Contaminated Sediment Samples Research Articles

Occurrence and spatial distribution of microplastics in water and sediments of Hatiya Island, Bangladesh and their risk assessment

This research has evaluated the MPs distribution, characteristics, and potential threats of MPs in surface water and sediments from Hatiya Island. The results showed that the abundance of MPs was 139 ± 44 items/m3 in surface water and 493 ± 80 items/kg dw in sediments, indicating higher levels of MPs contamination in sediment samples. Fibers were the predominant kind of microplastics, and microscopic sizes (0.3–1.5 mm) MPs were generally more frequent and largely present in both the surface water and sediments. Fourier-transform infrared spectroscopy (FTIR) confirmed that polyethylene terephthalate was the major polymer component of microplastics in surface water, whereas polyethylene was the most abundant polymer in sediments. MPs contamination risk was examined based on multiple risk assessment models. Nemerow pollution index (NPI) and pollutant load index (PLI) show minimal pollution levels of MPs. But potential hazard index (PHI), potential ecological risk factor (Er), and potential ecological risk index (RI), indicate severe MPs contamination due to the presence of polyurethane, polycarbonate, polyvinyl chloride, epoxy that were hazardous MPs and exhibited a critical concern for MPs risk. These statistics will help to understand the environmental difficulties generated by MPs and which hazard is waiting for mankind in the future.

Microplastic contamination in bathing areas in the Central Amazon, Itacoatiara, Brazil.

Due to the visible abundance of plastic improperly disposed of in the environment, the number of investigations has increased worldwide in different water bodies and biota. Despite this, studies of contamination by microplastics in freshwater environments in the Amazon are scarce. This study investigated microplastic contamination in sediment samples of bathing areas in the Central Amazon, in Itacoatiara, Amazonas, Brazil. A total of 202 microplastic particles were recorded in the five investigated areas that are used for recreation. These results indicate no significant difference in the number of microplastic particles among the establishments; however, the size of the microplastic particles differed significantly between the establishments. Both blue and red microplastic particles were recorded, with blue particles being the most abundant. The microplastic particles were in the form of fibers and fragments. The number of microplastic particles was significantly different between the areas within and adjacent to the bathing areas, though the size of the microplastic particles was not significantly different in the areas within and adjacent to the bathing areas. There was no significant correlation in the establishments in regard to their frequency of use and contamination (number of microplastic particles). This is the first study that indicates the anthropogenic impacts associated with microplastic contamination in recreation areas within the Amazon Forest, an area considered by the world to be of vital importance for conservation. The results of this study indicate that microplastics are present in these bathing areas of the Central Amazon and that contamination in areas used for recreation may be significantly higher than in areas not used for this purpose.

Ecological Risk Assessment and Source Contributions of Heavy Metals in the Sediment of the Chan Thnal Reservoir, Kampong Speu, Cambodia

Metal contamination from farming, inadequate wastewater treatment, and poor disposal of municipal garbage are major threats to public health. This research aimed to (1) assess the extent of heavy metal contamination in sediment samples, (2) describe the distribution of heavy metals by locating likely pollution sources using a positive matrix factorization (PMF) model, and (3) quantify the potential ecological consequences associated with these metals at six different places around the Chan Thnal Reservoir. The findings indicated steady degradation and suggested moderate to high metal contamination. Fe > Zn > Cr > Cu > Pb > Co > As > Mn > Cd was the trend of metal concentrations in the sediment. Various soil pollution indices showed that most of the studied sediment samples were clean, moderately clean, or slightly contaminated. However, Co and Cd reached high-risk conditions posing a severe problem to the local population living in and around the Chan Thnal Reservoir. Principal component analysis (PCA) was used to estimate primary factors in PMF analysis. It was found that the contamination of As, Cu, Zn, Cd, and Pb originated from agricultural and traffic vehicle sources; however, Zn, Fe, Mn, Cr, and Cu were derived from natural sources (e.g., atmospheric deposition and compost amendment). Furthermore, Fe, Cd, Mn, Co, Pb, and Cr were generated from urban and industrial sources (metal coatings, plastic burning, wastewater irrigation, and sewage sludge). Accordingly, this research improves our knowledge of the prevalence of heavy metal pollution in agroecosystems, which may be used to foresee and mitigate the risks of heavy metal exposure to humans and other organisms.

Bottom-Up Evaluation of the Uncertainty of the Quantification of Microplastics Contamination in Sediment Samples.

The quantification and comparison of microplastic contamination of sediments are affected by sample heterogeneity and the systematic and random effects affecting sample analysis. The quantification and combination of these components in the measurement uncertainty allows the objective interpretation of analysis results. This work presents the first detailed evaluation of the uncertainty of microplastic contamination quantification in sediments. The random and systematic effects affecting microplastic counts are modeled by the Poisson-lognormal distribution with inputs estimated from duplicate sediment analysis and the analysis of sediments spiked with microparticles. The uncertainty from particle counting was combined with the uncertainty from the determination of the dry mass of the analytical portion by the Monte Carlo method. The developed methodology was implemented in a user-friendly spreadsheet made available as the Supporting Information. The contamination of sediment samples collected in various inland Portuguese waters was determined, ranging from [0; 160] to [361; 2932] kg-1 for a 99% confidence level, and compared by assessing if the difference between contamination levels is equivalent to zero for the same confidence level. Several samples proved to have metrologically different microplastic contamination. This work represents a contribution to the objectivity of the assessment of environmental contamination with microplastics.

Effects of bio-chemo-mechanical processes on the properties of contaminated marine sediments

A detailed multi-scale investigation of the geotechnical, chemical and mineralogical properties was conducted on contaminated sediment samples collected within the Mar Piccolo, a marine basin in the south of Italy. The basin is located close to one of the most important industrial sites in Europe, which has also been declared ‘at high risk of environmental crisis’ and prioritised for remediation activities. A multidisciplinary investigation campaign showed that the samples collected close to the sea floor are characterised by high values of both heavy metals and organic pollutants and by the presence of significant amount of organic matter. Several samples in the top layer exhibited peculiar geotechnical properties, in terms of plasticity and activity indexes, compressibility and hydraulic permeability. While the prime suspect for such unconventional behaviour was chemo-mechanical coupling between the soil skeleton and contaminants, it turned out that the biogeochemical degradation of organic matter and the presence of microfossils and diatoms is likely to affect significantly the micro to macro behaviour of polluted marine sediments.

Prioritizing Suitable Quality Assurance and Control Standards to Reduce Laboratory Airborne Microfibre Contamination in Sediment Samples

The ubiquity and distribution of microplastics, particularly microfibres, in outdoor and indoor environments makes it challenging when assessing and controlling background contamination, as atmospheric particles can be unintentionally introduced into a sample during laboratory analysis. As such, an intra-laboratory examination and literature review was completed to quantify background contamination in sediment samples, in addition to comparing reported quality assurance and control (QA/QC) protocols in 50 studies examining microplastics in sediment from 2010 to 2021. The intra-lab analysis prioritizes negative controls, placing procedural blanks in various working labs designed to prepare, process, and microscopically analyse microplastics in sediment. All four labs are subject to microfibre contamination; however, following the addition of alternative clean-air devices (microscope enclosure and HEPA air purifiers), contamination decreased by 66% in laboratory B, and 70% in laboratory C. A review of microplastic studies suggests that 82% are not including or reporting alternative clean-air devices in their QA/QC approaches. These studies are found to be at greater risk of secondary contamination, as 72% of them ranked as medium to high contamination risk. It is imperative that laboratories incorporate matrix-specific QA/QC approaches to minimize false positives and improve transparency and harmonization across studies.

Physical-chemical characterization of uranium containing sediments

The presented paper is intended to study the chemical behaviour of combined geogenicanthropogenic uranium content in specific stream sediments. The sampling points have been chosen with respect to the natural conditions in the locality of groundwater outflow from a former uranium mine adit in Považský Inovec mountain range, near Kálnica village. Besides the total uranium determination and physical-chemical characterization of the relevant water- and sediment samples we carried out modified Tessier type sequential fractionation extractions of natural- and artificially contaminated sediment samples after time dependent agitation in air and in the atmosphere of argon. The obtained results have been compared with those fulfilled with montmorillonite K-10. The total uranium concentrations of the relevant groundwater samples as well as of stream sediments have been determined by ICP-MS using HP 4500. The determinations of uranium in extracts have been accomplished according STN757614, utilizing arsenazo III as a selective complex forming reagent for spectrophotometric determination of uranyl-ions at 650 nm. The total uranium concentration of the groundwater outflow and in the sediment taken in its immediate vicinity has been 31.75±0.35 μg dm-3 and 38.0±2.7 μg g-1 respectively. Unlike montmorillonit K-10, in which the carbonate-bound fraction of uranium after 1 week aeration and agitation in argon atmosphere represents 22.8% and 18.6% respectively, uranium in investigated sediments has been present predominantly in carbonate-bound fraction-reaching under similar conditions 38.6% and 26.6%, respectively.

An Assessment of Heavy Metal Contamination in the Nakdong River Around the Weir

In this study, the concentrations and characteristics of copper (Cu), zinc (Zn), and lead (Pb) contamination in sediment samples were investigated using aqua regia extraction and Tessier’s five-step sequential extraction. Based on the concentration of metals, the influence of the Hapcheon-Changnyeong weir on sediments in the Nakdong River was assessed. The origins of the contaminants, their bioavailability, and their mobility were determined using sequential extraction. Greater concentrations of heavy metals were found in samples collected closer to the weir. The largest proportion of Cu was identified in the residual fraction based on sequential extraction, whereas Zn was predominantly found in the reducible fraction. Iron-manganese in the reducible fraction of Zn has the potential to leach back to the water body. In addition, the combined concentration of fractions 1 and 2 of Cu comprised more than 20% of total amount that still has potential to affect the water quality. The results of this study were compared with existing sediment standards set out by the NIER (National Institute of Environmental Research), Canada, and US EPA (United States Environmental Protection Agency) guidelines, as well as the risk assessment code (RAC). The concentrations of heavy metals exceeded the standards set by the Canadian guideline by up to four times in particular samples, highlighting the need for continual monitoring.

Bioremediation perspective of historically contaminated sediment with polycyclic aromatic hydrocarbons

The purpose of the current study is to compare the influence of different aerobic conditions (biostimulation (BS), bioaugmentation (BA), and a combination of biostimulation and bioaugmentation (BB)) on polycyclic aromatic hydrocarbons (PAH) degradation and compare the degraded amount with single step XAD-4 extraction as a new tool for bioavailability assessment for chronically contaminated sediment samples obtained from territory of Autonomous Province Vojvodina of Serbia (S1, S2, and S3). A great number of papers dealing with biodegradation of PAHs in spiked sediment or soil have been published, but to the authors’ knowledge, a limited number of papers studied aged, historically polluted sediment and a sum of chosen U.S. Environmental Protection Agency (USEPA) PAHs. A significant reduction (up to 67%) in PAH concentration was observed, while the percentage of reduction varied depending on the sediment sample and treatment used. BS treatment successfully stimulated growth of indigenous bacteria. Further, PAH-degrading strain Sphingomonas paucimobilis F8 inoculated in BA and BB treatment survived for up to 7 weeks after it was suppressed by unfavorable conditions or native microbes. Degraded amounts generally showed good correlation with results obtained from XAD-4 extraction. Results obtained in the current study represent a good start for standardizing a XAD-4 extraction technique as a simplified, easier, and lower cost method for bioavailability assessment.

Ultrasound-assisted and disposable pipette extraction for the determination of faecal contaminants in sediment samples by GC-MS

ABSTRACT Given the amount of untreated sewage released into the environment and possible consequences, new methodologies are required for the detection and quantification of potential pollutants found in sediment samples, including faecal contamination. Solid matrix extraction methodologies (e.g. Soxhlet extraction) are generally laborious and require the use of large amounts of solvents, which is inconsistent with the principles of green chemistry. In this study,a simple, robust and efficient analytical method for the determination of faecal sterols in sediment samples using ultrasound-assisted extraction (UAE) followed by pre-concentration with disposable pipette extraction (DPX) was developed. Multivariate experimental designs were used for the optimisation of the extraction parameters for the UAE and DPX procedures. The separation and detection of the analytes were conducted by GC-MS. Dichloromethane was used as the extraction solvent in the UAE. The DPX procedure was conducted applying 5 cycles of extraction with 700 µL of sample (10 s each) and 2 cycles of desorption with 200 µL of solvent (20 s each). The optimised desorption solvent was a mixture composed of ethyl acetate:acetonitrile (60:40 v/v). The limits of detection were 7.6 µg kg−1 for cholesterol and 75 µg kg−1 for cholestanol, coprostanol and stigmasterol and the limits of quantification were 25 µg kg−1 for cholesterol and 250 µg kg−1 for the other analytes. Relative recovery was evaluated for 3 levels of concentration and the results ranged from 78% to 114%. The precision was evaluated through intra-day (n = 3) and inter-day (n = 9) tests, and the ranges observed were 0.5–10%and 2–16%, respectively. The results demonstrate that this effective and fast method shows potential for the determination of faecal contaminants in sediments.

Coupled Application of Antioxidant Defense Response and Embryo Development in Amphipod Crustaceans in the Assessment of Sediment Toxicity.

Survival rate, frequency of malformed embryos, and antioxidant defense system responses in the benthic amphipod Gmelinoides fasciatus from the Baltic Sea were measured to examine the effects of toxic sediments, and to assess the usefulness of these endpoints in sediment toxicity biotesting. A highly contaminated sediment sample from the Baltic Sea was diluted with sediment from a clean site to come up with a series of 5 test sediments with dilutions from 1:32 to 1:1024, and the reference sediment. The 1:32 dilution of the test sediment was analyzed for organotins (2862 µg tin [Sn] kg dry wt -1 ), polycyclic aromatic hydrocarbons (6064 µg kg dry wt -1 ), and selected trace metals (e.g., copper 352 mg kg dry wt -1 ). The survival rate of G. fasciatus (10-d toxicity test) was 100% in the reference and 1:1024 treatments, and began to decline from the 1:256 dilution onward. In a 28-d experiment, various types of morphological malformations were observed in 11 to 80% of the amphipod embryos in the 1:64, 1:128, and 1:256 dilutions, with only <5% in the reference treatment. Also, elevated activities in the antioxidant defense system enzymes glutathione S-transferase and catalase were observed in amphipods exposed to the contaminated sediments compared with the reference treatment, with responses at lower contamination levels compared with the appearance of malformations in the embryos. The results obtained illustrate the effectiveness of the combined application of embryonic malformations and antioxidant defense system biomarkers in amphipods in the assessment of sediment toxicity, and potentially also of sublethal effects of chemical contamination in aquatic ecosystems. Environ Toxicol Chem 2019;38:2020-2031. © 2019 SETAC.

Isolation and characterization of microorganisms of Ejamah-Ebubu oil spill site

The study was designed to evaluate the bacterial diversity of crude oil contaminated site. Sediments samples collected at different georeferenced sampling point; Nwata A, Nwata B, Nwata 3, Ochani and Eyeyaro in Ejamah-Ebubu were analyzed for microbiological and biochemical qualities using the basic biological method. Our results show that the total aerobic heterotrophic bacteria (HUB) of the five sampling points range from 1.0x105 - 1.7x106cfu/g. Total aerobic hydrocarbon utilizing bacteria (HUB) range from 1.0x10 4- 7.2x105cfu/g while sulphate reducing bacteria (SRB) ranged between 2.2x104-1.6x105 cell/ml. Careful phenotypic and biochemical test revealed twenty oil degrader belonging to five genera; Bacilus, Citrobacter, Micrococcus, Enterobacter and Pseudomonas . The frequency of occurrence of the microbial isolate revealed Bacillus (40%), Citrobacter, (25%) Pseudomonas (15%), Enterobacter and Micrococcus (10%) . This study indicates that the contaminated sediment samples contain a diverse population of oil degrading bacteria and the use of sediment-associated microorganism has the potential for bioremediation of crude oil contaminated sites. Keywords : Georeferenced, crude oil, diversity, Bacillus, sulphate reducing bacteria

Study of physicochemical changes of polluted sediments from Reconquista river basin (Argentina) after remediation processes

The physicochemical properties of sediments and their ability to retain pollutants are affected by both contamination and remediation processes. The aim of this study is to determine structural and physicochemical changes in real sediment contaminated with metals, subjected to bioleaching processes in a previous study. The sediment contaminated with heavy metals and samples of the same sediment treated with different heap leaching tests were used. They were characterised by potentiometric titrations, electrophoretic mobility, organic matter (OM), nuclear magnetic resonance (NMR), volatile solids and sulphides. For contaminated and treated sediment samples, the results of OM, sulphides, volatile solids to 600°, potentiometric titrations and zeta potential values depended on the bioleaching treatment performed previously. The contaminated sediment sample without any bioleaching treatment presented the greatest amount of OM and sulphides. Moreover, metal adsorption isotherms were performed. The contaminated sediment without bioleaching treatment was the one with the highest adsorption capacity. The baseline sample did not present a noticeable adsorption capacity. This study indicates the importance of the contribution of OM and sulphides to sediments and structural and physicochemical studies after remediation treatments.

Study of physicochemical changes of polluted sediments from Reconquista river basin (Argentina) after remediation processes

The physicochemical properties of sediments and their ability to retain pollutants are affected by both contamination and remediation processes. The aim of this study is to determine structural and physicochemical changes in real sediment contaminated with metals, subjected to bioleaching processes in a previous study. The sediment contaminated with heavy metals and samples of the same sediment treated with different heap leaching tests were used. They were characterised by potentiometric titrations, electrophoretic mobility, organic matter (OM), nuclear magnetic resonance (NMR), volatile solids and sulphides. For contaminated and treated sediment samples, the results of OM, sulphides, volatile solids to 600°, potentiometric titrations and zeta potential values depended on the bioleaching treatment performed previously. The contaminated sediment sample without any bioleaching treatment presented the greatest amount of OM and sulphides. Moreover, metal adsorption isotherms were performed. The contaminated sediment without bioleaching treatment was the one with the highest adsorption capacity. The baseline sample did not present a noticeable adsorption capacity. This study indicates the importance of the contribution of OM and sulphides to sediments and structural and physicochemical studies after remediation treatments.

SugE belongs to the small multidrug resistance (SMR) protein family involved in tributyltin (TBT) biodegradation and bioremediation by alkaliphilic Stenotrophomonas chelatiphaga HS2

Tributyltin (TBT) used in a variety of industrial processes, subsequent discharge into the environment, its fate, toxicity and human exposure are topics of current concern. TBT degradation by alkaliphilic bacteria may be a key factor in the remediation of TBT in high pH contaminated sites. In this study, Stenotrophomonas chelatiphaga HS2 were isolated and identified from TBT contaminated site in Mediterranean Sea. S. chelatiphaga HS2 has vigor capability to transform TBT into dibutyltin and monobutyltin (DBT and MBT) at pH 9 and 7% NaCl (w/v). A gene was amplified and characterized from strain HS2 as SugE protein belongs to SMR protein family, a reverse transcription polymerase chain reaction analysis confirmed that SugE protein involved in the TBT degradation by HS2 strain. TBT bioremediation was investigated in stimulated TBT contaminated sediment samples (pH 9) using S chelatiphaga HS2 in association with E. coli BL21 (DE3)-pET28a(+)-sugE instead of S chelatiphaga HS2 alone reduced significantly the TBT half-life from 12d to 5d, although no TBT degradation appeared using E. coli BL21 (DE3)-pET28a(+)-sugE alone. This finding indicated that SugE gene increased the rate and degraded amount of TBT and is necessary in enhancing TBT bioremediation.

Bioremediation of PCB-contaminated shallow river sediments: The efficacy of biodegradation using individual bacterial strains and their consortia

Elimination of dangerous toxic and hydrophobic chlorinated aromatic compounds, mainly PCBs from the environment, is one of the most important aims of the environmental biotechnologies. In this work, biodegradation of an industrial mixture of PCBs (Delor 103, equivalent to Aroclor 1242) was performed using bacterial consortia composed of four bacterial strains isolated from the historically PCB-contaminated sediments and characterized as Achromobacter xylosoxidans, Stenotrophomonas maltophilia, Ochrobactrum anthropi and Rhodococcus ruber. The objective of this research was to determine the biodegradation ability of the individual strains and artificially prepared consortia composed of two or three bacterial strains mentioned above. Based on the growth parameters, six consortia were constructed and inoculated into the historically contaminated sediment samples collected in the efflux canal of Chemko Strážske plant – the former producer of the industrial mixtures of PCBs. The efficacy of the biotreatment, namely bioaugmentation, was evaluated by determination of ecotoxicity of treated and non-treated sediments. The most effective consortia were those containing the strain R. ruber. In the combination with A. xylosoxidans, the biodegradation of the sum of the indicator congeners was 85% and in the combination with S. maltophilia nearly 80%, with inocula applied in the ratio 1:1 in both cases. Consortium containing the strain R. ruber and S. maltophilia showed pronounced degradation of the highly chlorinated PCB congeners. Among the consortia composed of three bacterial strains, only that consisting of O. anthropi, R. ruber and A. xylosoxidans showed higher biodegradation (73%). All created consortia significally reduced the toxicity of the contaminated sediment.

Fate and biodegradability potential of an emerging micropollutant diclofenac in subsurface environment

The present study deals with the assessment of the fate of an emerging contaminant (diclofenac), present in the subsurface environment at specific concentration levels, and its biodegradation potential under different environmental configurations. Diclofenac is a widely consumed nonsteroidal anti-inflammatory drug used as a painkiller prescribed as pills or ointments and among the most frequently detected pharmaceuticals in wastewater treatment plants’ effluents. Fermentative/methanogenic cultures were enriched from previously contaminated sediment samples. Although partial biodegradation was achieved in all enrichment cultures, complete degradation was not observed. The results reflected that less than 6% of the diclofenac sorbed on the solid phase and the rest was either biotransformed (25–40%) or remained in the liquid phase (55–70%) at the end of 45-day incubation period. Although partial cometabolic degradation of diclofenac occurred in the presence of glucose, biodegradation was not observed in the presence of readily biodegradable carbon source (i.e., acetate). Diclofenac concentration up to 1000 µg/L did not affect the methanogenic activity of the enriched culture. The results of this study will have a significant impact in the designation of the permitted concentration limits of diclofenac before the discharge through wastewater treatment plants.

Pollution and ecological risk assessment of heavy metals in the soil-plant system and the sediment-water column around a former Pb/Zn-mining area in NE Morocco

This study discussed the environmental fate and ecological hazards of heavy metals in the soil-plant system and sediment-water column around the former Pb-Zn mining Zeïda district, in Northeastern Morocco. Spatial distribution, pollution indices, and cluster analysis were applied for assessing Pb, Zn, As, Cu and Cd pollution levels and risks. The geo-accumulation index (Igeo) was determined using two different geochemical backgrounds: i) the commonly used upper crust values, ii) local geochemical background calculated with exploratory data analysis. The soils in the vicinity of the tailings, as well as the sediments downstream of the latter, displayed much higher metal concentrations, Igeo, and potential ecology risk coefficient values than other sites, classifying these sites as highly contaminated and severely hazardous. The concentrations of Pb in contaminated sediment samples also exceeded the PEC limits and are expected to cause harmful effects on sediment-dwelling organisms. Based on the comparison with the toxicity limits, the most contaminated plant samples were found around the tailings piles. The metal concentrations in both raw and filtrated water samples were overall below the drinking water standards in samples upstream and downstream of the mining center, indicating that heavy metals levels in the Moulouya River surface waters were not affected by the tailings spill. Cluster analysis suggest that: i) Pb and Zn in sediments were derived from the abandoned tailings and are mainly stored and transported as particle-bound to the bedload, ii) Pb, Zn, and Cu in the soil-plant system were related to the dispersion of tailings materials while As and Cd originated primarily from natural geological background in both the soil-plant and the water-sediment systems.

Isolation and characterization of PAH-degrading bacteria from the Eastern Province, Saudi Arabia

Contaminated sediment samples were collected from the Eastern Province, Saudi Arabia for isolation of pyrene- and phenanthrene-degrading bacteria by enrichment method. Four isolates were morphologically characterized as Gram-negative rod strains and 16S rRNA sequence analysis revealed the isolates as closely related to Pseudomonas aeruginosa, P. citronellolis, Ochrobactrum intermedium and Cupriavidus taiwanensis. Degradation of the polycyclic aromatic hydrocarbons (PAHs) by the latter three strains was investigated in liquid cultures. Results of concentration reduction analyzed with gas chromatography show that P. citronellolis_LB was efficient in removing phenanthrene, degrading 94% of 100ppm in 15days while O. intermedium_BC1 was more efficient in pyrene-removal, degrading 62% in 2weeks. Furthermore, bacterial growth assessment using optical density and population counts revealed the latter as more suitable for microbial growth analysis in PAH-containing cultures. In conclusion, the isolated bacterial strains could be further developed for efficient use in biodegradation of PAH.

Filamentous Fungi Isolates of Contaminated Sediment in the Amazon Region with the Potential for Benzo(a)pyrene Degradation

Filamentous fungi were isolated from contaminated sediment samples in the Amazon region of Brazil to select species with potential for benzo(a)pyrene (BaP) degradation, a polycyclic aromatic hydrocarbon (PAH) with high molecular weight and known for its mutagenic and carcinogenic properties. The isolates were submitted to biodegradability test using 2.6-dichlorophenol indophenol (DCPIP), gallic acid reaction, and evaluation of BaP influence in the enzymatic (ligninolytic) activity. The selected fungi were submitted to the taxonomic identification and used in biodegradation assays, which were carried out using gas chromatography coupled to mass spectrometry (GC-MS). A qualitative analysis of the presence of BaP metabolites that have recently been reported in literature was also performed by GC-MS. A total of 146 fungal isolates were recovered. Among them, 63.7 % were positive for the redox indicator DCPIP. From these isolates, 22.6 % showed positive responses to the gallic acid reaction. In enzymatic tests, the fungi Megasporoporia sp. S47 and unidentified Sordariales S69 presented highest activities of laccase and manganese peroxidase in the presence of BaP. Additionally, the white-rot fungus Megasporoporia sp. S47 showed better performance in BaP degradation (54 %). Therefore, Megasporoporia sp. S47, obtained from an environment with considerable PAH contamination, was selected as a promising genetic resource for application in new studies related to enzyme production and characterization and BaP degradation optimization.