Randolphpadilla5146

All nuclear energy producing nations face a common challenge associated with the long-term solution for their used nuclear fuel. After decades of research, many nuclear safety agencies worldwide agree that deep geological repositories (DGRs) are appropriate long-term solutions to protect the biosphere. The Canadian DGR is planned in either stable crystalline or sedimentary host rock (depending on the final site location) to house the used nuclear fuel in copper-coated used fuel containers (UFCs) surrounded by highly compacted bentonite. The copper-coating and bentonite provide robust protection against many corrosion processes anticipated in the DGR. However, it is possible that bisulfide (HS-) produced near the host rock-bentonite interface may transport through the bentonite and corrode the UFCs during the DGR design life (i.e., one million years); although container performance assessments typically account for this process, while maintaining container integrity. Because the DGR design life far exceeds those of practical experimentation, there is a need for robust numerical models to forecast HS- transport. In this paper we present the development of a coupled 3D thermal-hydraulic-chemical model to explore the impact of key coupled physics on HS- transport in the proposed Canadian DGR. These simulations reveal that, although saturation delayed and heating accelerated HS- transport over the first 100s and 10,000s of years, respectively, these times of influence were small compared to the long DGR design life. Consequently, the influence from heating only increased total projected HS- corrosion by less then 20% and the influence from saturation had a negligible impact ( less then 1%). By comparing the corrosion rate results with a simplified model, it was shown that nearly-steady DGR design parameters governed most of the projected HS- corrosion. Therefore, those parameters need to be carefully resolved to reliably forecast the extent of HS- corrosion.Soil moisture (SM) and groundwater (GW) depletion triggered by anthropogenic and natural climate change are influencing food security via crop production per capita decrease in the Nile River Basin (NRB). However, to the best of our understanding, the causes and impact of SM and GW depletion have not been studied yet comprehensively in the NRB. In this study, GW is derived from the Gravity Recovery and Climate Experiment (GRACE) mission, and SM was estimated using the Triple Collocation Analysis (TCA). SM/GW depletion causes were evaluated via the Land Use Land Cover (LULC) and rainfall/temperature change analysis, whereas impact analysis focused on crop production per capita reduction (food insecurity) during SM depletion. The major findings of this study are 1) TCA analyzed SM show a decreasing trend (-0.06 mm/yr) in agricultural land while increasing (+0.21 mm/yr) in forest land, 2) LULC analysis indicated a vast increment of agricultural land (+9%) and bareland (+9%) although the decreasing pattern of forest (-1.5%) and shrubland (-6.9%) during 1990-2019; 3) the impact of SM depletion on crop production per capita caused food insecurity during a drought year, 4) agriculture drought indices and crop production per capita show high correlations (R2 = 0.86 to 0.60) demonstrated that Vegetation Supply Water Index (VSWI) could provide strategic warning of drought impacts on rainfed agricultural regions. In conclusion, SM and GW depletions are mainly caused by human-induced and climate change factors imposing food insecurity challenges in the NRB coupled with increasing temperature and excessive water extraction for irrigation. Therefore, it is highly recommended to rethink and reverse SM/GW depletion causing factors to sustain food security in NRB and similar basins.The spatial structures of chiral pesticide enantiomers can affect their activity, toxicity and behavior, thereby altering exposure risk. Identifying enantiomer differences and developing high-efficiency green enantiopure pesticide is an important strategy for reducing the negative effects of pesticides. In this study, after confirming the absolute configuration of pydiflumetofen enantiomers, fungicidal activity evaluation indicated that the activity of S-(+)-pydiflumetofen was 81.3-421 times higher than R-(-)-pydiflumetofen on three kinds of phytopathogens that control Fusarium wilt (Fusarium spp.), Alternaria rot (Alternaria alternata) and Southern blight (Sclerotinia rolfsii), which might be caused by the stronger binding ability of S-(+)-pydiflumetofen with the active site of the target protein. The coexistence of R-(-)-pydiflumetofen would enhance the toxicity of S-(+)-pydiflumetofen on zebrafish through synergistic effect. Low-activity R-(-)-pydiflumetofen was preferentially dissipated in soybean, soybean plants, cabbage and celery, which was opposite in soil. The persistence of S-(+)-pydiflumetofen in crops and degradability in soil were advantageous for pesticide effects and environmental protection. Based on the maximum residue limit (MRL) and hazard quotient (HQ), the dietary risks were determined to be acceptable for all crops. Thus, developing enantiopure S-(+)-pydiflumetofen products might be a high-efficiency and low-risk strategy, and more studies should be conducted in this aspect.Cd long-term immobilization by biochar and potential risk in soils with different pH were quantified under a combined artificial aging, which simulated five years of aging in the field based on local climate. Two biochars (original and KMnO4-modified) and five soils with different pH were tested, and an improved three-layer mesh method was employed in this study. Five aging cycles were carried out (Cycle 1-Cycle 5), and each aging cycle quantitatively simulated 1 year of natural aging. As the aging time increased, Cd leaching loss in all soils gradually increased from Cycle 1 to Cycle 5; for relatively stable Cd fraction, it decreased firstly and then stabilized in acidic and neutral soils (S1-S4), while it decreased firstly and then increased in alkaline soil (S5). Biochars significantly promoted Cd immobilization in strongly acidic soil (S1) by increasing relatively stable fractions and decreasing leaching loss. For weakly acidic and neutral soils (S2-S4), although biochars still had positive effects, the immobilization effects were weakened to certain extents compared with S1. The percentage of Cd leaching loss decreased by 19.12% in strongly acidic soil (S1) and by 1.12-11.35% in weakly acidic and neutral soils (S2-S4) after modified biochar treatment. For alkaline soil (S5), the application of biochars had negative effects on Cd immobilization by decreasing relatively stable fractions and increasing leaching loss, and posed risks to the environment. For strongly acidic soil (S1) and weakly acidic and neutral soils (S2-S4), the percentages of relatively stable fractions increased from 6.09-19.93% to 24.98-36.70% after modified biochar treatment. However, for alkaline soil, the percentage of relatively stable fractions decreased from 55.27% to 53.93% after biochar treatment. The more acidic the soil, the more effective the Cd immobilization by biochar. Biochars with high pH level are not suitable for the remediation of alkaline Cd contaminated soil.Solidification/stabilization (S/S) is an option for the treatment of electrolytic manganese residue (EMR). Basic burning raw material (BRM) could successfully solidify/stabilize EMR, though heavy metals S/S mechanism and long-term stability remain unclear. Herein, Mn2+ and NH4+ S/S behavior, hydrated BRM and S/S EMR characterization, Mn2+ long-term leaching behavior, phase and morphology changes for long-term leaching were discussed in detail to clarify these mechanisms. Mn2+ and NH4+ leaching concentrations as well as pH value in S/S EMR were respectively 0.02 mg/L, 0.68 mg/L and 8.75, meeting the regulations of Chinese standard GB 8978-1996. Long-term stability of EMR was significantly enhanced after S/S. Mn2+ leaching concentration, Mn2+ migration, Mn2+ cumulative release, Mn2+ apparent diffusion coefficient and conductivity of EMR reduced to 0.05 mg/L, 5.5 × 10-6 mg/(m2·s), ~ 9 mg/m2, 6.30 × 10-15 m2/s and 435 μs/cm. Mechanism studies showed that the hydration of BRM forms OH-, calcium silicate hydrate gels (C-S-H) and ettringite. Therefore, during S/S process, NH4+ was escaped as NH3, Mn2+ was solidified/stabilized as tephroite (Mn2SiO4), johannsenite (CaMnSi2O6) and davreuxite (MnAl6Si4O17(OH)2), and Pb2+, Cu2+, Ni2+, Zn2+ were solidified/stabilized by C-S-H and ettringite via substitution and encapsulation. This study provides a good choice for EMR long-term stable storage.Heterogeneous land cover affects near-surface heat and humidity distribution in urban areas. Effective land cover arrangements can create a more sustainable local thermal environment. However, spatial differentiation in neighborhood climates and their spatial response range to the surrounding land cover composition (LCC) in high-density urban environments remains unclear. In this study, field monitoring of the air temperature (Ta) and relative humidity (Rh) was conducted in summer (August 2016) and winter (December 2016 and January 2017) in a neighborhood in Beijing, China. A multi-radius approach was developed to quantify the effective response range of Ta and Rh at unshaded measuring points to the surrounding LCC. Our results demonstrated that the (1) spatial distribution of Ta and Rh in a typical neighborhood varies significantly in both summer and winter and is dependent on the local land cover; (2) Ta at measurement points generally increases with growing surrounding vegetation coverage and decreases with less impervious pavement and building coverage, whereas the opposite applies to Rh; (3) response of Ta and Rh to land cover composition is spatially dependent; and (4) Ta and Rh have an effective response range of up to 200-m to surrounding vegetation coverage in both seasons, whereas their response range to pavement coverage is 150- and 100-m in summer and winter, respectively. Overall, LCC within a radius of 100-150-m has a significant impact on the Ta and Rh of the measuring points in a high-density urban neighborhood. These findings elucidate the spatial response of a neighborhood climate to surrounding land cover and demonstrate that landscape infrastructure intervention is an effective means of improving urban thermal environments.Terrestrial evapotranspiration (ET) refers to a key process in the hydrological cycle by which water is transferred from the Earth's surface to lower atmosphere. With spatiotemporal variations, ET plays a crucial role in the global ecosystem and affects vegetation distribution and productivity, climate, and water resources. China features a complex, diverse natural environment, leading to high spatiotemporal heterogeneity in ET and climatic variables. However, past and future ET trends in China remain largely unexplored. Thus, by using MOD16 products and meteorological datasets, this study examined the spatiotemporal variations of ET in China from 2000 to 2019 and analyzed what is behind changes, and explored future ET trends. selleck Climate variation in China from 2000 to 2019 was statistically significant and had a remarkable impact on ET. Average annual ET increased at a rate of 5.3746 mm yr-1 (P less then 0.01) during the study period. The main drivers of the trend are increasing precipitation and wind speed. The increase in ET can also be explained to some extent by increasing temperature, decreasing sunshine duration and relative humidity.