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Here we describe the capabilities of laser-ablation coupled to inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) for high-speed, high-resolution, quantitative three-dimensional (3D) multielemental imaging. The basic operating principles of this instrumental setup and a verification of 3D quantitative elemental imaging are provided. To demonstrate the potential of 3D LA-ICP-TOFMS imaging, high-resolution multielement images of a cesium-infiltrated Opalinus clay rock were recorded using LA with a laser-spot diameter of 5 Îm coupled to ICP-TOFMS. Quantification of elements ablated from each individual laser pulse was carried out by 100% mass normalization, and the 3D elemental concentration images generated match well with the expected distribution of elements. After laser-ablation imaging, the sample surface morphology was investigated using confocal microscopy, which showed substantial surface roughness and evidence of matrix-dependent ablation yields. Depth assignment based on ablation yields from heterogeneous materials, such as Opalinus clay rock, will remain a challenge for 3D LA-ICPMS imaging. Nevertheless, this study demonstrates quantitative 3D multielemental imaging of geological samples at a considerably higher image-acquisition speed than previously reported, while also offering high spatial resolution and simultaneous multielemental detection. [ABSTRACT FROM AUTHOR]

The distribution of contaminant elements within ecosystems is an environmental concern because of these elements' potential toxicity to animals and plants and their ability to hinder microbial ecosystem services. As with nutrients, contaminants are cycled within and through ecosystems. Elevated atmospheric CO2 generally increases plant productivity and alters nutrient element cycling, but whether CO2 causes similar effects on the cycling of contaminant elements is unknown. Here we show that 11 years of experimental CO2 enrichment in a sandy soil with low organic matter content causes plants to accumulate contaminants in plant biomass, with declines in the extractable contaminant element pools in surface soils. These results indicate that CO2 alters the distribution of contaminant elements in ecosystems, with plant element accumulation and declining soil availability both likely explained by the CO2 stimulation of plant biomass. Our results highlight the interdependence of element cycles and the importance of taking a broad view of the periodic table when the effects of global environmental change on ecosystem biogeochemistry are considered. [ABSTRACT FROM AUTHOR]

Metal speciation data calculated by modeling could give useful information regarding the fate of metals in the rhizospheric environment. However, no comparative study has evaluated the relative accuracy of speciation models in this microenvironment. Consequently, the present study evaluates the reliability of free Cu ion (Cu2+ activity modeled by WHAM 6 and MINEQL+ 4.5 for 18 bulk and 18 rhizospheric soil samples collected in two Canadian forested areas located near industrial facilities. The modeling of Cu speciation was performed on water extracts using pH, dissolved organic carbon (DOC), major ions, and total dissolved Al, Ca, Cu, Mg, and Zn concentrations as input data. Four scenarios representing the composition of dissolved organic substances using fulvic, humic, and acetic acids were derived from the literature and used in the modeling exercise. Different scenarios were used to contrast soil components (rhizosphere vs bulk) and soil pH levels (acidic vs neutral to alkaline). Reference Cu2+ activity values measured by an ion-selective electrode varied between 0.39 and 41 nM. The model MINEQL+ 4.5 provided good predictions of Cu2+ activities [root-mean-square residual (RMSR) = 0.37], while predictions from WHAM 6 were poor (RMSR = 1.74) because they overestimated Cu complexation with DOC. Modeling with WHAM 6 could be improved by adjusting the proportion of inert DOC and the composition of DOC (RMSR = 0.94), but it remained weaker than predictions with MINEQL+ 4.5. These results suggested that the discrepancies between speciation models were attributed to differences in the binding capacity of humic substances with Cu, where WHAM 6 appeared to be too aggressive. Therefore, we concluded that chemical interactions occurring between Cu and DOC were key factors for an accurate simulation of Cu speciation, especially in rhizospheric forest soils, where high variation of the DOC concentration and composition are observed. [ABSTRACT FROM AUTHOR]

Knowledge of trace metal speciation in soil pore waters is important in addressing metal bioavailability and risk assessment of contaminated soils. Numerous analytical methods have been utilized for determining trace metal speciation in aqueous environmental matrixes; however, most of these methods suffer from significant interferences. The Donnan dialysis membrane technique minimizes these interferences and has been used in this study to determine free Zn[sup 2+], Cd[sup 2+], Cu[sup 2+], and Pb[sup 2+] activities in pore waters from 15 agricultural and 12 long-term contaminated soils. The soils vary widely in their origin, pH, organic carbon content, and total metal concentrations. Pore water pM[sup 2+] activities also covered a wide range and were controlled by soil pH and total metal concentrations. For the agricultural soils, most of the free metal activities were below detection limit, apart from Zn[sup 2+] for which the fraction of free Zn[sup 2+] in soluble Zn ranged from 2.3 to 87% (mean 43%). Five of the agricultural soils had detectable free Cd[sup 2+] with fractions of free metal ranging from 59 to 102% (mean 75%). For the contaminated soils with detectable free metal concentrations, the fraction of free metal as a percentage of soluble metal varied from 9.9 to 97% (mean 50%) for Zn[sup 2+], from 22 to 86% (mean 49%) for Cd[sup 2+], from 0.4 to 32.1% (mean 5%) for Cu[sup 2+], and from 2.9 to 48.8% (mean 20.1%)for Pb[sup 2+]. For the contaminated soils, the equilibrium speciation programs GEOCHEM and WHAM Model VI provided reasonable estimates of free Zn[sup 2+] fractions in comparison to the measured fractions (R[sup 2] ∼ 0.7), while estimates of free Cd[sup 2+] fractions were less agreeable (R[sup 2] ∼ 0.5). The models generally predicted stronger binding of Cu[sup 2+] to DOC and hence lower fractions of free Cu[sup 2+] as compared with the observed fractions. The binding of Cu[sup 2+] and Pb[sup 2+] to DOC predicted by WHAM Model VI was... [ABSTRACT FROM AUTHOR]

Quantifies and characterizes trace metal contamination in selected soils and sediments collected from Toronto, Ontario. Use of modified Community Bureau of Reference sequential extraction procedure; Redistribution of cadmium and zinc during the extraction; Metal partitioning behavior; Association of copper and lead with oxidizable organic matter.

Presents details of an analytical approach for the ultratrace qualitative and quantitative determination of eight selected sulfonylureas in selected soil samples. Acceptance criteria for determinations under quantitative and qualitative ion spray selected reaction monitoring (SRM) LC/MS conditions.

Discusses an attempt to use the laser multiphoton ionization method for analysis of trace aromatic compounds on the surface of environmental (soils) and artificial (silica) samples. Composition of measurement setup; Testing of technique for detection of pyrene deposited on moist fine-powdered samples.