PhD Student: Jessica Castagna

Transcription

1 PhD Student: Jessica Castagna F. Sprovieri, I. M. Hedgecock, and N. Pirrone Institute for Atmospheric Pollution Research, Rende Section, Rende, CS, Italy; Atmos. Chem. Phys., 10, ,

2 Mercury is a highly toxic element Natural Sources: oceans, land, biomass burning and volcanoes Anthropogenic Sources: fossil fuel combustion (mainly coal), metal production, industrial and artisanal gold production, cement production, chlor-alkali industry and waste incineration Re-emission sources: oceans,land, vegetation Vegetation 7% Soil 11% Anthropogenic 21% Biomass Burning 6% Ocean 55% 2

3 Not to become like the Mad Hatter of Alice in the Wonderland For inhalation Hg 0 causes: Damages to nervous system Tremors Gingivitis Excitability 3

4 For dietary intake: methylmercury [CH 3 Hg] Methylmercury causes: affects the immune system alters genetic and enzyme systems damages the nervous system damages kidneys teratogen (damages to developing embryos) 4

5 Methylmercury in the food web: not easily purged from organisms biomagnification of up to 10 7 can occur in the aquatic food chain Tuna Swordfish 5

6 Elemental gaseous Hg 0 high vapor pressure relatively insoluble in water (4, g/l) low deposition velocity on the order 0,05-1 cm/s long half time (5-24 months) global scale Divalent reactive gaseous mercury (RGM) lower vapor pressure, water soluble (66 g/l) high deposition velocity on the order of 1-5 cm/s short life time (1-7 days) transported on a local scale Particulate phase Hg P deposition velocity which is particle size (0,1-2,5 μm) dependent and ranges from 0,1-1 cm/s, short life time (1-7 days) transported on local scale. 6

7 Oceanographic campaigns in the Adriatic autumn (26 October to 15 November) 2004 summer (15 June to 5 July)

8 Automated Tekran (Toronto, Canada) Tekran Model 2537A CVAFS for Hg 0 : capture on two Au-traps and measured by Cold Vapor Atomic Fluorescence Spectrometry at 253,7nm Tekran Model 1130 Speciation Unit for RGM: annular denuder captures RGM and after 2 h is thermally decomposed in Hg 0 at 500 C Tekran Model 1135 Particulate Unit: pyrolyzer (quartz filter) captures particulate then decomposed in Hg 0 at 800 C 8

9 Aim: to investigate the atmospheric chemistry of Hg in the gas and deliquesced aerosol phases in the MBL (Marine boundary layer) Rate constants determined in the laboratory and using theoretical techniques Constrained by measurement data: Hg 0 and O 3 concentration, relative humidity, temperature, latitude and longitude. 9

10 NOOA Hybrid single-particle Lagrangian integrated trajectory model (HYSPLIT): calculate 72 h backward trajectories for the R.V. Urania s position Aim: to identify possible sources of Hg 10

11 The average Hg 0 concentrations 1,6 ng/m 3 autumn ,0 ng/m 3 summer

12 Fall Cruise (2004) Summer Cruise (2005) Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008; 12

13 RGM & Hg(p) [pg m -3 ] TGM [ng m -3 ] # URANIA 2004 RGM Hg(p) TGM 70 Milazzo Brindisi Bari Ancona Venezia Trieste Oct Oct Oct Oct Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov-04 Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008;

14 RGM & Hg(p) [pg m -3 ] TGM [ng m -3 ] # URANIA 2004 RGM Hg(p) TGM 70 Milazzo Brindisi Bari Ancona Venezia Trieste Oct Oct Oct Oct Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov-04 Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008;

15 RGM & Hg(p) [pg m -3 ] TGM [ng m -3 ] # URANIA 2004 RGM Hg(p) TGM 70 Milazzo Brindisi Bari Ancona Venezia Trieste Oct Oct Oct Oct Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov-04 Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008;

16 Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008; TGM [ng m -3 ] # URANIA 2005 RGM Hg(p) TGM Augusta Priolo Bari Ancona Trieste Brindisi RGM & Hg(p) [pg m -3 ] Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun-05

17 Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008; TGM [ng m -3 ] # URANIA 2005 RGM Hg(p) TGM Augusta Priolo Bari Ancona Trieste Brindisi RGM & Hg(p) [pg m -3 ] Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun-05

18 Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008; TGM [ng m -3 ] # URANIA 2005 RGM Hg(p) TGM Augusta Priolo Bari Ancona Trieste Brindisi RGM & Hg(p) [pg m -3 ] Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun-05

19 Assumption: Hg 0 +O 3 and Hg 0 +OH reactions don t give products that contribute to RGM HgBr* recombination product is converted to RGM before it can decay back to the initial reactants 19

20 Sprovieri et al., ACP 2010; Sprovieri et al., EFM 2008;

21 To reconcile measurements of model with the observations: the Hg 0 +O3 and Hg 0 +OH reactions do not give products that contribute to RGM The Adriatic sea is influenced by an anthropogenic emission source (regional industries and shipping/port activities) 21

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