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Scott J Goetz Alessandro Baccini Nadine T Laporte Tracy Johns Wayne Walker Josef Kellndorfer Richard A Houghton Mindy Sun 《Carbon balance and management》2009,4(1):2-7
Mapping and monitoring carbon stocks in forested regions of the world, particularly the tropics, has attracted a great deal
of attention in recent years as deforestation and forest degradation account for up to 30% of anthropogenic carbon emissions,
and are now included in climate change negotiations. We review the potential for satellites to measure carbon stocks, specifically
aboveground biomass (AGB), and provide an overview of a range of approaches that have been developed and used to map AGB across
a diverse set of conditions and geographic areas. We provide a summary of types of remote sensing measurements relevant to
mapping AGB, and assess the relative merits and limitations of each. We then provide an overview of traditional techniques
of mapping AGB based on ascribing field measurements to vegetation or land cover type classes, and describe the merits and
limitations of those relative to recent data mining algorithms used in the context of an approach based on direct utilization
of remote sensing measurements, whether optical or lidar reflectance, or radar backscatter. We conclude that while satellite
remote sensing has often been discounted as inadequate for the task, attempts to map AGB without satellite imagery are insufficient.
Moreover, the direct remote sensing approach provided more coherent maps of AGB relative to traditional approaches. We demonstrate
this with a case study focused on continental Africa and discuss the work in the context of reducing uncertainty for carbon
monitoring and markets. 相似文献
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Tarang Khangaonkar Brandon Sackmann Wen Long Teizeen Mohamedali Mindy Roberts 《Ocean Dynamics》2012,62(9):1353-1379
Nutrient pollution from rivers, nonpoint source runoff, and nearly 100 wastewater discharges is a potential threat to the ecological health of Puget Sound with evidence of hypoxia in some basins. However, the relative contributions of loads entering Puget Sound from natural and anthropogenic sources, and the effects of exchange flow from the Pacific Ocean are not well understood. Development of a quantitative model of Puget Sound is thus presented to help improve our understanding of the annual biogeochemical cycles in this system using the unstructured grid Finite-Volume Coastal Ocean Model framework and the Integrated Compartment Model (CE-QUAL-ICM) water quality kinetics. Results based on 2006 data show that phytoplankton growth and die-off, succession between two species of algae, nutrient dynamics, and dissolved oxygen in Puget Sound are strongly tied to seasonal variation of temperature, solar radiation, and the annual exchange and flushing induced by upwelled Pacific Ocean waters. Concentrations in the mixed outflow surface layer occupying approximately 5–20?m of the upper water column show strong effects of eutrophication from natural and anthropogenic sources, spring and summer algae blooms, accompanied by depleted nutrients but high dissolved oxygen levels. The bottom layer reflects dissolved oxygen and nutrient concentrations of upwelled Pacific Ocean water modulated by mixing with biologically active surface outflow in the Strait of Juan de Fuca prior to entering Puget Sound over the Admiralty Inlet. The effect of reflux mixing at the Admiralty Inlet sill resulting in lower nutrient and higher dissolved oxygen levels in bottom waters of Puget Sound than the incoming upwelled Pacific Ocean water is reproduced. By late winter, with the reduction in algal activity, water column constituents of interest, were renewed and the system appeared to reset with cooler temperature, higher nutrient, and higher dissolved oxygen waters from the Pacific Ocean. 相似文献
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Chlo??E.?BonamiciEmail author William?S.?Kinman John?H.?Fournelle Mindy?M.?Zimmer Anthony?D.?Pollington Kirk?D.?Rector 《Contributions to Mineralogy and Petrology》2017,172(1):2
Glassy nuclear fallout debris from near-surface nuclear tests is fundamentally reprocessed earth material. A geochemical approach to analysis of glassy fallout is uniquely suited to determine the means of reprocessing and shed light on the mechanisms of fallout formation. An improved understanding of fallout formation is of interest both for its potential to guide post-detonation nuclear forensic investigations and in the context of possible affinities between glassy debris and other glasses generated by high-energy natural events, such as meteorite impacts and lightning strikes. This study presents a large major-element compositional dataset for glasses within aerodynamic fallout from the Trinity nuclear test (“trinitite”) and a geochemically based analysis of the glass compositional trends. Silica-rich and alkali-rich trinitite glasses show compositions and textures consistent with formation through melting of individual mineral grains—quartz and alkali feldspar, respectively—from the test-site sediment. The volumetrically dominant glass phase—called the CaMgFe glass—shows extreme major-element compositional variability. Compositional trends in the CaMgFe glass are most consistent with formation through volatility-controlled condensation from compositionally heterogeneous plasma. Radioactivity occurs only in CaMgFe glass, indicating that co-condensation of evaporated bulk ground material and trace device material was the main mechanism of radioisotope incorporation into trinitite. CaMgFe trinitite glasses overlap compositionally with basalts, rhyolites, fulgurites, tektites, and microtektites but display greater compositional diversity than all of these naturally formed glasses. Indeed, the most refractory CaMgFe glasses compositionally resemble early solar system condensates—specifically, CAIs. 相似文献
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Biological and Physical Attenuation of Endocrine Disruptors and Pharmaceuticals: Implications for Water Reuse 总被引：2，自引：0，他引：2
Shane A. Snyder Joseph Leising Paul Westerhoff Yeomin Yoon Heath Mash Brett Vanderford 《Ground Water Monitoring & Remediation》2004,24(2):108-118
A select group of endocrine disrupters, pharmaceuticals, and personal care products was studied to determine the degree of biological attenuation in water reuse applications. Laboratory investigations involved both batch reactors using biologically active sand and continuous flow simulated aquifer storage and recovery experiments. All laboratory experiments were conducted using Colorado River water spiked with various target compounds at concentrations between 10 and 100 ng/L. Field studies were also conducted to determine the occurrence and attenuation of target compounds in water reuse applications. Two golf courses irrigated with reuse water were studied to determine if turf applications led to contamination of nearby ground water. A waste water treatment facility that uses rapid infiltration basins seasonally was also tested to determine the degree of attenuation of detectable target compounds along a subsurface flowpath. A qualitative structural activity relationship model was applied to the target compounds to predict the general rate of aerobic biological degradation. Significant attenuation of many target compounds was observed in both laboratory and field experiments. Conversely, several compounds displayed limited removal during these studies. Field experiments were limited to detectable compounds and various nonbiological removal or concentration effects that may impact data interpretations, which are discussed in this paper. The predictive model was found to be moderately accurate within the confines of the project scope. 相似文献
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Tarang Khangaonkar Zhaoqing Yang Taeyun Kim Mindy Roberts 《Estuarine, Coastal and Shelf Science》2011
Through extensive field data collection and analysis efforts conducted since the 1950s, researchers have established an understanding of the characteristic features of circulation in Puget Sound. The pattern ranges from the classic fjordal behavior in some basins, with shallow brackish outflow and compensating inflow immediately below, to the typical two-layer flow observed in many partially mixed estuaries with saline inflow at depth. An attempt at reproducing this behavior by fitting an analytical formulation to past data is presented, followed by the application of a three-dimensional circulation and transport numerical model. The analytical treatment helped identify key physical processes and parameters, but quickly reconfirmed that response is complex and would require site-specific parameterization to include effects of sills and interconnected basins. The numerical model of Puget Sound, developed using unstructured-grid finite volume method, allowed resolution of the sub-basin geometric features, including presence of major islands, and site-specific strong advective vertical mixing created by bathymetry and multiple sills. The model was calibrated using available recent short-term oceanographic time series data sets from different parts of the Puget Sound basin. The results are compared against 1) recent velocity and salinity data collected in Puget Sound from 2006 and 2) a composite data set from previously analyzed historical records, mostly from the 1970s. The results highlight the ability of the model to reproduce velocity and salinity profile characteristics, their variations among Puget Sound sub-basins, and tidally averaged circulation. Sensitivity of residual circulation to variations in freshwater inflow and resulting salinity gradient in fjordal sub-basins of Puget Sound is examined. 相似文献
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