In the radioactive waste management, metal chloride wastes from a pyrochemical process is one of problematic wastes not directly applicable to a conventional solidification process. Different from a ...use of minerals or a specific phosphate glass for immobilizing radioactive waste salts, our research group applied an inorganic composite, SAP (SiO2−Al2O3−P2O5), to stabilize them by dechlorination. From this method, a unique wasteform composing of phosphate and silicate could be fabricated. This study described the characteristic of the wasteform on the morphology, chemical durability, and some physical properties. The wasteform has a unique “domain-matrix” structure which would be attributed to the incompatibility between silicate and phosphate glass. At higher amounts of chemical binder, “P-rich phase encapsulated by Si-rich phase” was a dominant morphology, but it was changed to be Si-rich phase encapsulated by P-rich phase at a lower amount of binder. The domain and subdomain size in the wasteform was about 0.5−2 μm and hundreds of nm, respectively. The chemical durability of wasteform was confirmed by various leaching test methods (PCT-A, ISO dynamic leaching test, and MCC-1). From the leaching tests, it was found that the P-rich phase had ten times lower leach-resistance than the Si-rich phase. The leach rates of Cs and Sr in the wasteform were about 10−3g/m2· day, and the leached fractions of them were about 0.04% and 0.06% at 357 days, respectively. Using this method, we could stabilize and solidify the waste salt to form a monolithic wasteform with good leach-resistance. Also, the decrease of waste volume by the dechlorination approach would be beneficial in the final disposal cost, compared with the present immobilization methods for waste salt.
This study aims to assess the impact of climate change on the distribution of Styrax sumatrana in North Sumatra by applying the maximum entropy (MaxEnt) model with biophysical factors (elevation, ...slope, aspect, and soil), climatic factors (19 bioclimate data sets for 2050 and 2070), and anthropogenic factors (land use land cover (LULC) changes in 2050 and 2070). The future climate data retrieved and used are the output of four climate models from Coupled Model Intercomparison Project Phase 5 (CMIP5), namely, the CCSM4, CNRM-CM5, MIROC5, and MRI-CGCM3 models, under the Representative Concentration Pathways (RCPs) 4.5 and 8.5 scenarios. The MaxEnt modelling results showed the importance of the mean temperature of the coldest quarter and the LULC variables. Styrax sumatrana rely on environmental conditions with air temperatures ranging from 13 to 19 °C. The potentially suitable land types for Styrax sumatrana are shrubs, gardens, and forests. The future predictions show that the suitable habitat for Styrax sumatrana is predicted to decrease to 3.87% in 2050 and to 3.54% in 2070 under the RCP4.5 scenario. Under the RCP8.5 scenario, the suitable area is predicted to decrease to 3.04% in 2050 and to 1.36% in 2070, respectively. The degradation of the suitable area is mainly due to increasing temperature and deforestation in future predictions. The modelling results illustrate that the suitable habitats of Styrax sumatrana are likely to be reduced under future climate change scenarios or lost in 2070 under the RCP8.5 scenario. The potential future extinction of this species should alert authorities to formulate conservation strategies. Results also demonstrated key variables that should be used for formulating ex situ conservation strategies.
This study aimed to investigate the willingness of residents of ger (traditional nomadic house) areas to pay for improvements in the water supply and wastewater treatment system in terms of capital ...costs and operation and management (O&M) costs by contingent valuation (CV) method and payment card format. The problems in the ger area are a lack of a drainage system, the use of unimproved sanitation technology, and an unsafe water supply, in addition to the direct discharging of wastewater into pit latrines, soak pits, yards, and streets. The contribution of this study is the application of this method in a previously unstudied area to enhance the participation of ger communities that are absent in the development plan of Ulaanbaatar city. A field survey was conducted in one of the ger areas, the Damba planning unit, and 298 samples were collected from residents. Data were analyzed and compared using ordinary least squares (OLS) and Tobit regression models. Model results showed that the average total willingness to pay for the water supply and wastewater treatment facility installation was 1000 thousand Mongolian tugrik (MNT), and the average total willingness to pay for the operation and management costs was a maximum of 3000 MNT per month. The important factors affecting the residents’ willingness to pay (WTP) for installation were the housing type, current monthly payment for water supply, income level, and education, in order of significance. People living in their own detached house and educated greater than high school were more willing to pay for the installation of water supply and wastewater treatment facilities. Those who were paying higher for their monthly water supply were more willing to pay for the installation cost. With respect to the WTP for O&M cost, the WTP was associated with the family size, income level, housing, time for water access, and education, in order of significance. Families a larger number of members were more willing to pay, and low-income people were less willing to pay for O&M. Education showed a positive influence on the WTP for O&M. Water access time also affected the WTP of those who could not access water within 30 min, as they indicated low WTP values.
This study aims to investigate the impacts of land use changes brought by the Hanoi Master Plan 2030 (HMP) to the urban heat island (UHI), using the Weather Research and Forecasting (WRF). A scenario ...analysis was carried out to assess the effectiveness of urban greening for mitigating UHI. The urban climate under the influence of global warming was also investigated by downscaling the results of global climate simulation (MIROC5 RCP4.5) in the scenario analysis for 2030s. The results show that the land use change does not significantly increase the peak average air temperature (Tavg) in urban areas: the peak Tavg remains at almost in the same level of 37°C. Instead, it increases the number of hotspots and raises the nocturnal Tavg particularly in new urban areas by up to 1°C. Further, if the green coverage ratio in new urban areas is increased to 30% and the mixed forest is adopted as vegetation type in the green spaces, Tavg is lower by up to 0.5°C and the hotspots are reduced by up to 28%. Meanwhile, it was found that the urban air temperature is predicted to increase by up to 1.8°C due to the global warming in 2030s.
This increment has surpassed the cooling effect of UHI mitigation through urban greening.
Kim, S. and Lee, H.S., 2018. Combined approach of empirical mode decomposition and artificial neural network for sea-level record analysis. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), ...Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1091–1095. Coconut Creek (Florida), ISSN 0749-0208. In this study, we illustrate artificial signal tests analysis implying sea-level records analysis (Visser, Dangendorf and Petersen, 2015) with improved empirical model decomposition (EMD) and artificial neural network (ANN) for predicting the non-linear process of sea-level in terms of predicting a non-linear intrinsic mode for missed data and a non-linear trend. The EMD is intuitive, direct, and adaptive method for decomposing a signal into intrinsic modes, and does not require any predetermined parametric functions for analyzing a non-linear and non-stationary data. The ANN is one of machine learning methods to estimate stationary or non-stationary patterns/values. In our analyses, an artificial signal and sea-levels are decomposed into intrinsic modes, and then mainly low frequency modes are tested with ANN for predicting missing parts and for estimating future variabilities. Our results show that the combination of improved EMD and ANN is highly capable of predicting non-linear processes of sea-levels and can be applicable not only for predicting a missing data but also for estimating long-term natural variabilities and a trend.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The fast-growing population in Vientiane, the capital of Laos, has resulted in increasing domestic wastewater generation, which directly impacts the urban water environment due to the lack of a ...suitable wastewater treatment system. This study aims to assess six wastewater treatment alternatives based on two technologies—trickling filter and activated sludge—used for on-site, decentralized, and centralized wastewater treatment systems to support decision-making for selecting the most suitable and practical alternative for wastewater treatment in Vientiane. To determine the most appropriate treatment system, the wastewater treatment process simulation with BioWin and the technique for order preference by similarity to ideal solution (TOPSIS) method are applied to assess the removal efficiencies for biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solids (TSS), as well as to rank the six wastewater treatment technologies based on the following four environmental criteria: (1) land requirement, (2) electricity use, (3) sludge production, and (4) CO2 emissions. The BioWin results illustrate that the capacity of each alternative is similar in terms of domestic wastewater treatment efficiency, while differing in terms of environmental impacts. In addition, the alternative ranking shows that a centralized wastewater treatment system with a trickling-filter process is more suitable than on-site and decentralized wastewater treatment systems based on their environmental impacts. This finding provides evidence for decision-makers to select a suitable alternative for wastewater treatment in order to promote access to safe sanitation and sustainable urban wastewater management in Vientiane, Laos.
Extreme precipitation trends and events are fundamental for the definition of the region’s climate and allow the subsequent analysis of the risk for the territory and the possible countermeasures. ...This study takes into account the Marche Region (Central Italy) with 128 rain gauges from 1921 to 2017. Initially, in order to obtain a rainfall overview, the dominant trend of the period 1921–2017 was evaluated. Initially, in order to obtain a rainfall overview, the dominant trend of the period 1921–2017 was evaluated. In addition, to obtain a comparable analysis, the average precipitations grouped in climatological standard normals were analyzed. Finally, the main purpose of the research was achieved by analyzing extreme events in the middle Adriatic side. In addition, forecasts of extreme precipitation events, with a return period of 100 years, were made using the theory of “generalized extreme value” (GEV). The innovation of this research is represented by the use of geostatistics to spatialize the variables investigated, through a clear and immediate graphic representation performed through GIS software. This study is a necessary starting point for the study of climate dynamics in the region, and it is also a useful tool for land use planning.
As computational techniques advance, the scope of digital twins (DTs) is expanding to encompass entire cities, oceans, or even the Earth. Digital twins of oceans can provide highly comprehensive ...insights and predictions, thus enabling better-informed decision-making regarding ocean-related activities and management. Here, a numerical model of the Seto Inland Sea (SIS), Japan, was built as a basis to establish a digital twin of the SIS. Spatially varying filtering parameters and grid resolutions were applied to facilitate the robust and accurate simulation of coastal and oceanic processes even under varying extreme conditions. The modeling results were validated using observational datasets from forty-two tidal stations, one mooring system, and thirteen water thermometers. The results represented tidal variations, with NRMSE values below 0.15 and R2 values exceeding 0.87 at all tidal stations. The NRMSE and R2 values for currents were approximately 0.14 and 0.76, respectively. The model reproduced the extreme storm surge event causing a sea level rise of 1.5 m near Osaka City resulting from Typhoon Jebi in 2018. The model was shown to enable analyses of complex circulations and hazards in the SIS by accurately replicating barotropic and baroclinic processes. After additional modules are added, this model will serve as a basis for constructing a digital twin of the SIS.
This study aims to quantitatively assess the impacts of climate change on the flood-prone risk areas in Davao Oriental, Philippines for the years 2030, 2050, and 2100 in comparison with the present ...situation by identifying flood risk zones based on multisource data, including rainfall, slope, elevation, drainage density, soil type, distance to the main channel, and population density. The future temperatures and rainfall projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5) predictions of the Intergovernmental Panel on Climate Change (IPCC) were used. The future temperatures from the CMIP5 predictions showed that Davao Oriental should experience approximately 1 °C and 3 °C increases under the Representative Concentration Pathway (RCP)4.5 and RCP8.5 scenarios, respectively, while the rainfall should slightly increase in the coming years. Among the 39 general circulation models (GCMs) available from CMIP5, the GFDL-ESM2M model showed good agreement with the observed rainfall dataset at the local stations. The intensity of rainfall should increase approximately 69% in the future, resulting in an increase in the magnitude of the floods. The resulting flood risk map shows that 95.91% of Davao Oriental is presently under the low and moderate flood risk categories, and those categories should slightly decrease to 95.75% in the future. The high and very high flood risk areas cover approximately 3% of the province at present and show no dramatic change in the future. Presently, 28 out of the 183 barangays (towns) are at high and very high risks of floods, whereas in the coming years, only one barangay will be added to the very high risk of floods. These barangays under the high and very high categories of flood risk are primarily situated on riversides and coastal areas. Thus, immediate actions from decision-makers are needed to develop a community-based disaster risk plan under the future conditions.
PDF
