[go: up one dir, main page]

Academia.eduAcademia.edu
Jpn. J. Limnol., 52, 4, 263-281, 1991 Review Gas Exchange in Ecosystems: Framework Eitaro and WADA, John A. LEE, William Case Studies Makoto KIMURA, Isao S. REEBURGH, Jose G. TUNDISI, Tadashi Takahito YOSHIOKA,and Margret KOIKE, YOSHINARI, M. I. VAN VUUREN Abstract This report is an extended summary of the symposium on "Carbon and Nitrogen Cycles in the Biosphere and Geosphere" in INTECOL '90 held at Yokohama on 28 August 1990. The general ideas and aspects of nitrogen and carbon dynamics in ecosystems are described along with atmospheric nitrogen biogenic gases such as carbon dioxide, methane, molecular Increases of the radiatively active gas concentrations atmosphere are described ments and food demand. supply, and behavior of nitrogen and nitrous oxide. (CO2, CH4, and N2,O) in the in connection with human impacts such as energy The increase in atmosheric carbon dioxide has been caused by fossil fuel combustion, that is, a man-made C-O-Fe-S cycle. Increase in crop production require- short circuit between atmosphere and dominates the fluxes of mineralization processes of organic matter both in aerobic and anaerobic conditions, resulting in the enhancement of methane and nitrous oxide production in the whole biosphere. Several current efforts to investigate atmosphere-biosphere interactions are schematically summarized for site specific phenomenon such as plant-soil associations and for some representative ecosystems (heathland, rice rhizosphere, tundra and taiga, lake, tropical reservoir, Key words: Oxygen 1. coastal and estuarine cycle, human impact, system, and global atmospheric N2O cycle). deposition, biogenic gases biochemical pathways that transport the bioelement directly between the atmosphere and the Introduction One among the principal prerequisites for the evolution and survival of terrestrial life is the biosphere. cycling of bioelements 3.5 billion under moderate climate. appearance The primary highlight of photosynthetic years ago. was the organisms some Two biochemical path- Atmospheric and water circulations play a major part in the operation of biogeochemical ways, fixation of carbon tion of molecular oxygen, cycling sions for the cycling of matter and the evolution on the Earth's ment such as hydrogen, surface. carbon, Each bioele- nitrogen, and of the atmoshere dioxide and producprovided new dimen- as known in the present bio- oxygen completes its biogeochemical cycle as being major or minor components in the atmo- sphere. initiated sphere MARSHALL,1964) and the framework of biogeo- chemical and sulfur genesis and the circulating of life, living * Symposium organizer water. organisms After evolved the new The increase in atmospheric oxygen some 2 billion years ago (BERKNERand cycling of carbon, nitrogen, 264WADA , LEE, KIMURA, KOIKE, REEBURGH, TUNDISI, YOSIIINARI, YOSHIOKA and was completed by the evolution oxidation-reduction ments. Evolution of microbial pathways of these eleof the biosphere has then been closely associated with these cycles. The C-O-Fe-S the partial cooperating geological cycle keeps pressure of atmospheric oxygen at its present level (GARRELSet al., 1976). There is a considerable interest in the level of the partial pressure of atmospheric carbon dioxide an during the Precambrian apparent period contradiction due to between the certainly introduces VAN VUUREN the increasing of oxidation-reduction fields, wetlands, occurrence boundaries and aquatic in cultivated ecosystems. The anthropogenic impacts are manifest as two manmade short circuits between atmospheric carbon dioxide and the geological carbon cycle (fossil fuel combustion) and between atmospheric dinitrogen and the short term biogeochemical tion). nitrogen In this report cycling (artificial N2 fixa- the global cycling of bioele- continued existence of life and the early, faint Sun that is predicted by the present models of ments is summarized biosphere interactions to address atmospherewith emphasis on current solar global environmental deposition, ecosystem problems. processes, evolution (KUHN and KASTING, 1983; WALKER,1983; NEWMANand ROOD,1977). In this context, carbon isotopic studies of Precambrian rocks appear to provide a piece of biogeochemical evidence; the atmospheric carbon dioxide content was two orders of magnitude higher during most of the Precambrian than the consumption presented involving lacustrine even today. At present the Earth's surface production of gases are for several representative ecosystems forests, tundra and taiga systems, environments, coastal and estuary areas, and open oceans. present level (MIZUTANIand WADA, 1985). Our atmosphere is the product of the past 3.8 billion years of life and the biosphere has lived in a global green house during the continuous existence of life. The Earth's greenhouse effect has changed over geologic time and is changing and Atmospheric and biogenic 2. Biogeochemical From the biogeochemical cycles standpoint, bioele- ments are characterized as having stable forms of molecules in three phases such as gas, liquid and solid. late each This fact makes it possible to circuelement through biosphere, hydros- temperature is raised about 35'C above what it would be if no radiatively active gases were phere, and atmosphere. evolution of biochemical present (HILEMAN,1989). Since the pioneering work gaseous substrates and products plays a decisive role in biogeochemical cycling in the pres- surements of atmospheric centration at Mauna of monthly carbon dioxide Loa by Charles meacon- KEELING In this context, the reactions concerning ent biosphere. These biochemical processes are CO, and N2 fixation, and N2, N2O, CH, and (KEELING et al., 1976), considerable attention has been paid to the increases in atmospheric production. In the sphere, practical operation deposition ing from accepted to have evolved some 2 billion years ago when oxygen partial pressure was raised up which and radiatively active gases originatexpanding anthropogenic impacts, principally result from the increasing pressure of human population and can be characterized in terms of energy requirements and food demand. For example, carbon dioxide and NOX generally combustion, while originate methane from fossil fuel and nitrous oxdie are byproducts or end products in the process of microbial decomposition of organic matter. Global dynamics are thus closely of the latter two compounds correlated with agricultural crop production of which expanding increase H,S to 10-2 of PAL The (present accumulation history of the bio- of these processes atmospheric of atmospheric is level). oxgen is generally accepted by the occurrence of continental "red beds" (JUNGE et al., 1975). After the increase in PD, in the atmosphere, operations of all biological mary governed processes have been pri- by the existence of molecular oxygen in the atmosphere. At present molecular oxygen is the most efficient electron acceptor in our respiratory and also determines energy yielding the stability system of chemical Gas Exchange forms of tion other reactions. terminal In on cycles in the present the bioelements can the following Turn of oxygen time places a biogeochemical (Fig. oxygen in be 1). the other expressed atmospheric time atmosphere as oxygen as a by amount annual rate Where the in molecular of oxygen in the 02 in the one equivalents molar 02=1-0 nitrogen=4/3 can molar molar be car- Fee-=1/2 in kinds terms of of decomposition biosphere. production Fig. 1. turn into Organic such organic over matter time gaseous Oxygen grass, via crop, and SVENSSON (1976), classi- in annual to leaf, The values can the be on biogenic used for annual Nitrification primary formed tion of the accumulation molecular gas productions. are all equivalent and GARRELS et al., (1990) are also included. the (1976). rate production to molar O2 Data and of this 105 from was estimated was nitrate. BOLIN time of al., been 1979) If 103 this cycle, in The rocks which be net organics, values of fluxes are SODERLUNDand total see text. has produc- estimated sedimentary by assuming we oxygen OHTAKE (1978), and BOUWMAN Details, for then cycle. sedimentary after we years accumulated C-O-Fe-S in can of (38•~1018/320 pool Revised et Molecular oxygen in pool 1977), years has Numerical indicated inventory. group. of organic large RAYNER, geological by not C, over atmosphere organic accounts years. second carbon turn for largest molecular process are the (JENKINSON through been primary cycle with emphasis 1012 mole•yr-1. nitrogen be respect products matter as can with the over decomposed of dissolved atom average estimate ƒÑ(O2) this peat organic can in and (320•~1015g pool is matter, constitute this turn almost amounts organic global an short produced of oceans, •~ 1015•~10-3) sulfur. Several in 1, these a ecosystems (38•~1018/17,000•~1012) soil adopt molar matter 2•~103 the many equivalent ca. in of In The ƒÑ(O2) Fig. atmosphere/ year. organic Although a process], following molar consuming organics of practice; bon=2/5 the by matter of representative one all for turn- defined as of oxygen. cycles (ƒÑ, year) =[total molar regarded equation: over used oxidation-reduc- biosphere of time sense, cooperating cooperation over in this the The of fied bioelements 265 in Ecosystems inorganic from as 266 one WADA, LEE, KIMURA, KOIKE, REEBURGH, TUNDISI, YOSHINARI, YOSIIIOKA and molar buried molecular carbon oxygen. partitioning of between free reservoir The ƒÑ(O2) by bond pool as cycle a only the estimated from primary We tion of the total N•yr-1 equals to nitrate produced porated its here is (WADA to and HATTORI, this then 018/5•~1014) ca. r(O2) becomes (Fig. ca. 105 One way to outline past is to compare of factors with primary in atmospheric gases. Since impacts the changes N2 plus (38 were The ppm) is every year lower resulting CH, plus products, N2O and impacts gases (CO2, CH4, after increasing the et 1976, percentage fule War II. CO, (340 than 1 ppm 1979), annual (Fig. fossil the pro- the more al., for N2O) World of population one part billion nearly the equal which is growth 3) rate (OFITAKE, burning 1978). annually remains The lower the atmosphere adds the in the (PEARMAN 1990). Each year, Main of (CICERONE (ƒÑ(O2)). time of of tion. these organic and are closely Consequently, in level the million the more are the to increase lands and the burning) The the than wet (biomass 1988). , tons atmosphere of fermentation related of BOUWMAN 50 matter , changing methane OREMLAND, as forest 1988; increase intestinal in such the is additional of CO2 gases, remains CO2 ocean. FRASER, annual of harvested the car- 1989). growth of house an sources fields, pyrolysis of and COQ of population sinks atmosphere methane an rate of green fastest released the action biogenic tons increasing of vege- the (HILEMAN, regrowth buffering from billion atmosphere than atmosphere. Of 2.5 variety biota, paddy residence the a the generated about in from 1%. is to destruction. percentage the CO, amount annually, bon of soil representing on tons and released biogenic of A six tation increases of in the change of oxygen (FFC)•¨CO2 plus (KEELING present, methane atmospheric require(FD), combustion burning currently human Of illustration following demand concentration than and Schematic Food accelerated present terrestrial 2. the (PG)•¨Energy plus active results Fig. anthropogenic by CH4 duction the during temporal concentrations the expanding The impacts human the biosphere. anthropogenic some recent vari- general production•¨Decomposable radiatively of anthropogenic present matter•¨CO2 plus 2). Expanding expect all ER+FD•¨Deforestation+Cattle•¨CO2 At 3. the fuel organic The incor- years change Aerosol, plus of by not qualitative growth FD•¨Crop iv) which be the among represented (ER) plus iii) part could be with could variation along can ER•¨Fossil be 2•~1014g 1991), process ii) in annual A denitrification. nitrification be in Population utiliza- The the we expect occur ment (OHTAKE, mole O2•yr-1. in into uptake. i) global nitrate of cycles, processes. can ratio 60% estimated 500•~1012 events impacts denitrifica- during C/N ca. nitrogen rate atom uptake and assume nitrification •~1 nitrogen main atmo- rate the could years cycle and but interlinked of figures ables nitrogen oxygen nitrification production 1978). the always part similar the the are other to nitrogen, The in trends stability in nitrification maximum 0.05: system 1990). 107 the exists with bound is ca. of component. of The is molecular cooperates the WADA, process nitrogen major processes tion. of of of the 02 present 1975; Because triple sphere and at al., this mole that produced SO42-) et (38•~1018/2.5•~1012). the one accepted 02) plus value largest now (atmospheric (SCHIDLOWSKI of is photosynthetically (Fe2O3 0.95 produces It VAN VUUREN last crop in three produc- the meth- , Gas Fig. 3. Temporal variations production, ane concentration radiatively production. with the popula- 267 in Ecosystems active gases, exhibits a 0.3% annual which is not as fast as methane, from 280 ppb at the turn of this century methane modes rising The detailed microbial, ecological to 303 chemical studies exchange time is rather long (ca. 100 years) with methane (ca. 10 years). sources of the increased might matter tons of N2O into the atmoturn oxide over as compared The major nitrous oxide are fertil- human of ecosystems to elucidate activity on are shematically point, we would like to emphasize sion to approach this problems. a new dimenStable iso- sphere biological hydroxyl radicals, gas illus- trated in Figure 4 with emphasis on fossil fuel combustion and crop production. At this topes of light elements such as carbon nitrogen undergo fractionation in chemical with de- and biogeo- ized soils, and biomass and fossil fuel burning. Most of the methane is removed from the tropoby oxidation from during in ecosystems. will be required of result of production of organic tion of 5 million Its tropospheric rice crop composition this point. Perturbations each year. population, and nitrous ppb at present (RASMUSSENand KHALIL, 1986; BOUWMAN,1990). This results from the injecsphere human CFCS: chlorofluorocarbons. the different tion growth. Nitrous oxide increase of atmospheric and fertilizer is correlated Exchange reactions. Biogenic and and materials in while the only known atmospheric sink for NZO is its breakdown to NO in the stratosphere by global cycles of the light elements have their own isotopic composition, so-called "dynamic ultraviolet light stable Differences in the annual increase (YOSHIDAand MATSUO, 1983). rate between isotope a fluctuation (SI) finger print". of a molecule's In principle, isotope ratios 268 WADA, LEE, KIMURA, KOIKE, REEBURGH, TUNDISI, YOSIIINARI, YOSHIOKA and Fig. 4. Schematic illustration of the perturbation of carbon and nitrogen VAN VUUREN cyclings by the human impact. provides information about its origin, pathways, and the reaction mechanisms concerning its formation. On a macroscopic level , SI for nitrate chemical markedly Northern Hemisphere. in many deposition show can provide two and four fold depending solve biogeochemical phenomena involving transport of organic A., unpublished). In many near pristine turbation in an ecosystem. to matter and per- For example, the regions For example of an ecosystem a key structure increased of the estimates increases between on location environments (LEE, J . nitrogen supply can be shown to be a major determinant CO2 increase in the atmosphere and its carbon isotope ratio follow a single mixing (KEELINGet of plant growth, content of plant al., 1979) and every one ppm of the CO, added sition and mineralization processes. increases in combined nitrogen deposition to the atmosphere introduces the ratio changes of about -0.02 %o (MOOK et al ., 1983). Several examples will be shown in the following case studies. 4. combined atmosphere widespread Evidence Atmospheric ecosystem During the nitrogen nitrogen from emissions. Century deposition the atmosphere in the nitrogen may be having decompoThus from marked and effects on ecological processes. is now accumulating to support the view that terrestrial ecosystems are being perturbed markedly by anthropogenic nitrogen supply and process the Twentieth and increases litter can accelerate of has These and heathland deposition include ecosystems represents ombrotrophic where an important mires atmospheric source of Gas Exchange bioelement. In the most polluted ecosystems can be shown regions these to be 269 in Ecosystems (Beizexose, atmospheric adversely 1990). Nowadays, the increased deposition of nitrogen accelerates affected by atmospheric nitrogen deposition. However as nitrogen accumulates in plants and the succession soil as Molinia organic matter the change in ecosystems to an alteration potential for latent which are less susceptible (Plate there has grasses such 2). in nitrogen nant, the nitrogen potential the importance. availability created species cycle is strongly itself. The affected above- and by below- ground biomass production and the amount of litter is greater in Molinia as compared to Erica 5. 5-1. cacrulea As a result, of perennial suitable conditions for the spread of Molinia. However, once this species has become domi- or in less polluted regions becomes more pronounced. This change is difficult to assess, but and increasing increase The increase in the aerial supply of elements may of considerable process. been a strong Case studies The impact upon or Calluna of dominant nitrogen cycles plant in species heathland ecosystems (M. I. MARGRET) Heathlands in the Netherlands have dominated heathlands (Aioers and BERENOSE,1989; Ar;Rrrs et al., 1989). Molinia litter concentration, immobilisation devel- has a relatively Although low nitrogen which leads to a net nitrogen in the first stage of decomposi- oped on sandy soils and used to be dominated tion, by ericaceous shrubs Erica (Plate produced by Erica or Calluna due to its relatively low lignin content. As a consequence, a tetralix succession, nitrogen like Calluna 1). vulgaris or At the beginning of supply through tion is very low in these ecosystems. mineraliza- it decomposes greater through However, much ing in the soil organic to influence higher nitrogen mineralization rates Plate 1. Erica the dominant lctralix. than litter amount of nitrogen will be supplied mineralization, instead of accumulat- the amount of soil organic matter increases by the input of plant litter, which gradually leads that faster layer. plant It was concluded species on the rate of nitrogen have a clear cycling in these 270 WAnA. LjAc, KIMURA, KOIKE, REEBURGH,TUNDISI, Plate 2. Molinia ecosystems. 5-2. Production of biogenic gases in rice rhizospheres and their transfer to the atmosphere (M. KIMURA) The fact that paddy rice grows in the submerged (reduced) environment characterizes the kinds and amounts of biogenic gases produced in the rhizosphere and their transfer to the atmosphere. Contrary to the general understanding, the rice rhizosphere is not always oxidative. It becomes reduced from the maximum tillering (MT-) stage in growth, and the biogenic gases are produced sequentially as growth proceeds; the production of CO,, and N,O and N, by denitrification occur in the early growth stage and the denitrification terminates before the MT-stage. Hydrogen production is observed around the MT-stage. Methane production begins after that. The root system consists of roots of different ages, and old roots produce the reducing environment where H, and CH, production and SO,'- reduction occur. Hydrogen is produced in/on the roots, and the main sites of CH4 YOSHINARI, YOSHIOKA and VAN VIIREN caerulea. production rhizosphere and SO42- reduction are soil. Hydrogen produced roots is selectively utilized in the in/on for sulfate reduction in the rhizosphere. Thus, the production different of each biogenic to one another is controlled gas is in time and space, and by the growth stage of paddy rice (CICERONEand SHETTER, 1981; CICERONEet al., 1983; DE BONTet al., 1978; HOLZAPFEL-PSCHORN et al., 1986; HOLZAPFUL-PSCHORN and SEILER, 1986; MINAMIand YAGI, 1988; SEILERet al., 1984). The transfer of CO, and CII, produced in the rhizosphere is different due to the difference of solubility to water (Fig. 5). CO2 is absorbed by rice roots, and transferred to the shoot and then to the atmosphere (HR.ucHI et al., 1984; WAUA et al., 1983; YOKOYAMA and WADA, 1983). Some portion of absorbed CO, is photosynthesized by the shoots. The mechanisms of transfer of CO, through plants is still controversial. consider it to be associated transpiration, and otheres Some scientists with the flow of consider it to occur by diffusion in gaseous state through intercellular spaces of the aerenchyma in the root Gas Exchange Fig. 5. Schematic t ransfer cortex. CO2 remaining subsoil illustration showing production 271 in Ecosystems of biogenic gases in rice rhizoshere be present in bubbles, and their to the atmosphere. in the soil is carried to the in the form of HCO3- with the move- atmosphere evidence partly that by and it is carried ebullition, transfers occur but mainly to the there is through ment of leaching water. Rice plants are known to influence this CO2 leaching (TSUCHIYA root-shootpathway(INUBUSHI et al.,11989). et al., 1984). paddies Due to the low solubility of methane it is not leached downward. in water, It is considered to The emission were rates of methane not altered by cutting from rice the rice plants above the water level. So the transfer is considered to be due to the gaseous diffusion 272 WADA, LEE, KIMURA, KOIKE, REEBURGH, TUNDISI, YOSHINARI, YOSHIOKA and not due to the transpiration. The main route of methane emission is considered to be through old roots to the shoots. Some portion of methane may be oxidized on its way to the atmosphere. 5-3. The role of tundra and taiga systems in the global methane budget (W. S. REEBURGH and S. C. WHALEN) Tundra and boreal forest soils contain some 30% of the terrestrial soil carbon reservoir (Pose, et al., 1982). A large fraction of this soil carbon is immobilized in permafrost and peat. This soil carbon reservoir could be susceptible to biogeochemical conversion to CO, and CH, under warmer, wetter climates. Both of these gases are radiatively active, and could be responsible for a positive climate feedback . We evaluated the importance of tundra and taiga systems in the present global CH, budget and studied processes important in modulating emissions under present and modified climates with weekly measurements of CH, flux at a set of permanent sites (WHALENand REEBURGH, 1988, 1990a). Our CH, flux time series at tundra sites in the University of Alaska Arboretum covers over 3.5 years and indicates that water table level, transport by vascular plants and microbial oxidation at the water table are important in modulating tundra CH, emissions. Emissions of CH, essentially cease during frozen periods. Our study at permanent taiga sites involves one set of flux measurement in October, 1989, and weekly measurement from May to October 1990. All taiga sites except those adjacent a river consumed atmospheric methane, indicating that these soils are sink for atomspheric CH4. Integrated annual emissions from the seasonal time series measurements and results from a detailed survey along the Trans Alaska Pipeline Haul Road lead to independent estimates of the global tundra CH, flux of 19-33 and 38 Tg•yr-1, respectively (WHALENand REEBURGH, 1990b; REEBURGH and WHALEN , 1990). The road transect estimate for the global taiga CH, contribution is 15 Tg•yr -1. Microbial oxidation of methane is an important modulator of tundra fluxes (REEBURGH and WHALEN, The 1990; WHALEN process the is water at in rates rapidly tion is moist the suggests control serve as a the for occurs Methane oxida- more important Preliminary process methane sink but equilibrate conditions. that tundra adjacent which become drier 1990b). region soils, soils, to warmer, work the atmosphere. expected under REEBURGH, to waterlogged in with and restricted table high VAN VUUREN could not emissions, only but atmospheric also methane (Fig. 6). 5-4. Metabolism of lacustrine Aquatic ecosystems ponents ratios, tion on the may tion of the content ments biogenic will with the gas the biological Stable shallow km2; max. spheric CO2, pH values and the at al., by bloom S13C,,,c value chemical kinetic be CO2 pleted CO2 processes seem assimilation contribute during 10 water photo- conditions affected CO2 invasion of the from negative with supply , by large the of equi13C de- decomposition also the in phytoplankton, and fractionation about intense these the respiration lakes, rise the largely The season CO2 compared to the of shows exchange. from Since often of which fractionation, librium summer forming may atmo- eutrophic Under enhancement atmosphere, the of those with In because 13.3 than equilibrium in ina eutro- area, lower waters low Microcystis. with dissolved Suwa, (surface pressure as the the vary of were 1990). partial synthesis of because Lake Japan surface quite biological largely in m), waters of becomes CD,G. in 6.8 et the processes ratios particularly (TAKAHASHI environinterations depth. lake for composi- by by lakes (ƒÂ13CDIC) depth, observed only also isotope carbon phic the water and step. isotope interface, in carbon organic such but iso- fractiona- lacustrine consumption air-water with with stable important the in not activities and activities aqueous most and governed and below time the atmosphere, production com- isotope gases be gaseous between be in YOSHIOKA) their equilibrium exchange phases However, biological Concerning gas gaseous CO2 from atmosphere. tope components (T. exchange resulting the gaseous ecosystems to the low 813 photosynthetic summer season in Gas Exchange 273 in Ecosystems Waterlogged-Saturated Fig. 6a. Schematic solis. diagram Oxidation boundary. Methane showing occurs Transport fluxes controls on methane in the vicinity of methane to the atmosphere Fig. 6b. Schematic diagram occurs throughout lar diffusion. fast relative atmospheric showing are positive controls to biological methane soil interval consumption in waterlogged table, by aqueous which phase and saturated is the oxic: anoxic molecular diffusion. (REEBURGH and WHALEN, 1990). Soils on methane the moist soil interval. The moist oxidation of the water is controlled Moist Soils oxidation Transport equilibrates rates. in moist is controlled soils. with the atmosphere Moist (REEBURGH and WHALEN, 1990). soils are Oxidation by gas phase capable molecu- at rates that are of consuming 274WADA Lake in , LEE, KruuRA, Suwa the was These zone duration of Suwa, the are ecosystem tion process spp. Since shows by flow can be In of to be a et al., N20 1988a, the ƒÂ15N than that the remaining very of NO3- the N03 in value YOSHIOKA et suggested that emit the in whole al., to N2O seemed oxic 1988). the al., These period Fig. 7. of and and Lake Schematic of producing opportunities Newly constructed had of in- aquatic eco- hydroelectric for assessing inter- factors and dams in the Amazon have a large flooded forest area where rapid mineralization of organics can take place under relatively high temperatures. Accumulation of nitrogen N2 ratios in many part of during recent past actions between environmental human communities. observations N20 isotope (J. G. TUNDISIand E. WADA) the purpose vide excellent lower submitted; light as be hypolinion et isotopically atmosphere overturn (YOH showed to on power and water supply. These reservoirs in Brazil are distributed in a range of geographic regions with diverse human impacts and pro- m), hypolimnion anoxic (WADA with Japan regard- survey depend in hypolimnion, (NO3-, N2O and so on) might The number of reservoirs tropical forests has increased 29.8 are The nitrogen nitrogen systems , 7). processes period also depend on these factors. 5-5. Gas exchange in tropical (%0) in depth, denitrification of organic ecosystem lake max. Preliminary value high 15N might mesotrophic the overturn of these processes will cease. the process (Fig. during N2O lake the extent of the anoxic layer, and the timing of whole overturn of lake, when denitrification fixa- value lake accumulating b). this values km2; and the in the activities Anabaena by nitrogen surface the long into algae, the Lake N2 low ƒÂ15N 1.4 nitrification ed biological the ƒÂ15N Kizaki, area, both introduced nitrogen new by he in the blue-green the Lake (surface During was characteristic to in condition fixed traced due Suwa. through the the Lake nitrogen the negligible. Microcystis VAN VUUREN The amounts of hypolimnetic N2 and released to the atmosphere across the enrichment be originally by of 13C to N-deficient new lake the seemed photosynthesis euphotic ing small, DIC phenomena intense that very remaining KOIKE, REEDURGII, TUNDISI, YOSHINARI, YOSIIIOKA and tree leavesand microalgaeand denseunder- dur- Kizaki illustration . water vegetation of gas exchange produce in Lake Suwa . microanaerobic sites Gas Exchange near the large bottom methane The the basin. It is Rondonia. km km with reservoir third of located the of huge amounts trial plants long depth values values of nitrogen dam of processes. sulfide-like A compounds site such at as this dam the was time (Fig. construction, Fig. 8. easily 8). sediments of with - hydrogen- Thus at human deforestation Schematic extent. In coastal detected nitrogen metabolism, have been Denitrification is the lar- reservoir. release of (I. KoIKE) inflow of nutrients from region, microbial activ- by nitrification smell and estuar- on 615N reservoir in coastal effects last for gest gas evolving process within the nitrogen cycle in the biosphere and is responsible for returning fixed nitrogen to the nitrogen gas phytoplanhigh the of occurrence denitrification by Such commonly in both the water column and the of near-shore environments to a considerable isotope caused showed areas ities, including gases (POM) was suggesting upper of stimulated sediments low ƒÂ13C CO, POM +13%, subsequent This mineralized surface from matter at least 3 years. 5-6. Gas production of construction. carbon recorded. ine environments terres- bubble were Due to the increasing the populated coastal the loading dramatically -37%0. of The at construction and algae by dam construction deeper from and nitrogen of km2. the the dam after organic to 1300 and caused to anaerobic materials exhibited recycling m the aquatic Velho, width of of year Particulate Port materials by for down 35 became a water extends area organic half of gases such as CO, CH,, N, and N,O. Consequently, s15N of the remaining available nitrogen became higher and low s13C values for October a maximum is biological kton. impact and Amazon west because of fillter km flooded reservoir collected GFC the (TUNDIsI in the has flooded studies. the high reservoir and total 1989, dam, were 100 construction July, in Samuel a time the (cutting and burning of forest), and sand mining with subsequent burial of plant materials in downstream areas, enhanced the release of where with constructed dam maximum layers In reservoir, emitted (>30%) The 150 The the are biogenic Samuel is 20 of bubbles unpublished). 1988 over of concentrations WADA, a surface amount 275 in Ecosystems illustration environments, tion. Recent observations rence of a close coupling and denitrification with the Although coastal the layer of indicating the occurbetween nitrification in sediments are consistent above view (NisHio et production of nitrogen environments nitrogen of gas exchange the surface is the most active site of denitrifica- budget in Samuel al., 1983). gas from has a significant of the dam. system, effect on evolved 276WADA nitrogen long , LEE, KIMURA, KOIKE, REEBURGH, TUNDISI, YOSHINARI, YOSHIOKA and VAN VUUREN gas term is rather changes hardly be detected spheric reservoir. Both nitrifying the capacity near shore nitrous Fig. atmo- bacteria have is mainly nitrogen waters 9. large of the and denitrifying of microbial coastal oxide production. In of as well activity. sites ments. as oxygen for nitrous in oxide middle of sediments and the effect side of bottom right sediments during irrigation of nitrifica- (KOIKE and SORENSEN, 1988; SuMI and KOIKE,1990; KOIKE, 1990). Figure 9 shows the possible micro sites in coastal of waters, where close coupling is mainly nitrous of responsible for oxide, a potent source the evolution and tion in the atmosphere. nitrogen column biological column activity gas evolution indicates vertical processes indicates of benthic on the the injection animals in coastal and profiles profiles of (ALLER of oxygen (JORGENSEN and estuarine major of of ozone destruc- of nitrous the the the process nitrification and denitrification is to proceed. Both microbial nitrification and denitrification to the Eutrophication by accelerating tion and denitrification by the supply production Figure oxide can the concentration controlled stimulates Micro and even because for nitrous oxide inert content environments, of inorganic sites chemically in atmospheric environ oxidants , 1982). Figure (Umole•El-1) REVSBECH in in into , 1985). Gas 5-7. Exchange Stable isotope composition in nitrous oxide from various sources (T. it YOSHINARI). duction is and important biomass N20 concentration For ples the fossil burning, and N2O the and were of quartz sealed Based tive isotope values can The and sink gas N20 in in from the 450•Ž and N20, and for the 24 hr The 15 CO2 data respec- from literature, 10) global shows strengths the ranges land and ocean. the a qualitaand (Fig. source in spectrometry. biogeochemistry diagram of atmospheric was CO, 1990). N2 isotope oceanic of N20 in the atmosphere, different method and mass N20 described. and N2 by be sam- Subsequently, at ratios N20 few modified carbon of schematic a and the chromatography determined and nitrogen (YosIIINARI, 18O/16O the in the to tube study aspect terrestrial of the sources and N2O, (1983). graphitic on present ous other environments. diagram envi- of both and by in budget and oxygen oceanic of quantitatively presence is to establish a broad database of the isotope fingerprint of N20 in the atmosphere and vari- nitrogen pro- nitrification combustion by MATSUO purified tively, Schematic relative N2O photolysis of collected and N/14N Fig. 10. as and fuel the atmosphere YOSHIDA product of biological nitrification. The use of the stable isotope signature of N20 as a tracer this effort, soil composition were converted Through the determination gas is one of key elements in the nitrogen cycle on the Earth since it is an intermediate of biological denitrification as well as the by- promises to provide the information which cannot be obtained by the conventional approaches. The long-term goal of this study the of such in isotope in of into processes decomposition, the o xygen expanding Also, this insight troposphere. sources processes. and upper at the rate of gain different denitrification approximately 0.2-0.4% annually (BoUWMAN, 1990) is attributed to release mainly due to anthropogenic to of ronments, and a greenhouse gas, which contributes to the increase of average surface temperature of the Earth by absorption of infrared radiation. The increase of tropospheric hoped importance Nitrous oxide (N2O) in the atmosphere is a natural source of stratospheric NO, which is in ozone chemistry, 277 in Ecosystems of of (1) N20 278 WADA, LEE, KIMURA, KOIKE, REEBURGH, TUNDISI, YOSHINARI, YOSHIOKA and and the stratospheric sink, (2) the amount of N2O reserved in each environment, and (3) the range of nitrogen and oxygen isotope values of N2O in the troposphere, land and ocean. The source strengths of N2O from the land and ocean, 8-13 and 4-6 Tg•yr-1, respectively, were derived from the following consideration. The estimated range of land origin N2O, which includes the fluxes of N2O from microbial processes in the soil, fossil fuel combustion and biomass burning, was derived from the addition of the stratospheric sink strength [11 Tg•yr-1 (CICERONE, 1989)] and annual rate of increase [3-6 Tg•yr-1 (WEISS, 1981; RASMUSSEN and KHALIL, 1986)], less the total flux of oceanic N2O , 4-6 Tg•yr-1. The latter was estimated from the results of recent studies in the open ocean (CLINEet al., 1987; BUTLER et al., 1989) and the contribution from the coastal environments, which was assumed to be as much as the amount of N2O from the open ocean. The range of the nitrogen and oxygen isotope values of N2O shown in this figure were derived from the literature (KIM and CRAIG, 1990; WAHLENand YOSHINARI, 1985; YOSHIDAand MATSUO, 1983; YOSHIDA et al., 1984; YOSHIDA et al., 1989;YOSHINARI and WAHLEN, 1985) and from the present study. Since various sources that produce N2O by different mechanisms o bined, the range for the N2O isotope values from the land shown in this diagram is very wide. 摘 要 生 態 系 に お け る ガ ス 交 換: そ の 全 体 像 とケ ー ス ス タデ ィ この 報 文 は,1990年8月28日 横 浜 市 で開 催 さ れ た 国 際 生 態 学 会 の シ ン ポ ジ ウ ム"生 物 圏 ・大 気 圏 の 炭 素 ・窒 素 循 環"で 発 表 され た 論 文 を表 題 の 線 に 沿 っ て ま と め た も の で あ る。 先 ず 大 気 降 下 窒 素 化 合 物 の 生 態 系 へ の 供 給 や 炭 酸 ガ ス ・メ タ ン ・ 窒 素 ガ ス ・亜 酸 化 窒 素 ガ ス の 生 態 系 か ら の 発 生 に つ い て の 一 般 的 な 知 見 と考 察 を人 間 活 動,特 に化 石 燃 料 の 消 費 や 作 物 生 産 の 増 大 に 関 連 させ て 論 じ た。 す なわ ち大 気 中 のCO2の 増 加 はC‑O‑Fe‑Sサ イ クル と大 気 の 間 の 短 絡 に起 因 し,メ タ ン ・亜 酸 化 窒 素 の 増 大 は有 機 物 の 増 産 に起 因 して い る。 VAN VUUREN 生 態 系 各 論 にお い て はい つ くか の 代 表 的 な場(ヒ ース ラ ン ド ,水 稲 根 圏,ツ ン ド ラ とタ イ ガ,湖, 熱 帯 ダ ム湖,河 口 と沿 岸 域)お よび 地 球 規 模 のN2 Oに 関 す る 大 気 ・生 態 系 相 互 作 用 に関 す る 最 近 の 成 果 を ま とめ,い くつ か の場 に つ い て は模 式 図 を 提 示 した。 References AERTS, R. and F. BERENDSE(1989): Above-ground nutrient turnover and net primary production of an evergreen and a deciduous species in a heathland ecosystem. J. Ecology, 77: 343-356. AERTS,R., F. BERENDSE, N. M. KLERKand C. BAKKER (1989): Root production and root turnover in t wo dominant species of wet heathlands. Oecologia, 81: 374-378. ALLER,R. C. (1982): The effects of microbenthos on chemical properties of marine sediment and, overlying water, p. 53-102. In P. L. MCCALLand M. J. S. TEVESZ(eds.), Animal-Sediment Relations. Plenum Press. BERENDSE, F. (1990): Organic matter accumulation and nitrogen mineralization during secondary succession in heathland ecosystems. J. Ecology, 78: 413-427. BERKNER,V. L. and L. C. MARSHALL(1964): In P. J. BRANCAZIO and A. G. W. CAMERON(eds.), The origin and evolution of atmosphere and oceans. John Wiley & Sons, Inc. BOLIN, B., E. T. DEGENS,S. KEMPEand P. KETNER (eds.) (1979): The Global Carbon Cycle (SCOPE Report 13). John Wiley & Sons, Inc. BoUWMAN,A. F. (1990): Exchange of greenhouse gases between terrestrial ecosystems and the atmosphere, p. 61-127. In A. F. BOUMAN(ed.), Soils and the greenhouse effect. John Wiley & Sons, Inc. BUTLER,J. H., J. W. ELKINS,T. M. THOMPSONand K. B. EGAN(1989): Tropospheric and dissolved N2 Oof the west Pacific and east Indian Oceans during the El Nino southern oscillation event of 1987. J. Geophys. Res., 94: 14, 865-877. CICERONE, R. J. (1989): Analysis of sources and sinks of atmospheric nitrous oxide (N2O). J. GEOPHVS.Res., 94: 18, 265-18, 271. CICERONE, R. J. and J. D. SHETTER(1981): Sources of atmospheric methane: measurements in rice paddies and a discussion. J. Geophys. Res., 86: 7203-7209. CICERONE,R. J., J. D. SHETTERand C. C. DELWICHE (1983): Seasonal variation of methane flux from a California rice paddy. J. Geophys. Res., Gas Exchange 88: 11022-11024. CICERONE, R. J. and R. S. OREMLAND (1988): Biogeochemical aspects of atmospheric methane. Global Biogeochemical Cycles, 2: 299-327. CLINE, J. D., D. P. WISEGARVER and K. KELLYHANSEN (1987): Nitrous oxide and vertical mixing in the equatorial Pacific during the 1982-1983 El Nino. Deep-Sea Res. 34: 857-873. DE BONT, J. A. M., K. K. LEE and D. F. BOULDIN (1978): Bacterial oxidation of methane in a rice paddy. Ecol. Bull. (Stockholm), 26: 91-96. GARRELS,R. M., A. LERMANand F. T. MACKENZIE (1976): Controls of atmospheric O2 and CO2: past, present, and future. Am. Sci., 64: 306-315. HIGUCHI,Y., K. YODAand K. TENSHO (1984): Further evidence for gaseous CO2 transport in relation to root uptake of CO2in rice plant. Soil Sci. Plant Nutr., 30: 125-136. HILEMAN,B. (1989): Global Warming. C & EN Washington Mar., 13 (Special Report): 25-44. HOLZAPFEL-PSCHORN, A., R. CONRADand W. SEILER (1986): Effects of vegetation on the emission of methane from submerged paddy soil. Plant Soil, 92: 223-233. HOLZAPEL-PSCHORN, A. and W. SEILER(1986): Methane emission during a cultivation period from an Italian rice paddy. J. Geophys. Res., 91: 803 -814 . INUBUSHI, K., K. HORI, S. MATSUMOTO, M. UMEBAYASHIand H-. WADA (1989): Methane emission from the flooded paddy soil to the atmosphere through rice plant. Jpn. J. Soil Sci. Plant Nutr., 60: 318-324 (in Japanese). JENKINSON,D. S. and J. H. RAYNER(1977): The turnover of soil organic matter in some of the Rothamsted classical experiments. Soil Sci., 123: 298-305. JORGENSEN, B. B. and N. P. REVSBECH(1985): Diffusive boundary layer and the oxygen uptake of sediments and detritus, Limnol. Oceanogr., 30: 111-122. JUNGE,C. E., M. SCHIDLOWSKI, R. EICIIMANand H. PIETREK(1975): Model calculation for the terrestrial carbon cycle: Carbon isotope geochemistry and evolution of photosyntetic oxygen. J. Geophys. Res., 80: 4,542-4,552. KEELING,C. D., R. B. BACASTOW, A. E. BAINBRIDGE, C. A. EKDAHL,P. R. GUENTHER,L. S. WATERMAN and J. F. S. CHIN (1976): Atmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii. Tellus, 28: 538-551. KEELING,C. D., W. G. MOCKand P. P. TANS (1979): Recent trends in the 13C/12C ratio of atmo- in Ecosystems 279 spheric carbon dioxide. Nature, 277: 121-123. KIM, K-R. and H. CRAIG(1990): Two isotope characterizations of N2O in the Pacific Ocean and constraints on its origin in deep water. Nature, 347: 58-60. KOIKE, I. and J. SORENSEN(1988): Nitrate reduction and denitrification in marine sediments p. 251273. In T. H. BLACKBURNand J. SORENSEN (eds.), Nitrogen Cycling in Coastal Marine Environments. John Wiley. KOIKE, I. (1990): Sediment denitrification measurement using a 15-N tracer method. In N. P. REVESBECH and J. SORENSEN(eds.), Denitrification in Soil and Sediment, Plenum Press (in press). KUHN, W. R. and J. F. KASTING(1983): Effects of increased CO2 concentrations on surface temperature of the early Earth. Nature, 301: 53-55. MINAMI,K. and K. YAGI(1988): Method for measuring methane flux from rice paddies. Jpn. J. Soil Sci. Plant Nutr., 59: 458-463 (in Japanese). MIZUTANI,H. and E. WADA (1985): Carbon dioxide and the biosphere, their historical relationship as inferred from carbon isotope records. Viva Origino, 13: 25-49. MOOK,W. G., M. KOOPMANS, A. F. CARTERand C. D. KEELING(1983): Seasonal, latitudinal and secular variations in the abundances and isotope ratios of atmospheric carbon dioxide. I. Results from land studies. J. Geophys. Res., 88: 1091510933. NEWMAN,M. J. and R. T. ROOD(1977): Implications of solar evolution for the Earth's early atmosphere. Science, 198: 1035-1037. NISHIO, T., I. KOIKEand A. HATTORI (1983): Estimates of denitrification and nitrification in coastal and estuarine sediments. Appl. Environ. Microbiol., 45: 444-450. OHTAKE, C. (ed.) (1978): Nihon Kankyo Zufu (Environmental Databook of Japan, supervised by T. HANYA). Kyoritsu Publ. Co. PEARMAN,G. I. and D. J. FRASER(1988): Sources of increased methane. Nature, 332:489-490. POST, W. M., W. R. EMANUEL,P. J. ZINKEand A. J. STANGENBERGER (1982): Soil carbon pools and world life zones. Nature, 298: 156-159. RASMUSSEN,R. A. and M. A. K. KHALIL (1986): Atmospheric trace gases: Trends and distributions over the last decade. Science, 232: 16231624. REEBURGH,W. C. and S. C. WHALEN (1990): High latitude, ecosystems as CH4 sources. In Proceedings Volume: SCOPE/IGBP workshop on 280 WADA, LEE, KIMURA, KOIKE, REEHURGH, TUNDISI, YOSIINARI, YOSHIOKA and VAN VUUREN "Trace Gas Exchange in a Global P erspective". Sigtuna, Sweden, 19-23 February 1990. SEILER,W., A. HOLZAPFEL-PSCHORN, R. CONRADand D. SCHARFFE(1984): Methane emission from rice paddies. J. Atmospheric Chem., 1: 241-268. SCHIDLOWSKI, M., R. EICHMANNand C. E. JUNGE (1975): Precambrian sedimentary carbonates: carbon and oxygen isotope geochemistry and implications for the terrestrial oxygen budget . Precambrian Res., 2: 1-69. SODERLUND, R. and B. H. SVENSSON(1976): The glogal nitrogen cycle, In nitrogen, phosphorus and sulfur-global cycles, SCOPE Report 7, Ecol. Bull. (Stockholm), 22: 23-73. SUMI, T. and I. KOIKE (1990): Estimation of ammonification and ammonium assimilation in surficial coastal and estuarine sediments. Limnol. Oceanogr., 35: 170-286. TAKAHASHI,K., T. YOSHIOKA,E. WADA and M . SAKAMOTO(1990): Temporal variations in carbon isotope ratio of phytoplankton in a eutrophic lake. J. Plankton Res., 12: 799-808. TSUCHIYA, K., H. WADAand Y. TAKAI(1984): Leaching of substances from paddy soils (part 3). Degree of soil reduction as a main controlling factor. Jpn. J. Soil Sci. Plant Nutr., 55: 213-219 (in Japanese). WADA,E., N. YOSHIDA,T. YOSHIOKA, M. YOH and Y. KABAYA:In proceeding volume on D. D. ADAMS et al. (eds.), Cycling of Reduced Gases in the Hydrosphere. E. Schweizerbart'sche Verlagsbuchhandlungen. WADA, E. (1990): Oxygen cycling. cling. Kikan Kagaku Sosetsu, No. 7 233-240. WADA,E. and A. HATTORI (1991): Nitrogen in the sea: Forms, abundances and rate processes. CRC Press. WADA, H., T. YOKOYAMAand Y. TAKAI (1983): Absorption of CO2 by rice root from soil solution of the submerged soil (1). Transfer of CO 2 from rice rhizosphere to rice shoot and the air . Jpn. J. Soil Sci. Plant Nutr., 54: 217-222 (in Japanese). WAHLEN,M. and T. YOSHINARI(1985): Oxygen isotope ratios in N2O from different environments. Nature, 313: 780-782. WALKER,J. C. G. (1983): Possible limits on the composition of the archaean ocean. Nature , 302: 518-520. WEISS, R. F. (1981): The temporal and spacial distribution of tropospheric nitrous oxide . J. Geophys. Res., 86: 7185-7195. WHALEN, S. C. and W . S. REEBURGH(1988): A methane flux time-series for tundra environments. Global Biogeochem. Cycles , 2: 399-409. WHALEN,S. C. and W. S. REEBURGH(1990a): Consumption of atmospheric methane by tundra soils. Nature, 346: 160-162. W HALEN,S. C. and W. S . REEBURGH(1990b): A methane flux transect along the trans-Alaska pipeline haul road. Tellus, 42B: 237-249. YOH, M., H. TERAI and Y. SAIJO (1988a): Nitrous oxide in freshwater lakes. Arch. Hydrobiol ., 113: 273-294. YOH, M., H. TERM and Y . SAIJO (1988b): Nitrous oxide in fresh-water lakes. Jpn. J. Limnol ., 49: 43-46. YOKOYAMA, T. and H. WADA (1983): Absorption of CO2 by rice root from soil solution of the submerged soil (2). Transfer process of CO2 from rice rhizosphere to shoot . Jpn. J. Soil Sci. Plant Nutr., 54: 223-227 (in Japanese). YOSHIDA,N., A. HATTORI,T. SAINO, S. MATSUOand E. WADA (1984): 15N/14N ratio of dissolved N2 Oin the eastern tropical Pacific Ocean . Nature, 307: 442-444. YOSHIDA,N. and S. MATSUO(1983): Nitrogen isotope ratio of atmospheric N2O as a key to the glogal cycle of N2O. Geochem. J., 17: 231-239. YOSHIDA,N., H. MORIMOTO, M . HIRANO,I. KOIKE,S. MATSUO,E. WADA, T. SAINO and A. HATTORI (1989): Nitrification rates and 15Nabundances of N2O and NO3 - in the western North Pacific . Nature, 342: 895-897. YOSHINARI,T. and M. WAHLEN(1985): Oxygen isotope ration in N2O from nitrification at wastewater treatment facility. Nature, 317: 349-350. YOSHINARI,T. (1990): Emissions of N2O from vari - ous environments-The use of stable isotope composition of N2O as tracer for the studies of N2O biogeochemical cycling . In J. SORENSEN and N. P. REVSBECII(eds.). Denitrification in Soil and Sediments, Plenum Press (in press) . YOSHIOKA, T., E. WADAand Y. SAUO(1988): Isotopic characterization of Lake Kizaki and Lake Suwa. Jpn. J. Limnol., 49: 119-128 . (Authors: Eitaro WADA, Mitsubishi Kasei Institute of Life Sciences, Minamiooya , Machida, Tokyo 194, Japan, Present address: Center for Ecological Research, Kyoto University , 4-1-23, Shimo sakamoto, Shiga Prefecture 520-01, Japan; John A. LEE, School of Biological Sciences, University of Manchester, Williamson Building , Oxford Road, Manchester M 139PL , U. K., Makoto KIMURA, Gas Exchange Faculty of Agriculture, kusa-ku, Nagoya, Ocean Research Institute, 15-1, Minamidai, William 99775-1080, of Alaska Resources University State State Dapartment for Laboratories Plaze, 12201-0509, P. O. Box of Tokyo, 1- 164, Japan; of Marine Science, Fairbanks, Alaska G. TUNDISI, Center and Applied S. P., Brazil; Chi- Isao KOIKE, Tokyo Fairbanks, U. S. A.; Jose Sao Carlos, Center University Nakano-ku, Engineering, York University, S. REEBURGH, Institute University Hydric Nagoya Aichi 464- 01, Japan; Ecology, of Sao Tadashi, of and Paulo U. S. A.; Takahito New Shinshu Nagano VUUREN, Centre University, 390, Japan; for Agrobiological 太 郎,三 菱 化 成 生 命 科 学 研 究 所,〒194東 南 大 谷11;現 Wageningen, 住 所:京 The 池 勲 夫,東 台1‑15‑1;吉 3-1-1, Mat- M. I. VAN Res., P. O. Box AA Netherlands; 和 田英 京都 町 田市 都 大 学 生 態 学 研 究 セ ン タ ー,〒 屋 大 学 農 学 部,〒464‑01名 13560, Asahi Margret 14,6700 of Wadsworth Research, 509 Albany, sumoto, 520‑01,滋 YOSHINARI, New Health, of Science, of School CEP 281 in Ecosystems 賀 県 大 津 市 下 阪 本4‑1‑23;木 京 大 学 海 洋 研 究 所,〒164東 岡 崇 仁,信 村 真 人,名 古 古 屋 市 千 種 区 不 老 町;小 京 都 中野 区 南 州 大 学 理 学 部,〒390長 松 本 市 旭3‑1‑1) Empire York Received: 6 December YOSHIOKA, Faculty Accepted: 22 May 1991 1990 野 県