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2007-4-7 Environ. Sci. & Technol. 最新文章和摘要
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[Journal Home Page] [Search the Journals] [Table of Contents] [PDF version of this article] [Download to Citation Manager] [Purchase Article] Environ. Sci. Technol., ASAP Article 10.1021/es062147h S0013-936X(06)02147-X Web Release Date: April 7, 2007 Copyright © 2007 American Chemical Society Enrichment of Heavy Metals in Sediment Resulting from Soil Erosion on Agricultural Fields John N. Quinton* and John A. Catt Department of Environmental Science, Lancaster University, Lancaster, LA1 4YQ, U.K., Department of Geography, University College London, Pearson Building, Gower Street, London WC1E 6BT, U.K., and Agricultural and Environment Division, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, U.K. Received for review September 8, 2006 Revised manuscript received February 15, 2007 Accepted March 5, 2007 Abstract: Heavy metal pollution of soil and water is often associated with industry, but in this paper we demonstrate that water erosion on agricultural soil which has received only agrochemicals has enriched sediment metal concentrations to toxic levels which breach many accepted standards for soils and sediments. Eight 0.1 ha erosion plots with different cultivation treatments were monitored over a 6 year period for surface runoff, soil loss, and Cr, Cu, Pb, and Ni concentrations. Mean concentrations of these heavy metals were up to 3.98 times higher in the sediment than in the parent soil and in some erosion events the sediment had 13.5 times the concentration of metals in the soil. All the sediment heavy metal concentrations were significantly correlated (p < 0.01) with the clay and silt sized fractions of the sediment and with carbon content. The erosion was a highly selective process enriching the detached material in silt, clay, and organic carbon. This was particularly true in smaller erosion events. Sediment metal concentrations tended to follow the shape of runoff hydrographs, although the pattern changed from storm to storm. -------------------------------------------------------------------------------- [Full text in html] [Full text in pdf] [Journal Home Page] [Search the Journals] [Table of Contents] [PDF version of this article] [Download to Citation Manager] [Purchase Article] Environ. Sci. Technol., ASAP Article 10.1021/es0626483 S0013-936X(06)02648-4 Web Release Date: April 7, 2007 Copyright © 2007 American Chemical Society Spatial and Habitat-Based Variations in Total and Methyl Mercury Concentrations in Surficial Sediments in the San Francisco Bay-Delta Wesley A. Heim,* Kenneth H. Coale, Mark Stephenson, Key-Young Choe, Gary A. Gill, and Chris Foe# Moss Landing Marine Laboratories, Moss Landing, California 95039, California Department of Fish and Game, Moss Landing, California 95039, Department of Marine Sciences, Texas A & M University at Galveston, Galveston, Texas 77551 and Central Valley Regional Water Quality Control Board, Rancho Cordova, California 95670 Received for review November 3, 2006 Revised manuscript received February 26, 2007 Accepted March 5, 2007 Abstract: Recent studies indicate significant amounts of mercury (Hg) are annually transported into the San Francisco Bay-Delta (Bay-Delta) as a result of historic gold and Hg mining activities. We examined temporal and spatial variation in concentrations of total Hg (HgT) and monomethylmercury (MMHg) in surficial sediments of various ecosystem types in the Bay-Delta. We sampled surficial sediments across the Bay-Delta system and found HgT sediment concentrations in the central Delta were generally 100-200 ng g-1 and increased westward through Suisun Bay to 250-350 ng g-1. MMHg concentrations in the central Delta were between 1 and 3 ng g-1, while those in sediments in the perimeter waterways and adjacent bays were less than 1 ng g-1. Six sites were monitored monthly for over a year to identify seasonal changes in Hg sediment concentrations. HgT sediment concentrations ranged from 48 to 382 ng g-1 and varied as a function of location not season. However, MMHg concentrations varied seasonally, increasing from 1 ng g-1 during winter months to 6 ng g-1 during spring and summer. Transects conducted at three marshes in the central Delta revealed MMHg sediment concentrations of 4-8 ng g-1at the interior and 2 ng g-1 at the exterior of the marshes. Habitat type was a major factor controlling MMHg concentration and the MMHg to HgT ratio in sediments of the Bay-Delta. MMHg was significantly correlated to HgT (r 2 = 0.49) in marsh sediments. -------------------------------------------------------------------------------- [Full text in html] [Full text in pdf] [Journal Home Page] [Search the Journals] [Table of Contents] [PDF version of this article] [Download to Citation Manager] [Purchase Article] Environ. Sci. Technol., ASAP Article 10.1021/es062886y S0013-936X(06)02886-0 Web Release Date: April 7, 2007 Copyright © 2007 American Chemical Society Enhanced Corrosion-Based Pd/Mg Bimetallic Systems for Dechlorination of PCBs Shirish Agarwal, Souhail R. Al-Abed,* and Dionysios D. Dionysiou* Civil and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio 45221-0071, and National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, Ohio 45268 Received for review December 5, 2006 Revised manuscript received March 1, 2007 Accepted March 5, 2007 Abstract: Polychlorinated biphenyls (PCBs) are toxic pollutants notorious for their aquatic and sedimentary prevalence and recalcitrant nature. Bimetallic systems like Pd/Fe have been widely studied for degrading them. Mg, with oxidation potential higher than Fe, has been reported to dechlorinate PCBs in conjunction with K2PdCl6-systems that are distinct from Pd/Mg bimetals. This study primarily aims to evaluate Pd/Mg bimetallic systems for dechlorinating 2-chlorobiphenyl (2-ClBP), a model PCB. Candidacy of Mg is based on its unique corrosion properties that afford synthesis and storage under ambient conditions and application-based advantages. A simple wet-chemistry procedure was developed to synthesize Pd/Mg particles with 0.11-1.62% Pd content and nanoscale Pd-islands as determined by X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM). Aqueous 2-ClBP matrices were effectively degraded using these particles, the dechlorination kinetics showing linear dependence on the total Pd content. The pH profile obtained with varying bimetallic content led to useful insights into the unique behavior of Mg surface. A carbon mole balance showed 85-105% recoveries. Performance of the Pd/Mg particles in PCB spiked clays and sediment suggests that they may work well in such systems. Finally, a mechanism for PCB dechlorination in Pd/Mg systems was proposed. -------------------------------------------------------------------------------- [Full text in html] [Full text in pdf] [Journal Home Page] [Search the Journals] [Table of Contents] [PDF version of this article] [Download to Citation Manager] [Purchase Article] Environ. Sci. Technol., ASAP Article 10.1021/es062964h S0013-936X(06)02964-6 Web Release Date: April 7, 2007 Copyright © 2007 American Chemical Society Lead in Bottled Waters: Contamination from Glass and Comparison with Pristine Groundwater William Shotyk* and Michael Krachler Institute of Environmental Geochemistry, University of Heidelberg, INF 236, D-69120 Heidelberg, Germany Received for review December 14, 2006 Revised manuscript received March 5, 2007 Accepted March 6, 2007 Abstract: Using clean lab methods and protocols developed for measuring lead (Pb) in polar snow and ice, we report the abundance of Pb in 125 brands of bottled water from 28 countries. Comparison of six samples of each of three brands of water available in both glass and polyethyelene terephthalate (PET(E)) showed that the waters bottled in glass contained approximately 57, 30, and 26 times more Pb due to leaching from the containers. Excluding the bottled waters in glass, the median Pb concentration in all bottled waters was found to be 8.5 ng/L (n = 185), with a range from <1 to 761 ng/L Pb. Our study includes 25 brands of bottled water from Canada, and the median Pb concentration in these samples was 15.9 ng/L (n = 25), with a range from 2.1 to 268 ng/L. For comparison with the bottled waters, pristine groundwater from six artesian flows in southern Ontario, Canada, where some of the bottled waters originate, yielded a median concentration of 5.1 ng/L Pb (n = 18). The median Pb concentrations reported here for bottled waters from Canada are 32-588 times less than those presented in recently published studies. In fact, all of the waters tested were well below the maximum allowable concentration established by the EU, Health Canada, and the WHO for Pb in drinking water (10 g/L). -------------------------------------------------------------------------------- [Full text in html] [Full text in pdf] |
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