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Stalactite Growth as a Free-Boundary Problem: A Geometric Law and Its Platonic Ideal

Physical Review Letters 2005年第1期94卷 018501-018501页

作者： Martin B. Short James C. Baygents J. Warren Beck David A. Stone Rickard S. Toomey, III Raymond E. Goldstein Department of Physics University of Arizona Tucson Arizona 85721 USA Department of Chemical and Environmental Engineering University of Arizona Tucson Arizona 85721 USA Program in Applied Mathematics University of Arizona Tucson Arizona 85721 USA Accelerator Mass Spectrometry Facility University of Arizona Tucson Arizona 85721 USA Department of Soil Water and Environmental Science University of Arizona Tucson Arizona 85721 USA Kartchner Caverns State Park P.O. Box 1849 Benson Arizona 85602 USA

The chemical mechanisms underlying the growth of cave formations such as stalactites are well known, yet no theory has yet been proposed which successfully accounts for the dynamic evolution of their shapes. Here we consider the interplay of thin-film fluid dynamics, calcium carbonate chemistry, and CO2 transport in the cave to show that stalactites evolve according to a novel local geometric growth law which exhibits extreme amplification at the tip as a consequence of the locally-varying fluid layer thickness. Studies of this model show that a broad class of initial conditions is attracted to an ideal shape which is strikingly close to a statistical average of natural stalactites.

关键词： Limestone

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High level treatment of stormwater heavy metals

High level treatment of stormwater heavy metals

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2004 World Water and environmental Resources Congress: Critical Transitions in Water and environmental Resources Management

作者： Pitt, R. Clark, S. Johnson, P.D. Morquecho, R. Gill, S. Pratap, M. Dept. of Civil and Environmental Engineering University of Alabama Tuscaloosa AL 35487 School of Science Engineering and Technology Environmental Engineering Program Penn State - Harrisburg Harrisburg PA 17057 United States

ISBN: (纸本)0784407371

The results of several latest and related stormwater research projects that focused on the treatability of stormwater heavy metals were presented. Results indicated that the heavy metals of concern remain strongly bound to the particulates during long exposures at the extreme pH conditions likely to occur in receiving water sediments. The heavy metals also likely remain strongly bound to the particulates in stormwater control device sumps or detention pond sediments where particulate-bound metals are captured. It was found that the heavy metals can likely remain strongly associated with a variety of organic and inorganic media under varying Eh conditions.

关键词： Storm sewers

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Using trees to mitigate pollution

Using trees to mitigate pollution

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Proceedings of the A and WMA's 97th Annual Conference and Exhibition;Sustainable Development: Gearing Up for the Challenge

作者： Heckel, Pamela F. Cincinnati Earth Systems Science Program Department of Civil and Environmental Engineering University of Cincinnati Cincinnati OH 45221-0071

Several international agreements developed during the past decade have emphasized the reduction of greenhouse gas emissions to delay or reverse the current global warming cycle. Carbon dioxide, as an abundant, global greenhouse gas, has been pegged as the chief villain in global warming. Much of the carbon sequestration research has focused on the largest plants, trees. The goal of this work is to reinforce the idea that planting trees in urban areas and along rural roads can make a measurable difference in air quality.

关键词： Pollution control

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Estimating pollutant loading from industrial activities in an urban watershed

Estimating pollutant loading from industrial activities in a...

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Joint Conference on Water Resource engineering and Water Resources Planning and Management 2000

作者： Lewis, Chad L. Sax, Todd P. Duke, L. Donald Environmental Science and Engineering Program School of Public Health University of California Los Angeles CA 90095-1772 United States

ISBN: (纸本)0784405174

In urbanized watersheds, storm water discharges from industrial facilities are a potentially major but poorly understood source of pollutants. Estimates of pollutant load from industrial facilities may vary with many factors, but must be refined if watershed based regulations, such as the Total Maximum Daily Load (TMDL) program, are to be implemented fairly and effectively. Storm water runoff from industrial facilities under the NPDES program are regulated through a general permit, which among requires facility operators to implement a limited monitoring program. This research used monitoring data reported by industrial facilities to estimate the contribution of pollutant load into the upper San Gabriel watershed in the Los Angeles region. First, we attempted to control for data variability caused by factors such as facility size, impervious portion of surface area, rainfall intensity, and seasonal antecedent rainfall, but no relationships were identified. Next, we estimated total loads from industrial facilities in the watershed. Industrial facilities constituted less than one percent of the watershed area, but contributed between 10% and 70% of total copper load and between 15% and 60% of total zinc load. Load estimates were strongly affected by variability in concentration data and estimates of the number of non-compliant facilities, but less strongly by spatial variability in rainfall. Copyright ASCE 2004.

关键词： Watersheds

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Effectiveness assessment of NPDES regulations for storm water discharges

Effectiveness assessment of NPDES regulations for storm wate...

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World Water and environmental Resources Congress 2001

作者： Augustenborg, Cara A. Duke, L. Donald UCLA Environmental Health Sciences Department United States Environmental Science and Engineering Program School of Public Health University of California Los Angeles CA 90095-1772 United States

ISBN: (纸本)0784405697

This research is designed to evaluate effectiveness of current regulations for control of pollutants in stormwater runoff from industrial facilities, and resulting efforts by the regulated community to reduce pollutants. For three targeted municipalities, the research first assesses the approximated proportion of industrial facilities that have recognized their duty to comply since the promulgation of permits under NPDES in the early 1990s. The research examines the proportion of facilities subject to regulations that have filed Notice of Intent (NOI) and the number of new NOIs filed each year since the regulations took effect in 1992. Then, the research determines for each municipality the industry types with the greatest number of NOIs filed. The purpose of these analyses is to characterize trends and patterns of compliance by industrial facilities within the regions, in order that future efforts may attempt to link those trends with observed water quality changes in the targeted municipalities. The total number of facilities in compliance can be influenced by unique facility types in different regions;by the diligence of regulatory and outreach effects by state and local agencies in different regions;and various other factors. The method is based on databases containing industrial facility compliance information. In this way, the research evaluates the relative effectiveness of municipal programs at achieving the pollutant reduction goals of the storm water NPDES regulations. Copyright ASCE 2004.

关键词： Water quality

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A universal calibration curve for the TSI aerodynamic particle sizer

A universal calibration curve for the TSI aerodynamic partic...

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作者： Tsai, Chuen-Jinn Chen, Sheng-Chieh Huang, Cheng-Hsiung Chen, Da-Ren Institute of Environmental Engineering National Chiao Tung University No. 75 Poai St Hsin Chu Taiwan Department of Environmental Engineering and Health Yuanpei University of Science and Technology Taiwan Department of Mechanical Engineering Joint Program in Environmental Engineering University of Washington in St. Louis St. Louis MO 63130 United States

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Source apportionment and characterization of ambient fine particles in Delhi

Source apportionment and characterization of ambient fine pa...

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Symposium on Air Quality Measurement Methods and Technology 2004

作者： Chowdhury, Zohir Zheng, Mei Cass, Glen R. Sheesley, Rebecca J. Schauer, James J. Salmon, Lynn G. Russell, Armistead G. School of Earth and Atmospheric Sciences Georgia Institute of Technology Atlanta GA 30332 Environmental Chemistry and Technology Program University of Wisconsin-Madison Madison WI 53706 Environmental Science and Engineering California Institute of Technology Pasadena CA 91125 Department of Civil and Environmental Engineering Georgia Institute of Technology Atlanta GA 30332

ISBN: (纸本)0923204628

Fine particle air pollution is characterized and source contribution to that fine particle air pollution is quantified in Delhi. Average fine particle mass concentrations were 231±2 μg m-3 during the winter and 50±1 μg m-3 during the summer. Organic carbon (OC), elemental carbon (EC), NO3-, SO42-, Cl-, NH4+, and trace metals were analyzed. Organic matter (OM) and EC were respectively 58% and 8% during winter and 46% and 8% during summer. Sulfate contributed much of the rest. Relative contributions of crustal oxides or dust to the fine particle mass reached a peak during the spring and the summer time in all the cities. Fifty-five organic compounds were also quantified using GC/MS techniques. Summertime concentrations for levoglucosan, picene, and the sum of hopanes and steranes were respectively 210±40 ng/m3, 0.3±0.06 ng/m3, and 8.5±1.7 ng/m3 and wintertime concentrations for the same compounds were respectively 5300±1100 ng/m3, 5.1±1.0 ng/m3, and 80±16 ng/m3. These measured concentrations of organic carbon from Delhi were used in a molecular marker source apportionment model to quantify the primary source contributions to the PM2.5 mass concentrations. Five important sources were identified and quantified: diesel exhaust, gasoline exhaust, road dust, coal combustion, and biomass combustion. Important trends in the seasonal and spatial patterns of the impact of these five sources were observed. Primary emissions from fossil fuel combustion (coal, diesel, and gasoline) were responsible for 22-33% of PM 2.5 mass compared to the biomass combustion contributions to ambient PM2.5 of 9-28%.

关键词： Particles (particulate matter)

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Atmospheric dry deposition of trace metals in the Los Angeles coastal region

Atmospheric dry deposition of trace metals in the Los Angele...

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Proceedings of the A and WMA's 97th Annual Conference and Exhibition;Sustainable Development: Gearing Up for the Challenge

作者： Sabin, Lisa D. Lim, Jeong Hee Schiff, Ken Stolzenbach, Keith D. Tiefenthaler, Liesl Southern California Coastal Water Research Project 7171 Fenwick Lane Westminster CA 92683 Environmental Science and Engineering Program University of California School of Public Health Los Angeles CA 90095 Department of Civil and Environmental Engineering University of California Los Angeles CA 90095

Emissions of trace metals to the atmosphere and subsequent deposition, either directly to the waterbody surface or indirectly to the watershed for wash off during rain events, may contribute to the contamination observed in surface waters throughout the urban Los Angeles region. The goal of this study was to provide empirical data on atmospheric concentrations of trace metals on coarse particles and to estimate the direct and indirect mass loading of these trace metals due to dry atmospheric deposition in coastal watersheds of the Los Angeles Air Basin. To achieve this goal, atmospheric concentrations of chromium, copper, lead, nickel and zinc were measured seasonally using a Noll Rotary Sampler at six urban and one nonurban site throughout the Los Angeles coastal air basin. Dry deposition fluxes were calculated by summing the product of air concentration and theoretical deposition velocities of four coarse particle fractions (6-11, 11-20, 20-29, and >29 μm). Mean annual fluxes at urban sites ranged from 3.2 to 9.1, 11 to 34, 3.8 to 8.8, 8.3 to 29, and 69 to 228 μg/m2/day for chromium, copper, nickel, lead and zinc, respectively. Mean fluxes at the urban sites were significantly higher than the nonurban site. Comparisons for the Los Angeles River indicated direct dry atmospheric deposition produced a relatively small load of trace metals to that waterbody. In contrast, indirect dry deposition was potentially a very large source of trace metals to watershed loadings based on comparisons to load estimates from stormwater runoff.

关键词： Deposition

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Assessing compliance with storm water regulations and water quality implications for the auto dismantling industry, Los Angeles, California

Assessing compliance with storm water regulations and water ...

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World Water and environmental Resources Congress 2001

作者： Chang, Hyon Duke, L. Donald Santa Monica Bay Restoration Project Los Angeles CA 90013 United States Environmental Science and Engineering Program University of California Los Angeles CA 90095 United States

ISBN: (纸本)0784405697

This research evaluated actions taken by auto dismantling facilities in the Los Angeles, California, region as part of required compliance with regulations for industrial storm water discharge. Eight years after California issued a General Permit for storm water under the National Pollutant Discharge Elimination System (NPDES), a large number of dismantlers have failed to recognize their duty to comply;about 20% of identified facilities do not appear to have notified regulating agencies of their intent to comply. The research then evaluated a sample of complying facilities. The research involved storm water sampling at a smaller number of case study facilities, and determined that a large proportion have measured constituents in discharges in concentrations exceeding U.S. guidelines for storm water - not an enforced requirement, because the regulations do not specify numerical effluent limits. Estimates of pollutant load contributed by the dismantling industry appear substantial. Copyright ASCE 2004.

关键词： Water quality

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Evaluation of non-point source runoff on suspended solids that enter Santa Monica Bay

Evaluation of non-point source runoff on suspended solids th...

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Joint Conference on Water Resource engineering and Water Resources Planning and Management 2000

作者： Buffleben, Matthew S. Nix, Diane Ouyang, Xinling Ruth, Edward Stenstrom, Michael K. Suffet, I.H. North Coast Regional Water Quality Control Board 5550 Skylane Blvd. Santa Rosa CA 95403 United States Environmental Science and Engineering Program Department of Environmental Health Sciences School of Public Health Los Angeles United States Department of Civil and Environmental Engineering University of California Los Angeles United States

ISBN: (纸本)0784405174

Hydrophobic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), demonstrate a high affinity for fine particles, the so-called suspended solids or sediments (SS) in natural waters. This study focused on PAHs from the SS collected from non-point source runoff into Santa Monica Bay, California. The runoff came from the urbanized Los Angeles watershed of Ballona Creek, which is approximately 325 square kilometers in size and developed primarily with residential and light commercial industries. In the 1997-98 rain season, an El Nino year, storm events were monitored to show the pattern of non-point source runoff. The primary objective of this study was to determine the types and concentrations of organic pollutants associated with the suspended solid phase. A calculation of the mass of the pollutants for each storm was conducted. Other objectives included 1) to study for the relationship between storm flow and pollutant loading, including the determination of a first flush, 2) to compare concentration of pollutants with an environmental indicator and 3) to do a simple comparison between point source and non-point source sources of pollution. Seventeen PAHs were detected frequently during the storm. Only, fluoranthene and pyrene were detected in all twenty-four samples analyzed and chrysene and phenanthrene were detected in all but the first sample. Five of seven low molecular weight polycyclic aromatic did not show a first flush for the December storm at Ballona Creek. The high molecular weight PAHs showed a moderate first flush. The estimated mass load calculated for the PAHs for Ballona Creek was 4.1 kg for the December 1997 storm. The mass of the all PAHs from this storm is equivalent to the allowable effluent for 6.4 months of PAHs from an oil refinery located on Santa Monica Bay. Copyright ASCE 2004.

关键词： Runoff

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