Assessment of the Pearl River Estuary pollution by water comprehensive pollution index and biodiversity index
珠江口海域污染的水质综合污染指数和生物多样性指数评价

Two cruises were carried out to investigate the water quality and ecological status in the Pearl River Estuary in July 2006 and March 2007. Water comprehensive pollution index and biodiversity index (including phytoplankton, zooplankton and benthos) were used to assess the pollution status. In addition, rationality of the assessment by using the biodiversity index was also discussed. The results indicated that the pollution degrees of the Pearl River Estuary were between moderate to severe. Water comprehensive pollution index showed that it was at a severely polluted status both in wet and dry seasons. Biodiversity index led to different results, which varied from lightly-moderate pollution to severe pollution. Among the three biodiversity indices, we considered that zooplankton diversity index was more congruent than the other two indices in pollution status assessment. However, the evaluation criteria should be verified and modified in future study. It was concluded that assessment for the environment quality and ecological status by using different biodiversity indices may come to a varied result, and a simple conclusion could not be hastily educed but should be associated with physicochemical factors.