Mechanisms of pore water organic matter adsorption to montmorillonite

The extent and mechanisms of adsorption of marine pore water organic matter to montmorillonite were studied in a series of batch and sequential adsorption experiments. Pore water natural organic matter (pNOM) and easily extracted natural organic matter (eNOM) were collected from Liberty Bay (Puget Sound, WA, USA) sediments. The pNOM and eNOM were each divided into two size fractions using a 1000 D ultrafilter. Batch adsorption isotherms were approximately linear, and the >1000 D fractions of both pNOM and eNOM had larger partition coefficients (K_d) than the <1000 D fractions. A two-component fit of the sequential adsorption data indicated that pNOM and eNOM contained a similar amount of NOM (30%) that was not surface reactive toward montmorillonite. After correcting the batch adsorption K_ds for the non-reactive components, the K_ds estimated by batch and sequential adsorption were identical (2.7 l/kg for >1000 D pNOM and eNOM, and 1.6 l/kg for <1000 D pNOM and eNOM). Mechanisms of adsorption were investigated by systematically changing conditions (pH, temperature and ionic composition) of >1000 D fractions during batch isotherm experiments. Adsorption of NOM was found to decrease with increased temperature, suggesting that hydrophobic effects were not the dominant adsorption mechanisms in this system. Ion exchange was also not an important adsorption mechanism because adsorption increased with ionic strength. The observed enhancement in adsorption with ionic strength indicated that van der Waals interactions were important in the adsorption of NOM. Ligand exchange was found to be a significant mechanism since the presence of SO₄²⁻ in solution reduced the amount of NOM adsorbed. Ca²⁺ enhanced adsorption slightly more than Na⁺, suggesting that cation bridging was involved. The relative contributions of van der Waals interactions, ligand exchange and cation bridging were estimated to be approximately 60%, 35% and 5%, respectively, for adsorption of NOM in a CaCl₂ solution.     

Paleoecological and biogeographical implications of late Pleistocene noble marten (Martes americana nobilis) in eastern Washington State, USA

A mandible identified as noble marten (Martes americana nobilis) recovered from sediments dating to 11,800 cal yr BP and a humerus identified as M. a. cf. nobilis recovered from sediments dating from 13,100 to 12,500 cal yr BP at the Marmes Rockshelter archaeological site in southeastern Washington represent the first record of this taxon in the state. Mammalian taxa associated with the Marmes Rockshelter noble marten represent a diversity of open mesic habitats corroborating earlier analyses of other records of the noble marten in the western United States and exemplify how paleozoologists determine the ecology and environmental predilections of extinct taxa. The recovery site represents the topographically lowest record of this species in western North America and the farthest north record in the United States. Future research should examine known late-Quaternary Martes spp. remains from British Columbia and Alberta to fill in the 2200-km geographic gap in the known distribution of this taxon between a record in the northern Yukon and those in the western United States, and to refine our knowledge of noble marten paleoecology.     

Terminal Pleistocene change in mammal communities in southeastern Washington State,USA

Small mammal communities in western North America experienced declines in taxonomic richness across the late Pleistocene to Holocene transition (PHT), a recent natural global warming event. One community also experienced a decline in evenness and others replaced one species with a congener. Variability in response of small mammal communities to PHT warming is apparent. At the presently arid and xeric Marmes site in the Columbia Basin of southeastern Washington State, megafauna were absent by about 13,000 cal yr BP, evenness of small mammals declined about 11,700 cal yr BP and again about 11,400 cal yr BP whereas richness declined about 11,400 cal BP. Regional faunal turnover was, however, minimal among small-bodied taxa. Local mammal communities are depauperate as a result of megafaunal extinctions and subsequent decreases in small-mammal richness and evenness. The latter chronologically corresponds with a decrease in primary productivity driven by increasing warmth and aridity. More faunas must be studied in order to fully document the range of variability in the responses of mammalian communities to PHT warming. Documentation of patterns in those responses will facilitate understanding and enhance predictive accuracy with respect to responses of mammalian communities to modern global warming.     

Geographers in the U.S. Government in Washington,DC, during World War II

Geographers in Washington, DC, during World War II and the agencies in which they worked are recalled through the naming of geographers engaged in wartime work during this seminal period in the development of the geography profession in the United States. The five agencies then employing the largest number of geographers were the Research and Analysis Branch of the Office of Strategic Services, the Topographic Branch of the Military Intelligence Division of the War Department, the Board of Economic Warfare (later the Foreign Economic Administration), the Board on Geographic Names, and the Office of the Geographer, Department of State. The impacts of this period on individual geographers, the professional organization of geographers, cartography, higher education, and the government are suggested.     

Numerical issues in computing inundation areas over natural terrains using Savage-Hutter theory

When characterizing geologic natural hazards, specifically granular flows including pyroclastic flows, debris avalanches and debris flows, perhaps the most important factor to consider is the area of inundation. One of the key parameters demarcating the leading edge of inundation is the run-out distance. To define the run-out distance, it is necessary to know when the flow stops. Numerical experiments are presented for determining a stopping criterion and exploring the suitability of the Savage-Hutter theory for computing inundation areas of granular flows. The stopping criterion is a function of dimensionless average velocity, pile aspect ratio and internal and bed friction angle and can be implemented on either a global (entire flow) or local (small areas of the flow) level. Slumping piles on a horizontal surface, and geophysical flows over complex topography were simulated. Mountainous areas, such as Colima volcano, Mexico; Casita, Nicaragua; Little Tahoma Peak, USA, and the San Bernardino Mountains, USA, were used as test regions. These areas have combinations of steep, open slopes and sinuous channels. Because of differences in topography and physical scaling, slumping piles in the laboratory and geophysical flows in natural terrain must be scaled differently to determine a reasonable dimensionless relationship for the stopping criterion.     

Infrared imagery of ‘breaking’ internal waves

Airborne infrared imagery is shown to provide preliminary evidence of surface thermal expressions associated with internal waves that become unstable and break over the continental shelf. These expressions include a narrow wave front that is warmer than the ambient; a wide, spatially intermittent ‘wake’ that is colder than the ambient; and ∼O (10 m) diameter surface-renewal ‘boils’ that populate the wake. These thermal signatures might be useful in assessing the spatial distribution and structure of breaking internal waves.     

Local‐scale and watershed‐scale determinants of summertime urban stream temperatures

The influence of urbanization on the temperature of small streams is widely recognized, but these effects are confounded by the great natural variety of their contributing watersheds. To evaluate the relative importance of local‐scale and watershed‐scale factors on summer temperatures in urban streams, hundreds of near‐instantaneous temperature measurements throughout the central Puget Lowland, western Washington State, were collected during a single 2‐h period in August in each of the years 1998–2001. Stream temperatures ranged from 8.9 to 27.5 °C, averaging 15.4 °C. Pairwise correlation coefficients between stream temperature and four watershed variables (total watershed area and the watershed percentages of urban development, upstream lakes, and permeable glacial outwash soils as an indicator of groundwater exchange) were uniformly very low. Akaike's information criterion was applied to determine the best‐supported sets of watershed‐scale predictor variables for explaining the variability of stream temperatures. For the full four‐year dataset, the only well‐supported model was the global model (using all watershed variables); for the most voluminous single‐year (1999) data, Akaike's information criterion showed greatest support for per cent outwash (Akaike weight of 0.44), followed closely by per cent urban development + per cent outwash, per cent lake area only, and the global model. Upstream lakes resulted in downstream warming of up to 3 °C; variability in riparian shading imposed a similar temperature range. Watershed urbanization itself is not the most important determining factor for summer temperatures in this region; even the long‐recognized effects of riparian shading can be no more influential than those imposed by other local‐scale and watershed‐scale factors. Copyright © 2013 John Wiley & Sons, Ltd.     

New Editor-in-Chief Professor Degan SHU

正Professor Shu received his undergraduate training in Paleontology at Peking(Beijing)University in1964–1969,obtaining his Master's degree at Northwest University(Xi’an)and Ph.D.in China University of Geosciences(Beijing);he was Visiting Scholar at the Smithsonian Institution,Washington,D.C.,USA in 1988,Humboldt Research Fellow at University of Bonn in 1988–1989,at University of Wuerzburg,Germany in 1994–1995,and Visiting Scholar at Cambridge University,UK     

Book Reviews

Committee on Protection and Management of Pacific Northwest Anadromous Salmonids Upstream: Salmon and Society in the Pacific Northwest

Cook, Ian G; Doel, Marcus A. and Li, Rex (eds.) Fragmented Asia: Regional Integration and National Disintegration in Pacific Asia

Crush, Jonathan Power of Development

de Blij, H. J., and Muller, Peter O. Physical Geography of the Global Environment

Hayward, David J. International Trade and Regional Economies: The Impacts of European Integration on the United States

Kennedy, Michael The Global Positioning System and GIS: An Introduction

Lowe, Philip; Marsden, Terry and Whatmore, Sarah (eds) Regulating Agriculture

Marsden, Terry; Lowe, Philip and Whatmore, Sarah (eds) Labour and Locality: Uneven Development and the Rural Labour Process

Marsden, Terry; Lowe, Philip and Whatmore, Sarah (eds) Rural Restructuring: Global Processes and Their Responses

Whatmore, Sarah; Marsden, Terry and Lowe, Philip (eds) Gender and Rurality

Whatmore, Sarah; Marsden, Terry and Lowe, Philip (eds) Rural Enterprise: Shifting Perspectives on Small-Scale Production

Martopo, Sugeng and Mitchell, Bruce (eds) Bali: Balancing Environment, Economy and Culture

Ould-Mey, Mohameden Global Restructuring and Peripheral States: The Carrot and the Stick in Mauritania

Redclift, Michael and Benton, Ted (eds) Social Theory and the Global Environment

Thomas–Slayter, Barbara and Rocheleau, Dianne Gender, Environment, and Development in Kenya: A Grassroots Perspective

Wallach, Bret Losing Asia: Modernization and the Culture of Development

Wennberg, John E. Dartmouth Atlas of Health Care

Wilson, David and Huff, James O. (eds) Marginalized Places and Populations: A Structurationist Agenda