Deep winter intrusions of urban black carbon into a canyon near Santiago, Chile: a pathway towards Andean glaciers

Nicolás Huneeus, Rémy Lapere, Andrea Mazzeo, César Ordóñez, Nicolas Donoso, Ricardo Muñoz, José A. Rutllant

Research output: Contribution to journalArticlepeer-review


Black carbon transport from the Santiago Metropolitan Area, Chile, up to the adjacent Andes Cordillera and its glaciers is of major concern. Its deposition accelerates the melting of the snowpack, which could lead to stress on water supply in addition to climate feedback. A proposed pathway for this transport is the channelling through the network of canyons that connect the urban basin to the elevated summits, as suggested by modelling studies, although no observations have validated this hypothesis so far. In this work, atmospheric measurements from a dedicated field campaign conducted in winter 2015, under severe urban pollution conditions, in Santiago and the Maipo canyon, southeast of Santiago, are analysed. Wind (speed and direction) and particulate matter concentrations measured at the surface and along vertical profiles, demonstrate intrusions of thick layers (up to 600 m above ground) of urban black carbon deep into the canyon on several occasions. Transport of PM down-valley occurs mostly through shallow layers at the surface except in connection with deep valley intrusions, when a secondary layer in altitude with return flow (down-valley) at night is observed. The transported particulate matter is mostly from the vicinity of the entrance to the canyon and uncorrelated to concentrations observed in downtown Santiago. Reanalyses data show that for 10% of the wintertime days, deep intrusions into the Maipo canyon are prevented by easterly winds advecting air pollutants away from the Andes. Also, in 23% of the cases, intrusions proceed towards a secondary north-eastward branch of the Maipo canyon, leaving 67% of the cases with favourable conditions for deep penetrations into the main Maipo canyon. Reanalyses show that the wind directions associated to the 33% anomalous cases are related to thick cloud cover and/or the development of coastal lows.
Original languageEnglish
Article number118124
Number of pages10
JournalEnvironmental Pollution
Early online date9 Sept 2021
Publication statusPublished - 15 Dec 2021

Bibliographical note

Funding Information:
The authors are grateful to Editor and reviewers for their thorough revision and feedback which contributed to improve this manuscript. Nicolás Huneeus was partially funded by Ministry of Science and Technology of Chile through FONDECYT N° 1181139 , from the European Union H2020 program PAPILA ( GA 777544 ) and Research and Innovation programs , under grant agreement N° 870301 (AQ-WATCH). The work was co-funded by the France-Chile ECOS project number C19U02 . NH acknowledges the support of project ANID-PIA-Anillo INACH ACT192057 . This study was supported by the MAP-AQ which is an IGAC and WMO sponsored activity. Powered@NLHPC: This research was partially supported by the supercomputing infrastructure of the NLHPC ( ECM-02 ). Measurements at VZC were possible with the collaboration of Colegio Almenar del Maipo. Wind measurements at La Obra were supported by FONDECYT N° 1170214 and FONDECYT N° 1131092 . E-Sampler MP10 measurements were made possible by Meteodata. Students taking part in the field campaigns were Andrea Orfánoz, Valeria Moreno, Pamela Pizarro, Rubén Saez, Yenny Saavedra, Matías Avila, Alex Mazzey, Carolina García, Natalia Tapia, José Rodriguez, Sindy Correa, Cristóbal Puelma, Denisse Castillo, Tamara Cares and José Miguel Valdés.

Publisher Copyright:
© 2021 Elsevier Ltd


  • Light-absorbing particles
  • Mega-city pollution
  • Andean cryosphere
  • Mountain-valley circulation
  • Atmospheric transport

ASJC Scopus subject areas

  • Pollution
  • Health, Toxicology and Mutagenesis
  • Toxicology


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