Water Resources Research Act Program

Details for Project ID 2016SD261B

Controlling Harmful Algal Blooms in Eutrophic Lakes by Combined Phosphorus Precipitation and Sediment Capping (Year 2)

Institute: South Dakota
Year Established: 2016 Start Date: 2016-03-01 End Date: 2017-02-28
Total Federal Funds: $21,924 Total Non-Federal Funds: $43,951

Principal Investigators: Kyungnan Min, Guanghui Hua

Project Summary: Many lakes in South Dakota are impaired by excessive nutrients generated from non-point source pollution. The trophic status indicates that more than 80% lakes in South Dakota are characterized as eutrophic to hypereutrophic condition. Eutrophication can lead to the development of harmful algal blooms of cyanobacteria (blue-green algae), which will result in very detrimental effects on lake water quality including increased turbidity, dissolve oxygen depletion, and scum layers formation. Moreover, cyanobacteria can release potent toxins that pose significant threats to ecosystem and public health. Phosphorus (P) is considered as the growth-limiting nutrient that initiates the development of cyanobacteria. Eutrophication control has primarily focused on methods that reduce P loading in lakes, including limitation of the external P input, direct precipitation of P by coagulation, and inhibition of P release from the sediment. The external P input reduction is the prerequisite for algal bloom control. However, many studies show that the internal P loading from sediments in lakes can significantly delay lake recovery. Lake sediments are considered as sink as wells a source for P and often play a decisive role in algal blooms. Precipitation of dissolved P and algal cells by aluminum and iron salts has been used to reduce the nutrient levels and increase the water transparency to accelerate lake recovery. However, such a positive effect can be quickly diminished by the re-suspension of the algal flocs and the release of P from the sediment. The in-situ sediment capping is an emerging technology that can stabilize sediments, minimize re-suspension, and reduce P release into overlying waters using reactive P binding particles. This technology involves placement of a layer of solid-phase P sorbents (such as calcite and zeolite) to create an active barrier between the sediment and the aquatic environment. In this study, we will use laboratory batch and column experiments to evaluate the combined P precipitation and sediment capping technology to control algal blooms in South Dakota lakes. The treatment includes precipitation of dissolved and particulate P from water column and subsequent immobilization of any P released from the sediment. This technology has great potential to provide a sustainable eutrophication control strategy and accelerate the lake recovery in South Dakota and other states.