Toxic effect of the combined antibiotics ciprofloxacin, lincomycin, and tylosin on two species of marine diatoms

The role that antibiotics and other “emerging contaminants” play in shaping environmental microbial communities is of growing interest. The use of the prokaryotic metabolic inhibitors tylosin (T), lincomycin (L), and ciprofloxacin (C) in livestock and humans is both global and extensive. Each of these antibiotic compounds exhibits an affinity for sediment particles, increasing the likelihood of their deposition in the benthos of aquatic systems and each are often present in environmental samples. The purpose of this study was to determine if T, L, and C and their mixtures exhibit significant toxicity to two species of marine diatoms, an algal class comprised of ubiquitous eukaryotic primary producers. Subpopulations from laboratory cultures of Cylindrotheca closterium and Navicula ramosissima were reared in 24-well microtiter plates in the presence of single or combined antibiotics in dilution series. Population growth rates were assessed via epifluorescent microscopic cell counts, from which the half-max inhibitory concentrations (IC₅₀) were calculated and used as part of a toxic unit (TU) method for assessing mixture interactions. The single-compound IC₅₀'s were, for C. closterium: T = 0.27 mg L⁻¹, L = 14.16 mg L⁻¹, C = 55.43 mg L⁻¹, and for N. ramosissima: T = 0.99 mg L⁻¹, L = 11.08 mg L⁻¹, C = 72.12 mg L⁻¹. These values were generally higher than similar metrics for freshwater species. Mixture IC₅₀'s were generally synergistic against C. closterium and additive for N. ramosissima. Both single and combined treatments reduced or eliminated diatom motility. Monochemical responses were similar between species and were not useful for predicting mixture interactions. Mixtures had compound-specific and species-specific effects, favoring N. ramosissima. These results suggest that anthropogenic antibiotics may play a significant role in the ecology of environmental benthic microbial communities. They also suggest single-compound/species studies do not yield useful predictions of the ecological impact of anthropogenic pharmaceuticals.     

Survival of Escherichia coli in two sewage treatment plants using UV irradiation and chlorination for disinfection

We investigated the survival of Escherichia coli in two STPs utilising UV irradiation (STP-A) or chlorination (STP-B) for disinfection. In all, 370 E. coli strains isolated from raw influent sewage (IS), secondary treated effluent (STE) and effluent after the disinfection processes of both STPs were typed using a high resolution biochemical fingerprinting method and were grouped into common (C-) and single (S-) biochemical phenotypes (BPTs). In STP-A, 83 BPTs comprising 123 isolates were found in IS and STE, of which 7 BPTs survived UV irradiation. Isolates tested from the same sites of STP-B (n = 220) comprised 122 BPTs, however, only two BPTs were found post-chlorination. A representative isolate from each BPT from both STPs was tested for the presence of 11 virulence genes (VGs) associated with uropathogenic (UPEC) or intestinal pathogenic (IPEC) E. coli strains. Strains surviving UV irradiation were distributed among seven phylogenetic groups with five BPTs carrying VGs associated with either UPEC (4 BPTs) or IPEC (1 BPT). In contrast, E. coli strains found in STP-B carried no VGs. Strains from both STPs were resistant to up to 12 out of the 21 antibiotics tested but there was no significant difference between the numbers of antibiotics to which surviving strains were resistant to in these STPs. Our data suggests that some E. coli strains have a better ability to survive STPs utilising chlorination and UV irradiation for disinfection. However, strains that survive UV irradiation are more diverse and may carry more VGs than those surviving SPTs using chlorination.     

Photosynthesis and oxidative stress in the restinga plant species Eugenia uniflora L. exposed to simulated acid rain and iron ore dust deposition: Potential use in environmental risk assessment

The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPM_Fe) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPM_Fe application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers.     

Immediate and long-term impacts of UV-C irradiation on photosynthetic capacity, survival and microcystin-LR release risk of Microcystis aeruginosa

In this study, the immediate and long-term impacts of shortwave ultraviolet (UV-C) irradiation on photosynthetic capacity, survival, and recovery of Microcystis aeruginosa were investigated. The risk of microcystin-LR (MC-LR) release during irradiation was also estimated. The cell density was determined by a flow cytometry, and typical chlorophyll fluorescence parameters, including the effective quantum yield, photosynthetic efficiency and maximal electron transport rate, were measured by a pulse amplitude modulated (PAM) fluorometer. Under various UV-C dosages (140-4200 mJ cm⁻²), photosynthetic capacities were reduced, to different degrees, accompanied by slight cytoclasis and complete degradation of extracellular MC-LR immediately after irradiation. In a 6-d cultivation following UV-C irradiation, cell density and extracellular MC-LR in the samples treated by 140 mJ cm⁻² UV-C irradiation increased from 4.0 × 10⁶ cells mL⁻¹ and 8 μg L⁻¹ to 5.1 × 10⁶ cells mL⁻¹ and 20 μg L⁻¹, respectively. Significant M. aeruginosa cytoclasis (cell density from 4.0 × 10⁶ to 1.0 × 10⁶ cells mL⁻¹) and MC-LR release (2-25 μg L⁻¹) occurred when the UV-C dosage reached 350 mJ cm⁻². Cell cytoclasis and MC-LR release were enhanced in the cultivated samples under higher UV-C dosages. Results revealed that photosynthetic parameters were useful tools to predict the recovery profiles of M. aeruginosa cells, and the MC-LR release risk should be considered after UV-C inactivation.     

Effects of low doses of short-term gamma irradiation on growth and development through two generations of Pisum sativum

The effects of short-term gamma radiation on pea plants were investigated by exposing 5-day-old seedlings with doses ranging from 0 to 60 Gy, and studying plant growth and development over two generations after irradiation. Doses higher than 6 Gy significantly inhibited the G1 plant growth and productivity, and no seedling survived irradiation with 40 Gy and above. These effects were transmitted and were even more severe in the next generation, G2. Irradiated G1 (> or =10 Gy) and G2 (> or = 0.4 Gy) plants were significantly smaller than controls. The mean number of pods produced per plant was reduced by at least 20% at all doses in both G1 and G2. In parallel, the mean numbers of ovules and normally developed seeds per pod were significantly reduced after 10 Gy in G1 and after 0.4 Gy in G2, leading to a significant drop in seed production. This effect was correlated with a linear decrease in male fertility linked to abnormal meiosis (tetrads with micronuclei) as a function of doses from 0 to 10 Gy, in G1 and G2 plants. These long-term changes in plant development demonstrate a genomic instability induced by irradiation. However, there were neither quantitative nor qualitative changes in storage proteins in G1 seeds at any of the irradiation doses tested from 0 to 10 Gy.     

Effects of low- or medium-pressure ultraviolet lamp irradiation on Microcystis aeruginosa and Anabaena variabilis

A pure culture of Microcystis aeruginosa or Anabaena variabilis, the representatives of water blooming algae, was exposed to low-pressure (LP) or medium-pressure (MP) UV lamps. Irradiated pure culture suspension was subsequently incubated for 7d under white light fluorescent lamps. During incubation, profiles of the number of cells, DNA damage and photosynthetic activity were determined. When UV fluence was 600mJ/cm(2), M. aeruginosa cell numbers decreased throughout the 7-d incubation period, to produce 1.5log reduction (LP) or 1.2log reduction (MP) compared with control. The amount of DNA damage was 2.02x10(-4) ESS/base (LP) and 3.42x10(-4) ESS/base (MP) just after UV irradiation, which became 0.05x10(-4) ESS/base and 0.23x10(-4) ESS/base, respectively, after 3d incubation. However, cell number kept decreasing, even after DNA repair. Photosynthetic activity decreased by 1.5log within 1d (LP) or 3d (MP). Thus, reduction in photosynthetic activity could contribute to the reduction in M. aeruginosa cell numbers. A. variabilis cell numbers reduced by 2.3log (LP) or 2.2log (MP) during the 7-d incubation period; however, after DNA damage repair, cell number began to increase. The amount of DNA damage was 6.07x10(-4) ESS/base (LP) and 4.48x10(-4) ESS/base (MP) just after UV irradiation, which became 0.23x10(-4) ESS/base and 0.40x10(-4) ESS/base, respectively, after 3d incubation. No reduction was observed in photosynthetic activity/cell. Therefore, DNA damage is the main contributor of the reduction in cell number of A. variabilis.     

Quantitative and qualitative evaluation of phytoplankton communities by trichromatic chlorophyll fluorescence excitation with special focus on cyanobacteria

We present results that were obtained with a newly developed fluorometer, the 'PhytoSensor'. They are based on multi-wavelength excitation of chlorophyll fluorescence to detect the phytoplankton biomass and to identify main taxons (among cyanobacteria, green and brown microalgae). A method to evaluate the photosynthetic potential of the phytoplankton was established. Attention was focused on the measurement of the cyanobacterial biomass. A modelling to distinguish between the two spectral groups (blue and red) of cyanobacteria as a function of their pigments and physiological status is proposed. The main innovation of the device results in the recording of the fluorescence induction kinetics of the phytoplankton to confirm and refine the evaluation of the taxonomic composition. The PhytoSensor abilities were compared with pigment analysis, commercial fluorometers, particle and microscopic counting and identification. The PhytoSensor has been used with success to monitor the dynamics of phytoplankton in drinking-water supply reservoirs in Southeast Asia.     

Comparison of six different sewage treatment processes—Reduction of estrogenic substances and effects on gene expression in exposed male fish

Treated sewage effluents often contain a mixture of estrogenic compounds in low concentrations. The total combined activity of these, however, may be sufficiently high to affect the reproduction of aquatic vertebrates. The introduction of advanced treatment technologies has been suggested as a way to remove micro-contaminants, including estrogenic substances. In this study, one municipal influent was treated with six different processes in parallel on a semi-large scale in order to assess their potential to reduce substances that could contribute to estrogenic effects in male fish. The effluent from a conventional, activated sludge treatment line was compared to a similarly treated effluent with a final sand-filtering step. The addition of ozonation (15 g O₃/m³), a moving bed biofilm reactor (MBBR) or both in combination was also evaluated. There was also a separate treatment line that was based on a membrane bioreactor. A small battery of hepatic estrogen-responsive genes was measured in the exposed fish using quantitative PCR. Concentrations of steroid estrogens and estrogenic phenols in the effluents were measured by GC-ECNI-MS. The ozonated effluents were the only tested effluents for which all measured biological effects in exposed fish were removed. Chemical data suggested that the MBBR technology was equally effective in removing the analyzed estrogens; however, elevated expression of estrogen-responsive genes suggested that some estrogenic substances were still present in the effluent. The membrane bioreactor removed most of the measured estrogens and it reduced the induction of the estrogen-responsive genes. However, fish exposed to this effluent had significantly enlarged livers. Given that the same influent was treated in parallel with a broad set of technologies and that the chemical analyses were combined with an in vivo assessment of estrogenic responses, this study provides valuable input into the assessment of advanced treatment processes for removing estrogenic substances.     

Rapid effects of diverse toxic water pollutants on chlorophyll a fluorescence: variable responses among freshwater microalgae

Chlorophyll a fluorescence of microalgae is a compelling indicator of toxicity of dissolved water contaminants, because it is easily measured and responds rapidly. While different chl a fluorescence parameters have been examined, most studies have focused on single species and/or a narrow range of toxins. We assessed the utility of one chl a fluorescence parameter, the maximum quantum yield of PSII (F_v/F_m), for detecting effects of nine environmental pollutants from a range of toxin classes on 5 commonly found freshwater algal species, as well as the USEPA model species, Pseudokirchneriella subcapitata. F_v/F_m declined rapidly over <20 min in response to low concentrations of photosynthesis-specific herbicides Diuron^® and metribuzin (both <40 nM), atrazine (<460 nM) and terbuthylazine (<400 nM). However, F_v/F_m also responded rapidly and in a dose-dependent way to toxins glyphosate (<90 μM), and KCN (<1 mM) which have modes of action not specific to photosynthesis. F_v/F_m was insensitive to 30-40 μM insecticides methyl parathion, carbofuran and malathion. Algal species varied in their sensitivity to toxins. No single species was the most sensitive to all nine toxins, but for six toxins to which algal F_v/F_m responded significantly, the model species P. subcapitata was less sensitive than other taxa. In terms of suppression of F_v/F_m within 80 min, patterns of concentration-dependence differed among toxins; most showed Michaelis-Menten saturation kinetics, with half-saturation constant (K_m) values for the PSII inhibitors ranging from 0.14 μM for Diuron^® to 6.6 μM for terbuthylazine, compared with a K_m of 330 μM for KCN. Percent suppression of F_v/F_m by glyphosate increased exponentially with concentration. F_v/F_m provides a sensitive and easily-measured parameter for rapid and cost-effective detection of effects of many dissolved toxins. Field-portable fluorometers will facilitate field testing, however distinct responses between different species may complicate net F_v/F_m signal from a community.     

Long-term effects of elevated UV-B radiation on photosynthesis and ultrastructure of Eriophorum russeolum and Warnstorfia exannulata

The depletion of stratospheric ozone above the Arctic regions may increase the amount of UV-B radiation to which the northern ecosystems are exposed. In this paper, we examine the hypothesis that supplemental UV-B radiation may affect the growth rate and photosynthesis of boreal peatland plants and could thereby affect the carbon uptake of these ecosystems. In this study, we report the effects of 3-year exposure to elevated UV-B radiation (46% above ambient) on the photosynthetic performance and ultrastructure of a boreal sedge Eriophorum russeolum and a moss Warnstorfia exannulata. The experiment was conducted on a natural fen ecosystem at Sodankylä in northern Finland. The effects of UV-B radiation on the light response of E. russeolum CO₂ assimilation and the maximal photochemical efficiency of photosystem II in a dark-adapted state (F_v/F_m) were measured in the field. In addition, the effect of supplemental UV-B radiation on organelles of photosynthetic cells was studied by electron microscopy. The UV-B treatment had no effect on the CO₂ assimilation rate of either species, nor did it affect the structure of the cell organelles. On chlorophyll fluorescence, the UV-B exposure had only a temporary effect during the third exposure year. Our results suggested that in a natural ecosystem, even long-term exposure to reasonably elevated UV-B radiation levels does not affect the photosynthesis of peatland plants.     

Performance and influence of numerical sub-models on the CFD simulation of free and forced convection in double-glazed ventilated façades

Double-glazed façades (DGF) are an attractive option in contemporary architecture and are increasingly used in commercial buildings. They offer some advantages compared with single façade systems but require careful design. The solar-collector-like construction leads to high temperatures in the façade cavities and the possibility of the building overheating. This is undesirable effect, especially in Mediterranean climates. A possible solution for reducing thermal overheating is to use the air channel between the two layers of glass to evacuate the solar radiation absorbed by the façade. A suitable simulation procedure for modeling these façades would be very useful for designing buildings of this type.     

Microbial impact of small tributaries on water and shellfish quality in shallow coastal areas

This study aimed to investigate the impact of small tributaries on seawater and shellfish quality in coastal area subjected to brief episodes leading to fecal contamination. Escherichia coli and F-RNA-specific bacteriophages were selected as fecal indicators and astroviruses were chosen as being representative of pathogens in the human population during winter viral epidemics. A two-dimensional hydrodynamic model was built to simulate the current and dispersion in the model domain, which includes areas uncovered at low tide. The model also includes decay rates to simulate microorganism behavior and assess the influence of fecal input on shellfish quality. The originality lies in the fact that specific features of the study area were considered. Modeling results indicate limited particle movements and long flushing times at the back of the bay, where shellfish are farmed. Computational results showed that under normal conditions, i.e. 94% of the time, when rainfall was less than 10 mm per day, the sector shows acceptable water quality. These results are in agreement with shellfish concentration measured in the field. Under high flow conditions, high concentrations of fecal indicators and astrovirus were measured in the river and tributaries. The corresponding fluxes were over 50 times higher than under normal weather conditions. The location of the shellfish beds near the coast makes them vulnerable and fecal indicators and viruses were detected in shellfish after short rainfall events. Our modeling approach makes a contribution to shellfish management and consumer protection, by indicating the "risk period" as defined by EU regulations. Molecular development such as viral quantification in conjunction with model developments will help to prevent shellfish contamination and thus provide safer products to consumers and an effective tool for shellfish producers.     

In situ aquatic bioassessment of pesticides applied on rice fields using a microalga and daphnids

This study assessed the effects of episodic contamination on a drainage canal adjacent to an area of intensive rice production (Coimbra, Portugal). Four monitoring periods were considered [i) before herbicide application (day -14), ii) at the first application day (day 0), iii) 3 or 5 and iv) 6 days after]. Each one consisted in three complementary evaluation lines: a) physico-chemical analyses, b) whole effluent toxicity (WET) assays with Pseudokirchneriella subcapitata, c) in situ bioassays to assess microalgae (P. subcapitata) growth, and the feeding rate and survival of Daphnia longispina and Daphnia magna. Study sites were located upstream, in a protected wetland (L1), and downstream, in the vicinity of rice fields (L2). Along with the application of agrochemicals, there was a general decrease of the water quality, especially in L2, due to nutrient and herbicide inputs. Herbicide peaks (on days 0, 5 and 6) in L2 water samples were recorded concomitantly or immediately after their application. Regarding the in situ bioassessment, the algae growth decrease from day 0 onwards in L1, whilst in L2 its inhibition was generally coherent with the decline of the water quality. Apparently, WET tests indicated that the limitation of nutrients could be affecting algae growth in L1, however, conclusions should be cautious. The feeding depression of daphnids occurred on days 0 and 5 for D. longispina and only on day 0 for D. magna, while significant reductions on survival were restricted to day 0 for both species. The impairments occurring on day 0 were linked to a potential increased toxicity driven by the ingestion of particle-bound herbicides and suspended particles. The feeding rate of daphnids provided an earlier indication of toxic impairments, though it is prompted the use of complementary endpoints and trophic levels in order to understand the cumulative effects due to various herbicide pulses.     

Effect of river water, sediment and time on the toxicity and bioavailability of molinate to the marine bacterium Vibrio fischeri (Microtox)

The toxicity and bioavailability of molinate to Vibrio fischeri (Microtox((R))) were determined in both laboratory and river water in the absence and presence of sediment after 0, 24, 48, 72 and 96-h exposure. The bioavailability of molinate, expressed as 5min EC50s (bioluminescence) and their fiducial limits calculated using initial measured concentrations, to V. fischeri in laboratory water in the absence and presence of sediment ranged from 1.8 (1.7-2.1) to 3.6 (3.5-3.7) mgL(-1) and 1.3 (1.2-1.4) to 4.2 (3.5-4.5) mgL(-1), respectively. The corresponding values in river water and river water plus sediment were 1.7 (1.6-1.8) to 3.8 (3.6-4.1) and 1.3 (1.3-1.4) to 4.6 (4.2-4.9) mgL(-1), respectively. River water did not significantly (P>0.05) reduce the bioavailability of molinate to V. fischeri compared to that of laboratory water. However, the presence of sediment significantly (P<0.05) reduced the bioavailability of molinate to V. fischeri in both waters. The exposure time also significantly (P<0.05) reduced the bioavailability of molinate to V. fischeri in both waters in the presence and absence of sediment. The type of water did not significantly (P>0.05) affect the loss of molinate during the 96-h exposure period. However, the presence of sediment significantly (P<0.01) increased the loss of molinate from the test solutions, probably by binding to the sediment particles. Exposure period and concentration levels significantly (P<0.05) affected the loss of the herbicides over the 96h.     

Effects on growth, photosynthesis and pigments of the freshwater moss Fontinalis antipyretica Hedw. after exposure to wood ash solution

The application of wood ash from biofuel sources to the forest has been suggested as a source of nutrients for trees and for restoration of acidified soils and surface waters. Studies on the effects of wood ash on aquatic organisms and ecosystems are, however, few. This study investigated the effects of wood ash (0.1-10 g l(-1)) on the freshwater moss Fontinalis antipyretica Hedw., which has previously been shown to be a sensitive test organism for assessing environmental pollution. After nine weeks of treatment with wood ash, a significant effect of enhanced stem growth was observed at higher concentrations (1-10 g l(-1)). The concentration of wood ash was also correlated with the growth of secondary branches. Photosynthesis (oxygen evolution after 4 h of exposure to wood ash) was significantly lower in the alkaline treatments (no pH adjustment) compared to the treatments with neutral wood ash solutions (pH adjusted to 7.5). Furthermore, photosynthesis in the alkaline wood ash treatments was significantly lower compared to the control. The ratio between the optical density value before and after acidification (OD(665/665a)) was higher for all wood ash concentrations compared to the control. The OD(665/665a) values ranged from 1.52 to 1.61 and there was a difference, however not significant, between the alkaline and the neutral treatment at 10 g l(-1) wood ash. This study clearly demonstrated that wood ash may be beneficial for F. antipyretica at moderate concentrations (0.5-5 g l(-1)), particularly when a sudden increase in pH is avoided.     

The impact of selected water quality parameters on the inactivation of Bacillus subtilis spores by monochloramine and ozone

Selected water quality parameters-pH, dissolved organic carbon, turbidity (NTU), and temperature-were tested for their potential effects on ozone and monochloramine inactivation of Bacillus subtilis spores. In oxidant demand-free phosphate-buffer, temperature had the strongest influence on inactivation kinetics when using ozone, pH had a smaller but significant impact on B. subtilis spore inactivation with both monochloramine and ozone. Where monochloramine was applied, modeling and experimental measurements confirmed that dichloramine levels were too low to produce significant inactivation effects under these experimental conditions. It was demonstrated that oxidant demand-free phosphate buffer may not be an adequate environmental analogue for inactivation responses in natural waters.     

Microbiological surveillance of private water supplies in England - The impact of environmental and climate factors on water quality

A passive surveillance system captured information on 34,904 microbiological samples from 11,233 private drinking water supplies within England as well as the associated constructional, climatic and environmental variables. Escherichia coli was detected in 6588 (18.87%) of samples and at least one positive sample was detected from 3638 (32.39%) of sites. However, this estimate of supplies failing to meet the European drinking water E. coli standard was probably an underestimate as the more samples taken per supply, the more likely the supply was to fail. A multivariable model of private water supplies data showed a strong seasonal impact, with samples between January and May being significantly less contaminated with E. coli than samples between June and December. Samples from springs (OR 2.5, CI 2.0-3.1) or surface waters (OR 2.4, CI 0.8-7.0) were more likely to fail than groundwater sources, as were supplies with no effective treatment (OR1.8, CI 1.5-2.3). Commercial supplies were less likely to fail than domestic supplies (OR 0.63, CI 0.48-0.83) and the probability of failure was linearly associated with the density of sheep in the area and rainfall on the previous day. A Monte Carlo modelling approach was used to estimate that, had sufficient samples been taken, 54% (95% confidence intervals 49-59%) of all private water supplies in England were likely to be unsatisfactory. These findings will be able to inform risk assessments of private water supplies prior to microbiological results being available.     

The comparison of two heavy fuel oils in composition and weathering pattern, based on IR, GC-FID and GC-MS analyses: Application to the Prestige wreackage

This paper compares the weathering patterns of two similar fuel oils: a fuel oil spilled after a ship accident (Prestige-Nassau, off the Galician coast -NW Spain-) and a fuel designed to cope with the numerous quests for samples to carry out scientific studies (IFO). Comparative studies were made to evaluate the capability of common fingerprinting analytical techniques to differentiate the fuels, as well as their capabilities to monitor their weathering. The two products were spilled under controlled conditions during ca. four months to assess how they evolved on time. Mid-IR spectrometry and gas chromatography (flame ionization and mass spectrometry detectors) were used. IR indexes related to total aromaticity, type of substituents (branched or linear chains) and degree of aromatic substitution reflected well the differences between the fuels during weathering. Regarding the chromatographic measurements, the n-alkanes became highly reduced for both fuel oils and it was found that the PAHs of the synthetic fuel (IFO) were more resistant to weathering. Regarding biomarkers, the different profiles of the steranes, diasteranes and triaromatic steroids allowed for a simple differentiation amongst the two products. The %D2/P2 ratio differentiated both products whereas the %N3/P2 one ordered the samples according to the extent of their weathering.