Characterization and Beneficial Use of Sediment from Taylor Creek in South Florida.

Characterization and Beneficial Use of Sediment from Taylor Creek in South Florida.

Daihua Jiang, Songhe Zhang, Zhigang Li, Zhenli He, Xiaoe Yang, and Peter J Stoffella

University of Florida, IFAS, Indian River Research and Education Center, Fort Pierce, Florida 34951, USA

Sediments are often dredged from waterways to control flood and improve drainage water quality but the removal and disposal of muck sediments remain a challenge as they may contain excess salts and pollutants such as heavy metals. In this study, representative samples of sediments were collected from Taylor Creek of south Florida and analyzed for their nutritional value as soil amendment and potential contaminants with and without compost. Total C, total N, pH electrical conductivity (EC) and Na were 4.71%, 0.31%, 7.9, 7654 μS/cm and 20.3 g/kg, respectively. Cadmium (0.26 mg/kg), Cr (0.7 mg/kg), Pb (3.89 mg/kg), Co (0.96 mg/kg) and Ni (1.54 mg/kg) were detected at a low level, suggesting that environmental risk of heavy metals is minimal. With increasing proportion of sediment (0, 20, 40, 60, 80 and 100%) in the sediment-compost mixtures, which were designed to overcome salt burn to plants when used as a growth medium, pH increased while, total organic carbon, total N and plant available N decreased. The mixtures were rich in P, K, Ca and Mg and trace elements including Fe, Mn, Cu, Zn, B, and Mo while the concentrations of toxic metals such as Pb and Cd remained below critical levels. However, the high Na concentration and EC became a limit factor that inhibits plant growth. Further, a pot experiment was performed to establish optimal ratio of sediments to compost with Japanese millet as an indicator plant that were relatively tolerant to salts. The results showed that 20% sediments still resulted in poor germination of seeds (20%) while a thin layer of compost placed on the top of sediments-compost mixture (4:1) significantly improved seed germination and plant growth.

Keywords: Growth medium, heavy metals, sediment, water quality, waste management.