Contaminant source apportionment by PIMMS lead isotope analysis and SEM-image analysis.
By combining scanning electron microscopy (SEM) image analysis and laser ablation plasma ionisation multi-collector mass spectrometry (LA-PIMMS), high precision lead isotope analyses can be obtained from individual metal-rich particles. Soils from Wolverhampton and Nottingham were sampled on the basis of high Pb concentrations or brownfield location. Pressed powder pellets of each were rastered by LA-PIMMS to obtain a bulk Pb-isotope signature. The results plot along an apparent mixing line between the major sources of lead contamination in the UK, that is UK ore deposits and alkyl-lead from petrol additives (Australian ore). Two particularly lead-rich soils were chosen to investigate the lead distribution and isotope variability between size and density fractions. The fine-grained and low-density fractions contained most of the lead and have Pb-isotope ratios comparable with the bulk soils. By contrast, the small, lead-enriched denser fractions contained only a minor proportion of the total lead but Pb-isotope signatures indicating relative enrichment in one or other of the end-members from the mixing line. Further characterisation of individual Pb-rich grains is in progress.
McGill
R A
RA
NERC Isotope Geosciences Lab, University of Middlesex, Keyworth, UK. rarmc@nigl.nerc.ac.uk
Pearce
J M
JM
Fortey
N J
NJ
Watt
J
J
Ault
L
L
Parrish
R R
RR
D004784:Environmental Monitoring / Q000379:methods; D007854:Lead / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods; D008855:Microscopy, Electron, Scanning; D012680:Sensitivity and Specificity; D012989:Soil Pollutants / Q000032:analysis*
D012989:Soil Pollutants; D007854:Lead