Polychlorinated Biphenyls In Soil Research Articles

Concentrations and risks of PCBs in soil contaminated with transformer oil in selected locations in Warri South Local Government Area, Delta State, Nigeria

According to the list of persistent organic pollutants (POP), polychlorinated biphenyls (PCBs) are a class of organic substances whose usage has been outlawed in the majority of nations. In addition to been used in paint, flame retardants, plasticizers, and lubricants, they were principally employed in transformers, capacitors, and other industrial purpose. PCBs have been found everywhere over the world because they are capable of being released into the environment through primary and secondary sources, travel over great distances in the atmosphere and are thus persistent. PCBs were examined in soil from area around transformer installations at several sites in Warri South Local Government Area (LGA), Delta State, Nigeria. Using Agilent 6975 GC-MS at three different locations, the evaluation was conducted for both total PCBs and congeners. The soil samples were cleaned with column chromatography using silica gel and hexane as the eluting solvent and extracted with a 1:1 hexane-acetone solution in an ultrasonic bath. With the following results recorded - Ubeji (0.148 ± 0.019 mg/kg), Ogunu (0.531 ± 0.063 mg/kg) and Edjeba (0.415 ± 0.34 mg/kg), the assessment demonstrate that all locations were polluted with PCBs that were below the maximum limit of 2.0 mg/kg as allowed by the United States Toxic Substance Control Act (USTSCA). The total cancer risk calculated in these chosen locations corresponds to Ubeji (5.41×10−7), Ogunu (1.95×10−6) and Edjeba (1.52×10−6). This result showed that all the locations assessed have very low to low cancer risks compared with the value advised by USTSCA.

The Spatial Distribution and Potential Risk Assessment of POPs in Farmland around a Typical E-Waste Dismantling Site.

Pollution from electronic-waste (E-waste) dismantling is of great concern. This study investigated the concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs) in 253 cropland soil samples around an abandoned E-waste dismantling site in Taizhou city, Zhejiang province in China, using an analytical method which simultaneously extracted, purified and determined the identity and quantity of the three types of persistent organic pollutants. Meanwhile, their spatial distributions, pollution characteristics, and risk assessments were further analyzed. Total PCBs in the test soils ranged from below method detection limits (ND) to 2985.25μgkg-1 on a dry weight basis (d.w.), and the spatial distribution indicated a "hot spot" of PCBs pollution in the study area. The PAHs were detected in all samples with total concentrations ranging from 4.99 to 2723.06μgkg-1d.w. The distribution of PBDEs showed the pollution characteristics of "family-run workshops", with a total content range of ND ~ 899.34μgkg-1d.w., of which BDE209 was typically the dominant congener, accounting for 74.05% of the total PBDEs content in the test soils, with the highest content reaching 857.72μgkg-1d.w. Results showed that the ecological and lifetime carcinogenic risks of PCBs and PAHs were low in the study area, but the health risk caused by oral ingestion and dermal contact accounted for the highest proportion of the total exposure risks, while inhalation could be ignored. PBDEs in soils of the study area were a potential chronic non-carcinogenic risk, particularly for children. Therefore, in order to protect human health and environment, it is necessary to regulate the management of E-waste dismantling sites and pollution control.

Spatio-Temporal Variations, Fugacity Fractions and Air-Soil Exchanges of PCBs in Industrial, Urban and Semi-Rural Sites

This study investigated the spatiotemporal variations in the occurrence of polychlorinated biphenyl (PCB) congeners both in soil and ambient air. Soil and air samples were taken simultaneously for three seasons (spring, summer, and autumn) from industrial, urban, and semi-rural areas in Bursa, Turkey. Light and medium PCB homologous groups were dominant in all samples. Total PCB (∑25 PCBs) concentrations in the air were 0.12 ± 0.13, 0.06 ± 0.07, and 0.08 ± 0.11 ng/m3 and in soil were 4.01.±2.38, 5.44 ± 3.14, and 3.66 ± 1.56 ng/g DM for summer, spring, and winter, respectively. Moreover, the samples were taken from different sites to determine the spatial fluctuations. The average ∑25 PCBs in the air were 0.22 ± 0.06, 0.03 ± 0.01, and 0.03 ± 0.02 ng/m3 and in soil were 7.08 ± 1.84, 2.98 ± 0.52, and 3.06 ± 0.70 ng/g DM for industrial, urban and semi-rural sites, respectively. Maximum air and soil PCB concentrations were determined in the industrial region. The spatiotemporal changes in the fugacity fractions and net fluxes were also examined. The direction of the PCB movement was assessed and the results indicated that soil was a diffusive source for PCBs. The calculated fugacity fractions (ff) were above 0.7 while average flux values were calculated as 0.65 ± 0.33 ng/m2-d, 0.21 ± 0.19 ng/m2-d, and 0.26 ± 0.27 ng/m2-day for industrial, urban and semi-rural regions, respectively.

The derivation of soil generic assessment criteria for polychlorinated biphenyls under the agricultural land scenario in Pearl and Yangtze River Delta regions, China

The agricultural soils in China are suffered from serious polychlorinated biphenyls (PCBs) contamination, however, the valid management standards for farmland are absent to efficiently control the health risks of PCBs exposure. This study analyzed the contamination characteristics and main composition of PCBs in agricultural soils of the southeastern China from the published literature over the past 20 years, and derived the regional generic assessment criteria (GAC) using an exposure modelling approach for individual and total PCBs (∑PCBs) via multiple exposure pathways such as ingestion of soil and dust, consumption of vegetables, dermal contact with soil and dust, ingestion of soil attached to vegetables, and inhalation of soil vapour and soil-derived dust outdoors under the agricultural land scenario. It is identified that the averaged ∑PCBs concentration of 80.03 ng g−1 under the 95 % lower confidence limit with an unacceptable health risk of 4.8 × 10−6 has significantly exceeded the integrated generic assessment criteria (expressed as GACint) of 16.5 ng g−1. Accordingly, the exposure pathways from the consumption of agricultural produces and indirect ingestion of soil attached to vegetables contributed up to 62 %–88 % of the total exposure, followed by 11 %–33 % of the soil ingestion and 2 %–6 % of dermal contact. The derived GACint for ∑PCBs is extremely valuable to effectively assess and manage the PCBs contamination in agricultural soils of China.

Status, distribution, source, and risk of polychlorinated biphenyl levels in soils of five cities from the Hexi Corridor, Northwest China

Few studies have been performed on the persistent organic pollutant contamination in soil from the plateau and remote areas, particularly the mid-latitude arid and semi-arid regions of Northwest China. The occurrence, spatial distribution, source, and potential risk of 12 polychlorinated biphenyls (PCBs) were investigated in soil collected from five Hexi Corridor cities in Northwest China. All of the PCBs were detected individually in the soil samples. The concentration of Σ12PCBs in the Hexi Corridor ranged from 2.0 to 148.5ng/g, with an average of 21.3ng/g. The tetra-CBs and hexa-CBs were the dominant PCB components in the soil. Higher PCB levels were found in the industrial city of Jiuquan, and the fewest PCBs were detected at Jinchang. Source analysis by principal component analysis showed that the dominant sources of PCBs were automobile exhaust, paint additives, insulation materials, and other industrial products. The carcinogenic health risk of PCBs in the Hexi Corridor soil was within acceptable levels, but the exposure risk of PCBs in soil for children was higher than that for adults.

Temporal Variations of PCBs and Their Estimated Air-Soil Exchange Fluxes Measured in Seven Sites in Bursa-Turkey

ABSTRACT Polychlorinated biphenyls (PCBs) can travel in ambient air for long distances and exchange between different environments. Soil and ambient air samples were simultaneously gathered during the winter and summer months in 7 regions in Bursa, Turkey, to study spatio-temporal fluctuations and soil-air exchange of PCBs. Σ25 PCB concentrations for the winter and summer seasons were 0.007–0.04 ng/m3 and 0.03–0.24 ng/m3 in air, also 4.09–10.00 ng/g DM and 1.65–10.01 ng/g DM in soil, respectively. PCB concentrations showed spatial variations in air and soil samples. The lowest total PCB levels were measured both in air and soil samples in the R (rural) site. The highest Σ25 PCB concentrations were measured in the SR3 site in soil samples, while the I1 site was the most polluted in air samples. Ambient air concentrations of PCBs in the summer months were greater than those in winter. In SR1, SR2, SR3, and I1 sites, soil PCB levels in the summer were higher than in the winter. The opposite was observed in the other sites (R, U, I2). Net flux values and fugacity fraction (ff) values for all regions indicated that PCBs represented a transfer from soil to air. The air-soil net gas phase flux values changed between 0.04 - 1.01 ng/m2-day and 0.02–0.83 ng/m2-day in the summer and winter, respectively. The PCB homologous distributions of mean flux values differed depending on the regions and seasons. PCBs with 4- and 5-CBs were dominant in both seasons.

Technological Developments and Remediation Mechanisms for Phytoremediation of PCB-Contaminated Soils

Polychlorinated biphenyls (PCBs) have been detected in a variety of environmental media, and they have been continuously introduced into the environment for industrial reasons, despite their harmful impact upon ecological health. Considering the adverse effects of PCBs, many researchers have begun to analyze remediation technologies for PCB-contaminated soil. In this study, the rise and fall of PCBs, as well as their physical and chemical properties and environmental impact, were reviewed. The pollution status of PCBs in soil was summarized. Based on the analysis and comparison of various remediation technologies, the limitations of several phytoremediation technologies in PCB-contaminated soils were analyzed. The influencing factors and transformation mechanisms of the phytoremediation of PCB-contaminated soil were investigated, and the research direction of enhancing the degradation of PCBs through the use of plants was also discussed.

Application of the gas-chromatographic analysis method for the characterization of oils in high capacity industrial electrical equipment

The article aims to highlight one of the highest environmental issues, caused by pollution with persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs). This form of environmental pollution with a negative impact on human health would not be possible without the use of high voltage industrial electrical equipment with dielectric fluids infested with various PCB isomers. In order to carry out the experimental program, samples of dielectric fluids both from Romania and Indonesia were investigated. The PCBs-containing samples were characterized using GC-ECD technique, employing an Agilent 7890 gas chromatograph equipped with a 15 mCi 63Ni µECD detector. PCBs concentrations were calculated using the standard calibration method based on the internal standard according to the corresponding normative documents. Ongoing work is carried out to adapt the technique for the analysis of PCBs in soils contaminated with oil products.

The concentrations and sources of PAHs and PCBs in soil from an oil field and estuary in the Yellow River Delta, China

The occurrence of organic pollutants [i.e. polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)] had been assessed in the soil samples collected from two sub-regions (an oil field and the Yellow River Estuary) in the Yellow River Delta (YRD), China. The concentrations of PAHs and PCBs in the soil were in the range of 157.8–481.7 μg kg−1 (dry weight) and 5.6–56.6 μg kg−1 (dry weight), respectively. The average concentration of PAHs in the soil samples from the oil field were 274.0 μg kg−1, and that in the estuary soil samples were 244.4 μg kg−1. The average concentration of PCBs in the soil samples from the oil field and the estuary were 24.2 μg kg−1 and 10.8 μg kg−1, respectively. The contribution of low molecular weight PAHs (two-ring and three-ring PAHs) was larger in the soil samples from the oil field than that in the estuary soil samples. Both PAHs and PCBs contaminations in the estuary area were lower than that in the oil field area. By using diagnostic ratios analysis, the main source of PAHs was attributed to petroleum input caused by the fuel oil or light refined petroleum products in the Gudong Oilfield. The amount of low-chlorine congeners (three to four chlorine atoms) PCBs in soil samples from the oil field were higher than that in the estuary soil samples. The congeners analysis of PCBs and the correlation analysis between the concentrations of PAHs and PCBs were employed. The results indicated that the emission of PCBs in YRD were influenced by both Gudong oilfield and other industrial sources.

Spatial distribution and ecological risks of polychlorinated biphenyls in a river basin affected by traditional and emerging electronic waste recycling in South China

With development of e-waste related legislation in China, formal recycling activities are designated in some areas while informal ones are illegally transferred to emerging areas to avoid supervision. However, the resulting environmental impact and ecological risks are not clear. Here, we investigated the discharge of polychlorinated biphenyls (PCBs) to soil and aquatic environments by e-waste recycling activities in the Lian River Basin, China. The study area included a designated industrial park in the traditional e-waste recycling area (Guiyu, known as the world's largest e-waste center), several emerging informal recycling zones, and their surrounding areas and coastal area. A total of 27 PCBs were analyzed, and the highest concentration was found in an emerging site for soil (354 ng g−1) and in a traditional site for sediment (1350 ng g‐−1) respectively. The pollution levels were significantly higher in both the traditional and emerging recycling areas than in their respective upstream countryside areas (p = 0.0356 and 0.0179, respectively). Source analysis revealed that the traditional and emerging areas had similar PCB sources mainly associated with three PCB technical mixtures manufactured in Japan (KC600) and the USA (Aroclor 1260 and Aroclor 1262). The PCB pollution in their downstream areas including the coastal area was evidently affected by the formal and informal recycling activities through river runoff. The ecological risk assessments showed that PCBs in soils and sediments in the Lian River Basin could cause adverse ecotoxicological consequences to humans and aquatic organisms.

Chlorine substitution-dependent toxicities of polychlorinated biphenyls to the earthworm Eisenia fetida in soil

Polychlorinated biphenyls (PCBs) with different chlorine substitution patterns often coexist in e-waste-processing sites. However, the single and combined toxicity of PCBs to soil organisms and the influence of chlorine substitution patterns remain largely unknown. Herein, we evaluated the distinct in vivo toxicity of PCB28 (a trichlorinated PCB), PCB52 (a tetrachlorinated PCB), PCB101 (a pentachlorinated PCB), and their mixture to earthworm Eisenia fetida in soil, and looked into the underlining mechanisms in an in vitro test using coelomocytes. After a 28-days exposure, all PCBs (up to 10 mg/kg) were not fatal to earthworms, but could induce intestinal histopathological changes and microbial community alterations in the drilosphere system, along with a significant weight loss. Notably, pentachlorinated PCBs with a low bioaccumulation ability showed greater inhibitory effects on the growth of earthworm than lowly chlorinated PCBs, suggesting that bioaccumulation was not the main determinant of chlorine substitution-dependent toxicity. Furthermore, in vitro assays showed that the highly chlorinated PCBs induced a high-percentage apoptosis of eleocytes in the coelomocytes and significantly activated antioxidant enzymes, indicating that the distinct cellular vulnerability to lowly/highly chlorinated PCBs was the main contributor to the PCBs toxicity. These findings emphasize the specific advantage of using earthworms in the control of lowly chlorinated PCBs in soil due to their high tolerance and accumulation ability.

Polychlorinated biphenyls (PCBs) in soils from typical paddy fields of China: Occurrence, influencing factors and human health risks

The contamination of paddy soils is of great concern since it links to human health via food supply. Limited knowledge is available on PCB residue characteristics and the associated health risks in paddy soils under various environmental conditions. In this study, a soil sampling campaign was conducted in three typical paddy fields, i.e., Sanjiang Plain (SP), Taihu Plain (TP) and Hani Terrace (HT), crossing a transect of 4000 km in China. The concentrations of 29 quantified PCBs varied from 58.6 to 1930 pg/g in paddy soils, with samples at TP showing the highest burden. Tri-CBs were the major homologue group at SP and HT, whereas hexa-CBs at TP. Altitude, temperature, soil organic matter content and soil conductivity well explained the variations in PCB concentrations among sites. The homologue profiles of soil PCBs followed the fractionation theory. In addition, soil conductivity was found to be negatively correlated to low-chlorinated PCBs and positively to high-chlorinated congeners. Furthermore, the toxicities of soil PCBs and the exposure risks through rice intake were estimated. Higher toxicity equivalent quantities and hazard indexes were found at SP than TP and HT, with over one third of the samples displaying health risks. The results of this work highlight the necessity to better understand the occurrence characteristics and the associated health risks of PCBs in soils of rice-growing regions.

An environmental friendly and stable analytical method for the determination of indicator polychlorinated biphenyls (PCBs) in solid and waste oil samples by gas chromatography-electron capture detector (GC-ECD)

This study presents the optimization and comprehensive verification studies of a stable analytical method for the determination of seven indicator polychlorinated biphenyls (PCBs) in solid and waste oil samples by using gas chromatography-electron capture detector (GC-ECD). In extraction method optimization, the maximum efficient and environmentally compatible extraction conditions were obtained at 30 mL hexane:acetone (3:1) use and 1.25 min solvent hold time. In validation studies, this method indicated an excellent linearity from 50 μg/L to 500 μg/L since the correlation coefficients higher than 0.9975 for all PCBs. The LOD values varied from 10.1 μg/L to 10.3 μg/L and the LOQ values ranged from 33.7 μg/L to 45.5 μg/L. The mean recoveries in soil, sewage sludge and waste oil varied as 85.6–97.7 %, 82.8–91.2 %, and 96.2–108.8 %, respectively. The intra-day precision (RSD, (%) in soil, sewage sludge and waste oil varied as 3.73–6.33 %, 3.72–8.91 %, and 1.37–5.44 %, respectively, whereas the inter-day precision (RSD, (%)) in sewage sludge changed from 2.35 to 9.74 %. In trueness, both results from CRMs (the recovery of PCBs varied 84.3 % to 114.4 %) and PTs (z-scores for indicator PCBs varied from (−0.5 to 1.65) demonstrate that this method possesses well enough and sufficient capability for the rapid, selective, and correct determination of indicator PCBs in soil and waste oil samples. There was no critical ME (recovery varied from 82.6 to 99.5 % in all matrices) and the RSD (%) values for each matrices was below 6 %. In the measurement uncertainty, the expanded uncertainties (µg/kg) of seven indicator PCBs changed from 3.50 to 4.38. The contributions from the sample preparation (45.19–53.83 %), the calibration curve (20.34–27.04 %) and the repeatability (11.80–18.02 %) were the major sources to the expanded uncertainty. In real samples, eleven sewage sludge, two soil, and twenty-seven waste oil samples had results above the LOQ for at least one indicator PCB.

Biological Remediation of Polychlorinated Biphenyl (PCB)-Contaminated Soil Using the Vermicomposting Technology for the Management of Sewage Sludge Containing Eisenia fetida Earthworms

ABSTRACT Biological vermicomposting is an economic and eco-friendly method to remove PCBs from contaminated soils. This study aimed to investigate the effects of biological sewage sludge on contaminated soil in the presence of Eisenia fetida earthworms for the removal of PCBs. For this purpose, different mixtures of contaminated soil and biological sludge were prepared at various mixing ratios in sample containers, followed by the addition of earthworms. The degradation period was 80 days. During the degradation process, the PCBs concentrations, C/N ratio, temperature, and number of earthworms were measured. The highest reduction in PCBs (47.4%) was found in vermicompost pilot D at a contaminated soil-to-biological sludge volume ratio of 1:4, where the PCBs concentration decreased from 18 mg/kg to 9.5 mg/kg. In the control pilot D, which was identical to the vermicompost pilot D, but lacked the earthworms, the removal rate was 34%. This means that earthworms have played an effective role in increasing the removal rate. Degradation mainly occurred by microorganisms; the earthworms increased the degradation efficiency by increasing contact between microorganisms and contaminants. Overall, the vermicomposting process, in which biological sewage sludge is used for feeding E. fetida earthworms to reduce the amount of PCBs in contaminated soil, can be introduced as an innovative approach. The present study proposed a practical method to manage soil PCB contamination, using available and cost-effective raw materials that can be used in a large scale in situ. The present results indicated that the use of biological sludge, in the presence of E. fetida earthworms, could reduce highly chlorinated PCB contamination in soils.

Pollution Characteristics and Health Risk Assessment of Polychlorinated Biphenyls in E-waste Disposal Residue-Soil-Vegetable

To study the characteristics of polychlorinated biphenyls (PCBs) in waste residue-soil-vegetable in an e-waste dismantling area and the potential health risks to humans, three samples of e-waste residue were collected, and 10 and 18 samples were taken from farmland soil and vegetables (six lettuce, six green bean, and six cabbage samples), respectively, next to the waste residue. High-resolution gas chromatography-mass spectrometry was used to detect the content of PCBs in waste residue, soil, and vegetables. The results showed that the total PCBs levels were as follows:waste residue (11938 ng·g-1, dw) > soil (45.54 ng·g-1, dw) > vegetables (11.51 ng·g-1, dw). The bio-sediment/soil enrichment factor values were as follows:lettuce samples (0.18) > green bean samples (0.05) > cabbage samples (0.01). There were 37 PCB identical homologues detected in the waste residue and soil, and 33 types were detected in vegetables, all of which were within the homologues detected in the waste residue and soil. Some homologues in the soil were correlated with cabbages (P<0.05). The column chart of PCB chlorination number in waste residues, soil, and vegetables showed that low-chlorinated biphenyls from trichlorobiphenyl to pentachlorobiphenyl mass fraction accounted for the largest proportion, accounting for 77.92%, 59.73%, and 73.96%, respectively. The proportion in the soil was relatively low, with the overall proportion showing a downward trend with increasing rate of chlorine generation. The results of the health risk assessment showed that the total HQ of PCBs in the soil and vegetables exposed to adults (male/female) and children was less than 1, which was at an acceptable level. The total CR of PCBs in the soil and vegetables exposed to adults (male/female) and children all exceeded 1×10-6, which is at an unacceptable level, and the values for adults (male/female) were higher than those for children.

Enhanced plant-microbe remediation of PCBs in soil using enzyme modification technique combined with molecular docking and molecular dynamics.

The study on the enhanced mechanisms of the enzymes involved in plant absorption, plant degradation, and microbial mineralization in the remediation of soils contaminated with polychlorinated biphenyls (PCBs) is of great significance for the application of plant-microbe combined remediation technique in PCB-contaminated soils. The present study first used a combination of molecular docking and molecular dynamics methods to calculate the effects of the plant absorption enzyme, plant degradation enzyme, and microbial mineralization enzyme on the PCBs in the soil environment. A multifunctional plant degradation enzyme was constructed with three functional roles of absorption, degradation, and mineralization using amino acid sequence recombination and site-directed mutagenesis to modify the template of plant degradation enzyme. Finally, using the Taguchi experimental design-assisted molecular dynamics simulation method, the suitable external environmental conditions of plant-microbe combined remediation of the PCB-contaminated soil were determined. In total, six multifunctional plant degradation enzymes were designed, which exhibited a significantly improved efficiency of PCB degradation. In comparison to the complex of plant absorption enzyme, plant degradation enzyme, and microorganism mineralization enzyme (6QIM-3GZX-1B85), the six multifunctional plant degradation enzymes exhibited significantly higher efficiency (2.10-2.38 times) in degrading the PCBs, with a maximum of 2.69 times under suitable external environmental conditions.

Distribution and Carcinogenicity of PCBs in Soil Contaminated with Transformer Oil in Selected Locations in Jos, Plateau State Nigeria

Soil from the vicinity of transformers installation in different locations in Jos, Plateau State was investigated for Polychlorinated Biphenyls (PCBs). The assessment was carried out for both total PCBs and congeners using Agilent 6975 GC-MS in ten different locations. The soil samples were extracted with 1:1 hexane- acetone in an ultrasonic bath, concentrated and cleaned with column chromatography using silica gel and hexane as eluting solvent. The result shows five locations were polluted with PCBs that exceed the maximum limit of 2.0mg/kg as permitted by the United States Toxic Substance Control Act (TSCA) with the following values NGS 1 (14.25), NGS 3 (4.47), NGS 6 (9.48), NGS 9 (8.21) and NGS 10 (5.05) while the others have NGS 2 (0.64), NGS 4 (1.85), NGS 5 (0.83), NGS 7 (0.95) in mg/kg respectively, NGS 8 value was below the instrument detection limit (0.0012mg/kg). The order for the total PCBs concentration in these selected locations are NGS 1 &gt; NGS 6 &gt; NGS 9 &gt; NGS 10 &gt; NGS 3 &gt; NGS 4 &gt; NGS 7 &gt; NGS 5 &gt; NGS 2. The carcinogenicity of the dioxin-like PCBs calculated as total toxicity equivalence concentration (TTEC) in these selected locations corresponds to NGS 1 (0.00001), NGS 2 (0.0000051), NGS 3 (0.0000054), NGS 4 (0.0000051), NGS 6 (0.0000063), NGS 7 (0.0000078), NGS 9 (0.0000051) and NGS 10 (0.0000051) respectively. The total cancer risk computed by addition of cancer risk due to ingestion, inhalation and dermal contact revealed that all the locations have very low to low cancer risk compared with the value recommended by the United State.

Arbuscular mycorrhizal fungus facilitates ryegrass (Lolium perenne L.) growth and polychlorinated biphenyls degradation in a soil applied with nanoscale zero-valent iron

Nanoscale zero-valent iron (nZVI) shows an excellent degradation effect on chlorinated contaminants in soil, but poses a threat to plants in combination with phytoremediation. Arbuscular mycorrhizal (AM) fungus can reduce the phyototoxicity of nZVI, but their combined impacts on polychlorinated biphenyls (PCBs) degradation and plant growth remain unclear. Here, a greenhouse pot experiment was conducted to investigate the influences of nZVI and/or Funneliformis caledonium on soil PCB degradation and ryegrass (Lolium perenne L.) antioxidative responses. The amendment of nZVI significantly reduced not only the total and homolog concentrations of PCBs in the soil, but also the ryegrass biomass as well as soil available P and root P concentrations. Moreover, nZVI significantly decreased leaf superoxide disutase (SOD) activity, while tended to decrease the protein content. In contrast, the additional inoculation of F. caledonium significantly increased leaf SOD activity and protein content, while tended to increase the catalase activity and tended to decrease the malondialdehyde content. The additional inoculation of F. caledonium also significantly increased soil alkaline phosphatase activity, and tended to increase root P concentration, but had no significantly effects on soil available P concentration, the biomass and P acquisition of ryegrass, which could be attributed to the fixation of soil available nutrients by nZVI. Additionally, F. caledonium facilitated PCB degradation in the nZVI-applied soil. Thus, AM fungus can alleviate the nZVI-induced phytotoxicity, showing great application potentials in accompany with nZVI for soil remediation.

Legacy persistent organochlorine pollutants and polycyclic aromatic hydrocarbons in the surface soil from the industrial corridor of South India: occurrence, sources and risk assessment.

Conversion of agricultural fields into the industrial corridor under the State Industries Promotion Corporation of Tamil Nadu Limited (SIPCOT) necessitated the investigation of soil-borne organic contaminants. This study is the first attempt to evaluate the occurrence of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in soils from Mambakkam and Cheyyar SIPCOT belt, along the residential, industrial and agricultural transects. Concentrations of Σ28PCBs, Σ16PAHs and OCPs were in the range 0.3-9ng/g, 33-2934ng/g and nd-81.4ng/g, respectively. Residential areas showed higher OCP concentrations than other site types, probably due to their frequent use in vector control programmes. DDT isomers and α-isomer of endosulfan showed low concentrations indicating past usage of these OCPs. Principal component analysis indicated that high-temperature combustion and industrial processes might be the major sources of high molecular weight PAHs, while low-temperature combustion processes might be responsible for low molecular weight PAHs. PCBs in soil were probably attributed to unaccounted combustion processes of e-waste in the region. Carcinogenic PAHs and Σ28PCBs were higher in the industrial sites. Mean Σ28PCBs at Mambakkam (4.8ng/g) was significantly higher (p < 0.05) than that at the incipient industrial corridor Cheyyar (2.7ng/g). Lower chlorinated PCBs (3-Cl and 4-Cl) amounted to more than half of Σ28PCBs in 75% of the sites. Total toxic equivalents (TEQs) of PAHs (total BaPeq) were found to be maximum in industrial areas. Maximum contribution to TEQs due to dioxin-like-PCBs was from PCB-157, followed by PCB-189.

Potential use of Impatiens balsamina L. for bioremediation of lead and polychlorinated biphenyl contaminated soils

AbstractIn recent years, due to the improper dismantling of electronic waste (e‐waste) in China, high levels of lead (Pb) and polychlorinated biphenyls (PCBs) have been released into the environment, which posed potential health risks to residents, especially to children. A pot‐culture experiment was carried out to evaluate the phytoremediation potential of PCBs and Pb co‐contaminated soil by the use of Impatiens balsamina L. The results indicated that PCBs and Pb had negative effect on plant growth, while the presence of PCBs partially alleviated Pb toxicity to I. balsamina. The existence of PCBs showed nonsignificant effects on Pb uptake by I. balsamina. However, the presence of PCBs influenced the distribution of Pb among plant tissues. The order of Pb accumulation in tissues was roots &gt; stems &gt; leaves, indicating the plant may be suitable for the phytostabilization of Pb in soil. The degradation rates of PCB 18 (25–68%) and PCB 28 (14–61%) in the planted soil was significantly higher than that in the unplanted soil, which confirmed the vegetation is beneficial for the biodegradation of PCBs in soils. Plant–microbial consortia in the rhizosphere make a predominant contribution to PCBs dissipation in the co‐contaminated soil. Significant differences in microbial taxonomic composition between the contaminated soils and a blank control were observed. I. balsamina could have the potential for remediating PCBs and lead co‐contaminated soils, even though further field studies are still required.