The La Luna/Río Negro(.) Petroleum system at the Urdaneta West Field, lake Maracaibo basin, NW Venezuela: ID basin modelling and secondary oil migration

This paper investigates the timing of hydrocarbon generation in the northern part of the Urdaneta West field in the NW of the Lake Maracaibo Basin, NW Venezuela, based on ID basin modelling at three wells referred to as wells X, Y and Z. Kitchen areas were identified and secondary migration directions were inferred based on analyses of the thermal and burial history of the Upper Cretaceous La Luna Formation source rock and the geochemistry of 20 oil samples from the Río Negro Formation reservoir. Aliphatic hydrocarbons in the oil samples were analysed by gas chromatography - mass spectrometry (GC-MS) while the vanadium- nickel and sulphur contents were determined by energy dispersive X-ray spectrometry and inductively coupled plasma optical emission spectroscopy, respectively. Bulk and molecular characterizations indicated that the oils originated from a marine carbonate source rock containing oil-prone Type II kerogen, consistent with generation by the La Luna Formation. Burial and thermal history modelling in the study area indicated that the La Luna source rock at wells X, Y and Z reached the oil window during the late Eocene, mid-Eocene and early Paleocene respectively. ID model results from the three wells showed that hydrocarbon generation began in the early Eocene. The transformation ratio of the La Luna Formation source rock in the modelled wells reached values of 35%, 98% and 100% by the end of the Eocene. In the Urdaneta West field, two different oil charges appear to have mixed in the Río Negro reservoir. Both oil charges were generated by the La Luna Formation source rock but at different times. A first charge of less mature oil occurred in the middle-late Eocene (Phase 1 generation), and a second, more mature oil charge took place in the Miocene - Quaternary (Phase 2 generation). The kitchen area for the first oil charge is inferred to have been located to the north and NE of Urdaneta West; that for the second oil charge to the south of the field. This migration model is supported by observed variations in the geochemical compositions of the oil samples analysed from different wells in the Urdaneta West field.J.G. Diaz acknowledges the support of the PDVSA Western Exploration Project Management and the University of Zulia. The authors are grateful to Iván Chirino and Patricia Marín for their scientific assistance. We are also grateful to the JPG referees (Karla Quintero-Bonilla, Katya Reategui and anonymous) whose comments helped to improve the original version of this manuscript. Carlos Boente obtained a post-doctoral contract within the program PAIDI 2020 (Ref 707 DOC 01097), co-financed by the Junta de Andalucía (Andalusian Government) and the EU

Nanoscale zero-valent iron-assisted soil washing for the removal of potentially toxic elements

The present study focuses on soil washing enhancement via soil pretreatment with nanoscale zero-valent iron (nZVI) for the remediation of potentially toxic elements. To this end, soil polluted with As, Cu, Hg, Pb and Sb was partitioned into various grain sizes (500?2000, 125?500 and <125??m). The fractions were pretreated with nZVI and subsequently subjected, according to grain size, to Wet-High Intensity Magnetic Separation (WHIMS) or hydrocycloning. The results were compared with those obtained in the absence of nanoparticles. An exhaustive characterization of the magnetic signal of the nanoparticles was done. This provided valuable information regarding potentially toxic elements (PTEs) fate, and allowed a metallurgical accounting correction considering the dilution effects caused by nanoparticle addition. As a result, remarkable recovery yields were obtained for Cu, Pb and Sb, which concentrated with the nZVI in the magnetically separated fraction (WHIMS tests) and underflow (hydrocyclone tests). In contrast, Hg, concentrated in the non-magnetic fraction and overflow respectively, while the behavior of As was unaltered by the nZVI pretreatment. All things considered, the addition of nZVI enhanced the efficiency of soil washing, particularly for larger fractions (125?2000??m). The proposed methodology lays the foundations for nanoparticle utilization in soil washing operations.This work was supported by Project CTM2016-75894-P (MINECO). Carlos Boente obtained a grant from the “Formación del Profesorado Universitario” program, financed by the “Ministerio de Educación, Cultura y Deporte de España”. The authors thank the “Servicio Cientifico-Técnico de Medidas Magnéticas” of the University of Oviedo

A holistic methodology to study geochemical and geomorphological control of the distribution of potentially toxic elements in soil

Control of Potentially Toxic Elements (PTEs) in soil-polluted areas is needed to address the potential risk that pollution poses to public health and the environment. This study describes an innovative holistic methodology to assess the distribution of PTEs. It is based on the application of multi-variate statistical and geostatistical algorithms, soil pollution indices and geochemical & geomorphological/climate variables (element concentration, watercourses, winds, slope, orientation and visibility). The methodology proposed is exemplified through a comprehensive soil sampling in an area surrounding a former As-Hg mine that presents several sources of pollutants (abandoned mining spoil heaps, metallurgical waste, old chimneys, etc.). Factor analysis identified four main pollutants of concern: Hg, As, Pb and Sb. The mobility of the most abundant PTEs, especially As, and, to a minor extent, Hg, showed a clear influence of climatic/geomorphological variables. Moreover, the pollution indices confirmed that although the soils in the areas around the spoil heaps contain higher concentrations of the pollutants, the influence of the chimneys is present in the whole study area and depends on factors such as orientation and visibility. In contrast, the fingerprint of the spoil heaps showed a PTE distribution more associated with the slope factor and the presence of watercourses eroding the heaps. All things considered, the methodology proposed revealed PTE sources and distribution in a highly complex site and may therefore find application in similar scenarios of contamination.Boente, C., Baragaño, D., García-González, N., Forján, R., Colina, A., & Gallego, J. R. (2022). A holistic methodology to study geochemical and geomorphological control of the distribution of potentially toxic elements in soil. In CATENA (Vol. 208, p. 105730). Elsevier BV. https://doi.org/10.1016/j.catena.2021.10573

Phytoremediation potential depends on the degree of soil pollution: a case study in an urban brownfield

Phytoremediation is a cost-effective nature-based solution for brownfield reclamation. The choice of phytoextraction or phytostabilization strategies is highly relevant when planning full-scale treatments. A suitable approach to identify such species involves the evaluation of plants that grow spontaneously on the contaminated sites. Here, we sought to determine the phytoremediation potential of three spontaneous plant species, namely the trees Acer pseudoplatanus L (A. pseudoplatanus) and Betula celtiberica Rothm. & Vasc (B. celtiberica), and the shrub Buddleja davidii Franch (B. davidii), for the recovery of an urban brownfield. To determine the response of the species to the degree of contamination, we conducted soil and vegetation sampling inside and outside the site. The concentrations of As, Cu, and Zn in soil and plant samples were measured, and then various indexes related to phytoremediation were calculated. The translocation factor and transfer coefficient indicated that vegetation outside the brownfield had phytoextraction capacity while the same plants inside the brownfield revealed phytostabilization properties. Given our results, we propose that the selected species are suitable for phytostabilization strategies in areas with high concentrations of contaminants, whereas they could be used for phytoextraction only in soils with low or moderate levels of pollution.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This research was partially funded by the European Commission project LIFE I + DARTS (LIFE11ENV/ES/000547)

Study of PM2.5-bound polycyclic aromatic hydrocarbons and anhydro-sugars in ambient air near two Spanish oil refineries: Covid-19 effects

We report the results from a 12 month-long study of the organic compounds associated to PM2.5 samples collected around two petroleum refineries (4 samples/month/site) in two complex industrial zones reporting atmospheric pollution issues in the past (Estuary of Huelva and Bay of Algeciras, Spain). Sampling campaign was done from March 2020 when a Covid-19 lockdown was established at Spain to March 2021. Concentrations of fine particulate polycyclic aromatic hydrocarbons (PAHs) and anhydrosugars were separately measured using gas chromatography-mass spectrometry (GC-MS) and ion chromatography-amperometric detection (IC-PAD). The annual average abundances of PM2.5-bound benzo[a]pyrene (BaP) are 0.024 and 0.013 ng˖m−3 at La Rábida and Puente Mayorga monitoring stations, while both sites have annual average concentrations of levoglucosan in PM2.5 of 14.98 and 9.78 ng˖m−3, respectively. Seasonal variations are observed for concentrations of ƩPAHs and total anhydrosugars in both sampling sites. For PAHs, the highest concentrations averaging c. a. 0.400 (La Rábida) and 0.350 ng m−3 (Puente Mayorga) are reported in cold months during December 2020-Febraury 2021 (post-lockdown period), compared to the lowest levels averaging 0.111 and 0.211 ng˖m−3, respectively, in temperate months from mid-March 2020 to early June 2020 (0.284 and 0.321 ng m−3 on average annually), coinciding with the confinement and relaxation periods in Spain. Similarly, total anhydrosugars show the highest values of 81.80 ng˖m−3 (La Rábida) and 53.52 ng˖m−3 (Puente Mayorga) in winter and lowest values of 2.71 ng˖m−3 and 3.30 ng˖m−3 into the lockdown period (22.51 and 14.09 ng˖m−3 on average annually). Except phenanthrene, PAHs are present in PM2.5 principally as result of motor vehicle exhausts. Levoglucosan, a tracer for biomass burning, peaked in December 2020 and January 2021, during the high residential wood-burning season. In addition, multivariate analysis was used to assess the origin of organic components of PM2.5 samples. The two principal components are characterized by the grouping of heavy PAHs associated to vehicular traffic, and anhydrosugars indicating biomass burning emissions, respectively.We are grateful to the project of the Ministry of Science, Innovation and Universities of Spain (Project RTI 2018-095937-B-I00), the cofinanced project by the Andalusian Government and the EU (PY18- 2332), and the Environmental Agency of Andalusia for financial and technical support. Carlos Boente obtained a post-doctoral contract within the program PAIDI 2020 (Ref 707 DOC 01097), co-financed by the Junta de Andalucía (Spain) and the EU. Funding for open access charge: Universidad de Huelva / CBUA

Impact of Potentially Toxic Compounds in Cow Milk: How Industrial Activities Affect Animal Primary Productions

Potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) frequently coexist in soils near industrial areas and sometimes in environmental compartments directly linked to feed (forage) and food (milk) production. However, the distribution of these pollutants along the dairy farm production chain is unclear. Here, we analyzed soil, forage, and milk samples from 16 livestock farms in Spain: several PTEs and PAHs were quantified. Farms were compared in terms of whether they were close to (5 km) industrial areas. The results showed that PTEs and PAHs were enriched in the soils and forages from farms close to industrial areas, but not in the milk. In the soil, the maximum concentrations of PTEs reached 141, 46.1, 3.67, 6.11, and 138 mg kg-1 for chromium, arsenic, cadmium, mercury, and lead, respectively, while fluoranthene (172.8 µg kg-1) and benzo(b)fluoranthene (177.4 µg kg-1) were the most abundant PAHs. Principal component analysis of the soil PTEs suggested common pollution sources for iron, arsenic, and lead. In the forage, the maximum contents of chromium, arsenic, cadmium, mercury, and lead were 32.8, 7.87, 1.31, 0.47, and 7.85 mg kg-1, respectively. The PAH found in the highest concentration in the feed forage was pyrene (120 µg kg-1). In the milk, the maximum PTE levels were much lower than in the soil or the feed forages: 74.1, 16.1, 0.12, 0.28, and 2.7 µg kg-1 for chromium, arsenic, cadmium, mercury, and lead, respectively. Neither of the two milk samples exceeded the 20 µg kg-1 limit for lead set in EU 1881/2006. Pyrene was the most abundant PAH found in the milk (39.4 µg kg-1), while high molecular weight PAHs were not detected. For PTEs, the results showed that soil-forage transfer factors were higher than forage-milk ratios. Our results suggest that soils and forages around farms near industries, as well as the milk produced from those farms, have generally low levels of PTE and PAH contaminants.This research was funded by the Spanish Ministry of Science and Innovation (PID2020- 117282RB-I00, MCI-20-PID2019-000081, PID2019-109698GB-I00, PID2021-126010OR-I00), and by Principado de Asturias Regional Government co-financed by the European Union through the European Regional Development Fund (grants IDI/2021/000081 and IDI/2021/000102). S.F. received an FPI fellowship (grant BES-2017-081314) supported by MCIN/AEI/10.13039/501100011033 and the Investments for the Future program of the European Social Fund, “El FSE invierte en tu futuro”

Source apportionment of potentially toxic PM10 near a vast metallic ore mine and health risk assessment for residents exposed

Mining is an economic activity that traditionally releases large amounts of particulate matter into the atmosphere because of the procedures required to process the mineral. In particular, polymetallic ores are environmentally harmful as they can enrich potentially toxic elements, which may cause adverse effects to humans and ecosystems due to their toxicity. The aim was to assess the impact on health of this type of mining on nearby populations. Accordingly, it was conducted an extensive PM10 sampling campaign during the entirety of 2021 through a total of 248 filters placed in three villages close to the Rio Tinto district (Southwest Spain), which is one of the largest Cu mines in the world. A total of 58 major and trace elements were analysed, along with organic carbon/elemental carbon, cations, and anions. The mean PM10 concentrations were high during spring (47 μgPM10⋅m−3) and summer (56 μgPM10⋅m−3) in the population closest to the mine, wherein values surpassed the annual and daily limit values, but were lower in the other two villages. Moreover, high enrichment of As (annual maximum mean of 6.2 ng⋅m−3), Cu (70 ng⋅m−3), Pb (19 ng⋅m−3), and Zn (50 ng⋅m−3) was observed in all locations. A positive matrix factorization (PMF) was primarily used to assess the origins of this particulate matter, revealing that the impact of the mine reduced considerably over a long distance, with contributions ranging from 36% at the mine's outskirts to 8% further away from it, which coincides with the features of the mine during the abandonment phase (2001–2015). Despite this, the risk assessment revealed that the carcinogens were within the permissible exposure limits even in the closest village, indicating a minor concern for the inhabitants from a toxicological perspective.Funding for open access charge: Universidad de Huelva / CBUA

A novel application of mobile low-cost sensors for atmospheric particulate matter monitoring in open-pit mines

The authors are grateful to Atalaya Mining Company for giving the permission to carry out this research on their facilities and for their active support. Carlos Boente obtained a post-doctoral contract within the program PAIDI 2020 (Ref 707 DOC 01097) and the PY18-2332 Project, co-financed by the Junta de Andalucía (Andalusian Government), Spain and the EU. Funding for open access charge: Universidad de Huelva/CBUA, Spain

Optimising characterization and remediation techniques for potentially toxic elements in polluted soils

Tesis con mención internacional. Tesis doctoral por el sistema de compendio de publicacionesEsta investigación tiene por objeto desarrollar técnicas para la caracterización y remediación de suelos contaminados por elementos traza potencialmente tóxicos (Ing.: Potentially Toxic Elements, PTEs). Estos, por su toxicidad y peligrosidad para el medioambiente y la salud humana, constituyen el núcleo central de estudio. Mediante los procesos de caracterización, se busca identificar los contaminantes presentes en un suelo, estudiar su distribución espacial y evaluar sus posibles fuentes de emisión u orígenes. Por otro lado, la remediación de terrenos contaminados busca la eliminación o reducción de la concentración de los PTEs en el suelo. De esta manera, esta tesis abarca todo el proceso de vida de un contaminante en un suelo; desde que este accede al mismo procedente de una fuente, hasta que es eliminado. El trabajo es presentado como un compendio de 4 publicaciones. Dos relativas a las tecnologías de caracterización, y dos centradas en las de remediación. Como avances más destacables en labores de caracterización, destaca la sinergia creada entre la estadística univariante, multivariante y la geoestadística (krigeado ordinario) para dar respuesta a los objetivos mencionados anteriormente. Además, estos se complementan con el desarrollo de un nuevo indicador de contaminación (Ing.: Soil Pollution Index, SPI) y la adaptación de la teoría de datos composicionales para introducir el nuevo concepto de Enriquecimiento Relativo del Contaminante (Ing.: Relative Enrichment of the Pollutant, RE). Todo ello teniendo considerando las diferentes escalas de trabajo y teniendo en perspectiva los Niveles Genéricos de Referencia. Las acciones de remediación están focalizadas a mejorar la técnica del lavado de suelos. Se han utilizado diferentes equipos magnéticos y gravimétricos con suelos contaminados por distintas fuentes. Se proponen además varios métodos para la valoración de la eficiencia de los ensayos: validación del análisis atributivo y el nuevo Índice de Éxito (Ing.: Success Score). Adicionalmente, la tesis sienta las bases de una nueva técnica de remediación: El lavado de suelos asistido por nanopartículas de hierro cerovalente. Junto a esta se propone una nueva formulación basada en cuantificaciones magnéticas, cuyo objeto es evaluar la eficacia en la separación de los contaminantes de las técnicas empleadas, así como actuar de trazador de la distribución de nanopartículas en las muestras

Correlation between Geochemical and Multispectral Patterns in an Area Severely Contaminated by Former Hg-As Mining

In the context of soil pollution, plants suffer stress when exposed to extreme concentrations of potentially toxic elements (PTEs). The alterations to the plants caused by such stressors can be monitored by multispectral imagery in the form of vegetation indices, which can inform pollution management strategies. Here we combined geochemistry and remote sensing techniques to offer a preliminary soil pollution assessment of a vast abandoned spoil heap in the surroundings of La Soterraña mining site (Asturias, Spain). To study the soil distribution of the PTEs over time, twenty-seven soil samples were randomly collected downstream of and around the main spoil heap. Furthermore, the area was covered by an unmanned aerial vehicle (UAV) carrying a high-resolution multispectral camera with four bands (red, green, red-edge and near infrared). Multielement analysis revealed mercury and arsenic as principal pollutants. Two indices (from a database containing up to 55 indices) offered a proper correlation with the concentration of PTEs. These were: CARI2, presenting a Pearson Coefficient (PC) of 0.89 for concentrations >200 mg/kg of As; and NDVIg, PC of −0.67 for >40 mg/kg of Hg. The combined approach helps prediction of those areas susceptible to greatest pollution, thus reducing the costs of geochemical campaigns