Behaviour of fuel organic compounds in contaminated soils and development of a phytoremediation procedure

Soil contamination with fuel derived organic compounds is a problem principally caused by emissions and residues from the petrochemical industry, traffic accidents, and accidental leaks in pipelines or in underground fuel storage tanks. Soils contaminated with fuels have a high environmental risk, since they can contaminate other environmental compartments, with the inherent risks for human health and for the environment. Sorption to soil particles, volatilization, leaching, degradation (chemical, photochemical and biological oxidation), plant translocation, etc., are the principal processes that will influence on the final fate of soil contaminants in the environment. In order to interpret, evaluate the risks and make decisions about the effects of fuel compounds and assure and adequate protection of the environment, it is very important to understand the toxicology, analytics and the behaviour and fate in the environment. Within this context, the present doctoral thesis has the following objectives: Development of analytical methods for volatile compounds (MTBE, ETBE and BTEX) and diesel range organics (DRO) in soil and water. Application of those methods to the characterization of a site contaminated with hydrocarbons. Study of the dynamics of petroleum contaminants in the soil-plant-water-air system through sorption and leaching experiments and a experiment with root exudates, to study the effect of plants on contaminant mobility through soils. Characterization of gasoline and diesel phytotoxicity, with crop plants bioassays. At last, application of a phytoremediation procedure with Lupinus luteus growing on the A and B horizons of a Cambisol contaminated with diesel (1%, w/w), with the inoculation of best plant growth promoting and degrader bacteria, with the best results from previous experiment. The experiments carried out in this thesis, allowed to obtain a wide knowledge of the behaviour of those contaminants in the soil system, and to predict their final fate in the environment, in addition to their toxic effect once released in soil. The proposed remediation techniques, through bacteria assisted phytoremediation, resulted in a clean, cheap, reliable and highly efficient technique, what predicts satisfactory results in its application to real soils

Desenvolvimento e optimização da extração headspace e microextração headspace em fase sólida para determinação de compostos voláteis de combustíveis em amostras ambientais

The application of an effective and sensitive analytical method to determine soil contaminants is a crucial step in monitoring and remediation processes. In the present work, we optimized the analysis of volatile organic compounds (VFOC) commonly present in fuel: oxygenates (FO-MTBE and ETBE-) and monoaromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene (BTEX). Headspace (HS) and headspace-solid phase microextraction (HS-SPME) were optimized in water samples, and validated for contaminated soils, using artificially spiked soils. Contaminants were identified and quantified by gas chromatography coupled to mass spectrometry (GC/MS). Matrix effect correction with surrogate standards resulted essential when analyzing soil samples, especially when the sample exerted a strong sorption on the contaminantsLa aplicación de metodologías analíticas sensibles y efectivas para la determinación de los contaminantes del suelo es una etapa crucial para la realización de experimentos de monitorización y remediación. En el presente trabajo, se optimizó el análisis de compuestos orgánicos volátiles (VFOC) comúnmente presentes en combustibles: incluyendo compuestos oxigenados (FO-MTBE y ETBE-) e hidrocarburos monoaromáticos, tales como benceno, tolueno, etilbenceno y xileno (BTEX). Los métodos de extracción en headspace (HS) y microextracción en fase sólida en headspace (HS-SPME) fueron optimizados para aguas contaminadas y después validadas para suelos, utilizando muestras contaminadas de forma artificial. La corrección del efecto matriz con estándares tipo surrogate fue esencial para el análisis de muestras de suelos, especialmente para aquellas que ejercían una fuerte adsorción sobre los contaminantesA aplicação de um método analítico eficaz e sensível para determinar contaminantes orgânicos do solo e da água é um passo essencial durante os processos de monitorização e recuperação ambiental. No presente trabalho optimizou-se a análise de alguns compostos orgânicos voláteis que surgem, usualmente, nos combustíveis: compostos oxigenados (FOMTBE e ETBE-) e hidrocarbonetos monoaromáticos tais como benzeno, tolueno, etilbenzeno e xileno (BTEX). As metodologias de extracção headspace (HS) e microextracção em fase sólida em modo headspace (HS-SPME) foram otimizadas em amostras de água e validadas para amostras de diferentes solos contaminados artificialmente. Os contaminantes orgânicos foram identificados e quantificados por cromatografia gasosa associada a espectrometria de massa (GC/MS). A correção do efeito da matriz com padrões surrogate foi essencial para a análise das amostras de solo, especialmente em solos que apresentavam uma forte adsorção dos contaminantesS

Emergent properties of microbial activity in heterogeneous soil microenvironments:Different research approaches are slowly converging, yet major challenges remain

Over the last 60 years, soil microbiologists have accumulated a wealth of experimental data showing that the usual bulk, macroscopic parameters used to characterize soils (e.g., granulometry, pH, soil organic matter and biomass contents) provide insufficient information to describe quantitatively the activity of soil microorganisms and some of its outcomes, like the emission of greenhouse gases. Clearly, new, more appropriate macroscopic parameters are needed, which reflect better the spatial heterogeneity of soils at the microscale (i.e., the pore scale). For a long time, spectroscopic and microscopic tools were lacking to quantify processes at that scale, but major technological advances over the last 15 years have made suitable equipment available to researchers. In this context, the objective of the present article is to review progress achieved to date in the significant research program that has ensued. This program can be rationalized as a sequence of steps, namely the quantification and modeling of the physical-, (bio)chemical-, and microbiological properties of soils, the integration of these different perspectives into a unified theory, its upscaling to the macroscopic scale, and, eventually, the development of new approaches to measure macroscopic soil characteristics. At this stage, significant progress has been achieved on the physical front, and to a lesser extent on the (bio)chemical one as well, both in terms of experiments and modeling. In terms of microbial aspects, whereas a lot of work has been devoted to the modeling of bacterial and fungal activity in soils at the pore scale, the appropriateness of model assumptions cannot be readily assessed because relevant experimental data are extremely scarce. For the overall research to move forward, it will be crucial to make sure that research on the microbial components of soil systems does not keep lagging behind the work on the physical and (bio)chemical characteristics. Concerning the subsequent steps in the program, very little integration of the various disciplinary perspectives has occurred so far, and, as a result, researchers have not yet been able to tackle the scaling up to the macroscopic level. Many challenges, some of them daunting, remain on the path ahead

Tuberculosis Epidemiology and Spatial Ecology at the Cattle-Wild Boar Interface in Northern Spain

[EN] Tuberculosis (TB) is a contagious chronic disease due to infection with Mycobacterium tuberculosis complex (MTC) bacteria. Monitoring of wildlife, especially potential reservoirs, is important for detecting changes in disease occurrence and assessing the impact of interventions. Here, we examined whether wild boar (Sus scrofa) may contribute to the re-emergence of TB in Asturias (10,604 km2), northern Spain. Although this province was declared free of TB in cattle in November 2021, MTC bacteria remain prevalent in several “hotspots,” with the European badger (Meles meles) suggested as a TB potential wild reservoir. Drawing on data from the Spanish National Bovine Tuberculosis Eradication Program and the Government of the Principality of Asturias covering the period 2014–2020, we analyzed the prevalence of TB in cattle and wild boar in this region. In hotspots (592 km2), we also investigated the ranging behavior and habitat use of five cows that belonged to farms with a history of TB and six trapped sympatric wild boar. During the observation period, TB prevalence was 0.14% among cattle overall and 0.13–0.41% in hotspots, which was much lower than the prevalence in wild boar, which was 3.15% overall and 5.23–5.96% in hotspots. Infected cattle and infected wild boar in hotspots shared the same strains of M. bovis, and GPS tracking showed spatiotemporal overlap between the species, mainly around pastures during sunrise (06:00–07:00 h) and sunset (19:00–20:00 h). Our results suggest that in addition to cattle and badgers, wild boar possibly help maintain TB in northern Spain, increasing the host richness that influences TB transmission risk in the area, which should be taken into account in monitoring and eradication efforts.SIThe authors would like to thank our colleagues from SERIDA, the Government of Asturias, SaBio-IREC, VISAVET, and the University of León for their help and support. This work is a result of the I+D+i research project RTI2018-096010-B-C21, funded by the Spanish MCIN/AEI/10.13039/501100011033/Ministry of Science, Innovation and the European Regional Development Funds (FEDER Una manera de hacer Europa), and of PCTI 2021–2023 (GRUPIN: IDI2021-000102) funded by Principado de Asturias and FEDER. This work was partially financed by the Ministerio de Agricultura, Pesca y Alimentación. Gloria Herrero-García is funded by Junta de Castilla y León and FSE (grant no. LE036-20

Wild boar tuberculosis in Iberian Atlantic Spain: a different picture from Mediterranean habitats

BACKGROUND Infections with Mycobacterium bovis and closely related members of the Mycobacterium tuberculosis complex (MTC) are shared between livestock, wildlife and sporadically human beings. Wildlife reservoirs exist worldwide and can interfere with bovine tuberculosis (TB) eradication efforts. The Eurasian wild boar (Sus scrofa) is a MTC maintenance host in Mediterranean Iberia (Spain and Portugal). However, few systematic studies in wild boar have been carried out in Atlantic regions. We describe the prevalence, distribution, pathology and epidemiology of MTC and other mycobacteria from wild boar in Atlantic Spain. A total of 2,067 wild boar were sampled between 2008 and 2012. RESULTS The results provide insight into the current status of wild boar as MTC and Mycobacterium avium complex (MAC) hosts in temperate regions of continental Europe. The main findings were a low TB prevalence (2.6%), a low proportion of MTC infected wild boar displaying generalized TB lesions (16.7%), and a higher proportion of MAC infections (4.5%). Molecular typing revealed epidemiological links between wild boar and domestic - cattle, sheep and goat - and other wildlife - Eurasian badger (Meles meles) and red fox (Vulpes vulpes) - hosts. CONCLUSIONS This study shows that the likelihood of MTC excretion by wild boar in Atlantic habitats is much lower than in Mediterranean areas. However, wild boar provide a good indicator of MTC circulation and, given the current re-emergence of animal TB, similar large-scale surveys would be advisable in other Atlantic regions of continental Europe

Spatial and Temporal Distribution of Mycobacterium tuberculosis Complex Infection in Eurasian Badger (Meles meles) and Cattle in Asturias, Spain

Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/)[EN] The present work investigated the prevalence, spatial distribution, and temporal distribution of tuberculosis (TB) in free-ranging Eurasian badgers (Meles meles) and cattle in Asturias (Atlantic Spain) during a 13-year follow-up. The study objective was to assess the role of badgers as a TB reservoir for cattle and other sympatric wild species in the region. Between 2008 and 2020, 673 badgers (98 trapped and 575 killed in road traffic accidents) in Asturias were necropsied, and their tissue samples were cultured for the Mycobacterium tuberculosis complex (MTC) isolation. Serum samples were tested in an in-house indirect P22 ELISA to detect antibodies against the MTC. In parallel, data on MTC isolation and single intradermal tuberculin test results were extracted for cattle that were tested and culled as part of the Spanish National Program for the Eradication of Bovine TB. A total of 27/639 badgers (4.23%) were positive for MTC based on bacterial isolation, while 160/673 badgers (23.77%) were found to be positive with the P22 ELISA. The rate of seroposi-tivity was higher among adult badgers than subadults. Badger TB status was spatially and tempo-rally associated with cattle TB status. Our results cannot determine the direction of possible interspecies transmission, but they are consistent with the idea that the two hosts may exert infection pressure on each other. This study highlights the importance of the wildlife monitoring of infection and disease during epidemiological interventions in order to optimize outcomes.SIThis work was funded by the Ministerio de Ciencia, Innovación y Universidades (MCIU), the Agencia Estatal de Investigación (AEI) reference project RTI2018-096010-B-C21 (FEDER co-funded), PCTI 2018–2020 (GRUPIN: IDI2018-000237), and FEDER and Ministerio de Agricultura, Pesca y Alimentación. C.B.V. was supported by a grant from the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain. Publication costs were covered with funds from RTI2018- 096010-B-C21 (FEDER co-funded). T.D.B. was supported by a fellowship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES; process number 88887.511077/2020-00)The authors acknowledge invaluable support from their colleagues at SERIDA (Miguel Prieto and Alberto Espí), the University of León, the Servicio de Espacios Protegidos y Conservación de la Naturaleza, the Dirección General del Medio Natural y Planificación Rural del Principado de Asturias, the Servicio de Sanidad y Producción Animal del Principado de Asturias, the Regional Animal Health Laboratory of Principado de Asturias, VISAVET and Instituto de Salud Carlos III. We thank A. Chapin Rodríguez (Creaducate Consulting GmbH) for critically reviewing the manuscript

Lessons from a landmark 1991 article on soil structure: distinct precedence of non-destructive assessment and benefits of fresh perspectives in soil research

In 1991, at the launch of a national symposium devoted to soil structure, the Australian Society of Soil Science invited Professor John Letey to deliver a keynote address, which was later published in the society’s journal. In his lecture, he shared the outcome of his reflexion about what the assessment of soil structure should amount to, in order to produce useful insight into the functioning of soils. His viewpoint was that the focus should be put on the openings present in the structure, rather than on the chunks of material resulting from its mechanical dismantlement. In the present article, we provide some historical background for Letey’s analysis, and try to explain why it took a number of years for the paradigm shift that he advocated to begin to occur. Over the last decade, his perspective that soil structure needs to be characterised via non-destructive methods appears to have gained significant momentum, which is likely to increase further in the near future, as we take advantage of recent technological advances. Other valuable lessons that one can derive from Letey’s pioneering article relate to the extreme value for everyone, even neophytes, to constantly ask questions about where research on given topics is heading, what its goals are, and whether the methods that are used at a certain time are optimal

Environmental DNA: A promising factor for tuberculosis risk assessment in multi-host settings

[EN] Attaining and maintaining the Official Tuberculosis Free status continues to be a challenge when several domestic and wild hosts contribute to the maintenance of the Mycobacterium tuberculosis complex (MTC). Local tuberculosis hotspots are sometimes identified in cattle in low-prevalence regions. We have, therefore, studied one such hotspot in depth in order to produce an epidemiological diagnosis. Host population size and MTC prevalence were estimated in selected wildlife and in livestock, while on-cattle environmental DNA detection was additionally used as a proxy for risk of exposure at the farm (herd) level. Positive skin test reactors were found on16 of the 24 cattle farms studied in the period 2012-2016. Although all goats tested negative to the skin test during this period, MTC was confirmed in four sheep at slaughter, thus indicating an unknown prevalence of infection in this host species. With regard to wildlife, the prevalence of MTC infection based on culture was 8.8% in the case of wild boar (Sus scrofa), and the only road-killed badger (Meles meles) submitted for culture tested positive. Two criteria were employed to divide the cattle farms into higher or lower risk: tuberculosis testing results and environmental DNA detection. Environmental MTC DNA detection yielded significant differences regarding "use of regional pastures" and "proximity to woodland". This study suggests that on-animal environmental DNA sampling may help when assessing contact risk as regards MTC in livestock at the herd level. This tool opens up new avenues of epidemiological research in complex multi-host settingsSIThis work was supported by the Programa de Tecnologı´as Avanzadas en Vigilancia Sanitaria (TAVS) from the Comunidad de Madrid (ref. S2013/ABI-2747). JMG holds a FPI predoctoral scholarship (BES-2015- 072206), funded by MINECO. This is a contribution to MINECO grant CGL2017-89866 WildDriver and EU-FEDER. This is also a contribution to Valle de Alcudia pilot project SG-2019-02 from PDR-CLM, and to GOSTU project EU-FEADER (AEIAGRI-PNDR-MAPA, ref. 20190020007521). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip