Floating treatment wetlands (FTWs) are a relatively new water treatment practice that consists of emergent wetland plants planted on floating mats constructed of buoyant material. This study utilized batch-fed mesocosms, with a seven-day retention time, to investigate the total nitrogen (TN) and phosphorus (TP) remediation capability of two commercially available FTW technologies using runoff from a combined irrigation holding and stormwater retention pond. Nutrients in the pond water are attributed to runoff from nearby fertilized research plots upgradient. The FTW technologies included Beemats (Beemats LLC, New Smyrna Beach, FL, USA) and BioHaven 1 floating islands (Floating Island International, Inc. Shepard, MT, USA) planted with Juncus effusus (soft rush). Due to an increase in TN and TP in the initial phase of the experiment during the plant establishment phase (weeks 1-8), BioHaven 1 nutrient removal was lower over the entire experimental period than the Beemat treatment. Differences between the two treatments, such as mat material or substrate materials and/or additives may account for this difference. The BioHaven 1 FTW removed 25% and 4%, while the Beemat removed 40% and 48% of the TN and TP, respectively expressed in terms of net removal over the entire study. During the plant growth season (weeks 9-18 of the study), the two technologies showed similar nutrient removal rates: for TN:0.026 AE 0.0032 and 0.025 AE 0.0018, and for TP:0.0074 AE 0.00049 and 0.0076 AE 0.00065 g/m 2 /day for Beemat and Biohaven 1 , respectively. A control treatment, meant to reflect nutrient removal within the pond without the presence of plants, yielded 28% and 31% removal of TN and TP, respectively. Thus, the Beemat mat yielded a significant positive net removal of TN and TP. The BioHaven 1 biomass was significantly greater than the Beemat treatment. Both treatments showed greater biomass accumulation in shoots rather than in roots. Plant nutrient content was similar between the two treatments.

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The phytoremediation potential of water hyacinth, Eichhornia crassipes (Mart.) Solms, was examined in two independent studies under nitrogen (N) rates of 0, 40, 80, 100, 150, 200, and 300 ppm. A modified Hoagland solution was added to ponds containing water hyacinths which were rated and measured weekly for 4 weeks. The hyacinths accounted for 60-85% of the N removed from solution. Net productivity, as measured by dry matter gain, increased with an increase in N rate until 80 ppm. Above that level dry matter productivity was similar. Tissue N increased linearly with dry matter gain, but total nitrogen removal from the water increased exponentially with net dry matter gain or with an increase in canopy cover. The relation between total N in plant tissue and N removal from the water was similar for the two experiments.

Treated effluent from the Hampton Roads Sanitation District (HRSD) Virginia Initiative Plant (VIP) was evaluated in 2000 and 2001 as an irrigation source for landscape plants. Landscape plants common to eastern Virginia were installed in raised beds and overhead irrigated at the rate of 2.5 cm (1 in) per week for five months. Aesthetic quality ratings, and soil and water analyses, were conducted monthly. Aesthetic quality ratings were lower on certain plants irrigated with treated effluent in both years of the study. Damage appeared to result from foliar contact by irrigation water high in dissolved salts. Soil tests showed salt accumulation in the planting soil. Damage that occurred on plants irrigated with treated effluent was species specific and included leaf burn, chlorosis, defoliation, stunting, and death. All symptoms were consistent with and typical of salt damage. Salt concentrations in this treated effluent were too high to allow use of this water as an overhead irrigation source for many landscape plants without further treatment or dilution. Irrigation with treated effluent should be based on landscape species composition, local climate conditions, and irrigation method.

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Considered overall, the results of our review suggest that the face of pain research published in PM has changed considerably in the past 60 years. Given the ongoing commitment of psychosomatic researchers to this area, we expect this evolution to continue in the years to come.

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