Global Environmental Forum

Tsukuba, Japan

Global Environmental Forum

Tsukuba, Japan
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Natsumeda T.,Global Environmental Forum | Natsumeda T.,Ibaraki University | Takamura N.,Japan National Institute of Environmental Studies | Nakagawa M.,Japan National Institute of Environmental Studies | And 3 more authors.
Limnology | Year: 2015

We compared the environmental and biotic characteristics of farm ponds with and without the invasive fish, largemouth bass (Micropterus salmoides), and bluegill (Lepomis macrochirus), with varying degrees of aquatic vegetation cover in western Japan. Redundancy analysis (RDA) revealed that aquatic vegetation cover and pond area were significant environmental variables in explaining the variance in aquatic organisms. Aquatic vegetation cover predominantly affected Odonata and Hemiptera larvae, and the native cyprinid, Hemigrammocypris rasborella, while the pond area mainly affected the two exotic fishes (largemouth bass and bluegill), Viviparidae, Oligocheata, Ephemeroptera, and chironomid larvae. In the RDA biplot for aquatic organisms, the RDA1 axis appeared to separate the exotic fish group (bluegill, largemouth bass, Gammaridae, Oligochaeta, Viviparidae, Ephemeroptera, Trichoptera, and chironomid larvae) from the native fish group (H. rasborella, Oryzias latipes, Rhinogobius sp., Odonata, shrimps, and Hemiptera larvae). The best path model results indicated that the presence of piscivorous largemouth bass had a significantly negative effect on native fish numbers; largemouth bass also had a positive indirect effect on benthic organism numbers. Our data suggest that the depletion of native fishes via top-down effects by exotic largemouth bass may indirectly increase the number of benthic organisms as a result of trophic-cascading effects. © 2015, The Japanese Society of Limnology.

Sasakawa M.,Japan National Institute of Environmental Studies | Ito A.,Japan National Institute of Environmental Studies | Machida T.,Japan National Institute of Environmental Studies | Tsuda N.,Global Environmental Forum | And 4 more authors.
Tellus, Series B: Chemical and Physical Meteorology | Year: 2012

We described continuous measurements of CH 4 and CO 2 concentration obtained at two sites placed in the middle taiga, Karasevoe (KRS) and Demyanskoe (DEM), in West Siberian Lowland (WSL) from 2005 to 2009. Although both CH 4 and CO 2 accumulation (ΔCH 4 and ΔCO 2) during night-time at KRS in June and July 2007 showed an anomalously high concentration, higher ratios of DCH4/DCO2 compared with those in other years indicated that a considerably higher CH4 flux occurred relative to the CO 2 flux. The daily CH 4 flux calculated with the ratio of ΔCH 4/ΔCO 2 and terrestrial biosphere CO 2 flux from an ecosystem model showed a maximum in July at the both sites. Although anomalously high flux was observed in June and July 2007 at KRS, only a small flux variation was observed at DEM. The high regional CH 4 flux in June and July 2007 at KRS was reproduced using a process-based ecosystem model, Vegetation Integrative Simulator for Trace gases (VISIT), in response to high water table depth caused by the anomalously high precipitation during the summerof 2007. © 2012 M. Sasakawa et al.

Sasakawa M.,Japan National Institute of Environmental Studies | Machida T.,Japan National Institute of Environmental Studies | Tsuda N.,Global Environmental Forum | Arshinov M.,Zuev Institute of Atmospheric Optics | And 3 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2013

In situ measurements of the vertical distribution of carbon dioxide (CO2) carried out with a light aircraft over a tower site (Berezorechka; 56°08'45''N, 84°19'49''E) in the taiga region of West Siberia from October 2001 to March 2012 document the detailed seasonal and vertical variation of CO2 concentrations during daytime. The variation appears to be controlled mainly by the CO2 flux from taiga ecosystems and the height of the planetary boundary layer (PBL). We calculated average CO2 concentrations in the PBL and the lower free troposphere (LFT), both of which show clear seasonal cycles and an increasing long-term trend. Seasonal amplitude in the PBL had a larger value (29 ppm) than that in the LFT (14 ppm), demonstrating strong CO2 source-sink forcing by the taiga ecosystems. Mean CO2 concentrations during 13:00-17:00 local standard time observed at the four levels of the tower (5, 20, 40, and 80 m) showed lower CO2 concentrations than that observed in the PBL by aircraft during June-August (growing season). This negative bias decreased with increasing inlet height such that the minimum difference appeared at the 80-m inlet (-2.4 ± 0.8 ppm). No such bias was observed during other months (dormant season). The daytime CO2 flux, based on multiple vertical profiles obtained on a single day, ranged from -36.4 to 3.8 μmolm -2 s-1 during July-September. There was a clear difference in the fluxes between the morning and afternoon, suggesting that these data should be considered examples of fluxes during several daytime hours from the West Siberian taiga. © 2013. Her Majesty the Queen in Right of Canada. American Geophysical Union.

Miyamoto Y.,Osaka University | Majima T.,Osaka University | Arai S.,Hill Research | Katsumata K.,Global Environmental Forum | And 7 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2011

The irradiation of a free electron laser at Tokyo University of Science (FEL-TUS) to β-propiolactone molecules in the gas phase has efficiently induced the infrared multiple photon dissociation of the compound in the wavenumber regions of 1000-1100 and 1700-2000 cm-1. The products were carbon dioxide and ethylene at equal amounts, where carbon dioxide was enriched with 13C under selected irradiation conditions. The relative yields of products and the selectivity of 13C were examined under various experimental conditions; the maximum 13C atom fraction of 59% was achieved when 2.5 Torr β-propiolactone was irradiated by FEL pulses at 1750 cm-1 with a fluence of 5.8 J cm-2. One of the reasons of this high selectivity is a large isotope shift of ∼47 cm-1 for the CO stretching vibration around 1880 cm-1, which is larger than the energy resolution of FEL-TUS. Another possible factor may be a shorter micropulse interval (∼350 ps) of FEL-TUS than the collisional frequency of β-propiolactone molecules in the gas phase, which prevents the collisional energy transfer from 13C molecules to 12C molecules during successive micropulses. © 2010 Elsevier B.V. All rights reserved.

Watai T.,Global Environmental Forum | Machida T.,Japan National Institute of Environmental Studies | Shimoyama K.,Japan National Institute of Environmental Studies | Shimoyama K.,Hokkaido University | And 3 more authors.
Journal of Atmospheric and Oceanic Technology | Year: 2010

Observations of the atmospheric CO2 concentration from a 90-m tower in Berezorechka, western Siberia, that have taken place since October 2001 were used to characterize CO2 variations over a vast boreal forest area. A new CO2 standard gas saving system was developed that reduced the consumption of standard gases and kept the analysis precision to within 0.3 μmol mol-1. The CO2 day-to-day variation correlated well with atmospheric stability. The average amplitudes of the diurnal variation at 80 m were found to be about 17 and 1.5 μmol mol-1 in July and December 2003, respectively. Extremely high daytime CO2 concentrations of greater than 400 μmol mol-1 were occasionally observed during the winter, which were caused by anticyclonic atmospheric conditions lasting more than several days. Afternoon CO2 values observed at the 80-m height agreed to within 0.4 μmol mol21 with aircraft CO2 measurements taken in the planetary boundary layer; disagreements were found for anticyclonic conditions in the winter. The afternoon CO2 values reached their maximum in mid-January and their minimum late in July, with the seasonal amplitude of 30.9 μmol mol-1. Compared to observations at background stations, this observation tower recorded a larger seasonal amplitude and earlier occurrence of the seasonal minimum. © 2010 American Meteorological Society.

Sasakawa M.,Japan National Institute of Environmental Studies | Shimoyama K.,Hokkaido University | Machida T.,Japan National Institute of Environmental Studies | Tsuda N.,Global Environmental Forum | And 8 more authors.
Tellus, Series B: Chemical and Physical Meteorology | Year: 2010

We have been conducting continuous measurements of Methane (CH4) concentration from an expanding network of towers (JR-STATION: Japan-Russia Siberian Tall Tower Inland Observation Network) located in taiga, steppe and wetland biomes of Siberia since 2004. High daytime means (>2000 ppb) observed simultaneously at several towers during winter, together with in situ weather data and NCEP/NCAR reanalysis data, indicate that high pressure systems caused CH4 accumulation at subcontinental scale due to the widespread formation of an inversion layer. Daytime means sometimes exceeded 2000 ppb, particularly in the summer of 2007 when temperature and precipitation rates were anomalously high over West Siberia, which implies that CH4 emission from wetlands were exceptionally high in 2007. Many hot spots detected by MODIS in the summer of 2007 illustrate that the contribution of biomass burning also cannot be neglected. Daytime mean CH4 concentrations from the Siberian tower sites were generally higher than CH4 values reported at NOAA coastal sites in the same latitudinal zone, and the difference in concentrations between two sets of sites was reproduced with a coupled Eulerian-Lagrangian transport model. Simulations of emissions from different CH4 sources suggested that the major contributor to variation switched from wetlands during summer to fossil fuel during winter. © 2010 The Authors Tellus B © 2010 International Meteorological Institute in Stockholm.

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