Keywords: 
• Fuyang River /
• heavy metal /
• Vibrio qinghaiensis sp. Q67 /
• Scenedesmus obliquus /
• ecotoxicity

Abstract: The water resource of Fuyang River system (FRS) has been highly exploited and seriously polluted with high levels of chemical oxygen demand and ammonia nitrogen. As a result of rapid industrialization and economic development, this area was also contaminated with heavy metals. To investigate the pollution status of heavy metals and their impact on aquatic organisms, 66 sampling sites were selected in this research based on the river structure, the hydrological conditions, the distribution of the sewage outlets and the spatial uniformity of the sampling sites. Surface sediment and water were collected. The contents of heavy metals in waters and sediments were measured using inductively coupled plasma mass spectrometry. The results indicate that the levels of heavy metals are higher than the values of National Environmental Quality Standard III for surface water in 29 water samples from all of 66 sampling sites. The contaminant are Hg, Pb, Cr, Zn. High levels of Fe and Mn exist in almost all the water samples. Water sample from southern suburbs of Handan City (sampling site 2) was seriously polluted by Fe, Zn, Cr, Hg, and Mn. The ecological toxicity of the simulative river water, based on the heavy metal levels in water sample from sampling site 2, were tested using Scenedesmus obliquus and Vibrio qinghaiensis sp. Q67 as model organisms. The results show that the EC₅₀ of the simulative river water for Vibrio qinghaiensis sp. Q67 is 6.65%, the river water is a highly toxic pollutant. The river water can’t cause the death of more than half of Scenedesmus obliquus cells at the highest concentration of heavy metals in this experiment after 4 days exposure. The SOD activity in the algal cell are generally increased first and then decreased with the increased heavy metal levels, while MDA content showed an opposite tendency, which indicate oxidative damage to algae cells during the exposure. The chlorophyll content decreased with the increasing exposure concentration, and the algae cell morphology destroyed. The MDA content is significantly increased and the chlorophyll-a content significantly decreased when heavy metal contents reach to 10% of the levels in river water. Special attention should be paid to the heavy metal pollution in FRS. The relative growth inhibition rate of Q67 and the contents of chlorophyll-a, and MDA of Scenedesmus obliquus can be used as indicators for heavy metal contamination in river water.