Lead and its isotopes in the sediment of three sites on the Lebanese coast: Identification of contamination sources and mobility

Abstract

Lead concentrations and isotopic composition of sediment samples collected from three sites within the Lebanese coastal zones were measured: at Akkar, Dora and Selaata. Akkar is located far from any direct source of contamination, while Dora and Selaata receive urban and industrial wastes, respectively. Low Pb concentrations (6-16 mu g g(-1)) were detected in the Akkar sediments, and high concentrations of Pb (70-101 mu g g(-1)) were detected in the Dora sediments. Measuring stable isotope ratios of Pb makes it possible to identify the principal sources of Pb in the Akkar sediments as Pb emitted from gasoline combustion and Pb originating from natural sources. On the other hand, Pb stable isotopic ratios in Dora sediments indicate that they are more highly influenced by anthropogenic sources. Isotopic Pb ratios in the Selaata deposits, where Pb concentrations range between 5 and 35 mu g g(-1), have an exceptional radiogenic signature for marine sediments 1.25 < Pb-206/Pb-207 < 1.6 and 0.5, Pb-206/Pb-208 < 0.67, which shows the impact of the phosphogypsum discharged by Selaata's chemical plant. Isotopic Pb analysis applied to EDTA extracts, to test the mobility of Pb, shows that that this mobility is high (>60%) after 24 h of extraction, and that the extracted Pb is less radiogenic than the residual Pb

Pb, Cd and Cu distribution and mobility in marine sediments from two ports in Lebanon: Beirut army naval port and Tripoli fishing port

“…Lead concentrations decreased at points B9 to B12, and reached the lowest value at B11 (19.2 µg.g -1 ) ( Table 1). This latter Pb concentration is comparable to values found in superficial sediments in Akkar (15.7 µg.g -1 ), where Pb detected originated from gasoline combustion (Abi-Ghanem et al, 2009a).…”

“…Cn: measured concentration of the studied metal n (n = Pb, Cd or Cu) Bn: background concentration corresponding to the detected metal levels in deep sedimentary layers of Akkar which is a site located at the north of Lebanon and where deep sea sediments layers are free from any anthropogenic impact (6.21 µg.g -1 for Pb, 0.19 µg.g -1 for Cd, 11 µg.g -1 for Cu) (Abi-Ghanem et al, 2009a). The choice of the background concentration appears to be reasonable by comparing the Bn values with the "average shale" (Turekian & Wedepohl, 1961).…”

“…In Lebanon, many studies were conducted along the coastal zone to evaluate trace metals contamination in the water column, in superficial sediments and in bioindicators Brachidontes variabilis (Nakhlé, 2003;Fakhri, 2005;Abi-Ghanem et al, 2009a;2009b;. These studies highlighted the presence of several hot spots (Dora, Antelias, Selaata, etc…), where trace metal levels reached concentrations comparable to marine sediments in highly polluted areas in the world, where Pb reached 100 µg g -1 and Cd reached a concentration of 3 µg g -1 (Abi-Ghanem et al, 2009b).…”

Mercury Distribution and Methylmercury Mobility in the Sediments of Three Sites on the Lebanese Coast, Eastern Mediterranean

“…The concentrations of Ca, Si and Mg were determined using an inductively coupled plasma mass spectrometer, and the concentrations of Fe and Al by atomic absorption spectrophotometry. The detailed analytical procedures are given in the companion paper concerning the Pb contamination of the same sediments (Abi-Ghanem et al, 2009).…”

Chronology and sources of trace elements accumulation in the Rhône pro-delta sediments (Northwestern Mediterranean) during the last 400 years

“…Trace element concentrations in surface coastal sediments are largely documented in the Western Mediterranean and the Eastern Mediterranean (e.g., Scoullos and Oldfield, 1986;Abdel-Moati and El-Sammak, 1997;Abi-Ghanem et al, 2009 andSchintu et al, 2009 andMzoughi and Chouba, 2011;Roussiez et al, 2011). Concentrations range between geological backgrounds, with the example of Sardinia coasts (Schintu et al, 2009), and very high concentrations.…”