The study evaluated the performance of the species Typha domingensis Pers and Pontederia parviflora Alexander in wastewater treatment at the pilot scale. Six units of each species were built. Analyses were performed in March, June, July and November in batch system with sampling every 12 hours and a hydraulic retention time of 48 hours. Tests for performance between species and for influence of temperature were performed by analysis of variance, factorial ANOVA and principal component analysis (PCA). The evaluation of treatment performance was from physical and chemical parameters (temperature, potential of hydrogen, alkalinity, suspended solids, chemical oxygen demand) in the influent and effluent systems. The results indicated no significant difference in the performance of the species but emphasized the interference of temperature on nutrient removal capacity of both systems. The best removal efficiencies were found for volatile suspended solids (83-94 and 80-97%) and COD (38-70 and 39-74%) for T. domingensis and P. parviflora respectively, in periods of low and high temperatures.

The phytoremediation employs the use of plants and is rapidly gaining interest due to effective and inexpensive cleanup of wastewater contaminated with metals, hydrocarbons, pesticides and chlorinated solvents. This study compares the performance of the Typha domingensis and Pontederia parviflora under similar conditions, in the absorption of trivalent chrome. The determination of the absorption capacity of the species was set in four tests of survival. The aquatic macrophytes were maintained in solution of 1.5L with concentration of trivalent chromium of 70mg.L.-1 for 72 hours. At the end of the experiment the concentration of chromium in T. domingensis was 85% and 60% in P. parviflora. The concentration of Cr in P. parviflora was high in shoots and high levels of Cr were found in roots of T. domingensis indicating that the plants have difficulties to translocate Cr from the roots to shoots. Thereby, our findings indicate P. parviflora for treatment of wastewater with high concentrations of chromium and T. domingensis has its use limited in this type of treatment.

This study presents the effect of water level variation on the assemblages of herbaceous species in Mourão I Reservoir, Lago Azul State Park, Southern Brazil. The structure and distribution of populations was examined in February (dry period) and April (rainy period), 2011, in two transects. These transects started at the forest edge towards the center of the lake. The end of the transect coincided with the end of the plants within the lake. On every two meters along of the transects we sampled a wooden square of 0.25 m 2 for species biomass analysis.The macrophyte stand was composed entirely of emergent species. Considering the periods, most species were less frequent in the rainy period (April), but Ipomea ramosissima (Poir.) Choisy, Commelina nudiflora L., Eleocharis acuntagula (Roxb.) Schult. and Verbena litorales (Kunth.) had their frequency increased during this period, probably due to their resistance. The influence of flood as measured by the NMDS point out that both before and after the flood, there are plots with distinct compositions and biomass. The water level variation affects the dynamics of plant composition and structure in marginal areas of the Reservoir.Keywords: water level, herbaceous, reservoir. O efeito do nível hidrométrico sobre a vegetação herbácea de um reservatório artificial no Sul do Brasil ResumoEste estudo apresenta o efeito da variação no nível hidrométrico do reservatório Mourão I, no Parque Estadual do Lago Azul, Paraná sobre a assembleia de espécies herbáceas na região de formação do reservatório. O estudo da estrutura e distribuição das populações foi realizado nos meses de fevereiro (seca) e abril (cheia) de 2011, para isto estabeleceu-se em pontos distintos duas transecções. As transecções começavam na bordada floresta em direção ao centro do lago. O fim da coleta na transecção acontecia quando acabavam as plantas dentro do lago. Ao longo das transecções a cada dois metros um quadrado de madeira com área de 0,25 m 2 foi utilizado para amostrar as espécies, com coleta de biomassa. A maioria das espécies teve sua frequência reduzida durante a cheia (abril), porém Ipomea ramosissima (Poir.) Choisy, Commelina nudiflora L., Eleocharis acuntagula (Roxb.) Schult. e Verbena litorales (Kunth.) aumentaram sua frequência durante esse período. A influência da cheia medida pelo NMS indica que tanto antes da cheia quanto após a cheia existem parcelas com composições e biomassa típicas. A variação hidrométrica tem influência sobre a dinâmica da composição e estrutural vegetal nas áreas marginais do reservatório.Palavras-chave: nível hidrométrico, herbáceas, reservatório.