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Aramaki T.,National Institute for Environmental Studies | Nagao S.,Kanazawa University | Nakamura Y.-H.,Hokkaido University | Uchida M.,Japan National Institute of Environmental Studies | Shibata Y.,Japan National Institute of Environmental Studies
Radiocarbon | Year: 2010

During a rainfall event in early September 2006, the transport behavior of particulate organic carbon (POC) in a small river (Teshio River, northern Japan) with alluvial plain and forest characteristics was investigated chiefly with carbon isotopes. The radiocarbon (δ14C value) of POC varied widely from 56‰ at the beginning of the rain event to 10‰ at peak rainfall. The δ14C values have a positive correlation with C/N ratios and a negative correlation with δ13C values except for the data from when both turbidity and water level were at their maximums due to rainfall. These results indicate that the sources of organic matter in the river come from the surface layer of soil as the water level rises during a rainfall event. © 2010 by the Arizona Board of Regents on behalf of the University of Arizona. Source

Lee D.K.,Seoul National University | Park C.,National Institute for Environmental Studies | Tomlin D.,University of Pennsylvania
Landscape and Ecological Engineering | Year: 2013

The amount of carbon stored in soil and vegetation varies according to land use. Land-use changes (LUCs) affect those carbon stocks. Changes in carbon stocks also affect greenhouse gas emissions. Predicting LUCs is therefore necessary to establish quantitative targets for carbon dioxide (CO2) reduction. This study attempts to model LUCs and the associated changes in carbon stocks for South Korea between 2005 and 2030. It examines four LUC scenarios suggested by the Intergovernmental Panel on Climate Change. Each scenario is assessed in terms of its effect on South Korean carbon stocks. Under all four scenarios, afforestation leads to carbon sequestration with an average net uptake of 22.4-31.5 MtC. The scenario yielding the highest sequestration rate increase (from 12.4 to 14.1 MtC/year) results in levels of sequestration equal to 8.3 % of South Korea's 2005 CO2 emissions. This is equivalent to a value of 304 million dollars in the European Union carbon market. Clear differences among the scenarios tested suggest that land use must be regarded as an important factor in any plan for future carbon sequestration. © 2013 International Consortium of Landscape and Ecological Engineering and Springer Japan. Source

Shiogama H.,Japan National Institute of Environmental Studies | Emori S.,National Institute for Environmental Studies | Emori S.,University of Tokyo | Takahashi K.,Japan National Institute of Environmental Studies | And 5 more authors.
Journal of Climate | Year: 2010

The precipitation sensitivity per 1 K of global warming in twenty-first-century climate projections is smaller in an emission scenario with larger greenhouse gas concentrations and aerosol emissions, according to the Model for Interdisciplinary Research on Climate 3.2 (MIROC3.2) coupled atmosphere-ocean general circulation model. The authors examined the reasons for the precipitation sensitivity to emission scenarios by performing separated individual forcing runs under high and low emission scenarios. It was found that the dependency on emission scenario is mainly caused by differences in black and organic carbon aerosol forcing (the sum of which is cooling forcing) between the emission scenarios and that the precipitation is more sensitive to carbon aerosols than well-mixed greenhouse gases. They also investigated the reason for the larger precipitation sensitivity (larger magnitude of precipitation decrease per 1 K cooling of temperature) in the carbon aerosol runs. Surface dimming due to the direct and indirect effects of carbon aerosols effectively decreases evaporation and precipitation, which enhances the precipitation sensitivity in the carbon aerosol runs. In terms of the atmospheric moisture cycle, although changes of vertical circulation offset the effects of changes in the atmospheric moisture in both the carbon aerosol and greenhouse gas runs, the amplitude of vertical circulation change per 1 K temperature change is less in the carbon aerosol runs. Furthermore, the second indirect effect of organic carbon aerosol counteracts the influence of the vertical circulation change. These factors lead to suppression of changes in the moisture's atmospheric residence time and increase of the precipitation sensitivity in the carbon aerosol runs. © 2010 American Meteorological Society. Source

Sakurai T.,National Institute for Environmental Studies | Kobayashi J.,National Institute for Environmental Studies | Kobayashi J.,Prefectural University of Kumamoto | Kinoshita K.,National Institute for Environmental Studies | And 13 more authors.
Environmental Toxicology and Chemistry | Year: 2013

The authors investigated the kinetics of transfer of perfluorooctane sulfonate (PFOS) from water, suspended sediment, and bottom sediment to a marine benthic fish, the marbled flounder (Pseudopleuronectes yokohamae). Fish were exposed in 3 treatments to PFOS in combinations of these exposure media for 28 d and then depurated for 84 d. A major part (37-66%) of PFOS in the fish was in the carcass (i.e., whole body minus muscle and internal organs). Three first-order-kinetic models that differed in exposure media, that is, 1) sum of dissolved and particulate phases and sediment; 2) dissolved phase, particulate phase, and sediment; and 3) dissolved phase only, were fitted to the data assuming common rate constants among the treatments. The uptake efficiency of dissolved PFOS at the respiratory surfaces was estimated to be 3.2% that of oxygen, and the half-life of PFOS in the whole body to be 29 d to 31 d. The better fit of models 1 and 2 and the values of the estimated uptake rate constants suggested that the PFOS in suspended and bottom sediments, in addition to that dissolved in water, contributed to the observed body burden of the fish. Based on an evaluation of several possible contributing factors to the uptake of PFOS from suspended and bottom sediments, the authors propose that further investigation is necessary regarding the mechanisms responsible for the uptake. Environ Toxicol Chem 2013;32:2009-2017. © 2013 SETAC. Source

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