A study of arsenic and chromium contamination in sediments of freshwater bodies

Abstract

Arsenic (As) is generally known for its toxicity while chromium (Cr) in an appropriate amount is an essential element to man and becomes quite toxic in excessive amount. Anthropogenic activities such as industrialization, agricultural and urbanization have led to the contamination by toxic elements into aquatic environment which finally ends up in the sediment system. Environmental process such as diagenetic process causes the toxic metals to migrate from the bedrock materials into the sediment surface and finally into the water column. This process has been recognized to be the cause of arsenic contamination in well water in several countries such as Bangladesh, Taiwan, USA and Canada. Samples of freshwater sediments collected from identified rivers and lakes around Johor Bharu, in the Peninsular of Malaysia had been analyzed to determine the concentrations level of As and Cr using neutron activation analysis (NAA) technique. Certified Reference Materials (CRM) namely BCSS-1 and IAEA Soil-7 were used to provide good quality assurance control. The results obtained showed that the concentrations of As in the rivers and lakes are in the range of 10-33 µg.g-1 and 18-62 µg.g-1, respectively. The concentrations of Cr range between 25 µg.g-1 to 125 µg.g-1 and 173 µg.g-1 to 301 µg.g -1 in the river and lake sediments, respectively. The lakes sediments have higher As and Cr contents than the river sediment. The results of the As and Cr concentrations were then compared to the 'baseline value' proposed by the National Oceanic and Atmospheric Administration (NOAA), USA and interim freshwater sediment quality guidelines values established by the Canadian Sediment Quality Guidelines for The Protection of Aquatic Life.