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Talkin' guitar : a story of young Doc Watson
\"With lyrical text and ... illustrations, Robbin Gourley tells the story of a boy whose spirit and determination led him to become one of the most celebrated and beloved figures of folk, bluegrass, and old-time music\"--Dust jacket flap.
Book
Landscape controls on riverine export of dissolved organic carbon from Great Britain
The dissolved organic carbon (DOC) export from land to ocean via rivers is a significant term in the global C cycle, and has been modified in many areas by human activity. DOC exports from large global rivers are fairly well quantified, but those from smaller river systems, including those draining oceanic regions, are generally under-represented in global syntheses. Given that these regions typically have high runoff and high peat cover, they may exert a disproportionate influence on the global land–ocean DOC export. Here we describe a comprehensive new assessment of the annual riverine DOC export to estuaries across the island of Great Britain (GB), which spans the latitude range 50–60° N with strong spatial gradients of topography, soils, rainfall, land use and population density. DOC yields (export per unit area) were positively related to and best predicted by rainfall, peat extent and forest cover, but relatively insensitive to population density or agricultural development. Based on an empirical relationship with land use and rainfall we estimate that the DOC export from the GB land area to the freshwater-seawater interface was 1.15 Tg C year−1 in 2017. The average yield for GB rivers is 5.04 g C m−2 year−1, higher than most of the world’s major rivers, including those of the humid tropics and Arctic, supporting the conclusion that under-representation of smaller river systems draining peat-rich areas could lead to under-estimation of the global land–ocean DOC export. The main anthropogenic factor influencing the spatial distribution of GB DOC exports appears to be upland conifer plantation forestry, which is estimated to have raised the overall DOC export by 0.168 Tg C year−1. This is equivalent to 15% of the estimated current rate of net CO2 uptake by British forests. With the UK and many other countries seeking to expand plantation forest cover for climate change mitigation, this ‘leak in the ecosystem’ should be incorporated in future assessments of the CO2 sequestration potential of forest planting strategies.
Journal Article
Stable Isotopic (δ13C) Evidence for Global Microbial Sequestration of Refractory Dissolved Organic Matter
Dissolved organic carbon (DOC) in the global oceans is an important long‐term carbon sink. Connections between molecular size, reactivity, and isotopic characteristics show that DOC exists on a continuum from biologically reactive to recalcitrant. The driving mechanisms behind the creation and persistence of recalcitrant DOC remain unknown. We show mean recalcitrant DOC (isolated via solid‐phase extraction; SPE‐DOC) δ13C values are 1.3 ± 0.6‰ lower than mean total DOC δ13C between depth ranges 0–200 m and 2–4 km on three GO‐SHIP Repeat Hydrography cruises. Lowest observed δ13C values correlate with low ∆14C and proximity to deep ocean hydrothermal systems. These data support the hypothesis that reworking of DOC through the microbial carbon pump is a key driver of the ocean's long‐term carbon sink. Mass‐balance modeling shows deep‐ocean DOC not captured by SPE is enriched in 13C, highlighting the need for continued research on non‐retained DOC to predict mechanisms that drive ocean carbon storage. Plain Language Summary The global oceans play an important role in Earth's climate, and dissolved organic carbon (DOC) (produced by surface ocean photosynthesis) has been recognized as a potential long‐term carbon sink in the deep ocean. However, the mechanisms behind the long‐term sink remain unknown. Recent research has shown that a phenomenon called the microbial carbon pump (MCP) may be a driving force in the production of long‐lasting “recalcitrant” DOC via heterotrophic consumption of nitrogen and phosphorus rich biomolecules and subsequent production of recalcitrant DOC as by‐product. The work presented here shows that this phenomenon, previously recognized on regional scales, may be systematic across the global oceans, indicated by our measurements in the Pacific, Indian, and Southern Oceans. Key Points Solid‐phase extracted dissolved organic carbon has low isotope signatures relative to bulk dissolved organic carbon in three ocean basins This research supports the hypothesis that bacteria drive the storage of recalcitrant organic matter through successive reworking Isotope measurements show hydrothermal vent influence likely captured in deep‐ocean solid‐phase extracted dissolved organic carbon
Journal Article
One deadly eye
\"A Russian diplomat disappears while Doc is tagging great white sharks in South Africa, and members of a criminal brotherhood, Bratva, don't think it's a coincidence. They track the biologist to Dinkin's Bay Marina on the west coast of Florida, where Brotherhood mercenaries have already deployed, prepared to pillage and kill in the wake of an approaching hurricane. No one, however, is prepared for a cataclysmic event that will forever change the island and leaves Doc to deal with escapees from Russia's most dangerous prison, including a serial killer--the Vulture Monk--who has a taste for blood. His only ally is an enigmatic British inventor whose decision to ride out the storm might have more to do with revenge than protecting a priceless art collection. Doc has a lot at stake--the lives of his fiancée, Hannah Smith, and their son, plus the fate of his hipster pal, Tomlinson, whose sailboat has disappeared in the Gulf of Mexico. The greatest threat of all, though, is a force that cannot be escaped--a Category Five hurricane that, minute by minute, melds sins of the past with Florida's precarious future\"-- Provided by publisher.
Book
Organizing Professionals
Amidst unprecedented levels of union organizing in higher education, Gary Rhoades combines the perspectives of a scholar and labor movement activist and leader to provide a comprehensive analysis of organizing campaigns and collective bargaining agreements for faculty (contingent and tenure-track), graduate students, and postdoc employees. Academic employees are organizing and negotiating for respect for workers, their work, and the public value of higher education. Rhoades analyzes how academic employees are shifting the imbalance of power between labor and management, reducing the internal professional stratification between segments of the academic workforce, and intersecting workplace issues with broader issues of equality, public value, and social justice, and in the process organizing and negotiating for a new, more progressive academy.
eBook
Modeling Allochthonous Dissolved Organic Carbon Mineralization Under Variable Hydrologic Regimes in Boreal Lakes
Here, we explore the interaction between hydrology and the reactivity of allochthonous dissolved organic carbon (DOCalloch) in determining the potential of DOCalloch to generate CO 2 through biological and photo-chemical mineralization in boreal lakes. We developed a mechanistic model that integrates the reactivity continuum (RC) concept to reconstruct in-lake mineralization of DOCalloch under variable hydrologic conditions using empirical measurements of DOCalloch concentrations and reactivity as model inputs. The model predicts lake DOCalloch concentration (L-DOCalloch) and its average overall reactivity ðKalloch Þ, which integrates the distribution of DOC alloch ages within the lake as a function of the DOC loading (DOCin), the initial reactivity of this DOCin (k₀), and the lake water residence time (WRT). The modeled DOCalloch mineralization rates and concentrations were in agreement with expectations based on observed and published values of ambient lake DOC concentrations and reactivity. Results from this modeling exercise reveal that the interaction between WRT and k₀ is a key determinant of the ambient concentration and reactivity of lake DOCalloch, which represents the bulk of DOC in most of these lakes. The steadystate (K̅alloch) also represents the proportion of CO₂ that can be extracted from DOCalloch during its transit through lakes, and partly explains the patterns in surface water pCO₂ oversaturation that have been observed across gradients of lake size and volume. We estimate that in-lake DOCalloch mineralization could potentially contribute on average 30–40% of the observed surface carbon dioxide partial pressure (pCO₂) across northern lakes. Applying the RC framework to in-lake DOCalloch dynamics improves our understanding of DOCalloch transformation and fate along the aquatic network, and results in a predictable mosaic of DOC reactivity and potential CO₂ emissions across lakes within a landscape.
Journal Article
Biological lability of terrestrial DOM increases CO₂ outgassing across Arctic shelves
Arctic shelf seas receive greater quantities of river runoff than any other ocean region and are experiencing increased freshwater loads and associated terrestrial matter inputs since recent decades. Amplified terrestrial permafrost thaw and coastal erosion is exposing previously frozen organic matter, enhancing its mobilization and release to nearshore regions. Changing terrestrial dissolved organic matter (terr-DOM) loads and composition may alter shelf primary productivity and respiration, ultimately affecting net regional CO₂ air–sea fluxes. However, the future evolution of Arctic Ocean climate feedbacks are highly dependent upon the biological degradability of terr-DOM in coastal waters, a factor often omitted in modelling studies. Here, we assess the sensitivity of CO₂ air–sea fluxes from East Siberian Arctic Shelf (ESAS) waters to changing terr-DOM supply and degradability using a biogeochemical model explicitly accounting for bacteria dynamics and shifting terr-DOM composition. We find increasing terr-DOM loads and degradability trigger a series of biogeochemical and ecological processes shifting ESAS waters from a net sink to a net source of CO₂, even after accounting for strengthening coastal productivity by additional land-derived nutrients. Our results suggest that future projected inputs of labile terr-DOM from peat and permafrost thaw may strongly increase the CO₂ efflux from the Arctic shelf sea, causing currently unquantified positive feedback to climate change.
Journal Article
Long-term sediment organic carbon remineralization in different seagrass and macroalgae habitats: implication for blue carbon storage
Seagrass and macroalgae beds are key blue carbon ecosystems in the ocean. However, coastal development and climate change are sparking a growing concern about the vulnerability of sediment organic carbon (OC) to remineralization after macrophyte perturbation. Thus, the aim of this study was to assess the potential of long-term remineralization of sediment OC stocks (1 year) in coastal vegetated habitats (i.e., seagrasses Zostera noltei and Cymodocea nodosa, macroalgae Caulerpa prolifera and unvegetated sediment) after complete disturbance of macrophyte meadows under conducive conditions to microorganisms growth (i.e., oxygen saturated, non-nutrient limitation, turbulence and dark). Leached dissolved organic carbon (DOC) from particulate organic carbon (POC) remineralization, carbonate dissolution and photo-reactivity of long-term persistent DOC were also evaluated. Our results evidenced that, sediment OC from Z. noltei and unvegetated habitats were entirely remineralized to CO2. However, sediment OC from C. nodosa and C. prolifera communities exhibited a significant fraction of recalcitrant OC, and therefore, a 42 and 46% of the sediment OC still remained after 1 year of culture, respectively. POC remineralization released relevant amounts of both labile and recalcitrant DOC, which showed low photo-reactivity. Finally, we discuss that the main argument to promote management, monitoring, and restoration programs for macrophytes is usually based on their sediment OC deposit, which favor larger species. The study presented here adds arguments to also include small macrophyte species, since their sediment OC may be highly labile and entirely remineralized to CO2 once these habitats are disturbed.
Journal Article
Review of Vehicle Engine Efficiency and Emissions
This review article summarizes major and representative developments in vehicle emissions regulations, engine efficiency, and emission control from 2017. The article starts with the key regulatory developments in the field, including newly proposed European light-duty (LD) CO₂ regulations (15 and 30% cuts in 2025 and 2030, respectively, from 2020 levels) and technical improvements of the Euro 6 real driving emissions (RDE) regulations. China finalized their new energy vehicle (NEV) mandates for 2019 and 2020. LD and heavy-duty (HD) engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging criteria and greenhouse gas (GHG) regulations. Several LD gasoline concepts are achieving 10-15% and some up to 35% reductions relative to gasoline direct injection (GDI) engines of today. Projections indicate tight CO₂ regulations will require some degree of hybridization and/or high-performing gasoline and diesel engines. Scoping work on HD engines is reported on achieving 55% break thermal efficiency (BTE) using methods that can reasonably be commercialized. Lean NOx control technologies are summarized, including selective catalytic reduction (SCR), NOx adsorbers, and systems. Fundamentals of the SCR reaction are explored at the atomistic level. Diesel particulate filter (DPF) work has been focused on structure-performance relationships and ash behavior. Research oxidation catalysts are approaching 90% efficiency for hydrocarbon (HC) and CO oxidation at 160-190 °C. Gasoline particulates are a major topic in emission control. The article provides a broad overview of various factors that can impact emissions. The impact of fuel composition and application is summarized. Gasoline particulate filter (GPF) durability and ash loading are better understood. Finally, the article discusses some key developments in three-way catalysts, with improved understanding of low-temperature performance. Advances in lean-burn gasoline emission control from a few labs are also summarized.
Journal Article