Characterization of spatial and temporal variability in hydrochemistry of Johor Straits, Malaysia

• Water quality deteriorates due to reclamation work and other marine activities.
• Suspended solids show an increasing trend throughout period study.
• Copper and zinc metals present high in Johor Straits.
• Temperature, dissolved oxygen, cadmium and lead metals not significant over time change

Characterization of hydrochemistry changes in Johor Straits within 5 years of monitoring works was successfully carried out. Water quality data sets (27 stations and 19 parameters) collected in this area were interpreted subject to multivariate statistical analysis. Cluster analysis grouped all the stations into four clusters ((Dlink/Dmax) × 100 < 90) and two clusters ((Dlink/Dmax) × 100 < 80) for site and period similarities. Principal component analysis rendered six significant components (eigenvalue > 1) that explained 82.6% of the total variance of the data set. Classification matrix of discriminant analysis assigned 88.9–92.6% and 83.3–100% correctness in spatial and temporal variability, respectively. Times series analysis then confirmed that only four parameters were not significant over time change. Therefore, it is imperative that the environmental impact of reclamation and dredging works, municipal or industrial discharge, marine aquaculture and shipping activities in this area be effectively controlled and managed.