The interacting effects of temperature and plant community type on nutrient removal in wetland microcosms

Abstract

Treatment wetlands can remove nutrients from inflow sources through biogeochemical processes. Plant composition and temperature play important roles in the nutrient removal efficiency of these wetlands, but the interactions between these variables are not well understood. We investigated the seasonal efficiency of wetland macrophytes to reduce soil leachate concentrations of total nitrogen and total phosphorus in experimental microcosms. Each microcosm contained one of six vegetation treatments: unplanted, planted with one of four species (Carex lacustris, Scirpus validus, Phalaris arundinacea and Typha latifolid) in monoculture or planted with an equal abundance of all four species. Microcosms were also subjected to two temperature treatments: insulated microcosms and microcosms exposed to environmental conditions. A constant nutrient solution containing 56 mg/l N and 31 mg/l P was added to all microcosms three times a week. Water samples were analyzed monthly for total dissolved nitrogen and total dissolved phosphorous. Microcosms exhibited a typical pattern of seasonal nutrient removal with higher removal rates in the growing season and lower rates in the winter months. In general, planted microcosms outperformed unplanted microcosms. Among the plant treatments, Carex lacustris was the least efficient. The four remaining plant treatments removed an equivalent amount of nutrients. Insulated microcosms were more efficient in the winter and early spring months. Although a seasonal pattern of nutrient removal was observed, this variation can be minimized through planting and insulation of wetlands.

Distribution patterns of plant communities and their associations with environmental soil factors on the eastern shore of Lake Taihu, China

“…Kang, Kang, and Ko (2002) found that wetland ecosystems dominated by Phragmites japonica absorbed more than 66% of the inorganic nitrogen from the soil, concluding that the study area had strong absorption ability for soil nitrogen. The demand for nutrients in wetland plants also changes with the seasons (Picard, Fraser, and Steer 2005). Previous studies also showed that wetland vegetation was the main factor influencing nutrient retention, and the biodiversity of the wetland vegetation community was significantly correlated with nutrient retention (Hammersmark et al 2009;Zhang, Yu, and Hu 2013).…”

Diagnostic préliminaire et perspectives d’élimination du phosphore (P) en excès dans le lac de Ribou (Cholet, Maine-et-Loire, France)

“…De plus, les espèces doivent montrer des capacités épuratoires importantes vis-à-vis du P. Enfin, les végétaux doivent persister au cours du temps et ne doivent pas avoir un caractère envahissant afin de ne pas bouleverser l'écosystème. Parmi les espèces autochtones répertoriées, quatre candidats s'avèrent intéressants : la Baldingère ou Faux roseau (Phalaris arundinacae) est un macrophyte efficace pour l'épuration du P (PICARD et al, 2005). Les auteurs ont montré dans des conditions expérimentales que le P dissous est éliminé jusqu'à 93 % en période estivale (juillet) et jusqu'à 63 % en période hivernale (février).…”

“…Les zones tampons aménagées pourraient représenter à terme une solution d'épuration dont l'efficacité reste à démontrer sur le site de Cholet. Toutefois, l'installation de zones humides aménagées via l'utilisation de macrophytes plantés est déjà connue surtout pour traiter les eaux usées et de nombreux auteurs y ont très fortement contribué ces dernières années (KAO et al, 2003;OBEK et HASAR, 2002;PERTTU et KOWALIK, 1997;PICARD et al, 2005;PULFORD et WATSON, 2003;SHEN et al, 2003;STEINMANN et al, 2003). Ainsi, les zones à macrophytes (plantés ou flottants) sont mises en oeuvre non seulement pour retenir les nutriments, mais aussi pour créer un environnement favorable à l'activité microbienne des biofilms (ERIKSSON, 2001;GAGNON et al, 2007).…”

Policy implications of pollution swapping

“…Removal due to vegetation may be seasonal (Picard et al, 2005) and the lowest removal rates can occur in winter and spring when most of the P enters the wetlands (Kovacic et al, 2000). As with sediments, retention of phosphorus in constructed wetlands draining catchments containing combinable crops is very variable, ranging from 1 to 91% with an average of 35% (Stevens and Quinton, in press).…”