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Abstract: Although several studies have used bogs in order to reconstruct paleoclimatic conditions and the historical trends of pollutants, scientific literature is still rather controversial about the role of ombrotrophic bogs as reliable record of past environmental changes. Consequently, understanding whether all vegetational and climatic “information” are effectively preserved in peat deposits during humification becomes an essential aspect to be tested before using bogs as natural archives. The present work focuses on stable isotopic ratios, i.e., 13C/12C (δ13C), 15N/14N (δ15N) and 18O/16O (δ18O), and is based on the assumption that, if bogs are consistent archives of environmental changes, these types of “information” should be recorded also into humic acids (HA), i.e. the fraction of peat more recalcitrant and refractory to degradation. Thus, an 81-cm long peat core, covering the last 2000years, was collected from the Etang de la Gruère bog (Jura Mountains, Switzerland), cut into 3cm slices, and HA were isolated from each age dated layer. Stable isotopic ratios (δ13C, δ15N and δ18O) were then determined in bulk peat and corresponding HA samples. An increase in the humification degree and a decrease of the C/N ratio were observed along the profile. The δ13C of both peat and HA showed a significantly similar trend with depth (p =0.0001), and the same significant correlation was observed for the δ15N (p <0.0001). Also the ratio between δ13C and δ15N closely resembled the C/N ratio observed in the peat and in HA (p <0.0001), thus underlining that the trend of these isotopic ratios is preserved along the studied bog profile. Consequently, our data seem to support both the role of HA as recalcitrant, stable molecules with a long-term residence time, and the potential of ombrotrophic bogs to be used as “archives” of vegetational changes occurring (at least) in the last 2000years. Although a certain relationship (p <0.05) between peat and corresponding HA was found also for δ18O, our data did not allow the solving of the issue of its reliability as paleoenvironmental proxy. [Copyright &y& Elsevier]

Sphagnum peat has been found to efficiently remove heavy metals, oil, detergents, dyes, pesticides and nutrients from contaminated waters since its major constituents, i.e., unesterified polyuronic acids, cellulose, and fulvic and humic acids (HA), show functional groups (e.g., alcohols, aldehydes, carboxylic acids, ketones and phenolic hydroxides) which may adsorb pollutant species. The influence of the extractant on the analytical characteristics of HA is an old but still open topic that should be studied in relation to the nature of the matrix from which they originate. While a number of works have been published on the effects of different reagents on the extraction yields and structural properties of HA from soils, relatively little attention has been devoted to peat HA. In this work, the contents of some major and trace elements (As, Ca, Cr, K, Mn, Sr, and Ti) in five Sphagnum-peat samples and in their corresponding HA fractions isolated using three common extractant solutions, i.e., 0.5M NaOH, 0.1M Na4P2O7, and 0.5M NaOH+0.1M Na4P2O7, where investigated by X-ray fluorescence spectroscopy. In general, Cr, Mn, and Ti concentrations of bulk peat samples were higher than those of the corresponding HA fractions regardless of the extractant used. Arsenic, Ca, K, and Sr concentrations in the HA fractions were affected by the extraction procedure, although at different extents depending on the extractant utilized. In particular, compared to both NaOH and NaOH+Na4P2O7, the Na4P2O7 extractant yielded HA generally richer in As, Ca, K, and Sr, and poorer in Ti. These results may be related to both the nature of each HA fraction and the physical and chemical form of each element supplied to the studied bog via atmospheric deposition. [Copyright &y& Elsevier]

An ombrotrophic peat core was collected in 2005 from Etang de la Gruère, Jura Mountains, Switzerland. The concentrations of nine among the U.S. Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs) (i.e., acenaphthene, phenanthrene, fluorene, pyrene, fluoranthene, benzo[ jbk]fluoranthene, benzo[ a]pyrene, benzo[ ghi]perylene, and indeno[1,2,3- cd]pyrene) were determined in both bulk peat and corresponding humic acids (HA) samples by gas chromatography equipped with a mass spectrometry detector (GC-MS). The maximum PAHs concentrations in peat (around 1,250 μg Σ PAHs kg−1 dry matter) were found at 28–30 cm of depth, which correspond to ca. 1920–1930, when coal inputs to Switzerland reached their maximum level. Amongst the nine PAHs analyzed in the peat samples, pyrene (Pyr) was the predominant species, accounting for ca. 20–100% of the total PAHs throughout the profile. In the HA fraction, that represents 24.7% (average value) of the bulk peat, only phenanthrene (Phe), and sporadically Pyr and fluoranthene (Fth), were detected. In particular, HA showed Phe concentrations that were ten–150 times higher than corresponding bulk peat samples, thus suggesting its preservation against biodegradation due to the incorporation into HA molecules. [ABSTRACT FROM AUTHOR]

Abstract: Scientific results about the role of peatlands as sink or source of bromine are rather antithetic. Although several attempts have been performed to correlate Br content and peat decomposition/humification, the role of humic acids (HAs) as possible sink of this element has not been previously investigated. Two peat cores (2H and 2T), collected from the ombrotrophic bog Etang de la Gruère (Switzerland), were divided in several slices from which humic acids were successively extracted. Bromine content was determined in both peat and corresponding HAs samples using an Energy-dispersive miniprobe X-ray fluorescence multielement analysis (EMMA-XRF). Data show a greater “affinity” of Br for HAs rather than for corresponding bulk peat samples, especially in the first 24 cm of depth where Br concentration in HAs is 3.5 times higher than the one in peat; in particular, approximately 40% (average value) of the total Br in peat is stably incorporated into HAs molecules. Further, the observed correlation between the Br content in HAs and the Pb enrichment factor in peat, especially in the upper part of both profiles, suggests a possible role of HAs as geochemical sink of Br atmospheric deposition. Consequently, humification processes occurring in peat could promote Br accumulation in HAs, thus reflecting the deposition rate of this trace element. [Copyright &y& Elsevier]

Abstract: Among several extractants used to isolate humic acids (HA) from terrestrial environments, sodium hydroxide (NaOH) and sodium pyrophosphate (Na4P2O7) are the most utilized. In order to evaluate the influence of these different extractant solutions on the HA quality and on their trace elements content, HA were isolated from five Sphagnum-peat samples using three different solutions: (a) 0.5M NaOH; (b) 0.1M Na4P2O7; (c) 0.5M NaOH+0.1M Na4P2O7. The obtained HA have been analyzed with respect to ash content, elemental composition, main atomic ratios and characterized by FT-IR and total luminescence (TL) spectroscopies. In addition, both raw peat and HA have been analyzed using X-ray fluorescence in order to determine the Br, Cu, Fe, Ni, Pb and Zn contents. Results showed that HA extracted with NaOH and NaOH+Na4P2O7 are quite similar with respect to ash, elemental contents and spectroscopic characteristics, while Na4P2O7 solution, which in general reduces the extraction yield, seems to affect the nature of HA, featuring a more complex and aromatic character. With respect to the contents in the corresponding raw peat samples, the HA fractions were richer in Br, Cu and Ni, regardless of the extractant used, and poorer in Fe, Pb and Zn. Further, Br, Cu, Ni and Zn were more concentrated in HA extracted with Na4P2O7 than in those extracted with NaOH and NaOH+Na4P2O7, probably because of the greater affinity of these elements for these more aromatic humic molecules. [Copyright &y& Elsevier]

Abstract: An ombrotrophic peat core (10×10×81 cm) was collected from Etang de la Gruère (Switzerland) and divided in 27 slices of 3 cm. Humic acids (HAs) were extracted from each slice after freeze-drying and fine milling. All raw peat and HA samples were analyzed using Energy-dispersive miniprobe X-ray fluorescence multielement analyser (EMMA-XRF), fluorescence spectroscopy and Low Background γ-spectrometry (LB γ-spec). The abundance and distribution of major and trace elements and radionuclides were measured in raw peat and corresponding HAs to possibly evaluate their affinity for organic ligands and establish which organic fraction might affect their behaviour along the profile. Raw peat samples show higher concentrations of Fe, Mn, Pb, Sr, Ti and Ca in comparison to the corresponding HAs, while Cu is more abundant in HAs. Zinc presents greater concentrations in raw peat in the first 24 cm of depth. All elements, with the exception of Fe, seem to be bound stably to HAs, although at different extent. The activity of 241Am is limited to the raw peat of a specific section of the profile, while that of 137Cs is recorded both in HAs and raw peat, even below the depth one would expect, suggesting the scarce mobility of the former and a different impact of these radionuclides on the environment. [Copyright &y& Elsevier]

Abstract: A peat core (10×10×81cm) removed from Etang de la Gruère (Switzerland) was divided into 27 slices of 3cm and the peat samples were freeze-dried and milled very finely. Humic acids (HA) were extracted from each slice. Both raw peat and HA were analyzed with respect to ash content, moisture and elemental (C, H, N, and S) analysis. In addition, they were analyzed using Fourier transform infrared spectroscopy (FT-IR) and UV–Vis spectroscopy (E 4/E 6 ratio). Physical and chemical properties of the peat core appear to show different conditions along the profile; in fact, these data could indicate the presence of 3 distinct zones in the bog: (i) an acrotelm, or zone of active decay, which may be oxygenated, depending on the season, (ii) a catotelm, which is always anoxic, and where only a very slow and partial organic matter decomposition is possible, and (iii) a “transitional” layer, in which complex interactions between organic and inorganic compounds most possibly happen. E 4/E 6 trend and FT-IR spectra on purified HA appear to confirm this hypothesis and underline different stages of humification of organic matter along the profile showing a greater degree of aromatic condensation in the deeper horizons than in the surface layer. [Copyright &y& Elsevier]