Abstract

The distribution and availability of copper and zinc in a constructed wetland fed with treated swine slurry from an anaerobic lagoon was studied. The methodology regarded the seasonal distribution of metals inside Schoenoplectus californicus (C.A. M,yer) Sjak, Typha angustifolia (L.), soil and liquid phase. The metals availability was measured in the soil as soluble-exchangeable, bounded to organic matter, bounded to carbonates and residual fraction. Findings shown by the liquid phase metals removal efficiency was above 90 % due to fact that metals were precipitating (over 60 %) onto the first 5 cm soil. During spring, vegetal uptake reached between 7 and 27 % (22-50 % aboveground) so that soil exchangeable fraction did not exceed 7 %. In fall, the accretion was incorporating 12 and 41 % more copper and zinc onto soil, while aboveground uptake decreased between 28 and 98 %. Bounded metals to organic matter (over 50 %) were always the dominant soil fraction. Vegetal uptake was influenced by metal availability (Zn > Cu) and plant type (Typha > Schoenoplectus).