TY - JOUR
T1 - The uptake of mixed PAHs and PBDEs in wastewater by mangrove plants under different tidal flushing regimes
AU - Pi, Na
AU - Wu, Yan
AU - Zhu, Hao Wen
AU - Wong, Yuk Shan
AU - Tam, Nora Fung Yee
N1 - Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017
Y1 - 2017
N2 - Wastewater often contains mixed toxic pollutants, and the contribution of plant uptake in constructed wetland treatment systems is affected by environmental conditions, particularly tidal flushing. In this study, the uptake of wastewater-borne pollutants, including a mixture of polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs) congeners, by two mangrove plant species, namely Excoecaria agallocha L. and Kandelia obovata Sheue, Liu & Yong, under different tidal flushing regimes was investigated. Results showed that Fe plaque formed on root surfaces could immobilize wastewater-borne PAHs and PBDEs. At the end of 8-month wastewater treatment, most of the pollutants removed by plants ended up in Fe plaque, with 0.12–20.83% of total PAHs and 0.78–24.76% of total PBDEs added to the microcosm retained in Fe plaque. On the contrary, the percentages of PAHs and PBDEs taken up by plant tissues were relatively small, ranging from not detected to 0.09% and from 0.01 to 2.00%, respectively. More uptake of Fe plaque-immobilized PAHs and PBDEs was found in K. obovata than in E. agallocha, leading to more plant damages in the former species due to its weaker root outer layers. While E. agallocha with stronger root protective outer layer was able to uptake more PAHs and PBDEs from wastewater but immobilize in Fe plaque than that of K. obovata. In both plant species, tidal flushing regimes significantly affected the immobilization of PAHs and PBDEs in Fe plaque, and more frequent tidal flushing led to higher percentages of immobilization. This is the first study demonstrating that E. agallocha was a more suitable mangrove plant species to remove wastewater-borne PAHs and PBDEs than K. obovata, and the significance of tidal flushing on performance of constructed mangrove wetlands.
AB - Wastewater often contains mixed toxic pollutants, and the contribution of plant uptake in constructed wetland treatment systems is affected by environmental conditions, particularly tidal flushing. In this study, the uptake of wastewater-borne pollutants, including a mixture of polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs) congeners, by two mangrove plant species, namely Excoecaria agallocha L. and Kandelia obovata Sheue, Liu & Yong, under different tidal flushing regimes was investigated. Results showed that Fe plaque formed on root surfaces could immobilize wastewater-borne PAHs and PBDEs. At the end of 8-month wastewater treatment, most of the pollutants removed by plants ended up in Fe plaque, with 0.12–20.83% of total PAHs and 0.78–24.76% of total PBDEs added to the microcosm retained in Fe plaque. On the contrary, the percentages of PAHs and PBDEs taken up by plant tissues were relatively small, ranging from not detected to 0.09% and from 0.01 to 2.00%, respectively. More uptake of Fe plaque-immobilized PAHs and PBDEs was found in K. obovata than in E. agallocha, leading to more plant damages in the former species due to its weaker root outer layers. While E. agallocha with stronger root protective outer layer was able to uptake more PAHs and PBDEs from wastewater but immobilize in Fe plaque than that of K. obovata. In both plant species, tidal flushing regimes significantly affected the immobilization of PAHs and PBDEs in Fe plaque, and more frequent tidal flushing led to higher percentages of immobilization. This is the first study demonstrating that E. agallocha was a more suitable mangrove plant species to remove wastewater-borne PAHs and PBDEs than K. obovata, and the significance of tidal flushing on performance of constructed mangrove wetlands.
KW - E. agallocha
KW - Fe plaque
KW - Immobilization
KW - K. obovata
KW - Plant uptake
UR - http://www.scopus.com/inward/record.url?scp=85026829063&partnerID=8YFLogxK
U2 - 10.1016/j.envpol.2017.07.085
DO - 10.1016/j.envpol.2017.07.085
M3 - Article
C2 - 28797899
AN - SCOPUS:85026829063
SN - 0269-7491
VL - 231
SP - 104
EP - 114
JO - Environmental Pollution
JF - Environmental Pollution
ER -