Proposal of a Water Quality Index for Guanabara Bay (Rio De Janeiro, Brazil) with a View to Reducing Costs Related to the Environmental Monitoring

In this work, multivariate statistical methods were used to develop a specific Water Quality Index for Guanabara Bay, in order to reduce the costs related to the environmental monitoring of this estuary, without loss of information quality. The study area included fourteen monitoring stations and related data of thirteen selected parameters frequently monitored during 2010 to 2016. Factor analysis was applied to the water quality parameters to identify the relationships between them and to identify the parameters that were most significant. Consequently, the number of monitored parameters was reduced to seven (BOD, electrical conductivity, total phosphorus, total ammoniacal nitrogen, orthophosphate, turbidity and salinity), which were then considered in the Guanabara Bay Water Quality Index (WQIGB). WQIGB is an easy-to-understand index developed for Guanabara Bay that classifies water quality into three ranges (good, fair and poor), as well as provides a significant reduction of costs related to sampling and laboratory analysis.