Sulfur Fixation in Wood Mapped by Synchrotron X-ray Studies: Implications for Environmental Archives

• Published in: Environmental science & technology Vol. 43; no. 5; pp. 1310 - 1315
• Main Authors: Fairchild, Ian J, Loader, Neil J, Wynn, Peter M, Frisia, Silvia, Thomas, Peter A, Lageard, Jonathan G. A, Momi, Anna de, Hartland, Adam, Borsato, Andrea, Porta, Nicola La, Susini, Jean
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.03.2009
• Subjects: Abies; Abies - metabolism; Abies alba; Animal, plant and microbial ecology; Applied ecology; Applied sciences; Archives & records; Biological and medical sciences; Cell Wall - chemistry; Characterization of Natural and Affected Environments; Ecotoxicology, biological effects of pollution; Environment; Environmental Pollution; Environmental science; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Models, Statistical; Nutrients; Picea - metabolism; Picea abies; Pollution; Powders; Reproducibility of Results; Resins, Plant - chemistry; Spectrophotometry, Atomic; Sulfur; Sulfur - metabolism; Synchrotrons; Time Factors; Trees - metabolism; Wood; Wood - metabolism; X-Rays; Italy; Europe; Alps; Ecosystem; Trend analysis; Watershed; Air pollution; Oxidation; X ray analysis; Cell wall; Thickening
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es8029297

There is a shortage of archives of sulfur that can be used to investigate industrial or volcanic pollution in terrestrial catchments, but the role of S as a nutrient, coupled with sparse published evidence, suggests that trees are promising targets. We focused on two conifer species (Picea abies (L.) Karst and Abies alba Miller) from an Alpine site in NE Italy. Bulk analyses of Abies demonstrate that S concentrations were higher in the second half of the 20th century but with some high outliers possibly reflecting particulate impurities. X-ray synchrotron analyses confirmed the observed time trend, which is similar to that of a nearby stalagmite, and reflects an atmospheric pollution record mediated by storage in the soil and ecosystem. S and P were found to be localized in the inner cell wall (ca. 2 μm wide), local thickenings of which probably account for some outlying high values of S in synchrotron studies. S occurs as a mixture of oxidation states (0 to +0.5, +2, +5, and +6) which are consistent in space and time. The results indicate that wood older than a few years contains archive-quality S but that robust conclusions require multiple replicate analyses.