Recent advances in sensor technology have made high-frequency environmental data readily available. In this study, high-frequency monitoring of turbidity revealed diel turbidity cycles with peak values during the nighttime and lower values occurring during daytime. Particles responsible for these cycles were fixed suspended solids consisting mostly of aluminosilicates (clay particles) emanating from bed sediments. High-frequency data were used to investigate the transport of total suspended solids (TSS) during base flow. A majority of the base flow TSS loading occurred during the nighttime in a small agricultural catchment in Iowa, United States. Elevated nighttime turbidity coincided with an increased total suspended phosphorus loading during nighttime. Bioturbation, as a result of nocturnal feeding of fishes, is the suspected cause of the diel turbidity cycles. High-frequency monitoring was also used to detect TSS loading during storm events. Results from this study highlight the importance of high-frequency environmental measurements to reveal and understand biogeochemical transport phenomena.
Loperfido, J.V., Just, C.L., Papanicolaou, A.N., and Schnoor, J.L. (2009): In situ sensing to understand diel turbidity cycles, suspended solids, and nutrient transport in Clear Creek, Iowa. Water Resources Research 46:W06525. DOI: 10.1029/2009WR008293