Long-Term Measurements of Chemical and Physical Properties of Atmospheric Aerosol at Dome C

Financed by: MIUR (PNRA 2015/AC3.04 – PNRA14_00091-Linea A3)
Period: November 2015 – June 2021

Polar Areas

67 months

€ 164.000,00

I

On going

Introduction

Aerosols are characterized by a very high temporal and spatial variability and a radiative forcing global model revealed that 45% variance arises from uncertainties in natural rather than anthropic emissions. This result pushes toward a better characterization of background natural aerosol, such as that reaching inner Antarctica. Long-term measurements of chemical and physical properties of aerosols and their gaseous precursors at Dome C will yield a better knowledge of sources, atmospheric reactions and transport, depositional and post-depositional processes (including the interaction at the air/snow interface) of present Antarctic aerosol, leading to a better understanding of the climate-environment feedback processes, an improved development of climatic models and a better interpretation of past changes in aerosol components measured along Antarctic ice cores.

Description

The measurements will include: atmospheric particulate; selected gases (ozone, NOx) involved in the aerosol processes; monitoring of cosmic-rays (neutrons, muons), as potential agents for in-situ nucleation. Instrumentation will be installed in the St. Concordia Atmospheric Studies shelter. Daily snow samples will be collected in the close “clean area”. Direct measurements (few min. resol.) and samplings (24 h to 15 days resol.) include: aerosol size distribution (DMPS + OPC); PM10 for ion and metals; PM10 for PIXE elemental analysis; PM10 for EC/OC fractions; PM10 for geochemical characterization of dust particles; 4-stage sampling for size-segregated ions and metals; 5-stage high-volume sampling for selected organic compounds (WSOC, amino acids, methoxyphenols, sugars, anhydro-sugars) and halogens (I and Br); ozone, VOC and NOx measurements; neutrons and muons counting. Contemporaneously with atmospheric activity, the snow surfaces will be collected, in order to study the relationships of selected chemical species at the air/snow interface.

The dynamics of sea ice will be also studied by the seasonal trends of Br, I and MSA in order to evaluate the role of sea ice in promoting phytoplanktonic bloom.

The identification of dust potential source areas (PSA) will be performed by a PM10 geochemical characterization (REEs and Pb, Sr and Nd isotopic ratios).

The role of photochemistry will be studied by comparing solar irradiance (BSRN DC Observatory) with the aerosol concentrations of nss-SO42-, MSA, nitrate, organic compounds and halogens. Tropospheric ozone will be continuously monitored in order to evaluate the oxidizing capacity of DC atmosphere.

Snow source of gaseous N-compounds will be investigated by comparing NO3 and NO2 concentrations in the aerosol and in the snow with gaseous NOx and HNO2 measured at two heights over the snow surface.

The efficiency of PM10 nitrate sampling will be tested with a denuder at the sampler inlet (to eliminate gas-phase HNO3) and a back-up nylon filter (to correct for re-emission of HNO3 by exchange with acidic species). Nitrate source studies will include the stratosphere-troposphere exchanges.

The identification and the temporal evolution (particle formation rate and new-particle growth rate) of nucleation events will be performed by high-resol. DMPS measurements (40 size classes; 3 – 1000 nm). The role of Cosmic Rays in forming new particles will be tentatively evaluated by comparing the cosmic rays trend with DMPS data.

 

Objectives

The goals of a long-term aerosol study include:

  • understanding the climate-aerosol feedback processes in regions very sensitive to environmental and climatic changes;
  • establishing the background values of the atmospheric load, size distribution and chemical composition of aerosol;
  • improving the reliability of climatic models by making available a long-term data set for a more effective evaluation of the forcings exerted by global aerosol (ERFari and ERFaci);
  • studying, with sufficient statistics, the seasonal and inter-annual trend of the concentrations of key-components of aerosol (S-, N- and C-cycle compounds; biogenic emissions; dust; sea spray);
  • evaluating the present source strength and long-range atmospheric transport efficiency of aerosol formed in the marine and continental areas at lower latitudes;
  • estimating the contribution of local to regional Antarctic aerosol sources;
  • studying the effects of photochemistry and radical sources (ozone) on chemical reactions of gaseous aerosol precursors and new-particles formation at very peculiar (temperature, continuous summer irradiance) atmospheric conditions;
  • improving the reliability of paleo-climatic and paleo-environmental reconstructions by ice core stratigraphies, also by a better knowledge of the aerosol- snow surface interchange;

• evaluating the possible role of cosmic rays in New Particle Formation (NPF) in an area where nucleation is unlikely due to low atmospheric concentrations of aerosol precursors.

Activities CNR-IIA

Specific scientific objectives:

– to determine the atmospheric abundance and atmosphere-snow exchanges of organic and reactive nitrogen compounds (NOx, HNO3, HNO2 and relative salts, VOCs including aldehydes, and carboxylic acids);

– to optimize the measurement of particulate nitrate in the coarse and fine fractions by removing gaseous interferences and by quantifying volatile (evolved) and non-volatile (unevolved) nitrate salts;

– to understand possible chemical transformation processes during long range atmospheric transport.

 

Field activity in Antarctica

Summer 2016-2017 and winterover 2017.

The efficiency of PM10 nitrate sampling was tested by using two denuders (to eliminate gas-phase HNO3 and NH3) and back-up Teflon and Nylon filters (to correct for re-emission of HNO3 and NH3) installed along the aerosol sampling inlet of one PM10 aerosol sampler. These measurements were compared with another PM10 aerosol sampler (without denuder and back up filters) on daily and weekly basis.

Summer 2017-2018

Atmospheric measurements of the largest portion of the organic fraction (VOC, aldehydes, carboxylic acids) were carried out by means of traps and filters. Measurements of nitrogen oxides were not carried out due to malfunctioning of chemiluminescence analyzer.

Superficial snow was also collected once per day for the same sampling period to evaluate the atmosphere-snow exchanges.

Summer 2018-2019

Similar to summer 2017/2018, atmospheric measurements of organic compounds (VOC, aldehydes, carboxylic acids) were performed. Measurements of nitrogen oxides were also carried due to malfunctioning of chemiluminescence analyzer.

Superficial snow was also collected once per day for the same sampling period to evaluate the atmosphere-snow exchanges.

 

Activity in Italy

Summer 2017-2018

Determination of all ionic compounds, including MSA, and carboxylic acids were performed using IC and HPLC/UV techniques. All obtained values were blank-corrected.

The atmospheric concentrations of carbonyl compounds were determined by 2,4-Dinitrophenylhydrazine (DNPH) derivatization and successive analysis by HPLC with UV detection of the derivatives. In the case of snow samples, after smelting, they were derivatized with DNPH and subject to solid phase extraction (SPE). VOCs was thermally desorbed from traps and analyzed by GC-MS.

Summer 2018-2019

Similar to summer 2017/2018.

 

Partnership

  • CNR-IIA
  • Università di Firenze, UNIFI, Italia
  • CNR-ISAC
  • Università di Venezia, UNIVE, Italia
  • Università di Genova, UNIGE, Italia
  • LGGE (Grenoble, France
  • KOPRI (Incheon, South Korea)
  • Institute of Alpine and Arctic Research (INSTAAR); University of Colorado (Boulder, USA)
  • Desert Research Institute (Reno, Nevada)
  • Dept. Analytical Chemistry Ghent Univ. (Ghent, Belgium)
  • FMI (Helsinki, Finland)
  • EMPA (CH)

Antonietta Ianniello

Scientific coordinator

email: ianniello@@@iia.cnr.it

Gruppo di lavoro

Francesca Vichi

email: vichi@@@iia.cnr.it

Andrea Imperiali

email: imperiali@@@iia.cnr.it

Giulio Esposito

email: esposito@@@iia.cnr.it

Mauro Montagnoli

Mauro Montagnoli

email: montagnoli@@@iia.cnr.it

Massimiliano Frattoni

email: frattoni@@@iia.cnr.it