A 150-year record of polycyclic aromatic compound (PAC) deposition from high Andean Cajas National Park, southern Ecuador

Benjamin A Musa Bandowe; Lea Fränkl; Martin Grosjean; Wojciech Tylmann; Pablo V Mosquera; Henrietta Hampel; Tobias Schneider

doi:10.1016/j.scitotenv.2017.10.060

A 150-year record of polycyclic aromatic compound (PAC) deposition from high Andean Cajas National Park, southern Ecuador

Sci Total Environ. 2018 Apr 15:621:1652-1663. doi: 10.1016/j.scitotenv.2017.10.060. Epub 2017 Oct 20.

Authors

Benjamin A Musa Bandowe¹, Lea Fränkl², Martin Grosjean², Wojciech Tylmann³, Pablo V Mosquera⁴, Henrietta Hampel⁵, Tobias Schneider²

Affiliations

¹ Oeschger Centre for Climate Change Research, University of Bern, Falkenplatz 16, 3012 Bern, Switzerland; Institute of Geography and Geoecology, Karlsruhe Institute of Technology (KIT), Reinhard-Baumeister-Platz 1, 76131 Karlsruhe, Germany; Organic Geochemistry Unit (OGU), School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK. Electronic address: benjamin.bandowe@kit.edu.
² Oeschger Centre for Climate Change Research, University of Bern, Falkenplatz 16, 3012 Bern, Switzerland; Institute of Geography, University of Bern, Hallerstrasse 12, 3012 Bern, Switzerland.
³ Institute of Geography, Faculty of Oceanography and Geography, University of Gdansk, Bazynskiego 4, 80309 Gdansk, Poland.
⁴ Subgerencia de Gestión Ambiental, Empresa Pública Municipal de Telecomunicaciones, Agua potable, Alcantarillado y Saneamiento (ETAPA EP), Cuenca, Ecuador; Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Barcelona, Spain.
⁵ Facultad de Ciencias Químicas, Universidad de Cuenca, Cuenca, Ecuador; Laboratorio de Ecología Acuática, Departamento de Recursos Hídricos y Ciencias Ambientales, Universidad de Cuenca, Cuenca, Ecuador.

PMID: 29056377
DOI: 10.1016/j.scitotenv.2017.10.060

Abstract

The temporal profiles of polycyclic aromatic compounds (PACs) in lake sediments reflect past changes in emissions, transport and deposition of these pollutants and, thus, record natural and anthropogenic processes. We document fluxes of PACs [(polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs) and azaarenes (AZAs)] deposited in two tropical high-altitude lakes in the Cajas National Park (Ecuadorian Andes, 2°50'S, 79°10'W). In remote and high elevation Laguna Fondococha (4130m a.s.l.), the temporal fluxes of OPAHs and AZAs were similar to those of PAHs suggesting similar sources. A significant increase of PAC deposition after the 1950s reflects Ecuador's economic development. PAH fluxes were relatively low (∑27PAHs (without retene and perylene): 0.86-11.21ngcm^-2yr^-1) with a composition pattern typical for long-range atmospheric transport (high 9-fluorenone/fluorene ratios) and biomass burning (30% low molecular weight PAHs). PAHs diagnostic of high temperature combustion (industry, traffic) make up 20-25% of total PAHs. Perylene concentrations increase linearly with increasing sediment depth suggesting diagenetic in-situ production. At lower elevations (Laguna Llaviucu, 3140m a.s.l.) and closer to urban areas, PAC fluxes in the past decades were 4-5 times higher than in the remote high-elevation lake. Laguna Llaviucu also showed higher concentrations of high molecular weight pyrogenic PAHs and a greater diversity of AZAs. Individual OPAHs and AZAs reflect mainly combustion activities. In Laguna Llaviucu, which is at a lower elevation (3140m a.s.l.) and closer to the city, molecular ratios suggest short-range atmospheric transport and deposition of PACs. A very foggy climate (170 rainy days per year) with the precipitation maximum at 3500m removes PACs very efficiently (by wet deposition) from the atmosphere at very short distances from emission sources. This partly explains why L. Llaviucu shows higher fluxes of PACs than the higher elevation L. Fondococha. This study presents the first historical record of organic pollutants from environmental archives in Ecuador.

Keywords: Anthropocene; Azaarenes; Oxygenated PAHs; PAHs; Pollution history; South America.