Assessment of physical-chemical water quality characteristics and heavy metals content of lower johor river, Malaysia

Surface freshwater quality has received more attention in recent years, which is since fresh water is regarded as a limited resource and many threats can negatively affect the water quality. The expansion of urban pollution in the Johor River in Johor State, Malaysia, has been induced by different anthropogenic activities being carried out, which bring potential risks to freshwater quality. The aim of this study was to quantify the physical-chemical properties of water and heavy metal concentrations at 11 sampling sites (S 01-S 11) selected along the Johor River. Eight water quality parameters were determined, and nine heavy metals were determined using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Findings revealed that total suspended solid concentration and pH of the water samples satisfied the Class II outlined in the National Water Quality Standards for Malaysia (NWQSM). Most of the ammonia concentrations satisfied the Class II except at stations S 01 to S 03. The nutrient concentration (nitrate, nitrite, and phosphate) were found quite low. On the other hand, the range of certain elements such as Fe (1.75 to 6.90 ppm), Cu (0.06 to 1.34 ppm), and As (0.01 to 0.29 ppm) was found to exceed the Class II standard at all stations. A strong relationship between TSS, As, and Cu concentrations was found, which may be due to Cu and As carried along the river by suspended sediments, coming from the anthropogenic sources into the catchment areas. The results indicated that the river water quality is extremely sensitive to the local land use and practices. Further detailed research into the concentration of the elements in storm water could be the next research focus.