A5085828577- Soil Carbon and Nitrogen Dynamics
- Isotope Analysis in Ecology
- Soil and Water Nutrient Dynamics
- Groundwater and Isotope Geochemistry
- Peatlands and Wetlands Ecology
- Wastewater Treatment and Nitrogen Removal
- Microbial Community Ecology and Physiology
- Marine and coastal ecosystems
- Geology and Paleoclimatology Research
- Hydrology and Watershed Management Studies
- Methane Hydrates and Related Phenomena
- Plant nutrient uptake and metabolism
- Lichen and fungal ecology
- Plant Ecology and Soil Science
- Fish Ecology and Management Studies
- Atmospheric and Environmental Gas Dynamics
- Atmospheric chemistry and aerosols
- Botany and Plant Ecology Studies
- Plant Water Relations and Carbon Dynamics
- Mycorrhizal Fungi and Plant Interactions
- Microbial Fuel Cells and Bioremediation
- Seedling growth and survival studies
- Radioactive contamination and transfer
- Climate change and permafrost
- Phytochemistry and Biological Activities
Kyoto University
2012-2024
Centre for Ecological Research
2016-2024
Tokyo University of Agriculture and Technology
2011-2021
University of Lomé
1970-2021
University of Kara
2021
Tohoku University
2021
Tokyo Metropolitan University
2021
Suzuki (Japan)
2021
The Japanese Society of Gastroenterological Surgery
2021
Hudson Institute
2021
Hadal oceans at water depths below 6,000 m are the least-explored aquatic biosphere. The Challenger Deep, located in western equatorial Pacific, with a depth of ∼11 km, is deepest ocean on Earth. Microbial communities associated waters from sea surface to trench bottom (0∼10,257 m) Deep were analyzed, and unprecedented microbial identified hadal (6,000∼10,257 that distinct abyssal communities. potentially chemolithotrophic populations less abundant than those upper waters. emerging members...
Significance Nitrogen (N) losses from terrestrial ecosystems can occur as inert forms or heat-trapping greenhouse gases, and via nitrate (NO 3 − ) leaching to drainage waters, which contribute eutrophication anoxia in downstream ecosystems. Here, we use natural isotopes demonstrate that microbial gaseous N production denitrification is the dominant pathway of NO removal forest ecosystems, with are up ∼60-fold higher than those based on traditional techniques. Denitrification becomes less...
Abstract The impacts of enhanced nitrogen (N) deposition on the global forest carbon (C) sink and other ecosystem services may depend whether N is deposited in reduced (mainly as ammonium) or oxidized forms nitrate) subsequent fate each. However, fates two key reactive their contributions to C sinks are unclear. Here, we analyze results from 13 ecosystem-scale paired 15 N-labelling experiments temperate, subtropical, tropical forests. Results show that total retention similar for ammonium...
Abstract There is increasing concern over the impact of atmospheric nitrogen (N) deposition on forest ecosystems in tropical and subtropical areas. In this study, we quantified N revealed current plant soil status 14 forests along a 150 km urban to rural transect southern China, with an emphasis examining whether foliar δ 15 can be used as indicator saturation. Bulk ranged from 16.2 38.2 kg ha −1 yr , while throughfall covered larger range 11.7–65.1 . Foliar concentration, NO 3 − leaching...
The natural abundance of 13 C and 15 N was measured in basidiocarps at least 115 species 88 genera ectomycorrhizal, wood‐decomposing litter‐decomposing fungi from Japan Malaysia. also leaves, litter, soil wood three different sites. were enriched ectomycorrhizal fungi, respectively, relative to their substrates. Ectomycorrhizal could be distinguished on the basis δ signatures. Although there high variability isotopic composition following isotope‐ enrichment factors (ε, mean±SD) substrates...
Quantifying global patterns of terrestrial nitrogen (N) cycling is central to predicting future primary productivity, carbon sequestration, nutrient fluxes aquatic systems, and climate forcing. With limited direct measures soil N at the scale, syntheses (15)N:(14)N ratio organic matter across gradients provide key insights into understanding cycling. In synthesizing data from over 6000 samples, we show strong relationships among isotopes, mean annual temperature (MAT), precipitation (MAP),...
Abstract. Nitric acid (HNO3) or nitrate (NO3−) is the dominant sink for reactive nitrogen oxides (NOx = NO + NO2) in atmosphere. In many Chinese cities, HNO3 becoming a significant contributor to deposition. present study, we measured (N) and oxygen (O) isotopic composition of NO3− 113 precipitation samples collected from Guangzhou City southern China over two-year period (2008 2009). We attempted better understand spatial seasonal variability atmospheric NOx sources formation pathways this...
Nitrous oxide (N 2 O) is an important atmospheric greenhouse gas and involved in stratospheric ozone depletion. Analysis of the isotopomer ratios N O (i.e., intramolecular distribution 15 within linear NNO molecule conventional isotope ratios) can elucidate mechanisms production destruction. We analyzed dissolved at a site eastern tropical North Pacific (ETNP) Gulf California (GOC). At these sites, flux to atmosphere extremely high but denitrification activity oxygen minimum zone (OMZ) also...
[1] Isotopomer ratios of N2O (bulk nitrogen and oxygen isotope ratios, δ15Nbulk δ18O, intramolecular 15N site preference, SP) are useful parameters that characterize sources this greenhouse gas also provide insight into production consumption mechanisms. We measured isotopomer emitted from typical Japanese agricultural soils (Fluvisols Andisols) planted with rice, wheat, soybean, vegetables, treated synthetic (urea or ammonium) organic (poultry manure) fertilizers. The results were analyzed...
Significance How terrestrial plants use N and respond to soil loading is central evaluating predicting changing ecosystem structure function with climate warming pollution. Here, evidence from NO 3 − in plant tissues has uncovered the uptake assimilation of by Arctic tundra plants, which long been assumed negligible. Soil contributed about one-third bulk used northern Alaska. Accordingly, importance for should be considered future studies on C cycling ecosystems where sequestration strongly...
Abstract Increased deposition of reactive atmospheric N has resulted in the nitrogen saturation many forested catchments worldwide. Isotope‐based studies from multiple forest sites report low proportions (mean = ∼10%) unprocessed nitrate streams during baseflow, regardless or export rates. Given similar baseflow across a variety and types, it is important to address postdepositional drivers processes that affect transport fate within catchments. In meta‐analysis stable isotope‐based studies,...
Nitrification has been believed to be performed only by autotrophic ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing (NOB) until the recent discovery of archaea (AOA). Meanwhile, it questioned whether AOB are significantly responsible for NH(3) oxidation in acidic forest soils. Here, we investigated nitrifying communities their activity highly acidified soils three subtropical forests southern China that had received chronic high atmospheric N deposition. Nitrifying were analyzed using...
AbstractData have been compiled from published sources on nitrogen (N) fluxes in precipitation, throughfall, and leaching 69 forest ecosystems at 50 sites throughout China, to examine a national level: (1) N input precipitation (2) how changes after the interaction with canopy, (3) whether increases increasing deposition and, if so, what extent. The of dissolved inorganic (DIN) ranged 2.6 48.2 kg ha−1 year−1, an average 16.6 year−1. Ammonium was dominant form most sites, accounting for,...
The goal of this study was to elucidate the mechanisms nitrous oxide (N2O) production from a bioreactor for partial nitrification (PN). Ammonia-oxidizing bacteria (AOB) enriched sequencing batch reactor (SBR) were subjected N2O pathway tests. test initiated by supplying an inorganic medium ensure initial NH4+-N concentration 160 mg-N/L, followed 15NO2- (20 mg-N/L) and dual 15NH2OH (each 17 spikings quantify isotopologs gaseous (44N2O, 45N2O, 46N2O). boosted spiking, causing exponential...
There has been much progress in understanding the nitrogen cycle oceanic waters including recent identification of ammonia-oxidizing archaea and anaerobic ammonia oxidizing (anammox) bacteria, comprehensive estimation abundance activity these microbial populations. However, compared with waters, there are fewer studies concerning benthic cycle. To further elucidate dynamic deep-sea sediments, a sediment core obtained from Ogasawara Trench at water depth 9760 m was analysed this study. The...
We tested the ecosystem functions of microbial diversity with a focus on ammonification (involving diverse taxa) and nitrification only specialized in forest nitrogen cycling. This study was conducted slope, which soil environment plant growth gradually changed. measured gross net rates nitrification, abundance predicted ammonifiers nitrifiers, their community compositions soils. The did not change along environmental gradient, leading to no significant rate. On other hand, nitrifiers rate...
Nitrification is a crucial step in ecosystem nitrogen (N) cycling, but scaling up from plot-based measurements of gross nitrification to catchments difficult. Here, we employed newly developed method which the oxygen isotope anomaly (Δ17O) nitrate (NO3–) used as natural tracer quantify situ catchment-scale rate (GNR) for temperate forest 2014 2017 northeastern China. The annual GNR ranged 71 120 kg N ha–1 yr–1 (average 94 ± 10 yr–1) over 4 years this forest. This result and high stream NO3–...
Atmospheric nitrogen (N) fixation is a key N input to arctic ecosystems, but relatively few estimates of annual N-fixation rates are available. We measured plant-soil cores by the acetylene reduction technique at different topographic positions in an upland tundra watershed, Imnavait Creek, through two growing seasons order evaluate spatial and temporal variation N-fixation. also examined effects light temperature on estimate surface soil this watershed using field meteorological data....