The impact of seasonal change on river water quality and dissolved metals in mountainous agricultural areas and risk to human health

Abstract

Widespread land clearing for agriculture activities, urbanisation, development of hotels and residential areas has rapidly altered the land use in highland areas. These scenarios have continuously degraded the quality of river water in the area and consequently increased the risk of adverse health effects. This study investigated the impact of seasonal change on river water quality and dissolved metals in mountainous agricultural areas and the risk to human health and well-being. Water quality samples were collected from 28 sampling stations along Bertam River, Cameron Highlands, Malaysia during the wet season (September 2017) and dry season (March 2018) in which the physicochemical parameters, including temperature, conductivity, pH, turbidity, DO, salinity, TDS, and TSS were measured. The concentrations of Al, Cd, Cu, Fe, Pb, and Zn were tested via inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the overall mean concentration of all studied metals was significantly higher during the wet season compared to the dry season and the mean concentrations of dissolved metals were higher in the downstream area compared to the upstream area. Accordingly, this study confirmed that the potential sources of pollution in river water originated from agriculture activities related to landslides, land clearance, and soil erosion. The health risk for non-carcinogenic metals in adults and children was found to be within an acceptable level. However, the carcinogenic risk was significant for Cd among adults (male: 3.05 × 10−3, female: 2.97 × 10−3) and children (4.91 × 10−3).