Notice of RetractionEvaluation of Water Quality Pollution and Identification Index for the Liu River, Zhangwu County, China

The surface water quality for the Liu River within the boundaries of Zhangwu was evaluated using single factor pollution index, single factor water quality identification index and comprehensive water quality identification index. Permanganate index (CODMn), ammonium nitrogen(NH4-N), dissolved oxygen (DO), 5-days biochemical oxygen demand (BOD5), petroleum and chemical oxygen demand(COD) from 2001 to 2009 were selected for analysis. All the parameters showed temporal variations. CODMn of 2007 and COD of 2004 during low water period, BOD5 of 2006 during level period, CODMn of 2006 and BOD5 of 2005 and 2006 during high flow period were inferior to the standard for surface water (GB3838-2002, Grade IV).The comprehensive water quality were up to the standard (GB3838-2002, Grade IV). Oxygen-demanding organic matters were the main sources of the contamination, which came from agricultural non-point pollution and domestic sewage, garbage pollution and poultry and animal aqua-culture pollution. In order to improve the quality of river water environment, intensified efforts are required to prevent and control water pollution.