Environmental and biological applications to secondary ion mass spectrometry

Secondary ion mass spectrometry (SIMS) was employed to study effects of an EPA Method 0010 sampling train upon carcinogenic polycyclic aromatic hydrocarbons (PAHs) adsorbed onto coal flyash and diesel soot. Ion images of particle-laden filters indicated that more benzo[a]anthracene was found on the filter media than on the flyash, suggesting that solvent extraction of train components may overestimate the particle-bound PAH fraction. Soot images indicated that heating effects from the sampling train on the soot itself were significantly greater than effects due to vapor-phase PAH spiking or any discernible interactions between soot and filter media.; Intracellular uptake of aluminum, an important ecological plant toxin, was directly imaged in longitudinal freeze-dried root tip cryosections of soybean (Glycine max cv. Essex and Jet Black) and wheat ( Triticum aestivum cv. Scout 66). Improved sample preparation and analysis protocols enabled definition of symplastic Al:K ratios for specific anatomical sites. “Topographical 39K+ ion images, collected at low primary beam currents for the same image field as 27Al+ and 41K+ images, were directly comparable to scanning electron images. Contrary to hypotheses that differential uptake determines soybean genotypic tolerance, the Al-tolerant Jet Black accumulated more Al for each exposure period and anatomical region examined than did the A1-sensitive Essex. Despite greater uptake, Jet Black was better able to exclude Al from the meristem compared to Al levels measured in the root cap, thus suggesting a possible genotypic tolerance mechanism. Al localization at root edge and cap/meristem interface was occasionally observed. Al s effect upon the short-term uptake of calcium and magnesium, two essential plant nutrients, was investigated using stable isotope labeling with 44Ca2+ and 26Mg 2+. Ca transported from basal regions to the tip; Mg exchanged directly inward across the root radius. For both genotypes, Al exposures as short as 6h inhibited Mg exchange between the root interior and external solutions. Statistically significant inhibition of Ca uptake was seen only for the tolerant Jet Black. No change at all was seen for the sensitive Essex indicating that alterations of Ca2+ flux do not correlate to genotypic sensitivity.