The redox chemistry of Pu(V)O₂⁺ interaction with common mineral surfaces in dilute solutions and seawater     

Wendy L. Keeney-kennicutt  John W. Morse 《Geochimica et cosmochimica acta》1985,49(12):2577-2588

It has long been recognized that the Pu⁴⁺ ion can be readily adsorbed on solid surfaces, but it has been assumed that the generally more abundant Pu(V)O₂⁺ ion should have little affinity for surfaces. Our results indicate that Pu(V)O₂⁺ can be adsorbed from dilute solutions and seawater on goethite, aragonite, calcite, and δ-MnO₂. Adsorption on δ-MnO₂ is severely depressed in seawater, probably as a result of site competition with seawater cations.The sorption behavior of PuO₂⁺ is influenced by oxidation-reduction reactions occurring on the mineral surfaces. Adsorption on δ-MnO₂ results in oxidation of adsorbed Pu(IV) and Pu(V) to Pu(VI). However, adsorption on goethite results in a reaction in which Pu(IV) and Pu(VI) are formed on the mineral surface. The Pu(VI) is slowly reduced to Pu(IV), leaving Pu(IV) as the dominant surface Pu species. This reaction can be photochemically catalyzed. PuO₂⁺ adsorbed on carbonate minerals behaves similarly to Np(V)O₂⁺ and undergoes little change in oxidation state after adsorption.  相似文献   

Online Survey of Heterogeneous Users and Their Usage of the Interactive Mapping Platform WorldMap   总被引：1，自引：0，他引：1  

Alenka Poplin  Wendy Guan  Ben Lewis 《The Cartographic journal》2017,54(3):214-232

This article reports on the results of an online survey with 290 heterogeneous users of the interactive mapping platform WorldMap and provides insights into problems faced by such users. Heterogeneous users are users with a variety of GIS skills, educational background, gender, and age categories. We investigate how they interact with online maps and analyse their experience. WorldMap represents as a case study of an online mapping platform which aims to serve researchers and users across disciplines in viewing and creating online interactive maps. We concentrate on operations that are perceived as difficult and very difficult by the majority of users as well as operations that are rarely used. Our aim is to contribute to the discussions on how to improve the design of online GIS-based mapping platforms. We conclude the paper with reflections on the results of our study and ideas for further research.  相似文献   

Household Water Insecurity in the Global North: A Study of Rural and Periurban Settlements on the Texas–Mexico Border     

Wendy Jepson  Emily Vandewalle 《The Professional geographer》2016,68(1):66-81

This article examines household-level characteristics that predict water insecurity in low-income rural and periurban communities on the Texas–Mexico border. We employ two logistic regression models (binary and ordered) to identify household characteristics that are more likely to result in water insecurity. Our analyses yielded unexpected findings: Whereas socioeconomic factors are weak predictors, immigration status of household members is a significant variable that contributes to household water insecurity. Policymakers need to pay more attention to marginalized communities as “universal” water access still leaves populations without adequate, reliable, and affordable water in the Global North.  相似文献   

Combining threat and efficacy messaging to increase public engagement with climate change in Beijing,China     

Wen Xue  Donald W. Hine  Anthony D. G. Marks  Wendy J. Phillips  Patrick Nunn  Shouying Zhao 《Climatic change》2016,137(1-2):43-55

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Distribution and chemistry of manganese,iron, and suspended particulates in Orca Basin     

John H. Trefry  Bob J. Presley  Wendy L. Keeney-Kennicutt  Robert P. Trocine 《Geo-Marine Letters》1984,4(2):125-130

The intense halocline and redoxcline in the Orca Basin, northwest Gulf of Mexico, induce dramatic water column profiles for manganese, iron, and suspended particulates. Within a 17 m interval, the salinity of the basin water increases from 66 to 260 & permil and dissolved oxygen decreases to zero. Midway through this transition zone, concentrations of suspended matter peak at 900 g/liter. Dissolved iron and manganese concentrations in the anoxic brine increase from oceanic values to maxima of 1.6 and 22 mg/liter, respectively. Upward migration of dissolved manganese from the brine leads to production of manganese-rich particles in the slightly oxygenated overlying water.  相似文献   

Soil moisture response to white ash mortality following emerald ash borer invasion     

Wendy M. Robertson  Molly Robinett  Deborah G. McCullough 《Environmental Earth Sciences》2018,77(9):356

Emerald ash borer (EAB) (Agrilus planipennis Fairmaire), an invasive forest insect first identified in southeastern Michigan in 2002, is established in at least 32 US states and three Canadian provinces. Ash (Fraxinus spp.) mortality rates in some forested areas exceed 90%, but to date, little is known about the potential effects of EAB-caused ash mortality on hydrological processes. More broadly, there is a need for information on the timing and magnitude of soil moisture response to species-specific mortality of overstory vegetation in deciduous forest systems. Soil moisture was examined in 28 forested sites where 0–100% of the white ash basal area (Fraxinus americana L.) was killed by EAB. Synoptic measurements of near-surface (0–6 cm depth) soil moisture were collected from 112 plots (18 m radius) within the sites. Three plots were also instrumented with soil moisture sensors at 10 and 25 cm depth to log hourly measurements from May to October. Synoptic data showing white ash mortality and soil moisture were positively correlated in the 34 plots with ≥?5% mortality (by total basal area). In the intensively monitored plots, volumetric soil moisture declined from 37 to 16% between July and September where white ash mortality was low (0.6% of basal area killed), but remained near field capacity (~?30%) throughout the monitoring period in the high mortality plot (8.6% of basal area killed), meriting further investigation to assess effects of white ash mortality on evapotranspiration and soil moisture dynamics in heterogeneous upland forests. Altered soil moisture may have implications for regrowth dynamics, infiltration/runoff partitioning, and nutrient cycling, but additional study to quantify the extent and duration of EAB-related ash mortality on hydrology at the plot and watershed scale is necessary.  相似文献   

Formation process of a large paleolandslide-dammed lake at Xuelongnang in the upper Jinsha River,SE Tibetan Plateau: constraints from OSL and <Superscript>14</Superscript>C dating     

Jian Chen  Wendy Zhou  Zhijiu Cui  Weichao Li  Saier Wu  Junxue Ma 《Landslides》2018,15(12):2399-2412

A large number of the landslide dams located on the major rivers at the southeastern margin of the Tibetan Plateau have been previously identified through remote sensing analysis and field investigations. The Xuelongnang paleolake was one of the lakes formed by these landslide dams in the upper Jinsha River, where the association of a relict landslide dam, lacustrine sediment, and outburst sediment is well preserved. This preservation provides an opportunity to better understand the formation, evolution, and longevity of a large landslide-dammed lake in the upper Jinsha River. It was inferred that the Xuelongnang dammed lake may have been formed by an earthquake-induced paleoavalanche. The surface area of the lake at its peak was estimated at 7.0?×?10⁶ m², and the corresponding volume was approximately 3.1?×?10⁸ m³. Two outburst flood events were determined to have occurred during the life span of the lake. Based on the 18 ages obtained from optically stimulated luminescence (OSL) and carbon-14 (¹⁴C) dating combined with stratigraphic sequences observed in the field, the paleolandslide-dammed lake was formed at approximately 2.1 ka and subsequently breached locally. The dammed lake was sustained for a period of some 900 years based on the chronological constraining. This study confirms that a major landslide-dammed lake can be sustained for at least hundreds of years and breached by several dam breaks in multiple periods, which contributed to the preservation of the knickpoints at millennial scale along the major rivers in the study area.  相似文献   

Analytical methods to estimate the hydraulic conductivity of jointed rocks     

Zoorabadi  Mahdi  Saydam  Serkan  Timms  Wendy  Hebblewhite  Bruce 《Hydrogeology Journal》2022,30(1):111-119

Hydrogeology Journal - The hydraulic conductivity of jointed rocks is one of the main input parameters to predict water inflow to engineering structures that are located in the jointed rocks....  相似文献   

Dynamic hazard assessment of group-occurring debris flows based on a coupled model     

Nie  Yinping  Li  Xiuzhen  Zhou  Wendy  Xu  Ruichi 《Natural Hazards》2021,106(3):2635-2661

Natural Hazards - A scientific hazard zoning of debris flows can ensure that human activities are not performed therein, thereby reducing economic loss as much as possible. In this study, by...  相似文献   

Global scale uniformitarianism and catastrophism dictated by crust-to-core volatile cycles     

Hokwang Mao  Yang Ding  Duckyoung Kim  Qingyang Hu  Jin Liu  Liuxiang Yang  Wenge Yang  Li Zhang  Wendy L. Mao 《《地质学报》英文版》2018,92(Z1):8-8

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