Heavy PAHs Research Articles

Human Biomonitoring in the Oil Shale Industry Area in Estonia-Overview of Earlier Programmes and Future Perspectives.

Ida-Viru County, in Eastern Estonia, features industrially contaminated sites–where oil shale has been mined and used for electricity generation, and shale oil extraction. Higher prevalence of respiratory and cardiovascular disease has been found in the region due to high quantities of air pollution. Within the framework of “Studies of the health impact of the oil shale sector—SOHOS,” this analysis aimed to map earlier human biomonitoring (HBM) studies and identify the suitable biomarkers for upcoming HBM in Estonia. Altogether, three studies have been conducted among residents: first, among adults in the 1980's; second, among children in the 1990's; and third, among employees, with a focus on workers and miners in the oil shale chemistry industry in the late 1990's and 2000's. In some of those studies, increased levels of biomarkers in blood and urine (heavy metals, 1-OHP) have appeared; nevertheless, in last 20 years, there has been no population-wide HBM in Estonia. According to air pollution monitoring and emission analysis, the pollutants of concern are benzene, PM10, PM2.5, and PAHs. In general, there is a decreasing trend in air pollutant levels, with the exception of a slight increase in 2018. One of the aims of HBM is to be analyzed if this trend can be identified in HBM, using similar biomarkers as applied earlier. The future perspective HBM could be divided into two Tiers. Tier 1 should focus on exposure biomarkers as heavy metals, PAH, and BTEX metabolites and Tier 2, in later stage, on effect biomarkers as Ox LDL, TBARS, etc.

Evaluation of the biochar effect on co-contaminated soils by the fitotesting method

In the conditions of the adjacent location of agricultural land with industrial land, there is a continuous soil contamination of the territories adjacent to the emission sources. There is a threat of hazardous ecotoxicants migration, including heavy metals and benzo[a]pyrene, one of the main persistent compound, the marker of soil PAHs pollution, along trophic chains, which can be dangerous for a public health. In this study, the technology of biochar manufacturing from sunflower husks tested for improving the territories adjacent to technogenic emissions sources of heavy metals and PAHs. Using scanning electron microscopy showed that the resulting sorbent has a high specific surface area. With the help of phyto-testing, the optimal dose of the sorbent introduction into the combined contaminated soil was determined in the level of the 1% and 2%. The use of a sorbent in an amount of 1% significantly increased the root length of the test culture by 3.5 times as compared to the variant without adding the sorbent. The biochar applying into the contaminated soil contributed to an increase in the length of the barley root that confirms the effectively of the developed sorbent remediation of the co-contaminated soils.

Quantitative Assessment of Human Health Risks Based on Soil Heavy Metals and PAHs Sources:Take a Polluted Industrial Site of Beijing As an Example

In this study, 130 surface soil samples were collected at an industrial pollution site in Beijing and the contents of As, Be, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Ti, Zn, and 16 PAHs were determined. The positive matrix factorization (PMF) model was used to analyze the sources of heavy metals and PAHs, and the contributions of these sources to carcinogenic risk and hazard index in the study area were calculated. The results showed that the contents of Cd, Cu, Pb, Hg, As, Zn, and Cr in the soil exceeded the background values in different degrees; Cd, Hg, Pb, Zn, and Cu exceeded the background values by>50%. Low molecular weight PAHs (two and three rings) and high molecular weight PAHs (four to six rings) accounted for 39.6% and 60.4% of the total content of 16 PAHs. The PAH content at 77% of the sampling points at the target site was more than 1000 μg ·kg-1, which suggests severe PAH pollution at the site. Heavy metals Be, Ti, As, and Ni mainly originated from natural sources. There are three major sources of 7 heavy metals and 16 PAHs at the site: coal combustion (Hg and ∑16PAHs), smelting (Cu, Cr, Pb, and Zn), and traffic (Sb and Cd). The contribution rates of these sources to the total average contents of seven heavy metals and sixteen PAHs at 130 sampling sites were 8.46% (coal combustion), 90.61% (smelting), and 0.94% (traffic). Human health risk assessment results showed that the carcinogenic risk of seven heavy metals and ∑16PAHs ranged from 4.17×10-6 to 39.38×10-4, and the hazard index ranged from 0 to 32.23. The maximum carcinogenic risk and hazard index values were calculated near the coking plant. Benzo[α]pyrene was the PAH that posed the highest carcinogenic risk and Zn was the heavy metal that had the highest hazard index value. The average carcinogenic risk of coal combustion was 2.16×10-4, accounting for 50.26% of the total average carcinogenic risk. The average hazard index of smelting was 0.834, accounting for 56.43% of the total average non-carcinogenic risk. These two pollution sources are responsible for the high levels of heavy metals and PAHs in the soil of the steel smelting sites that pose the most severe health risks. The results of this study can provide reference for soil remediation and process optimization at other heavily polluted industrial sites.

Electrokinetical enhanced delivery of acidic potassium permanganate and removal of copper-pyrene compound pollution in a red soil

Soil contaminated by combinations of heavy metals and organic pollutants has become an increasingly prominent environmental issue. Developing efficient technologies to synchronously decontaminate such co-contaminated sites is challenging and imperative. In our previous study for the treatment of Copper (Cu) and pyrene contaminated soil, electrokinetics (EK) coupled acidic permanganate (PM) performed best for degradation of pyrene near the injection spot, but it unfortunately prevented the migration of Cu. In order to further enhance the removal efficiency of these contaminants, in this study, batch experiments were conducted to investigate the feasibility of delivering PM by EK under regular refreshment of acidoxidant along with amplification of voltage gradient. The results showed that PM can be transported from cathode to anode to S2 section (near the anode) with a slow mass transfer rate via electromigration and reversed electroosmotic flow, and further delivery was achieved when Cu and pyrene were coexisted. The reaction of pyrene with PM produced a lower soil pH condition, which was conductive to the transport of Cu, and the existence of Cu promoted the migration of PM. The coexistence of Cu and pyrene favored the removal efficiency of the pollutants, and 92.8% of Cu and 70.7% of pyrene were removed after 15dEK treatment. Thus, EK+acidic PM with regularly supplement of oxidant is appropriate to achieve complete mass depletion of heavy metals and PAHs, especially in low buffered soils.

Heavy Metals and PAHs in Meat, Milk, and Seafood From Augusta Area (Southern Italy): Contamination Levels, Dietary Intake, and Human Exposure Assessment.

Heavy metals and PAHs were measured in animal foodstuffs from Augusta-Melilli-Priolo area in order to evaluate the potential human health risk associated to their consumption. All heavy metals were detected in seafood products while most of them were <LOD in beef, pork and milks samples. Particularly, seafood products registered higher values of total arsenic (As), mercury (Hg) and lead (Pb) than other food categories, while beef and pork showed higher content of zinc (Zn). Cadmium (Cd) and Pb were below the tolerable limits reported by the European Union in foodstuffs (1) while mercury exceed the threshold value in seafood products. Among the PAHs, chrysene (Chr) was detected in all the terrestrial foodstuffs with higher concentrations found in raw milks. Small quantity of benz(a)anthracene (BaA) were also found in this food. The health risk for consumers was assessed for five age categories of consumers calculating the estimated weekly intake (EWI), the target hazard quotient (THQ) and the cancer risk (CR) for each contaminant. Moreover, the margin of exposure (MOE) was estimated for PAHs. The EWIHg related to seafood products intake exceeded the Provisional Tolerable Weekly Intake (PTWI) recommended by the European Food Safety Authority. The THQHg was >1 for baby, children and teenagers, indicating a non-carcinogenic risk for these age categories by seafood ingestion. The CRAs overcame 1*10−5 for almost age categories (except “baby”) and for elderly, by seafood and beef ingestions respectively. Moreover, the MOE for PAHs showed a certain cancer risk for “baby” related to cow milk ingestion.

Effects of Elevated Concentrations of Co-Existing Heavy Metals and PAHs in Soil on Phytoremediation

Abstract This study presents a series of laboratory experiments conducted to investigate the effects of elevated contaminant concentrations on phytoremediation of soils with mixed contaminants. A s...

Recycling contaminated marine sediments as filling materials by pilot scale stabilization/solidification with lime, organoclay and activated carbon

Nowadays, stabilization/solidification (S/S) applied to the treatment of contaminated marine sediments (CMSs) represents a key technology for the production of new materials for civil engineering. Literature has shown the feasibility of CMSs recycling, although sediment needs pre-treatments for the removal of organic matter and to improve the mechanical properties of the product post S/S. In view of the full-scale applicability where it is essential to reduce any additional phase (i.e., pre-treatments), this study is aimed at demonstrating the technical feasibility of recycling CMSs as filling materials by S/S treatments with lime, organoclay and activated carbon. The original sediments are contaminated with heavy metals, PCBs, and PAHs, exceeding limits values prescribed by law. Different mixtures were tested on the STABSOL-P pilot scale plant. The absence of specific CMSs pre-treatments resulted in failure to comply with the 28-days leaching test only for copper; greater air curing with 56-days allowed it to be complied with for all the investigated metals. The organic contamination, while slowing down the process of chemical stabilization, allowed in any case to get a product environmentally compatible. The unconfined compression strength tests showed values (>28 kPa) that would allow potential CMSs recycling for environmental enhancement. The mass balance of the case study of the Mar Piccolo of Taranto (Southern Italy) showed potential recycling of marine sediments (the production of 974 kg filling materials per 1000 kg of dredged sediment) with a consequent missed disposal in landfills of 0.65 m3/1000 kg of sediment.

Phytotoxicity and phytogenotoxicity of soil and air in the vicinity of a petrochemical plant in P\u0142ock (Poland)

Petrochemical industries have been widely recognised as important emission sources of airborne contaminants including heavy metals and polycyclic aromatic hydrocarbons PAHs, which affect the quality of air, soil and vegetation. In this study, our aim was to examine the phytotoxicity and phytogenotoxicity of soils and air in the vicinity of a petrochemical plant, in order to assess the potential threat of such industrial objects for crops and natural vegetation, in the cases when the allowable concentrations of contaminants are not exceeded and the plants in the vicinity visually do not seem to be affected. For phytotoxicity and phytogenotoxicity assessment, the Phytotoxkit and respectively Vicia RTA and TRAD MCN bioassays were used. According to our results, in spite of relatively low content of heavy metals and PAHs (hardly any exceedance of standards), the phytotoxicity and especially phytogenotoxicity of soil samples collected up to 18 km from the refinery were detected by the bioindicators. The phytogenotoxicity of air was also indicated within the distance of up to 12 km. We concluded that to obtain the complete view of the environmental risks in a surveyed area, a combination of chemical analysis of environmental samples with the bioindication methods should be implemented. In addition, setting the acceptable levels of contaminants should involve a more extensive use of bioindication methods (especially genotoxicity assessment).

Current status of coastal sediments contamination in the former industrial area of Bagnoli-Coroglio (Naples, Italy)

ABSTRACT The purpose of this study is to investigate the current status of contamination due to the heavy metal and organic substances (PAHs, HC >12, organotin compounds, PCB, DDD, DDE, DDT) pollution of the sediments from the coastal area of the Bagnoli brownfield (Naples, Italy) and draw some hypotheses on the origin and trends of industrial and also geogenic contamination. Surface sediments and cores were collected and analysed. The results showed remarkable concentrations of heavy metals, PAHs, and other substances that are significantly higher than the national guideline values of sea sediment quality. Correlation analyses and spatial distribution analyses showed that generally the inorganic and organic pollutants have similar patterns, confirming the common origin from the industrial activity, but also that some of the studied metals have some natural contribution originated from the geologic setting of the area. The distribution of most of the heavy metals (especially Cd, Hg, Pb, Cu, Zn, partially Cr and Ni) and PAHs are similar, and the highest concentrations were recognised between and just off the piers, but a diffuse contamination is widespread up to the external areas of the site perimeter, rising concern on the diffusion of contaminants to the whole Gulf of Pozzuoli.

Gasification of pellets produced from blends of biomass wastes and refuse derived fuel chars

Refuse derived fuel (RDF) was carbonized at 300 °C for 30 min and the resulting RDF char was used as additive for biomass pellets. Pine waste pellets with 0, 5 and 10% incorporation of RDF char were prepared and characterized. RDF char incorporation caused an increase in fixed carbon and ash contents of the pellets. The pellets were subjected to gasification in a 1 kg/h bubbling-fluidized-bed gasifier at different temperatures (800 and 850 °C) and equivalence ratios (0.25 and 0.30). The producer gas yield varied from 1.5 to 2.5 m3/kg and was higher for an ER of 0.25. Carbon conversion and cold gas efficiency presented values between 60.4% - 96.1% and 42.3%-73.7%, respectively. Concentrations of CO, CO2, H2 and CH4 reached values between 13.3-17.4 vol% dry for CO, 13.1-14.7 vol% dry for CO2, 4.9-11.1 vol% dry for H2 and 3.5-4.4 vol% dry for CH4. Tars produced during gasification contained mainly aromatic hydrocarbons and phenols, showing an increase in heavy PAHs concentration with higher RDF char incorporation. The RDF char can be used as a gasification additive at moderate incorporation ratios.

Effect of manure and mineral fertilisers on the content of light and heavy polycyclic aromatic hydrocarbons in soil

A study was conducted to explore the effects of fertilisation with farmyard manure (FYM) and mineral fertilisers on the content of PAHs in soil. The analyses were made on soil samples (collected in 1998–2009) from a long-term field experiment set up in 1986 in Bałcyny near Ostróda. The content of light and heavy polycyclic aromatic hydrocarbons was determined on a gas chromatograph coupled with an FID detector. The analytical data were processed statistically according to an analysis of variance with repeated measurements. The content of light and heavy polycyclic aromatic hydrocarbons was significantly higher in soil fertilised with FYM than in soil nourished only with mineral fertilisers. The effect of increasing doses of potassium on total light PAHs in soil depended on a fertilisation system – there was either a distinct decrease in soil fertilised with mineral substances alone or a slight increase in soil fertilised with manure. Regular soil liming significantly raised the ∑ of heavy PAHs in soil treated with manure but significantly decreased it in soil supplied only mineral fertilisers.

An integrated assessment of the long-term impact of municipal sewage sludge on the chemical and biological properties of soil

The aim of the study was to assess the long-term changes of chemical and biological properties of soil treated with various application rates of municipal sewage sludge (SS) under the condition of field and laboratory experiments. The experiment scheme included five treatments: 1 – the control; 2 – 10 t of SS dry matter per hectare; 3 – 20 t of SS dry matter per hectare; 4 – 40 t of SS dry matter per hectare and 5 – 60 t of SS dry matter per hectare. Considerable dose-dependent enhancement of carbon and nitrogen contents as well as enzyme activities were observed, particularly when high rates of sewage sludge were applied. It was proven that such rates allowing for longer durability of favorable changes in the soil and did not pose risks for its quality in the context of heavy metal and PAH concentrations as well as enzymatic activity. The presence of Phalaris arundinacea plants had a positive impact on the chemical properties and biological condition of soil, expressed in the lower content of heavy metals and PAHs and higher activity of soil enzymes. Significant correlations between all analyzed parameters in the field and laboratory experiment indicates that such studies allow a reliable assessment of the impact of SS application on the chemical and biological condition of soils within a given ecosystem.

Two-Year Monitoring of PAH in the Soils and Pleurozium schreberi under the Impact of Coal Mining

We surveyed PAH concentrations in soils and moss Pleurozium schreberi (Wild. ex. Brid.) Mitt. in the Bolshezemelskaya tundra at the sites affected by coal mining and compared them to the control ecosystems. The samples were collected during 2013–2015 at the distances 0.5, 1 and 1.5 km from the coal mine. During the study period, PAH content in mosses decreased 3 times and PAH content in soils was almost the same. Mass fraction of PAH in soils was stable at different distances from the coal mine. Content of heavy PAH in soils was high near the mine. In Pleurozium schreberi, PAH content decreased when the distance from the coal mine increased. Statistically significant correlations have been found between PAH content in soil and moss due to the fact that Pleurozium schreberi is the main part of vegetation cover and forms upper soil horizons. Diagnostic indexes calculated for PAHs ratios in soil and moss have revealed petrogenic origin of PAH at the control site and at the distances 1 and 1.5 km from the mine. At the distance 0.5 km from the coal mine, PAH content was determined by pyrogenic factor due to motor road. PAH percent proportions were stable over time both in soils and mosses, which suggested the permanence of the main polyarenes sources during the study period.

Effects of temperature on the chemical composition of tars produced from the gasification of coconut and palm kernel shells using downdraft fixed-bed reactor

Tar is derived from the gasification of cellulose and hemicellulose-rich coconut shell (CS) and lignin rich-palm kernel shell (PKS) using a downdraft fixed-bed reactor at 700 °C–900 °C. The tar yields and higher heating values from both biomass decrease with the increase in temperature, but high tar yields and higher heating values are obtained from PKS. Fourier transform infrared showed a similar pattern between the wavenumbers of 1500 cm−1 and 4000 cm−1, thereby indicating that the main chemical groups in CS and PKS tars are similar. The ultraviolet–visible spectroscopy shows that the aromatic content of tars increases with the increase in temperature, and CS tars show higher fluorescence intensity than PKS tars at >800 °C. Proton nuclear magnetic resonance shows that the tars from CS and PKS exhibit highly aromatic and phenolic protons, respectively. Gas chromatography–mass spectrometry results reveal that the total relative content of compounds in PKS tars is slightly higher than that in CS tars, and phenol group is the most abundant compound at all temperatures. Overall, the formation of aromatics and light PAHs are higher with CS tars, but PKS tars are more stable for the formation of heterocyclic and heavy PAHs.

Analysis results of in situ water and sediment quality of Újpest backwater

Water is one of the most significant and vulnerable natural resources. The aim of our study presented here was to assess the sediment and water quality of Újpest backwater and its main influencing factors. The study area is located in the north side of Budapest, a backwater of the Danube river. An industrial region of the city, also serving as recreational area for nearby residents. The average water depth is 4,5 meters and the length of the backwater is 2200 meters. The most significant economic activity is the ship-building and maintenance. In order to assess water and sediment quality, a number of physical, chemical and the microbiological measurements were carried out on both water and sediment samples. The water samples were collected at two dates, while sediments samples were taken at one date in 2015. Sediment analysis included heavy metals (Cu, Zn, Pb, Cd), TPH and PAH measurements. Water quality analysis included chemical (NH3, NH4+, NO3-, Fe, pH value, conductivity, dissolved oxygen) and microbiological parameters. The results of the study showed that the sediment contained different types of heavy metals and hydrocarbons due to the industrial activities and transportation. During the analyses, we measured high Pb, Cd, Cu, Zn, TPH and PAH concentration in the northern part of the backwater. Possible reasons of the high values include ship maintenance and repairing, ship traffic and road traffic. Measured high Pb, Cd, TPH and PAH concentrations in the sediment might carry environmental risks. Among the general water quality parameters, we found high Fe concentrations mist likely connected to railway traffic in the northern part of the sampling area, while microbial analysis showed only acceptable or lower counts.

Physico-Chemical Properties of Soil Sourced from Automobile Mechanic Workshop in Ikoku Mechanic Village, Mile 3 Diobu, Port Harcourt, Rivers State, Nigeria

This study investigated the impacts of automobile mechanic workshops on the concentrations of PAHs, T.H.C, T.O.C, pH, EC, Cations, heavy metal and particle size distribution in urban soil sourced from automobile workshops in Ikoku mechanic village, Mile 3 Diobu, Port Harcourt, Rivers state. Six samples were collected at sites of close proximity to the selected automobile workshops (Experimental sites) and sites that are far away from the workshop without the influence of automobile mechanic activities (control sites). The levels of Zinc (Zn), lead (Pb), Chromium (Cr) and cadmium (Cd) were determined using atomic absorption spectrophotometer (AAS), the PAHs were determined using GC-FID and GC-MS. The levels of T.O.C and T.H.C were determined using Titration method and Genesis 10 UV spectrometer, the pH and EC were determined using Pre-calibrated pH and EC meters, the Particle Size Distribution was determined by Sieve analysis method. Data interpretation involved the use of descriptive statistics for test of significant variation in the levels of heavy metals, Physico-chemicals and PAHs between the experimental sites and control site. Findings revealed that concentrations of Heavy metals, PAHs, T.H.C, T.O.C, EC and Cations were generally higher in soils under the influence of automobile mechanic workshop activities than sites with no such influence. The mean values of Pb, Zn, Cr and Cd were 32.94, 74.17, 5.35 and 2.86mg/kg respectively in soils under the influence of automobile mechanic activities and 32.52, 100.69, 10.09 and 3.68mg/kg respectively in soils with no such influence. The mean concentrations of PAHs, T.H.C, T.O.C, EC, pH and Cations as compared to those of the Control sites are 332.35 to 65.28, 2.47 to 1.94, 36.20 to 22.35, 273.2 to 119.7, 7.145 to 7.245 and 30.52 to 42.99 respectively. There were significant variations in the levels of PAHs, Heavy metals and the Physico- chemical parameters between the experimental sites and the control sites. The Particle Size Distribution revealed that the soil is of low permeability thus limiting the degree of seepage and supporting more accumulation of the contaminants at the top soil. It is recommended that mechanic villages should be sited far from residential areas, Quick remediation of polluted soil using various remediation methods should be encouraged and continuous education and training should be provided for the automobile workers, emphasizing on the environmental implications of their poor occupational waste management.

Comparison of Primary Volatiles from Coal and Biomass Pyrolysis in N2 and CO2

The present work compares the primary tars produced by fast pyrolysis in nitrogen (N2) and carbon dioxide (CO2) atmospheres of coal (bituminous colombian coal), raw biomasses (straw and walnut shells), and biomass macromolecules (cellulose, hemicellulose, and lignin). Primary tars have been obtained in a heated strip reactor (HSR). Particles are heated to temperatures of 1573 and 2073 K with a heating rate of 104K/s; meanwhile, the gas in the reactor is kept at near ambient temperature. Therefore, volatiles ejected from the hot particles are quenched immediately after volatilization, minimizing secondary reactions. Chemicophysical analyses, such as gas chromatography–mass spectrometry (GC–MS), size-exclusion chromatography (SEC), and ultraviolet–visible (UV–vis) spectroscopy, have been performed to detect the compounds present in primary tars. Anhydrosugars (levoglucosan) largely dominate the primary tars of cellulose and hemicellulose. Lignin primary tars are instead mainly composed of oxo-aromatics (vanillin and benzendiol). The chemical composition of tars from fast pyrolysis of two natural biomasses (walnut shells and straw) cannot be obtained as a linear combination of the chemical composition of the tars produced from pyrolysis of single lignocellulosic components. First of all, no anhydrosugars are present. Phenols and benzofurans prevail in straw tars, while benzendiols and some compounds related to the lignin structure (vanillin and cinnamaldehyde) prevail in tars of walnut shells. At the higher temperature, the results drastically change: oxygenated aromatic compounds are present in the form of naphtalenols rather than benzendiols, and larger amounts of heavy polycyclic aromatic hydrocarbons (PAHs, indenopyrene and benzofluorantene) appear. The primary tars of coal pyrolysis are very different from those of biomass: heavy aliphatics (C21–C30) are the most abundant class at 1573 K. At 2073 K, large amounts of heavy PAHs (benzophenanthrene and benzopyrene) are produced. A table is provided with the indication of the main components of primary tars, which can be of interest for the development and validation of pyrolysis models for coal and biomass.

Indoor environmental quality classification of school environments by monitoring PM and CO2 concentration levels

Nowadays the control of indoor healthiness and comfort has become a key issue in school environments. Indoor environment quality (IEQ) as regards indoor air quality (IAQ), ventilation requirement as well as health effects assessed by Hazard Index and Cancer Risk were investigated in a naturally ventilated school by monitoring indoor/outdoor CO2 concentrations and particulate matter (PM) levels. This way, a CO2 fluxes balance permitted to calculate actual ventilation rates used to classify the classrooms on the basis of the proposal contained in fpEN 16,798 standard. The relationship between ventilation, CO2 levels and PM was also studied. In absence of appreciable internal pollution sources, the indoor concentrations of chemical pollutants were correlated to the corresponding outdoor concentrations by the comparison of indoor/outdoor PM whose differences in this case depend only by indoor deposit and resuspension. Heavy metals (As, Cd, Ni, Pb) and PAHs were considered as required by CEN recommendations. A simple procedure was carried on to assess the potential health hazards of pollutants on students. Hazard Index and the total Cancer Risk of the inhalation exposure were evaluated as proposed by United States Environmental Protection Agency. The calculated values resulted normally acceptable if related to daily school period, but not completely satisfactory because they highlighted that the indoor contaminant concentrations were not acceptable for 24 h exposure. Therefore these chemical pollutants reduce the no health hazard exposure capacity of the children in the remaining part of the day.

Composition and abundance of microplastics in surface sediments and their interaction with sedimentary heavy metals, PAHs and TPH (total petroleum hydrocarbons)

Abstract The composition and abundance of microplastics (MPs) and concentrations of heavy metals, PAHs and TPH in surface sediments as well as their relationship with the number of MPs in three contrasting sediment types were investigated in Bandar Abbas, Iran. Total number of MPs ranged from 3542 to 33561 items per m2 in different stations. The collected MPs displayed a variety of shapes and colors. White filaments were the most dominant MP item in the Khor-e-Yekshabeh and Suru stations while blue fragments were dominant items in the Gorsozan. Concentrations of heavy metals, PAHs and TPH also varied among stations. There were significant correlations between the total number of MPs, sediment grain size and ten measured heavy metals (P 0.05). MPs in sediment as vectors for heavy metals and some PAHs can ingest by benthic animals, resulting in their bioaccumulation in marine food web.

Screening of polycyclic aromatic hydrocarbon degrading bacterial isolates from oil refinery wastewater and detection of conjugative plasmids in polycyclic aromatic hydrocarbon tolerant and multi-metal resistant bacteria

Wastewater were collected from the effluent channel in the vicinity of Mathura oil refinery, U.P. (India) and analysed for physicochemical characteristics, heavy metals as well as organic compounds including PAHs. The interaction of PAHs and heavy metals with various group of microorganisms revealed the viable count of aerobic heterotrophs, asymbiotic nitrogen fixers, actinomycetes and fungi were found to be 2.38 × 106, 1.89 × 104, 2.20 × 104 CFU/mL and 8.76 × 103 CFU/mL respectively. We have selected and screened 50 bacterial isolates for their resistance/tolerance to heavy metal and PAHs. Out of 25 multi-metal resistant isolates, 6 were able to tolerate PAHs at the concentration of 5000 μg/mL (50μg/disc) to naphthalene, anthracene, phenanthrene and pyrene. The PAH degradation efficiency of the isolates was assessed using spectrophotometer with 100 μg/mL of phenanthrene and observed different degree of degradation ranging from 34-66% after 96 h of incubation. One of the bacterial isolates KWB3 (identified as Enterobacter ludwigii by 16S rDNA sequencing) exhibited maximum degradation efficiency (66%) was further tested for phenanthrene degrading ability in the presence and absence of a co-substrate (glucose) in a mineral salt medium; and a number of metabolites were produced and detected by GC-MS which revealed the presence of benzocoumarin, phthalic acid, catechol and several low molecular weight compounds. The DNA derived from multi-metal and PAHs tolerant bacteria were PCR amplified using Inc specific primers and positive PCR products were obtained with oriT and trfA2 of the IncP group; indicates that these bacteria have gene-mobilizing capacity.