Cattail population in wastewater treatment wetlands in Estonia: biomass production, retention of nutrients, and heavy metals in phytomass.

The aim of this article is to evaluate and compare common cattail (Typha latifolia) biomass production and annual accumulation of nitrogen, phosphorus, carbon, and heavy metals (Cd, Cu, Pb, Zn) in phytomass in 3 treatment wetland systems in Estonia. The biomass samples (roots/rhizomes, shoots with leaves, and spadixes) and litter were collected from 1 x 1 m plots--15 plots in Tänassilma seminatural wetland, 15 plots in Põltsamaa constructed wetland, and 10 plots in Häädemeeste constructed wetland. The highest average total cattail phytomass was 2.54 kg DW m(-2) in Häädemeeste. In Tänassilma and Põltsamaa this value was 2.3 and 2.11 kg DW m(-2), respectively. The average total aboveground biomass production and roots/rhizomes phytomass was not significantly different in three studied wetland systems. We have found significantly less spadixes and litter in Tänassilma than in Põltsamaa and Häädemeeste. In Põltsamaa, the N and P content in all plant fractions were higher than in other test areas. The Cd concentration in all samples (shoots, spadixes, litter) varied from < 0.01 to < 0.02 mg/kg. The average concentration of Zn in litter varied from 12.2 mg kg(-1) in Häädemeeste to 12.6 mg kg(-1) in Tänassilma and 13.3 mg kg(-1) in Põltsamaa. There has been found a significantly higher average contents of Cu (39.3 mg kg(-1)), Pb (30.4 mg kg(-1)), and Zn (412.3 mg kg(-1)) in Tänassilma than those in Häädemeeste or Põltsamaa: Cu-11.6 and 15.9, Pb--2.3 and 3.3, and Zn--57.5 and 73.2 mg kg(-1), respectively. The highest heavy metal retention (303.2 mg Pb m(-2), 29.4 mg Zn m(-)2, 22.9 mg Cu m(-2), and 0.35 mg Cd m(-2)) was observed in root and rhizome samples from the Tänassilma wetland.