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An ecosystem model called the “EMAGIN-B.C. ver 1.0 (Ecosystem Model for Aquatic Geologic Integrated Network for Blue Carbon)”, describing the Carbon-Nitrogen-Phosphorus-Oxygen-Calcium cycle was developed to estimate/predict carbon capture and storage in estuaries. EMAGIN-B.C. analyzes (1) carbon burial, wherein carbon is captured biologically in the pelagic and benthic ecosystems and stored in deeper sediments, (2) CO 2 uptake at the ocean surface while considering the carbonate chemistry with total alkalinity and Dissolved Inorganic Carbon (DIC) production/consumption due to biochemical processes, (3) DIC capture associated with grazing at the trophic level among phytoplankton, zooplankton, and benthic fauna, (4) the effects of hypoxia on benthic fauna and bacteria by precise modeling of the biochemical oxygen production/consumption and the resultant hypoxia, and (5) the carbon transport by integration with the hydrodynamic model. EMAGIN-B.C. was applied to Tokyo Bay, a eutrophic, shallow coastal area, and reproduced the observations well. From the model outputs, it can be observed that Tokyo Bay shows functions of climate change mitigation. In the one-year carbon budget, Tokyo Bay captured 16.6% of the DIC from the atmosphere and river as organic matter by biological processes, and 3.9% of the total carbon flowing from the atmosphere and river was stored in the deeper sediment layer.

Shallow coastal ecosystems (SCEs) are generally recognized as not only significant organic carbon reservoirs but also as sources for CO2 emission to the atmosphere, thus posing a dilemma regarding their role in climate change mitigation measures. However, we argue that SCEs can act as sinks for atmospheric CO2 under a given set of biogeochemical and socioeconomic conditions. The key properties of SCEs that show net uptake of atmospheric CO2 are often characteristic of human-dominated systems, that is, high nutrient inputs from terrestrial systems, input of treated wastewater in which labile carbon has been mostly removed, and the presence of hypoxic waters. We propose a new perspective on the potential of human-dominated SCEs to contribute to climate change mitigation, both serving as carbon reservoirs and providing direct net uptake of atmospheric CO2, in light of human systems–ecosystem interactions. Namely, if we view the land and a SCE as an integrated system, with appropriate management of both wastewater treatment and SCE, we will be able to not only suppress CO2 release but also capture and store carbon.

The earlier Tokyo Bay before reclamation (tidal flat existing system) and the existing Tokyo Bay (present system) were simulated by ECOHYM, the ecological model representing benthic-pelagic ecosystem coupling, and were compared to investigate the tidal flat function on hypoxia and ecological chain from the lower to higher level trophic production. ECOHYM demonstrated that the tidal flat existing system decreased 50 % volume of hypoxia and increased 15% biomass of benthic fauna, treated as higher level living-organism in ECOHYM compared to the present system. In contrast, inhibition of nutrients load derived from rivers did not accelerate the ecological chain path from the lower to higher trophic level, although it was effective to decrease hypoxia and mortality of benthic fauna due to oxygen depletion. These results show that a bountiful ecosystem is not restored only by the inhibition of eutrophication but also by the recreation of tidal flats.

An ecosystem model was used to evaluate the effects of reclaiming seagrass beds and creating artificial shallows with seagrass beds to mitigate the effects of the reclamation. The applied model can simulate the pelagic and benthic ecosystems including seagrass beds and tidal flats. The objectives of this study were (a) to investigate the likelihood of cultivating and maintaining seagrass beds in artificial shallows (Part 1), and (b) to understand the effects of the reclamation of seagrass beds and the creation of artificial shallows on the water quality in the estuary (Part 2). In Part 1, first, the nutrient turnover rates due to both biochemical and physical processes in the natural seagrass beds where reclamation is proposed were analyzed. Biological processes rather than physical processes were the most significant driving forces of nutrient cycles in seagrass beds. Second, the effects of filter feeding benthic fauna (suspension feeders) in the seagrass beds were analyzed. The scenario with suspension feeders resulted in higher transparency of the water column (8.7% decrease in the light attenuation coefficient) and an increase in nutrient supply (24.9% increase in NH4-N in the water column) contributing to the high specific growth rate of seagrass. Third, the specific growth rate of seagrass on the proposed artificial shallows was measured. The value on the artificial shallows set at a depth of datum line minus 0.8 m (D.L. − 0.8 m) was approximately the same as that of the natural seagrass beds. In Part 2, first, water quality in the estuary was compared among the scenarios with/without natural seagrass beds and artificial shallows. Then, the defined values of the water purification capability of (a) artificial shallows with/without seagrass beds, and (b) natural seagrass beds per unit area were evaluated. The reclamation of the natural seagrass beds resulted in a decrease of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a loss in the purification rate). In contrast, the creation of artificial shallows resulted in an increase of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a gain in the purification rate). Based on an annual average, approximately twice as much phytoplankton was removed from the artificial shallows at the depth D.L. − 0.8 m, than at the depth, D.L. − 1.5 m, and the artificial shallows with seagrass beds removed pelagic DIN and DIP at a rate 120% higher than that without seagrass beds.

ECOHYM (the Ecological Connectivity Hypoxia Model) revealed the daily and annual dynamics of the vertical biochemical-physical oxygen production and consumption rate in the tidal flat quantitatively, based on the validation from two perspectives: (1) the whole estuary, composed of temporal-spatial mutual linkage of the central bay-tidal and benthic-pelagic ecosystems (holistic approach) and (2) each biochemical and physical processes (elemental approach). The benthic oxygen consumption caused by biochemical production during daytime was higher than nighttime due to oxygen production of photosynthesis of benthic algae. This photosynthesis makes the benthic system sometimes an oxygen source for the pelagic system during daytime, although the benthic system is always an oxygen sink during night time.

A new ecosystem model – the Ecological Connectivity Hypoxia Model (ECOHYM) – was developed and applied to Tokyo Bay, a hypoxic estuary in Japan. ECOHYM permits study of the dynamics and mechanisms of hypoxia from two perspectives: (1) the whole estuary, composed of temporal-spatial mutual linkage of benthic–pelagic or central bay-tidal flat ecosystems (holistic approach), and (2) each biochemical and physical process, contributing to oxygen production/consumption (elemental approach). ECOHYM evaluates the oxygen–carbon–nitrogen–phosphorus-coupled cycle driven by physical and biochemical processes. The processes mechanically describe the ecosystem network consisting of benthic–pelagic and central bay–tidal flat ecosystem coupling. The model also describes the early diagenetic processes of the benthic ecosystems by setting a micro-scale vertical spatial resolution due to the drastic vertical change of benthic biological metabolism and its high contribution to total oxygen consumption. Model variables were mainly selected based on low trophic level; namely, phytoplankton, zooplankton, detritus, dissolved organic matter, NH 4 –N, NO 3 –N, PO 4 –P, benthic algae, suspension feeders, deposit feeders (benthic faunas), dissolved oxygen (DO) and oxygen demand units (ODU, representing the stoichiometric expression of Mn 2+ , Fe 2+ and S 2− oxygen demand). Detritus was divided into fast-labile, slow-labile and refractory parts. Bacterial mineralization processes were divided into oxic, suboxic and anoxic fractions. The model was applied for a time frame of 100 years under seasonal forcing functions to achieve an annual periodical steady state. The model results revealed that the seasonal dynamics were more noticeable than the daily/tidal dynamics in the central bay area. In contrast, the daily/tidal dynamics were determinant in the tidal flat area. Calculated seasonal dynamics in the central bay and daily/tidal dynamics in the tidal flat were in good agreement with the observed data. In particular, the model succeeded in reproducing the following vertical DO profiles during the hypoxic season (summer): (1) high oxygen at the sea-surface and hypoxia at the sea-bottom in the central bay area, (2) the reduced thickness of the benthic oxic layer in the central bay area, and (3) the drastic change of DO micro-profiles between daytime and nighttime of the benthic system in the tidal flat areas. Oxygen fluxes at the sediment–water interface in the model also reproduced the in situ observed values both in the central bay and tidal flat areas.

The oxygen consumption mechanism in the benthic ecosystem of Tokyo bay was estimated by using ECOHYM, the first ecosystem model describing the ecological connectivity consisting of both benthic-pelagic and central bay-tidal flat ecosystem coupling while simultaneously describing the vertical micro-scale in the benthic ecosystem (Sohma et al, 2005a).The model revealed the annual dynamics of the vertical biochemical oxygen consumption rate and mechanism. The benthic oxygen consumption during summer was quite low due to the depletion of dissolved oxygen (DO) at the seafloor. However, under the assumption of saturated DO seawater covering the seafloor, the highest level of benthic oxygen consumption was prospective in summer due to high production and accumulation of reduced substances in the pore water.

To investigate the ecological mechanism of sea-grass beds (area 1), shallow waters/tidal flats without sea-grass near the mouth of a river (area 2), and an oxygen-depleted offshore area (area 3), we developed a numerical model, which could represent the biochemical and physical processes of the coastal marine ecosystem comprised of the above three areas. The model can represent the dynamics of coupled cycle of carbon, nitrogen, phosphorous, and oxygen, dividing organic matter into five compartments viz: fast-labile POM, slow-labile POM, refractory POM, labile DOM, and refractory DOM. In addition, this model formulated three bacterial mineralization processes: oxic mineralization, suboxic mineralization, and anoxic mineralizaition. This model was applied to the “Jinno area (Jinno ecosystem)” of Atsumi Bay, Japan, where three types of areas (areas 1, 2, and 3) are all represented. The model reproduced the dynamics of the present field condition of the three areas accurately. From the analysis of the model results, we could indicate the characteristic processes of nutrient cycling in each different areas of an ecosystem. Biological fluxes, driven by suspension feeders, epiphytes and epifauna, were the main fluxes in area 1. Biological fluxes were also the main fluxes in area 2, but were largely driven by suspension feeders. In addition, physical fluxes of re-suspension in area 2 stood out compared to the other areas. Denitrification in area 2 is much larger than in areas 1 and 3. This is because the ratio of suboxic mineralization per all mineralization in that area is higher than in other areas. We also estimated the turnover rate of biological processes and physical processes in each area of the Jinno ecosystem to quantify the characteristics of nutrient cycling in each area. The turnover rate of biological or physical processes was defined as the ratio of the total biological or physical fluxes of a compartment to the mass of a compartment. The turnover rate of areas 1 and 2 were higher than area 3. The high turnover rate in area 1 is mainly due to the biological processes, whereas biological and physical processes were both important in area 2. This result means that the important driving force of nutrient cycling in sea-grass beds are the biological processes. Understanding the characteristics of the processes that cycle matter (carbon, nitrogen, phosphorus, and oxygen) through an ecosystem becomes the first step in drafting an environmental management plan.

We developed a new numerical model to investigate the dynamics of tidal flat ecosystems and their role in water quality in terms of the carbon cycle. This model was applied to Isshiki, a natural tidal flat area, which is the largest in Mikawa Bay, Japan. This model dealt with variations of biochemical or physical interaction among dissolved oxygen and C–N–P species (comprised of carbon, nitrogen, and phosphorus elements) both on a short-time scale ( 4 –N, NO x –N, and PO 4 –P are more sensitive to daily environmental variation than to seasonal environmental variation. This means that the rotation speed of these materials in the tidal flat area is fast. Here, we defined the rotation speed as the ratio of total fluxes of substance to the mass of the substance. Phytoplankton with a high rotation speed in the tidal flat area means that the tidal flat has the potential to recover from rapidly increasing phytoplankton: red tide. The model also indicated that the peculiar feature of the tidal flat is the mineralization of organic material. The effect on a long term base, is that it prevents the accumulation of sediment, which results in controlling the increase of oxygen consumption in benthic system, which is the cause of oxygen depleted water.

The zero-field and the longitudinal field spin-relaxations of positive muon (µ + ) were measured in Cu 1- x Zn x GeO 3 ( x =0, 0.01, 0.03, and 0.07) to study the spin-Peierls system. The obtained relaxation functions were separated into two components below T SP in CuGeO 3 . We conclude that the fast relaxation is originated from a few Cu 2+ spins being not coupled with spin-singlet state, and that the slow relaxation is due to the nuclear dipolar fields. The fast relaxation function shape changes to the Gaussian at 5 K in the sample of x =0.07. The system changes from the static diluted to the densed one. We also confirmed the appearances of the spin-glass-like relaxations at 5 K in the samples of x =0.03 and 0.07.

Publisher Summary This chapter develop a simple methodology to estimate amount of long-term leakage, which can be utilized by those who do not have sufficient simulation resources to create a basis for CO2 capture and storage (CCS) accounting. The leakage coefficients for estimation are derived based on storage curve calculated by each characteristic. These are location and depth of injection. The methodology can provide the first order estimate of leakage of classified ocean storage of CO2 that would be a basis for developing accounting methodology. In particular, this is intended to contribute to accounting rules for CO2 capture storage proposed by the research project discussed in the chapter. Moreover, project planners and policy makers would utilize the methodology to examine the feasibility of some CO2 ocean storage projects. Difficulty of defining the leakage in ocean storage is due to the reservoir's open structure against atmosphere and continuous interaction between ocean and atmosphere. Under the current inventory system, “emission” is supposed to be counted. When this concept of emission is applied to the leakage in ocean storage straightforwardly, emission or leakage, which means that injected CO2 into ocean reservoir is released to the atmosphere, would not be observed because the partial pressure of CO2 in the atmosphere is higher than that of ocean constantly when viewed as a whole ocean and not local area, so that ocean consistently keeps absorbing CO2 from the atmosphere.

Publisher Summary This chapter evaluates the effectiveness of CO 2 sequestration including ocean-air CO 2 communication and the effects of injected depth/area and biochemical processes on the effectiveness of CO 2 sequestration. The chapter estimates the effectiveness of ocean sequestration and perfect sequestration by using the ecosystem model "DONGRI" that can describe the CO 2 storage from the global scale including the physical and biochemical effects. The formulation of the efficiency of the sequestration (ES) and the leakage of the sequestration (LS) are defined, which are useful for assessing not only the ocean sequestration, but other media's sequestrations. The ES and LS include the effects of interaction among ocean reservoir to other reservoirs through ocean-air communication. The motivation of these two definitions comes from considering the availability of the relative estimations among any sequestration on the same base, while including the effect of changes in oceanic CO 2 absorption due to sequestrations. The chapter estimates ES of perfect sequestration to understand the effect of ocean-air communication on all methods of sequestration and the effects of CO 2 injected depth/area dependence on ES and LS of ocean sequestration are estimated.

Publisher Summary This chapter introduces ecosystem model "DONGRI" and its availabilities for the investigation of biochemical mechanisms and their response. A new global ocean ecosystem model coupled with simplified air system, named DONGRI was introduced and the model was applied to the global ocean divided into 9 regions in horizontal and 26-29 layers in vertical and atmospheric regions. In DONGRI, the time-spatial dynamics of CO2 storage in ocean is controlled by physical transport in global ocean, the transport of CO2 across the ocean-air interface, and total CO2 production/consumption caused by biochemical processes. The chapter does comparison between model outputs and observed/experimental value. The verifications were implemented in terms of time series of atmospheric CO2, spatial dependences of oceanic TCO2, each model components and, fluxes in the North Pacific area. The model could well reproduce the observed data from the view point of each term. By using this model, the chapter presents TCO2/TALK production/consumption mechanism caused by biochemical processes and indicates the effect of ecosystem response against the global warming on CO2 storage in air and ocean quantitatively.

Polarization and temperature dependence of Raman scattering spectra of CuGeO 3 has been measured from room temperature to 5 K. The observed phonons at room temperature are well assigned by the group theoretical estimation for Pbmm (D 5 2h ). The qualitative change for all possible Raman scattering spectra has not been found from room temperature to 14 K. The energy of the five inter-chain phonons increases with decreasing temperature. Below spin-Peierls transition temperature T sp (=14 K), five peaks at 27, 107, 230, 370, and 820 cm -1 have been observed for the ( c , c ) geometry while the peaks at 370 and 820 cm -1 appear for ( b , c ).

A new coastal marine ecosystem model was developed, which was composed of pelagic and benthic ecosystems, and was applied to Mikawa Bay, Japan. This model deals with variations of biochemical and physical interactions among dissolved oxygen and C-N-P species (composition formed out of carbon, nitrogen and phosphorus elements) so that it resolves the flux dynamics of carbon, nitrogen, phosphorus and oxygen elements. The physical and biochemical mechanism figured in this model is constructed for the purpose of simulating the estuarine lower trophic ecosystem, in areas where the sea was too deep for light to reach the sea-bottom. As a result of coupling the benthic with pelagic system, the effect of process of sedimentation and nutrient diffusion back to the pelagic system could be indicated. In addition, by implementing the tidal flat ecosystem model's calculation result, the integrated model can include the effect of water purification in tidal flats where the light can reach the sea-bottom, and where seaweed, sea grass and benthic algae exist. In this study, the model indicates that oxygen-depleted water exists at the sea-bottom especially in summer mainly caused by an increase of oxygen consumption in the benthic system and a decrease of the vertical mixing water process. Furthermore, by comparing the case--with the tidal flat ecosystem model and the case without it, the effect of water purification of tidal flat estuaries was indicated. From the viewpoint of a short time scale, the tidal flat has the potential to restrict red tide (rapid increase of phytoplankton), and from the viewpoint of a long time scale, it restricts the sedimentation of detritus. Restricting the sedimentation prevents oxygen-depleted water occurring in the coastal marine system of Mikawa Bay.

Estuarine and shallow coastal systems (ESCS) are recognized as not only significant organic carbon reservoirs but also emitters of CO2 to the atmosphere through air–sea CO2 gas exchange, thus posing a dilemma on ESCS’s role in climate change mitigation measures. However, some studies have shown that coastal waters take up atmospheric CO2 (Catm), although the magnitude and determinants remain unclear. We argue that the phenomenon of net uptake of Catm by ESCS is not unusual under a given set of terrestrial inputs and geophysical conditions. We assessed the key properties of systems that show the net Catm uptake and found that they are often characteristic of human-dominated systems: (1) input of high terrestrial nutrients, (2) input of treated wastewater in which labile carbon is highly removed, and (3) presence of hypoxia. We propose that human-dominated ESCS are worthy of investigation as a contributor to climate change mitigation.