Effects of plant species and diversity on methane emissions and functional gene abundances in constructed wetlands

Abstract. The sequestration of nutrients from surface waters by aquatic macrophytes and sediments provides an important service to both natural and constructed wetlands. While emergent species take up nutrients from the sediment, submerged and floating macrophytes filter nutrients directly from the surface water, which may be more efficient in constructed wetlands. It remains unclear, however, whether their efficiency is sufficient for wastewater purification and how plant species and nutrient loading affects nutrient distribution over plants, water and sediment. We therefore determined nutrient removal efficiencies of different vegetation (Azolla filiculoides, Ceratophyllum demersum and Myriophyllum spicatum) and sediment types (clay, peaty clay and peat) at three nutrient input rates, in a full factorial, outdoor mesocosm experiment. At low loading (0.43 mg P m−2 d−1), plant uptake was the main pathway (100 %) for phosphorus (P) removal, while sediments showed a net P release. A. filiculoides and M. spicatum showed the highest biomass production and could be harvested regularly for nutrient recycling, whereas C. demersum was outcompeted by spontaneously developing macrophytes and algae. Higher nutrient loading only stimulated A. filiculoides growth. At higher rates ( ≥  21.4 mg P m−2 d−1), 50–90 % of added P ended up in sediments, with peat sediments becoming more easily saturated. For nitrogen (N), 45–90 % was either taken up by the sediment or lost to the atmosphere at loadings ≥  62 mg N m−2 d−1. This shows that aquatic macrophytes can indeed function as an efficient nutrient filter but only for low loading rates (polishing) and not for high rates (purification). The outcome of this controlled study not only contributes to our understanding of nutrient dynamics in constructed wetlands but also shows the differential effects of wetland sediment types and plant species. Furthermore, the acquired knowledge may benefit the application of macrophyte harvesting to remove and recycle nutrients from both constructed wetlands and nutrient-loaded natural wetlands.

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Plant species effects on methane emissions from freshwater marshes

Atmospheric Environment ◽

10.1016/j.atmosenv.2005.02.022 ◽

2005 ◽

Vol 39 (18) ◽

pp. 3199-3207 ◽

Cited By ~ 107

Author(s):

W DING ◽

Z CAI ◽

H TSURUTA

Keyword(s):

Plant Species ◽

Methane Emissions ◽

Freshwater Marshes ◽

Species Effects

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Constructed Wetlands in Latin America and the Caribbean: A Review of Experiences during the Last Decade

Water ◽

10.3390/w12061744 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1744

Author(s):

Marco A. Rodriguez-Dominguez ◽

Dennis Konnerup ◽

Hans Brix ◽

Carlos A. Arias

Keyword(s):

Latin America ◽

Plant Species ◽

Constructed Wetlands ◽

Oxygen Demand ◽

Free Water ◽

Sufficient Information ◽

Local Conditions ◽

Latin America And Caribbean ◽

The Mean ◽

Low Performance

The review aims to report the state-of-the-art constructed wetlands (CW) in the Latin America and Caribbean (LAC) region not limited to national and local conditions. The aim is with a broader view, to bring updated and sufficient information, to facilitate the use of the CW technology in the different countries of LAC. Thus, 520 experiences extracted from the 169 reviewed documents in 20 countries were analyzed. According to the data, horizontal subsurface flow wetlands are the most reported CW in the region (62%), the second most common CW technology in the region is free water surface CW (17%), then vertical flow systems (9%), followed by intensified constructed wetlands (8%), and finally French systems (4%). The performance for nutrient removal is analyzed, finding that the mean of Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorous (TP) removal efficiencies varies from 65% to 83%, 55% to 72%, and 30% to 84%, respectively. The results suggest a generally good performance for COD and TN removal, but a low performance for TP removal. Regarding plant species used for CWs, 114 different plant species were reported, being until now the most extensive report about plant species used in CWs in the LAC region.

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