Nagoya University · Environmental Science
Professor Urumu Tsunogai's research lab specializes in environmental isotope geochemistry, focusing on the isotopic composition of water, nitrate, and atmospheric gases to trace biogeochemical cycles in terrestrial, aquatic, and atmospheric systems. The lab investigates the origins, transformations, and transport mechanisms of nitrogen and sulfur species in ecosystems, with particular emphasis on stable isotopes (e.g., δ¹⁵N, Δ¹⁷O) and radiocarbon to understand atmospheric deposition, groundwater chemistry, and environmental change. Their work spans from remote marine atmospheres to mountainous lakes and urban-remote gradients, offering insights into natural processes and anthropogenic impacts.
Figures are computed from collected data and may differ slightly.
Chloride (Cl – ) and sulfate (SO 4 2– ) ion concentrations of ground water issuing from two wells located near the epicenter of the Kobe earthquake in Japan fluctuated before the disastrous magnitude 7.2 event on 17 January 1995. The samples measured were pumped ground water packed in bottles and distributed in the domestic market as drinking water from 1993 to April 1995. Analytical results demonstrate that Cl – and SO 4 2– concentrations increased steadily from August 1994 to just before the e
C 2 ‐C 5 non‐methane hydrocarbons (NMHCs) and methyl chloride in the remote maritime atmosphere over the western North Pacific are analyzed in regard to their variation of mixing ratio and 13 C/ 12 C ratio (δ 13 C), together with those in polluted urban (Nagoya and Yokohama) and coastal (Tokyo Bay) atmospheres in Japan. NMHCs show large atmospheric mixing ratio differences between urban (coastal) and maritime atmospheres probably due to emission from urban areas and degradation within the mariti
Abstract. The stable isotopic compositions of nitrate in precipitation (wet deposition) and groundwater (spring, lake, and stream water) were determined for the island of Rishiri, Japan, so as to use the 17O anomalies (Δ17O) to trace the fate of atmospheric nitrate that had deposited onto the island ecosystem, which is a representative background forest ecosystem for eastern Asia. The deposited nitrate had large 17O anomalies with Δ17O values ranging from +20.8‰ to +34.5‰ (n = 32) with +26.2‰ be
Abstract. The stable isotopic compositions of nitrate, including the 17O anomalies (Δ17O), were determined twice in 1 yr (June and August 2007) in the oligotrophic water column of Lake Mashu, Japan. These data were then used to quantify the geochemical dynamics of nitrate in the lake, by using the deposition rate of the atmospheric nitrate onto the entire catchment area of the lake. The total amount of nitrate in the lake water decreased from 4.2 to 2.1 Mmol during the period between the observa
We present a method for high-sensitivity nitrogen isotopic analysis of particulate organic nitrogen (PON) in seawater and freshwater, for the purpose of determining the aquatic nitrogen fixation rate through the 15N2 tracer technique for samples that contain a low abundance of organisms. The method is composed of the traditional oxidation/reduction methods, such as the oxidation of PON to nitrate (NO3*) using persulfate, the reduction of NO3* to nitrite (NO2*) using spongy cadmium, and further r
Open papers in the app to read, cite, and organize with AI.
