Natural Lead Levels in Dandelions ( Taraxacum officinale): A Weed, Folk Medicine, and Biomonitor.

The natural lead concentration of dandelion ( Taraxacum officinale) leaves is estimated to be 0.2 μg/g (dry weight), or 1-3 orders of magnitude below most contemporary measurements of that value for dandelions and other plants. This estimate is based on analyses of lead concentrations of dandelions grown in a trace metal clean laboratory, with environmental lead concentrations approximating natural levels.

Lead isotopic compositions of ash sourced from Australian bushfires.

This study identifies natural and industrial lead remobilized in ash deposits from three bushfires in relatively pristine areas of Australia in 2011 using lead isotopic compositions ((208)Pb/(207)Pb; (206)Pb/(207)Pb). Lead concentrations in the ash ranged from 1 to 36 mg/kg, bracketing the range of lead (4-23 mg/kg) in surface soils (0-2 cm), subsurface (40-50 cm) soils and rocks. The lead isotopic compositions of ash and surface soil samples were compared to subsurface soils and local bedrock samples.

Chronicling a century of lead pollution in Mexico: stable lead isotopic composition analyses of dated sediment cores.

Analyses of lead isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of dated sediment cores from two coastal estuaries and two inland lakes chronicle the predominance of industrial lead emissions in Mexico over the past century. These isotopic ratios exhibit a shift in composition from the turn of the previous century (1900) that corresponds with measurable increases (from 2- to 10-fold) in lead concentrations in the cores above their baseline values (3-22 microg/g)--both changes are consistent with the development of Mexican lead production for export and the manufacture of tetraethyl lead additives for Mexican gasolines. While subsequent changes in lead concentrations in the cores correspond with calculated emissions from the combustion of leaded gasoline in Mexico, isotopic compositions of the cores remain relatively constant throughout most of the 1900s (e.

A review of factors influencing measurements of decadal variations in metal contamination in San Francisco Bay, California.

This review summarizes some of the principal results of systematic measurements of trace metal concentrations throughout San Francisco Bay that began in 1989, and that have yielded insights on the factors controlling temporal and spatial variations of those concentrations on seasonal to decadal time scales. Pronounced seasonal variation in some metal concentrations is associated with gradients in the system's hydrology and the diagenetic remobilization of metals from benthic sediments. Additional temporal variation is associated with interannual differences in hydrologic flushing (e.