Column Amounts of ClONO2, HCl, HNO3, and HF from Ground-Based FTIR Measurements Made Near Kiruna, Sweden, in Late Winter 1994     

TH. Blumenstock  H. Fisher  A. Friedle  F. Hase  P. Thomas 《Journal of Atmospheric Chemistry》1997,26(3):311-321

During SESAME phase I ground-based FTIR measurements were performed atEsrange near Kiruna, Sweden, from 28 January to 26 March 1994. Zenith columnamounts of ClONO₂, HCl, HF, HNO₃,O₃, N₂O, CH₄, and CFC-12 werederived from solar absorption spectra. Time series of ClONO₂and HCl indicate a chlorine activation at the end of January and around 1March. On 1 March a very low amount of HCl of 2.09times; 10¹⁵molec. cm^-2 was detected, probably caused by a second chlorineactivation phase starting from an already decreased amount of HCl. The ratioof column amounts of HCl to ClONO₂ decreased inside the vortexfrom about 1 in January to 0.4 in late March compared to values of about 2outside the vortex. Although the Arctic stratosphere was rather warm in winter1993/94 and PSCs occurred seldom, chlorine partitioning into its reservoirspecies HCl and ClONO₂ changed during that winter andClONO₂ is the major chlorine reservoir at the end of thewinter as in cold winters like 1991/92 and 1994/95.  相似文献   

Special issue on quantitative estimates of the geology of large regions and their application to mineralresource assessment     

Richard B. McCammon  W. David Menzie  Lawrence J. Drew  Janet S. Sachs 《Natural Resources Research》1997,6(3):155-155

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Matchboxes and dice     

Lawrence J. Drew 《Natural Resources Research》1997,6(3):151-153

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Hydrochemical Evolution of Sodium-Sulfate and Sodium-Chloride Groundwater Beneath the Northern Chihuahuan Desert, Trans-Pecos, Texas, USA   总被引：15，自引：1，他引：15  

R. Stephen Fisher  William F. Mullican  III 《Hydrogeology Journal》1997,5(2):4-16

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Organic matter in small mesopores in sediments and soils   总被引：1，自引：0，他引：1  

Lawrence M. Mayer  Linda L. Schick  Rota Wagai 《Geochimica et cosmochimica acta》2004,68(19):3863-3872

The three-way correlation among organic matter concentrations, specific surface area and small mesopores observed for many soils and sediments led to the hypothesis that enclosure within the pores might explain the apparent protection of organic matter by minerals. We test this hypothesis by examining whether the bulk of organic matter resides within small mesopores. Pore volumes as a function of pore width were measured before and after organic matter removal, and the volume differences ascribed to organic matter filling of pores. Minor changes in small mesopore size distributions upon treatments such as centrifugation and muffling indicate the robustness of the mineral matrices that form these pores. We developed an additional method to assess organic matter densities using high-resolution pycnometry, and used these densities to convert pore volumes to organic matter contents. Although smaller mesopores are shown to have sufficient volumes to contain significant fractions of the total organic matter, only small fractions of total organic matter were found to reside in them. These results are consistent with preferential association between organic matter and aluminous clay particle edges, rather than the largely siliceous clay faces that contribute most surface area and form pore walls. While simple enclosure within smaller mesopores cannot, therefore, explain protection, network effects working at larger size scales may account for exclusion of digestive agents and hence organic matter protection.  相似文献   

Comments on “Earth's heat flux revised and linked to chemistry” by A.M. Hofmeister and R.E. Criss     

R. Von Herzen  E.E. Davis  A.T. Fisher  C.A. Stein  H.N. Pollack   《Tectonophysics》2005,409(1-4):193-198

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Erratum to L. M. Mayer (1999) “Extent of coverage of mineral surfaces by organic matter in marine sediments” geochimica et cosmochimica acta63, 207-215     

Lawrence M. Mayer 《Geochimica et cosmochimica acta》2005,69(5):1375

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Characterizing and classifying urban watersheds with compositional and structural attributes     

Joseph M. Delesantro  Jonathan M. Duncan  Diego Riveros-Iregui  Joanna R. Blaszczak  Emily S. Bernhardt  Dean L. Urban  Lawrence E. Band 《水文研究》2021,35(9):e14339

Current land-use classifications used to assess urbanization effects on stream water quality date back to the 1980s when limited information was available to characterize watershed attributes that mediate non-point source pollution. With high resolution remote sensing and widely used GIS tools, there has been a vast increase in the availability and precision of geospatial data of built environments. In this study, we leverage geospatial data to expand the characterization of developed landscapes and create a typology that allows us to better understand the impact of complex developed landscapes across the rural to urban gradient. We assess the ability of the developed landscape typology to reveal patterns in stream water chemistry previously undetected by traditional land-cover based classification. We examine the distribution of land-cover, infrastructure, topography and geology across 3876 National Hydrography Dataset Plus catchments in the Piedmont region of North Carolina, USA. From this dataset, we generate metrics to evaluate the abundance, density and position of landscape features relative to streams, catchment outlets and topographic wetness metrics. While impervious surfaces are a key distinguishing feature of the urban landscape, sanitary infrastructure, population density and geology are better predictors of baseflow stream water chemistry. Unsupervised clustering was used to generate a distinct developed landscape typology based on the expanded, high-resolution landscape feature information. Using stream chemistry data from 37 developed headwater catchments, we compared the baseflow water chemistry grouped by traditional land-cover based classes of urbanization (rural, low, medium and high density) to our composition and structure-based classification (a nine-class typology). The typology based on 22 metrics of developed landscape composition and structure explained over 50% of the variation in NO₃⁻-N, TDN, DOC, Cl⁻, and Br⁻ concentration, while the ISC-based classification only significantly explained 23% of the variation in TDN. These results demonstrate the importance of infrastructure, population and geology in defining developed landscapes and improving discrete classes for water management.  相似文献   

Soil property variation mapping through data mining of soil category maps          下载免费PDF全文

Fei Du  A‐Xing Zhu  Lawrence Band  Jing Liu 《水文研究》2015,29(11):2491-2503

Spatial information on soil properties is an important input to hydrological models. In current hydrological modelling practices, soil property information is often derived from soil category maps by the linking method in which a representative soil property value is linked to each soil polygon. Limited by the area‐class nature of soil category maps, the derived soil property variation is discontinuous and less detailed than high resolution digital terrain or remote sensing data. This research proposed dmSoil, a data‐mining‐based approach to derive continuous and spatially detailed soil property information from soil category maps. First, the soil–environment relationships are extracted through data mining of a soil map. The similarity of the soil at each location to different soil types in the soil map is then estimated using the mined relationships. Prediction of soil property values at each location is made by combining the similarities of the soil at that location to different soil types and the representative soil property values of these soil types. The new approach was applied in the Raffelson Watershed and Pleasant Valley in the Driftless Area of Wisconsin, United States to map soil A horizon texture (in both areas) and depth to soil C horizon (in Pleasant Valley). The property maps from the dmSoil approach capture the spatial gradation and details of soil properties better than those from the linking method. The new approach also shows consistent accuracy improvement at validation points. In addition to the improved performances, the inputs for the dmSoil approach are easy to prepare, and the approach itself is simple to deploy. It provides an effective way to derive better soil property information from soil category maps for hydrological modelling. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Rethinking the PhD in the age of neoliberalization     

Lawrence D. Berg 《GeoJournal》2015,80(2):219-224

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