The dissolved oxygen in a pond will incrense as the sun rises at daytime,and reach the maximum quantity in the afternoon,them it will gradually go down and reach the minimum till the dawn of the next morning.

• 池塘水中的溶解氧在白天随着太阳的升起而逐渐上升，至下午达到最高值，此后溶氧量逐渐下降至第二天早晨黎明时达最低值。