PCBs In Soil Research Articles

The Detection and Remediation Technologies of PCB-Contaminated Soils

Polychlorinated biphenyls (PCBs) are the organic pollutants that of persistence, fat soluble and character such as biological toxicity, widely distributed. It also showed a highly persistent in the environment, strong enrichment and high biological toxicity, having the serious harm to human health and ecological environment. The final destination of PCBs in the environmental system is soil and sediment due to its highly distribution coefficient between sediment and water. PCBs in soil is difficult to decompose and has strong adsorption. Therefore, the detection and remediation of PCBs in soil is very critical. PCBSin soil detection technologies becoming matured at present. Such as dual column gas chromatography analysis method, GC – MS, enzyme immunoassay for PCBs detecting have been widely used. Low cost, high resolution and high accuracy detection technology has been more and more attention. For the remediation technologies of contaminated soils, chemical remediation, bioremediation technologies developed fast. Efficient, economic and environmental multiple remediation method, such as elution pretreatment on contaminated soil, combination of multiple remediation techniques are the development direction of the future. Based on the analysis on detection and remediation technologies of PCBs in soil. The principle and suitable condition of different detection methods and remediation technologies of PCBs in soil was studied in this paper. To provide technical support to remediation the PCB-contaminated soils.

Pcbs in Soils around an Old Electric Transformer Factory in North China

The 28 surface soil samples (0-10 cm) were collected from the urban area of Baoding city nearby an old electric transformer factory for analysis of 84 PCB congeners. Total PCBs concentrations ranged from 0.69 to 11.15 ng/g (mean: 3.62 ng/g). The PCBs concentration (5.72 ng/g) for sampling sites in the vicinity (0-2.5 km) of the transformer factory was higher than that (2.96 ng/g) for other sampling sites. Compositional patterns of individual congener and homologs were similar to those of Chinese transformer oils. The top five congeners were PCB-6, 18, 22, 33 and 31/28 among the identified PCBs. Low chlorinated PCBs (di-to tetra-CBs) accounted for 69.58% of total PCBs concentrations and the predominant PCB homologs were tri-CBs (46.38%), penta-CBs (13.73%) and di-CBs (9.47%), respectively. Principal component analysis showed that technical formulations such as Chinese transformer oil, Aroclor1242, 1016, KC-300 and A-30 were the main sources of soils PCBs from Baoding city. The TEQ concentrations based on ten dioxin-like PCBs ranged from 0 to 26.0986 ng/kg with the mean value as 7.3336 ng/kg.

Long-range atmospheric transport of persistent organic pollutants to remote lacustrine environments

Concentrations, temporal trends and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs) were determined in soil and 210Pb-dated sediment cores from remote lacustrine environments (El Tule and Santa Elena lakes) in rural areas of Central Mexico. In both areas, the concentrations of target analytes in soil and sediment samples were comparable and indicative of slightly contaminated environments. The prevalence of low-molecular-weight PAHs in soils suggested their mainly atmospheric origin, in contrast to the aquatic sediments where runoff contribution was also significant. Increasing contamination trends of PCBs and PBDEs were evident, showing maximum fluxes of 4.8±2.1 and 0.3±0.1ngcm−2a−1 for PCBs and PBDEs, respectively. The predominance of lower-brominated PBDEs and lower-chlorinated PCBs in soils and sediments indicated that their presence is mostly due to long-range atmospheric transport.

Effect of Carrier Gas Flow Rate in Thermal Desorption Process of PCBs Contaminated Soil

A real PCBs contaminated soil was heated at 500°C using pure nitrogen as carrier gas under different flow rate to investigate the influence of carrier gas flow rate on the thermal desorption process. After 1 hour thermal treatment, the residual PCBs in soil decreased and the removal efficiency (RE) of PCBs is up to 95.1%. The distributions of PCBs in soil under different flow rate were identical. The World Health Organization toxic equivalency quantity (WHO TEQ) of PCBs in soil got its lowest value at 400Nml/min. Tetra-and higher chlorinated PCBs desorbed to carrier gas increased with increased flow rate, while the total amount of PCBs, Tri-and lower chlorinated PCBs first increased then decreased. The distributions of PCBs in carrier gas became more closely to the raw soil with increased flow rate. The TEQ of PCBs in carrier gas increased with increased flow rate. Increased flow rate enhanced the mass transfer of PCBs in the soil but shortened the preheating time of carrier gas and the retention time of carries gas, weakening the mass transfer and degradation process in gas phase. The RE of WHO TEQ of PCDDs in treated soil decreased from 86.7% to 83.2% with increased flow rate while the RE of WHO TEQ of PCDFs decreased from 85.4% to 70.0%. After thermal treatment process, the total amount of PCDD/Fs TEQ in soil and carrier gas increase from 43.8% to 18.6% times of that in raw soil. Considering removal efficiency of PCBs and PCDD/Fs and generation of PCDD/Fs in soil and gas phase, an optimized flow rate should be set at about 400Nml/min.

Occurrence of PCDD/PCDFs and PCBs in soil and comparison with CYP1A response in PLHC-1 cell line

The responsiveness of CYP1A (gene transcription and EROD enzyme activity) in the cell line Poeciliopsis lucida hepatoma (PLHC-1) upon exposure to extracts of contaminated soil samples was investigated and compared to levels of PCDD/PCDFs and PCBs including non-ortho obtained by GC/MS analysis. Soil samples A and B were collected in sites A and B. Two fractions, not purified (np) and purified (p), were obtained from each sample and analyzed for PCDD/PCDF and PCB content by GC/MS; in parallel they were tested for 24h with PLHC-1. CYP1A response was investigated at gene (RT-qPCR) level and as 7-ethoxyresorufin-O-deethylase (EROD) enzyme activity. Chem-TEQs and Bio-TEQs were then calculated. ∑TEQ calculated for PCDD/Fs and PCBs was 0.081pg/g and 20.32pg/g for samples A and B, respectively. PLHC-1 showed less up-regulation of cyp1a gene on exposure to the two purified fractions (Ap 2.1-fold and Bp 1.8-fold) than to non-purified fractions (up to 15-fold for Anp and 13-fold for Bnp). EROD was also induced 2.38- and 9.44-fold in the two purified fractions (Ap and Bp) compared to model inducer 2,3,7,8-TCDD, and up to 16.03-fold for non-purified Anp and 33.79-fold for Bnp. The combination of CYP1A response, obtained in a PLHC-1 cell-based bioassay, with contaminant residue analysis provided a better description of the presence and toxicity of dioxin-like compounds in an environmental matrix.

Highly spatially- and seasonally-resolved predictive contamination maps for persistent organic pollutants: Development and validation

A reliable spatial assessment of the POPs contamination in soils is essential for burden studies and flux evaluations. Soil characteristics and properties vary enormously even within small spatial scale and over time; therefore soil capacity of accumulating POPs varies greatly. In order to include this very high spatial and temporal variability, models can be used for assessing soil accumulation capacity in a specific time and space and, from it, the spatial distribution and temporal trends of POPs concentrations. In this work, predictive contamination maps of the accumulation capacity of soils were developed at a space resolution of 1×1m with a time frame of one day, in a study area located in the central Alps. Physical algorithms for temperature and organic carbon estimation along the soil profile and across the year were fitted to estimate the horizontal, vertical and seasonal distribution of the contamination potential for PCBs in soil (Ksa maps).The resulting maps were cross-validated with an independent set of PCB contamination data, showing very good agreement (e.g. for CB-153, R2=0.80, p-value≤2.2·10−06). Slopes of the regression between predicted Ksa and experimental concentrations were used to map the soil contamination for the whole area, taking into account soil characteristics and temperature conditions. These maps offer the opportunity to evaluate burden (concentration maps) and fluxes (emission maps) with highly resolved temporal and spatial detail.In addition, in order to explain the observed low autumn PCB concentrations in soil related to the high Ksa values of this period, a dynamic model of seasonal variation of soil concentrations was developed basing on rate parameters fitted on measured concentrations. The model was able to describe, at least partially, the observed different behavior between the quite rapid discharge phase in summer and the slow recharge phase in autumn.

도심하천유역의 PCBs 농도 분포

Abstract : In this study, we have examined concentration distribution and patterns of PCBs in waters, sediments and soils in an agricultural area of South Korea to investigate the relationship between PCBs sources and concentration levels. The con-centration of PCBs in water samples were ranged from lower values below detection limit to 8.25 ug/L and the concentration of PCBs in sediment samples were ranged from lower values below detection limit to 76.67 ug/Kg. The concentration of PCBs in soil samples were ranged from lower values below detection limit to 23.51 ug/Kg. These contamination levels were far below the guideline values suggested for environmental quality assessment. The homologue patterns in samples varied from sample to sample, but isomer patterns were very similar with each other. PCB-138 and PCB-153 were predominant congeners in the soil and sediment, which were similar to the results obtained from previ-ous studies. With these results, the assessment of potential sources of PCBs contamination in the sediments of the Nakdong river basin was performed. The principal components were extracted by Principal Component Analysis(PCA). As the result of PCA, it could be expected that PCBs in samples of this study were more affected by PCB products than combustion processes and mostly affected by already-known sources. The PCBs in the soil and sediment samples were related with commercial PCB products.Key words : POPs, PCA, PCBs주제어: 잔류성 유기오염물질, 주성분 분석, 폴리염화비페닐 •Received 31 August 2012, revised 6 November 2012, accepted 12 November 2012. * Corresponding author : Tel.: 051-629-6528, E-mail: ikki@pknu.ac.kr

PCDDs, PCDFs, dioxin-like PCBs and indicator PCBs in soil from five selected areas in Slovakia

There is a lack of information regarding persistent organic pollutants (POPs) in soil from Slovakia. This paper reports the concentrations of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), 12 dioxin-like polychlorinated biphenyls (dl-PCBs) and 6 indicator PCBs associated with 32 soil samples collected in 2007 from areas in the vicinity up to several kilometres from four selected industrial PCDD/F sources in Slovakia and one background area.The results show that the total WHO1998-PCDD/F/dl-PCB-TEQ concentrations varied from 0.34 to 18.05pgg−1 dry weight (dw) and the average total TEQ concentrations in samples collected at the Šala, Košice, Krompachy and Dubová areas were 3.18, 2.64, 7.80, and 3.19pgg−1dw respectively. The average of the total WHO1998-TEQ values in three soil samples representing the background Starina area was 0.66pgg−1 dw. The predominant contaminants among 2,3,7,8-substituted PCDD/Fs, dl-PCB, and indicator PCBs was OCDD, PCB 118, and PCB 153 respectively. The major contributors to the TEQ were 2,3,4,7,8-PeCDF, PCB 126, 1,2,3,7,8-PeCDD, PCB 156 and 1,2,3,4,7,8-HxCDF+1,2,3,4,7,9-HxCDF in descending order.

Releases of Dioxin-like PCBs in Water, Soil and Residue Produced from High Thermal Processes and Waste Incinerators

This paper presents the results of DL-PCB releases to water, soil and residue from waste incinerators, crematorium and various industries such as cement, textile, paper and pulp, steel, thermal power plant, landfill sites and bricks kilns. Total TEQ as per WHO-TEFs (2006) in water, soil and residue ranged from 0.005 to 1.884pg/L, 0.007 to 33.041pg/g and 0.001 to 0.013pg/g, respectively. PCB #118 was the predominant mono-ortho congener; followed by PCB #105. PCB #77 exhibited the highest values amongst non-ortho PCBs in the samples collected.

Soil Degradation Processes from Pollution

Investigations found HCH and DDT residuals in bottom sediments from several reservoirs and lakes as well as the main rivers, Nistru and Prut (concentrations ranged between 0.2 and 15.8 ppb). The concentration of PCBs in the topsoil collected beneath the capacitors battery at the Vulcănesti substation reached a level of 7100 ppm which is exceeding the MAC by five orders of magnitude (!). With no exception, allowable concentrations of PCBs in soil were exceeded also on the territory of other investigated substations, with peaks registered at the Briceni substation (2545 ppm) and the Orhei substation (1959 ppm).

Elevated Concentrations of Pesticides and PCBs in Soils at the Southern Caspian Sea (Iran) are Related to Land Use

Soil contamination by organochlorine pesticides or PCBs is almost undocumented for Iran. Here we report a soil survey in Mazandaran and Guilan provinces that hold >30% of the agricultural areas of Iran where pesticide use is widespread. Concentration of DDTs, HCHs, cyclodienes, and PCBs were measured in 45 soil samples from different agricultural land uses and forest land. The average concentrations of ∑DDT (37 μg kg−1) and ∑HCH (21 μg kg−1) in agricultural soils are among the largest ever reported and exceed international soil screening standards. All residues were larger in agricultural than in forest soil. Within agricultural land, ∑DDT were largest for tea gardens, lindane was largest in rice fields, and cyclodiens largest in citrus orchards. The ratio of (DDD + DDE)/DDT is an index of the extent of DDT degradation in soil and was lower in tea gardens than in other soils (0.7 versus 2–5), indicating either ongoing DDT input or lower degradation rate in the tea gardens that are more acid than the other soils (pH 4.5 versus 6.5–7.0). The o,p′–DDT/p,p′–DDT ratio was about 3 in forest soils, suggesting that DDT is derived from dicofol application and not from technical DDT as in agricultural soils. The PCB 28, 180, and 138 showed the highest mean concentration compared with other PCB congeners in all land uses. This survey is the first of this kind for Iran and illustrates that concentrations of organochlorine pesticide in soil are relatively large.

Spatial Distribution of PCB Dechlorinating Bacteria and Activities in Contaminated Soil

Soil samples contaminated with Aroclor 1260 were analyzed for microbial PCB dechlorination potential, which is the rate-limiting step for complete PCB degradation. The average chlorines per biphenyl varied throughout the site suggesting that different rates ofin situdechlorination had occurred over time. Analysis of PCB transforming (aerobic and anaerobic) microbial communities and dechlorinating potential revealed spatial heterogeneity of both putative PCB transforming phylotypes and dechlorination activity. Some soil samples inhibited PCB dechlorination in active sediment from Baltimore Harbor indicating that metal or organic cocontaminants might cause the observed heterogeneity ofin situdechlorination. Bioaugmentation of soil samples contaminated with PCBs ranging from 4.6 to 265 ppm with a pure culture of the PCB dechlorinating bacteriumDehalobium chlorocoerciaDF-1 also yielded heterologous results with significant dechlorination of weathered PCBs observed in one location. The detection of indigenous PCB dehalorespiring activity combined with the detection of putative dechlorinating bacteria and biphenyl dioxygenase genes in the soil aggregates suggests that the potential exists for complete mineralization of PCBs in soils. However, in contrast to sediments, the heterologous distribution of microorganisms, PCBs, and inhibitory cocontaminants is a significant challenge for the development ofin situmicrobial treatment of PCB impacted soils.

Influence on Polychlorinated Biphenyls Content Using Three Types of Biowastes As Fertilizers In Agricultural Soils

A 4-year field study was carried out to investigate the effects of three types of biowastes application on PCB accumulation in agricultural soils. This study was based on the experiments designed for four soils in two areas of Palencia province (Spain) (Cerrato and Tierra de Campos) for non irrigated and irrigated land after applying biowaste. The amounts of the three different types of biowastes added were determined according to the fertilization needs of nitrogen for the crop. The concentrations of PCBs in soils were determined before and after biowaste application. The three biowaste treatments raise the concentration of PCBs in the soil, sewage sludge compost (SC) treatment produced the main increase in PCBs concentration, followed by municipal solid waste compost (MC) treatment and the dehydrated sewage sludge (SD) treatment. The values of biowaste treated areas were 3.7-11.5 times higher than the respective values of the non treated areas. Changes observed in the congener distribution also suggest the influence of the biowaste on the soil. The biowaste used had an average PCBs concentration of 63.16 ng g−1 with a range from 34.08 ng g−1 to 118.93 ng g−1, which are values below the EEC recommended limit (800 ng g−1). In the soils without treatment was found an average concentration 0.206 ng g−1 of PCBs, typical of areas with low levels of environmental pollution.

Highly effective degradation of polychlorinated biphenyls in soil mediated by a Ca/Rh bicatalytic system

Treatment of PCBs in soil using metallic calcium and alcohol ultimately reduced 1300 × 10 −3 mg kg −1 PCB concentration to 1.8 × 10 −3 mg kg −1. Moreover, using the metallic calcium catalyst method to promote the effective use of hydrogen gas in the presence of a specific reducing catalyst such as Rh/C, the decomposition efficiency of PCBs was notably increased despite mild reaction conditions. The total PCB concentration of treated soils decreased from 1300 × 10 −3 mg kg −1 to 0.62 × 10 −3 mg kg −1 (decomp. avg. = 99.95%). Treatment of soils with metallic calcium and a Rh/C catalyst in alcohol under mild conditions such as 0.15–0.26 MPa at room temperature is extremely effective for degradation of existing PCBs.

Uptake of PAHs into polyoxymethylene and application to oil-soot (lampblack)-impacted soil samples

Polyoxymethylene (POM) is a polymeric material used increasingly in passive sampling of hydrophobic organic contaminants such as PAHs and PCBs in soils and sediments. In this study, we examined the sorption behavior of 12 PAH compounds to POM and observed linear isotherms spanning two orders of magnitude of aqueous concentrations. Uptake kinetic studies performed in batch systems for up to 54 d with two different volume ratios of POM-to-aqueous phase were evaluated with coupled diffusion and mass transfer models to simulate the movement of PAHs during the uptake process and to assess the physicochemical properties and experimental conditions that control uptake rates. Diffusion coefficients of PAHs in POM were estimated to be well correlated with diffusants’ molecular weights as D POM ∝ ( MW ) - 3 , descending from 2.3 × 10 −10 cm 2 s −1 for naphthalene to 7.0 × 10 −11 cm 2 s −1 for pyrene. The uptake rates for PAHs with log K ow < 5.8 were controlled by the POM phase and the hydrophobicity of PAH compounds. For more hydrophobic PAH compounds, the aqueous boundary layer played an increasingly important role in determining the overall mass transfer rate. The POM partitioning technique was demonstrated to agree well with two other procedures for measuring PAH soil–water distribution coefficients in oil-soot (lampblack) containing soil samples.

Biodegradation of PAHs and PCBs in Soils and Sludges

Results from a multi-year, pilot-scale land treatment project for PAHs and PCBs biodegradation were evaluated. A mathematical model, capable of describing sorption, sequestration, and biodegradation in soil/water systems, is applied to interpret the efficacy of a sequential active–passive biotreatment process of organic chemicals on remediation sites. To account for the recalcitrance of PAHs and PCBs in soils and sludges during long-term biotreatment, this model comprises a kinetic equation for organic chemical intraparticle sequestration process. Model responses were verified by comparison to measurements of biodegradation of PAHs and PCBs in land treatment units; a favorable match was found between them. Model simulations were performed to predict on-going biodegradation behavior of PAHs and PCBs in land treatment units. Simulation results indicate that complete biostabilization will be achieved when the concentration of reversibly sorbed chemical (SRA) reduces to undetectable levels, with a certain amount of irreversibly sequestrated residual chemical (SIA) remaining within the soil particle solid phase. The residual fraction (SIA) tends to lose its original chemical and biological activity, and hence, is much less available, toxic, and mobile than the “free” compounds. Therefore, little or no PAHs and PCBs will leach from the treatment site and constitutes no threat to human health or the environment. Biotreatment of PAHs and PCBs can be terminated accordingly. Results from the pilot-scale testing data and model calculations also suggest that a significant fraction (10–30%) of high-molecular-weight PAHs and PCBs could be sequestrated and become unavailable for biodegradation. Bioavailability (large Kd, i.e., slow desorption rate) is the key factor limiting the PAHs degradation. However, both bioavailability and bioactivity (K in Monod kinetics, i.e., number of microbes, nutrients, and electron acceptor, etc.) regulate PCBs biodegradation. The sequential active–passive biotreatment can be a cost-effective approach for remediation of highly hydrophobic organic contaminants. The mathematical model proposed here would be useful in the design and operation of such organic chemical biodegradation processes on remediation sites.

Soil contamination from PCB-containing buildings.

BackgroundPolychlorinated biphenyls (PCBs) in construction materials, such as caulking used around windows and expansion joints, may constitute a source of PCB contamination in the building interiors and in surrounding soil. Several studies of soil contamination have been conducted around buildings where the caulking has been removed by grinding or scraping. The PCBs in soil may have been generated in the process of removing the caulking, but natural weathering and deterioration of the caulking may have also been a source.ObjectivesThe objectives of this study were to measure PCB levels in soil surrounding buildings where PCB-containing caulk was still in place, and to evaluate the mobility of the PCBs from caulking using the Toxicity Characteristic Leaching Procedure (U.S. Environmental Protection Agency Method 1311).DiscussionWe found soil PCB contamination ranging from 3.3 to 34 mg/kg around buildings with undisturbed caulking that contained 10,000–36,200 mg/kg PCBs. The results of the Toxicity Characteristic Leaching Procedure (leachate concentrations of 76–288 mg PCB/L) suggest that PCBs in caulking can be mobilized, apparently as complexes with dissolved organic matter that also leach off the caulking material.Conclusions and RecommendationsAlthough these new findings are based on a small sample size, they demonstrate the need for a national survey of PCBs in building materials and in soil surrounding these buildings. Because the buildings constructed during the time the PCB caulking was in use (1960s and 1970s) include schools, hospitals, and apartment buildings, the potential for exposure of children is a particular concern. It is necessary to reconsider the practice of disposing of old PCB caulking removed during building renovations in conventional landfills, given the apparent mobility of PCBs from the caulking material. Disposal of some caulking material in nonhazardous landfills might lead to high PCB levels in landfill leachate.

Levels and vertical distribution of PCBs in agricultural and natural soils from Sweden

Soils represent an important reservoir for persistent organic pollutants (POPs) in the terrestrial environment and thus the fate of contaminants deposited to the surface soils is important to understand. Since only a limited number of studies of the vertical distribution of POPs are available in the literature, the purpose of this study was to collect and analyze PCB concentrations in different layers of soil cores taken at agricultural and non-agricultural sites in Sweden. PCB concentrations at the agricultural site were nearly uniform on a dry weight basis throughout the depth considered (0-12 cm) while a distinct gradient with depth was observed at the five non-agricultural sites. On an organic carbon normalized basis, the concentration gradient was maintained at three of the non-agricultural sites while a more uniform distribution was observed at the other two sites. A statistically significant relationship between dry weight soil concentrations and organic carbon content was determined for all PCB congeners in the surface layers (0-1 cm) but not in the deeper layers (4-5 cm, 9-10 cm). These results were interpreted in relation to vertical soil transport processes and then the implications for environmental fate models including soil compartments were discussed.

Analysis of PCBs in soils and sediments by microwave-assisted extraction, headspace-SPME and high resolution gas chromatography with ion-trap tandem mass spectrometry

A procedure for the determination of seven indicator PCBs in soils and sediments using microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) prior to GC-MS/MS is described. Optimization of the HS-SPME was carried out for the most important parameters such as extraction time, sample volume and temperature. The adopted methodology has reduced consumption of organic solvents and analysis runtime. Under the optimized conditions, the method detection limit ranged from 0.6 to 1 ng/g when 5 g of sample was extracted, the precision on real samples ranged from 4 to 21% and the recovery from 69 to 104%. The proposed method, which included the analysis of a certified reference material in its validation procedure, can be extended to several other PCBs and used in the monitoring of soil or sediments for the presence of PCBs.

Comprehensive comparison of classic Soxhlet extraction with Soxtec extraction, ultrasonication extraction, supercritical fluid extraction, microwave assisted extraction and accelerated solvent extraction for the determination of polychlorinated biphenyls in soil

This paper compares the extraction effectiveness of six different commonly applied extraction techniques for the determination of PCBs in soil. The techniques included are Soxhlet, Soxtec, ultrasonication extraction, supercritical fluid extraction, microwave-assisted extraction and accelerated solvent extraction. For none of the techniques were the extraction conditions optimized, but instead the extraction parameters were based on the experience from previous successful investigation published by a number of research groups worldwide. In general, all extraction techniques were capable of producing accurate data for one native PCB contaminated soil diluted with another soil sample to obtain two concentration levels. It could therefore be concluded that any of the investigated techniques can be used with success if the extraction conditions applied are chosen wisely.