Influence of polycyclic aromatic hydrocarbons on nitrate reduction capability in mangrove sediments
Shan Jiang1, Yan Su1, Haoliang Lu1
1Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, 361005, China.
Abstract:
In the present study, we investigated the influence of phenanthrene (PHE), a three-ring polycyclic aromatic hydrocarbon (PAH) compound, on nitrate (NO3-) reduction processes in mangrove sediments using microcosms. After 10days, nitrate/nitrite reductase activity and abundance of narG and nirS significantly decreased in the bulk sediment at both 10/50mgPHEkg-1 contamination groups. In the rhizosphere, abundance of narG, nirS and nirK markedly declined at PHE treated sediments, while the drop in reductase activity at 10mgkg-1 PHE treatment was insignificant. After 50days, apart from 10mgPhekg-1 treated bulk sediment, abundance of denitrifiers and reductase activity in all PHE spiked sediment samples significantly dropped. Therefore, the influence of PAHs on NO3- reduction capability in mangrove sediments is dependent on spiked concentration, temporal scale of exposure and interaction with roots. Generally, PAHs play an inhibitor role, slowing NO3- turnover rates, which warrant attention from coastal managers.
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