title: Plant uptake, translocation, and return of polycyclic aromatic hydrocarbons via fine root branch orders in a subtropical forest ecosystem.
abstract: Fine roots of woody plants are a heterogeneous system differing markedly in structure and function. Nevertheless, knowledge about the plant uptake of organic pollutants via fine roots is scarce to date. In the present study, plant uptake, translocation, and return of polycyclic aromatic hydrocarbons (PAHs) via fine roots in a subtropical forest ecosystem were investigated. Levels of Σ15PAHs in different fine root branch orders of Michelia macclurei, Cryptocarya concinna, Cryptocarya chinensis, and Canthium dicoccums varied from 5072±1419 ng g(-1) to 6080±1656 ng g(-1), 4037±410 ng g(-1) to 6101±972 ng g(-1), 3308±1191 ng g(-1) to 4283±237 ng g(-1), and 3737±800 ng g(-1) to 4895±1216 ng g(-1), respectively. Overall, concentrations of low-molecular-weight PAHs with 2-3 aromatic rings were higher than high-molecular-weight PAHs with 4-6 aromatic rings in all fine root branch orders. There were obvious translocations of PAHs between adjacent branch orders and a net accumulation of PAHs may occur in the fourth- and fifth-order roots. The storage of PAHs in the fine root system showed an obvious increasing trend along the branch orders ascending for all tree species. The return flux of PAHs via fine roots mortality showed an obvious decreasing trend with the branch orders ascending across the four tree species. Lower order roots contributed greatly to the total PAHs return flux. Our results indicated that fine roots turnover is an effective pathway for perennial tree species to remove environmental toxicants absorbed into them.
authors: Shenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors: Zheng-Xia
authors: ZX
authors: Chen
authors: Shenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055, China.
authors: Hong-Gang
authors: HG
authors: Ni
authors: Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors: Xin
authors: X
authors: Jing
authors: Shenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055, China.
authors: Wen-Jing
authors: WJ
authors: Chang
authors: Shenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China. Electronic address: sunjl@pkusz.edu.cn.
authors: Jian-Lin
authors: JL
authors: Sun
authors: Shenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China. Electronic address: zenghui@pkusz.edu.cn.
authors: Hui
authors: H
authors: Zeng
mesh_terms: D017753:Ecosystem; D065928:Forests; D018517:Plant Roots / Q000378:metabolism*; D010944:Plants / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D014197:Trees / Q000378:metabolism
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons
keywords: Belowground ecology; Fine root; Plant uptake; Polycyclic aromatic hydrocarbons; Root branch order