Lead isotopic and metallic pollution record in tree rings from the Copperbeltmining-smelting area, Zambia

Martin Mihaljevič,

Vojtěch Ettler, Ondřej Šebek, Ondra Sracek,Bohdan Kříbek, Tomáš Kyncl, Vladimír Majer, František Veselovský

This work was performed in order to determine, through comparison of dendrochemistry and the soil composition, whether the source of these substances in the pine-tree xylem is interception or root uptake and the degree to which the studied tree species are affected by industrial activities, transportation or natural processes.

Sampling locations of tree rings I, II and III are located in the direction of prevailing winds and, according to the distribution of 6 metals (Kříbek et al, 2010), are affected by the ore processing.

Location IVlow contents of metals in upper soil layers

Material and methodsTree rings – Pinus LatteriHaglof Incremental Borer (diameter 5 mm), 3-year segments, digestionof the individual segments (weights in the range of 0.03-0.2 g) in Savillex® beakers in concentrated HNO3 at 150°C

Soilssieving (2mm), milling, pH, TC, TS, dissolution in HF, HClO4.

Analysis of solutionstrace elements, and 206Pb/207Pb 208Pb/206Pb ICP MS (X Series 2, Thermoscientific)

Conclusions:

The isotopic composition of Pb in the soils is different at the contaminated and remote sites.

The effect of Pb with low 206Pb/207Pb derived from combustion of leaded petrol on the composition of the upper soil layers is apparent at the contaminated site.

The soil composition is not affected by automobile lead at the remote (IV) site.

In contrast, the tree rings at all sites have Pb with low 206Pb/207Pb ratio in the youngest parts.

It thus follows that the source of the Pb is probably interception (foliar, bark) uptake of this pollutant by trees.

Lead with low 206Pb/207Pb ratio is not contained in the soil at the remote (IV) site, probably because of frequent fires of biomass litter, plants and bush undergrowth of the studied pine trees.

Acknowledgements:

This work was performed with financial support from the project of the Ministry ofEducation, Youth and Sports (MSM 0021620855) and the Czech Science Foundation

(GA ČR 205/08/0321/1).

Thank you for your attention.

Thanks to Marie Fayadová, Roman Businský, Madeleine Štulíková and John Molson for assistance withlaboratory work, pine determination, language corrections.