Li X.,Shandong Institute of Agriculture Sustainable Development |
Sun Z.,Fujian Normal University |
Sun W.,CAS Yantai Institute of Coastal Zone Research |
Zhu Z.,Shandong Institute of Agriculture Sustainable Development
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2015
The spatial and temporal variations of the fluxes of dimethylsulfide (DMS) and the key controlling factors in high tidal marsh (HTM), middle tidal marsh (MTM) and low tidal marsh (LTM) in the Yellow River estuary from April to December, 2012 were investigated by using static chamber-gas chromatography. The results showed that the DMS fluxes form HTM, MTM and LTM were 0.043~0.59 μg·m-2·h-1, 0.18~1.90 μg·m-2·h-1and 0.88~5.80 μg·m-2·h-1, and the average fluxes were 0.33 μg·m-2·h-1, 0.95 μg·m-2·h-1and 2.18 μg·m-2·h-1, respectively, indicating that the tidal marsh ecosystems in the Yellow River estuary acted as DMS source. Significant spatial and temporal variations of DMS emission were observed across the tidal marshes in the Yellow River estuary. The DMS emissions from the three tidal marshes were mainly focused on the growing season (from May to October) and differed significantly (p<0.05), in the order of LTM >MTM>HTM. The spatial variations of DMS emission were related to the spatial variations of seasons, vegetations, environmental factors and soil substrate. The dominant factor affected the DMS emission in HTM was 0 cm temperature and that in LHM was 0~5 cm soil volumetric water, while no dominant factor was found in MHM, implying that the DMS fluxes from MHM might be influenced by many factors. The results of this paper can provide essential data for further studying the sulfur cycle in the natural wetland of the Yellow River estuary and its influence on atmospheric environment. © 2015, Science Press. All right reserved.
Yang F.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research |
Yang J.,Shandong Institute of Agriculture Sustainable Development |
Wang J.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research |
Zhu Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2015
Leaf area index (LAI) is a critical variable for simulating the carbon or nitrogen cycles and water and heat energy balance of ecosystem. MODIS and Geoland2 version 1 (GEOV1) LAI products were validated based on the ground-measured maize, winter wheat, and grass LAI data in several years. This study also investigated the residential area effect in mixed pixels on global LAI product accuracies in North Plain and Northeastern Plain in China. The MODIS and GEOV1 LAI products showed marked difference in variations of maize and winter wheat LAI at different key growth stages, and the GEOV1 LAI can present much clear differences and variations during crop growth periods. The MODIS and GEOV1 LAI products often underestimate the maize and winter wheat LAI, with the exception that GEOV1 LAI overestimate when maize LAI is large. For grass, the MODIS and GEOV1 LAI both overestimate a little. Overall, the GEOV1 LAI is often larger than the MODIS LAI. The GEOV1 LAI showed better regressions (with R2 of 0.868, 0.496, and 0.216) with the ground-measured LAI than MODIS LAI (with R2 of 0.258, 0.350, and 0.129) for maize, winter wheat, and grass, respectively. The residential area in mixed pixel make marked impact on MODIS and GEOV1 LAI data at different maize and winter wheat growth stages, and it maybe a main error source of the MODIS and GEOV1 LAI underestimations. The quadratic polynomial fitting relationships (most of the regressions R2 exceeded 0.90) can describe well the effect of residential area percent in mixed pixel on global LAI product. © 2014 IEEE.
Li X.-H.,Shandong Institute of Agriculture Sustainable Development |
Guo H.-H.,Shandong Academy of Agricultural Sciences |
Yang L.-P.,Shandong Institute of Agriculture Sustainable Development |
Zhu Z.-L.,Shandong Institute of Agriculture Sustainable Development |
Sun X.-Q.,Shandong Institute of Agriculture Sustainable Development
Huanjing Kexue/Environmental Science | Year: 2014
The H2S and COS emission fluxes from Suaeda salsa marsh in the Yellow River estuary were measured using the static chamber and Chromatogram method during the growth season (May to October), the results showed that the seasonal and diurnal variations of H2S and COS emission fluxes were obvious, and Suaeda salsa marsh in the Yellow River estuary was the sources for both H2S and COS during the growth time, and the mean H2S and COS emission fluxes from Suaeda salsa marsh were 4.97 μg ·(m2·h)-1 and 0.92 μg ·(m2·h)-1, respectively. Different environmental factors had different effects on the emission fluxes of H2S and COS from Suaeda salsa marsh, in which the SO4 2- content and water content in the soil were the main factors that affected the H2S and COS emission fluxes, respectively. Sulfur gases emissions from Suaeda salsa marsh may be affected by many factors, such as plant, tide status and so on, so that should be further studied.
Zhigao S.,CAS Yantai Institute of Coastal Zone Research |
Xiaojie M.,CAS Yantai Institute of Coastal Zone Research |
Xiaojie M.,CAS Changchun Northeast Institute of Geography and Agroecology |
Xiaojie M.,University of Chinese Academy of Sciences |
And 7 more authors.
Chinese Geographical Science | Year: 2011
Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution characteristics of stable isotope, then reviewed the recent advances and applications of stable isotope in the C and N biogeochemical cycles of ecosystem. By applying the 13C natural abundance technique, ecologists are able to understand the photosynthetic path and CO2 fixation of plants, the CO 2 exchange and C balance status of ecosystem, the composition, distribution and turnover of soil organic C and the sources of organic matter in food webs, while by using the 13C labeled technique, the effects of elevated CO2 on the C processes of ecosystem and the sources and fate of organic matter in ecosystem can be revealed in detail. Differently, by applying the 15N natural abundance technique, ecologists are able to analyze the biological N2-fixation, the N sources of ecosystem, the N transformation processes of ecosystem and the N trophic status in food webs, while by using the 15N labeled technique, the sources, transformation and fate of N in ecosystem and the effects of N input on the ecosystem can be investigated in depth. The applications of both C and N isotope natural abundance and labeled techniques, combined with the elemental, other isotope (34S) and molecular biomarker information, will be more propitious to the investigation of C and N cycle mechanisms. Finally, this paper concluded the problems existed in current researches, and put forward the perspective of stable isotope techniques in the studies on C and N biogeochemical cycles of ecosystem in the future. © Science Press, Science Press, Northeast Institute of Geography and Agroecology, CAS and Springer-Verlag Berlin Heidelberg 2011.