Pb Isotopes Study in Recent Sediments from Paraty Bay (Rio de Janeiro, Brazil): Antropogenic Versus Oceanic Signatures

Abstract

We carried out Pb isotopes studies in sediments from Paraty Bay located in the SE area of the Rio de Janeiro State to discriminate the signature of metal contamination from domestic sewage, industries, shipyards and geogenic sources. The studied samples have been chosen in two sectors of the Bay, including the Paraty area and Juatinga Bay. Sample preparation procedures included: 1) drying and granulometric separations (200 mesh); 2) weighting; 3) complete dissolution and 4) Pb isotope analysis obtained by MC-ICP-MS (ratios 208 Pb/ 204 Pb, 207 Pb/ 204 Pb, 206 Pb/ 204 Pb). Preliminary results when plotted in the 207 Pb/ 204 Pb versus 208 Pb/ 204 Pb and 207 Pb/ 206 Pb versus 206 Pb/ 204 Pb diagrams showed three groups of signatures. The first group (samples PY-01, PY-03 PY-106 and PY-127) presented 207 Pb/ 206 Pb values in the range from 1.191 to 1.209. The isotope values may be interpreted as contribution of a pollutant sources of Pb not yet identified. The second group (PY-11, PY-13, PY-21, PY-22, PY-46, PY-51, PY-109 and PY-111) showed 207 Pb/ 206 Pb values in the range from 1.188 to 1.222. The last group (samples PY-123 and PY-135) presented higher 207 Pb/ 206 Pb values from 1.321 to 1.322 and probably represented oceanic signature. The Pb isotope data of the second group may be interpreted as the result of oceanic water and pollutant sources mixture from the continent. According to the literature the anomalous Pb signature is similar to anthropogenic source. The Pb isotope results here reported are coherent with the reported data from the continent area. We may conclude that significant isotopic differences in Pb signatures are consequence of anthropogenic Pb isotope signature. In this way, Pb isotope is an important tool to trace the changing sources of pollutant Pb (and other metals) in ocean environment.

A Practical Procedure for Analysis of Lead Isotopes in Bivalve Shells Using Laser Ablation Multicollector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS)

“…Lead tends to adsorb on organic debris and be stored within sedimentary deposits in a form that can be released back in the water. 21–25 Taking this into account, we correlated our results with Pb isotopic data reported for marine sediments from the same study, and results were plotted together with Pb isotopic data reported for marine sediments from Ilha Grande, 54 Paraty, 52 and Sepetiba Bay 53 (Fig. 7).…”

“…Three isotopes plot showing the results found in shells together with Pb isotopic data reported for surface marine sediments from Ilha Grande Bay, Paraty, and Sepetiba Bay. 52–54 Error bars on the laser ablation analyses are ± 2 standard error of the mean of 40 integration cycles.…”

“…The blue circle indicates the location of the sampling site, the numbers (1–13) reveal the locations of the anthropogenic pollution sources, and the red circles show the sites where previous studies reported Pb isotopic data for marine sediments. 52–54 Potential sources of metal pollution in the region include local industrial activities, mainly metallurgical and chemical industries, a nuclear power plant, harbors, an oil terminal, a maritime mining terminal, dockyards, and several marinas. The pollutants released from urban wastes and industrial plants circulate throughout the bay and/or accumulate in the bottom sediments near to the discharge points.…”

Persistent Pb Pollution in Central East Antarctic Snow: A Retrospective Assessment of Sources and Control Policy Implications

“…The Pb isotopic variations in the air at the specific sites, which are strongly influenced by the Pb emissions from leaded gasoline, will therefore be determined by the market-share of the different alkyl-lead retailers. , As shown in Figure , the 206 Pb/ 207 Pb ratios at Dome Fuji and Dome A show a similar trend moving toward more radiogenic values when the EFs peaked between the mid-1970s and the early 1980s. The 206 Pb/ 207 Pb ratio of gasoline used in Brazil was a relatively radiogenic value of ∼1.2, indicating the predominant use of alkyl-lead additives manufactured from the highly radiogenic Mississippi Valley type Pb in Brazil . In contrast, leaded gasoline in Argentina and Chile was characterized by a relatively low 206 Pb/ 207 Pb ratio (∼1.06), because of the primary use of alkyl-lead supplied by Associated Octel, despite the fact that different alkyl-lead mixtures were supplied to different cities. ,, Consequently, the increasing 206 Pb/ 207 Pb ratios from the mid-1970s to the early 1980s could be considered to support the hypothesis that the large increase in the EFs in the snow during the corresponding period is primarily due to the large emissions of Pb originating from the combustion of leaded gasoline in Brazil.…”

Variations in lead isotopes in Antarctic snow from northern Victoria Land during 2012–2015

“…In Argentina and Chile, the use of Pb additives in gasoline was completely phased out in 1997 and 2001, respectively (Tchernitchin et al 2006, Oudijk 2010. In contrast, leaded gasoline in Brazil was characterized by a relatively high 206 Pb/ 207 Pb ratio because of its primary use of Mississippi Valley type Pb (Bollhofer and Rosman 2000, Bollhofer and Rosman 2002, Munõz et al 2004, Geraldes et al 2015. Because the ban on leaded gasoline in Brazil started in 1975 and leaded gasoline was phased out in the 1980s, this relatively radiogenic signature of Hercules Névé snow dated 2009-2012 was presumably due to Pb emissions from industrial sources Suttie 1994, Paoliello andCapitani 2005).…”