Long-range atmospheric transport of persistent organic pollutants to remote lacustrine environments.

Concentrations, temporal trends and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs) were determined in soil and (210)Pb-dated sediment cores from remote lacustrine environments (El Tule and Santa Elena lakes) in rural areas of Central Mexico. In both areas, the concentrations of target analytes in soil and sediment samples were comparable and indicative of slightly contaminated environments. The prevalence of low-molecular-weight PAHs in soils suggested their mainly atmospheric origin, in contrast to the aquatic sediments where runoff contribution was also significant.

Historical trends of polychlorinated dibenzo-p-dioxins and dibenzofurans in three dated sediment cores from Mexico.

This paper describes the first report of dioxins and furans (PCDDs/Fs) in sediment cores from Mexico. Sedimentation rates and vertical fluxes were estimated using (210)Pb dating. Two cores correspond to marine sediments and one to an endorheic lake.

Method to determine 226Ra in small sediment samples by ultralow background liquid scintillation.

(210)Pb dating of sediment cores is a widely used tool to reconstruct ecosystem evolution and historical pollution during the last century. Although (226)Ra can be determined by gamma spectrometry, this method shows severe limitations which are, among others, sample size requirements and counting times. In this work, we propose a new strategy based on the analysis of (210)Pb through (210)Po in equilibrium by alpha spectrometry, followed by the determination of (226)Ra (base or supported (210)Pb) without any further chemical purification by liquid scintillation and with a higher sample throughput.