"Lake Fukami-ike is a small eutrophic lake of 2.1 ha with a maximum depth of 7.70 m in central Japan and water stratified from March to October. Anoxic conditions prevail below 4-5 m depth from April to October and photosynthetic green sulfur bacteria (BChl.c) accumulate in the hypolimnion. A variety of civil engineering structures are constructed in water areas for the purpose of environmental protection and disaster prevention. Some heavy metal elements are included in the bioelements required for the growth of organisms. Lake Fukami-ike is a water area that has been the subject of previous studies, and the nutrients in the lake have been measured. However, the inflow, outflow and vertical distributions of bioelements in this lake and the absorption and excretion of phytoplankton are not well understood. This purpose of this study was to reveal the present state and dynamics of dissolved and particulate bioelements. The concentration of particulate trace elements in the inflow and outflow was measured, and iron was observed to have the highest mean concentration (3.46 mgL-1). The mean levels of barium, silicon, aluminum and calcium were 1.49 mgL-1, 1.07 mgL-1, 0.48 mgL-1 and 0.20 mgL-1, respectively. The maximum values of particulate calcium, magnesium, phosphorus and sulfur were observed at the depth where purple nonsulphur bacteria appeared."