Leaching of polycyclic aromatic hydrocarbons (PAHs) from coal dumps reclaimed with apple trees: a mechanistic insight.

Polycyclic aromatic hydrocarbons (PAHs) have been identified as compounds that can be incorporated to run-off waters or to aquifers becoming a real threat not only to aquatic organisms but also to humans due to its carcinogenic and mutagenic activity. This work studies the presence of PAHs in a coal dump pile located in the north of Spain (Asturias), downhill a spoil pile of a cinabrium mine. This unique site gives the opportunity to assess whether acid waters have more potential to leach PAHs than normal rainwater (acidified when it gets in contact with coal spoil). The distribution of PAHs and methyl PAHs has shown that their abundance is higher in the path of acid waters which could be caused by the ability of acid water to break bonds of coal macromolecules. This chemical reaction liberates PAHs of less molecular weight that can be detected by GC-MS. Moreover, less soluble PAHs are concentrated on the acid water circulation area and more soluble PAHs more leached by acid water that rainwater, which indicates that PAHs dissolve more in acid waters than in normal rainwater. In addition, this coal spoil pile has been reclaimed with apple trees to make cider for human consumption. Up to 152 different compounds were identified in the tree samples, but neither PAHs nor methyl PAHs were found, pointing to a possible retention of the PAHs in the roots zone. Apple trees in the acid waters path show more concentration in waxes and flavour compounds, indicating a more mature apple.

Multivariate study of trace element distribution in the geological record of Roñanzas Peat Bog (Asturias, N. Spain). Paleoenvironmental evolution and human activities over the last 8000 calyr BP.

Trace element concentrations in the Roñanzas peat bog record reveal a contribution of natural processes but the influence of anthropogenic factors predominates in the last two millenniums, particularly aerosol deposition linked to mining and industrial activities in northern Spain. We observed that the Roñanzas record can be considered a preserved environment, suitable to search for local (<50 km), regional (50-150 km) and/or long-distance human activity fingerprinting, specifically that related to the deposition of heavy metals such as Pb, Zn and Hg. We also carried out a multivariate statistical study in order to clarify the geochemical behavior of trace and major elements. Our study design represents a novel approach to assign natural vs. human contributions in peatlands. Therefore, synergies obtained by the simultaneous study of multivariate statistics and enrichment factors allow robust conclusions about paleoenvironmental evolution and human activities. Anthropogenic influence has also been reported in similar records in other parts of Europe, thereby suggesting large-scale sources for atmospheric pollution. However, here we revealed remarkable particularities, such as the association of Cd, Zn and Pb, mainly linked to regional and local factors (mining and more recently the metallurgical industry), whereas we propose that the occurrence of Hg is associated with a combination of regional factors and global atmospheric pollution.

Geochemical evolution of amino acids in dentine of Pleistocene bears.

A linear correlation was established between aspartic acid racemization ratio from cave bear dentine collagen and absolute dating. The high correlation coefficient obtained allowed age calculation through amino acid racemization. Aspartic acid and glutamic acid racemization kinetics have also been explored in dentine from a North American black bear (Ursus americanus Pallas). Three sample sets were prepared for kinetic heating experiments in nitrogen atmosphere: one water soaked, one with a water-saturated nitrogen atmosphere, and one without any moisture. It was possible to show that the presence of water is a factor controlling amino acid racemization rate. The aspartic acid in a heating experiment at 105 degrees C shows an "apparent kinetics reversal" which can be explained by a progressive hydrolysis of amino acid chains (proteins and polypeptides). Because of the low potential of collagen preservation over long periods of time, the apparent kinetics reversal phenomenon will not affect the dating of old material where no traces of collagen remain. An apparent kinetics reversal was not observed in glutamic acid, which racemizates more slowly.

Bioremediation of diesel-contaminated soils: evaluation of potential in situ techniques by study of bacterial degradation.

The development of a simple laboratory methodology allows the implementation of in situ bioremediation of polluted soils with diesel fuel. In this investigation microbiological and chemical analyses and a suitable bioreactor design, were very useful for suggesting the best ways to improve biodegradation extents in a diesel-enriched soil. Biostimulation with inorganic nitrogen and phosphorus produced the best results in a simple bioreactor, with biodegradation extents higher than 90% after 45 days. Also, the addition of activated sludge from a domestic wastewater plant increased the degradation rate to a great extent. In both cases, microbiological studies showed the presence of Acinetobacter sp. degrading most of the hydrocarbons. Simultaneously, a diesel fuel release (approximately 400,000 l) was studied. Samples taken in polluted soil and water revealed that bacteria from the genus Acinetobacter were predominant. In plate studies, Acinetobacter colonies produced a whitish substance with the characteristics of a biosurfactant. Remarkably, the presence of this product was evident at the field site, both in the riverbanks and in the physical recovery plant. The study of the similarities between laboratory results and the diesel spill site strongly suggested that natural conditions at the field site allowed the implementation of in situ bioremediation after physical removal of LNAPL (light nonaqueous-phase liquids).