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Carolina bays are oriented, elliptical land forms of uncertain origin, present over much of the Atlantic coastal plain, and most heavily concentrated in the Carolinas. Ten Carolina bays in Horry County, South Carolina, were studied in an effort to determine their suitability for municipal effluent advanced treatment and disposal. Field studies included vegetation mapping, inventories of threatened and endangered species, substrate cores, and water quality analyses. Reported treatment efficiencies and characteristics of other natural effluent disposal sites were compared with the observed properties of the Carolina bays in order to predict effluent treatment potential and vegetational changes. The Horry County bays are typically peat-filled pocosins, however, a surprising heterogeneity in substrate depth and composition was discovered between adjacent Carolina bays. The nature of the bay substrate apparently plays a key role in determining both the water quality of overflow water from the bays, and their vegetative composition. At conservative hydraulic loading rates (between one to 5 centimeters per week of secondary effluent), the Carolina bays are predicted to provide excellent removal of biological oxygen-demanding substances, suspended solids, and total nitrogen. Some phosphorus removal in the bays is also anticipated because of the potential adsorptive capacity of the peat-based substrate.

Two artificial marsh/pond systems with a combined area of 21 ha were studied during a one-year period. Since their construction in 1978, volunteer plant colonization has resulted in a shifting mosaic of cattails (Typha spp.), water pennywort (Hydrocotlyeumbellata), frog’s-bit (Limnobiumspongia), duckweed (Lemna spp.), and other less abundant species. At least 45 bird species were observed to use the wetlands during this study with very dense populations noted for several wetland-dependent species. Alligators, fish, turtles, and snakes were abundant in the ponds. The ponds operate as flow-through systems, receiving an average treated wastewater application of 4.8 cm per week. Mass balances indicated significant percent removals for biochemical oxygen demand (82%), total suspended solids (80%), and total nitrogen (93%). Removal of total phosphorus was lower, averaging 31% over the one year study.

Twenty-four fresh marsh-wet prairie wetland sites in southwestern Florida were studied with respect to vegetation zonation, substrate characteristics, and morphometry. Six major wetland zones were identified. TheHypericum zone occupied the shallowest position (closest to the upland edge) and was confined to sandy substrates. ThePanicum-Rhynchospora zone typically followed downslope and was also associated with sandy substrates. TheMixed Emergent,Cladium,Cephalanthus andFraxinus-Salix zones all occurred on organic soils in wetland interiors. In addition to depth and substrate type, other important determinants of zone composition included fire and disturbance due to feral hog rooting and cattle grazing.