Distributions and concentrations of PAHs in Hong Kong soils

Distribution of heavy metal pollution in sediments from an acid leaching site of e-waste

The spatial distribution, bioavailability, potential risks and emission sources of 12 heavy metals in sediments from an acid leaching site of e-waste were investigated. The results showed that the sediments from the acid leaching site were significantly contaminated with Cu, Zn, Cd, Sn, Sb and Pb, especially in the middle sediments (30-50 cm), with average concentrations of 4820, 1260, 10.7, 2660, 5690 and 2570 mg/kg, respectively. Cu, Cd and Pb were mainly present in the non-residual fractions, suggesting that the sediments from the acid leaching site may exert considerable risks. Mn, Ni, Zn, Sn and Sb were predominantly associated with the residual fraction. Despite their low reactivity and bioavailability, uncommon pollutants, such as Sn and Sb, may exert environmental risks due to their extremely elevated total concentrations. All of these results indicate that there is an urgent need to control the sources of heavy metal emission and to remediate contaminated sediments.

CAPTURE ABSTRACT

In addition to Ni, Cu, Zn, Cd and Pb, the sediments from an acid leaching site in Guiyu were heavily polluted with uncommon heavy metal pollutants, such as Sn and Sb.

Quantification of PAHs and health risk via ingestion of vegetable in Khyber Pakhtunkhwa Province, Pakistan

This study was conducted to evaluate the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the soil and vegetable irrigated with wastewater in 11 districts of Khyber Pakhtunkhwa (KPK) Province (Pakistan). The ∑16PAH ranged from 223 to 929 μg/kg in the soils with highest concentration in the soil of high urbanized district (Peshawar), while the lowest concentration in the soil of less urbanized district (Lakki Marwat). PAH concentrations in vegetable ranged from 51.6 to 402 μg/kg on dry weight bases (d.w). Naphthaene, phenanthrene, fluoranthene and pyrene were frequently observed in vegetable. The concentrations of higher molecular weight PAHs were lower in vegetable as compared to low molecular weight PAHs. The highest PAH concentrations were observed in leafy vegetable (lettuce>spinach). The highest TEQ value (7.2) was observed for pyrene following by naphthalene (4.9) for the samples collected from Mardan, while the lowest mean TEQ value (0.12) was found for acenaphthylene followed by benzo[k]fluoranthene (0.26) in Peshawar. The highest TEQ value was 4.1 for flouranthene followed by 3.8 for naphthalene in the KPK province. The uniqueness of this study is the quantification of PAHs in the soil and vegetable collected from a large area of KPK Province which are rapidly urbanizing.

Distribution and source apportionment of polycyclic aromatic hydrocarbons in soils and leaves from high-altitude mountains in southwestern china

Several studies have investigated the distribution patterns and geographic sources of polycyclic aromatic hydrocarbons (PAHs) in mountainous areas. Little is known about how different sources contribute to PAH concentrations at different elevations along mountain slopes. To estimate the distribution and sources of PAHs at different altitudes in mountainous areas of southwestern China, samples of soils and leaves from trees were collected from 1000 to 1500 m asl in the Dawangling forest and analyzed for PAHs. Total PAH concentrations ranged from 93.9 to 802.3 ng g (average, 252.3 ng g) in soils and from 4.1 to 100.9 ng g (average, 23.1 ng g) in leaves. Our results suggest that soil PAH levels in the study area could be classified as "weakly contaminated." The PAH levels in leaves from the Dawangling forest were lower than those found in Himalayan spruce needles from the central Himalayas in China and from an agricultural station in southern England. Total PAHs in the Dawangling forest soils increased with elevation, primarily due to the low-molecular-weight PAHs, which accumulated in samples from higher altitudes. In contrast, high-molecular-weight PAHs were inversely related to or unrelated to elevation. The PAH profiles were similar in soils and leaves from all mountainous regions. Diagnostic ratios showed that the PAHs in soils at different altitudes were from different pollution emission sources; therefore, PAHs in the entire study area were probably derived from mixed sources. Cluster analyses confirmed that liquefied petroleum gas, coal/wood combustion, and petroleum combustion were likely the predominant PAH sources in this region.

Chemometric analysis of ecological toxicants in petrochemical and industrial environments

The application of chemometrics in the assessment of toxicants, such as heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) potentially derived from petrochemical activities in the microenvironment, is vital in providing safeguards for human health of children and adults residing around petrochemical industrial regions. Several multivariate statistical methods are used in geosciences and environmental protection studies to classify, identify and group prevalent pollutants with regard to exhibited trends. Chemometrics can be applied for toxicant source identification, estimation of contaminants contributions to the toxicity of sites of interest, the assessment of the integral risk index of an area and provision of mitigating measures that limit or eliminate the contaminants identified. In this study, the principal component analysis (PCA) was used for dimensionality reduction of both organic and inorganic substances data in the environment, which are potentially hazardous. The high molecular weight (HMW) PAHs correlated positively with stronger impact on the model than the lower molecular weight (LMW) PAHs, the total petroleum hydrocarbons (TPHs), PAHs and BTEX correlate positively in the F1 vs F2 plot indicating similar source contributions of these pollutants in the environmental material. Cu, Cr, Cd, Fe, Zn and Pb all show positive correlation in the same space indicating similar source of contamination. Analytical processes involving environmental assessment data obtained in the Niger Delta area of Nigeria, confirmed the usefulness of chemometrics for comprehensive ecological evaluation.

Polycyclic aromatic hydrocarbons (PAHs) in wetland soils under different land uses in a coastal estuary: toxic levels, sources and relationships with soil organic matter and water-stable aggregates

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in the soils from industrial, wharf, cropland, milldam and natural wetland sites to characterize their distributions, toxic levels and possible sources in the Pearl River Estuary and identify their relationships with soil organic matter (SOM) and water-stable aggregates (WSAs). Our results indicate that the average concentration of total PAHs in this region reached a moderate pollution level, which was higher than that in other larger estuaries in Asia. The average level of total PAHs in industrial soils was 1.2, 1.5, 1.6 and 2.3 times higher than those in soils from wharf, cropland, milldam and natural wetland sites, respectively. Greater accumulation of PAHs occurred in the middle and/or bottom soil layers where 3-ring PAHs were dominant. Industrial soils also exhibited the highest toxic levels with the highest toxic equivalent concentrations of PAHs, followed by wharf and milldam soils, and the cropland and wetland soils had the lowest toxicity. The diagnostic ratios suggested that PAHs primarily originated from biomass and coal combustion at industrial and milldam sites, and petroleum combustion was determined to be the primary source of PAHs at the wharf, cropland and wetland sites. Both 3-ring and 4-ring PAHs in the milldam and wharf soils were significantly positively correlated with the SOM, whereas the 4,5,6-ring PAHs and total PAHs in industrial soils and the 2-ring PAHs in cropland soils were significantly negatively correlated with the SOM. In addition, large WSAs also exhibited a significant positive correlation with PAHs.

Source contributions of PAHs and toxicity in reed wetland soils of Liaohe estuary using a CMB-TEQ method

16 US EPA priority PAHs were analyzed in surface soils collected from reed wetland of Liaohe estuary. Total concentrations of the sixteen PAHs ranged from 235 ng g(-1) to 374 ng g(-1), while the total concentrations of seven carcinogenic PAHs (cPAHs) varied from 82.6 ng g(-1) to 109 ng g(-1). Toxicity of PAHs was assessed using toxic equivalent quantity (TEQ). The BaP and DBahA were the major contributors to TEQBaP, although IND showed the highest concentration level. Quantitative source apportionment of PAHs and toxicity (i.e. TEQBaP) were performed, using the CMB-TEQ (chemical mass balance model and TEQ) method. Results showed that, the vehicular sources (gasoline and diesel engine emissions) yielded a higher contribution to TEQBaP (95.7%) than that to PAHs (57.1%), while petrogenic source and biomass burning, two important contributors for total PAHs (21.6% and 21.3%, respectively), contributed a little to TEQBaP (3.6% and 0.7%, respectively).

Profiles, sources, and transport of polycyclic aromatic hydrocarbons in soils affected by electronic waste recycling in Longtang, south China

We studied the profiles, possible sources, and transport of polycyclic aromatic hydrocarbons (PAHs) in soils from the Longtang area, which is an electronic waste (e-waste) recycling center in south China. The sum of 16 PAH concentrations ranged from 25 to 4,300 ng/g (dry weight basis) in the following order: pond sediment sites (77 ng/g), vegetable fields (129 ng/g), paddy fields (180 ng/g), wastelands (258 ng/g), dismantling sites (678 ng/g), and former open burning sites (2,340 ng/g). Naphthalene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo[b]fluoranthene were the dominant PAHs and accounted for approximately 75 % of the total PAHs. The similar composition characteristics of PAHs and the significant correlations among individual, low molecular weight, high molecular weight, and total PAHs were found in all six sampling site types, thus indicating that PAHs originated from similar sources. The results of both isomeric ratios and principal component analyses confirmed that PAHs were mainly derived from the incomplete combustion of e-waste. The former open burning sites and dismantling sites were the main sources of PAHs. Soil samples that were taken closer to the point sources had high PAH concentrations. PAHs are transported via different soil profiles, including those in agricultural fields, and have been detected not only in 0- to 40-cm-deep soil but also in 40 cm to 80 cm-deep soil. PAH concentrations in soils in Longtang have been strongly affected by primitive e-waste recycling, particularly by former open burning activities.

Polycyclic aromatic hydrocarbons in road-deposited sediments, water sediments, and soils in Sydney, Australia: Comparisons of concentration distribution, sources and potential toxicity

Sixteen polycyclic aromatic hydrocarbons (PAHs) considered as priority environmental pollutants were analysed in surface natural soils (NS), road-deposited sediments (RDS), and water sediments (WS) at Kogarah in Sydney, Australia. Comparisons were made of their concentration distributions, likely sources and potential toxicities. The concentrations (mg/kg) in NS, RDS, and WS ranged from 0.40 to 7.49 (mean 2.80), 1.65 to 4.00 (mean 2.91), and 0.49 to 5.19 (mean 1.76), respectively. PAHs were dominated by relatively high molecular weight compounds with more than three fused benzene rings, indicating that high temperature combustion processes were their predominant sources. The proportions of high molecular weight PAHs with five or six fused benzene rings were higher in NS than in RDS, whereas the low molecular weight PAHs were higher in RDS. Concentrations of all PAHs compounds were observed to be the lowest in WS. The concentrations of most of the high molecular weight PAHs significantly correlated with each other in RDS and WS. All PAHs (except naphthalene) were significantly correlated in NS suggesting a common PAH source. Ratios for individual diagnostic PAHs demonstrated that the primary source of PAHs in WS and NS was of pyrogenic origin (combustion of petroleum (vehicle exhaust), grass, and wood) while in RDS it was petrogenic (i.e. unburned or leaked fuel and oil, road asphalt, and tyre particles) as well as pyrogenic. The potential toxicities of PAHs calculated using a toxicity equivalent quotient (TEQ) were all low but higher for NS compared to WS and RDS.

Biological monitoring of environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage, in Southern China

The study was undertaken to evaluate the environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage in Southern China and research the influence of environment smoke tobacco (EST) to people through active and passive smoking. Urinary concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene were determined in 141 randomly selected voluntary residents aged 13 to 81 years in two polycyclic aromatic hydrocarbon (PAH)-exposed groups, two control groups, and an EST research group. The concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in PAH-exposed groups are significantly higher (p<0.05) than those of control groups. Mean value of 1-hydroxypyrene in the residents living in the area of recycling electronic garbage (1.1 μmol/mol creatinine) is a little higher than those of iron foundry workers, automobile repair workers, and firefighters. Mean value of 2-hydroxynaphthalene (11.3 μmol/mol creatinine) is much higher than that of shipyard and aircraft maintenance and much lower than some occupational exposure, such as coking batteries, sorting department, and distillation department in coking plant. Some metabolites of PAHs (PAHm) are significantly elevated through active and passive smoking, while the influence of EST to other PAHm is not statistically significant. 2-Hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in the urine of smokers are, respectively, 3.9, 1.9, 1.4, and 1.9 times to those of nonsmokers. In nonsmokers, passive smokers excreted 1.1, 1.5, 1.9, and 1.5 times of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene compared to nonpassive smokers.

Distribution and transport of PAHs in soil profiles of different water irrigation areas in Beijing, China

Vertical distribution characteristics and transport mechanisms of polycyclic aromatic hydrocarbons (PAHs) in soil profiles (0-5.5 m) of different water irrigation areas in the southeast suburb of Beijing were analyzed and compared. 16 priority PAHs on the United States Environmental Protection Agency (US EPA) list were analyzed using gas chromatography and mass spectrometry (GC-MS). The relationship between the properties of soil and PAHs was also studied by statistical analyses. The results showed that total PAH concentrations in the topsoils of the wastewater irrigation (WWI) area, reclaimed water irrigation (RWI) area, groundwater irrigation (GWI) area were much higher than those in the deep soils, with the concentrations of 726.0, 206.8 and 42.8 μg kg(-1) (dry wt), respectively. The low molecular weight (LMW) PAHs (2-3 ring) including naphthalene (Nap), phenanthrene (Phe), fluorene (Fl) dominated the layers (0.5-5.5 m) underneath the surfaces. The migration of LMW PAHs was faster than that of high molecular weight (HMW) PAHs and LMW PAHs were transported in dissolved matter. The different soil textures of three sites caused the differences in the variation ranges of PAHs in the profiles. The statistical analyses showed a significant linear positive correlation between PAHs and total organic carbon (TOC). The 2-4 ring PAHs were detected in the wastewater and reclaimed waters, which was consistent with those in the soil profiles. The presence of PAHs in the soil profiles was mainly due to the irrigation of wastewater. Wastewater reuse guidelines and standards for irrigation should be established urgently.

Accumulation and risks of polycyclic aromatic hydrocarbons and trace metals in tropical urban soils

The study deals with the combined contribution of polycyclic aromatic hydrocarbons (PAHs) and metals to health risk in Delhi soils. Surface soils (0-5 cm) collected from three different land-use regions (industrial, flood-plain and a reference site) in Delhi, India over a period of 1 year were characterized with respect to 16 US Environmental Protection Agency priority PAHs and five trace metals (Zn, Fe, Ni, Cr and Cd). Mean annual ∑16PAH concentrations at the industrial and flood-plain sites (10,893.2 ± 2826.4 and 3075.4 ± 948.7 μg/kg, respectively) were ~15 and ~4 times, respectively, higher than reference levels. Significant spatial and seasonal variations were observed for PAHs. Toxicity potentials of industrial and flood-plain soils were ~88 and ~8 times higher than reference levels. Trace metal concentrations in soils also showed marked dependencies on nearness to sources and seasonal effects. Correlation analysis, PAH diagnostic ratios and principal component analysis (PCA) led to the identification of sources such as coal and wood combustion, vehicular and industrial emissions, and atmospheric transport. Metal enrichment in soil and the degree of soil contamination were investigated using enrichment factors and index of geoaccumulation, respectively. Health risk assessment (incremental lifetime cancer risk and hazard index) showed that floodplain soils have potential high risk due to PAHs while industrial soils have potential risks due to both PAHs and Cr.

Polycyclic aromatic hydrocarbons (PAHs) in soils from a multi-industrial city, South Korea

We collected soil samples at 25 sites in Ulsan, Korea to investigate the levels, patterns, spatial distribution, and sources of polycyclic aromatic hydrocarbons (PAHs) in the summer 2010. The target compounds were the 16 US-EPA priority PAHs. For the source identification of PAHs, diagnostic ratios and the positive matrix factorization (PMF) model were used. The total concentrations of PAHs ranged from 65 ng/g to 12,000 ng/g (mean: 960 ng/g, median 330 ng/g). The levels and distribution of PAHs indicated that industrial areas were more polluted than rural and urban areas. The diagnostic ratios suggested that the soil samples were contaminated by pyrogenic sources and traffic emission. According to the result of PMF, four factors were identified: gasoline and heavy oil combustion (14%), diesel combustion (54%), coke oven (23%), and coal/biomass burning (9%). Therefore, it was concluded that vehicles and industrial complexes were major sources of PAHs in Ulsan.

Polycyclic aromatic hydrocarbons in surface soil across the Tibetan Plateau: spatial distribution, source and air-soil exchange

There are limited data on polycyclic aromatic hydrocarbons (PAHs) in both the atmosphere and soil of the Tibetan Plateau (TP). Concentrations of PAHs were therefore measured in 13 XAD resin-based passive air samplers and 41 surface (0-5 cm) soil samples across the TP. The average concentration of atmospheric PAHs was 5.55 ng/m(3), which was lower than that reported for other background areas, but higher than the Arctic. Concentrations in the soils fell in a wide range from 5.54 to 389 ng/g, with an average of 59.9 ng/g. Elevation was found to play an important role in determining the spatial distribution of soil PAHs. The air-soil exchange state showed that the soils of the TP will likely remain as a sink for high molecular weight PAHs, but may become a potential "secondary source" for low molecular weight PAHs.

Concentrations and geographic distribution of selected organic pollutants in Scottish surface soils

Concentrations of selected persistent organic pollutants (POPs) representing three chemical classes (polycyclic aromatic hydrocarbons (PAH), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) and the organic pollutant diethylhexyl phthalate (DEHP), were determined in surface soil samples (0-5 cm) collected at 20 km grid intersects throughout Scotland over a three-year period. Detectable amounts of all chemical classes and most individual congeners were present in all samples. There were no consistent effects of soil or vegetation type, soil carbon content, pH, altitude or distance from centres of population on concentrations which exhibited extreme variation, even in adjacent samples. It is concluded that soil POPs and DEHP concentrations and associated rates of animal and human exposure were highly variable, influenced by multiple, interacting factors, and not clearly related to local sources but possibly related to wet atmospheric deposition and the organic carbon content of the soil.

Polycyclic aromatic hydrocarbons in soils along the coastal and estuarine areas of the northern Bohai and Yellow Seas, China

Polycyclic aromatic hydrocarbons (PAHs) and their health risks in surface soils (n = 31) collected from coastal and estuarine areas of the northern Bohai and Yellow Seas (CEANBYS), China, were investigated. Total concentrations of PAHs ranged from 6.6 × 10(1) to 9.2 × 10(2) ng g(-1) dry weight, with an average of 3.1 × 10(2) ng g(-1) dw. The locations where greater concentrations of PAHs were observed were all near factories emitting black smoke or on the edge of the urban areas. These observations are consistent with concentrations of PAHs in soils being influenced by human activities, especially industrialization and urbanization. Concentrations of PAHs were significantly correlated with concentrations of organic carbon in soils. The patterns of relative concentrations and types of PAHs observed as well as knowledge of the potential sources were consistent with the primary sources of PAHs in soils of the CEANBYS being derived from the pyrolytic processes such as combustion of fossil fuel. The incremental lifetime cancer risks of exposing to PAHs for child, youth, and adult were 1.6 × 10(-6), 1.2 × 10(-6), and 1.9 × 10(-6).

Multi-factors influencing the spatial distribution of polycyclic aromatic hydrocarbons in soils surrounding drinking water protection zone

We selected the Guanting Reservoir in Beijing, China as a case where an industrial area locates on the upwind corner to study the influence of human activities and natural processes on the distribution of polycyclic aromatic hydrocarbons (PAHs) in soils. Soil PAH concentrations in the study area follow a log-normal probability distribution function, suggesting that distribution of PAH in soils was affected by human activities. Distribution of PAHs in soils was significantly affected by the point source that high PAH concentrations were observed in near industrial area with an obvious declining trend from the northwest to the southeast which was the prevailing wind direction in this area. Away from the influence of point source, distribution of PAHs in soils was found to significantly correlate with total organic carbon content, while the influences of agricultural land uses and type of soil texture on the total soil PAHs contents and ring compositions were quite limited. The results can provide some evidences and data on the pollutant accumulation in drink water protection area influenced by natural processes and human activities.

Polycyclic aromatic hydrocarbons in soils from Urumqi, China: distribution, source contributions, and potential health risks

Concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were measured in 28 surface soils samples collected from Urumqi, northwest China, for examination of distributions, source contributions, and potential health effects. The results indicated that the sum of 16 PAHs concentration ranged from 331 to 15,799 μg kg(-1) (dw) in soils, with a mean of 5,018 ± 4,896 μg kg(-1) (n = 28). The sum of seven carPAHs concentration ranged from 4 to 1,879 μg kg(-1) (dw; n = 28). The highest ∑PAHs concentrations were found at roadsides and industrial sites, followed by those at parks, rural areas, and business/residential areas. Coal combustion, emission of diesel and gasoline from vehicles, and petroleum source were four sources of PAHs as determined by PMF analysis, which contributed 51.19, 19.02, 18.35, and 11.42% to the PAH sources, respectively. Excellent coefficients of correlation between the measured and predicted PAHs concentrations suggested that the PMF model was very effective to estimate sources of PAHs in soils. Incremental lifetime cancer risk values at the 95th percentile due to human exposure to surface soils PAHs in Urumqi were 2.02 × 10(-6) for children and 2.72 × 10(-5) for adults. The results suggested that the current PAHs levels in soils from Urumqi were pervasive and moderately carcinogenic to children and adults.

Composition, sources, and potential toxicology of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils in Liaoning, People's Republic of China

Surface soil (0-20 cm) samples (n = 143) were collected from vegetable, maize, and paddy farmland used for commercial crops in Liaoning, China. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) listed in US Environmental Protection Agency were analyzed by high-performance liquid chromatography using a fluorescence detector. The soil concentrations of the 16 PAH ranged from 50 to 3,309 ng/g with a mean of 388 ng/g. The highest concentration of total PAHs found in soil of the vegetable farmland was 448 ng/g in average, followed by maize and paddy with total PAHs of 391 and 331 ng/g, respectively. Generally, the low molecular weight PAHs were more predominant than the high molecular weight PAHs in most of the soils. The evaluation of soil PAH contamination based on the Canadian criterion indicated that only naphthalene, phenanthrene, and pyrene were over the target values in several sampling sites. Isomer pair ratios and principal component analysis indicated that biomass and coal combustion were the main sources of PAHs in this area. And the average value of total B[a]Peq concentration in vegetable soils was higher than paddy and maize soils. We suggest that biomass burning should be abolished and commercial farming should be carried out far from the highways to ensure the safety of food products derived from commercial farming.

Exposure to traffic emissions: associations with biomarkers of antioxidant status and oxidative damage

BACKGROUND

Oxidative stress has been implicated as a possible mechanism for adverse health effects associated with traffic emissions. We examined the association of an estimate of traffic emissions with blood biomarkers of antioxidant capacity (glutathione, glutathione peroxidase, trolox-equivalent antioxidant capacity) and oxidative damage (thiobarbituric acid-reactive substances (TBARS)) among 1810 healthy women, randomly selected from Erie and Niagara Counties in Western New York.

METHODS

A geographic traffic emission and meteorological dispersion model was used to estimate annual polycyclic aromatic hydrocarbon (PAH) exposure from traffic emissions for each woman based on her residence at the time of study. Associations of traffic-related PAH exposure with measures of oxidative stress and antioxidant capacity were examined in multiple regression analyses with adjustment for potential confounders.

RESULTS

Higher traffic-related PAH exposure was associated with decreased glutathione and increased glutathione peroxidase. Stronger associations between traffic-related PAH exposure and levels of glutathione and glutathione peroxidase were suggested among nonsmoking women without secondhand smoke exposure, especially among premenopausal nonsmoking women. Associations were also stronger for measurements made in warmer months.

CONCLUSIONS

These findings suggest that PAHs or other components of traffic emissions may impact anti-oxidative capacity among healthy women, particularly premenopausal non-smokers without secondhand smoke exposure.

Polycyclic aromatic hydrocarbons (PAHs) in soils and vegetation near an e-waste recycling site in South China: concentration, distribution, source, and risk assessment

This study determined the concentrations of PAHs generated from e-waste recycling activities and their potential impacts on soil, vegetation, and human health. The total PAH concentrations in soils and plants ranged from 127 to 10,600 and 199 to 2420 ng/g, respectively. Samples from an e-waste burning site had higher PAH concentrations than samples from adjacent locations. The PAHs in plants varied with plant species and tissue, and Lactuca sativa L. contained the highest PAHs of all the vegetable species. Various land use types showed different PAH concentrations in soils, with vegetable fields showing higher concentrations than paddy fields. Low molecular weight PAHs, such as phenanthrene, were the predominant congeners in soils, whereas high molecular weight PAHs, such as fluoranthene, pyrene, and benzo[a]anthracene, were enriched in plants relative to soils. Dissimilar PAH profiles in soil and the corresponding vegetation indicated that the uptake of PAHs by plants was selective. A source analysis showed that the contamination by PAHs originated primarily from the open burning of e-waste. The total daily intakes of PAHs and carcinogenic PAHs through vegetables at the e-waste dismantling site were estimated to be 279 and 108 ng/kg/d, respectively, indicating that the consumption of vegetables grown near e-waste recycling sites is risky and should be completely avoided.

Distribution, Sources, and Association of Polycyclic Aromatic Hydrocarbons, Black Carbon, and Total Organic Carbon in Size-Segregated Soil Samples Along a Background-Urban-Rural Transect

Soil samples were collected over a year-long period along a background-urban-rural transect in Delhi, India for the analysis of polycyclic aromatic hydrocarbons (PAHs), black carbon (BC), and total organic carbon (TOC) in five grain size fractions, x, in μm of 0≤x<53 (I), 53≤x<250 (II), 250≤x<500 (III), 500≤x<2000 (IV), and their sum (total: T). Maximum concentrations of PAH, BC, and TOC were observed in the smallest fraction (I) comprising silt and clay, irrespective of site or season. Results of the molecular diagnostic ratios and principal component analysis (PCA) identified coal, wood, biomass burning, and vehicular emissions as major sources of PAHs at all the three sites, while BC/TOC ratios pointed toward biomass combustion as the chief source of carbonaceous species. This work presents the first such rural-urban transect study considering PAH, BC, and TOC in soil.

Risk assessment and sources of polycyclic aromatic hydrocarbons in agricultural soils of Huanghuai plain, China

The profiles and sources of polycyclic aromatic hydrocarbons (PAHs) were analyzed in 227 agricultural surface soils from the Huanghuai plain, China. The total concentrations of 16 PAHs varied from 15.7 to 1247.6 μg/kg, with an average of 129.5 μg/kg. Compared with pollution level and carcinogenic potential risk in other research, the soil PAH concentrations in this study fell within low to middle level. Unexpectedly, a significant correlation was not observed between the PAH concentration in soils and the corresponding content of the soil organic matter. This is partly interpreted for our sampling sites located in agricultural area where fresh input of organic fertilizers is expected. Principal component analysis-multiple linear regression suggests that low temperature combustion, coal combustion and traffic emissions could be the primary PAH contributors in soils from the Huanghuai plain, accounting for 46.7 percent, 42.1 percent and 11.2 percent of PAH concentrations, respectively.

Multivariate analysis of mixed contaminants (PAHs and heavy metals) at manufactured gas plant site soils

Principal component analysis (PCA) was used to provide an overview of the distribution pattern of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in former manufactured gas plant (MGP) site soils. PCA is the powerful multivariate method to identify the patterns in data and expressing their similarities and differences. Ten PAHs (naphthalene, acenapthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]pyrene) and four toxic heavy metals - lead (Pb), cadmium (Cd), chromium (Cr) and zinc (Zn) - were detected in the site soils. PAH contamination was contributed equally by both low and high molecular weight PAHs. PCA was performed using the varimax rotation method in SPSS, 17.0. Two principal components accounting for 91.7% of the total variance was retained using scree test. Principle component 1 (PC1) substantially explained the dominance of PAH contamination in the MGP site soils. All PAHs, except anthracene, were positively correlated in PC1. There was a common thread in high molecular weight PAHs loadings, where the loadings were inversely proportional to the hydrophobicity and molecular weight of individual PAHs. Anthracene, which was less correlated with other individual PAHs, deviated well from the origin which can be ascribed to its lower toxicity and different origin than its isomer phenanthrene. Among the four major heavy metals studied in MGP sites, Pb, Cd and Cr were negatively correlated in PC1 but showed strong positive correlation in principle component 2 (PC2). Although metals may not have originated directly from gaswork processes, the correlation between PAHs and metals suggests that the materials used in these sites may have contributed to high concentrations of Pb, Cd, Cr and Zn. Thus, multivariate analysis helped to identify the sources of PAHs, heavy metals and their association in MGP site, and thereby better characterise the site risk, which would not be possible if one uses chemical analysis alone.

Comparative evaluation of environmental contamination and DNA damage induced by electronic-waste in Nigeria and China

In the last decade, China and Nigeria have been prime destinations for the world's e-waste disposal leading to serious environmental contamination. We carried out a comparative study of the level of contamination using soils and plants from e-waste dumping and processing sites in both countries. Levels of polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were analyzed using gas chromatography/spectrophotometry and heavy metals using atomic absorption spectrophotometry. DNA damage was assayed in human peripheral blood lymphocytes using an alkaline comet assay. Soils and plants were highly contaminated with toxic PAHs, PCBs, PBDEs, and heavy metals in both countries. Soil samples from China and plant samples from Nigeria were more contaminated. There was a positive correlation between the concentrations of organics and heavy metals in plant samples and the surrounding soils. In human lymphocytes, all tested samples induced significant (p<0.05) concentration-dependent increases in DNA damage compared with the negative control. These findings suggest that e-waste components/constituents can accumulate, in soil and surrounding vegetation, to toxic and genotoxic levels that could induce adverse health effects in exposed individuals.

County-scale distribution of polycyclic aromatic hydrocarbons in topsoil of the Yellow River Delta Region

The Yellow River Delta (YRD) is a typical agricultural and petrochemical industrial area in China. To assess the current status of polycyclic aromatic hydrocarbons (PAHs) of soil residues, soil samples (0-15 cm) (n = 82) were collected in Bincheng District, at the geographic center of the YRD. Concentrations of 16 PAHs (∑PAHs) ranged from 181.1 to 2176.0 μg kg(-1), with an average concentration of 359.8 μg kg(-1), showing significant increase along a rural-urban gradient (p ≤ 0.05). The contribution of naphthalene and phenanthrene to ∑PAHs was 48.6-57.6 %, and the contribution of low molecular weight (two- and three-ring) PAHs was 56.3-66.4 % from urban to rural. The significant correlations between ∑PAHs and soil organic C and total N concentrations were observed (p ≤ 0.05), indicated soil organic C and total N can affect PAH distribution in the study area, especially for low molecular weight PAHs. Principal component and multiple linear regression analysis reveal that soil PAHs have different sources in different area. Various petroleum inputs (volatilization, vehicular and non-vehicle combustion) were the main sources of soil PAHs in the urban and suburban areas, and the main source was biomass burning in the rural. In general, most soil PAH contaminations in the study area were classified as weakly polluted. Even so, soil PAH contamination from petroleum, particularly near petrochemical production sites, deserves further attention, because lighter PAH compounds are more labile and can react with other pollutants to form more toxic derivates.

Chemometric application in identifying sources of organic contaminants in Langat river basin

Increasing urbanization and changes in land use in Langat river basin lead to adverse impacts on the environment compartment. One of the major challenges is in identifying sources of organic contaminants. This study presented the application of selected chemometric techniques: cluster analysis (CA), discriminant analysis (DA), and principal component analysis (PCA) to classify the pollution sources in Langat river basin based on the analysis of water and sediment samples collected from 24 stations, monitored for 14 organic contaminants from polycyclic aromatic hydrocarbons (PAHs), sterols, and pesticides groups. The CA and DA enabled to group 24 monitoring sites into three groups of pollution source (industry and urban socioeconomic, agricultural activity, and urban/domestic sewage) with five major discriminating variables: naphthalene, pyrene, benzo[a]pyrene, coprostanol, and cholesterol. PCA analysis, applied to water data sets, resulted in four latent factors explaining 79.0% of the total variance while sediment samples gave five latent factors with 77.6% explained variance. The varifactors (VFs) obtained from PCA indicated that sterols (coprostanol, cholesterol, stigmasterol, β-sitosterol, and stigmastanol) are strongly correlated to domestic and urban sewage, PAHs (naphthalene, acenaphthene, pyrene, benzo[a]anthracene, and benzo[a]pyrene) from industrial and urban activities and chlorpyrifos correlated to samples nearby agricultural sites. The results demonstrated that chemometric techniques can be used for rapid assessment of water and sediment contaminations.

Contamination, source identification, and risk assessment of polycyclic aromatic hydrocarbons in agricultural soil of Shanghai, China

The level, distribution, compositional pattern, and possible sources of polycyclic aromatic hydrocarbons (PAHs) in agricultural soil of Shanghai were investigated. The concentrations ranged from 140.7 to 2,370.8 μg kg( -1) for 21 PAHs and from 92.2 to 2,062.7 μg kg( -1) for 16 priority PAHs, respectively. The higher level of PAHs was mainly distributed in the south and west of Shanghai region, and the lower concentration was found in Chongming Island. Generally, the composition pattern of PAHs was characterized with high molecular weight PAHs, the seven possible carcinogenic PAHs accounted for 4.8-50.8% of the total PAHs, and fluoranthene, pyrene, and benzo[b]fluoranthene were the most dominant components in soil samples. The correlation analysis suggested that low molecular weight PAHs and high molecular weight PAHs were originated from different sources and further corroborated that total organic carbon was a key soil property affecting the fate of persistent organic pollutants in the environment. The isomer ratios and principal component analysis indicated that PAHs in the investigated areas were derived primarily from combustion of biomass, coal, and petroleum. Compared to the soil quality standards of the Netherlands, all the target PAHs (except Ant) in most samples exceeded their target values. The Nemerow composite index based on the same soil quality standard showed that 69.4% of the soil samples were heavily polluted. The total BaP(eq) of ten Dutch target PAHs in 72% soil samples were higher than the reference total carcinogenic potency. Therefore, the agricultural soil in Shanghai is suffering from serious PAHs contamination.

Polycyclic aromatic hydrocarbons (PAHs) in urban surface dust of Guangzhou, China: Status, sources and human health risk assessment

Ninety-six urban surface dust samples collected from Guangzhou, a typical urban center in South China, were analyzed for 16 PAHs (2-6 rings). ∑PAHs concentrations in the urban surface dust ranged from 0.84 to 12.3μg/g with a mean of 4.80μg/g. High molecular weight compounds (4-6 rings) contributed to 62 to 94% of ∑PAHs mass in the surface dust samples. Four hotspots with highest ∑PAHs were identified via kriging prediction mapping, representing the highly-urbanized regions: central downtown, highway and industrial area. Two major origins of PAHs inputs to urban surface dust were identified as vehicle emissions (51.9%) and coal combustion (26.8%). The 95% UCL of Incremental Lifetime Cancer Risk (ILCR) due to human exposure to urban surface dust PAHs in central South China was 3.03×10(-6) for children and 2.92×10(-6) for adults.

Major pollutants in soils of abandoned agricultural land contaminated by e-waste activities in Hong Kong

Polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyl (PCB), polybrominated diphenyl ether (PBDE) compounds and five heavy metals (cadmium, copper, chromium, lead, and zinc) were determined in soil samples collected from six sites of abandoned agricultural land affected by electronic-waste: e-waste dismantling workshop [EW (DW)], e-waste open burning site [EW (OBS)], e-waste storage [EW (S)], and agricultural (A) in the New Territories, Hong Kong. Persistent organic pollutants (POPs) and heavy metals were detected in all soil samples. EW (DW) contained the highest concentrations of PAHs, Cr, Cu, and Zn, whereas EW (OBS) had the highest concentrations of PCBs, PBDEs, Cd, and Pb. PAH at EW (DW) and EW (OBS) and PCB concentrations at EW (OBS) exceeded the target values of the New Dutch list, whereas Cd, Cu, Cr, Pb, and Zn levels exceeded the Chinese legislation for the protection of agricultural production and safeguarding of human health, by 3-11 times at EW (OBS) and 5-8 times at EW (DW). Lead at EW (OBS) and EW (DW) and Cr at EW (DW) greatly exceeded the Canadian Soil Quality Guidelines by 46 and 20 times and 27 times, respectively. Concentrations of POPs and heavy metals at EW (DW) and EW (OBS) were significantly higher than at EW (S) and A. It was concluded that e-waste activities led to increases of toxic chemicals at these abandoned agricultural land, which would hinder the redevelopment of the land.

Effects of phenanthrene on the mortality, growth, and anti-oxidant system of earthworms (Eisenia fetida) under laboratory conditions

To assess the toxic effects of phenanthrene on earthworms, we exposed Eisenia fetida to artificial soils supplemented with different concentrations (0.5, 2.5, 12.5, mgkg(-1) soil) of phenanthrene. The residual phenanthrene in the soil, the bioaccumulation of phenanthrene in earthworms, and the subsequent effects of phenanthrene on growth, anti-oxidant enzyme activities, and lipid peroxidation (LPO) were determined. The degradation rate of low concentrations of phenanthrene was faster than it was for higher concentrations, and the degradation half-life was 7.3d (0.5 mgkg(-1)). Bioaccumulation of phenanthrene in the earthworms decreased the phenanthrene concentration in soils, and phenanthrene content in the earthworms significantly increased with increasing initial soil concentrations. Phenanthrene had a significant effect on E. fetida growth, and the 14-d LC(50) was calculated as 40.67 mgkg(-1). Statistical analysis of the growth inhibition rate showed that the concentration and duration of exposure had significant effects on growth inhibition (p<0.001). Superoxide dismutase (SOD) activity increased at the beginning (2 and 7d) and decreased in the end (14 and 28 d). Catalase (CAT) activity in all treatments was inhibited from 1 to 14 d of exposure. However, no significant perturbations in malondialdehyde (MDA) content were noted between control and phenanthrene-treated earthworms except after 2d of exposure. These results revealed that bioaccumulation of phenanthrene in E. fetida caused concentration-dependent, sub-lethal toxicity. Growth and superoxide dismutase activity can be regarded as sensitive parameters for evaluating the toxicity of phenanthrene to earthworms.

Levels, distribution and source characterization of polycyclic aromatic hydrocarbons (PAHs) in topsoils and roadside soils in Esbjerg, Denmark

A soil survey was performed to determine the levels, distributions and sources of 6 polycyclic aromatic hydrocarbons (PAHs) in 9 selected soil environments in Esbjerg, Denmark. In all, 24 soil samples were collected and the PAHs present were extracted with dichloromethane and analysed using GC/MS/MS with ion trap detector (TCD). There were elevated levels of the individual as well as the total PAHs in the soil samples and also, all 6 PAHs were present in all the soil samples. The most abundant components were fluoranthene, benzo(b)fluoranthene and benzo(a)pyrene. The average sum of the 6 PAHs in all soil samples was 2.5 mg.kg(-1), with range from 0.24 to 7.6 mg kg(-1). The total mean PAH concentration obtained was 1.67 times higher than the total limit set by the Danish Environmental Protection Agency (DEPA) whiles the mean benzo(a)pyrene (BaP) concentration (0.6 mg kg(-1)) also 6 times the Soil Quality Criteria (Human Health) (0.1 mg kg(-1)) by DEPA and 2 times the Maximum Permissible Concentrations (0.26 mg kg(-1)) by the Netherlands for BaP. This shows that there are elevated levels of PAH deposition on the Esbjerg soil environment which needs an urgent attention. The diagnostic ratios and the correlation analysis identified mixed petrogenic and pyrogenic sources as the main contributors of PAHs on the Esbjerg environment.

Particle-phase dry deposition and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in Izmir, Turkey

Ambient air and dry deposition samples were collected at suburban and urban sites in Izmir, Turkey. Atmospheric total (particle+gas) ∑(14)PAHs concentrations were 36±39 and 144±163 ng m(-3) for suburban and urban sites, respectively. Phenanthrene was the most abundant compound at all sites, and all samples were dominated by low molecular weight PAHs. Average particulate ∑(14)PAH dry deposition fluxes were 8160±5024 and 4286±2782 ng m(-2) day(-1) and overall average particulate dry deposition velocities were 1.5±2.4 and 1.0±2.3 cm s(-1) for suburban and urban sites, respectively. Soil samples were collected at suburban site. Average soil concentration for ∑(14)PAH was 55.9±14.4 ng g(-1) dry weight. Calculated gas-phase air-soil exchange fluxes indicated that fluorene, phenanthrene, anthracene, and carbazole were deposited to soil in winter while they were volatilized in summer. Other compounds (fluoranthene-benzo[g,h,i]perylene) were deposited to soil in both periods. Annual average fluxes of PAHs representing soil to air (i.e., gas volatilization) and air to soil transfer (i.e., gas absorption, dry deposition, and wet deposition) processes were also compared. All processes were comparable for Σ(14)PAHs however their input was dominated by gas absorption. Gas absorption dominated for lower molecular weight PAHs, however dry deposition dominated for higher molecular weight PAHs. The results have suggested that for fluorene, soil and air may be approaching a steady state condition. For the remaining compounds, there was a net accumulation into the soil.

Soil pollution by polycyclic aromatic hydrocarbons: a comparison of two Chinese cities

Soil samples from Huizhou and Zhanjiang, China were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) with harmonized sampling, sample extraction and analysis quantification methods. The concentrations and sources of PAHs in soil samples of the two cities were compared. Almost all of the PAH components were detectable in 103 soil samples. The concentrations of sigmaPAHs ranged from 35.40 to 534.5 microg/kg in soil samples from Huizhou, and ranged from 9.50 to 6618.00 microg/kg in samples from Zhanjiang. Evident differences of concentrations, compositions and sources of PAHs in soils were observed between the two cities. The average concentrations of individual component and the sum of a group of PAHs in soil samples from Zhanjiang were significantly higher than those in Huizhou (P < 0.05). Phe, Flu, Pyr, Bbf and Baa were the dominant PAH components both in soil samples from Huizhou and Zhanjiang. Except for these five components, Bap, I1p, Daa and Bgp were also the dominant PAH components in soil samples from Zhanjiang. Coal combustion and liquid fossil fuel combustion were the same sources of PAHs in the two cities with different contributions, and petroleum played a key role in PAHs release in Zhanjiang.

Enrichment of polycyclic aromatic hydrocarbons (PAHs) in mariculture sediments of Hong Kong

Surface and core sediments collected from six fish farms in Hong Kong and from reference sites were investigated for the enrichment and sources of polycyclic aromatic hydrocarbons (PAHs). Moderately high SigmaPAH16 levels (123-947 ng g(-1), mean: 450 ng g(-1)) were found in the surface aquaculture sediments. In comparison with the sediments from the reference sites, the average enrichment percentage of total organic carbon (TOC) and PAHs in surface sediments were 21.4 and 43.8%, respectively, and in the core sediments, 24.6 and 73.7%, respectively. Mathematical source apportionment analyses (i.e. isomer ratios, hierarchical cluster analysis, principal components analysis with multiple linear regression analysis) suggested a higher percentage of petrogenic sources in aquaculture sediments. The fish feeds might be the main source of the enriched PAHs in the aquaculture sediments. To our knowledge, this is the first study showing that PAHs in aquaculture sediments could be attributed to human aquaculture activities.

Characterization of PAHs in surface sediments of aquaculture farms around the Pearl River Delta

The distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of freshwater fishponds and mariculture rafts around the Pearl River Delta (PRD) were investigated. Twenty-one sample sites were chosen, consisting of fifteen freshwater fishponds and six mariculture rafts. The total PAH ( summation SigmaPAH) concentrations measured in all the sediment samples ranged from 52.7 to 717 ng g(-1), with mean of 184 ng g(-1). The marine sediment samples contained higher levels of summation SigmaPAH, high molecular weight (HMW) PAHs and carcinogenic PAHs than freshwater sediments (p<0.05). Principal component analysis/multiple linear regression analysis (PCA/MLRA) indicated that the source of PAHs in freshwater sediment was mainly derived from mixed combustion of coal, wood, and vehicle emission (66.2%). Vehicle emissions and coal combustion were the main sources (52.5 and 47.5% of summation SigmaPAH, respectively) of PAHs contaminated in the marine sediments. The present study indicated that surface sediments of freshwater fishponds and mariculture rafts around the PRD were grossly contaminated by PAHs derived from combustion sources.

Concentrations, sources and spatial distribution of polycyclic aromatic hydrocarbons in soils from Beijing, Tianjin and surrounding areas, North China

The concentrations, profiles, sources and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) were determined in 40 surface soil samples collected from Beijing, Tianjin and surrounding areas, North China in 2007, and all sampling sites were far from industrial areas, roadsides and other pollution sources, and across a range of soil types in remote, rural villages and urban areas. The total concentrations of 16 PAHs ranged from 31.6 to 1475.0 ng/g, with an arithmetic average of 336.4 ng/g. The highest PAH concentrations were measured in urban soils, followed by rural village soils and soils from remote locations. The remote-rural village-urban PAH concentration gradient was related to population density, gross domestic product (GDP), long-range atmospheric transport and different types of land use. In addition, the PAH concentration was well correlated with the total organic carbon (TOC) concentration of the soil. The PAH profile suggested that coal combustion and biomass burning were primary PAH sources.

Black carbon in urban topsoils of Xuzhou (China): environmental implication and magnetic proxy

Combustion-derived black carbon has received attention as a form of refractory organic carbon that may be preferentially preserved in soils and sediments. However, little is understood about the environmental roles of black carbon in urban soils. This investigation represented the preliminary study to characterize black carbon (BC) concentrations and enrichment ratios in Xuzhou urban roadside topsoil. Data from 21 roadside topsoil samples showed that the median of BC concentrations is 21.8 mg/g, which is significantly higher than local background value that averages 3.8 mg/g. Hierarchical clustering analysis indicated that BC in Xuzhou urban roadside soils are mainly from the traffic emissions. The marked positive correlations between BC and the concentrations of heavy metals (Pb, Cu, Zn, Mo, and Sc; Pearson correlation coefficient, 0.623, 0.809, 0.846, 0.742 and 0.831, respectively) suggested that these heavy metals are likely to be strongly retained by BC present in roadside topsoil. The significant positive correlation between BC and specific magnetic susceptibility was also observed. Thus, the simple environmental magnetic method is potentially an efficient alternative technique for assessing BC concentration in roadside topsoil.

Levels and distributions of polycyclic aromatic hydrocarbons in agricultural soils in an emerging e-waste recycling town in Taizhou area, China

The present study investigated the levels, distributions, profiles and possible sources of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils around Zeguo, an emerging e-waste recycling town in Taizhou area, China. Concentrations of sixteen USEPA priority PAHs and soil organic matter were analyzed in 59 agricultural soil samples. The total PAH concentrations ranged from 262.6 to 3,420.2 microg/kg, with the average values in a gradually descending order: agricultural soil near e-waste recycling plants and workshops (1,336.0 microg/kg) > agricultural soil in villages with open burning and e-waste recycling activities (945.8 microg/kg) > agricultural soil in other villages (466.5 microg/kg). Analysis of the distribution patterns of the PAHs showed that phenanthrene, anthracene, fluoranthene and pyrene were the dominant species. The significant correlations among individual, low-molecular-weight (LMW), high-molecular-weight (HMW) and total PAHs and the very similar PAH profiles in the three sampling areas indicated that the PAHs might have come from similar sources. The ratios of Anthracene to sum of Anthracene and Phenanthrene concentrations (Ant/(Ant+Phe)) and fluoranthene to sum of fluoranthene and pyrene concentrations (Flt/(Flt+Pyr)) were calculated and principal component analysis (PCA) was performed and the results suggested that an anthropogenic source such as the combustion of a petroleum product or coal during the e-waste recycling process seemed to be the main source of PAHs in the Zeguo agricultural soil. In conclusion, soils taken from Zeguo agricultural areas were considered to be heavily polluted, and the emerging e-waste recycling activities had definite effects on PAH soil concentrations.

The polycyclic aromatic hydrocarbon concentrations in soils in the Region of Valasske Mezirici, the Czech Republic

The polycyclic aromatic hydrocarbon (PAH) contamination of urban, agricultural and forest soil samples was investigated from samples obtained in the surroundings of Valasske Mezirici. Valasske Mezirici is a town located in the north-east mountainous part of the Czech Republic, where a coal tar refinery is situated. 16 PAHs listed in the US EPA were investigated. Organic oxidizable carbon was also observed in the forest soils. The PAH concentrations ranged from 0.86-10.84 (with one anomalous value of 35.14) and 7.66-79.39 mg/kg dm in the urban/agricultural and forest soils, respectively. While the PAH levels in the urban/agricultural soils are within the range typically found in industrialized areas, the forest soils showed elevated PAH concentrations compared to other forest soils in Western and Northern Europe. The PAH concentrations and their molecular distribution ratios were studied as functions of the sample location and the meteorological history. The soils from localities at higher altitudes above sea level have the highest PAH concentrations, and the PAH concentrations decrease with increasing distance from the town.