Investigation of lead and zinc dispersion from an abandoned mine site at Tyndrum, Scotland

QD Chemistry;GE Environmental Sciences

Mansor, Nurlidia ; Pulford, Ian D.

University:University of Glasgow

Department:School of Chemistry

关键词: atmospheric dispersal,fluvial dipersal,lead,zinc,abandoned mine,210Pb,Pb isotope ratio,Scots pine;   

Others  :  http://theses.gla.ac.uk/491/1/2008mansor1phd.pdf

来源: University of Glasgow

【 摘 要 】

This research focuses on atmospheric and fluvial dispersal of Pb and Zn from an abandoned mine at Tyndrum, Scotland, which potentially acts as a significant source of contamination to the surrounding area. Concentrations of Pb and Zn in tree bark samples and peat profiles were measured to assess aerial deposition and fallout around the main mine site.Dispersal of contaminants through fluvial transport was assessed by analysis of river water and sediment on site and in the main river system draining the area, extending 25 km downstream from the mine area. Attempts were also made to determine whether the contamination is due to contemporary dispersal of material from the abandoned mine waste dumps, or originates from past deposition. Pb and Zn concentrations in tree bark from Scots pine (Pinus sylvestris) were high, but decreased with increasing distance up to approximately 100 m from the main dumpsite. Concentrations reduced markedly beyond this distance, possibly owing to the density of the forest stand. It is suggested that tree bark samples provide a useful medium for monitoring and quantifying contemporary aerial dispersal.Distributions of Pb and Zn within peat soil profiles provide information of past atmospheric deposition. Subsurface peaks of Pb and Zn can be linked to the period when mining was active during the 19th and early 20th centuries using the 210Pb dating method. The dispersal of Pb and Zn within the fluvial system was assessed by measuring concentrations of the contaminants in the solution, suspended particle and bed sediment phases. It was found that Pb and Zn are mainly transported in suspension in the 1.2-53 m suspended sediment fraction and are consequently deposited throughout the dispersion pathway in riverbed, lake and riverbank sediments. The contaminant Pb in an overbank core was confirmed as originating from the Tyndrum mine on the basis of its 206Pb/207Pb isotope ratio characteristics. This confirms a previous hypothesis that waste from the mine is an important contributor to Pb contamination over the entire length of the river system as far as Loch Tay. Thus overall, the investigation concludes that although the atmospheric dispersal of the contaminants is mostly contained within the vicinity of the Tyndrum main mine, the fluvial system remains a significant pathway for dispersal of Pb and Zn from the Tyndrum waste and that the presence of these metals within the river may persist for many years to come.