Search

Data of the atmospheric activity concentrations (in Bq/m

This study presents the results of the ERTDF S-12 project for searching an optimum reduction scenario of the short-lived climate pollutants (SLCPs) to simultaneously mitigate the global warming and environmental problems. The study utilized REAS emission inventory, Asia-Pacific Integrated Model-Enduse (AIM/Enduse), MIROC6 climate model, NICAM non-hydrostatic atmospheric model, and models for estimating environmental damages to health, agriculture, and flood risks. Results of various scenario search indicate that it is difficult to attain simultaneous reduction of global warming and environmental damages, unless a significant reduction of CO2 is combined with carefully designed SLCP reductions for CH4, SO2, black carbon (BC), NOx, CO, and VOCs. In this scenario design, it is important to take into account the impact of small BC reduction to the surface air temperature and complex atmospheric chemical interactions such as negative feedback between CH4 and NOx reduction. We identified two scenarios, i.e., B2a and B1c scenarios which combine the 2D-scenario with SLCP mitigation measures using End-of-Pipe (EoP) and new mitigation technologies, as promising to simultaneously mitigate the temperature rise by about 0.33 °C by 2050 and air pollution in most of the globe for reducing damages in health, agriculture, and flood risk. In Asia and other heavy air pollution areas, health-care measures have to be enhanced in order to suppress the mortality increase due to high temperature in hot spot areas caused by a significant cut of particulate matter. For this situation, the B1b scenario is better to reduce hot spot areas and high-temperature damage to the public health.

We have determined the hourly atmospheric concentrations of

The spatio-temporal distribution of atmospheric radioiodine immediately after the Fukushima Daiichi Nuclear Power Plant (FD1NPP) accident has not yet been clarified due to very limited observed data, compared with atmospheric radiocaesium data. Here, we first revealed that the ratios of 131I (decay-corrected to March 11, 2011) to 137Cs in radioactive plumes were divided into three groups (A, B, and C) by analysing all published data on atmospheric 131I concentrations independently measured immediately after the accident in eastern Japan. Groups A and C were found regardless of whether the measurement sites were located in eastern Fukushima or Kantou areas, while group B was observed only in the eastern Kantou area. The ratios in group A were approximately equal to 10 for the plumes on March 15, March 20, and on the morning of March 21, and those in group B were approximately 75 on March 16. Their possible sources were Unit 2 and/or Unit 3. In contrast, the ratios in group C were approximately equal to 360, much higher than those of groups A and B, and were observed from the afternoon of March 21 to March 25. These high 131I concentrations could be released after water supply to FD1NPP.

On March 11, 2011, the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident occurred and large amounts of radionuclides were discharged into the atmosphere. We have operated continuous aerosol samplings at four locations in Japan from the accident until the end of 2011. The activities of 90Sr and 137Cs in the aerosol samples were measured using low background liquid scintillation counters and high-purity germanium detectors, respectively. The atmospheric 90Sr and 137Cs concentrations decreased exponentially during 2011. The time variation of the 90Sr/137Cs ratio was obtained, and we found that the ratio rose from 1.2 × 10–3 in March to 1.3 × 10–1 in August 2011. One reason for the increase in the 90Sr/137Cs ratio could be the change in the primary emission source of activity at the FDNPP, which occurred near June 2011.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2018-01-25, 資料番号: PA1810047000

The Fukushima Dai-ichi Nuclear Power Plant accidents following the March 11, 2011 Tohoku earthquake, and subsequent tsunami released radioactive materials into the atmosphere and caused significant public health concerns, particularly thyroid cancers in children. However, the lack of measurement data for atmospheric concentrations of

To retrieve the diffusion trajectory of the

The amount of 137Cs released by the Fukushima Dai-ichi Nuclear Power Plant accident of 11 March 2011 was inversely estimated by integrating an atmospheric dispersion model, an a priori source term, and map of deposition recorded by aircraft. An a posteriori source term refined finer (hourly) variations comparing with the a priori term, and estimated 137Cs released 11 March to 2 April to be 8.12 PBq. Although time series of the a posteriori source term was generally similar to those of the a priori source term, notable modifications were found in the periods when the a posteriori source term was well-constrained by the observations. Spatial pattern of 137Cs deposition with the a posteriori source term showed better agreement with the 137Cs deposition monitored by aircraft. The a posteriori source term increased 137Cs deposition in the Naka-dori region (the central part of Fukushima Prefecture) by 32.9%, and considerably improved the underestimated a priori 137Cs deposition. Observed values of deposition measured at 16 stations and surface atmospheric concentrations collected on a filter tape of suspended particulate matter were used for validation of the a posteriori results. A great improvement was found in surface atmospheric concentration on 15 March; the a posteriori source term reduced root mean square error, normalized mean error, and normalized mean bias by 13.4, 22.3, and 92.0% for the hourly values, respectively. However, limited improvements were observed in some periods and areas due to the difficulty in simulating accurate wind fields and the lack of the observational constraints.

The Fukushima Dai-ichi Nuclear Power Plant accidents following the March 11, 2011 Tohoku earthquake, and subsequent tsunami released radioactive materials into the atmosphere and caused significant public health concerns, particularly thyroid cancers in children. However, the lack of measurement data for atmospheric concentrations of 131I has caused persistent and widespread uncertainty. This study estimated the maximum potential thyroid doses of inhaled 131I in the early post-accident phase between March 12 and 23, 2011 by using the hourly measured data of the 137Cs concentrations at 101 suspended particulate matter (SPM) monitoring sites, a new multi-model ensemble (MME) method of simulating 137Cs concentrations using two Atmospheric Transport and Deposition Models (ATDMs), the 131I/137Cs ratio obtained from measurement data analysis, and the internal exposure model. Based on the measurements, the maximum potential thyroid doses were estimated at 3.1–160 mSv at 5 sites in the Fukushima-Hamadori area for 1-year-old children assumed to remain outdoors, whereas they were less than 4.3 mSv at the other sites in the base case of the 131I/137Cs ratio. The spatial distribution of the maximum potential of early inhalation doses was estimated by using the MME and measurements. The inhalation thyroid doses in the evacuation scenarios were compared to the estimates reported by previous studies. The results of the present study were almost congruent with the outcomes of previous investigations except for thyroid doses contributed by highly contaminated plumes on March 12 and 15. The sensitivity analysis for the 131I/137Cs ratio indicated that these plumes carried the potential to significantly increase the thyroid doses of residents.

International audience; A model intercomparison of the atmospheric dispersion of cesium-137 (137Cs) emitted after the Fukushima Daiichi Nuclear Power Plant accident in Japan was conducted to understand the behavior of atmospheric 137Cs in greater detail. The same meteorological data with a fine spatiotemporal resolution and an emission inventory were applied to all models to exclude the differences among the models originating from differences in meteorological and emission data. The meteorological data were used for initial, boundary, and nudging data or offline meteorological field. Furthermore, a horizontal grid with the same resolution as that of the meteorological data was adopted for all models. This setup enabled us to focus on model variability originating from the processes included in each model, for example, physical processes. The multimodel ensemble captured 40% of the atmospheric 137Cs events observed by measurements, and the figure of merit in space for the total deposition of 137Cs exceeded 80. The lower score of the atmospheric 137Cs than that of the deposition originated from the difference in timing between observed and simulated atmospheric 137Cs. Our analyses indicated that meteorological data were most critical for reproducing the atmospheric 137Cs events. The results further revealed that differences in 137Cs concentrations among the models originated from deposition and diffusion processes when the meteorological field was simulated reasonably well. The models with small deposition fluxes produced higher scores for atmospheric 137Cs, and those with strong diffusion succeeded in capturing the high 137Cs concentrations observed; however, they also tended to overestimate the concentrations. ©2018. The Authors.

On March 11, 2011, the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident occurred and large amounts of radionuclides were discharged into the atmosphere. We have operated continuous aerosol samplings at four locations in Japan from the accident until the end of 2011. The activities of

International audience; Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in March 2011, atmospheric simulation models have improved our understanding of the atmospheric behavior of radionuclides. Model intercomparisons provide valuable and useful information for evaluating the validity and variability of individual model results. In this study, we compared results of seven atmospheric transport models used to simulate 137Cs released from the FDNPP to the atmosphere. All model results used in this analysis had been submitted for a model intercomparison project of the Science Council of Japan (2014, http//www.scj.go.jp/en/report/index.html). Here we assessed model performance by comparing model results with observed hourly atmospheric concentrations of 137Cs, with a particular focus on nine plumes over the Tohoku and Kanto regions. The intercomparison results showed that model performance in reproducing 137Cs concentrations was highly variable among different models and plumes. In general, models better reproduced plumes that passed over many observation stations. The performance among the models was consistent with the simulated wind fields and the source terms used. We also assessed model performance in relation to accumulated 137Cs deposition. Simulated areas of high 137Cs deposition were consistent with the simulated 137Cs plume pathways, though the models that best simulated atmospheric 137Cs concentrations were different from those that best simulated deposition. The ensemble mean of all models consistently reproduced atmospheric 137Cs concentrations and deposition well, suggesting that use of a multimodel ensemble results in more effective and consistent model performance. ©2018. American Geophysical Union. All Rights Reserved.

This chapter provides results of the simultaneous measurements of emission, production, and oxidation of methane (CH4) in a Japanese rice paddy field during an entire cultivation period. It focuses on seasonal changes of CH4 production and oxidation in different depths of paddy soil, and their relationship to CH4 emission, in order to understand factors controlling this process in paddy fields. A field study was carried out in an experimental paddy field of the Ryugasaki Branch of the Ibaraki Agricultural Experiment Station during the 1991 growing season. The soil of the paddy field is classified as Gley soil. The closed chamber method was used for the measurements of the CH4 emissions from paddy fields into the atmosphere. Temperature of air and paddy soil at the depths of 0, 2, 5, and 10 cm was continuously recorded during the cultivation periods by using Pt-resistance thermometers and a data logger.

An aerosol-coupled global nonhydrostatic model with a stretched-grid system has been developed. Circulations over the global and target domains are simulated with a single model, which includes fine meshes covering the target region to calculate meso-scale circulations. The stretched global model involves lower computational costs to simulate atmospheric aerosols with fine horizontal resolutions compared with a global uniform nonhydrostatic model, whereas it may require higher computational costs compared with the general regional models, because the stretched-grid system calculates inside and outside the target domain. As opposed to general regional models, the stretched-grid system requires neither a nesting technique nor lateral boundary conditions. In this study, we developed a new-type regional model for the simulation of aerosols over Japan, especially in the Kanto areas surrounding Tokyo, with a maximum horizontal resolution of approximately 10 km. This model usually reproduces temporal variations and their averages of the observed weather around Japan. This model generally reproduces monthly mean distributions of the observed sulfate and SO2 over East Asia, with high correlations (R > 0.6), but the underestimation of the simulated concentrations by 40% (sulfate) and 50% (SO2). Their underestimation of the simulated sulfate and SO2 concentrations over East Asia are strongly affected by their underestimation in China and possibly by the uncertainty of the simulated precipitation around Japan. In the Kanto area, this model succeeds in simulating the wind patterns and the diurnal transitions around the center of the Kanto area, although it is inadequate to simulate the wind patterns and the diurnal transitions at some sites located at the edge of the Kanto area and surrounded on three sides by mountains, e.g., Maebashi, mainly due to the insufficient horizontal resolution. This model also generally reproduces both diurnal and synoptic variations of the observed and/or a regional aerosol-transport model, WRF-CMAQ, simulated EC, sulfate, and SO2 concentrations in the Kanto area, especially with their high correlation (R > 0.5) at Komae/Tokyo. Although the aerosol module used in this study is relatively simplified compared to the general regional aerosol models, this study reveals that our proposed model with the stretched-grid system can be applicable for the regional aerosol simulation.

Suspended particulate matters (SPM) collected hourly at that time of Fukushima Dai-ichi Nuclear Plant accident in 2011 on a filter tape at many automated SPM monitoring stations located widely in eastern Japan was analyzed in order to determine atmospheric radiocesium concentration. Precise time series of 137Cs concentrations in wide areas of eastern Japan were revealed. Analysis of radioactivity of SPM collected on filter tapes by automated SPM monitoring stations even at 1–2 years after the accident is concluded to give very valuable information to resolve the matter of radioactive contamination by Fukushima accident.

To retrieve the diffusion trajectory of the 131I dispersed in the environment by the nuclear power plant accident in Fukushima in 2011, airborne particulate matter (APM) samples collected in the Tokyo metropolitan area were analyzed for their 129I contents by means of accelerator mass spectrometry. In evaluating blank levels of chemicals and filters used for collecting APM, we established the analytical procedure for determining the 129I activity of as low as 10−8 Bq for a small piece of filter samples (about 0.1 cm2). Coupled with 131I data determined just after the accident, activity ratios of 129I/131I were obtained with a mean value of 2.29 × 10−8 (±28% of a standard deviation). This value is systematically smaller than a mean value of soil samples by 16–24% and the inventory data by 27%, suggesting that 129I was partly lost from APM. As 129I can be a proxy of 131I for APM, it is possible to trace how 131I in the particulate phase spread in eastern Japan and, furthermore, evaluate the internal radiation exposure due to 131I by inhalation of 131I-containing airborne particulates.

This article introduces an international regional experiment, East Asian Regional Experiment 2005 (EAREX 2005), carried out in March-April 2005 in the east Asian region, as one of the first phase regional experiments under the UNEP Atmospheric Brown Cloud (ABC) project, and discusses some outstanding features of aerosol characteristics and its direct radiative forcing in the east Asian region, with some comparison with the results obtained in another ABC early phase regional experiment, ABC Maldives Monsoon Experiment (APMEX) conducted in the south Asian region. Time series of aerosol optical thickness (AOT), single scattering albedo (SSA), aerosol extinction cross section profile and CO concentration shows that air pollutants and mineral dust were transported every 5 to 7 days in the EAREX region to produce SSA values at wavelength of 700 nm from 0.86 to 0.96 and large clear-sky shortwave forcing efficiency at 500 nm from 60 W m-2 to go W m-2, though there are some unexplained inconsistencies depending on the evaluation method. The simulated whole-sky total forcing in the EAREX region is -1 to - 2 W m-2 at TOA and -2 to -10 W m-2 at surface in March 2005 which is smaller in magnitude than in the APMEX region, mainly because of large cloud fraction in this region (0.70 at Gosan versus 0.51 at Hanimadhoo in the ISCCP total cloud fraction). We suggest there may be an underestimation of the forcing due to overestimation of the simulated cloudiness and aerosol scale height. On the other hand, the possible error in the simulated surface albedo may cause an overestimation of the magnitude of the forcing over the land area. We also propose simple formulae for shortwave radiative forcing to understand the role of aerosol parameters and surface condition to determine the aerosol forcing. Such simple formulae are useful to check the consistency among the observed quantities. Copyright 2007 by the American Geophysical Union.

The amount of

We analyzed 137Cs in aerosols, rock, soil and river suspended sediment collected after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Based on the results, we discuss the post-event behavior and transportation of radiocesium in the environment from the air into ground and river systems. First, radionuclides were emitted from the FDNPP as airborne ‘hot’ particles, which contained water-soluble fractions of radiocesium. Radiocesium was still present in a water-soluble fraction after deposition on the ground. Subsequent interaction of the ‘hot’ particles with water (e.g. rainfall) dissolved and strongly fixed the radiocesium on rock and soil particles, thus changing the radiocesium into insoluble forms. The distribution of ‘hot spots’ was possibly controlled by the initial position of deposition on the ground. Consequently, ‘hot spots’ were studded on the rock surface rather than being uniformly distributed. The distribution of radiocesium in river suspended particles was not homogeneous during water transportation, reflecting the heterogeneity of radiocesium in rock and soil. Leaching experiments demonstrated that radiocesium in rock, soil and river suspended sediment was fairly insoluble, showing that the adsorption reaction is irreversible. The micro-scale heterogeneous distribution of radiocesium in aerosols, soil and suspended particles was due to the presence of ‘hot’ particles in aerosols. Dissolution of radiocesium in the ‘hot’ particles in the aerosols and subsequent irreversible adsorption onto the soil particle complex are responsible for the preservation of the heterogeneity both in soil and in river suspended particles.

To evaluate the effects of urea placement on the concentration profiles of soil gases (NO and N2O) and mineral nitrogen, we conducted an experiment in a Chinese cabbage field in Tsukuba, Japan, over one cultivation season. Soil gas and mineral nitrogen concentrations at different depths (0.05, 0.1, 0.15, 0.2, 0.3, 0.45 and 0.6 m) were measured 1–2 times per week in experimental plots fertilized by either urea incorporation (U-I; uniformly spread over the soil surface and incorporated down to approximately 0.15–0.2 m) or by urea deep band (U-DB; placed in 0.12-m-deep trenches cut at intervals of 0.6 m). Considerable NO was observed in the top 0.2 m of soil in the U-I treatment during the first 2 weeks after fertilization (WAF), whereas in soil in the U-DB treatment NO was observed only at depths of 0.1 and 0.15 m for approximately 6 WAF. In U-I, the maximum soil N2O concentration was observed 5 days after fertilization (DAF). Significantly high N2O concentration in soil of U-DB was observed 2 WAF,...

Saharjo BH, Sudo S, Yonemura S, Tsuruta H (2010) Fuel characteristics and trace gases produced through biomass burning. Biodiversitas 11: 40-45. Indonesian 1997/1998 forest fires resulted in forest destruction totally 10 million ha with cost damaged about US$ 10 billion, where more than 1 Gt CO2 has been released during the fire episode and elevating Indonesia to one of the largest polluters of carbon in the world where 22% of world’s carbon dioxide produced. It has been found that 80-90% of the fire comes from estate crops and industrial forest plantation area belongs to the companies which using fire illegally for the land preparation. Because using fire is cheap, easy and quick and also support the companies purpose in achieving yearly planted area target. Forest managementand land use practices in Sumatra and Kalimantan have evolved very rapidly over the past three decades. Poor logging practices resulted in large amounts of waste will left in the forest, greatly elevating fire hazard. Failure by the government and concessionaires to protect logged forests and close old logging roads led to and invasion of the forest by agricultural settlers whose land clearances practices increased the risk of fire. Several field experiments had been done in order to know the quality and the quantity of trace produced during biomass burning in peat grass, peat soil and alang-alang grassland located in South Sumatra, Indonesia. Result of research show that different characteristics of fuel burned will have the different level also in trace gasses produced. Peat grass with higher fuel load burned produce more trace gasses compared to alang-alang grassland and peat soil.Key words: peat soil, peat grass, alang-alang, biomass burning, trace gas.

The flux of nitrous oxide (N_2O), methane (CH_4) and carbon dioxide (CO_2) from brown lowland soils in a satsuma mandarin (Citrus unshiu Marcow, 'Silverhill', 31 years old) orchard located in Okitsu, central Japan facing the North Pacific Ocean, was measured once a week from March 2001 to February 2002 using the closed chamber method. Two categories of treatment, mulching and non-mulching, were used in the experimental field by covering the soil surface with a moisture-permeable and waterproof sheet in the latter half of fruit growing season from mid-September to mid-December in 2001. The annual N_2O emission and the amount of total nitrogen fertilized were 93mg N/m^2/year and 27.0g N/m^2/year for the non-mulching treatment and 55mg N/m^2/year and 18.9g N/m^2/year for the mulching treatment, respectively. No significant difference was found in the N_2O emission factor between mulching (0.34%) and non-mulching (0.29%) treatment. These emission factors were much lower than the average value (0.62%) for upland fields in Japan and the IPCC default value of 1.25%. On the other hand, a small amount of atmospheric methane was absorbed into the surface soils throughout the year. The annual uptake of CH_4 was 24 and 17mg CH_4/m^2/year for the non-mulching and mulching treatment, respectively, with no significant difference between the two treatments. Annual CO_2 emission with the non-mulching and mulching treatment was 1.45 and 0.89kg CO_2/m^2/year, respectively. The difference in the amount of each gas emission between the two treatments was discussed with respect to the soil temperature, water-filled pore space (WFPS), the timing and amount of nitrogen fertilized, and the effect of mulching.

Intensive field experiments were conducted from 1999 to 2001 to examine the effects of farmland improvement on methane (CH4) emission from two rice paddy fields in Niigata, Japan. Rice cultivation and field management were similar in both paddy fields; however, one field had a subsurface drainage system installed 0.6–0.8 m below the soil surface (drained paddy field) and the other had no such system (nondrained paddy field). Methane emissions from the drained paddy field during each rice-growing season were approximately 71% lower than those from the non-drained paddy field. The subsurface drainage system lowered the groundwater level and top of the gley soil layer to the drainage pipe level, enhanced soil permeability, and resulted in more oxidized soil conditions in the fallow season. The lower total and hot water extractable carbon in the plowed layer soil of the drained field versus the non-drained field strongly suggests that the organic substrate that gives rise to CH4 decomposed more quickly in the drained field. Ferrous iron concentrations in the fresh plowed layer soil, collected from before submergence up to mid-summer drainage, were also much lower in the drained field. This indicated that ferrous iron produced during the flooding seasons was quickly oxidized to ferric iron in the fallow season, which then acted as an electron accepter and inhibited CH4 production in the subsequent rice-growing season. In contrast, the continuous reductive conditions in the non-drained field (even in the fallow season) prevented most of the ferrous iron from being oxidized. Therefore, installing a subsurface drainage system greatly reduced CH4 emissions by improving aerobic conditions and reducing CH4 production potential. Methane emissions with a large inter-annual variation in the rice-growing season from the non-drained field were positively correlated with soil moisture in the plowed layer before submergence, which, in turn, greatly affected CH4 emission in the following rice-growing season.

To assess their impacts on net global warming, total greenhouse gas emissions (mainly CO2, N2O and CH4) from agricultural production in arable land cropping systems in the Tokachi region of Hokkaido, Japan, were estimated using life cycle inventory (LCI) analysis. The LCI data included CO2 emissions from on-farm and off-farm fossil fuel consumption, soil CO2 emissions induced by the decomposition of soil organic matter, direct and indirect N2O emissions from arable lands and CH4 uptake by soils, which were then aggregated in CO2-equivalents. Under plow-based conventional tillage (CT) cropping systems for winter wheat, sugar beet, adzuki bean, potato and cabbage, on-farm CO2 emissions from fuel-consuming operations such as tractor-based field operations, truck transportation and mechanical grain drying ranged from 0.424 Mg CO2 ha−1 year−1 for adzuki bean to 0.826 Mg CO2 ha−1 year−1 for winter wheat. Off-farm CO2 emissions resulting from the use of agricultural materials such as chemical fertilizer...

Methane production potential (MPP) of rice soil, defined here as the mean value of methane production rate (MP-R) of rice soil over a given period in which the substrate for methanogenesis is presumably depleted, significantly affects CH4 emission to the atmosphere. To expand our understanding of how MPP was affected in soils grown with different rice cultivars (Yanxuan, 72031 and 9516) and its consequence on CH4 emission, the changing pattern of MP-R was elucidated in the present study. On an entire rice growing scale, the MPP of planted soil was significantly higher than that of unplanted soil, and the MPP of 72031 rice soil was 9.42 µg CH4 kg (d.w.s) −1 h−1, significantly lower than Yanxuan (18.2 µg CH4 kg (d.w.s) −1 h−1) and 9516 rice soils (17.7 µg CH4 kg (d.w.s) −1 h−1). Yanxuan and 9516 soils had a similar MP-R changing pattern, which was distinct from 72031 soil. On a temporal scale of the representative rice growing stages (i.e. early tillering, late tillering, panicle initiation, ripeni...

Nitrous oxide (N2O) and nitric oxide (NO) fluxes resulting from long-term tomato cultivation in a glasshouse were continuously determined using the flow-through chamber method over the course of three cultivation periods. Gas concentrations were measured using an nondispersive infrared (gas filter correlation/infra-red) analyzer and a chemiluminescence-based analyzer, respectively. Following a basal application of fertilizer, daily N2O and NO emission rates increased, with peaks lasting from 40 to 140 days. Short-term fluctuations in daily N2O and NO emissions were affected by differences in nitrogen application, soil water, and soil temperature. Diurnal changes in N2O and NO fluxes during the period of peak emissions depended primarily on soil temperature. Following the application of a top dressing (N as urea or calcium nitrate) in the irrigation water, the N2O and NO fluxes increased immediately, with a very short period of peak emissions (1–5 h) after urea application. The duration of the peak period in daily accumulated N2O and NO emissions following application of the top dressing ranged from 3 to 10 days.

We conducted a field experiment in an Andosol near Tsukuba (Japan) to study the effects of the type of nitrogen fertilizer on nitrous oxide (N2O) emissions and on nitrogen uptake by Chinese cabbage (Brassica campestris L.). We used four treatments: fertilizer containing no nitrogen (CONT), broadcast application of urea (BR-U), band application of urea (B-U), and band application of controlled-release urea (B-CU). The application rate was 250 kg N ha−1, a conventional rate in the region. We measured N2O flux two or three times a week during the 82-day growth period, then divided the cumulative emissions into three stages: early (28 days), middle (27 days), and late (27 days). The temporal variation in N2O emissions differed among the treatments. Broadcast urea application produced 70% of N2O emissions during the early stage. N2O emissions increased with increasing cabbage growth in the CONT treatment, indicating that plant growth accompanied by increasing root biomass could stimulate N2O emissions from unfertilized soil. There were no differences in the patterns of temporal variation in N2O flux between the two band applications (B-U and B-CU); N2O emissions in the early and middle stages were 46 and 42%, respectively, for B-U, vs. 41 and 40% for B-CU. However, the overall N2O emission was reduced by 40.5% in the B-CU treatment compared with the B-U treatment. N2O emissions from the soils within fertilized bands were dramatically higher than those between the fertilized bands, and this trend continued until harvesting.

A system for simultaneous and continuous measurement of fluxes of three major greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), from croplands was developed based on the closed chamber method. Controlled by a computer, top-lids of the chambers placed in the field closed periodically, remained closed for about 30 min, and then opened again. During the closure of the chambers, the air in the chambers was circulated by air pumps, and part of the circulated air was injected to gas analyzers. CO2 concentration was monitored with an infra-red gas analyzer, and its increasing/decreasing rate during the 1-3-min period after the chamber closure was used for the flux calculation. Concentrations of CH4 and N2O were measured with two gas chromatographs 4 times at intervals of 8.5 min. The system was tested in lysimeter fields with Gray lowland soil under various conditions, including paddy rice cultivation, upland crop cultivation and also fallow condition. Both CH4 and N2O concentrations...

Wetland plants not only stimulate CH 4 emissions from wetlands to the atmosphere by providing the gas conduit and releasing organic compounds through root exudation and debris to increase CH 4 production, but also reduce CH 4 emissions by delivering O 2 into the underground to accentuate CH 4 oxidation in the rhizosphere. The capacity of the plants Carex lasiocarpa , Carex meyeriana and Deyeuxia angustifolia to transport CH 4 from freshwater marshes in Sanjiang plain, China to the atmosphere was measured. Their integrated effects on dissolved porewater CH 4 concentration and CH 4 emission were studied by clipping plants just above the water surface. The amount and fraction of CH 4 emissions via intact plants C. lasiocarpa , C. meyeriana and D. angustifolia was 16.0, 20.8 and 8.0 μg CH 4 stem −1 h −1 , and 73–82%, 75–86% and 28–31%, respectively, indicating that when CH 4 is released by the diffusive rather than pressurized transport through the aerenchyma system, cyperaceous plants have a significantly higher gas transport capacity than gramineous plants. After plants were clipped 3 cm above the water surface, CH 4 emissions and CH 4 concentrations in the C. lasiocarpa marsh with a standing water depth of ∼20 cm increased significantly; only slight increases were measured in the C. meyeriana marsh with a standing water layer of ∼15 cm. The redox potentials ( E h ) in the vertical profiles of both marshes were further lowered after plants were clipped. These results suggest that apart from being a conduit for gas transport, C. lasiocarpa made a greater contribution to CH 4 oxidation than CH 4 production, whereas C. meyeriana made nearly the same contribution to CH 4 oxidation as to CH 4 production. In contrast, a decrease in dissolved porewater CH 4 concentration and a very limited increase in CH 4 emission in the D. angustifolia marsh with a standing water depth of ∼5 cm indicated that D. angustifolia might make a greater contribution to CH 4 production than to CH 4 oxidation. Thereafter, as the standing water depth and the capacity of plants to transport CH 4 from wetlands increased, plant integrated effect of stimulating CH 4 production by releasing root exudates and debris minus accentuating CH 4 oxidation by excreting O 2 from roots not only decreased but also varied from increasing CH 4 concentration for D. angustifolia to reducing CH 4 concentration for C. lasiocarpa . The higher CH 4 emission in the C. lasiocarpa marsh than in the D. angustifolia marsh was due to the high CH 4 transport capacity of C. lasiocarpa rather than the stimulating effect of C. lasiocarpa on CH 4 production. This finding suggests that when models are used for estimation of CH 4 emissions from natural wetlands, difference in plant species effect on CH 4 production and oxidation should be involved in.

Values of δ13C and δ15N of soil organic matter (SOM) under different land cover in Pasir Mayang, Jambi Province, Sumatra Island, Indonesia were examined to apply them as indicators of SOM dynamics and related CO2 production. The δ13C and δ15N values of SOM increased with depth in the 0–30 cm layer in the preserved forest, reflecting 13C and 15N richment in SOM through mineralization and immobilization. The degree of vertical enrichment, difference between 0–5 cm and 10–15 cm SOM, was more pronounced in δ15N than in 13C at all sites in Pasir Mayang. The δ13C -SOM profiles fluctuated through clear-cutting the forest and subsequent burning, which was due to input of biomass with higher C/N molar ratio and lower 13C value than the original SOM. However, the δ15N-SOM profiles before and after such a drastic event did not change appreciably. The δ15N-SOM became higher as the C/N ratio decreased and as soil sugar content decreased. These observations suggest that δ15N-SOM is a variable that changes with the amount of easily decomposable organic matter (EDOM) in soil. Soil incubation experiments demonstrated a correlation between CO2 production rate and degree of vertical 15N-enrichment in SOM, which was applied to field data to estimate CO2 production through SOM decomposition. A similar analysis was performed with the soils collected at 27 locations in other districts in Jambi Province than Pasir Mayang. In five locations covered by oil palm plantation, CO2 production through SOM decomposition controlled 70 of variation in CO2 emission among the locations. In the remaining 22 locations, however, the CO2 emission was neither related to CO2 production from SOM nor to ground litter amount. This observation indicated that mechanisms other than dead organic matter decomposition such as root respiration were dominant sources for CO2 emission in these sites.

We measured fluxes of three greenhouse gases (N2O, CO2O and CH4) from soils of six different land-use types at 27 temporary field sites in Jambi Province, Sumatra, Indonesia. Study sites included natural and logged-over forests; rubber plantation; oil palm plantation; cinnamon plantation; and grassland field. The ranges of N2O, CO2 and CH4 fluxes were 0.13–55.8 μgN m-2h-1; 1.38–5.16 g C m-2d-1; −1.27–1.18 mg C m-2d-1, respectively. The averages of N2O, CO2 and CH4 fluxes at 27 sites were 9.4 μgN m-2h-1,3.65 g C m-2d-1, −0.45 mg C m-2d-1, respectively. The values of CO2 and CH4 fluxes were comparable with those in the reports regarding other humid tropical forests, while the N2O flux was relatively lower than those of previous reports. The N2O fluxes in each soil type were correlated with the nitrification rates of soils of 0–5 cm depth. In Andisols, the ratio of the N2O emission rate to the nitrification rate was possibly smaller than that of the other soil types. There was no clear relationship between N2O flux and the soil water condition, such as water-filled pore space. Seventeen percent of CH4 fluxes were positive; according to these positive fluxes, we did not find a good correlation between CH4 uptake rate and soil properties. Although we performed a chronosequence analysis to produce some hypotheses about the effect of land-use change by a limited amount of sampling at one point in time, further tests are required for the future.

The most probable number (MPN) method and dicyandiamide (DCD), an autotroph-specific inhibitor, were used to identify microbial processes that produced N2O in acid soils. Nitrous oxide production was investigated in six sites in four different land-use patterns at Pasirmayang in Jambi province, in Sumatra, Indonesia, using soils collected in October 1999, March 2000 and June 2000. The six sites were primary forests (P1 and P2), loggedover forests (L2), a young rubber plantation established after forest had been logged and burned in March 1998 (L1), a plantation of Gmelina arborea established after logging and burning of forest in August 1996 (O), and a rubber plantation of a small landholder established in 1993 (R). Very small numbers of autotrophic ammonia oxidizers and autotrophic nitrite oxidizers were detected. Heterotrophic nitrifiers were detected at all sites, with the highest MPNs at L1 and L2. In incubation experiments, the emission of N2O from soils increased at all six sites after adding citrate, a substrate for heterotrophic nitrifiers. No correlation appeared between denitrification activity and N2O flux. We conclude that heterotrophic nitrifiers are the main microbial contributors to N2O emission from acid soils in Pasirmayang, Jambi.

Methane (CH4) emissions from peat soils in tropical and temperate wetlands were compared. Annual CH4 emission rates in Ozegahara, the largest wetland on Honshu main island, Japan, were higher than in drained forest wetland areas examined in Indonesia. Methane emissions from the lowland paddy fields examined in Indonesia were higher than those of peaty paddy fields in Japan. There was generally a positive correlation (r2 = 0.09; P < 0.1) between CH4 emissions and CH4 production activities in wetland soils. In Ozegahara, there was a positive relationship (r2 = 0.80; P < 0.01) between CH4 production activities and soil pH, but there was no such relationship in Indonesia. The range of soil pH in Ozegahara was 5–7, while pH values in the Indonesian sites were lower than 5. There was a positive response of CH4 emission with respect to groundwater level in all of these areas. In Indonesia, land-use change from swamp and drained forest to cassava or coconut field lowered groundwater levels and decreased CH4 emission, while change to lowland paddy raised the groundwater level and increased CH4 emission. Addition of acetate generally inhibited CH4 production during the early period (until 2 weeks) of incubation, then enhanced it afterward in both Ozegahara and Indonesian wetland soils. Addition of hydrogen mostly enhanced CH4 production. From the results of this study, CH4 fluxes from peat soil to the atmosphere were positively correlated with CH4 production activities, and CH4 production activity in peat soil was regulated by soil pH, while land-use change from wetland to upland crop lowered groundwater level and thus reduced CH4 production and enhanced CH4 oxidation.

Monthly measurements of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes in peat soils were carried out and compared with groundwater level over a year at four sites (drained forest, upland cassava,upland and lowland paddy fields) located in Jambi province, Indonesia. Fluxes from swamp forest soils were also measured once per year as the native state of this investigated area. Land-use change from drained forest to lowland paddy field significantly decreased the CO2 (from 266 to 30 mg C m−2 h−1) and N2O fluxes (from 25.4 to 3.8 μg N m−2 h−1), but increased the CH4 flux (from 0.1 to 4.2 mg C m−2 h−1) in the soils. Change from drained forest to cassava field significantly increased N2O flux (from 25.4 to 62.2 μg N m−2 h−1), but had no significant influence on CO2 (from 266 to 200 mg C m−2 h−1) and CH4 fluxes (from 0.1 to 0.3 mg C m−2 h−1) in the soils. Averaged CO2 fluxes in the swamp forests (94 mg C m−2 h−1) were estimated to be one-third of that in the drained forest. Groundwater levels of drained forest and upland crop fields had been lowered by drainage ditches while swamp forest and lowland paddy field were flooded, although groundwater levels were also affected by precipitation. Groundwater levels were negatively related to CO2 flux but positively related to CH4 flux at all investigation sites. The peak of the N2O flux was observed at –20 cm of groundwater level. Lowering the groundwater level by 10 cm from the soil surface resulted in a 50 increase in CO2 emission (from 109.1 to 162.4 mg C m−2 h−1) and a 25% decrease in CH4 emission (from 0.440 to 0.325 mg C m−2 h−1) in this study. These results suggest that lowering of groundwater level by the drainage ditches in the peat lands contributes to global warming and devastation of fields. Swamp forest was probably the best land-use management in peat lands to suppress the carbon loss and greenhouse gas emission. Lowland paddy field was a better agricultural system in the peat lands in terms of C sequestration and greenhouse gas emission. Carbon loss from lowland paddy field was one-eighth of that of the other upland crop systems, although the Global Warming Potential was almost the same level as that of the other upland crop systems because of CH4 emission through rice plants.

Greenhouse gas emissions were measured from tropical peatlands of Kalimantan, Indonesia. The effect of hydrological zone and land-use on the emission of N2O, CH4 and CO2 were examined. Temporal and annual N2O, CH4 and CO2 were then measured. The results showed that the emissions of these gases were strongly affected by land-use and hydrological zone. The emissions exhibited seasonal changes. Annual emission of N2O was the highest (nearly 1.4 g N m−2y−1) from site A-1 (secondary forest), while there was no signi.cant difference in annual N2O emission from site A-2 (paddy field) and site A-3 (rice-soybean rotation field). Multiplying the areas of forest and non-forest in Kalimantan with the emission of N2O from corresponding land-uses, the annual N2O emissions from peat forest and peat non-forest of Kalimantan were estimated as 0.046 and 0.004 Tg N y−1, respectively. The emissions of CH4 from paddy field and non-paddy field were estimated similarly as 0.14 and 0.21 Tg C y−1, respectively. Total annual CO2 emission was estimated to be 182 Tg C y−1. Peatlands of Kalimantan, Indonesia, contributed less than 0.3 of the total global N2O, CO2 or CH4 emission, indicating that the gaseous losses of soil N and C from the study area to the atmosphere were small.

To understand the underlying factors affecting the seasonal variation of the methane concentration in a cool temperate freshwater marsh vegetated with Carex lasiocarpa in the Sanjiang Plain of northeast China, we measured methane emission from, and the concentrations of methane, dissolved organic carbon (DOC) and acetate in, water samples taken from the standing water surface to the top of the gley soil layer in the C. laisocarpa marsh, before and after plants were covered with a black cloth at the three growing stages of June, July and August 2002. The methane oxidation rate was also measured in situ by applying acetylene, a methane oxidation inhibitor, to whole plants, and the methane production rate in water sampled in June and July was measured via the anaerobic incubation in the laboratory. The methane production rate in water samples was significantly correlated with acetate concentration rather than DOC concentration, whereas the mean acetate concentration in water samples was higher in June than in July and August. Hence, the low methane concentration in June did not result from a lack of acetate for methane production. The mean methane and DOC concentrations in water samples were enhanced by 22.3 and 31.1% in June, 2.1 and 5.0% in July, and 3.4 and 15.2% in August, respectively, after plants were covered with a black cloth. The methane oxidation rate and redox potential in the freshwater marsh decreased from June to July or August. These results suggest that there was more oxygen in the rhizome and rhizosphere in June than in July and August, which not only accentuated methane oxidation but also reduced methane production. Therefore, the high methane concentration in water in July and August could be ascribed to both an increase in temperature and a decrease in redox potential or oxygen concentration in the rhizosphere.

Nitrogen regulates several ecological and biogeochemical processes and excess reactive nitrogen in the environment can lead to pollution problems, including the deterioration of air quality, disruption of forest processes, acidification of lakes and streams, and degradation of coastal waters. Much of the excess nitrogen inputs are related to food and energy production. An important step to understanding the sources of nitrogen and ultimately defining solutions to excess nitrogen is to describe the geographic distribution of agricultural nitrogen contributions from different regions. In this study, soil surface nitrogen loads were quantified for different states of India for the period 2000–2001. Nearly 35.4 Tg of nitrogen has been estimated as inputs from different sources, with output nitrogen from harvested crops of about 21.20 Tg. The soil surface nitrogen balance, estimated as inputs minus outputs, is found to be about 14.4 Tg surplus from the agricultural land of India. Livestock manure constituted a major percentage of total inputs (44.06%), followed by inorganic fertilizer (32.48%), atmospheric deposition (11.86%) and nitrogen fixation (11.58%). Nitrogen balance varied from deficit to surplus for different states. The highest nitrogen surplus was found in Uttar Pradesh (2.50 Tg) followed by Madhya Pradesh (1.83 Tg), Andhra Pradesh (1.79 Tg), etc. A negative nitrogen balance was found in Orissa (−0.01 Tg), Andaman Nicobar Islands (−0.32 Tg) and for some of the northeastern states. Major fertilizer consumption states were found to be Tamilnadu (204 kg/ha), Haryana (132 kg/ha), Punjab (148 kg/ha), followed by others. Similarly, nitrogen inputs from total livestock excretions were found to be high for Kerala (616 kg/ha), Jammu and Kashmir (389 kg/ha), Tamil Nadu (338 kg/ha), etc. The average nitrogen surplus of about 54 kg/ha observed for the agricultural land of the entire country of India is comparatively higher than the average surplus of about 31 kg/ha reported for European countries. These results, obtained from nutrient mass balance calculations, will be useful to formulate nutrient management plans relating to fertilizer usage, livestock management and for adopting some best management strategies at a state level in India.

To elucidate effect of the CH4 transport capacity of plants on CH4 production and CH4 emission, we measured CH4 emission and the CH4 transport capacity of plants as well as CH4 and dissolved organic carbon (DOC) concentrations in porewater and redox potential in the freshwater marsh vegetated with Carex lasiocarpa, Carex meyeriana and Deyeuxia angustifolia. Although only 31% of CH4 emitted was released via Deyeuxia angustifolia into the atmosphere compared to 72–86% via Carex plants and the CH4 transport capacity of per stem of Deyeuxia angustifolia was only 8.0 μg CH4 stem−1 h−1 being equal to half for Carex plants, the flux of CH4 emission from the Deyeuxia angustifolia marsh was just lower by 17–28% than those from the Carex marshes as the standing water depth decreased significantly from 15–20 to 5 cm, indicating that despite the poor CH4 transport capability of Deyeuxia angustifolia partly reduced CH4 emission via plants, however CH4 emission was not greatly reduced as expected. This is because although the poor gas transport capability of Deyeuxia angustifolia lowered CH4 emission to some extent, however it also decreased the input of O2 into the rhizosphere via plants; the latter not only reduced CH4 oxidation in the rhizosphere and/or rhizome but also lowered redox potential in the vertical profile resulting in an increase in CH4 production potential and CH4 concentration especially at 5 cm depth, which in turn facilitated CH4 emission through diffusion in the Deyeuxia angustifolia marsh. This study suggests that the sharp decrease in the CH4 transport capacity of plants did not necessary result in an expected lowering of CH4 emission in the freshwater marsh.

To evaluate the effect of cultivation, nitrogen fertilizer, and set aside on CH4 uptake after drained marshland was converted into agricultural fields, CH4 fluxes and CH4 concentrations in soil gas were in situ measured in a drained marsh soil, a set-aside cultivated soil, and cultivated soils in Sanjiang Plain of Northeast China in August 2001. Over the measuring period, the highest CH4 uptake rate was 120.7±6.2 μg CH4 m−2 h−1 in the drained marsh soil and the lowest was 29.5±4.9 μg CH4 m−2 h−1 in the set-aside cultivated soil, showing that there was no significant recovery of CH4 uptake ability 5 years after cultivation activity was stopped. CH4 uptake rates were significantly less in the cultivated soils than in the drained marsh soil by 30.1–74.6%, which resulted mainly from cultivation and partly from nitrogen addition. A significantly negative correlation between CH4 flux and bulk density in the cultivated soils tilled by machine suggests that cultivation reduced CH4 uptake through compaction, because of the enhanced diffusion resistance for CH4 and O2. Nitrogen fertilization slowly reduced but persistently affected CH4 uptake even after long-term application of nitrogen.