Relationship between periphyton biomarkers and trace metals with the responses to environment applying an integrated biomarker response index (IBR) in estuaries.

Estuaries are under great anthropogenic pressure. The presence of contaminants such as trace metals, organics and organometallics in the Haihe basin, Baohai Bay China indicates a deterioration of environmental quality. In this study the ecological status of three estuaries in Haihe basin was evaluated in relation to the presence of trace metals. An integrated biomarker response index (IBR) method was applied that combined biomarker responses in natural periphyton present on surface sediment with general "stress index". Sediment samples were collected at 11 sites throughout three estuaries of Haihe basin (Luanhe, Haihe and Zhangweixin) during three seasons. The IBR values indicated that the temporal variation of biological status was autumn (3.35) < spring (3.38) < summer (4.07) (The higher the value, the worse the biological status), while the spatial variation was Zhangweixin (0.73) < Luanhe (3.31) < Haihe (6.96) in spring and autumn, and Luanhe (1.79) < Zhangweixin (3.64) < Haihe (7.69) in summer. The risk quotients of trace metals in sediment samples were calculated based on the corresponding Effects Rang Low values. The temporal variation of risk quotients was autumn (10.76) < spring (11.78) < summer (15.99), while the estuarine variation was Luanhe (8.47) < Zhangweixin (12.29) < Haihe (19.42). The IBR values and risk quotients were fitted into cubic regression equations. It is proven that the good assessment of periphyton integrated biomarker responses to biological status and contaminated risk in estuarine zones.