Segmented YSO scintillation detectors as a new β-implant detection tool for decay spectroscopy in fragmentation facilities

A newly developed segmented YSO scintillator detector was implemented for the first time at the RI-beam Factory at RIKEN Nishina Center as an implantation-decay counter. The results from the experiment demonstrate that the detector is a viable alternative to conventional silicon-strip detectors with its good timing resolution and high detection efficiency for β particles. A Position-Sensitive Photo-Multiplier Tube (PSPMT) is coupled with a 48 × 48 segmented YSO crystal. To demonstrate its capabilities, a known short-lived isomer in Ni and the β decay of Co were measured by implanting those ions into the YSO detector. The half-lives and γ-rays observed in this work are consistent with the known values. The β-ray detection efficiency is more than 80 % for the decay of Co.The present experiment was carried out at the RI Beam Factory operated by RIKEN Nishina Center, RIKEN and CNS, University of Tokyo. This research was supported in part by the Offce of Nuclear Physics, U.S. Department of Energy under Award No. DE-FG02-96ER40983 (UTK)

Toward evaluating the effect of climate change on investments in the water resources sector: insights from the forecast and analysis of hydrological indicators in developing countries

The World Bank has recently developed a method to evaluate the effects of climate change on six hydrological indicators across 8951 basins of the world. The indicators are designed for decision-makers and stakeholders to consider climate risk when planning water resources and related infrastructure investments. Analysis of these hydrological indicators shows that, on average, mean annual runoff will decline in southern Europe; most of Africa; and in southern North America and most of Central and South America. Mean reference crop water deficit, on the other hand, combines temperature and precipitation and is anticipated to increase in nearly all locations globally due to rising global temperatures, with the most dramatic increases projected to occur in southern Europe, southeastern Asia, and parts of South America. These results suggest overall guidance on which regions to focus water infrastructure solutions that could address future runoff flow uncertainty. Most important, we find that uncertainty in projections of mean annual runoff and high runoff events is higher in poorer countries, and increases over time. Uncertainty increases over time for all income categories, but basins in the lower and lower-middle income categories are forecast to experience dramatically higher increases in uncertainty relative to those in the upper-middle and upper income categories. The enhanced understanding of the uncertainty of climate projections for the water sector that this work provides strongly support the adoption of rigorous approaches to infrastructure design under uncertainty, as well as design that incorporates a high degree of flexibility, in response to both risk of damage and opportunity to exploit water supply 'windfalls' that might result, but would require smart infrastructure investments to manage to the greatest benefit

Winter Rye Cover Crop Biomass Production, Degradation, and Nitrogen Recycling

Winter rye (Secale cereale L.) cover crop (RCC) use in corn (Zea mays L.) and soybean [Glycine max. (L.) Merr.] production can alter N dynamics compared to no RCC. The objectives of this study were to evaluate RCC biomass production (BP) and subsequent RCC degradation (BD) and N recycling in a no-till corn–soybean (CS) rotation. Aboveground RCC was sampled at spring termination for biomass dry matter (DM), C, and N. To evaluate BD and remaining C and N, RCC biomass was put into nylon mesh bags, placed on the soil surface, and collected multiple times over 105 d. Treatments included rye cover crop following soybean (RCC-FS) and corn (RCC-FC), and prior-year N applied to corn. Overall, the RCC BP and N was low due to low soil profile NO3–N. Across sites and years, the greatest BP was with RCC-FC that received 225 kg N ha–1 (1280 kg DM ha–1), with similar N uptake as with RCC-FS (27 kg N ha–1). The RCC biomass and N remaining decreased over time following an exponential decay. An average 62% biomass with RCC-FS and RCC-FC degraded after 105 d; however, N recycled was greater with RCC-FS than RCC-FC [22 (80%) vs. 14 (64%) kg N ha–1, respectively], and was influenced by the RCC C/N ratio. The RCC did not recycle an agronomically meaningful amount of N, which limited N that could potentially be supplied to corn. Rye cover crops can conserve soil N, and with improved management and growth, recycling of crop-available N should increase

Evaluating stream water quality through land use analysis in two grassland catchments: impact of wetlands on stream nitrogen concentration.

We evaluated the impacts of natural wetlands and various land uses on stream nitrogen concentration in two grassland-dominated catchments in eastern Hokkaido, Japan. Analyzing land use types in drainage basins, measuring denitrification potential of its soil, and water sampling in all seasons of 2003 were performed. Results showed a highly significant positive correlation between the concentration of stream NO3–N and the proportion of upland area in drainage basins in both catchments. The regression slope, which we assumed to reflect the impact on water quality, was 24% lower for the Akkeshi catchment (0.012 ± 0.001) than for the Shibetsu catchment (0.016 ± 0.001). In the Akkeshi catchment, there was a significant negative correlation between the proportion of wetlands in the drainage basins and stream NO3–N concentration. Stream dissolved organic nitrogen (DON) and carbon (DOC) concentrations were significantly higher in the Akkeshi catchment. Upland and urban land uses were strongly linked to increases in in-stream N concentrations in both catchments, whereas wetlands and forests tended to mitigate water quality degradation. The denitrification potential of the soils was highest in wetlands, medium in riparian forests, and lowest in grasslands; and was significant in wetlands and riparian forests in the Akkeshi catchment. The solubility of soil organic carbon (SOC) and soil moisture tended to determine the denitrification potential. These results indicate that the water environment within the catchments, which influences denitrification potential and soil organic matter content, could have caused the difference in stream water quality between the two catchments

Hydrological process controls on nitrogen export during storm events in an agricultural watershed

The dynamic characteristics of nitrogen (N) and suspended solids (SS) were investigated in stream water during four storm events in 2003 at the Shibetsu watershed, eastern Hokkaido, Japan. Analysis showed that total nitrogen (TN), nitrate-N (NO^[-]_[3] -N), dissolved organic nitrogen (DON), particulate nitrogen (PN), and SS concentrations all peaked sharply during the rising limb of the discharge hydrograph, but peaks in PN and SS were more significant than that of dissolved N. PN and SS consistently displayed clockwise hysteresis with higher concentrations during rising flows, whereas NO^[-]_[3]-N and DON showed different patterns among storms depending on the antecedent soil moisture. An M (V) curve, defined as the nutrient mass distribution vs. the volume of discharge, showed that a "first flush" of PN, NO^[-]_[3]-N, DON and SS was observed, however, the distribution of nutrient loads in the discharge was different. PN and SS had a shorter flushing characteristic time constant (t_[1/e], defined as the time interval required for a decline in nutrient concentrations in discharge water to e^[-1] (37%) of their initial concentrations) but contributed 80% of fluxes during the first 50% of the discharge, while longer flush time (t_[1/e]) of NO^[-]_[3]-N and DON with slowly decreased concentrations led to half loads during the recession of the discharge. These data indicate that the flush mechanisms might be distinguished between particulate nutrients and dissolved N. Analysis showed that the concentrations of PN and SS derived from soil erosion were related to surface runoff. In contrast, NO^[-]_[3]-N originated from the near-surface soil layer associated with the rising shallow ground water table and mainly flushed with subsurface runoff. Different flushing mechanisms implied that different watershed best management practices should be undertaken for effectively mitigating water quality degradation