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Silica-immobilization of Geobacter sulfurreducens for constructing ready-to-use artificial bioelectrodes
No full textGeoenvironmental characterization of unstable abandoned mine tailings combining geophysical and geochemical methods (Cartagena-La Union district, Spain)
No full textThis study presents the results of the geoenvironmental characterization of the Brunita mine pond in the Cartagena-La Unión mining district, Murcia (SE Spain). The main objective was to evaluate the present conditions of the mine tailings in order to identify related environmental hazards. Since 1956, the Brunita mine tailings were being stored in four stepped ponds at the watercourse of a NNO-SSE trending ravine. Subsequently, they were stored in a single, large pond. After the closure of the pond operations, certain work on dike stabilization was performed and debris from the Brunita mine started to accumulate. The mining works for > 50 years have led to the complete burial of the surrounding valleys and hills by mine waste material. Electrical resistivity tomography (ERT) has allowed the determining of both the general geometry of the pond base and the thickness of the mine tailings. Surveys along a total of 6 ERT profiles, 3 longitudinal and 3 transverse profiles to the largest dimension of the pond were carried out. The strong resistivity contrast between the infilling and the bedrock is high enough to clearly define the bottom pond boundary. Low resistivity values ( 200 Ω·m correspond to the Paleozoic rocks that constitute the base of the deposit. Vertical steps have been recognized defining strong variations in the thickness of the deposit. This geometry results from the interaction between the paleotopography of the previous valley and the different growth stages of the deposit. The depth of the pond's base obtained from two boreholes has confirmed the results obtained from ERT profiles. Significant amounts of pyrite and siderite and an appreciable presence of sphalerite and galena were determined by XRD of representative samples. Accordingly, high contents of toxic metals (Cd, Cu, Pb, Sn and Zn) and As were detected in chemical analyses, which show the potential of the tailings to release substantial amounts of these pollutants into the surrounding soils and watercourses. AMD has been identified and percolation through the base of the pond could occur at its northeast sector, where a low resistivity area is recognized. The manifest instability of the tailings pond makes it necessary to include physical stabilization in remediation and monitoring in order to minimize the environmental impact of the tailings on the areas affected, which is located in one of the most popular tourist areas in SE Spain
Predictive models in ecotoxicology: bridging the gap between scientific progress and regulatory applicability. Foreword
No full textIn the last decades, modelling approaches in the context of environmental risk assessment for chemicals have been under the spotlight of researchers in academia, regulatory bodies and industry. This is because mathematical and simulation models allow to gain deeper mechanistic understanding of fate and effect processes of organic contaminants in the environment. In addition, models make it possible to predict the toxic effects of compounds along with other relevant properties, such as biodegradability, uptake and bioaccumulation. Mathematical and simulation models have here unbeatable advantages: once established and tested, they allow the prediction of behaviour and effects of contaminants for large compound libraries and for different environmental conditions, while, at the same time, reducing animal testing, experimentation costs and time efforts. Hence, the application of models allows to increase the number of tested environmental scenarios, as well as the level of environmental safety, at lower monetary and ethical costs
Effects of temperature, genetic variation and species competition on the sensitivity of algae populations to the antibiotic enrofloxacin
No full textPrimary producers are amongst the most sensitive organisms to antibiotic pollution in aquatic ecosystems. To date, there is little information on how different environmental conditions may affect their sensitivity to antibiotics. In this study we assessed how temperature, genetic variation and species competition may affect the sensitivity of the cyanobacterium Microcystis aeruginosa and the green-algae Scenedesmus obliquus to the antibiotic enrofloxacin. First, we performed single-species tests to assess the toxicity of enrofloxacin under different temperature conditions (20°C and 30°C) and to assess the sensitivity of different species strains using a standard temperature (20°C). Next, we investigated how enrofloxacin contamination may affect the competition between M. aeruginosa and S. obliquus. A competition experiment was performed following a full factorial design with different competition treatments, defined as density ratios (i.e. initial bio-volume of 25/75%, 10/90% and 1/99% of S. obliquus/M. aeruginosa, respectively), one 100% S. obliquus treatment and one 100% M. aeruginosa treatment, and four different enrofloxacin concentrations (i.e. control, 0.01, 0.05 and 0.10mg/L). Growth inhibition based on cell number, bio-volume, chlorophyll-a concentration as well as photosynthetic activity were used as evaluation endpoints in the single-species tests, while growth inhibition based on measured chlorophyll-a was primarily used in the competition experiment. M. aeruginosa photosynthetic activity was found to be the most sensitive endpoint to enrofloxacin (EC50-72h =0.02mg/L), followed by growth inhibition based on cell number. S. obliquus was found to be slightly more sensitive at 20°C than at 30°C (EC50-72h cell number growth inhibition of 38 and 41mg/L, respectively), whereas an opposite trend was observed for M. aeruginosa (0.047 and 0.037mg/L, respectively). Differences in EC50-72h values between algal strains of the same species were within a factor of two. The competition experiment showed that M. aeruginosa growth can be significantly reduced in the presence of S. obliquus at a density ratio of 75/25% M. aeruginosa/S. obliquus, showing a higher susceptibility to enrofloxacin than in the single-species test. The results of this study confirm the high sensitivity of cyanobacteria to antibiotics and show that temperature and inter-strain genetic variation may have a limited influence on their response to them. The results of the competition experiment suggest that the structure of primary producer communities can be affected, at least temporarily, at antibiotic concentrations close to those that have been measured in the environment
Seasonal dynamics of microcystin-degrading bacteria and toxic cyanobacterial blooms: Interaction and influence of abiotic factors
No full textMassive proliferations of cyanobacteria coexist and have different interactions with other microorganisms, including microcystin (MC)-degrading bacteria. Despite their relevance in the environment for the removal of MCs, this bacterial community has been scarcely studied. The influence of physicochemical factors and the seasonal dynamics of toxic cyanobacteria on the relative abundance and seasonal dynamics of the MC-degrading bacterial community with mlr genes (mlr+) were investigated during a two-year study at a water reservoir in central Spain. The capacity of the total bacterial community on the degradation of MCs during the whole period of study was also evaluated. The results showed that the relative abundance of mlr+ bacteria started to increase after the increase in the relative abundance of toxic cyanobacteria and MC concentrations in the water, indicating a related seasonal dynamic and an important interaction between the two communities. The correspondence of several peaks of mlr+ bacteria with decreases in the relative abundance of toxic cyanobacteria and vice versa may also suggest a possible antagonistic relationship that deserves an in-depth study. The lack of a significant relationship between the physicochemical factors and the temporal shifts of both MC producers and degraders also supports the notion that the interaction of the two communities is an important driver of their seasonal dynamics in nature. Regarding the capacity of the total bacterial community for the degradation of MCs, this capacity was only observed during the toxic cyanobacterial bloom episodes, highlighting the importance of the pre-exposure to MCs in the reservoir for triggering the MC biodegradation process
Memorandum on weight of evidence and uncertainties Revision 2018
No full textThis Memorandum is focussed on how to use the weight of evidence approach (WoE)to conduct a risk assessment for stressors to which humans and/or the environment may
be exposed. It is intended to complement the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) report on the identification of emerging issues
and the work on the challenges in future risk assessment.
The aim of this document is to support the use of the WoE, wherever appropriate, for the risk assessment activities of
the Scientific Committee on Health, Environmental and Emerging Risks (SCHEER). In addition, it should support the consistency in the work of different EU bodies performing risk assessments.
Scientific evidence consists of observations, experimental and model results and expert judgements that serve to support, refute, or modify a scientific hypothesis or theory. The search for relevant information and data
for the SCHEER comprises of identifying, collecting and selecting possible sources of evidence in order to perform a risk assessment and/or to answer the specific questions being asked. According to the issue being addressed, the SCHEER may utilise data provided by the DG tasking the SCHEER, or provided by a third party (e.g. stakeholder reports, submissions such as confidential
data provided by companies or applicants), reports and Opinions of other scientific, governmental or international bodies, scientific (peer-reviewed) publications, meta-analysis and systematic reviews
or personal communications.
The WoE is an iterative process involving:
- Problem formulation
- Identification, collection and selection of the possible sources of evidence
- Assessment and weighing of individual lines of evidence
- Integration of lines of evidence
- Description of uncertainties
- Conclusion and reporting
For each line of evidence, the criteria of validity, reliability and relevance need to be applied and the overall quality has to be assessed. Several tools for the analysis and description of uncertainties are presented. In the integration of the different lines of evidence, the strength of the overall evidence depends on the consistency and the quality of the results. The weighing of the total evidence should be presented in a standard format. A system is proposed that classifies results of analysis for human and environmental risks in terms of:
−Strong weight of evidence: Coherent evidence from a primary line of evidence (human, animal, environment) and one or moreother lines of evidence (in particular
mode/mechanistic studies) in the absence of conflicting evidence from one of the other lines of evidence (no important data gaps)
−Moderate weight of evidence: good evidence from a primary line of evidence but evidence from several other lines is missing (important data gaps)
−Weak weight of evidence: weak evidence from the primary lines of evidence (severe data gaps)
−Uncertain weight of evidence: due to conflicting information from different lines of evidence that cannot be explained in scientific terms
−Weighing of evidence not possible: No suitable evidence availabl
Estudio de los suelos de los alrededores del Balneario de Paracuellos de Jiloca (Zaragoza)
No full textEl aprovechamiento de las aguas mineromedicinales como medio para sanar de forma natural se conoce desde épocas ancestrales. Sus acciones terapéuticas están condicionadas con los gases y las fases sólidas que contengan, y estos dependen del equilibrio y la composición de la atmosfera, los suelos y las rocas. Estos equilibrios están relacionados con la temperatura y la presión del sistema, y cualquier cambio puede producir una variación que afecte a los procesos de disolución y precipitación de los minerales, y por tanto, a la concentración de elementos químicos en las aguas. La composición del suelo juega un papel determinante ya que en su interior se producen reacciones de sorción-desorción, complejación-disociación, disolución-precipitación, que determinan la movilidad de los constituyentes orgánicos e inorgánicos que forman el suelo. En función del resultado de estas reacciones los elementos y compuestos pude quedarse, o alcanzar las aguas subyacentes. En este trabajo analizamos las características edáficas de cuatro suelos muy representativos de los alrededores de la localidad de Paracuellos de Jiloca, localidad donde se encuentra la casa balneario. Pertenece la zona al Sistema Ibérico, en el Valle del Jiloca, situado a una altitud de 586 msnm y se encuentra a 4,6 km de Calatayud. Son suelos con escaso desarrollo, tipo AC, formados a partir de materiales sedimentarios constituidos por conglomerados, calizas margosas y yesos. Presentan pHs básicos, poca materia orgánica, texturas gruesas, son carbonatados y están saturados, siendo el calcio el catión mayoritario
Predicting pesticide fate in small cultivated mountain watersheds using the DynAPlus model: Toward improved assessment of peak exposure
No full textThe use of plant protection products (PPPs) in agricultural areas implies potential chemical loadings to surface waters, which can pose a risk to aquatic ecosystems and human health. Due to the spatio-temporal variability of PPP applications and of the processes regulating their transport to surface waters, aquatic organisms are typically exposed to pulses of contaminants. In small mountain watersheds, where runoff fluxes are more rapid due to the steep slopes, such exposure peaks are particularly likely to occur. In this work, a spatially explicit, dynamic model for predicting pesticide exposure in surface waters of cultivated mountain basins (DynAPlus) has been developed. The model has been appliedto a smallmountainwatershed (133 km2) located in the ItalianEastern Alps and characterized by intensive agriculture (apple orchards) around the main river and its tributaries. DynAPlus performance was evaluated for chlorpyrifos through experimental monitoring, using samples collected during the 2011 and 2012 productive seasons. The comparison between predictions and measurements resulted in a good agreement (R2 = 0.49, efficiency factor 0.60), although a more accurate spatial information in the input scenario (e.g.,field-specific applications, rainfall amount, soil properties) would dramatically improve model performance. A set of illustrative simulations performed for three PPPs highlighted the potential role of DynAPlus in
improving exposure predictions for ecological risk assessment and pesticide management practices (e.g., for ac-
tive ingredient and application rate selection), as well as for planning efficient monitoring campaign
Hydrogeochemical characterization of a shallow alluvial aquifer: 1 baseline for groundwater quality assessment and resource management
No full textConsidering the progressive depletion of groundwater quantity and the alteration of superficial and groundwater
quality in the Madrid region, a highly populated area with extended urbanizations in the north and agricultural
activities in the south, we conducted a monitoring study over a period of 2.5 years (2015–2017). The
study was conducted in the Jarama-Tajuña shallow alluvial aquifer system located southeast of Madrid, where
the exploitation of the aquifer and the Jarama river have increased exponentially in the last decade being affected
by both urban and agricultural activities. Our aims were to provide: i) a geochemical characterization
of the surface and groundwater properties; ii) identify the process responsible for the geochemical evolution
and mineralization of the waters; iii) assess the water quality (i.e. nitrates, ammonia, sodium and chloride as
potential contaminants) and the water suitability for irrigation (SAR, Wilcox, KI and MH indexes); and iv)
identify the main sources of contamination in the area.
A set of plots, ion ratios, correlation coefficients, multivariate statistical analyses and indexes were performed.
Results indicated that rock weathering largely controls the hydrogeochemistry of the system and that
wastewater treatment plant discharges and agricultural practices significantly affect the composition of the
water, causing an important decline of both surface and groundwater chemical quality. Nonetheless, water
suitability for irrigation is admissible. Thus, taking additional measures to increase its quality are not necessary.
With this study we aimed to establish a base line to evaluate future changes in the groundwater properties
from the Madrid region enabling the planners and policy makers to develop a strategy to mitigate the impact
of the exponential increase of urban and agriculture activities on groundwater resources
Biological and Bioelectrochemical Systems for Hydrogen Production and Carbon Fixation Using Purple Phototrophic Bacteria
No full textDomestic and industrial wastewaters contain organic substrates and nutrients that can be recovered instead of being dissipated by emerging efficient technologies. The aim of this study was to promote bio-hydrogen production and carbon fixation using a mixed culture of purple phototrophic bacteria (PPB) that use infrared radiation in presence or absence of an electrode as electron donor. In order to evaluate the hydrogen production under electrode-free conditions, batch experiments were conducted using different nitrogen (NH4Cl, Na-glutamate, N2 gas) and carbon sources (malic-, butyric-, acetic- acids) under various COD:N ratios. Results suggested that the efficiency of PPB to produce biogenic H2 was highly dependent on the substrates used. The maximum hydrogen production (H2_max, 423 mLH2/L) and production rate (H2_rate, 2.71 mLH2/Lh) were achieved using malic acid and Na-glutamate at a COD:N ratio of 100:15. Under these optimum conditions, a significant fixation of nitrogen in form of single-cell proteins (874.4 mg/L) was also detected. Under bio-electrochemical conditions using a H-cell bio-electrochemical device, the PPB were grown planktonic in the bio-cathode chamber with the optimum substrate ratio of malic acid and Na-glutamate. A redox potential of −0.5V (vs. Ag/AgCl) under bio-electrochemical conditions produced comparable amounts of bio-hydrogen but significantly negligible traces of CO2 as compared to the biological system (11.8 mLCO2/L). This suggests that PPB can interact with the cathode to extract electrons for further CO2 re-fixation (coming from the Krebs cycle) into the Calvin cycle, thereby improving the C usage. It has also been observed during cyclic voltammograms that a redox potential of −0.8 V favors considerably the electrons consumption by the PPB culture, suggesting that the PPB can use these electrons to increase the biohydrogen production. These results are expected to prove the feasibility of stimulating PPB through bio-electrochemical processes in the production of H2 from wastewater resources, which is a field of special novelty and still unexplored