Ronald R. Martin

Studies of elemental distributions within discrete coal macerals: Use of secondary ion mass spectrometry and X-ray photoelectron spectroscopy

Abstract Secondary ion mass spectrometry has been used to measure qualitatively the distributions of many trace and minor elements within some well-characterized coal macerals: vitrinite, fusinite and exinite. Complementary information was obtained by using X-ray photoelectron spectroscopy. Within the vitrinite specimens studied, a widely-dispersed largely inorganic aluminosilicate phase was identified, which contained a number of other trace elements. By contrast, within the organic-rich phase of this macerai, titanium was detected in a very even distribution; this suggests that some titanium may be bonded in an organic complex. The fusinite was shown to contain elevated concentrations of calcium, magnesium and fluorine, dispersed over a large portion of the maceral. The high fluorine content could be identified as an organo-fluoro compound using XPS. Exinite was found to contain lower concentrations of most elements, compared to other macerals. The organic composition of this maceral was significantly different from that of surrounding macerals; this could be seen from the enhanced emission of the C 2 H 2 -secondary ion and images of this ion thus clearly outlined the position of such macerals.

Relationships amongst organic matter content, heavy metal concentrations, earthworm activity, and soil microfabric on a sewage sludge disposal site

Abstract From 1973 to 1980, sewage sludge precipitated by three chemical treatment processes (aluminum sulphate, ferric chloride and calcium hydroxide) was applied to replicated plots on a silt loam soil at four different rates. The sludge was contaminated by heavy metals associated with industrial activity in the metropolitan areas from where it was collected. The grass on the plots has been mown regularly from 1973 onwards. Soil and earthworm populations were subjected to analysis in 1989 and 1990. Soil pits were dug and sampled to a depth of 50 cm in four plots receiving the highest rates of the three different types of sewage treatment processes (and a control plot treated through the same period with ammonium nitrate) to determine heavy metal contents and soil organic matter distributions with depth. The earthworm fauna of the plots was almost entirely represented by populations of Lumbricus terrestris L. that were analyzed for abundance and biomass following collection using the formalin expulsion method. Earthworm biomass was higher in sludge treatments than in control plots. Cadmium concentrations in earthworm tissues were correlated with soil Cd concentrations Only worms from Al-sludge treatments had elevated tissue concentrations of Cd. Cadmium distributions in sludgetreated soils were correlated with organic matter distributions in the soil profile (for individual profiles). Intact blocks of soil were removed from soil pits for chemical analysis of the soil microfabric by PIXE (proton induced X-ray emission) and electron micro-probe (EMP). Concentrations of several trace metals on the inner walls of the earthworm channels correlated with those added to the soil via the sludge. Water flow through earthworm burrows lined with fecal material, which had higher metal concentrations than the adjacent soil matrix, could move soluble forms of the elements, thus accelerating leaching of metals into the aquifer from surface-applied sludge.

Time-of-flight secondary ion mass spectrometry analysis of hair from archaeological remains

Hair from four individuals excavated from burial sites in Pacatnamu, Peru from the Moche (450–800 AD) and Lambayeque (900–1100 AD) periods was sectioned longitudinally and analysed with time-of-flight secondary ion mass spectrometry (ToF-SIMS). An attempt was made to distinguish biogenic and diagenetic contributions to the elemental concentrations in the hair samples. Significant contamination was observed to have penetrated the hair samples from the burial environment. Results from the analyses indicate that the burial environment plays an important role in the postmortem variation in elemental content of hair samples. Various elements demonstrated an ability to permeate through the hair matrix over time. In addition, NaCl and what are believed to be aluminosilicates and mineral sulphates, were observed to have accumulated on the surface of the samples. Degradation of the samples was also suspected due to the presence of molecular fragments, possibly resulting from oxidation of the keratin proteins. The results should assist in the identification of reliable elemental signals in the analysis of ancient hair samples and promote caution when considering elements that are abundant in the burial environment.

Mineral Weathering in the Rhizosphere of Forested Soils

ABSTRACT The rhizosphere is a microenvironment enriched in organic matter and generally more acidic than the bulk soil. In this chapter, we submit that mineral weathering and metal fractionation differ in the rhizosphere compared to the bulk soil, a change that could impact on plant nutrition and element toxicity. The objective of the study is to establish the nature of the effect of roots on mineral weathering in the rhizosphere of forested soils based on differences in (1) mineralogical composition and (2) the chemical forms of metals between the rhizosphere and the bulk soil. The study area was located in Rouyn–Noranda (Canada), where samples were collected under Populus tremuloides growing on Luvisolic soils. X-ray diffraction (XRD), time of flight secondary-ion mass spectroscopy (TOF-SIMS) and X-ray absorption near-edge structure (XANES) analyses were performed. The concentrations of Al, Ca, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Ni, Pb, Si and Zn were obtained from an acid ammonium oxalate (AAO) extraction. The XRD results show differences in mineralogical abundance, particularly of chlorite and amphibole, which is interpreted as an increase in mineral weathering in the rhizosphere. It was suggested in the literature that the higher alteration in the rhizosphere could be related to K uptake by roots. However, our results show greater BaCl2-extractable K in the rhizosphere, an observation in opposition to this nutrient-depletion hypothesis. The AAO extraction reveals higher contentrations of Fe and Mn in the rhizosphere. These data support XRD results and suggest the formation of secondary oxides in the rhizosphere through weathering. In turn, the greater abundance of oxides creates absorption sites for trace elements such as Cu and Zn as supported by the AAO extractions. The TOF-SIMS mapping also shows an accumulation of total metals at the soil–root interface. The XANES analysis of Mn further indicates that metals tend to be oxidized in the rhizosphere, whereas they are found in organic forms in the root or as a mixture of both at the soil–root interface. The presence of oxidized forms of Mn in the rhizosphere is in agreement with the results of the AAO extraction. In summary, weathering is shown to be higher in the rhizosphere, favors the formation of oxides, notably Mn oxides and, hence, the retention of trace metals.

Arsenic uptake in orchard trees: implications for dendroanalysis.

The distribution of arsenic in the stems of fruit trees grown in soils exposed to arsenical pesticides has been studied using neutron activation analysis. The results show arsenic to be confined mainly to heartwood near the pith and active xylem tissue in the most recent annual growth rings. These results suggest that dendroanalysis for arsenic in fruit trees will not yield a reliable chronology of arsenic exposure.

SIMS imaging in the study of coal surfaces

Abstract With SIMS imaging of coal macerals it was possible to distinguish organic and inorganic domains. In the study presented here three phases could be identified—an aluminosilicate phase, an organic rich region and a second inorganic phase rich in Ca. The results show that SIMS imaging is a powerful technique for determining in situ element distributions.

Measurement of the activation energy of the low temperature oxidation of coal using secondary ion mass spectrometry

Abstract Accurate determination of the activation energy of the low temperature oxidation of coal provides insights into the mechanism of the reaction. In this paper, secondary ion mass spectrometry (SIMS) has been used to measure the relative surface concentrations of 18 O on coal surfaces oxidized in 18 O 2 at 23, 70 and 90 °C respectively. These results have been used with the Arrhenius equation to estimate the activation energy for the deposition of 18 O at the coal surface, i.e. 47.1 and 82.0 kJmol −1 in the ranges 23–70 °C and 70–90 °C, respectively.

Micro-synchrotron x-ray fluorescence of cadmium-challenged corn roots

Abstract Micro-synchrotron X-ray fluorescence was carried out to examine the metal distribution in cadmium-challenged corn ( Zea mays ) roots. The results suggest that cadmium alters calcium distribution in the root tissue.

Comparison of the distributions of bromine, lead, and zinc in tooth and bone from an ancient Peruvian burial site by X-ray fluorescence

Synchrotron micro X-ray fluorescence was used to study the distribution of selected trace elements (Zn, Pb, and Br) in tooth and bone samples obtained from an individual from a pre-Columbian archaeological site (Cabur) located on the north coast of Peru. The results show that Zn, Pb, and Br are present in both the teeth and bone samples and that the Zn and Pb seem to be confined to similar regions (cementum and periostium), while Br shows a novel distribution with enrichment close to the Haversian canals and (or) in regions that appear to be Ca deficient.Key words: teeth, bone, metals, XRF, Br, Zn, and Pb.

Three-dimensional SIMS imaging of 18O2 oxidized calcium-loaded graphite

Abstract Two-dimensional secondary ion mass spectrometry (SIMS) imaging provides evidence that the catalytic activity of calcium in the gasification of calcium-loaded graphite involves the dissociative chemisorption of oxygen on calcium oxide particles and/or calcium on cation exchange sites to form reactive surface complexes. The work reported here extends the study to three-dimensional imaging. The results confirm the two-dimensional observations.