Abstract
Low-molecular-weight organic acids (LMWOAs) represent an important component of root exudates. They play a pivotal role in the degradation of polycyclic aromatic hydrocarbons (PAHs) in sediments as they influence PAH bioavailability and degrader colonization. This study examined variations of LMWOAs in mangrove root exudates (Aegiceras corniculatum and Kandelia obovata) after exposure in phenanthrene and pyrene solution for 7 and 40 days, respectively. After 7 days of treatment, total root exudates and six types of LMWOA in root exudates from both mangrove species were enhanced. The largest increase was found in oxalic acid, i.e., the dominant component in determined LMWOAs. Coupled with the enhancement in LMWOA exudation rates, root metabolism intensities, measured as the dehydrogenase activity, increased. In contrast, after 40 days of exposure, the exudation rate of total LMWOAs had dropped markedly in PAH-contaminated groups compared to the control, indicating that PAHs negatively impacted root metabolism and activities due to their toxicity. The largest decrease was also found in oxalic acid, suggesting that the biological reactions related with oxalic acid are vulnerable under PAH stresses.
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Acknowledgements
This work was funded by the National Natural Science Foundation of China (31530008), Ministry of Science and Technology of the People’s Republic of China (2013CB956504) and National Natural Science Foundation of China (31370516). The authors would like to thank Ms. Jing Ye, Mr. Yang Bai, Dr. Jingna Du, Dr. Xiangyu Xie, Dr. Jingna Du, and Dr. Bosen Weng for the assistance in field campaigns and laboratory analyses. We also appreciate Dr. Tara Kelly at Trinity College Dublin for the grammar polishing. Thanks are also due to the anonymous reviewers and the editor, whose comments helped to improve the original manuscript.
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Jiang, S., Xie, F., Lu, H. et al. Response of low-molecular-weight organic acids in mangrove root exudates to exposure of polycyclic aromatic hydrocarbons. Environ Sci Pollut Res 24, 12484–12493 (2017). https://doi.org/10.1007/s11356-017-8845-4
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DOI: https://doi.org/10.1007/s11356-017-8845-4