Effects of floods on nutrient and metal concentrations in a coastal plain stream

• Published in: Water resources research 1981-06, Vol.17 (3), p.758-764
• Main Authors: Mulholland, P.J, Yarbro, L.A, Sniffen, R.P, Kuenzler, E.J
• Format: Article
• Language: English
• Subjects: Freshwater
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/WR017i003p00758

Water quality in Creeping Swamp, a coastal plain stream in North Carolina, was monitored during two floods in 1976. The concentrations of most of the filterable substances studied remained relatively constant, particularly at the upstream station, CP‐20, which drained the least disturbed portion of the watershed. Concentrations of NO3 and dissolved organic carbon increased, and concentrations of Cl decreased during the floods at CP‐20. At the downstream station, CP‐10, which received effluents from a hog farm, concentrations of the filterable forms of N, P, K, and Fe increased markedly during floods. Indications were that increases in concentration of filterable substances during floods may be a better indicator of watershed disturbance than ambient concentrations. Despite the dominance of overland flow in the hydrologic regime and the abundance of organic material in the stream channel and floodplain, concentration patterns of the filterable constituents of streamflow during floods in Creeping Swamp are similar to the patterns in streams draining upland watersheds, where contact between runoff waters and the inorganic strata of watershed soils is likely to be much greater. The concentrations of particulate forms of phosphorus, silicon, and most of the metals studied increased during the rising limb of the hydrograph, peaked prior to peak streamflow, and decreased thereafter. The contribution of floods to total annual flux of P, Fe, Si, and Al in Creeping Swamp is especially great because of large increases in concentrations of the particulate forms of these elements as streamflow increases.