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161.
Nudi AH de Luca Rebello Wagener A Francioni E de Lemos Scofield A Sette CB Veiga A 《Environment international》2007,33(3):315-327
This study is aimed at verifying the relevance of Ucides cordatus as a bioindicator of oil contamination and PAH bioavailability in mangrove sediments. For this, crabs and sediment cores were sampled from five mangroves, including an area suspected of contamination derived from an MF380 oil spillage, and analyzed for the 16 PAH in the USEPA priority list as well as for the five series of alkylated homologues. Concentrations in sediments varied from 35 microg kg-1 in the lower core layer of the control area to 33,000 microg kg-1 in the upper layer of the most contaminated area. Total PAH contents in crabs varied from 206 to 62,000 microg kg-1 and were closely correlated to that in sediments. In general, individual PAH profiles in both matrices were in good agreement. Phenanthrenes, however, were more predominant in crabs making up to 30-46% of the Total PAH. Accumulation factors found in the range of 0.7 to 35 were highly variable even after normalizing concentrations for organic carbon and lipid content. Survival in highly contaminated environment and reliable record of environmental contamination in the tissue provide evidence that U. cordatus is an excellent bioindicator for oil in mangroves. 相似文献
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Agnew LJ Lyon S Gérard-Marchant P Collins VB Lembo AJ Steenhuis TS Walter MT 《Journal of environmental management》2006,78(1):63-76
Researchers have noted that current water quality protection strategies, like nutrient management plans, lack a sound hydrological underpinning for pollutant transport processes. This is especially true for areas like the northeastern U.S. where copious research has shown that variable source area hydrology largely governs runoff generation. The goal of this study was to develop a scientifically justified method to identify the locations that generate overland flow. Furthermore, this methodology must be computationally simple enough that it can be utilized or incorporated into nutrient management plans and other established water quality tools. We specifically tested the reliability of the 'distance from a stream,'D(s), and the 'topographic index,'lambda, to predict areas with a high propensity for generating overland flow, i.e. hydrologically sensitive areas (HSA). HSAs were defined by their probability of generating runoff, P(sat), based on 30 year simulations using a physically based hydrological model. Using GIS, each location's P(sat) was correlated with D(s) and lambda. We used three Delaware Co., NY watersheds in the New York City watershed system with areas varying in size from 1.6 to 37 km2 and with forested and agricultural land uses. The topographic index gave stronger, more regionally consistent correlations with P(sat) than did D(s). Equations correlating lambda and P(sat) for each month are presented and can be used to estimate hydrological sensitivity in the region surrounding our study watersheds, i.e. in Delaware Co. This work is currently being incorporated into an Internet Mapping System to facilitate user-friendly, on-line identification of HSAs. 相似文献
164.
S. Kent Hoekman Amber Broch Curtis Robbins Richard Purcell 《International Journal of Greenhouse Gas Control》2010,4(1):44-50
A laboratory-scale reactor system was built and operated to demonstrate the feasibility of catalytically reacting carbon dioxide (CO2) with renewably-generated hydrogen (H2) to produce methane (CH4) according to the Sabatier reaction: CO2 + 4H2 → CH4 + 2H2O. A cylindrical reaction vessel packed with a commercial methanation catalyst (Haldor Topsøe PK-7R) was used. Renewable H2 produced by electrolysis of water (from solar- and wind-generated electricity) was fed into the reactor along with a custom blend of 2% CO2 in N2, meant to represent a synthetic exhaust mixture. Reaction conditions of temperature, flow rates, and gas mixing ratios were varied to determine optimum performance. The extent of reaction was monitored by real-time measurement of CO2 and CH4. Maximum conversion of CO2 occurred at 300–350 °C. Approximately 60% conversion of CO2 was realized at a space velocity of about 10,000 h?1 with a molar ratio of H2/CO2 of 4/1. Somewhat higher total CO2 conversion was possible by increasing the H2/CO2 ratio, but the most efficient use of available H2 occurs at a lower H2/CO2 ratio. 相似文献
165.
Neufeld HS Peoples SJ Davison AW Chappelka AH Somers GL Thomley JE Booker FL 《Environmental pollution (Barking, Essex : 1987)》2012,160(1):74-81
Ozone-sensitive and -tolerant individuals of cutleaf coneflower (Rudbeckia laciniata L.) were compared for their gas exchange characteristics and total non-structural carbohydrates at Purchase Knob, a high elevation site in Great Smoky Mountains National Park, USA. Photosynthesis and stomatal conductance decreased with increased foliar stipple. Sensitive plants had lower photosynthetic rates for all leaves, except the very youngest and oldest when compared to tolerant plants. Stomatal conductance decreased with increasing leaf age, but no ozone-sensitivity differences were found. Lower leaves had less starch than upper ones, while leaves on sensitive plants had less than those on tolerant plants. These results show that ambient levels of ozone in Great Smoky Mountains National Park can adversely affect gas exchange, water use efficiency and leaf starch content in sensitive coneflower plants. Persistence of sensitive genotypes in the Park may be due to physiological recovery in low ozone years. 相似文献
166.
167.
Earl L. Merryman Arthur Levy 《Journal of the Air & Waste Management Association (1995)》2013,63(12):800-806
The microstructure of 1/10 and 1/20 atmosphere, lean H2S—O2—N2 flames is developed using the mass-spectrometric flame-sampling technique. The flame mechanism developed is in agreement with that determined from an earlier study on 1-atm H2S flames. The formation of SO2 appears to be primarily related to the production of SH and the ensuing oxidation steps SH + O2 = SO + OH and SO + O2 = SO2 + O. While there is some question whether SO2 formation occurs via an SO or an S2O intermediate, the present study does not give direct support to the role of S2O in the oxidation mechanism. However, the presence of significant quantities of free sulfur in the pre-flame zone may be indicative of S2O formation via SO + S → S2O, and, possibly, via the disproportionation of SO, 3SO → S2O + SO2. Kinetic analyses of some of the pre-flame reactions indicate an apparent activation energy of 17,300 calories/mole for the decomposition of H2S. The actual initiation process in the flame mechanism requires further examination. The specific rate for the reaction step H2S + O = OH + SH is given by k 6 = 1.45 × 1015 exp ( – 6600/RT) cm3 mole–1 sec–1, and the specific rate for the oxidation of SO, SO + O2 = SO2 + O, is given by k 5 = 5.2 × 1014 exp (—19,300/RT) cm3 mole–1 sec–1. 相似文献
168.
169.
David P. Baldwin Daniel S. Zamzow Arthur P. D’Silva 《Journal of the Air & Waste Management Association (1995)》2013,63(10):789-791
Abstract This research presents investigations into the use of inductively coupled air plasma – atomic emission spectrometry (air-plasma ICPAES) to determine the presence of inorganic contaminants in airborne aerosols. Limits of detection (LOD) in the ppm to ppb range for 19 hazardous metals and radionuclides were determined for aerosols of solutions nebulized into the air plasma. For many elements, the determined LOD surpass the threshold limit values established by the American Conference of Governmental Industrial Hygienists by one to three orders of magnitude. The potential of air-plasma ICPAES for continuous on-line monitoring of airborne contaminants is discussed. 相似文献
170.