Environmental chemistry of rivers and lakes, Part VII. Fractionation by calculation of suspended particulate matter in Lake Biwa into three types of particles of different origins

During the period from July 1992 to March 1995, suspended particulate matter in Lake Biwa was collected at 1-month intervals, and the contents of Al, Si, and P were determined. Based on the analytical data, the particulate matter was fractionated by calculation into three types of particles of different origins: particles of terrigenous origin, particles of diatom origin, and particles due to microorganisms except for diatoms. The relative abundance of the respective particles was featured in water depth-time (month) diagrams, with contours in terms of weight per liter of lake water. As a result, the characteristic distributions of the particles were revealed, and their inherent roles in natural purification were distinguished from each other. Of the three types of particles, the particles of diatom origin were anticipated to be the principal scavengers not only of nutritious elements of silicon and phosphorus, but also of various metal ions dissolved in the lake. Received: October 5, 2000 / Accepted: June 6, 2001