ENVIRONMENTAL CONNECTION / THIRD QUARTER 2025 / IECA.ORG 9 the entire period was 14, 35, 77, 131 and 209, and 3.0, 7.6, 17, 29 and 46 mg m2 (10.7 feet2) respectively. Weekly grab samples were obtained 1 to 2 days before dosing and analyzed for TP, total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP), total dissolved nitrogen (TDN), total ammonia N (TAN), nitrite N (NO2-N), and nitrate N (NO3-N). Cattail height was measured weekly, and plant samples were taken after approximately three and seven weeks after the first WW dosing. There were tanks with cattails that received no WW and served as the controls. There was no pattern of response in the growth of the cattails related to the dosing, possibly because the cattail plants had undergone rapid growth in the period before dosing was initiated. The authors suggested there may have been a measurable response in the tubers, but these were not sampled. The system appears to readily absorb the added N, although some NO3-N spikes were detected, possibly coming from the soil. The P added to the cattail systems resulted in higher P in the water column initially, directly related to dose, but even at the highest dosing, the total P in the water column was <0.05 mg L1 at the end of the dosing. The 96% reduction in P concentrations occurred in spite of the relative lack of growth of the cattail plants during the dosing period. The authors suggest that this finding indicates that this type of constructed wetland can remediate WW even after the main growth period for the plants. (An example of fish production in aquaculture tanks is shown in Figure 1.) References 1. Cun D, Wang H, Jiang M, et. al. 2024. Effective Remediation of Agricultural Drainage at Three Influent Strengths by Bioaugmented Constructed Wetlands Filled with Mixture of Iron Carbon and Organic Solid Substrates: Performance and Mechanisms. Science of the Total Environment 947. doi.org/10.1016/j. scitotenv.2024.174615. 2. Blandford NC, McCorquodale-Bauer K, Grosshans R, et. al. 2024. Removal of Nutrients from Aquaculture Wastewater Using Cattail (Typha Spp.) Constructed Wetlands. J Environ Qual. 2024; 53:767-775. Doi: 10.1002/jeq2.20608. About the Expert • Rich McLaughlin, Ph.D., received a B.S. in natural resource management at Virginia Tech and studied soils and soil chemistry at Purdue University for his master’s degree and doctoral degree. He has retired after 30 years as a professor and extension specialist in the Crop and Soil Sciences Department at North Carolina State University, specializing in erosion, sediment and turbidity control. He remains involved with the Department as professor emeritus. Figure 1. Fish production in aquaculture tanks. RESEARCH BRIEFS
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