BIOgenic emissions, evolution and impacts in the Metropolitan Area of São Paulo – BIOMASPplus

In the last 50 years, the number of megacities has increased more than ten times, currently housing more than half of the world population. Air pollution is among the top of challenges faced by those regions, accounting for over 5 million deaths per year worldwide. While the anthropogenic nature of air pollution has been considered for a long time, there are growing evidences that the mixing between human-made emissions and those from the biosphere can modify, or even exacerbate the effect of anthropogenic pollution on the environment and health. The biosphere-atmosphere interactions are ever more relevant in a context of emission reduction from traditional mobile sources and a changing climate bound to enhance biogenic emissions at global scale. The Metropolitan Area of São Paulo (MASP) in south-eastern Brazil is emblematic of those interactions and threats: with over 20M people, it is among the ten largest megacities worldwide and despite its advance on pollutant emission control, it is experiencing air quality problems due to ozone and particulate matter. Despite the emission control, the maximum ozone concentrations have remained constant over the last 15 years, raising the question of the biogenic VOCs (BVOCs) role as one of its major precursors. The Atlantic Forest surrounding the megacity, totalizing ~30% of the total MASP territory, combines with urban vegetation as an important source of BVOCs. Its subtropical climate favors biogenic emissions and photochemical processes.
Taking MASP as a natural laboratory target, the Franco-Brazilian project BIOMASP+ is a unique opportunity to reduce gaps in our understanding of the atmospheric processes, resulting from the complex anthropogenic and biogenic urban mixing. The main objective of BIOMASP+ is to evaluate the impact of biosphere-atmosphere interactions on gaseous and particulate urban pollution in a changing climate by addressing the following questions: How does the biosphere-atmosphere interaction affect the ozone production? How does this alter the secondary organic aerosol (SOA) formation and aging? How does this affect human health and the biosphere ? Those questions require a wide knowledge of the nature and intensity of chemical and biological compounds emitted by the Atlantic forest, one of the most rich yet poorly described subtropical vegetation. The quantification of the Atlantic forest tree emissions will be one of the original prerequisite of the BIOMASP+ project.
BIOMASP+ has been designed as (i) an integrative project combining new field observations using state-of-the art instrumentationat two contrasted and representative urban and forest supersites on both gaseous and aerosol phases (including semi-volatile species, bioaerosols, oxidative potential of particles) , laboratory experiments and models of various complexity (ii) a multidisciplinary project implying shared expertise in biogenic emissions, atmospheric chemistry, biology and meteorology from Brazil and France. Moreover, the study of the biosphere-atmosphere interactions involves multiple nested spatial and temporal scales: from the leaf level to the above-canopy level (fluxes), short time to multi-year scale. BIOMASP+ is divided into one coordination task and four main interconnected tasks: 1- Meteorology and Fluxes, 2- Characterization and quantification of biogenic emission sources, 3- Bio-physico-chemical processes and ambient composition and 4 - Extended observations, forecast and impacts. To achieve its main objectives.
BIOMASP+ addresses fundamental science and provides a scientific basis for air quality, health and urban climate mitigation purposes. A unique and original database will be produced complying with open science recommendations. In-depth knowledge of these processes is necessary to implement the most effective strategies which will lead to sustainable benefits for society.