RESUMO
The present study aimed to explore the tolerance potential of Cd, Pb and Cu and physiological alterations in two common tree species growing in Minia governorate (Egypt) namely: Eucalyptus globulus and Ficus nitida and to investigate the leaf features [leaf area (LA) and specific leaf area (SLA)] associated with the phytoremediation process. The findings may be useful for future surveillance as preliminary reference values for levels of heavy metals in urban and industrial settings. The levels of cadmium, lead and Cupper in plant leaf were determined. The results showed that heavy metals could inhibit the growth of plants including LA and SLA. The water content (WC) and photosynthetic pigments of Eucalyptus and Ficus decreased with the increased concentration of metals. Contrary to chlorophylls (a) and (b), carotenoids and chlorophyll ratio (a/b) showed a significant increase with increasing metals concentration especially that of Cd and Cu. Proline content was relatively increased and soluble carbohydrate content decreased in plants with high metal accumulation. Eucalyptus showed better tolerance capacity for Cd, Pb and Cu when compared to Ficus. The ability of Eucalyptus to accumulate and tolerate metal stress makes this species a good candidate to recuperate heavy metals-contaminated conditions.
Assuntos
Poluição do Ar , Eucalyptus , Ficus , Metais Pesados/análise , Poluentes do Solo , Biodegradação Ambiental , EgitoRESUMO
To understand the PM2.5 adsorption mechanisms of plants under different pollution levels and analyze pollutant sources, the PM2.5 adsorption amount of the leaves of two garden plant species (Cinnamomum camphora and Osmanthus fragrans) in different polluted level area (traffic area, culture and education area, cleaning area) of Changsha was measured using an aerosol generator. AFM scanning was used to obtain leaf surface micromorphological characteristics. Ion chromatography was used to measure the water-soluble ion content. Results showed that amount of PM2.5 adsorbed by leaves was positively correlated with pollution levels. The annual mean value of PM2.5adsorbed per leaf area of different plants was traffic area (0.56±0.04 µg·cm-2) > culture and education are (0.48±0.06 µg·cm-2) > clearing area (0.33±0.02 µg·cm-2). The season with amount of PM2.5adsorbed in leaves from the highest to lowest was winter (0.70±0.10 µg·cm-2) > spring (0.43±0.14 µg·cm-2) > autumn (0.39±0.12 µg·cm-2) > summer (0.31±0.09 µg·cm-2). Osmanthus fragrans had higher capacity to absorb PM2.5 than Cinnamomum camphora. Leaves of plants grown in low pollution areas were relatively smooth, whereas those in high pollution areas were rough. The order of leaf roughness in both species from high to low was traffic area (195.45±16.09 nm) > culture and education area (176.99±8.45 nm) > cleaning area (131.88±12.98 nm). The PM2.5 ionic content was the highest in winter, intermediated in spring and autumn, and the lowest in summer. The PM2.5 ions mainly included Na+, NH4+, Cl- and Br- in three pollution areas. PM2.5 pollution was due to removable source pollution at different pollution levels.
Assuntos
Poluentes Atmosféricos , Cinnamomum camphora , Adsorção , China , Monitoramento Ambiental , Material ParticuladoRESUMO
This study investigated PM2.5 adsorption by leaves of six tree species (Pinus bungeana, Pinus tabuliformis, Salix babylonica, Acer mono, Ginkgo biloba, Populus davidiana) in the West Mountain of Beijing. An aerosol generator was used for quantitative determination of PM2.5 adsorption. Atomic force microscopy (AFM) was used to determine micro morphology characteristics on the leaf surface, including roughness parameters and the PM2.5 absorption mechanism of tree leaves. The results showed that the PM2.5 adsorption capacity per unit leaf area was as follows: P. bungeana (2.44±0.22 µg·cm-2) > P. tabuliformis (2.40±0.23 µg·cm-2) > S. babylonica (1.62±0.09 µg·cm-2) > A. mono (1.23±0.01 µg·cm-2) > G. biloba (1.00±0.07 µg·cm-2) > P. davi-diana (0.97±0.03 µg·cm-2). In autumn, PM2.5 adsorption capacity per unit leaf area was as follows: November (2.33±0.43 µg·cm-2) > October (1.62±0.64 µg·cm-2) > September (1.51±0.50 µg·cm-2). The leaves of P. bungeana and P. tabuliformis were rugged with many recesses and protrusions, large relative height difference, and high roughness, and their absorption ability of PM2.5 was strong. The leaves of S. babylonica and A. mono had folded leaf lamina and were covered by fine hairs, and their roughness was relatively high, with many protrusions and fillisters on the leaf surface. Since G. biloba and P. davidiana had smooth leaves, mostly oblong stomata and low roughness, their PM2.5 absorption ability was weaker. The ranking of average roughness on the ada-xial and abaxial side of the leaves was as follows: P. bungeana (149.91±16.38 nm) > P. tabuliformis (124.47±10.52 nm) > S. babylonica (98.85±5.36 nm) > A. mono (93.74±21.75 nm) > G. biloba (80.84±0.88 nm) > P. davidiana (67.72±8.66 nm). This accorded with PM2.5 adsorption per unit leaf area, and leaf roughness had a significant positive correlation with PM2.5 adsorption amount per unit leaf area as well (R2=0.9498). To improve the environmental effects of city vegetation, tree species with leaf surface morphology that facilitates absorption of PM2.5 and other particles should be selected.