Juan F. Llamas

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

The development of a simple laboratory methodology allows theimplementation of in situbioremediation of polluted soils with diesel fuel. In thisinvestigation microbiological and chemical analyses and a suitable bioreactor design, were veryuseful for suggesting the best ways to improve biodegradation extents in a diesel-enrichedsoil. Biostimulation with inorganic nitrogen and phosphorus produced the best resultsin 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 degradationrate to a great extent. In both cases, microbiological studies showed the presence ofAcinetobacter sp. degrading most of thehydrocarbons. Simultaneously, a diesel fuel release(approximately 400,000 l) was studied. Samples taken in polluted soil and water revealed thatbacteria from the genus Acinetobacterwere predominant. In plate studies, Acinetobacter coloniesproduced a whitish substance with the characteristics of a biosurfactant. Remarkably, thepresence of this product was evident at the field site, both in the riverbanks and in the physicalrecovery plant. The study of the similarities between laboratory results and the diesel spillsite strongly suggested that natural conditions at the field site allowed the implementationof in situ bioremediation after physical removal of LNAPL (light nonaqueous-phase liquids).

Biodegradation of Oil Tank Bottom Sludge using Microbial Consortia

We present a rationale for the selection of a microbial consortia specifically adapted to degrade toxic components of oil refinery tank bottom sludge (OTBS). Sources such as polluted soils, petrochemical waste, sludge from refinery-wastewater plants, and others were used to obtain a collection of eight microorganisms, which were individually tested and characterized to analyze their degradative capabilities on different hydrocarbon families. After initial experiments using mixtures of these strains, we developed a consortium consisting of four microorganisms (three bacteria and one yeast) selected in the basis of their cometabolic effects, emulsification properties, colonization of oil components, and degradative capabilities. Although the specific contribution each of the former parameters makes is not clearly understood, the activity of the four-member consortium had a strong impact not only on linear alkane degradation (100%), but also on the degradation of cycloalkanes (85%), branched alkanes (44%), and aromatic and sulphur–aromatic compounds (31–55%). The effectiveness of this consortium was significantly superior to that obtained by individual strains, commercial inocula or an undefined mixture of culturable and non-culturable microorganisms obtained from OTBS-polluted soil. However, results were similar when another consortium of four microorganisms, previously isolated in the same OTBS-polluted soil, was assayed.

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 cal yr 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.

Polycyclic Aromatic Hydrocarbons (PAHs) produced in the combustion of fatty acid alkyl esters from different feedstocks: Quantification, statistical analysis and mechanisms of formation

Polycyclic Aromatic Hydrocarbons (PAHs) are pollutants of concern due to their carcinogenic and mutagenic activity. Their emissions are mainly related with the combustion or pyrolysis of the organic matter, such as in fossil fuels combustion. It is important to characterize PAHs in the combustions of biofuels due to their increasing importance in the actual energetic setting. There is a lot of research focused in PAHs emission due to the combustion in diesel engines; but only few of them have analyzed the effect of raw material and type of alcohol used in the transesterification process. Different raw materials (i.e. animal fat, palm, rapeseed, linseed, peanut, coconut, and soybean oils) have been used for obtaining FAME and FAEE. A method for measuring PAHs generated during combustion in a bomb calorimeter has been developed. Combustion was made at different oxygen pressures and the samples were taken from the bomb after each combustion. Samples were extracted and the PAHs amounts formed during combustion were analyzed by GC-MS. This research shows the statistical relationships among the 16 PAHs of concern, biodiesel composition and oxygen pressure during combustion.

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.Graphical Abstract

Organochlorine pesticides in protected areas: El Hito Lake (Cuenca, Central Spain)

BackgroundEl Hito Lake is an ephemeral saline water mass present most of the year as a gypsiferous salt pan that is temporarily flooded during rainy periods, when it becomes a refuge for migratory birds such as flamingos and cranes, among others. It is considered an important hotspot of biodiversity and as such is covered by protection status.PurposeIn order to check the environmental condition of the lake and determine the spatial distribution and source of organochlorine pesticides (OCPs), we performed a detailed soil and sediment sampling campaign with the catchment and dry lake bottom.MethodsWe present the first environmental evaluation of its current state with respect to OCPs: hexachlorobenzene (HCB), hexachlorocyclohexanes (α-, β-, γ- and δ-HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDE and DDD), and cyclodienes (aldrin, dieldrin, endrin, endrin aldehyde, endrin ketone, α-chlordane, γ-chlordane, endosulfan I, endosulfanII, endosulfan sulphate, heptachlor, heptachlor epoxide B and metoxichlor).ResultsSome of the compounds showed concentrations above the soil screening levels (SSLs) for human health and ecosystems: γ-HCH (100 μg/kg), α-HCH (60 μg/kg), endrin (30 μg/kg), aldrin (30 μg/kg) and heptachlor epoxide B (30 μg/kg). Various indices were used to determine the origin of the compounds.ConclusionHistorical uses were interpreted, although there were traces of recent input. Distribution maps of concentration and indices demonstrate a relationship between farming and cropping and the maxima observed, being possible that OCPs have influence in living beings, especially birds.ResumenAntecedentesLa Laguna de El Hito es un humedal salino y efímero que aparece la mayor parte del año como un salar yesífero en el que se acumula agua durante periodos lluviosos y se convierte en refugio de aves migratorias como flamencos y grullas, entre otros. Se considera un lugar de importancia para la biodiversidad y por ello está protegido por diversas directivas.ObjetivosSe realizó una campaña de muestreo de los suelos de la cuenca y de los sedimentos del fondo de la laguna con el objetivo de conocer su estado ambiental y determinar la distribución espacial y el origen de los pesticidas organoclorados (OCP).MétodosSe presenta la primera evaluación del estado actual de la laguna respecto a los OCP: hexaclorobenzeno (HCB), hexaclorociclohexanos (α-, β-, γ- y δ-HCH), diclorodifeniltricloroetano (DDT) y sus metabolitos (DDE y DDD), y los ciclodienos (aldrín, dieldrín, endrín, endrín aldehido, endrín cetona, α-clordano, γ-clordano, endosulfán I, endosulfánII, endosulfán sulfato, heptacloro, heptacloro epóxido B y metoxicloro).ResultadosAlgunos compuestos mostraron concentraciones por encima de los Niveles Genéricos de Referencia (NGR) para la salud humana y los ecosistemas: γ-HCH (100 μg/kg), α-HCH (60 μg/kg), endrín (30 μg/kg), aldrín (30 μg/kg) y heptacloro epóxido B (30 μg/kg). Se emplearon varios índices para determinar el origen de estos compuestos.ConclusionesSe interpretó un uso histórico, aunque en algunos casos con un origen reciente. Los mapas de distribución mostraron la alta correspondencia entre la agricultura y ganadería con máximos observados, siendo posible que los pesticidas tengan influencia nociva en los organismos, especialmente en las aves.