Phosphorus retention and fractionation in an eutrophic wetland: A one-year mesocosms experiment under fluctuating flooding conditions

Journal ar
Journal of Environmental Management
  • Volumen: 190
  • Fecha: 01 April 2017
  • Páginas: 197-207
  • ISSN: 10958630 03014797
  • Source Type: Journal
  • DOI: 10.1016/j.jenvman.2016.12.060
  • Document Type: Article
  • Publisher: Academic Press
© 2016 Elsevier Ltd This study aimed to evaluate the response of salt marshes to pulses of PO4 3--enriched water, with and without the presence of Phragmites australis. A one-year mesocosms experiment was performed in simulated soil profiles (fine-textured surface layers and sandy subsurface layers) from a coastal salt marsh of the Mar Menor lagoon under alternating flooding-drying conditions with eutrophic water, under low (1.95 mg L¿1 P-PO4 3-) and high (19.5 mg L¿1 P-PO4 3-) P load, and with the presence/absence of Phragmites. The PO4 3- concentrations in soil porewater and drainage water were regularly measured, and P accumulated in soils (including a fractionation procedure) and plants (roots, rhizomes, stems and leaves) were analyzed. The experimental mesocosms were highly effective in the removal of P from the eutrophic flooding water (>90% reduction of the P added to the system both in the soil pore water and drainage water), regardless of the nutrient load, the season of the year and the presence/absence of Phragmites. The soil was the main sink of the P added to the system, while Phragmites had a minor role in P removal. The biomass of Phragmites accumulated ~27% of the P added with the flooding water in the treatment with water of low P load while ~12% of P in that of high P load; the rhizomes were the organs that contributed the most (~67¿72% of the total P retained by the plants). Ca/Mg compounds were the main contributors to the retention of P in the soil compartment, especially in the fine-textured surface soil layers (~34¿53% of the total P in the soil was present in this fraction). Phragmites favored the retention of P onto metal oxides (~12% increase of the P retained in the metal oxides fraction in the treatment with water of high P load). Hence, the use of constructed wetlands to ameliorate the negative impacts of P-enriched waters in the Mar Menor lagoon and similar areas is recommended. We propose the incorporation of fine-textured carbonated materials, with high content of Ca/Mg compounds, and the use of Phragmites to favor the retention of P by these systems.

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