Carbon sources derived from the invasive plant Spartina alterniflora improved the nitrogen removal in seawater constructed wetland.

Invasive alien plants pose a great threat to local plants and ecosystems. How to effectively alleviate this hazard is an unresolved issue. This study explored the carbon release characteristics of an invasive plant Spartina alterniflora and evaluated the ability of nitrogen removal from shrimp culture wastewater through constructing seawater wetland. The results showed that fresh S. alterniflora had a significantly higher carbon release potential and bioavailability than that of withered S. alterniflora, and alkali-heat treatment could increase the carbon release with an average COD release rate of 33.39 mg/g from fresh S. alterniflora. The removal rate of total nitrogen was improved by about 22% in seawater constructed wetlands by adding fresh S. alterniflora biomass. Moreover, the addition of fresh S. alterniflora biomass was beneficial to the increase in the abundance of denitrification-related genera Vibrio, which might be the key to the improvement of nitrate removal efficiency in seawater constructed wetland systems. These findings indicated that invasive plants S. alterniflora as carbon sources of seawater wetland was a feasible and effective resource utilization strategy.