Seasonal variation in the phytoremediation by Pontederia crassipes (Mart) Solms (water hyacinth) and its associated microbiota

• Published in: Ecological engineering Vol. 183; p. 106744
• Main Authors: de Lima, Daniel Vinícius Neves, Filho, Cesar Macedo Lima, Pacheco, Ana Beatriz Furlanetto, de Oliveira e Azevedo, Sandra Maria Feliciano
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2022
• Subjects: Macrophytes; Mesocosm; Metagenomic; Phosphorus; Rizhosphere; Phosphorus; Macrophytes; Mesocosm; Rizhosphere; Metagenomic
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2022.106744

Eutrophication is a major cause of water quality loss. It is characterized by an enrichment in the concentration of inorganic nutrients (mainly nitrogen and phosphorus) in water bodies. A promising way to mitigate eutrophication is the development of phytoremediation processes in which aquatic plants are used to assimilate nutrients from water bodies. Pontederia crassipes, also known as water hyacinth, is adapted to eutrophic environments and its high growth rate favors phytoremediation. Although this species has been widely studied for phytoremediation, few studies consider the role of the associated microbial community in this process. Our objective was to evaluate removal of nitrogen and phosphorus by P. crassipes and investigate the bacterial community associated with its roots comparing two seasons in a tropical reservoir in Brazil. A system was developed, consisting of five mesocosms of 3000 L each that simulated flow of water from input of nutrients to output of the reservoir. Each mesocosm started with 30 live plants to simulate natural mats of P crassipes. Physicochemical parameters, vegetation cover, and nutrient concentrations of the mesocosms were evaluated weekly. At the initiation and termination of the experiment (4 weeks), P and N concentrations in plant tissues were analyzed along with biomass measurements. The root associated bacterial community was analyzed by 16S rDNA sequencing. We observed that the phytoremediation process was slower in the winter than in the summer. We relate this effect to the water temperature, which decreased by an average of 7 °C. Significant differences were identified in specific bacterial orders in root-associated communities, with Chroococcales being the most abundant in the summer and Bacillales in the winter. Thus, P. crassipes can act effectively for phytoremediation throughout the year, but in colder periods, it is necessary to increase the number of plants because their growth rate is compromised. Changes in the associated bacterial community can be related to the seasonal variation in phytoremediation efficiency.