TY - JOUR
T1 - Effect of wastewater discharge on root anatomy and radial oxygen loss (ROL) patterns of three mangrove species in Southern China
AU - Pi, N.
AU - Tam, N. F.Y.
AU - Wong, M. H.
N1 - Funding Information:
The work described in this paper was supported by the Areas of Excellence Scheme established under the University Grants Committee of the Hong Kong SAR, China (Project No. AoE/P-04/2004).
PY - 2010/7
Y1 - 2010/7
N2 - The effects of wastewater discharge on radial oxygen loss (ROL) and root anatomy varied among mangrove species. ROL of Bruguiera gymnorrhiza (L.) increased from 22.44 ng cm-2 min-1 in the control (just fresh water) to 31.09 ng cm-2 min-1 when received normal wastewater (NW) and to 44.22 ng cm-2 min-1 when treated with strong wastewater (10NW). However, discharge of both NW and 10NW caused 28% decreases of ROL in the root tip of Excoecaria agallocha L., and the decreases in Acanthus ilicifolius L. were even more significant, with 45% when treated by 10NW. The changes of ROL were related to the root anatomy. Among three species, A. ilicifolius had the highest proportional cross-sectional area of aerenchyma air spaces, suggesting that the internal oxygen transfer to root tip was the fastest. However, the area of aerenchyma air spaces in the root tip of 10NW treated A. ilicifolius was significantly reduced while area of epidermis and hypodermis (E+H) increased leading to less oxygen supply to root tip. Compared to B. gymnorrhiza and E. agallocha, the (E+H) layer of A. ilicifolius was the thinnest, and the cells without suberized walls were loosely packed in all three treatments. These results suggested that the root anatomy and ROL of B. gymnorrhiza was least affected by wastewater discharge, followed by E. agallocha, and A. ilicifolius was the most susceptible species thus was not suitable for treating strong wastewater.
AB - The effects of wastewater discharge on radial oxygen loss (ROL) and root anatomy varied among mangrove species. ROL of Bruguiera gymnorrhiza (L.) increased from 22.44 ng cm-2 min-1 in the control (just fresh water) to 31.09 ng cm-2 min-1 when received normal wastewater (NW) and to 44.22 ng cm-2 min-1 when treated with strong wastewater (10NW). However, discharge of both NW and 10NW caused 28% decreases of ROL in the root tip of Excoecaria agallocha L., and the decreases in Acanthus ilicifolius L. were even more significant, with 45% when treated by 10NW. The changes of ROL were related to the root anatomy. Among three species, A. ilicifolius had the highest proportional cross-sectional area of aerenchyma air spaces, suggesting that the internal oxygen transfer to root tip was the fastest. However, the area of aerenchyma air spaces in the root tip of 10NW treated A. ilicifolius was significantly reduced while area of epidermis and hypodermis (E+H) increased leading to less oxygen supply to root tip. Compared to B. gymnorrhiza and E. agallocha, the (E+H) layer of A. ilicifolius was the thinnest, and the cells without suberized walls were loosely packed in all three treatments. These results suggested that the root anatomy and ROL of B. gymnorrhiza was least affected by wastewater discharge, followed by E. agallocha, and A. ilicifolius was the most susceptible species thus was not suitable for treating strong wastewater.
KW - A. ilicifolius
KW - Aerenchyma
KW - B. gymnorrhiza
KW - Constructed wetland
KW - E. agallocha
KW - Epidermis and hypodermis
UR - http://www.scopus.com/inward/record.url?scp=77954265418&partnerID=8YFLogxK
U2 - 10.1080/15226510903051765
DO - 10.1080/15226510903051765
M3 - Article
C2 - 21166289
AN - SCOPUS:77954265418
SN - 1522-6514
VL - 12
SP - 468
EP - 486
JO - International Journal of Phytoremediation
JF - International Journal of Phytoremediation
IS - 5
ER -