Atmospheric deposition of particles at a sensitive alpine lake: Size-segregated daily and annual fluxes from passive sampling techniques.

Autor: Tai AY; Division of Atmospheric Sciences, Desert Research Institute, Reno, NV 89512, USA., Chen LA; Department of Environmental and Occupational Health, University of Nevada, Las Vegas, NV 89154, USA. Electronic address: antony.chen@unlv.edu., Wang X; Division of Atmospheric Sciences, Desert Research Institute, Reno, NV 89512, USA., Chow JC; Division of Atmospheric Sciences, Desert Research Institute, Reno, NV 89512, USA., Watson JG; Division of Atmospheric Sciences, Desert Research Institute, Reno, NV 89512, USA.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2017 Feb 01; Vol. 579, pp. 1736-1744. Date of Electronic Publication: 2016 Dec 06.
DOI: 10.1016/j.scitotenv.2016.11.117
Abstrakt: Lake Tahoe, a North American alpine lake long appreciated for its clear water and geographic setting, has experienced a trend of declining water clarity due to increasing nutrient and particle inputs. Contributions from atmospheric deposition of particulate matter (PM) could be important, yet they are inadequately quantified. This study established a yearlong deposition monitoring network in the northern Lake Tahoe Basin. Dry deposition was quantified on surrogate surfaces while wet deposition was based on particles suspended in precipitation at 24-hour resolution. The particle size ranges by these passive techniques were 1-64μm and 0.5-20μm in diameter for dry and wet deposition, respectively. Dry deposition of submicrometer (0.5-1μm) particles was also estimated by extrapolation of a lognormal size distribution. Higher daily number deposition fluxes (NDF dry and NDF wet ) were found at a near-shore site, confirming substantial impacts of commercial and tourist activities. The two more isolated sites indicated a uniform regional background. On average, daily NDF dry is about one order of magnitude lower than daily NDF wet . Dry deposition velocities increased rapidly with particle size, as evidenced by collocated measurements of NDF dry and ambient particle number concentrations, though it seems less so for wet deposition due to different scavenging mechanisms. Despite fewer "wet" days than "dry" days during the monitoring period, wet processes dominated seasonal particle deposition, particularly in winter and spring when most precipitation occurred. Adopting sediment (insoluble, inorganic) particle fraction estimates from the literature, this study reports an annual particle flux of 2.9-5.2×10 10 #m -2 yr -1 for sediment particles with 1-20μm diameter and 6.1-11×10 10 #m -2 yr -1 for those with 0.5-20μm diameter. Implications of these findings to the current knowledge of atmospheric deposition in the Lake Tahoe Total Maximum Daily Load (TMDL) are discussed.
(Copyright © 2016 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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