Modeling censored data for a holistic assessment of heavy metal contamination in Cartagena Bay, Colombian Caribbean

The Bay of Cartagena, located in the Colombian Caribbean, suffers from significant pollution caused by urban, industrial, commercial, tourism, maritime, and port activities. Studies conducted since the 1970s have documented contamination by heavy metals such as Cu, Cr, Ni, and Zn, which are essential for living organisms due to their role in metabolic functions, but at excessive concentrations, they become toxic. From 2015 to 2019, within the framework of REDCAM, the metals Cr, Cd, Pb, Cu, Ni, and Zn were monitored in the Bay of Cartagena, finding that only 25% of the collected data were at quantifiable concentrations and the remaining 75% were below the laboratory's quantification limits, which has hindered the determination of whether the contaminants are present or absent, leading to the reporting of censored data. This study aimed to propose an alternative analysis for these censored data using the regression on order statistics (ROS) model and to perform a temporal comparison of heavy metal concentrations in the Bay of Cartagena, thereby providing a more accurate assessment of its metal contamination status.