Effects of Thermal Discharge from the Coastal Power Plant on the Phytoplankton in Mesocosm Experiments

In order to study the effects of power plant thermal discharge on phytoplankton in different temperature rise. Mesocosm experiment has been done in Guohua plant near the Xiangshan Bay in July 2011. The variances of the water-quality index such as Chlorophyll a, DO, COD and nutrients were analyzed. The results shown that relative to the control area M3,the Chlorophyll a in M1 (increased 0.8 degrees C) decreased by 45%, while the M2 (increased 0.4 degrees C) increased by 26%, thus, this paper comes to the conclusion that exotherm exceed 0.8 degrees C cause harm on phytoplankton growth, and exotherm that is lower than 0.4 degrees C cause little effect. The experiment found that the COD, DO and Chlorophyll a were positive correlation; nutrients and chlorophyll-a were negative correlation, these indicators can be used as auxiliary indicators in the damage assessment of the thermal discharge for phytoplankton.