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Heavy metals concentrations in deposited dust of typical Chinese tree species in different functional areas in Nanjing

100%

Tang J., Zha Y., Cheng Y.

Polish Journal of Environmental Studies

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2019

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tom 28

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nr 4

Foliar dust passively adsorbs anthropogenic heavy metals (HM) present in the atmosphere and thus reduces the total suspended particle (TSP) level. Urban plants have been shown to reduce the atmospheric level of ambient particulate matter (PM) via foliar dust adsorption. We studied heavy metal concentrations in the foliar dust of three typical tree species in five functional areas of Nanjing city. The highest levels of Cd (19.89±4.56 mg/kg), Pb (167.33±16.61 mg/kg) and Cr (197.42±13.96 mg/kg) were found in the Traffic Area (TA), whereas the highest levels of Cu (309.27±25.79 mg/kg) and Zn (1036.88±52.77 mg/kg) were found in the Industrial Area (IA). Significant differences were found between tree species. The amount of PM per unit leaf area generally decreased in this order: Cedrus deodara>Pittosporum tobira>Cinnamomum camphora. The highest mass percentages of large, coarse and fine PM were captured by C. camphora, P. tobira and C. deodara, respectively. A scanning electron microscope (SEM) was used to investigate the surfaces of the leaves, as well as the density and size of the stomata of each species. Our results suggest that an oily and coarse leaf surface is the most important factor facilitating PM accumulation, but large high-density stomata also enhance PM adsorption and thus favor HM accumulation in foliar dust. This study shows that the HM concentrations in foliar dust can act as an indicator of air pollution.

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PAHs in foliage dust of typical tree species with urbanization gradient in Nanjing, China

100%

Zha Y., Liu X., Tang J., Zhang Y.

Polish Journal of Environmental Studies

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2018

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tom 27

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nr 3

The foliar surface of plants can capture atmospheric pollutants. Foliage dust is especially useful for passive adsorption of anthropogenic polycyclic aromatic hydrocarbons (PAHs) present in total suspended particles (TSPs). The objective of this study was to compare the dust-retaining capability of typical trees along an urbanization gradient in Nanjing, China. We also studied the concentrations of 16 PAHs in the foliage dust of four typical tree species. We concluded that the dust-retaining capability of the four typical tree species generally decreased in the order: Firmiana simplex > Symplocos sumuntia > Photinia serrylata > Osmanthus fragrans. The highest amounts of dust per unit leaf area were captured by F. simplex, and the mean values were 84.57, 63.11, and 56.29 μg·cm-2 in urban, suburban, and rural areas, respectively. PAH concentrations in foliage dust in urban areas were significantly higher than those in suburban and rural areas. Our results suggested that grooves surrounding the stomata and the distribution of tomentum over the leaf surface were the most important factors affecting the accumulation of dust, by facilitating the capture of fine dust particles, which tend to have higher PAH concentrations than larger particles. Scanning electron microscopy (SEM) of the leaf surface of F. simplex revealed that it was covered by tomentum, with grooves surrounding the stomata, and identified this species as a potential biomonitor for atmospheric pollution. From this study, it is evident that PAH concentration of foliage dust can act as indicator of air pollution.

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Spatial-temporal variability and dust-capture capability of 8 plants in urban China

76%

Zha Y., Shi Y., Tang J., Liu X., Feng C., Zhang Y.

Polish Journal of Environmental Studies

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2019

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tom 28

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nr 1

Urban plants have been proven to mitigate ambient particulate matter (PM), which can benefit urban planners in their attempts to control urban air pollution. In this study, PM depositions on the leaves of 8 tree species were quantitatively analysed in 7 functional areas of the city of Nanjing, China, over the course of one year. The results demonstrated that leaf PM included different particle size fractions (PM₁₀ and PM₂.₅), and differed among seasons and species. The highest amounts of total PM, PM₁₀, and PM₂.₅ were found in the industrial area, and the mean values were 80.24 μg/cm², 52.14 μg/cm², and 15.51 μg/cm², respectively, and the highest accumulation of total PM (60.65 μg/cm²), PM₁₀ (37.29 μg/cm²), and PM₂.₅ (11.23 μg/cm²) occurred in winter. Significant differences were found between the tree species tested. Cedrus deodara exhibited high amounts of the total PM, PM₁₀, and PM₂.₅ accumulations. This study examined the mass and quantity distribution of PM among tree species, and identified the particles combined with a scanning electron microscope (SEM). In terms of particle mass, 48% of the identified particles had a diameter of 10 μm, and only 18.3% of them had a diameter of 2.5 μm. In terms of particle number, the results indicated that 73% of them had a diameter of 2.5 μm, and only 5.5% of them had a diameter of 10 μm. To test the relationship between leaf traits and PM₂.₅ accumulation, results showed that stomata size, density, and hair were significantly related to the PM₂.₅ capture quantity. As far as we know, this is the first paper to present the mass and quantity distribution of the PM of different tree species in Nanjing. The results not only give comprehensive insights into the dust-retaining capability of tree species but also offer a selection of species for urban green areas where the goal is to mitigate urban airborne PM.

Ograniczanie wyników

3 Polish Journal of Environmental Studies

3 Tang J.

3 Zha Y.

2 Liu X.

2 Zhang Y.

1 Cheng Y.

1 Feng C.

1 Shi Y.

2 2019

1 2018

Heavy metals concentrations in deposited dust of typical Chinese tree species in different functional areas in Nanjing

PAHs in foliage dust of typical tree species with urbanization gradient in Nanjing, China

Spatial-temporal variability and dust-capture capability of 8 plants in urban China