Large Industrial Point Sources in Italy : a focus on mercury concentrations resulting from three seasonal ship-borne measurements

In Italy there are 25 Large Industrial Point Sources whose mercury emissions in air exceed the established threshold of 10 kg year. Many of these mercury point sources, mostly distributed along the Italian coastal area, are located at sites qualified as National Interest Rehabilitation Sites because of documented contamination in qualitative and/or quantitative terms and of potential health impact. Atmospheric mercury emissions related to Italian Large Industrial Point Sources, with a value of 1.04 Mg·yr for 2007, have a not negligible contribution, accounting, on their own, for more than 10% of the total mercury emissions resulting from all activity sectors at a national level. Among others, thermal power stations, pig iron and steel as well as basic inorganic chemical production, result to be the main contributing industrial activities. In order to assess how mercury species concentrations and distribution in the Marine Boundary Layer (MBL) change with vicinity to large industrial sites, measurements of atmospheric mercury were performed during three oceanographic campaigns aboard the Research Vessel (R.V.) Urania of the Italian CNR. Collection of GEM, GOM and PBM was conducted across the Adriatic sea, during autumn 2004 (27 of October to 12 of November) and summer 2005 (17 to 29 of June), and across the Tyrrhenian sea during autumn 2007 (12 of September to 1 October). Analysis were carried out with reference to the period in which the R.V. Urania has stopped close to the main Italian industrial contaminated sites. Explorative statistical parameters of atmospheric mercury species were computed over each single stop-period and then compared with the overall cruise campaign measurements. Results are herein presented and discussed.

and the last available updating refers to 2006.In order to check the atmospheric mercury emissions from all IPPC activities located in Italy, the INES and E-PRTR registers have been browsed and queried.Emissions referring to the same IPPC activity and for the same year were grouped, as reported in Fig. 1, in order to assess trend in mercury emissions from 2002 to 2007.As it can be note in this graph, total mercury emissions released from all IPPC activity showed an almost constant trend with a slight decrease from 2002 (2.1 Mg yr -1 ) to 2004 (2.0 Mg yr -1 ).An increase of 34.9%, with a value of 2.7 Mg yr -1 , was then observed in 2005 followed by a subsequent decrease in 2006, with a total mercury emissions values of 2.3 Mg yr -1 .In 2007 there was a sharp decline with a value of 1.04 Mg yr -1 .As Fig. 1 shows, until 2006, the major contributing IPPC activity was that related to "Installations for the production of pig iron or steel" (IPPC code: 2.2) that, in 2006, accounted for 64%.Otherwise, in 2007 the main contributing industrial activity became the "Energy sector" (IPPC code: 1.1 and 1.2), with a contribution of 37.2% E3S Web of Conferences followed by "Chemical installations for the production of basic organic chemicals" (IPPC code: 4.1), with 32.6%.
Comparing the absolute contribution from each single large industrial point source, it was evident that the highest value of mercury emissions in air, ranging from 1063 Kg yr -1 (2002) to 174 Kg yr -1 (2007), refers to ILVA S.p.a..This is one of the largest pig iron and steel facility in Europe that is located in the city of Taranto and whose involved area has been defined as a National Interest Rehabilitation Site.The second large contribution, in terms of absolute mercury emission values, came from facilities both referring to installations for the production of basic inorganic chemicals.These latter refer to SYNDIAL S.p.A. -ex EniChem S.p.A located at Augusta-Priolo city, in Sicily, and to SYNDIAL S.p.A. located in Porto Marghera, Venice.Worth of note are also the thermal power stations located at Porto Torres, (Sardinia), Brindisi (Puglia) and Trieste (Friuli-Venezia-Giulia) and the refinery operating in Gela (Sicily).As Fig. 2 shows, all facilities just mentioned are distributed along the Italian coast and additionally they also coincide with those areas qualified as Contaminated Sites of National Interest (SINs), (Ministerial Decrees n. 486, 2001 andn. 308, 2006).In order to assess how mercury species concentrations and distribution in Marine Boundary Layer (MBL) change with vicinity to industrial contaminated sites, measurements of atmospheric mercury were conducted during three oceanographic campaigns across both the Tyrrhenian and the Adriatic sea aboard the R.V. Urania of the Italian CNR.Collection and analysis of GEM (Gaseous Elemental mercury), GOM (Gaseous Oxidized Mercury) and PBM (Particulate Bound Mercury) was performed using an automated Tekran (Toronto, Canada) Model 2537A CVAFS, Tekran Model 1130 speciation unit, and Tekran Model 1135 system (Landis et al., 2002).The integrated mercury system was mounted on the top deck of the R.V. Urania with the inlet at about 10 m above the sea surface.GEM samples (5 min) were continuously quantified by the 2537A analyser.The technique is based on amalgamation on two Au traps within the analyser working alternately, and mercury detection by CVAFS.

Measurements
The integrated Tekran speciation system was configured to collect 2h GOM and PBM samples on a quartz KCl-coated annular denuder and quartz filter assembly, respectively.Particles larger than 2.5 µm are removed from the air stream by a cyclone before entering the denuder, and smaller particles pass through without deposition on the reactive inner surface under the proper flow rate conditions (10 l min −1 ).After the 2 h sampling period, a one hour analysis procedure begins by flushing the 1130 and 1135 systems with mercury free air.The PBM and GOM collected on the quartz filter and annular denuder, respectively, were thermally decomposed (at 800 and 500 °C respectively) into the mercury free air stream and detected as GEM.During the campaign denuders were recoated and replaced weekly.The Tekran 2537A analysers were calibrated on a daily basis using the internal permeation tubes.The permeation tube in each of the Tekran 2537A instruments was calibrated just prior to the study as described in Landis et al. (2002) using a Tekran model 2505 primary calibration unit.The detection limit for GOM and PBM under the operating conditions used was less than 2 pg m −3 .

Results and Discussion
During both the autumn 2004 and 2007 campaigns events with high values of GOM and/or Hg associated with particulates (PBM), that could be linked to probable anthropogenic emission source areas, were observed.Maximum values equal to 62.9 and 97.8 pg m -3 for GOM, and equal to 50.9 and 77.5 pg m -3 for PBM, were recorded during 2004 and 2007 cruise campaigns, respectively.During the summer campaign however, the by now rather familiar diurnal variation of GOM concentration, with maxima around midday, was also observed (Sprovieri et al., 2003;2008;2010).Again there were events with peak in GOM (Max: 39.9) and in PBM (Max: 9.11) concentrations.The origin of these events was investigated using back trajectory simulations and with also the support of the Navy Aerosol Analysis and Prediction System (NAAPS) predicting the distribution of tropospheric aerosols and its surface concentration in terms of dust, sulphate or smoke concentration (Naval Research of atmospheric mercury species were conducted across both the Tyrrhenian and the Adriatic sea aboard the R.V. Urania of the Italian CNR, during three oceanographic campaigns of which two were performed along the same route during two seasons, autumn (27 October to 11 November) 2004 and summer (17 to 29 June) 2005 whereas the third one took place during late summer-autumn (12 September to 1 October) 2007.The campaigns aimed to assess how mercury species concentrations and distribution in MBL with changing meteorology conditions and change with vicinity to industrial Contaminated Sites.The cruise paths of the Med-Oceanor campaigns are shown in Figure 5.5.The 2004 and 2005 cruise paths (solid and dotted white lines) were identical in the Adriatic, but the 2005 cruise started from Napoli and finished at Messina.The 2007 cruise campaign (dotted yellow line) was otherwise entirely performed in the Tyrrhenian sea.

Introduction
Emissions from large industrial point sources are currently regulated by the Directive 2008/1/EC of the European Parliament and of the Council concerning Integrated Pollution Prevention and Control (IPPC).