Muscle Shoals, Alabama 35660, USA Growth and biomass accumualtion of selected nutrients and trace metals were monitored for six species of aquatic macrophytes during June, August and November, 1993. Plant species were cultivated in two polyculture treatments, each replicated three times. Polyculture I consisted of Scirpus acutus (hardstem bullrush), Phragmites communis (common reed), and PhaZaris mmiinaceu (canary grass). Polyculture II consisted of Trpha spp. (cattail), Scirpus atrovirens (green bullrush), and Scirpus cyperims (wool grass).Each of the six cells ( 6 x 9 x 0.6 m), was operated as a gravel-substrate, subsurface-flow wetlands in a continuous recirculating mode. At six week intervals, macro, micro and trace elements were dissolved and added to the sump of the recirculating system . On each of three sampling dates, replicate shoot and root samples were collected, segregated by species and tissue type (roots, rhizomes, stems and leaves), and prepared for gravimetric biomass estimates and chemical analysis. Tissue specific concentrations of N, P, K, Ca, Mg, Fe, Mn, Zn and Cu. were determined on each date for each species and tissue type. Results will be discussed with respect to species specific growth rates, biomass accumulation, and seasonal uptake and translocation of plant nutrients. KEYWORDSAquatic macrophytes; biomass; constructed wetlands; heavy metals; mesocosm; nutrients; root to shoot rat io; translocation; NTRODUCTION Emergent aquatic plants help to regulate water quality and concentrations of nutrients and other dissolved compounds in natural and constructed wetlands.Nutrient regulation is via plant uptake, biomass accumulation and modification of the rhizosphere to facilitate microbially mediated oxidation-reduction reactions , Brix 1993, Armstrong et ai. 1990, and Gersberg et al. 1986). Although uptake and storage of nutrients by aquatic macrophytes is relatively minor compared to storage and retention in wetland soils (Johnston 1991), their ability to assimilate and transform dissolved nutrients and other substances into stable organic compounds can result in significant improvements in the quality of surface waters. According to Reddy and DeBusk (1987), desirable traits of emergent macrophytes for waste water treatment include rapid growth, high biomass potential and the ability to assimilate and store nutrients for prolonged periods of time. Extensive data bases have been compiled which provide information related to rates of nutrient uptake, tissue specific nutrient concentrations and nutrient storage capacity for many of the floating and emergent macrophytes (Johnson 1991, Reddy andDebusk 1985). However, much of the information is derived from surface flow and natural wetland studies conducted at different locations, during different seasons and under widely differing environmental condition. In a recent technology assessment of subsurface flow constructed wetlands it was noted that there is a critical need for evaluating wetland plants other than cattails reeds and rushes (Reed 1993

Abstract. A microcosm study was conducted to evaluate the use of anaerobic wetlands preceding aerobic wetlands for removal of Mn, Cu, Ni, Zn, and Pb in wastewater.Initial concentrations for Mn, Cu, Ni, Pb, and Zn were 20, 2.0, 1.5, 2.1, and 2.0 mg/L, respectively. Each experimental unit consisted of three cattlefeeding troughs (cells) set in series.The first cell was anaerobic and the last two were aerobic.Water was delivered to the wetland cells at 20 mL/min for a period of 380 days starting August 24, 1994.The anaerobic wetlands consisted of three treatments replicated two times.The aerobic wetlands consisted of two treatments replicated three times. One anaerobic treatment contained organic matter and limestone (SP).Another anaerobic treatment contained organic matter, limestone, and canarygrass (SP&CG).The third anaerobic treatment consisted of canarygrass planted in river gravel (RG).Water flowed into the top and was discharged from the bottom of each anaerobic wetland. The aerobic