A σ-coordinate transport model coupled with rotational boussinesq-type equations

This paper describes a σ-coordinate scalar transport model coupled with a Boussinesq-type hydrodynamic model. The Boussinesq model has the ability to calculate both three-dimensional velocity distributions and the water surface motion. To capture ‘dispersion’ processes in open channel flow, horizontal vorticity effects induced by a bottom shear stress are included in the Boussinesq model. Thus, a reasonable representation of vertical flow structure can be captured in shallow and wavy flow fields. To solve the coupled Boussinesq and scalar transport system, a finite-volume method, based on a Godunov-type scheme with the HLL Riemann solver, is employed. Basic advection and advection–diffusion numerical tests in a non-rectangular domain were carried out and the computed results show good agreement with analytic solutions. With quantitative comparisons of dispersion experiments in an open channel, it is verified that the proposed coupled model is appropriate for both near and far field scalar transport predictions. From numerical simulations in the surf zone, physically reasonable results showing expected vertical variation are obtained.     

Arsenic mobility in the amended mine tailings and its impact on soil enzyme activity

The objectives of this study were to elucidate the effects of soil amendments [Ferrous sulfate (Fe^II), red mud, Fe^II with calcium carbonate (Fe^II/L) or red mud (RM/F), zero-valent iron (ZVI), furnace slag, spent mushroom waste and by-product fertilizer] on arsenic (As) stabilization and to establish relationships between soil properties, As fractions and soil enzyme activities in amended As-rich gold mine tailings (Kangwon and Keumkey). Following the application of amendments, a sequential extraction test and evaluation of the soil enzyme activities (dehydrogenase and β-glucosidase) were conducted. Weak and negative relationships were observed between water-soluble As fractions (As_WS) and oxalate extractable iron, while As_WS was mainly affected by dissolved organic carbon in alkaline tailings sample (Kangwon) and by soil pH in acidic tailings sample (Keumkey). The soil enzyme activities in both tailings were mainly associated with As_WS. Principal component and multiple regression analyses confirmed that As_WS was the most important factor to soil enzyme activities. However, with some of the treatments in Keumkey, contrary results were observed due to increased water-soluble heavy metals and carbon sources. In conclusion, our results suggest that to simultaneously achieve decreased As_WS and increased soil enzyme activities, Kangwon tailings should be amended with Fe^II, Fe^II/L or ZVI, while only ZVI or RM/F would be suitable for Keumkey tailings. Despite the limitations of specific soil samples, this result can be expected to provide useful information on developing a successful remediation strategy of As-contaminated soils.     

Growth dynamics of the seagrass <Emphasis Type="Italic">Halophila nipponica</Emphasis>, recently discovered in temperate coastal waters of the Korean peninsula

Seagrass species in the genus Halophila are usually distributed in tropical or subtropical areas, but a Halophila species identified as H. nipponica was first observed in temperate coastal regions of Korea in 2007. Since this species mainly occurs in warm temperate regions influenced by warm currents, we hypothesized that H. nipponica may exhibit different growth patterns from those of other temperate seagrass species in Korea, instead showing similar growth dynamics to tropical/subtropical species. The growth and morphology of H. nipponica in relation to coincident measurements of environmental factors were investigated from July 2008 to September 2009 to examine the growth dynamics of this species. Water temperature at the study site ranged from 9.7°C in January to 25.1°C in August. Shoot density, biomass, and productivity exhibited significant seasonal variation, increasing during summer and decreasing during winter. Productivity was severely restricted to nearly ceasing at water temperatures less than 15°C, and winter minimum growth lasted until May. The optimal temperature for H. nipponica growth was approximately 25°C, which was the maximum water temperature at the study site, and no growth reduction in high summer water temperature was observed. Thus, H. nipponica on the temperate coast of Korea exhibited a distinctly different growth pattern from those of temperate seagrass species in Korea, which have shown great reductions in growth at water temperatures higher than 20°C. Higher below- to above-ground ratio and leaf burial into sediments with shorter leaf petioles during winter might be overwintering strategies in this species. The growth patterns of H. nipponica at the study site imply that this species still possess the tropical characteristics of the genus Halophila.     

Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing

Journal of Material Cycles and Waste Management - Organic binders that are used in sand casting emit high amounts of hazardous pollutants and volatile organic compounds during the casting process....     

Evaluation of Korean recycled aggregates as backfilling underground power system considering particle breakage effect

Journal of Material Cycles and Waste Management - Attempts have been made to address the strict regulations on eco-friendly construction and recycle aggregate resources, encouraging researchers to...     

Recovery of Pd as PdO from Pd/SiO2 catalyst by leaching using hydrochloric acid

Journal of Material Cycles and Waste Management - The recovery of Pd from spent catalysts has been gaining attention due to its high economic value and limited availability in nature. To recover...     

Spent Coffee Grounds and Coffee Silverskin as Potential Materials for Packaging: A Review

Journal of Polymers and the Environment - Coffee is a widely enjoyed beverage and one of the world’s most traded commodities. However, it also generates large amounts of bio-based waste...     

Numerical and field investigation of enhanced in situ denitrification in a shallow-zone well-to-well recirculation system

This study investigated efficiency of in situ enhanced biological denitrification of nitrate-contaminated groundwater which employs a well-to-well circulation in a shallow zone where oxygen might give an adverse affect on the denitrification processes. The numerical model developed for the efficiency test included sequential aerobic and nitrate-based respiration, multi-Monod kinetics of reactive components, growth and decay of biomass, and denitrification inhibition associated with the presence of oxygen. Moreover, reaction kinetics for production of toxic intermediates such as nitrite and nitrous oxide were also included in the model. The developed model was applied to the analysis of enhanced in situ denitrification using an injection/extraction well pair. To evaluate the relative remediation effectiveness, comparisons were made between a continuous fumarate injection test (CFIT) system and a pulsed fumarate injection test (PFIT) system, where both systems had the same total fumarate mass injected into the aquifer. The PFIT system was preferable to the CFIT system because of the high possibility of occurrence of clogging in the latter case at the injection well, with no other significant advantages found in either the CFIT or the PFIT system. Accordingly, this developed numerical model is useful to predict and evaluate an in situ bioremediation by denitrification in aquifers.     

What makes affirmative action‐based hiring decisions seem (un)fair? A test of an ideological explanation for fairness judgments

Studies show that Whites tend to show the lowest level of support for affirmative action (AA) policies. Opponents of AA often argue that this is because it violates principles of meritocracy. However, self‐interest (based on social identification with those adversely affected) could also explain their opposition. In three studies, we varied whether an Asian or White male is adversely affected by AA to test another explanation; namely, that Whites' fairness judgments are based on both the adversely affected person's race and the fairness evaluator's ideological beliefs. Although we found some support for the meritocratic explanation, this was not sufficient to explain why Whites view AA as (un)fair. Instead, we found strong support for our prediction that Whites who are opposed to equality perceive more unfairness when a White (vs. Asian) was harmed by AA, whereas Whites who endorse egalitarian ideologies perceive the opposite. This finding suggests that neither self‐interest nor meritocratic explanations can fully account for Whites' opposition to AA. Copyright © 2014 John Wiley & Sons, Ltd.     

A review of the health impacts of barium from natural and anthropogenic exposure

There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food.