the variations of other soil properties, while spatial variations were mainly affected by the vegetation composition at spatial scale.

Section: Discussionmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 98%

Seasonal dynamics in nitrous oxide emissions under different types of vegetation in saline-alkaline soils of the Yellow River Delta, China and implications for eco-restoring coastal wetland

Song

et al. 2013

Ecological Engineering

“…The productivity factor was a ratio of net primary productivity for each wetland ecosystem to net primary productivity of tropical rainforest (Equation 12) assuming that methane production in a tropical rainforest is constant throughout the year because of relatively constant temperatures and rainfall [29], i.e., (12) where: R = Productivity factor NPP = Net primary productivity.…”

Section: Productivity Factormentioning

confidence: 99%

“…Furthermore, they found that accurate and easily reproducible land-cover maps using remote sensing products, which specifically enhance their extent and characteristics, would improve monitoring and land management decisions. Methane fluxes emitted from wetlands were also found to differ significantly between sampling seasons and may increase with climate change by the end of the century [12,13].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling Methane Emission from Wetlands in North-Eastern New South Wales, Australia Using Landsat ETM+

et al. 2010

Natural wetlands constitute a major source of methane emission to the atmosphere, accounting for approximately 32 ± 9.4% of the total methane emission. Estimation of methane emission from wetlands at both local and national scale using process-based models would improve our understanding of their contribution to global methane emission. The aim of the study is to estimate the amount of methane emission from the coastal wetlands in north-eastern New South Wales (NSW), Australia, using Landsat ETM+ and to estimate emission with a temperature increase. Supervised wetland classification was performed using the Maximum Likelihood Standard algorithm. The temperature dependent factor was obtained through land surface temperature (LST) estimation algorithms. Measurements of methane fluxes from the wetlands were performed using static chamber techniques and gas chromatography. A process-based methane emission model, which included productivity factor, wetland area, methane flux, precipitation and evaporation ratio, was used to estimate the amount of methane emission from the wetlands. Geographic information system (GIS) provided the framework for analysis. The variability of methane emission from the wetlands was high, with forested wetlands found to produce the highest amount of methane, i.e., 0.0016 ± 0.00009 teragrams (Tg) in the month of June, 2001. This would increase to 0.0022 ± 0.0001 Tg in the month of June with a 1 °C rise in mean annual temperature by the year 2030 in north-eastern NSW, Australia. OPEN ACCESSRemote Sensing 2010, 2 1379

Limnology & Oceanography

Benthic microalgae offset the sediment carbon dioxide emission in subtropical mangrove in cold seasons

Chen

Chmura

Wang

et al. 2019

Our study examined the relationship of microphytobenthos to greenhouse gas fluxes from sediments of a subtropical mangrove forest and adjacent mudflat in the Jiulong River Estuary, South China. The relationship between chlorophyll a concentration at the sediment surface and diatom density confirmed that these microalgae were the important component of the microphytobenthos, which produced an observable biofilm in cold seasons (winter and spring) on both the mangrove and mudflat sediment surfaces. Fluxes of methane and nitrous oxide were not affected by the microalgae film and were similar between the mangrove and mudflat. However, benthic microalgae affected the sediment to atmosphere carbon dioxide (CO 2 ) flux, and the effect was temporally variable with the seasonal change in microalgae abundance. In the cold seasons, the mangrove sediment was a CO 2 sink under light chambers but a source under dark chambers. In summer, when there was no visible microalgae film at the sediment surface, the intertidal sediments had CO 2 emissions and comparable fluxes between the two chambers. The negative daily CO 2 fluxes of the film-covered sediment (as the average of the dark and light fluxes) and positive flux of the sediment without visible biofilm indicated that the occurrence of microalgae film converted the mangrove sediment from a CO 2 source to a sink and that the photosynthesis of the microalgae film offset the sediment respiration during the cold seasons in this study. We also found similar effects of microalgae on CO 2 fluxes on the nonvegetated mudflat.