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

doi:10.1016/j.envpol.2021.118124

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

Geography, Earth and Environmental Sciences

Research output: Contribution to journal › Article › peer-review

Abstract

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 language	English
Article number	118124
Number of pages	10
Journal	Environmental Pollution
Volume	291
Early online date	9 Sept 2021
DOIs	https://doi.org/10.1016/j.envpol.2021.118124
Publication status	Published - 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

Keywords

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

ASJC Scopus subject areas

Pollution
Health, Toxicology and Mutagenesis
Toxicology

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1016/j.envpol.2021.118124Licence: None: All rights reserved

Cite this

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

abstract = "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.",

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note = "Funding Information: The authors are grateful to Editor and reviewers for their thorough revision and feedback which contributed to improve this manuscript. Nicol{\'a}s 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 Orf{\'a}noz, Valeria Moreno, Pamela Pizarro, Rub{\'e}n Saez, Yenny Saavedra, Mat{\'i}as Avila, Alex Mazzey, Carolina Garc{\'i}a, Natalia Tapia, Jos{\'e} Rodriguez, Sindy Correa, Crist{\'o}bal Puelma, Denisse Castillo, Tamara Cares and Jos{\'e} Miguel Vald{\'e}s. Publisher Copyright: {\textcopyright} 2021 Elsevier Ltd",

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AU - Huneeus, Nicolás

AU - Lapere, Rémy

AU - Mazzeo, Andrea

AU - Ordóñez, César

AU - Donoso, Nicolas

AU - Muñoz, Ricardo

AU - Rutllant, José A.

N1 - 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

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N2 - 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.

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KW - Light-absorbing particles

KW - Mega-city pollution

KW - Andean cryosphere

KW - Mountain-valley circulation

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

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

UN SDGs

Access to Document

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Cite this