Field Measurement of Spatiotemporal Algae Distribution Using In Situ Optical Particle Size Sensor

Abstract

AbstractMany environmental problems have arisen due to algae since the large‐scale river projects were implemented in Korea. Therefore, it is imperative to monitor algal distribution status in order to find a solution to these problems. Sporadic sampling and population estimation by microscopy are traditional algae monitoring methods. However, these techniques yield spatiotemporally limited information. In order to overcome these weaknesses, the present study aimed to investigate the applicability of a new monitoring technique using an in situ optical particle sizer (LISST‐100X) for algal size and distribution estimation. The survey site was the mountain range where the Nakdong River and Nam River converge. The number of algal populations and dominant species were identified, and suspended particle concentrations and distribution were surveyed based on hydraulic characteristics, water quality, and water sampling. Field monitoring data were also collected using a unmanned aerial vehicle (UAV) in order to assess the applicability of the algal distribution estimation method using an in situ optical particle sizer for natural streams. At the time of the algae outbreak, relatively large‐sized suspended particles are distributed throughout the surface layer, which is distinguished from the similar distribution in the general water bodies. Because of these characteristics, it was possible to investigate vertical and spatial algae distribution. Additionally, the mixing pattern was analyzed according to pulsed flow in order to estimate the applicability of monitoring algal bloom removal according to discharge.