Uptake, translocation, and risk assessment of PAHs in contaminated soil-air-vegetable systems based on a field simulation experiment.

Vegetable consumption is a potential toxin exposure pathway for humans. Studies have recognized that vegetables can uptake organic contaminants via roots and translocate pollutants to their aerial parts. However, the aerial parts might also directly uptake polycyclic aromatic hydrocarbons (PAHs) from contaminated soils. This has not been extensively studied. The aim of this study was to explore the uptake and translocation of PAHs in contaminated soil-air-vegetable systems. Sixteen individual PAHs in contaminated soils, vegetable roots, and leaves were identified using GC-MS. The results showed that the average PAH concentrations both in roots and leaves from the reference soil, the moderately contaminated soil, and the heavily polluted soil increased as expected. PAHs with log KOW < 5 accumulated more easily in roots and leaves. Using a Pearson correlation analysis, isomer ratios, and a principal component analysis (PCA), it was found that the contaminated soil not only caused PAH accumulation in roots, but also increased the PAH concentration in leaves. Quantitatively, the absorption of PAHs in roots in the moderately contaminated soil (70.3 ng m-3) was approximately twice that of the reference soil (40.8 ng m-3). The PAHs absorbed by vegetable roots in the heavily polluted soil (74.7 ng m-3) was only slightly higher than that of the moderately polluted soil. In addition, the PAH dose volatilized into the air from the reference soil, the moderately contaminated soil, and the heavily polluted soil also showed an increasing trend. The incremental lifetime cancer risk (ILCR) indicated that adult females had a higher cancer risk via vegetable consumption than other groups. Although vegetable consumption had a slight effect on cancer risk for some groups in the present study, the cancer risk of PAHs caused by eating vegetables grown in heavily contaminated soil still requires attention.

Characterization of polycyclic aromatic hydrocarbons (PAHs) in vegetables near industrial areas of Shanghai, China: Sources, exposure, and cancer risk.

Dietary consumption of contaminated vegetables may contribute to polycyclic aromatic hydrocarbon (PAH) exposure in humans; however, this exposure pathway has not been examined thoroughly. This study aims to characterize the concentrations of PAHs in six types of vegetables grown near industrial facilities in Shanghai, China. We analyzed 16 individual PAHs on the US EPA priority list, and the total concentration in vegetables ranged from 65.7 to 458.0 ng g-1 in the following order: leafy vegetables (romaine lettuce, Chinese cabbage and Shanghai green cabbage) > stem vegetables (lettuce) > seed and pod vegetables (broad bean) > rhizome vegetables (daikon). Vegetable species, wind direction, and local anthropogenic emissions were determinants of PAH concentrations in the edible part of the vegetable. Using isomer ratios and principal component analysis, PAHs in the vegetables were determined to be mainly from coal and wood combustion. The sources of PAHs in the six types of vegetables varied. Daily ingestion of PAHs due to dietary consumption of these vegetables ranged from 0.71 to 14.06 ng d-1 kg-1, with contributions from Chinese cabbage > broad bean > romaine > Shanghai green cabbage > lettuce > daikon. The daily intake doses adjusted by body weight in children were higher than those in teenagers and adults. Moreover, in adults, higher concentrations of PAHs were found in females than in males. For individuals of different age and gender, the incremental lifetime cancer risks (ILCRs) from consuming these six vegetables ranged from 4.47 × 10-7 to 6.39 × 10-5. Most were higher than the acceptable risk level of 1 × 10-6. Our findings demonstrate that planting vegetables near industrial facilities may pose potential cancer risks to those who consume the vegetables.

Heavy metals and lead isotopes in soils, road dust and leafy vegetables and health risks via vegetable consumption in the industrial areas of Shanghai, China.

Vegetable fields have a high risk of heavy metal contamination from pollution sources in suburban and industrial areas of cities. Eighty-seven soil samples, 106 leafy vegetables and 48 road dust samples were collected from industrial areas of Shanghai, China. We studied the levels of heavy metals, health risk through consumption of leafy vegetables, and sources of Pb in soils, road dust and leafy vegetables. Soil Cd, Zn, Pb, Cu, Hg and As concentrations exceeded the soil background values in 73.6%, 97.7%, 52.3%, 37.8%, 95.1% and 20.2% soil samples, respectively, but were below the criteria for agricultural soil in China, with the exception of Hg. The concentrations of Cd, Zn, Pb, Cu and As in road dust were significantly higher than concentrations in soils, while Hg concentration in road dust was lower. Cd, Zn, Pb, Hg and Cu concentrations in soils and Zn, Pb and Cu concentrations in road dust were greatest near the municipal solid waste incineration power plant. Heavy metal concentrations in the edible tissues of vegetables were not correlated with their total values in soils and varied among vegetable species. The trends in transfer factors (TFs) in different vegetables were Cd>Zn>Cu>As>Hg>Pb. There was low health risk from heavy metal exposure by consumption of vegetables based on Hazard Quotients (HQM): As was the major contributor to HQM, followed by Cd and Pb. Parent material of the Yangtze River Estuary was the major source of Pb in soils, while coal-fired, stationary industrial emissions and municipal waste incineration emissions were the major sources of Pb in dust and vegetables based on use of the lead isotopic tracing method. Accumulation of Pb in leafy vegetables was through foliar uptake and directly related to atmospheric Pb.

Spatial variation and sources of polycyclic aromatic hydrocarbons influenced by intensive land use in an urbanized river network of East China.

The concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs) in urbanized river networks are strongly influenced by intensive land use, industrial activities and population density. The spatial variations and their influencing factors of 16 priority PAHs were investigated in surface water, suspended particulate matter (SPM) and sediments among areas under different intensive land uses (industrial areas, agricultural areas, inner city, suburban towns and island areas) in the Shanghai river network, East China. Source apportionment was carried out using isomer ratios of PAHs and Positive Matrix Factorization (PMF). Total concentrations of 16 PAHs ranged from 105.2 to 400.5 ng/L, 108.1 to 1058.8 ng/L and 104.4 to 19,480.0 ng/g in water, SPM and sediments, respectively. The concentrations of PAHs in SPM and sediments varied significantly among areas (p < 0.05), with the highest concentrations in inner city characterized by highly intensive land use and high population density. The PAH concentrations in sediments were positively correlated with those in SPM and were more strongly correlated with black carbon than with total organic carbon, indicating a stronger influence of prolonged anthropogenic contamination than the recent surface input in sediments. Biomass and coal combustion contributed strongly to total PAHs, followed by natural gas combustion in water and SPM, and vehicular emissions in sediments. Vehicular emissions were the strongest contributors in SPM and sediments of the inner city, indicating the strong influence of vehicular transportation to PAHs pollution in the urbanized river network.

[Concentrations and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Soils and Vegetables influenced by Facility Cultivation].

The concentrations, sources, and health risks of 16 United States Environmental Protcction Agency(USEPA) priority polycyclic aromatic hydrocarbons (PAHs) in vegetables (leafy lettuce, amaranth, water spinach, and Shanghai green), in soils inside and outside the vegetable greenhouse, and in wet deposition were investigated by conducting an experiment on facility cultivation. The results showed that the average concentrations of total PAHs in vegetables and soils were 99.27 ng·g-1and 128.01 ng·g-1 in the greenhouse, and 109.11 ng·g-1 and 173.07 ng·g-1 out of the greenhouse. The concentrations of PAHs in the greenhouse were lower than those outside and the high ring-PAHs were lower than the low ring-PAHs both inside and outside. The PAH concentrations in suspended particular matter in dissolved phases of wet deposition were 2986.49 ng·g-1 and 61.9 ng·L-1, respectively. The low rings were easily enriched by the vegetables based on the shoot concentration factors. PAHs in soils and vegetables mainly originated from oil emissions and grass, wood, and coal combustion, while those in suspended particular matter in wet deposition were from petrogenic sources and the combustion of grass, wood, and coal. Petroleum combustion emissions were the main sources of PAHs in dissolved phases. We used the model of incremental lifetime cancer risks to evaluate the health risk of eating these vegetables. There was a potential risk of cancer for both children and adults for all vegetables except amaranth. The carcinogenic risk of vegetables outside the greenhouse was higher than the risk inside. Amaranth had a low carcinogenic risk with the value of incremental lifetime cancer risk lower than 10-6, while the risk of Shanghai green ranged between 10-4 and 10-6.

Characteristics, identification, and potential risk of polycyclic aromatic hydrocarbons in road dusts and agricultural soils from industrial sites in Shanghai, China.

Road dusts and agricultural soil samples were collected from eight sites close to steel mills, chemical plants, and municipal solid waste incinerator in suburban Shanghai. Sixteen polycyclic aromatic hydrocarbons (PAHs) in the United States Environmental Protection Agency (US EPA) priority controlled list were analyzed quantitatively using GC-MS. The total PAH concentrations ranged from 0.79 to 6.2 µg g-1 in road dust samples with a mean value of 2.38 µg g-1 and 0.26 to 0.54 µg g-1 in agricultural soils with an average of 0.36 µg g-1. The most abundant individual PAHs were phenanthrene, fluoranthene, pyrene, chrysene, and benzo(b)fluoranthene in dust samples and phenanthrene, fluoranthene, chrysene, and benzo(b)fluoranthene, benzo (k) fluoranthene in soil samples. Dominant compounds were four-ring and five- to six-ring PAHs, which accounted for 41.5 and 31.5 % in dusts and 33.9 and 41.1 % in soils. The spatial distribution of PAHs in dusts and soils was consistent. The wind direction could affect the spatial distribution of PAHs. Organic matter contents were found to be significantly positively correlated with PAH concentrations in both dusts and soils while grain size of particles had no correlation with PAH concentrations and could not significantly influence the distribution of PAH concentrations. PAH isomer ratios showed that combustion of grass, wood, and coal was important sources of PAHs in road dusts and agricultural soils. Toxic equivalent concentrations indicated seven kinds of carcinogenetic PAHs were major toxic equivalent concentration (TEQ) contributors, accounting for 98 % of TEQ, in the road dusts and agricultural soils. Incremental lifetime cancer risk (ILCR) estimation results showed that the PAHs in the dusts and soils had potential cancer risk for both children and adults only by direct ingestion exposure. The TEQ and ILCR values of PAHs in road dusts were much higher than those in soils, which suggested that PAHs in road dusts could be an important source of PAHs in soils.

[Spatial Distribution Characteristics and Risk Assessment of Polychlorinated Biphenyls (PCBs) in Sediments and Soils from the Dishui Lake and Its River System].

In order to investigate the pollution levels of PCBs in urban artificial lake, fourteen PCB congeners in sediments and soils of Dishui Lake and its river system were quantified by GC/MS, and then the distributions, sources and ecological risk of PCBs were discussed. The results showed that the concentrations of ∑14 PCBs in sediments and soils ranged from 0.65-16.41 ng·g-1 (dry weight, dw) and 0.47-1.27 ng·g-1, respectively, which were at a low level in general. Higher concentrations of PCBs were found in surface sediments from the river system of Dishui Lake than those in surface and core sediments from Dishui Lake, which indicated that the sediments in Dishui Lake would be polluted by the river system in the process of diversion. The concentrations of PCBs in core sediments decreased with depth, which showed that the sediments of Dishui Lake had been polluted by PCBs since its completion. In all samples, Tetra-CBs and Penta-CBs accounted for 20.65% and 67.12% of ∑14 PCBs, respectively, and PCB105, PCB118 and PCB77 were the dominant compounds. The results of source apportionment by principal component analysis (PCA) indicated that PCBs in sediments and soils from Dishui Lake and its river system were influenced by the historical cumulative emissions of 2#, 1# PCBs used in China and municipal solid waste incineration and combustion sources. The toxic equivalents (TEQs) of 12 (DL-PCBs) ranged from 0.01-79.40 pg·g-1, and the TEQs in 7 samples of surface sediments from Dishui Lake and its river system were beyond the interim sediments quality guidelines (ISQGs) suggested by USEPA, which would result in potential eco-toxicological risks for aquatic organisms.