CHAPTER 17
Atmospheric Deposition of Trace Metals in North Adriatic Sea
P. Rossinil, S. Guerzonil, G. Rampazzo 2 , G. Quarantatto 1 , E. Garibb02, and E. Molinaroli 2
ABSTRACT
Atmospheric bulk deposition of trace metals (Cd, Cu, Ni, Pb) was measured at two coastal urban
sites (Cesenatico and Venice) in the north Adriatic Sea. Collection was carried out using polyethylene bulk passive samplers, samples being collected bi-weekly. Annual deposition fluxes of
metals were calculated and compared with the Po river supply rates to the north Adriatic sea
(surface area = 25000 km2) and those of several rivers to the lagoon of Venice (surface area = 546
km 2 ).Atmospheric annual deposition at Venice was obtained by averaging data collected in the
period 1993-97; Cesenatico values refer to 1995-96 depositions, measured in one coastal station
and in one station 10 nautical miles offshore. Average north Adriatic fluxes (Venice +
Cesenatico), in mg m- 2 year 1 , range from 0.15 to 0.22 for Cd, 4.5 to 11.3 for Cu, 1.4 to 3.5 for Ni,
and 3 to 21 for Pb, and are similar to French coastal sites data. The atmospheric deposition
observed at Venice was 2- to 7-fold higher than that of Cesenatico for Cu, Ni and Pb, and comparable for Cd. Compared with riverine inputs of respectively 0.42,4.0 and 5.5 tonnes year', at
Venice one-third of Cd (0.12 tonnes yearl), nearly half of Ni (1.9 tonnes year1) and an almost
equal amount of Cu (6.2 tonnes year- 1 ) are atmospherically derived, whereas the deposition flux
of Pb is estimated to be 11.5 tonnes year- 1 , i.e. 60% higher than the riverine input of 7 tonnes
year1. Comparison with Po river data shows that the atmosphere delivers 70% of Cd, 10% of Ni,
70% of Cu and an amount of Pb 2-fold higher than riverine inputs. The magnitude of the atmospheric input indicates that eolian deposition is an important contribution which cannot be
neglected in the study of biogeochemical cycles of anthropic elements introduced in the north
Adriatic Sea.
Introduction
In the last decade, it has been demonstrated that
the atmosphere is a significant pathway for the
transport of many natural and polluting materials from the continents to the ocean (Duce et al.
1991). The atmospheric input of many of these
elements may have an impact (either positive or
negative) on marine geochemical cycling and
effects on both terrestrial and aquatic ecosystems (Nriagu 1992). Atmospheric deposition of
aerosols and gases occurs in two modes: wet and
dry. The processes by which chemical elements
are transferred in gas and solid phases are collectively referred to as "dry" deposition.
Dry deposition of particles occurs by direct
impaction and gravitational settling on land or
water surfaces. Liquid deposition, often referred
to as "wet" deposition, comprises water and its
dissolved gases and solutes, together with any
insoluble particulate material contained therein
(Duce et al. 1991; Golomb et aL 1997). To obtain
total atmospheric loading, it is necessary to measure both wet and dry deposition.
As reported by Peters and Reese (1995), bulk.
deposition may not provide precise estimates of
wet plus dry atmospheric deposition. and is further affected by local contamination. In said
paper, deposition was lower and less variable in
the wet precipitation than in the bulk. The higher variability of the latter was attributed to local
contamination, particularly by dust and insects.
In order to compare the validity of different sampling methods, in a previous work (Rossini et al.,
1 Consiglio Nazionale delle Ricerche, Istituto di Geologia Marina, Via Gobetti 101,40127 Bologna, Italy
2 Dipartimento di Sdenze Ambientali, Universita di Venezia, Dorsoduro 2137, 30123 Venezia, Italy
P.M. Faranda, L. Guglielmo, G. Sperle (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia 2001
Atmospheric Deposition of Trace Metals in North Adriatic Sea
P. Rossinil, S. Guerzonil, G. Rampazzo 2 , G. Quarantatto 1 , E. Garibb02, and E. Molinaroli 2
ABSTRACT
Atmospheric bulk deposition of trace metals (Cd, Cu, Ni, Pb) was measured at two coastal urban
sites (Cesenatico and Venice) in the north Adriatic Sea. Collection was carried out using polyethylene bulk passive samplers, samples being collected bi-weekly. Annual deposition fluxes of
metals were calculated and compared with the Po river supply rates to the north Adriatic sea
(surface area = 25000 km2) and those of several rivers to the lagoon of Venice (surface area = 546
km 2 ).Atmospheric annual deposition at Venice was obtained by averaging data collected in the
period 1993-97; Cesenatico values refer to 1995-96 depositions, measured in one coastal station
and in one station 10 nautical miles offshore. Average north Adriatic fluxes (Venice +
Cesenatico), in mg m- 2 year 1 , range from 0.15 to 0.22 for Cd, 4.5 to 11.3 for Cu, 1.4 to 3.5 for Ni,
and 3 to 21 for Pb, and are similar to French coastal sites data. The atmospheric deposition
observed at Venice was 2- to 7-fold higher than that of Cesenatico for Cu, Ni and Pb, and comparable for Cd. Compared with riverine inputs of respectively 0.42,4.0 and 5.5 tonnes year', at
Venice one-third of Cd (0.12 tonnes yearl), nearly half of Ni (1.9 tonnes year1) and an almost
equal amount of Cu (6.2 tonnes year- 1 ) are atmospherically derived, whereas the deposition flux
of Pb is estimated to be 11.5 tonnes year- 1 , i.e. 60% higher than the riverine input of 7 tonnes
year1. Comparison with Po river data shows that the atmosphere delivers 70% of Cd, 10% of Ni,
70% of Cu and an amount of Pb 2-fold higher than riverine inputs. The magnitude of the atmospheric input indicates that eolian deposition is an important contribution which cannot be
neglected in the study of biogeochemical cycles of anthropic elements introduced in the north
Adriatic Sea.
Introduction
In the last decade, it has been demonstrated that
the atmosphere is a significant pathway for the
transport of many natural and polluting materials from the continents to the ocean (Duce et al.
1991). The atmospheric input of many of these
elements may have an impact (either positive or
negative) on marine geochemical cycling and
effects on both terrestrial and aquatic ecosystems (Nriagu 1992). Atmospheric deposition of
aerosols and gases occurs in two modes: wet and
dry. The processes by which chemical elements
are transferred in gas and solid phases are collectively referred to as "dry" deposition.
Dry deposition of particles occurs by direct
impaction and gravitational settling on land or
water surfaces. Liquid deposition, often referred
to as "wet" deposition, comprises water and its
dissolved gases and solutes, together with any
insoluble particulate material contained therein
(Duce et al. 1991; Golomb et aL 1997). To obtain
total atmospheric loading, it is necessary to measure both wet and dry deposition.
As reported by Peters and Reese (1995), bulk.
deposition may not provide precise estimates of
wet plus dry atmospheric deposition. and is further affected by local contamination. In said
paper, deposition was lower and less variable in
the wet precipitation than in the bulk. The higher variability of the latter was attributed to local
contamination, particularly by dust and insects.
In order to compare the validity of different sampling methods, in a previous work (Rossini et al.,
1 Consiglio Nazionale delle Ricerche, Istituto di Geologia Marina, Via Gobetti 101,40127 Bologna, Italy
2 Dipartimento di Sdenze Ambientali, Universita di Venezia, Dorsoduro 2137, 30123 Venezia, Italy
P.M. Faranda, L. Guglielmo, G. Sperle (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia 2001