上覆水类型及流速对养殖池塘底泥耗氧速率的影响

为了探究上覆水类型及流速对养殖池塘底泥耗氧速率(SOD)的影响,在实验室进行6组水池平行实验,实验期为2 d,采用6个装置相同的玻璃缸进行对照实验,分别选取自来水和池塘原水作为上覆水体,在实验过程中利用水泵对上覆水进行循环流动,调节水泵循环流量以得到不同的上覆水流速,并采用2台溶氧仪测定不同实验条件下的上覆水水温和DO浓度,记录每次测量的对应时间点,测量间隔约为30 min。结果表明,当上覆水体为自来水和池塘原水时,在不同的循环流速下,SOD的范围为0.042~0.426 g/(m~2·d)。实验第2天各水池的SOD值较第1天均有一定下降,说明SOD随着水体中DO降低也相应减小,表明SOD与DO浓度有显著相关性。当上覆水处于静止状态时,其类型对SOD值有较大的影响,池塘原水在第1天和第2天的SOD值分别为0.426 g/(m~2·d)和0.297 g/(m~2·d),而自来水在第1天和第2天的SOD值均为0.258 g/(m~2·d),与上覆水体为自来水相比,有机物质含量高的池塘原水在第1天和第2天的SOD值分别高出65.12%和15.12%;当上覆水处于流动状态时,池塘原水的SOD为0.042~0.237 g/(m~2·d),自来水的SOD为0.045~0.252 g/(m~2·d),增幅仅为5.9%~15.0%,表明在此条件下上覆水体类型对实验水池的SOD值影响不显著。SOD与上覆水流速存在一定的相关性,对应最小的SOD值有一个流速较低值。

Influence of Overlying Water and Velocity on Sediment Oxygen Demand in Aquaculture Ponds

In order to understand the influence of the type and velocity of overlying water on sediment oxygen demand (SOD) in aquaculture ponds, six indoor hydrodynamic cultivation experiments were conducted under controlled conditions. The experiments were carried out in six tanks with sediment from the same aquaculture pond. Tap water and local pond water were used as the overlying water. A pump was used to regulate the water circulation rate and three water flow rates were tested for each overlying water type (0, 0.54 and 0.61 cm?s-1). The test duration was two days. The overlying water temperature, DO concentration and DO saturation under different experimental conditions were measured with a DO meter at intervals of approximately 30 minutes and the time of each measurement was recorded. The SOD ranged from 0.042 to 0.426 g/(m2?d) and decreased on the second day, corresponding with the decrease in DO and indicating that SOD is significantly affected by the DO level in the overlying water. The overlying water had a larger effect on SOD under static conditions. The SOD value with local pond water on day 1 and day 2 were 0.426 g/(m2?d) and 0.297 g/(m2?d). However, the SOD using tap water on day 1 and day 2 were both 0.258 g/(m2?d). SOD values in the pond water, with a higher content of organic matter, increased more than those in tap water, 65.12% higher on day 1and 15.12% higher on day 2.When the overlying water was flowing, the water type had no obvious effect on SOD. The SOD range was 0.042-0.237 g/(m2?d) in sediments under pond water and 0.045-0.252 g/(m2?d) under tap water, 5.9%-15% higher than with pond water. In this study, the lowest SOD occurred in static water, but the minimum SOD might occur at a flow of less than 0.54 cm?s-1. These conclusions need to be verified by further research, guided by the results of this study.