G. Márquez

Lichens as biomonitors for the determination of polycyclic aromatic hydrocarbons (PAHs) in Caracas Valley, Venezuela

Biomonitoring of PAH air pollution using lichens was carried out. Sixteen PAHs were studied in 11 locations along the valley of Caracas (Venezuela). The results of this work indicate that 14 of the 16 analysed PAHs were highly accumulated into the lichen thalli of Pyxine coralligera Malme. PAH levels in the samples revealed that the several volatile PAHs (naphthalene, acenaphtylene, acenaphtene, and fluoranthene) have the highest levels in the majority of the studied locations. The fluoranthene/pyrene and phenantrene/antracene ratios suggested that the major sources of PAHs are anthropogenic, mainly associated with gasoline and diesel combustion (pyrolytic) and unburnt oil derivates (petrogenic). The total PAH concentrations obtained in the present study were in the range of 0.24 to 9.08 µg/g, similar to those reported by other works in European and Asian cities.

Petrography, biomarker composition, mineralogy, inorganic geochemistry and paleodepositional environment of coals from La Ballesta mine, Peñarroya Basin, Spain

PurposeThe purpose of this work is to study coal samples from various exposed seams of the La Ballesta mine, at the southeastern edge of the Peñarroya-Belmez-Espiel coalfield, southwestern Spain. Shaly seat- and caprocks were also investigated.MethodPetrographic, palynological, and biomarker analyses were carried out. The major elements were determined by X-ray fluorescence (XRF). The trace elements were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS).ResultsThe Pennsylvanian (Westphalian)-age, high volatile bituminous coal studied is a humic coal with vitrinite concentrations of over 86% on a minerals-free basis and low amounts of liptinite and inertinite. The coals have a relatively higher volatile matter yields than the bituminous coals in western areas of the basin with similar vitrinite reflectance values and present both a dark and a light variety of vitrinite. The dark variety is more abundant in the low ash coals considered to have been formed in nearby lacustrine settings. The mineral assemblage of the coals and non-coal (roof and floor) rocks from the La Ballesta mine is dominated by quartz, kaolinite and illite, with minor to trace proportions of epigenetic carbonates, anatase, and K-feldspar, among others.ConclusionsConcentrations of B and B/Be ratios, along with other data, suggest that the La Ballesta coals may have originated from topogenous mires that developed next to lacustrine settings. Coal seams 9, 9bis, and 14 were probably more restricted systems than coaly shale 15, the latter corresponding to swamps associated with alluvial and floodplain environments. Abnormally high concentrations of trace elements such as Li, Rb, Cs, Sc, V and Cr might be explained by the input of detrital minerals into the Peñarroya Basin from the outcropping Precambrian and Lower Palaeozoic rocks to the northeast. In this regard, elemental ratios such as Al2O3/TiO2 for the samples suggest that the modes of occurrence of the trace elements, and the minerals, in La Ballesta coals and non-coal rocks are to be mainly attributed to detrital input from felsic to intermediate metamorphic rocks.ResumenObjetivoEl objetivo de este trabajo es estudiar una serie de muestras de carbón de varios mantos aflorantes de la mina La Ballesta, en el margen suroriental de la cuenca minera de Peñarroya-Belmez-Espiel, suroeste de España. Las correspondientes lutitas infra- y suprayacentes también fueron investigadas.MétodosAnálisis petrográficos, palinológicos y de biomarcadores fueron realizados. Los elementos mayoritarios se analizaron por fluorescencia de rayos X (XRF). Los elementos traza se analizaron por espectrometría de masas con plasma acoplado inductivamente (ICP-MS).ResultadosEl carbón bituminoso alto volátil de edad Pensilvánica (Westfaliense), extraído en la zona de La Ballesta, es un carbón húmico con concentraciones de vitrinita de más del 86% en base libre de materia mineral y bajas cantidades de liptinita e inertinita. Estos carbones tienen una proporción de materia volátil relativamente mayor que en el caso de los carbones bituminosos de las parte occidental de la cuenca en estudio, pero poseen similares valores de reflectancia de la vitrinita, y presentan una variedad oscura y otra clara de vitrinita. La variedad oscura es más abundante en los carbones con bajo contenido en ceniza que se han formado en las cercanías de un medio lacustre. La mineralogía de carbones y lutitas (infra- y suprayacentes) de la mina La Ballesta está dominada por el cuarzo, caolinita e illita, con proporciones menores a trazas de carbonatos epigenéticos, anatasa y feldespato potásico, entre otros.ConclusionesLas concentraciones de B y ratios B/Be, entre otros datos, sugieren que los carbones de La Ballesta se habrían formado a partir de cenagales que se desarrollaron junto a lagos. Los carbones 9, 9bis, and 14 se relacionan probablemente con sistemas más restringidos que en el caso de la lutita carbonosa 15; correspondiendo esta última con pantanos asociados con ambientes aluviales y llanuras de inundación. Unos valores anormalmente altos de las concentraciones de elementos traza tales como Li, Rb, Cs, Sc, V y Cr se pueden explicar por el aporte de minerales detríticos en la Cuenca Belmez-Espiel Peñarroya procedentes del afloramiento hacia el noreste de rocas de edad Precámbrica y Paleozoica temprana. A este respecto, relaciones elementales tales como Al2O3/TiO2 sugieren que el origen de los elementos traza y las fases minerales, en carbones y lutitas de La Ballesta, pueden ser principalmente atribuido al aporte de detritos derivados de rocas metamórficas de tipo félsico a intermedio.