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Santiago, Chile

Moreno F.,University of Santiago de Chile | Gramsch E.,University of Santiago de Chile | Oyola P.,Centro Mario Molina Chile | Rubio M.A.,University of Santiago de Chile
Journal of the Air and Waste Management Association | Year: 2010

Santiago de Chile is one of the most polluted South American cities, concentrating its pollution episodes during winter. Daily PM2.5 (particulate matter [PM] ≤ 2.5 μm in aerodynamic diameter) concentrations over 80 μg/m3 have been reached frequently since 1998. Despite several regulations introduced over the past 20 yr to improve the air quality, PM concentration levels remain high. In this work, sampling in downtown Santiago was conducted from April 1998 to August 2007 for PM2.5 and from October 2003 to March 2006 for PM10-2.5 (PM between 2.5 and 10 μm in aerodynamic diameter) with dichotomous samplers. Elemental analysis was performed on the samples with X-ray fluorescence. The resulting series of 859 samples and 216 elements identified were divided into semiannual periods and analyzed with factor analysis. Five factors are clearly discerned: soil, motor vehicles, residual oil, marine aerosols, and secondary sulfates. The soil factor in the fine fraction shows a clear increase from 2002 to 2006, whereas the coarse fraction of this factor shows a stable trend. The most probable cause for this trend is the growth in the number of vehicles in Santiago (6.5%/yr), which increases the resuspension of particles from the ground. Another cause for the increase is the growth in the construction activity (4.2%/yr). The motor vehicle factor in the fine fraction shows a decrease between 1998 and 2006. The decrease in the apportionment of this factor can be explained by the improvement in the vehicle fleet. In Santiago, the number of noncatalytic vehicles has been reduced from 389,000 in 2001 to 275,000 in 2006. The residual oil factor also shows a decrease between 1998 and 2006. The decrease could be attributed to the adoption of cleaner technologies and norms regarding gasoline and diesels. Copyright © 2010 Air & Waste Management Association. Source

Banwell A.F.,University of Chicago | Banwell A.F.,University of Cambridge | Caballero M.,University of Chicago | Caballero M.,Centro Mario Molina Chile | And 4 more authors.
Annals of Glaciology | Year: 2014

Supraglacial meltwater lakes trigger ice-shelf break-up and modulate seasonal ice-sheet flow, and are thus agents by which warming is transmitted to the Antarctic and Greenland ice sheets. To characterize supraglacial lake variability we perform a comparative analysis of lake geometry and depth in two distinct regions, one on the pre-collapse (2002) Larsen B ice shelf, Antarctica, and the other in the ablation zone of Paakitsoq, a land-terminating region of the Greenland ice sheet. Compared to Paakitsoq, lakes on the Larsen B ice shelf cover a greater proportion of surface area (5.3% cf. 1%), but are shallower and more uniform in area. Other aspects of lake geometry (e.g. eccentricity, degree of convexity (solidity) and orientation) are relatively similar between the two regions. We attribute the notable difference in lake density and depth between ice-shelf and grounded ice to the fact that ice shelves have flatter surfaces and less distinct drainage basins. Ice shelves also possess more stimuli to small-scale, localized surface elevation variability, due to the various structural features that yield small variations in thickness and which float at different levels by Archimedes' principle. Source

Ruiz P.A.,University of Chile | Toro C.,Michigan Technological University | Caceres J.,Centro Mario Molina Chile | Lopez G.,Centro Mario Molina Chile | And 2 more authors.
Journal of the Air and Waste Management Association | Year: 2010

The impact of outdoor and indoor pollution sources on indoor air quality in Santiago, Chile was investigated. Toward this end, 16 homes were sampled in four sessions. Each session included an outdoor site and four homes using different unvented space heaters (electric or central heating, compressed natural gas, liquefied petroleum gas, and kerosene). Average outdoor fine particulate matter (PM2.5) concentrations were very high (55.9 μg·m-3), and a large fraction of these particles penetrated indoors. PM2.5 and several PM2.5 components (including sulfate, elemental carbon, organic carbon, metals, and polycyclic aromatic hydrocarbons) were elevated in homes using kerosene heaters. Nitrogen dioxide (NO2) and ultrafine particles (UFPs) were higher in homes with combustion heaters as compared with those with electric heaters or central heating. A regression model was used to assess the effect of heater use on continuous indoor PM2.5 concentrations when windows were closed. The model found an impact only for kerosene heaters (45.8 μg m-3). Copyright 2010 Air & Waste Management Association. Source

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