PAHs In Soil Research Articles

Study on Characteristics of Decomposition and Fluorescence Emission of PAHs in Soil by Pulsed Ultraviolet Laser

Study on Characteristics of Decomposition and Fluorescence Emission of PAHs in Soil by Pulsed Ultraviolet Laser

Background levels of OCPs, PCBs, and PAHs in soils from the eastern Pamirs, China, an alpine region influenced by westerly atmospheric transport

Long-range atmospheric transport (LRAT) plays a crucial role in the occurrence of persistent organic pollutants (POPs) in remote regions. When studying the LRAT of POPs on the Tibetan Plateau, westerly-controlled regions have received insufficient attention compared with regions influenced by the Indian monsoon or air flow from East Asia. We investigated the residual levels of POPs in soils from the eastern Pamirs and used air backward trajectory analysis to elucidate the influence of potential source regions via LRAT. Organochlorine pesticides (OCPs, mainly comprising DDTs, HCHs, and HCB), polychlorinated biphenyls (PCBs, mainly comprising penta- and hexa-CBs), and polycyclic aromatic hydrocarbons (PAHs, mainly comprising three- and four-ring) were detected at low concentrations of 40–1000, <MDL–88, and 2100–34,000 pg/g, respectively. We elucidated three major geographical distribution patterns of POPs, which were influenced by (1) the distribution of total organic carbon and black carbon in soil, (2) historical use of pesticides in the Tarim Basin, and (3) continuous emissions. Central Asia and the Tarim Basin were major potential source regions of POPs reaching the eastern Pamirs via LRAT. Historical use of technical HCH or lindane and technical DDT in potential source regions may contribute to the accumulation of HCHs and DDTs in the eastern Pamirs, respectively. Local sources seem to play a more important role in the occurrence of PAHs in the study area. By being under the control of less contaminated westerly air flow, the eastern Pamirs are more pristine than the core of the Tibetan Plateau where the Indian and East Asia monsoons deliver contaminants from highly industrialized areas in East China and India.

Correction method of effect of soil moisture on the fluorescence intensity of polycyclic aromatic hydrocarbons based on near-infrared diffuse reflection spectroscopy.

Soil moisture has a strong impact on the fluorescence intensity of PAHs, which is undoubtedly posing a challenge for the development of rapid real-time fluorescence detection technology of PAHs in soil. In this work, NIR diffuse reflectance spectroscopy was used to correct the fluorescence spectra of PAHs in order to reduce the effect of the soil moisture. To establish the correction method, eight soil samples with different moisture contents and a given phenanthrene concentration (8mg/g) were prepared. The fluorescence and NIR diffuse reflectance spectra were collected for of all samples. It was found that the fluorescence spectra of the soil samples that vary with the moisture content together with the NIR diffuse reflectance spectra were considered for the correction of the fluorescence intensity of phenanthrene related to the moisture content. The results showed that the ratio of the fluorescence intensity at 384nm to the NIR diffuse reflectance spectrum absorbance at 5184cm-1 can be used as a correction factor to reduce the effect of the soil moisture on the fluorescence intensity of phenanthrene in the soil. The validity of the correction method was verified by the quantitative analysis of PAHs with different concentrations and soil moisture contents. The results showed better linearity between the fluorescence intensity and the concentration of PAHs after the correction (with a correlation coefficient R of 0.99) than before the correction (with R of 0.86). The relative prediction errors for three unknown samples decreased from 19%, 51% and 40% before the correction to 5%, 13% and 0.44% after the correction, respectively, indicating the feasibility of the detection of PAHs in the soil by the combination of fluorescence and NIR diffuse reflectance spectroscopy.

Polycyclic aromatic hydrocarbons in urban and rural residential soils, levels, composition profiles, source identification and health risk &amp; hazard

The presence of PAHs in soil and the close proximity of soils to humans may lead to human exposure through various pathways. Therefore, levels of priority sixteen PAHs in soils were measured for human and environmental health risk assessments. No recent study on human and environmental health effects due to PAHs in soils is available for Delhi. The levels of total PAHs in soils ranged between 213–851 μg kg−1 with the mean of 550 ± 55 μg kg−1, which was comparatively lower in rural area. Seven carcinogenic PAHs (7CPAHs) accounted for 28.6% of ∑16PAHs. However, benzo(a)pyrene toxicity equivalency (BaPTE) of 7CPAHs accounted for 98.2% to ∑BaPTE. Lifetime average daily dose (LADD) of PAHs through soil for human adults and children was 9.43 × 10−8 mg kg−1 d−1 and 3.53 × 10−7 mg kg−1 d−1, respectively. The estimated incremental lifetime cancer risk (ILCR) for children (4.80 × 10−5) was comparatively higher than adults (1.29 × 10−5). The index of additive cancer risk (IACR), potential threat to potable groundwater water quality from leaching of carcinogenic PAHs from soil were also estimated and presented. The observed levels of PAHs in soils and their human health risk and environmental health hazard at different locations were assessed using recommended guidelines.

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.

Fungal Community, Metabolic Diversity, and Glomalin-Related Soil Proteins (GRSP) Content in Soil Contaminated With Crude Oil After Long-Term Natural Bioremediation.

Fungi have increased tolerance to environmental stress (also related to the access of pollutants, e.g., trace elements and polycyclic aromatic hydrocarbons PAHs). The aim of the study was to evaluate the mycobiome and functional diversity of fungi in long-term crude-oil contaminated soils as the potential bioremediators of oil contaminated sites. Samples were taken from three historical oil wells (over a century old) at two distances: within a 0.5 m radius of the oil wells (OWP1, OWP2, and OWP3) and within a 3 m radius from the oil wells as the controls (OW1, OW2, and OW3). Next generation sequencing (for the ITS region) was accompanied with determination of the functional fungal community based on Biolog FFPlates, glomalin related soil protein (GRSP) content, trace element and PAHs concentration. The research hypothesis assumed that long-term natural bioremediation of crude oil contaminated soils can contribute to intensive development of a unique fungal community adapted to the contamination conditions. The identification of such fungi can be of particular importance in soil bioremediation. There were significant differences in the fungal community and functional diversity between the soil samples. The soils collected directly from the oil wells were characterized by higher biological activity and higher diversity of PAH-degrading fungal candidates compared to the soils collected within 3 m of the oil wells. The total glomalin-related soil proteins (T-GRSP) and easily-extractable glomalin-related soil proteins (EE-GRSP) contents were lower in soil samples taken directly from the crude oil well. The control soil (OW) subjected to a long-term natural remediation may already have sufficient conditions for the growth and development of mycorrhizal fungi. The mycobiome of the soils collected directly from the oil wells (OWP1, OWP2, and OWP3) was characterized by a 35% share of PAH-degrading candidates, compared to the soil collected at the 3 m distance from the oil wells (OW1, OW2, and OW3) at < 5%. The main PAH-degrading fungal candidates belong to genera Ilyonectria, Chaetomium, Gibberella, Paraphoma, Schizothecium, Pseudorobillarda, Tetracladium, Ganoderma, Cadophora, Exophiala, Knufia, Mycoleptodiscus, Cyphellophora, Fusicolla, Devriesia, Didymella, Plenodomus, Pyrenochaetopsis, Symbiotaphrina, Phallus, Coprinellus, Plectosphaerella, Septoriella, and Hypholoma. The share of three- and four-ringed PAHs in soil was higher as the distance from the oil well increased. These results may indicate that more effective degradation processes occur closer to the oil wells.

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.

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...

Development of laboratory-scale sequential electrokinetic and biological treatment of chronically hydrocarbon-impacted soils

This study focused on the remediation of a chronically diesel-polluted soil by combining an electrokinetic treatment with a variety of bioremediation approaches. Priority within the sequential treatment was given to electrokinetic remediation (EKR) since the application of natural attenuation (NA), biostimulation and site-specific bio-augmentation resulted in very low degradation performance for total petroleum hydrocarbons (TPH) and polycyclic hydrocarbons (PAH). The application of 20-day EKR (1.0 V cm−1 with polarity reversal) led to 47.2 % and 46.2 % removal of TPH and PAH, respectively, and exerted a negative impact on bacterial abundance, as determined indirectly by quantitative PCR of 16S rRNA genes and community function, as investigated by community-level physiological profiling. These adverse effects were transient and, after a 50-day NA treatment applied downstream from EKR, bacterial abundance was an order of magnitude higher than that found in the initial soil and TPH and PAH removals were significantly higher than those attained by EKR (64.1 % and 56.3 %, respectively). The combination of EKR with site-specific bioaugmentation led to the greatest TPH and PAH degradation (76.0 % and 78.6 %, respectively). The results indicate that bioremediation can be successfully applied downstream from EKR and that the adverse effects exerted by this physico-chemical approach on soil microbiota are reversible.

Occurrence, sources and ecological and human health risks of polycyclic aromatic hydrocarbons in soils from some functional areas of the Nigerian megacity, Lagos.

The study investigated the levels of the USEPA 16 PAHs in soils collected from selected functional areas (cemetery, commercial, industrial and residential areas) of the Nigerian megacity, Lagos. The soil samples were subjected to ultrasonic-assisted extraction in a 1:1 (v/v) mixture of dichloromethane/hexane, and the PAHs in the resulting extracts were determined by gas chromatography-mass spectrometry. The Σ16 PAHs in soils of these functional areas varied between 890-4675, 485-4513, 111-15,577 and 509-2047μgkg-1 for cemetery, industrial, commercial and residential areas, respectively. The benzo(a)pyrene carcinogenic (BaPTEQ) and mutagenic equivalency (BaPMEQ) values of PAHs in these soils spanned from 523 to 1046 and 446 to 1129 µgkg-1, respectively. The hazard index values suggested that there are adverse (non-carcinogenic) health effects for a child's exposure to PAHs in soils of commercial areas. The cancer risk values resulting from an adult's and a child's exposure to PAHs in these urban soils via dermal contact and oral ingestion surpassed the target value of 10-6 which suggested that there is a considerable cancer risk relating to human exposure to PAHs in these urban soils. An ecological risk assessment making use of soil quality guidelines and risk quotients suggested a low ecological risk to organisms in soils of these functional areas except for those from commercial areas. PAH isomeric ratios and principal component analysis indicated that PAHs in these soils arise from petrogenic inputs, such as occasional spills of liquid petroleum fuels and discharges from automobile workshops and generator houses, as well as pyrogenic processes including traffic emissions and combustion of fossil fuels and biomass.

Soil PAHs against varied land use of a small city (Tezpur) of middle Brahmaputra Valley: seasonality, sources, and long-range transport.

This study reports soil PAHs from a small city (Tezpur) of the mid-Brahmaputra Valley. The soil PAHs has been assessed from representative land use using detailed protocol of extracting, cleaning, and quantitative analysis by HPLC technique. The concentrations of PAHs showed minimum spatial variability and yet showed strong seasonal variability, which could be typical of small cities having weak local source strengths. On examining the air mass reaching the region, it appeared that there has been explicit effect of long-range transport. The HYSPLIT back trajectories reaching the study area during different seasons showed variations in terms of their origins and transport pathways. This might have led to differential long-range transport of PAHs, which is reflected in the seasonal variabilities of the concentrations of PAHs. The seasonal variations were much profound with the highest ΣPAHs concentration during post-monsoon (7961ngg-1) followed by pre-monsoon (2414ngg-1) and monsoon (773ngg-1) season. The toxicity of the PAHs was examined as BaP equivalent (BaPeq) concentrations, which were found to be on the lower side as compared to the studies conducted elsewhere. The percentage contribution of 3- and 4-ring compounds was found to be greater. An attempt also was made to apportion the sources of the PAHs by application of diagnostic ratios, principal component analysis-multiple linear regression (PCA-MLR) and hierarchal cluster analysis (HCA), which revealed that coal and biomass burning and vehicular emissions are the major contributors to the PAHs load in Tezpur city.

Viability and distribution of bacteria immobilized on Sawdust@silica: The removal mechanism of phenanthrene in soil.

Immobilized cells (ICs) have been widely used to enhance the remediation of organic-contaminated soil (e.g., polycyclic aromatic hydrocarbons, PAHs). Once ICs are added to the heterogeneous soil, degradation hotspots are immediately formed near the carrier, leaving the remaining soil lack of degrading bacteria. Therefore, it remains unclear how ICs efficiently utilize PAHs in soil. In this study, the viability of Silica-IC (Cells@Sawdust@Silica) and the distribution of inoculated ICs and phenanthrene (Phe) in a slurry system (soil to water ratio 1:2) were investigated to explore the removal mechanism of PAHs by the ICs. Results showed that the Silica-IC maintained (i) good reproductive ability (displayed by the growth curve in soil and water phase), (ii) excellent stability, which was identified by the ratio of colony forming units in the soil phase to the water phase, the difference between the colony number and the DNA copies, and characteristics of the biomaterial observed by the FESEM, and (iii) high metabolic activity (the removal percentages of Phe in soil by the ICs were more than 95% after 48h). Finally, the possible pathways for the ICs to efficiently utilize Phe in soil are proposed based on the distribution and correlation of Phe and ICs between the soil and water phase. The adsorption-degradation process was dominant, i.e., the enhanced degradation occurred between the ICs and carrier-adsorbed Phe. This study provided new insights on developing a bio-material for efficient bio-remediation of PAHs-contaminated soil.

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.

Source Apportionment of Soil PAH Concentration and Associated Carcinogenic and Mutagenic Potencies by Combined Utilization of PMF and Toxic Assessment: A Case Study in North China

ABSTRACT The knowledge of PAH sources in soil plays an important role in making the decision of pollution emission restriction, as well as toxic information. The present study developed a modified receptor model to apportion the contribution of various sources to PAHs and associated toxic. PMF model was selected as the basic source apportionment model to identify sources and apportion their contributions. Toxic assessment models, including carcinogenicity assessment model and mutagenicity assessment model, were then used with PMF to obtain toxic-oriented source contribution. To attain this objective, 16 priority PAHs in the soil around Miyun Reservoir were selected as a case study. The results showed that the dominant source of soil PAHs was wood/biomass combustion (31.02%), followed by vehicular source (27.17%), petroleum source (21.27%) and coal combustion (20.53%). While the highest contributor to carcinogenicity and mutagenicity was a vehicular source, with a proportion of 36.61% and 41.46%, respectively. This study highlights the combined utilization of the source apportionment model and toxic assessment model. The approach was valuable for providing comprehensive source-oriented risk information, and expanding the application of both PMF and toxic assessment.

The convertion of sewage sludge to biochar as a sustainable tool of PAHs exposure reduction during agricultural utilization of sewage sludges

There is a discussion in the literature whether PAHs introduced with biochar are safe and whether they are persistent in the environment. The persistence of PAHs (Ctot – total and Cfree – freely dissolved) in sewage sludge (SSL) or SSL-derived biochar-amended soils was investigated. Biochar were produced at 500, 600 and 700 °C. We also compared the persistence of PAHs in these experimental treatments depending on the plants cultivated (grass, clover and thale cress). We showed that the Ctot PAHs in the biochar-amended soils exhibited higher persistence than in the SSL-amended soil. The opposite trend was observed for Cfree PAHs. A higher reduction of Cfree PAHs was noted in the biochar-amended soils than in SSL-amended soil. The persistence of both Cfree and Ctot PAHs clearly varied between the biochars produced at different temperatures. It should be stated that despite that for biochar the persistence of Ctot PAHs is higher compared to SSL-amended soils, an opposite trend is observed for the fraction of Cfree (which is directly responsible for the toxic effect), and this entails a lower risk to the environment (lower mobility and bioavailability). The plants had a significant impact on Ctot PAHs content depending on the number of PAH rings.

Source identification of polycyclic aromatic hydrocarbons in terrestrial soils in Chile

In this study, a combination of the diagnostic binary ratios of PAHs and multivariate descriptive statistics was applied to identify the sources of PAHs in Chilean terrestrial soils. A total of 15 PAHs from the terrestrial soil of 28 locations in three cities of Chile were chemically characterized using gas chromatography mass spectrometry (GC-MS). The total concentrations of twelve likely carcinogenic PAHs were defined as the sum of Phe, An, Fluo, Pyr, B[a]A, Chry, B[b]F, B[k]F, B[a]P, Ind, D[a, h]A and B[g, h, i]P and ranged from 0.0215 to 4.37 μg g−1 with an arithmetic mean of 0.618 ± 0.911 μg g−1. The levels of these PAHs were classified as moderate to high compared to World Soils (WS). All sampling stations were dominated by high molecular weight PAHs, four-ring (39.1%) and five-ring (29.6%) PAHs were the most abundant groups in the terrestrial soils of Chile. The PAH diagnostic ratios suggested that PAHs are primarily of pyrogenic origin. Further multivariate descriptive statistics (i.e., hierarchical cluster analysis (HCA) and principal components analysis (PCA)) identified pyrogenic combustion as the main emission source of PAH contamination in Chilean terrestrial soils.

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.

非平滑非负矩阵分解解析土壤多环芳烃三维荧光光谱

非平滑非负矩阵分解解析土壤多环芳烃三维荧光光谱

Raman-infrared spectral fusion combined with partial least squares (PLS) for quantitative analysis of polycyclic aromatic hydrocarbons in soil

Spectroscopy is an effective method for the rapid detection of PAHs in soil, but the predictive performance is not satisfactory due to interference from other substances.

Study on quantitative methods of laser-induced two-dimensional fluorescence spectroscopy of multicomponent PAHs in soils

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed