1,157 research outputs found
Comparing Trace Elements (As, Cu, Ni, Pb, and Zn) in Soils and Surface Waters among Montane, Upland Watersheds and Lowland, Urban Watersheds in New England, USA
Trace element biogeochemistry from soils to rivers is important for toxicity to aquatic ecosystems. The objective of this study was to determine whether trace element exports in contrasting watersheds are controlled by their abundance in soil, current land uses in the watershed, or geologic processes. Upland soils and river water samples were collected throughout the Deerfield watershed in southern Vermont and western Massachusetts and in the Quinebaug and Shetucket watersheds of eastern Connecticut. Soil concentrations were only an important predictor for dissolved Fe export, but no other trace element. Soil pH was not correlated with normalized dissolved exports of trace elements, but DOC was correlated with normalized dissolved Pb and Ni exports. The limited spatial and depth of soil sampling may have contributed to the poor correlation. Surprisingly, linear regressions and principal component analysis showed that human development was associated with higher soil trace metal concentrations but not significantly correlated with dissolved trace elements export. Instead, forest abundance was a strong predictor for lower Cu, Pb, and Zn soil concentrations and lower As, Fe, Ni and Pb dissolved exports across the watersheds. Dissolved exports of Al, K, and Si suggest that enhanced mineral dissolution in the montane watersheds was likely an important factor for matching or exceeding normalized pollutant trace element exports in more urbanized watersheds. Further studies are needed to evaluate subsurface/hyporheic controls as well as soil–surface water interface to quantify exchange and transport
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Transfer of Macronutrients, Micronutrients, and Toxic Elements from Soil to Grapes to White Wines in Uncontaminated Vineyards
Wine is a popular beverage and may be a source of nutrient and toxic elements during human consumption. Here, we explored the variation in nutrient and toxic elements from soils to grape berries and commercial white wines (Chardonnay) at five USA vineyards (New York, Vermont, California, Virginia) with strongly contrasting geology, soils, and climates. Samples were analyzed for macronutrients (Ca, K, and Mg), micronutrients (Mn, Cu, and Zn), and toxic elements (As, Cd, and Pb). Our study showed contrasting macronutrient, micronutrient, and toxic element concentrations in soils and in vines, leaves, and grapes. However, plant tissue concentrations did not correspond with total soil concentrations, suggesting a disconnect governing their accumulation. Bioconcentration factors for soil to grape berry transfer suggest the accumulation of Ca, K and Mg in berries while Fe, Mn, Cu, Zn, and Pb were generally not accumulated in our study or in previous studies. Wines from the five vineyards studied had comparable nutrient, micronutrient, and toxic metal concentrations as wines from Germany, Italy, Portugal, Spain, Croatia, Czech Republic, and Japan. The transfer of nutrients and toxic elements from grape berries to wine indicated that only Ca, K, and Mg were added or retained while concentrations of all other micronutrients and toxic elements were somewhat to extensively diminished. Thus, there appears to be a substantial effect on the geochemistry of the wine from the grape from either the fermentation process (i.e., flocculation), or a dilution effect. We conclude that soils, geology, and climate do not appear to generate a unique geochemical terroir as the transfer and concentration of inorganic nutrients appear to be comparable across strongly contrasting vineyards. This has several implications for human health. Nutrients in wine have potential impacts for human nutrition, as wine can meet or exceed the recommended dietary requirements of Ca, K, Mg, and Fe, and toxic metals As and Pb concentrations were also non-trivial
Regolith Weathering and Sorption Influences Molybdenum, Vanadium, and Chromium Export via Stream Water at Four Granitoid Critical Zone Observatories
Understanding the fate of oxyanions in the Critical Zone is important because of their biological significance and the potential for their use as geochemical tracers in terrestrial environments and subsurface systems. This study assessed the partitioning and transport of a suite of oxyanion metals (Mo, V, and Cr) in regolith profiles and stream waters from four granitoid Critical Zone Observatories (CZOs) (Boulder Creek, Calhoun, Luquillo, and Southern Sierra). For regolith profiles, we compared Mo, V, and Cr in total digestions and two extractions targeting oxyanions adsorbed to organic matter and amorphous oxides (H2O2 + 0.1 M acetic acid) and secondary Fe oxides (citrate–bicarbonate–dithionite). Total Mo, V, and Cr ranged from 0.4 to 2.5 mg kg-1, 16 to 208 mg kg-1, and 0.2 to 55 mg kg-1, respectively. The greatest concentrations of the oxyanions did not occur in surface soil samples, nor deepest regolith samples (7–10 m in depth), but instead in subsurface peaks that corresponded with secondary Fe oxides and total organic carbon. The average organic and amorphous oxide bound phase was 0.1–3.5% while the secondary Fe oxide fraction was 4–27% of the respective total concentrations for oxyanions, suggesting that secondary Fe oxides were an important phase across the regolith profile. Stream water Mo, V, and Cr concentrations ranged from 0.02 to 0.25 μg L-1, 0.2 to 1.8 μg L-1, and 0.08 to 0.44 μg L-1, respectively. Our results demonstrate that the deep regolith (2–7 m in depth) play an active role in both sourcing and retention of oxyanions. In addition, we observed that increased weathering intensity at warmer, wetter climates does not always lead to increased depletion in regolith or stream water export, which implies the importance of transport processes within regolith. Further quantification of oxyanion export from regolith can aid in developing their use as geochemical tools for global weathering
Characterization of Singlet Ground and Low-Lying Electronic Excited States of Phosphaethyne and Isophosphaethyne
The singlet ground _X˜ 1_+_ and excited _1_− , 1__ states of HCP and HPC have been systematically investigated using ab initio molecular electronic structure theory. For the ground state, geometries of the two linear stationary points have been optimized and physical properties have been predicted utilizing restricted self-consistent field theory, coupled cluster theory with single and double excitations _CCSD_, CCSD with perturbative triple corrections _CCSD_T__, and CCSD with partial iterative triple excitations _CCSDT-3 and CC3_. Physical properties computed for the global minimum _X˜ 1_+HCP_ include harmonic vibrational frequencies with the cc-pV5Z CCSD_T_ method of _1=3344 cm−1, _2=689 cm−1, and _3=1298 cm−1. Linear HPC, a stationary point of Hessian index 2, is predicted to lie 75.2 kcal mol−1 above the global minimum HCP. The dissociation energy D0_HCP_X˜ 1_+_→H_2S_+CP_X 2_+__ of HCP is predicted to be 119.0 kcal mol−1, which is very close to the experimental lower limit of 119.1 kcal mol−1. Eight singlet excited states were examined and their physical properties were determined employing three equation-of-motion coupled cluster methods _EOM-CCSD, EOM-CCSDT-3, and EOM-CC3_. Four stationary points were located on the lowest-lying excited state potential energy surface, 1_− →1A_, with excitation energies Te of 101.4 kcal mol−1_1A_ HCP_, 104.6 kcal mol−1_1_− HCP_, 122.3 kcal mol−1_1A_ HPC_, and 171.6 kcal mol−1_1_− HPC_ at the cc-pVQZ EOM-CCSDT-3 level of theory. The physical properties of the 1A_ state with a predicted bond angle of 129.5° compare well with the experimentally reported first singlet state _A˜ 1A__. The excitation energy predicted for this excitation is T0=99.4 kcal mol−1_34 800 cm−1 , 4.31 eV_, in essentially perfect agreement with the experimental value of T0=99.3 kcal mol−1_34 746 cm−1 ,4.308 eV_. For the second lowest-lying excited singlet surface, 1_→1A_, four stationary points were found with Te values of 111.2 kcal mol−1 _21A_ HCP_, 112.4 kcal mol−1 _1_ HPC_, 125.6 kcal mol−1_2 1A_ HCP_, and 177.8 kcal mol−1_1_ HPC_. The predicted CP bond length and frequencies of the 2 1A_ state with a bond angle of 89.8° _1.707 Å, 666 and 979 cm−1_ compare reasonably well with those for the experimentally reported C ˜ 1A_ state _1.69 Å, 615 and 969 cm−1_. However, the excitation energy and bond angle do not agree well: theoretical values of 108.7 kcal mol−1 and 89.8° versus experimental values of 115.1 kcal mol−1 and 113°
Higher-Order Corrections to Instantons
The energy levels of the double-well potential receive, beyond perturbation
theory, contributions which are non-analytic in the coupling strength; these
are related to instanton effects. For example, the separation between the
energies of odd- and even-parity states is given at leading order by the
one-instanton contribution. However to determine the energies more accurately
multi-instanton configurations have also to be taken into account. We
investigate here the two-instanton contributions. First we calculate
analytically higher-order corrections to multi-instanton effects. We then
verify that the difference betweeen numerically determined energy eigenvalues,
and the generalized Borel sum of the perturbation series can be described to
very high accuracy by two-instanton contributions. We also calculate
higher-order corrections to the leading factorial growth of the perturbative
coefficients and show that these are consistent with analytic results for the
two-instanton effect and with exact data for the first 200 perturbative
coefficients.Comment: 7 pages, LaTe
Spatial and vertical distribution of mercury in upland forest soils across the northeastern United States
Assessing current Hg pools in forest soils of the northeastern U.S. is important for monitoring changes in Hg cycling. The forest floor, upper and lower mineral horizons were sampled at 17 long-term upland forest sites across the northeastern U.S. in 2011. Forest floor Hg concentration was similar across the study region (274 +/- 13 mu g kg(-1)) while Hg amount at northern sites (39 +/- g ha(-1)) was significantly greater than at western sites (11 +/- 4 g ha(-1)). Forest floor Hg was correlated with soil organic matter, soil pH, latitude and mean annual precipitation and these variables explained approximately 70% of the variability when multiple regressed. Mercury concentration and amount in the lower mineral soil was correlated with Fe, soil organic matter and latitude, corresponding with Bs horizons of Spodosols (Podzols). Our analysis shows the importance of regional and soil properties on Hg accumulation in forest soils. (C) 2013 Elsevier Ltd. All rights reserved
Sources, mechanisms, and timescales of sediment delivery to a New England salt marsh
© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Baranes, H., Woodruff, J., Geyer, W., Yellen, B., Richardson, J. & Griswold, F. Sources, mechanisms, and timescales of sediment delivery to a New England salt marsh. Journal of Geophysical Research: Earth Surface, 127, (2022): e2021JF006478, https://doi.org/10.1029/2021jf006478.he availability and delivery of an external clastic sediment source is a key factor in determining salt marsh resilience to future sea level rise. However, information on sources, mechanisms, and timescales of sediment delivery are lacking, particularly for wave-protected mesotidal estuaries. Here we show that marine sediment mobilized and delivered during coastal storms is a primary source to the North and South Rivers, a mesotidal bar-built estuary in a small river system impacted by frequent, moderate-intensity storms that is typical to New England (United States). On the marsh platform, deposition rates, clastic content, and dilution of fluvially-sourced contaminated sediment by marine material all increase down-estuary toward the inlet, consistent with a predominantly marine-derived sediment source. Marsh clastic deposition rates are also highest in the storm season. We observe that periods of elevated turbidity in channels and over the marsh are concurrent with storm surge and high wave activity offshore, rather than with high river discharge. Flood tide turbidity also exceeds ebb tide turbidity during storm events. Timescales of storm-driven marine sediment delivery range from 2.5 days to 2 weeks, depending on location within the estuary; therefore the phasing of storm surge and waves with the spring-neap cycle determines how effectively post-event suspended sediment is delivered to the marsh platform. This study reveals that sediment supply and the associated resilience of New England mesotidal salt marshes involves the interplay of coastal and estuarine processes, underscoring the importance of looking both up- and downstream to identify key drivers of environmental change.The project described in this publication was in part supported by Grant or Cooperative Agreement No. G20AC00071 from the U.S. Geological Survey and a Department of Interior Northeast Climate Adaptation Science Center graduate fellowship awarded to H.E.B (G12AC00001)
Widespread Translocation from Autosomes to Sex Chromosomes Preserves Genetic Variability in an Endangered Lark
Species that pass repeatedly through narrow population bottlenecks (<100 individuals) are likely to have lost a large proportion of their genetic variation. Having genotyped 92 Raso larks Alauda razae, a Critically Endangered single-island endemic whose world population in the Cape Verdes over the last 100Â years has fluctuated between about 15 and 130 pairs, we found variation at 7 of 21 microsatellite loci that successfully amplified, the remaining loci being monomorphic. At 6 of the polymorphic loci variation was sex-linked, despite the fact that these microsatellites were not sex-linked in the other passerine birds where they were developed. Comparative analysis strongly suggests that material from several different autosomes has been recently transferred to the sex chromosomes in larks. Sex-linkage might plausibly allow some level of heterozygosity to be maintained, even in the face of persistently small population sizes
Applications of Field-Theoretic Renormalization Group Methods to Reaction-Diffusion Problems
We review the application of field-theoretic renormalization group (RG)
methods to the study of fluctuations in reaction-diffusion problems. We first
investigate the physical origin of universality in these systems, before
comparing RG methods to other available analytic techniques, including exact
solutions and Smoluchowski-type approximations. Starting from the microscopic
reaction-diffusion master equation, we then pedagogically detail the mapping to
a field theory for the single-species reaction k A -> l A (l < k). We employ
this particularly simple but non-trivial system to introduce the
field-theoretic RG tools, including the diagrammatic perturbation expansion,
renormalization, and Callan-Symanzik RG flow equation. We demonstrate how these
techniques permit the calculation of universal quantities such as density decay
exponents and amplitudes via perturbative eps = d_c - d expansions with respect
to the upper critical dimension d_c. With these basics established, we then
provide an overview of more sophisticated applications to multiple species
reactions, disorder effects, L'evy flights, persistence problems, and the
influence of spatial boundaries. We also analyze field-theoretic approaches to
nonequilibrium phase transitions separating active from absorbing states. We
focus particularly on the generic directed percolation universality class, as
well as on the most prominent exception to this class: even-offspring branching
and annihilating random walks. Finally, we summarize the state of the field and
present our perspective on outstanding problems for the future.Comment: 10 figures include
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Tools for monitoring and study of peregrine pheretimoid earthworms (Megascolecidae)
Peregrine pheretimoid earthworms, commonly known as jumping worms, are members of the family Megascolecidae that have become widely established outside of their native ranges. In many parts of the world this represents a second wave of earthworm invasions, following the introduction of peregrine European earthworms in the family Lumbricidae during the colonial era. Forest ecologists, turf managers, gardeners, and other land managers are concerned about the observed or presumed negative effects of jumping worms on invaded habitats. Although research on jumping worms has accelerated in recent decades, our understanding of their ecology remains limited. We compiled techniques useful to researchers working to fill voids in our understanding. Similar past efforts have focused on tools used to study common European species. Differences in life cycle, behavior, morphology, and physiology make it difficult to transfer experiences with European earthworms to pheretimoids. For example, the loss of reproductive features in many pheretimoid populations poses a challenge for identification, and techniques for individually tagging lumbricid earthworms have been less successful for megascolecids. The active and ongoing expansion of pheretimoid populations in many areas requires increased attention on distributed methods, such as citizen-science protocols, for detecting and tracking their expansion. Finally, the desire to limit populations of pheretimoids, including those invading gardens and other environments that might be successfully restored, has exposed the lack of options for targeted, effective control of unwanted earthworms. We identify opportunities to address these voids in our methodological tool kit and encourage the adaptation of techniques previously used in the study and management of other invasive animals
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