Impact of nitrogen compound variability of sewage treated water on NO production in riverbeds.

Nitrous oxide (NO), a strong greenhouse and ozone depleting gas, is known to be generated in the river environment. However, the impact of sewage treated water on the production mechanism has not been clarified. In this study, NO production in the upper reach of a river was evaluated by field survey and activity test.

Methane mitigation is associated with reduced abundance of methanogenic and methanotrophic communities in paddy soils continuously sub-irrigated with treated wastewater.

Herein, we examined emissions of CH and the community structures of methanogenic archaea and methanotrophic bacteria in paddy soils subjected to a novel irrigation system, namely continuous sub-irrigation with treated wastewater (TWW). This system has recently been developed by our group to effectively reuse TWW for the cultivation of protein-rich rice. The results showed that, despite not using mineral fertilisers, the wastewater reuse system produced a rice yield comparable to that of a conventional cultivation practice and reduced CH emissions from paddy fields by 80%.

Assessment of nitrous oxide production in eutrophicated rivers with inflow of treated wastewater based on investigation and statistical analysis.

Accurate estimation and control of greenhouse gas emissions have been recognized as imperative in recent years. Therefore, frequent investigations under uniform environmental conditions are required to better understand this concept. Thus, six sampling sites with characteristic concentrations of nitrogen and other water quality parameters were selected to investigate the behavior of water quality parameters throughout the year and to statistically examine the correlations among the parameters.

Methane and nitrous oxide emissions from paddy fields with no fertilizer use under continuous irrigation with treated municipal wastewater.

Treated wastewater (TWW) irrigation has been recommended as an environmentally friendly agricultural practice and has been applied in many countries for decades. The effects of wastewater irrigation on rice yield and quality, as well as on the environment, with particular focus on greenhouse gas emissions from paddy fields with municipal wastewater irrigation, have gained substantial attention. In this study, bench-scale experiments were conducted in two cultivation seasons where seedlings of Bekoaoba, a large-grain high-yield rice variety, were transplanted and irrigated with TWW without fertilization.

Estimating the population mean for a vertical profile of energy dissipation rate.

Energy dissipation rates are an important characteristic of turbulence; however, their magnitude in observational profiles can be incorrectly determined owing to their irregular appearance during vertical evolution. By analysing the data obtained from oceanic turbulence measurements, we demonstrate that the vertical sequences of energy dissipation rates exhibit a scaling property. Utilising this property, we propose a method to estimate the population mean for a profile.

Identification of skipjack tuna (Katsuwonus pelamis) pelagic hotspots applying a satellite remote sensing-driven analysis of ecological niche factors: A short-term run.

Skipjack tuna (SJT) pelagic hotspots in the western North Pacific (WNP) were modelled using fishery and satellite remotely sensed data with Ecological Niche Factor Analysis (ENFA) models. Our objectives were to model and predict habitat hotspots for SJT and assess the monthly changes in sub-surface temperatures and mixed layer depths at fishing locations. SJT presence-only monthly resolved data, sea surface temperature, chlorophyll-a, diffuse attenuation coefficient, sea surface heights and surface wind speed were used to construct ENFA models and generate habitat suitability indices using a short-term dataset from March-November 2004.

Continuous Sub-Irrigation with Treated Municipal Wastewater for Protein-Rich Rice Production with Reduced Emissions of CH and NO.

Herein, we introduce continuous sub-irrigation with treated municipal wastewater (TWW) as a novel cultivation system to promote resource recycling and cost-effective forage rice production in Japan. However, both TWW irrigation and forage rice cultivation were previously considered to intensify CH and NO emissions. In the present study, therefore, we evaluate the emissions of greenhouse gases (GHGs) and yielding capacity of forage rice between conventional cultivation and continuous sub-irrigation systems employing different water supply rates.

Contribution of dissolved NO in total NO emission from sewage treatment plant.

The characteristics of nitrous oxide, NO, from a sewage treatment plant, which conducts nitrogen removal, and the river that receives its effluent water, were investigated by intensive daily surveys in summer and winter. NO production in the sewage treatment plant was promoted in winter when nitrite accumulated in the reaction tank. The dissolved NO concentration in the effluent water was also high in winter, which caused the dissolved NO concentration to increase in the river downstream.

The comparison of greenhouse gas emissions in sewage treatment plants with different treatment processes.

Greenhouse gas emissions from different sewage treatment plants: oxidation ditch process, double-circulated anoxic-oxic process and anoxic-oxic process were evaluated based on the survey. The methane and nitrous oxide characteristics were discussed based on the gaseous and dissolved gas profiles. As a result, it was found that methane was produced in the sewer pipes and the primary sedimentation tank.

A new Approach to El Niño Prediction beyond the Spring Season.

The enormous societal importance of accurate El Niño forecasts has long been recognized. Nonetheless, our predictive capabilities were once more shown to be inadequate in 2014 when an El Nino event was widely predicted by international climate centers but failed to materialize. This result highlighted the problem of the opaque spring persistence barrier, which severely restricts longer-term, accurate forecasting beyond boreal spring.

The seasonal variation of emission of greenhouse gases from a full-scale sewage treatment plant.

The seasonal variety of greenhouse gas (GHGs) emissions and the main emission source in a sewage treatment plant were investigated. The emission coefficient to treated wastewater was 291gCO2m(-3). The main source of GHGs was CO2 from the consumption of electricity, nitrous oxide from the sludge incineration process, and methane from the water treatment process.

An observing system simulation experiment for the Western North Pacific region.

This study investigated the effectiveness of concentrated observations for ocean state estimation in a region remote from the observation site. I executed a twin observing system simulation experiment (OSSE) for the North Pacific region, using an ocean data synthesis system, to examine how the potential effectiveness is for a well-defined criterion, the representativeness of the subsurface salinity minimum corresponding to North Pacific Intermediate Water (NPIW). The results of the OSSE show that data synthesis confined to the region corresponding to the recent origin of the NPIW (35 °N-53 °N, 130 °E-170 °E) can affect the modeled extent of the NPIW in the central Pacific at 35 °N, 180°.

Improvement of ocean state estimation by assimilating mapped Argo drift data.

We investigated the impact of assimilating a mapped dataset of subsurface ocean currents into an ocean state estimation. We carried out two global ocean state estimations from 2000 to 2007 using the K7 four-dimensional variational data synthesis system, one of which included an additional map of climatological geostrophic currents estimated from the global set of Argo floats. We assessed the representativeness of the volume transport in the two exercises.

Effective design of profiling float network for oceanic heat-content monitoring.

Schemes for optimizing ocean observation programs are presently the subject of increased interest since in principle they should lead to the improved understanding of the dynamical state of the ocean that is required within the present regime of climate change. Here we use an adjoint sensitivity analysis together with a four-dimensional fluctuating oceanic current system to identify key regions for intensive monitoring by drifting profiling float. In this way we aim to maximize observational efficiency.

Simulated rapid warming of abyssal North Pacific waters.

Recent observational surveys have shown significant oceanic bottom-water warming. However, the mechanisms causing such warming remain poorly understood, and their time scales are uncertain. Here, we report computer simulations that reveal a fast teleconnection between changes in the surface air-sea heat flux off the Adélie Coast of Antarctica and the bottom-water warming in the North Pacific.