Shale weathering rates across a continental-scale climosequence

A transect of sites has been established in North America and England as part of the Critical Zone Exploration Network (CZEN) to investigate the rates of soil formation across a climate gradient. Sites reported here are all underlain by an organic-poor, iron-rich Silurian-age shale, providing a constant parent material lithology from which soil is forming. This climosequence includes relatively cold and wet sites in Wales, New York and Pennsylvania, with temperature increasing to the south in Virginia, Tennessee and Alabama. Puerto Rico provides a warm/wet end member for the transect, although this site does not lie on the same shale formation as the Appalachian Mountain sites. Geochemical, mineralogical, and cosmogenic isotope analyses are being completed similarly at all sites to allow direct comparisons and eventual modelling of the weathering processes. Preliminary results from Wales, Pennsylvania and Virginia show soils become more sodium-depleted and the depth to bedrock is significantly deeper at the wet/warm site in Virginia. The fraction of Na lost relative to parent material composition at each site varies linearly as a function of mean annual temperature. Overall, results from the transect will promote a better understanding of how climate changes and human activities impact soil formation rates

Shale weathering rates across a continental-scale climosequence

A transect of sites has been established in North America and England as part of the Critical Zone Exploration Network (CZEN) to investigate the rates of soil formation across a climate gradient. Sites reported here are all underlain by an organic-poor, iron-rich Silurian-age shale, providing a constant parent material lithology from which soil is forming. This climosequence includes relatively cold and wet sites in Wales, New York and Pennsylvania, with temperature increasing to the south in Virginia, Tennessee and Alabama. Puerto Rico provides a warm/wet end member for the transect, although this site does not lie on the same shale formation as the Appalachian Mountain sites. Geochemical, mineralogical, and cosmogenic isotope analyses are being completed similarly at all sites to allow direct comparisons and eventual modelling of the weathering processes. Preliminary results from Wales, Pennsylvania and Virginia show soils become more sodium-depleted and the depth to bedrock is significantly deeper at the wet/warm site in Virginia. The fraction of Na lost relative to parent material composition at each site varies linearly as a function of mean annual temperature. Overall, results from the transect will promote a better understanding of how climate changes and human activities impact soil formation rates

Quantifying Exceptionally Large Populations of \u3ci\u3eAcropora\u3c/i\u3e spp. Corals Off Belize Using Sub-Meter Satellite Imagery Classification

Caribbean coral reefs have experienced dramatic declines in live coral cover in recent decades. Primary branching framework Caribbean corals, Acropora cervicornis (Lamarck, 1816) and Acropora palmata (Lamarck, 1816), have suffered the greatest collapse. Coral Gardens, Belize, is one of few remaining, and perhaps the largest, refugia for abundant, healthy, but undocumented populations of both Acropora species in the Caribbean Sea. In the present study, GeoEye-1 multispectral satellite imagery of a 25 km2 reefal area near Ambergris Caye, Belize, was analyzed to identify live Acropora spp. cover. We used a supervised classification to predict occurrence of areas with live Acropora spp. and to separate them from other benthic cover types, such as sandy bottom, seagrass, and mixed massive coral species. We tested classification accuracy in the field, and new Acropora spp. patches were mapped using differential GPS. Of 11 predicted new areas of Acropora spp., eight were composed of healthy Acropora spp. An unsupervised classification of a red (Band 3):blue (Band 1) ratio calculation of the image successfully separated Acropora corals from other benthic cover, with an overall accuracy of 90%. Our study identified 7.58 ha of reef dominated by Acropora spp. at Coral Gardens, which is one of the largest populations in the Caribbean Sea. We suggest that Coral Gardens may be an important site for the study of modern Acropora spp. resilience. Our technique can be used as an efficient tool for genera-specific identification, monitoring, and conservation of populations of endangered Acropora spp

Deglaciation of Fennoscandia

To provide a new reconstruction of the deglaciation of the Fennoscandian Ice Sheet, in the form of calendar-year time-slices, which are particularly useful for ice sheet modelling, we have compiled and synthesized published geomorphological data for eskers, ice-marginal formations, lineations, marginal meltwater channels, striae, ice-dammed lakes, and geochronological data from radiocarbon, varve, optically-stimulated luminescence, and cosmogenic nuclide dating. This 25 is summarized as a deglaciation map of the Fennoscandian Ice Sheet with isochrons marking every 1000 years between 22 and 13 cal kyr BP and every hundred years between 11.6 and final ice decay after 9.7 cal kyr BP. Deglaciation patterns vary across the Fennoscandian Ice Sheet domain, reflecting differences in climatic and geomorphic settings as well as ice sheet basal thermal conditions and terrestrial versus marine margins. For example, the ice sheet margin in the high-precipitation coastal setting of the western sector responded sensitively to climatic variations leaving a detailed record of prominent moraines and ice-marginal deposits in many fjords and coastal valleys. Retreat rates across the southern sector differed between slow retreat of the terrestrial margin in western and southern Sweden and rapid retreat of the calving ice margin in the Baltic Basin. Our reconstruction is consistent with much of the published research. However, the synthesis of a large amount of existing and new data support refined reconstructions in some areas. For example, we locate the LGM extent of the ice sheet in northwestern Russia further east than previously suggested and conclude that it occurred at a later time than the rest of the ice sheet, at around 17-15 cal kyr BP, and propose a slightly different chronology of moraine formation over southern Sweden based on improved correlations of moraine segments using new LiDAR data and tying the timing of moraine formation to Greenland ice core cold stages. Retreat rates vary by as much as an order of magnitude in different sectors of the ice sheet, with the lowest rates on the high-elevation and maritime Norwegian margin. Retreat rates compared to the climatic information provided by the Greenland ice core record show a general correspondence between retreat rate and climatic forcing, although a close match between retreat rate and climate is unlikely because of other controls, such as topography and marine versus terrestrial margins. Overall, the time slice reconstructions of Fennoscandian Ice Sheet deglaciation from 22 to 9.7 cal kyr BP provide an important dataset for understanding the contexts that underpin spatial and temporal patterns in retreat of the Fennoscandian Ice Sheet, and are an important resource for testing and refining ice sheet models

Glacier velocities and dynamic ice discharge from the Queen Elizabeth Islands, Nunavut, Canada

Recent studies indicate an increase in glacier mass loss from the Canadian Arctic Archipelago as a result of warmer summer air temperatures. However, no complete assessment of dynamic ice discharge from this region exists. We present the first complete surface velocity mapping of all ice masses in the Queen Elizabeth Islands and show that these ice masses discharged ~2.6 ± 0.8 Gt a−1 of ice to the oceans in winter 2012. Approximately 50% of the dynamic discharge was channeled through non surge-type Trinity and Wykeham Glaciers alone. Dynamic discharge of the surge-type Mittie Glacier varied from 0.90 ± 0.09 Gt a−1 during its 2003 surge to 0.02 ± 0.02 Gt a−1 during quiescence in 2012, highlighting the importance of surge-type glaciers for interannual variability in regional mass loss. Queen Elizabeth Islands glaciers currently account for ~7.5% of reported dynamic discharge from Arctic ice masses outside Greenland.We thank NSERC, Canada Foundation for Innovation, Ontario Research Fund, ArcticNet, Ontario Graduate Scholarship, University of Ottawa and the NSERC Canada Graduate Scholarship for funding. RADARSAT-2 data were provided by MacDonald, Dettwiler and Associates under the RADARSAT-2 Government Data Allocation administrated by the Canadian Space Agency. Support to DB is provided through the Climate Change Geosciences Program, Earth Sciences Sector, Natural Resources Canada (ESS Contribution #20130293). We also acknowledge support from U.K NERC for grants R3/12469 and NE/K004999 to JAD.This is the accepted version of an article published in Geophysical Research Letters. An edited version of this paper was published by AGU. Copyright (2014) American Geophysical Union. The final version is available at http://onlinelibrary.wiley.com/doi/10.1002/2013GL058558/abstract;jsessionid=6A3AD907C4383DA5D4E20C4924D6EC18.f02t02

Environmental and Molecular Mutagenesis Meeting Report Assessing Human Germ-Cell Mutagenesis in the Post-Genome Era: A Celebration of the Legacy of William Lawson (Bill) Russell

ABSTRACT Although numerous germ-cell mutagens have been identified in animal model systems, to date, no human germ-cell mutagens have been confirmed. Because the genomic integrity of our germ cells is essential for the continuation of the human species, a resolution of this enduring conundrum is needed. To facilitate such a resolution, we organized a workshop at The Jackson Laboratory in Bar Harbor, Maine on September [28][29][30] 2004. This interactive workshop brought together scientists from a wide range of disciplines to assess the applicability of emerging molecular methods for genomic analysis to the field of human germ-cell mutagenesis. Participants recommended that focused, coordinated human germ-cell mutation studies be conducted in relation to important societal exposures. Because cancer survivors represent a unique cohort with well-defined exposures, there was a consensus that studies should be designed to assess the mutational impact on children born to parents who had received certain types of mutagenic cancer chemotherapy prior to conceiving their children. Within this high-risk cohort, parents and children could be evaluated for inherited changes in (a) gene sequences and chromosomal structure, (b) repeat sequences and minisatellite regions, and (c) global gene expression and chromatin. Participants also recommended studies to examine trans-generational effects in humans involving mechanisms such as changes in imprinting and methylation patterns, expansion of nucleotide repeats, or induction of mitochondrial DNA mutations. Workshop participants advocated establishment of a bio-bank of human tissue samples that could be used to conduct a multiple-endpoint, comprehensive, and collaborative effort to detect exposure-induced heritable alterations in the human genome. Appropriate animal models of human germ-cell mutagenesis should be used in parallel with human studies to provide insights into the mechanisms of mammalian germ-cell mutagenesis. Finally, participants recommended that 4 scientific specialty groups be convened to address specific questions regarding the potential germ-cell mutagenicity of environmental, occupational, and lifestyle exposures. Strong support from relevant funding agencies and engagement of scientists outside the fields of genomics and germ-cell mutagenesis will be required to launch a full-scale assault on some of the most pressing and enduring questions in environmental mutagenesis: Do human germ-cell mutagens exist, what risk do they pose to future generations, and are some parents at higher risk than others for acquiring and transmitting germ-cell mutations?

Geologic Analyses for Evaluating Watershed Heterogeneity: Implications for Otolith Chemistry Studies

Abstract: Studies using otolith chemistry to distinguish fish stocks in fresh waters have suggested that spatial heterogeneity in basin geology determines the scale of stock discrimination possible with this approach. However, no studies have illustrated an association between spatial variation in fish otolith chemistry and watershed geology. We consider this relationship in the context of a recent study describing within-and between-river variation in trace element chemistry of otoliths from YOY smallmouth bass (Micropterus dolomieu) from the Maury and James rivers (Virginia). Cluster analysis of multivariate geologic data for discrete river segment basins illustrates a phenomenological association between geologic heterogeneity and our ability to discriminate spatial groupings of fish from their otolith chemistry. This analysis provides two significant results: 1) a starting point for considering the mechanistic relationship between watershed geology and fish otolith chemistry; and, 2) a framework for assessing basin heterogeneity prior to designing studies that use otolith chemistry to distinguish fish stocks in river-tributary networks. The latter can be used a priori to determine the efficacy of otolith chemistry comparisons and to guide sample collection over large spatial areas. In approximately the last decade, significant advances were made in analysis of fish "hard parts" (e.g., bones, scales, and spines) as records of water chemistry in areas inhabited by fish during their lifetimes Our objective in this paper is to determine if differences in basin geology correspond with successful discrimination of fish origins in a recent study of otolith chemistry in riverine smallmouth bass (Micropterus dolomieu) populations. Trace element concentrations were used to successfully discriminate natal origins of age-0 smallmouth bass spawned in the James River or its tributary Maury River. The analysis was further able to differentiate among fish collected from different segments of the Maury River based on otolith chemistry. Here we compare the spatial resolution of fish origin discrimination in this previous study (summarized below for context) with patterns of land attribute variation across the study area as a first-order attempt to illustrate an association between otolith chemistry and basin geology. Using readily available spatial data analyzed in a GIS, we present a framework for characterizing geology of river segment basins and for quantifying dissimilarity among basins in the study area. We then use cluster analysis to group segment basins with similar geologic compositions, and compare results of clustering with our ability to distinguish fish origins among basins by otolith chemistry. We discuss our results in the context of applying these methods to guide experimental design and collection effort in future studies of otolith chemistry in river systems. Study Area and Otolith Chemistry Study The James River is a large (fifth order) river that runs from the Ridge and Valley physiographic province through the Coastal Plain. The Maury River is a smaller (fourth order) river that originates in the Ridge and Valley and terminates in the James River at the edge of the Blue Ridge province. The James River and its 13

Foreland Basin Record of Uplift and Exhumation of the Eastern Cordillera, Northwest Argentina

The style, tempo, and timing of orogenic plateaus such as the Altiplano-Puna in South America are actively debated. Foreland basin strata in northwestern Argentina preserve a record of the eastward propagation, uplift, and erosion of the eastern margin of the high topography of the Puna plateau and Eastern Cordillera. Herein, we present new sedimentologic and geochronologic data from the Neogene foreland basin strata and modern fluvial sediments at 23°S to reveal the timing of growth and erosion of the modern plateau margin. Traditional sedimentologic approaches, including conglomeratic clast counts and sandstone point-counts, combined with detrital zircon U-Pb age distributions preserve robust signatures that track changes in sediment provenance over the past 12 Ma. Growth of the modern plateau edge commenced between 12 and 7 Ma and erected a topographic barrier that cut off the supply of sediment from more westerly sources. Erosion of this rising block has progressively dissected a cover of early Paleozoic sediments of the Mesón and Santa Victoria Groups, leading to deep incision into the pre-Cambrian metasediments of the Puncoviscana Formation that continues today. Detrital apatite and zircon fission track data from the both the Neogene strata and modern streams document erosion of the frontal block at a rate of about 0.6 mm/a.Fil: Rahl, Jeffrey. Washington and Lee University; Estados UnidosFil: Harbor, David. Washington and Lee University; Estados UnidosFil: Galli, Claudia Inés. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: O'Sullivan, Paul. GeoSep Services; Estados Unido