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Multi-scale comparison of the fine particle removal capacity of urban forests and wetlands

View Article: PubMed Central - PubMed

ABSTRACT

As fine particle (FP) pollution is harmful to humans, previous studies have focused on the mechanisms of FP removal by forests. The current study aims to compare the FP removal capacities of urban forests and wetlands on the leaf, canopy, and landscape scales. Water washing and scanning electron microscopy are used to calculate particle accumulation on leaves, and models are used to estimate vegetation collection, sedimentation, and dry deposition. Results showed that, on the leaf scale, forest species are able to accumulate more FP on their leaf surface than aquatic species in wetlands. On the canopy scale, horizontal vegetation collection is the major process involved in FP removal, and the contribution of vertical sedimentation/emission can be ignored. Coniferous tree species also showed stronger FP collection ability than broadleaf species. In the landscape scale, deposition on the forest occurs to a greater extent than that on wetlands, and dry deposition is the major process of FP removal on rain-free days. In conclusion, when planning an urban green system, planting an urban forest should be the first option for FP mitigation.

No MeSH data available.


Accumulation of FP of plants: PA: P. australis, SV: S. validus, LW: I. wilsonii, TO: T. orientalis, IS: I. setosa, LS: L. salicaria, MA: M. alba, SM: S. matsudana, QV: Q. variabilis, PC: P. Canadensis, SJ: S. japonica, GS: G. sinensis, SC: S. chinensis.
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f3: Accumulation of FP of plants: PA: P. australis, SV: S. validus, LW: I. wilsonii, TO: T. orientalis, IS: I. setosa, LS: L. salicaria, MA: M. alba, SM: S. matsudana, QV: Q. variabilis, PC: P. Canadensis, SJ: S. japonica, GS: G. sinensis, SC: S. chinensis.

Mentions: Figure 3 describes the FP accumulation of each species on the surfaces and wax layers of leaves. The mean FP amounts of trees are higher than those of aquatic plants, but differences observed are not significant (P = 0.061). FP accumulation on tree species ranged from 3.85 μg cm −2 to 9.78 μg cm −2, with an average value of 5.91 μg cm −2, while that on aquatic plants ranged from 1.23 to 5.98 μg cm −2, with an average value of 3.03 μg cm −2. Among the aquatic plants, I. wilsonii presents the highest mean accumulation (5.98 ± 3.24 μg cm −2), followed by P. australis (4.78 ± 0.93 μg cm −2); by contrast, T. orientalis, I. setosa, and L. salicaria show considerably lower accumulation values (less than 1.90 μg cm −2). Among tree species, Q. variabilis (9.79 ± 1.82 μg cm −2) and S. matsudana (8.90 ± 1.39 μg cm −2) present higher FP accumulations; the accumulations of M. alba, S. japonica, and G. sinensis are relatively lower (less than 4.0 μg cm −2). While differences in accumulation on leaf surfaces between aquatic plants and trees are not significant (P = 0.176), those on wax layers are significant (P = 0.003); specifically, accumulation on the waxy layer of trees is higher than that on the waxy layers of aquatic plants. FP amounts accumulated on the leaf surface are much higher than those observed on the wax layer (P = 0.003). While differences in accumulation between the leaf surface and waxy layer of aquatic plants are fairly obvious, those for tree species such as S. japonica are relatively low.


Multi-scale comparison of the fine particle removal capacity of urban forests and wetlands
Accumulation of FP of plants: PA: P. australis, SV: S. validus, LW: I. wilsonii, TO: T. orientalis, IS: I. setosa, LS: L. salicaria, MA: M. alba, SM: S. matsudana, QV: Q. variabilis, PC: P. Canadensis, SJ: S. japonica, GS: G. sinensis, SC: S. chinensis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5385566&req=5

f3: Accumulation of FP of plants: PA: P. australis, SV: S. validus, LW: I. wilsonii, TO: T. orientalis, IS: I. setosa, LS: L. salicaria, MA: M. alba, SM: S. matsudana, QV: Q. variabilis, PC: P. Canadensis, SJ: S. japonica, GS: G. sinensis, SC: S. chinensis.
Mentions: Figure 3 describes the FP accumulation of each species on the surfaces and wax layers of leaves. The mean FP amounts of trees are higher than those of aquatic plants, but differences observed are not significant (P = 0.061). FP accumulation on tree species ranged from 3.85 μg cm −2 to 9.78 μg cm −2, with an average value of 5.91 μg cm −2, while that on aquatic plants ranged from 1.23 to 5.98 μg cm −2, with an average value of 3.03 μg cm −2. Among the aquatic plants, I. wilsonii presents the highest mean accumulation (5.98 ± 3.24 μg cm −2), followed by P. australis (4.78 ± 0.93 μg cm −2); by contrast, T. orientalis, I. setosa, and L. salicaria show considerably lower accumulation values (less than 1.90 μg cm −2). Among tree species, Q. variabilis (9.79 ± 1.82 μg cm −2) and S. matsudana (8.90 ± 1.39 μg cm −2) present higher FP accumulations; the accumulations of M. alba, S. japonica, and G. sinensis are relatively lower (less than 4.0 μg cm −2). While differences in accumulation on leaf surfaces between aquatic plants and trees are not significant (P = 0.176), those on wax layers are significant (P = 0.003); specifically, accumulation on the waxy layer of trees is higher than that on the waxy layers of aquatic plants. FP amounts accumulated on the leaf surface are much higher than those observed on the wax layer (P = 0.003). While differences in accumulation between the leaf surface and waxy layer of aquatic plants are fairly obvious, those for tree species such as S. japonica are relatively low.

View Article: PubMed Central - PubMed

ABSTRACT

As fine particle (FP) pollution is harmful to humans, previous studies have focused on the mechanisms of FP removal by forests. The current study aims to compare the FP removal capacities of urban forests and wetlands on the leaf, canopy, and landscape scales. Water washing and scanning electron microscopy are used to calculate particle accumulation on leaves, and models are used to estimate vegetation collection, sedimentation, and dry deposition. Results showed that, on the leaf scale, forest species are able to accumulate more FP on their leaf surface than aquatic species in wetlands. On the canopy scale, horizontal vegetation collection is the major process involved in FP removal, and the contribution of vertical sedimentation/emission can be ignored. Coniferous tree species also showed stronger FP collection ability than broadleaf species. In the landscape scale, deposition on the forest occurs to a greater extent than that on wetlands, and dry deposition is the major process of FP removal on rain-free days. In conclusion, when planning an urban green system, planting an urban forest should be the first option for FP mitigation.

No MeSH data available.