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Zhang L.-H.,Fujian Normal University | Tong C.,Fujian Normal University | Tong C.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | Zeng C.-S.,Fujian Normal University | Zeng C.-S.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education
Huanjing Kexue/Environmental Science | Year: 2014

Characteristics of diurnal and seasonal variations of surface atmospheric CO2 concentration were analyzed in the Minjiang River estuarine marsh from December 2011 to November 2012. The results revealed that both the diurnal and seasonal variation of surface atmospheric CO2 concentration showed single-peak patterns, with the valley in the daytime and the peak value at night for the diurnal variations, and the maxima in winter and minima in summer for the seasonal variation. Diurnal amplitude of CO2 concentration varied from 16.96 μmol·mol-1 to 38.30 μmol·mol-1. The seasonal averages of CO2 concentration in spring, summer, autumn and winter were (353.74 ± 18.35), (327.28 ± 8.58), (354.78 ± 14.76) and (392.82 ± 9.71) μmol·mol-1, respectively, and the annual mean CO2 concentration was (357.16 ± 26.89) μmol·mol-1. The diurnal CO2 concentration of surface atmospheric was strongly negatively correlated with temperature, wind speed, photosynthetically active radiation and total solar radiation (P < 0.05). The diurnal concentration of CO2 was negatively related with tidal level in January, but significantly positively related in July. Source


Yang P.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | Yang P.,Fujian Normal University | Tong C.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | Tong C.,Fujian Normal University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Greenhouse gas (GHGs) emissions from freshwater ecosystems are a major component of global terrestrial landscape budgets. Currently, global warming is affecting these ecosystems and may trigger an increase in GHGs emissions, which may further enhance global warming. The identification and accurate quantification of aquatic ecosystems as sinks/sources of GHGs are vital for evaluating GHGs budgets and assessing possible climate feedback effects in order to improve climate models. In recent years, fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) have been observed from freshwater aquatic environments such as natural lakes, hydropower reservoirs, rivers, ponds, and drainage ditches. This review analyzes and summarizes research developments in GHGs emission paths, observation methods, and key factors affecting emissions from freshwater ecosystems. The mechanism of greenhouse gas production is a complex and interactive process that includes biochemical processes. The main emission paths from aquatic environments are diffusive fluxes across the air-water interface, bubble (ebullition) fluxes resulting from supersaturation of sediment, and plant-mediated fluxes. Attention has been recently been drawn to other emission pathways that contribute to total gas emissions at reservoir surfaces (e.g., gas release immediately below turbines and emissions further downstream in rivers). The monitoring methods vary for aquatic ecosystem emission pathways. Bubble fluxes are measured by funnel techniques, open dynamic floating methods, and ultrasonic detection technologies. Diffusive fluxes are measured by static chamber techniques, model estimations, micrometeorology, and tunable diode laser absorption spectroscopy (TDLAS). GHGs emission is conventionally measured using closed chamber to trap plant-mediated flux components. In addition, we discuss the impacts of physical, biological, hydrodynamic, and anthropogenic factors on GHGs emissions from aquatic ecosystems. We point out that an urgent and key direction for the future is to standardize the observation methods for GHGs fluxes from freshwater aquatic ecosystems and to consider temporal and spatial variability, which rely on long-term field observation. © 2015 Ecological Society of China. All rights reserved. Source


Yang P.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | Yang P.,Fujian Normal University | He Q.-H.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | He Q.-H.,Fujian Normal University | And 2 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2015

Quantifying response of soil methane production potential to temperature change in different wetland vegetation are vital to accurately evaluate effect of climate change on wetland ecosystem carbon balance. Soil samples at a depth of 0~30 cm (5 cm interval) from three typical tidal marsh ecosystems dominated by Cyperus malaccensis, Phragmites australis and Spartina alterniflora, respectively, in the Min River estuary were collected in February 2012, and soil methane production potentials were determined using anaerobic incubation method. The results showed that there is an exponential correlation between methane production potential and soil temperature. The averaged Q10 value of three marsh vegetation zones were 5.04, 14.92, 14.81, and 3.56, 4.99, 3.43, respectively, with temperature rasing from 10 to 20℃ and from 20 to 30℃. Vegetation type, incubation temperature and soil depth had significant effects on the methane production potential and Q10 value (P<0.05). ©, 2015, Chinese Society for Environmental Sciences. All right reserved. Source


Zhang Z.C.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | Zhang Z.C.,Fujian Normal University | Yang P.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | Yang P.,Fujian Normal University | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Sea level rise increases the frequency and intensity of saltwater intrusion events, and it affects the soil biogeochemical cycle in estuarine freshwater and brackish wetlands. A laboratory study measured the methane production potentials during from the topsoil of two freshwater Cyperus malaccensis marshes and two brackish C. malaccensis marshes during 12 days of incubation when exposed to varying salinities (0, 5, 10, 15, and 21 g/L of seawater or salt [NaCl] solutions). Seawater addition with a salinity range from 5 to 21 g/L induced a progressive suppression of methane production potentials. For all levels of salinity, except the freshwater control, more than 93% of methane production potential was inhibited, whereas there was no significant difference of suppression effects on methane production potentials upon the addition of seawater with a salinity range from 10 to 21 g/L. Ionic stress (represented by NaCl) reduced methane production potentials in both 15 and 21 g/L NaCl addition treatments; 5 and 10 g/L NaCl treatments did not significantly reduce methane production potentials (percentage of inhibition was less than 30%). Our results indicate that SO4 2- reduction, not osmotic stress by chloride ions, is the main process suppressing methane production in estuarine freshwater and brackish marshes following seawater intrusion. © 2015, Ecological Society of China. All rights reserved. Source


Wang W.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | Wang W.,Fujian Normal University | Xu L.,Fujian Normal University | Zeng C.,Key Laboratory of Humid Sub tropical Eco geographical Process of Ministry of Education | And 5 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

The ecological stoichiometric ratios of carbon (C), nitrogen (N) and phosphorus (P) are the properties of ecosystem process and function. The seasonal dynamics of C, N and P in live plant-litter-soil system were measured in Phragmites australis and Cyperus malaccensis var. brevifolius wetlands from Minjiang River estuary. The results showed that seasonal averaged C, N and P concentrations were C>N>P in live plant, litter and soil. C and N concentrations were higher in live plant, litter than soil and the order of P concentration was uncertain between various plant organs and soil. Seasonal averaged C, N, P stoichiometric ratios were C:P>C:N>N:P in live plant, litter and soil in the two wetlands. C:N in P. australis wetland was in order of litter>live plant>soil, while they were in order of live plant>litter>soil in C. malaccensis var. brevifolius wetland. C:P and N:P were litter>live plant>soil in both wetlands. The C, N, P stoichiometric ratios may reflect the exchange of C, N, P and the ecological function of plant community. Source

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