Applied Geochemistry (v.16, #2)

Regional distribution of Al, B, Ba, Ca, K, La, Mg, Mn, Na, P, Rb, Si, Sr, Th, U and Y in terrestrial moss within a 188,000 km2 area of the central Barents region: influence of geology, seaspray and human activity by Patrice de Caritat; Clemens Reimann; Igor Bogatyrev; Viktor Chekushin; Tor Erik Finne; Jo H. Halleraker; Galina Kashulina; Heikki Niskavaara; Vladimir Pavlov; Matti Äyräs (137-159).
Five hundred and ninety-eight samples of terrestrial moss (Hylocomium splendens and Pleurozium schreberi) collected from a 188,000 km2 area of the central Barents region (NE Norway, N Finland, NW Russia) were analysed by ICP-AES and ICP-MS. Analytical results for Al, B, Ba, Ca, K, La, Mg, Mn, Na, P, Rb, Si, Sr, Th, U and Y concentrations are reported here. Graphical methods of data analysis, such as geochemical maps, cumulative frequency diagrams, boxplots and scatterplots, are used to interpret the origin of the patterns for these elements. None of the elements reported here are emitted in significant amounts from the smelting industry on the Kola Peninsula. Despite the conventional view that moss chemistry reflects atmospheric element input, the nature of the underlying mineral substrate (regolith or bedrock) is found to have a considerable influence on moss composition for several elements. This influence of the chemistry of the mineral substrate can take place in a variety of ways. (1) It can be completely natural, reflecting the ability of higher plants to take up elements from deep soil horizons and shed them with litterfall onto the surface. (2) It can result from naturally increased soil dust input where vegetation is scarce due to harsh climatic conditions for instance. Alternatively, substrate influence can be enhanced by human activity, such as open-cast mining, creation of ‘technogenic deserts’, or handling, transport and storage of ore and ore products, all of which magnify the natural elemental flux from bedrock to ground vegetation. Seaspray is another natural process affecting moss composition in the area (Mg, Na), and this is most visible in the Norwegian part of the study area. Presence or absence of some plant species, e.g., lichens, seems to influence moss chemistry. This is shown by the low concentrations of B or K in moss on the Finnish and Norwegian side of the (fenced) border with Russia, contrasting with high concentrations on the other side (intensive reindeer husbandry west of the border has selectively depleted the lichen population).

Thermodynamics of ice polymorphs and ‘ice-like’ water in hydrates and hydroxides by Lionel Mercury; Philippe Vieillard; Yves Tardy (161-181).
Thermodynamic properties of water, in various families of hydroxides, oxihydroxides and hydrates (chlorides, chlorates, sulfates and sulfites …), have been calculated by using a large number of data available in the literature. A phase diagram of water has been used to find the first complete set of thermodynamic properties at 298 K, 1 bar of 8 ice polymorphs, from Ih (hexagonal ice, the common polymorph) to IX (very low temperature and high pressure polymorph). These results are used to illustrate the concept of ‘ice-like water’ available for a very large number of hydrated phases (noted X.H2O) in which water is attached to the corresponding anhydrous substrate (noted X) within a large spectrum of different enthalpies (Δ f H°) or Gibbs free energies (Δ f G°), but within a relatively small range of others properties. Heat capacity (Cp°), entropy (S°), and volume (V°) of hydration water (X.H2O−X=H2O) appeared to be very close to those characterizing ice polymorphs such as ice II or ice VIII. This concept allows the authors to propose a classification of minerals in terms of affinity for water and to predict the relative stability of hydrated and dehydrated phases under climatic variations.

Volatile organic acids and microbial processes in the Yegua formation, east-central Texas by Joyanto Routh; Ethan L. Grossman; Glenn A. Ulrich; Joseph M. Suflita (183-195).
Geochemical and microbiological evidence indicates that viable microorganisms produce and consume volatile organic acids (VOA) in the Yegua formation. Acetic and propionic acid concentrations in mudstones range from 200 to 1270 and 20 to 38 nmol·gdw−1 respectively, whereas concentrations in sands are 50–200 and less than 20 nmol·gdw−1. VOA concentrations in sediments and in laboratory incubations suggest net production of VOAs by microorganisms in mudstones, and net consumption of VOAs by SO4 reducing bacteria (SRB) in sands. Notably, SRB activity is mostly confined to aquifer sands.Vertical diffusion and advection were modeled to estimate acetic acid transport from aquitard to aquifer. Assuming that SRB completely respire the acetic acid transported into the aquifer (3.2 μmol·l−1·m·a−1), the CO2 production rate in the aquifer sands is 5.3 μmol·l−1·a−1. This slow mineralization rate of in situ organic matter is within the range for deep aquifers, and probably accounts for the long-term survival of microorganisms in oligotrophic environments. Finally, the microbial communities in Yegua sediments appear to exhibit a loose commensalism, with microorganisms in aquitards providing VOAs for respiratory processes (i.e., SO4 reduction) in aquifers.

Isotopic effects on inorganic carbon in a tropical river caused by caustic discharges from bauxite processing by J.E. Andrews; A.M. Greenaway; P.F. Dennis; D.A. Barnes-Leslie (197-206).
Stable C isotope compositions of dissolved inorganic C (DIC) and carbonate sediment in a Jamaican river (Rio Cobre), are used as natural tracers of accidental spillage of bauxite processing liquor and waste water. Bauxite processing produces highly caustic (OH and CO2− 3) liquor and wash waters. These hydroxide-rich waters absorb atmospheric CO2 that is isotopically fractionated resulting in very negative carbonate δ13C and δ18O values. Accidental spillage of these liquors into rivers causes rapid precipitation of CaCO3 as a fine-grained suspension (‘whiting’) and subsequent deposition as calcite sediment. At the time of DIC sampling ‘whiting’ was not evident; however, δ13CDIC values at sites with a history of contamination were about 2‰ more negative than ambient values. The history of bauxite processing spillages is recorded in the δ13C values of carbonate riverbed sediments. At sites known to be impacted, particulate carbonate samples have δ13C values between −11.2 and −14.2‰; values that are between 1 and 4‰ more negative than the predicted ambient δ13C value. Similarly, δ18O values of carbonate sediments at impacted sites are on average 2‰ more negative than those from sites above and below them, supporting the interpretation that the ‘whiting events’ form precipitates with isotopically negative values. Contamination is quite localized because carbonate sediments downstream of impacted sites show no evidence of anomalous isotope values. This suggests that the particulate carbonate is either flushed or re-dissolves, and is diluted downstream. The carbonate ‘whitings’ are thus highly visual but relatively benign, although the associated pH and dissolved Al3+ and Na+ flushes might have more serious impacts on the river environment.

The environment surrounding Palmerton, Pennsylvania is contaminated with Pb arising from primary Zn smelting and a process involving Zn recovery from electric arc steel furnace dusts. Lead isotope systematics have been used to distinguish primary Zn smelting Pb (206Pb/204Pb∼18.4–18.5) from electric arc furnace dust lead (206Pb/204Pb∼19.0–19.1). Primary Zn smelting is the dominant source of Pb in O2 horizon soils from undisturbed near-Palmerton locations, which contain up to 3570 ppm Pb and 782 ppm Cd. Soils from undeveloped near-Palmerton locations also exhibit unusually elevated concentrations of other sphalerite-derived chalcophilic elements (Se, Ag, In, Sb, Te, Au, Hg, Tl and Bi); indium concentrations of up to 17.0 ppm are observed therein. Residential soils and dusts from Palmerton contain Pb which is largely explainable via mixing of Pb from primary Zn smelting and electric arc furnace dusts. Approximately 80% of the Pb in airborne particulate matter sampled at Palmerton in 1991 is derived from electric arc furnace dusts, and atmospheric enrichment factors for Cu, Sb, Pb, and Bi are observed which confirm this major source contribution. Residential samples from a control location contain Pb which is less radiogenic than is found in Palmerton, and exhibit no unusual elevation in sphalerite elements. Lead source discrimination in the Palmerton environment via Pb isotopic and elemental constituents approaches result in parallel conclusions.

Standard reference water samples for rare earth element determinations by P.L. Verplanck; R.C. Antweiler; D.K. Nordstrom; H.E. Taylor (231-244).
Standard reference water samples (SRWS) were collected from two mine sites, one near Ophir, CO, USA and the other near Redding, CA, USA. The samples were filtered, preserved, and analyzed for rare earth element (REE) concentrations (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) by inductively coupled plasma-mass spectrometry (ICP-MS). These two samples were acid mine waters with elevated concentrations of REEs (0.45–161 μg/l). Seventeen international laboratories participated in a ‘round-robin’ chemical analysis program, which made it possible to evaluate the data by robust statistical procedures that are insensitive to outliers. The resulting most probable values are reported. Ten to 15 of the participants also reported values for Ba, Y, and Sc. Field parameters, major ion, and other trace element concentrations, not subject to statistical evaluation, are provided.

Lichen (n=12) and moss (n=6) species from a remote region of northern Canada have remarkably similar multi-element patterns suggesting they are non-specific accumulators of metals under existing conditions. Within individual species the concentration of many metals analyzed range over an order of magnitude. Many elements have a positive correlation with multi-element (n=48) and REE (rare earth element) totals. Others, such as Cd, K, and Zn have relatively consistent concentrations across all lichen and moss species, and across all sampling sites, indicating different accumulation and/or retention processes. Lichens and mosses have REE concentrations 1–3 orders of magnitude less than those of the average upper continental crust (UCC) but yield identical patterns. The correlation of other poorly soluble elements and key elemental ratios in lichen and moss are also similar to UCC and modern river sediment values. Metals including Sc, V, Cr, Fe, Co, Ga, Y, Hf, W, Pb, Th, and U show strong positive correlations with REE in lichen and moss. Rare earth elements may be useful as reference elements in environmental studies because of transport in the particulate phase, lack of significant anthropogenic sources, coherent group geochemistry, generally robust concentrations, and upper crustal signatures. Further, the REE may be helpful in identifying particulate deposition related to anthropogenic activities and enrichment of other elements by biogenic processes. The multi-element compositions of vascular plants (leaves and twigs) are fundamentally different from those of lichen and moss, lack correlation with REE, and are extremely enriched for many elements (100–1000× average upper continental crust) relative to the REE; perhaps because of limited REE solubility and transport via root systems. Enrichment factors for most metals of environmental concern are low; Pb is elevated but may be an artifact of low concentrations in local bedrock. Trace metal concentrations in lichen and moss at Otter Lake are similar to those measured across the Northwest Territories over 25 a ago.