Multiscale divergence between Landsat- and lidar-based biomass mapping is related to regional variation in canopy cover and composition     

David M. Bell  Matthew J. Gregory  Van Kane  Jonathan Kane  Robert E. Kennedy  Heather M. Roberts  Zhiqiang Yang 《Carbon balance and management》2018,13(1):15

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Phosphorus and iron cycling in deep saprolite,Luquillo Mountains,Puerto Rico     

Heather L. Buss  Ryan Mathur  Arthur F. White  Susan L. Brantley 《Chemical Geology》2010,269(1-2):52-61

Rapid weathering and erosion rates in mountainous tropical watersheds lead to highly variable soil and saprolite thicknesses which in turn impact nutrient fluxes and biological populations. In the Luquillo Mountains of Puerto Rico, a 5-m thick saprolite contains high microorganism densities at the surface and at depth overlying bedrock. We test the hypotheses that the organisms at depth are limited by the availability of two nutrients, P and Fe. Many tropical soils are P-limited, rather than N-limited, and dissolution of apatite is the dominant source of P. We document patterns of apatite weathering and of bioavailable Fe derived from the weathering of primary minerals hornblende and biotite in cores augered to 7.5 m on a ridgetop as compared to spheroidally weathering bedrock sampled in a nearby roadcut.Iron isotopic compositions of 0.5 N HCl extracts of soil and saprolite range from about δ⁵⁶Fe = 0 to ? 0.1‰ throughout the saprolite except at the surface and at 5 m depth where δ⁵⁶Fe = ? 0.26 to ? 0.64‰. The enrichment of light isotopes in HCl-extractable Fe in the soil and at the saprolite–bedrock interface is consistent with active Fe cycling and consistent with the locations of high cell densities and Fe(II)-oxidizing bacteria, identified previously. To evaluate the potential P-limitation of Fe-cycling bacteria in the profile, solid-state concentrations of P were measured as a function of depth in the soil, saprolite, and weathering bedrock. Weathering apatite crystals were examined in thin sections and an apatite dissolution rate of 6.8 × 10^? 14 mol m^? 2 s^? 1 was calculated. While surface communities depend on recycled nutrients and atmospheric inputs, deep communities survive primarily on nutrients released by the weathering bedrock and thus are tightly coupled to processes related to saprolite formation including mineral weathering. While low available P may limit microbial activity within the middle saprolite, fluxes of P from apatite weathering should be sufficient to support robust growth of microorganisms in the deep saprolite.  相似文献   

The use of passive treatment alternatives for the mitigation of acidic drainage at the Williams Brother mine,California: Bench-scale study     

Erin J. Clyde  Pascale Champagne  Heather E. Jamieson 《Applied Geochemistry》2010

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James Stanley Hey, 1909–2000     

Nigel Henbest  Heather Couper 《Astronomy& Geophysics》2000,41(3):3.38-3.38

Fellow and Eddington Medallist of the RAS, Fellow of the Royal Society, MBE,pioneer in radar and radio astromy.
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Rethinking Poisson-Based Statistics for Ground Water Quality Monitoring     

Jim C. Loftis  Hariharan K. Iyer  Heather J. Baker 《Ground water》1999,37(2):275-281

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Developing underutilized fisheries: Oregon's developmental fisheries program     

Michael Harte  Polly Endreny  Gil Sylvia  Heather Munro Mann 《Marine Policy》2008,32(4):643-652

Oregon's Developmental Fisheries Program is designed to encourage the commercial exploration and development of State managed underutilized fishery resources. A key program strategy is allocating relatively secure harvest rights to pioneering entrepreneurs when a fishery successfully transitions from “developing” to “developed” status. Since the program's inception in 1993, two fisheries, sardine and bay clam, have moved from undeveloped to developed status. Case studies of these fisheries show that many challenges impact the success of the Developmental Fisheries Program including difficulties in designing and allocating asset rights, establishing operational program guidelines, selecting measurable targets that meet legislative standards for a developed fishery, and financing developmental fisheries management practices. Developmental fisheries strategies used in other regions and countries are summarized. Recommendations are made for improving Oregon's Developmental Fishery Program including establishing clear objectives and timelines for the Program and identifying appropriate renewal requirements for permits and other developmental incentives on a fishery-by-fishery basis.  相似文献   

The effects of disproportional load contributions on quantifying vegetated filter strip sediment trapping efficiencies     

Heather?E.?GallEmail authorView author&#;s OrcID profile  Daniel?Schultz  Tamie L.?Veith  Sarah C.?Goslee  Alfonso?Mejia  Ciaran J.?Harman  Cibin?Raj  Paul?H.?Patterson 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(8):2369-2380

Vegetated filter strips (VFSs) are a best management practice (BMP) commonly implemented adjacent to row-cropped fields to trap overland transport of sediment and other constituents present in agricultural runoff. Although they have been widely adopted, insufficient data exist to understand their short and long-term effectiveness. High inter-event variability in performance has been observed, yet the majority of studies report average removal efficiencies over observed or simulated events, ignoring the disproportional effects of loads into and out of VFSs over longer periods of time. We argue that due to positively correlated sediment concentration-discharge relationships, disproportional contribution of runoff events transporting sediment over the course of a year (i.e., temporal inequality), decreased performance with increasing flow rates, and effects of antecedent moisture condition, VFS removal efficiencies over annual time scales may be significantly lower than reported per-event averages. By applying a stochastic approach, we investigated the extent of disparity between reporting average efficiencies from each runoff event over the course of 1 year versus the total annual load reduction. Additionally, we examined the effects of soil texture, concentration-discharge relationship, and VFS slope in contributing to this disparity, with the goal of revealing potential errors that may be incurred by ignoring the effects of temporal inequality in quantifying VFS performance. Simulation results suggest that ignoring temporal inequality can lead to overestimation of annual performance by as little as < 2% and to as much as > 20%, with the greatest disparities observed for soils with high clay content.  相似文献   

Weighted residual method for diffraction of plane P-waves in a 2-D elastic half-space Ⅲ: on an almost circular arbitrary-shaped alluvial valley          下载免费PDF全文

Heather P.Brandow  Vincent Lee 《地震科学（英文版）》2018,(1)

Scattering and diffraction of elastic in-plane P-and SV-waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and strong motion seismologists for over forty years. The case of out-ofplane SH-waves on the same elastic canyon that is semicircular in shape on the half-space surface is the first such problem that was solved by analytic closed-form solutions over forty years ago by Trifunac. The corresponding case of in-plane P-and SV-waves on the same circular canyon is a much more complicated problem because the in-plane P-and SV-scattered waves have different wave speeds and together they must have zero normal and shear stresses at the half-space surface. It is not until recently in 2014 that analytic solution for such problem is found by Lee and Liu. This paper uses their technique of defining these stress-free scattered waves, which Brandow and Lee previously used to solve the problem of the scattering and diffraction of these in-plane waves on an almost-circular surface canyon that is arbitrary in shape, to the study of the scattering and diffraction of these in-plane waves on an almost circular arbitrary-shaped alluvial valley.  相似文献   

Scattering and diffraction of plane P-waves in a 2-D elastic half-space Ⅱ:shallow arbitrary shaped canyon     

Heather P. Brandow  Vincent Lee 《地震工程与工程振动(英文版)》2017,16(3):459-485

Scattering and Diffraction of elastic in-plane P- and SV- waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and strong-motion seismologists for over forty years. The case of out-of-plane SH waves on the same elastic canyon that is semi-circular in shape on the half-space surface is the first such problem that was solved by analytic closed form solutions over forty years ago by Trifunac. The corresponding case of in-plane P- and SV-waves on the same circular canyon is a much more complicated problem because, the in-plane P- and SV- scattered waves have different wave speeds and together they must have zero normal and shear stresses at the half-space surface. It is not until recently in 2014 that analytic solution for such problem is found by the author in the work of Lee and Liu. This paper uses the technique of Lee and Liu of defining these stress-free scattered waves to solve the problem of the scattered and diffraction of these in-plane waves on an almost-circular surface canyon that is arbitrary in shape.  相似文献   

Upward continuation of Dome-C airborne gravity and comparison with GOCE gradients at orbit altitude in east Antarctica     

Hasan Yildiz  Rene Forsberg  Carl Christian Tscherning  Daniel Steinhage  Graeme Eagles  Johannes Bouman 《Studia Geophysica et Geodaetica》2017,61(1):53-68

An airborne gravity campaign was carried out at the Dome-C survey area in East Antarctica between the 17th and 22nd of January 2013, in order to provide data for an experiment to validate GOCE satellite gravity gradients. After typical filtering for airborne gravity data, the cross-over error statistics for the few crossing points are 11.3 mGal root mean square (rms) error, corresponding to an rms line error of 8.0 mGal. This number is relatively large due to the rough flight conditions, short lines and field handling procedures used. Comparison of the airborne gravity data with GOCE RL4 spherical harmonic models confirmed the quality of the airborne data and that they contain more high-frequency signal than the global models. First, the airborne gravity data were upward continued to GOCE altitude to predict gravity gradients in the local North-East-Up reference frame. In this step, the least squares collocation using the ITGGRACE2010S field to degree and order 90 as reference field, which is subtracted from both the airborne gravity and GOCE gravity gradients, was applied. Then, the predicted gradients were rotated to the gradiometer reference frame using level 1 attitude quaternion data. The validation with the airborne gravity data was limited to the accurate gradient anomalies (T_XX, T_YY, T_ZZ and T_XZ) where the long-wavelength information of the GOCE gradients has been replaced with GOCO03s signal to avoid contamination with GOCE gradient errors at these wavelengths. The comparison shows standard deviations between the predicted and GOCE gradient anomalies T_XX, T_YY, T_ZZ and T_XZ of 9.9, 11.5, 11.6 and 10.4 mE, respectively. A more precise airborne gravity survey of the southern polar gap which is not observed by GOCE would thus provide gradient predictions at a better accuracy, complementing the GOCE coverage in this region.  相似文献