Аннотация:Abstract An internal wave‐induced resuspension of bottom sediment and resultant changes in water chemistry were investigated in the sublittoral area of Lake Biwa in the late stage of the stagnant period. The thermocline was measured at between depths of 15 and 20 m at the beginning of the observation and rapidly dropped by 5 m within 3 h. The downward movement of the thermocline resulted in markedly increased turbidity at the top of the thermocline (20 m in water depth). Concentrations of dissolved methane synchronistically increased with turbidity, especially in the top of the thermocline where there was the highest turbidity. Total dissolved phosphorus and particulate phosphorus also increased in the thermocline. In contrast, the soluble reactive phosphate concentration decreased with time. An increase in the concentrations of particulate metals (aluminium, iron and titanium), which probably originated from mineral particles, was more marked in the water sample collected at 1 m above the bottom than at the peak of turbidity. The results indicated that an internal wave caused resuspension of the bottom sediment and also affected the water chemistry.
