Evaluation of the concentration and distribution pattern of lead, zinc, chromium and cadmium in surface sediments of Karun River using geostatistics in GIS environment

In aquatic ecosystems heavy metals are very important due to their toxicity and endurance and having a high bio-accumulation in the environment. The aim of this research, Evaluation of the concentration and distribution pattern of heavy metals (lead, zinc, chromium and cadmium) in surface sediments of the Karun River.

To determine the concentration and distribution of heavy metals (lead, zinc, chromium and cadmium) in sediments of the Karun River in summer and winter of 2015, six stations were selected and from each station 3 samples of sediments were randomly collected. After transferring samples to the laboratory, drying and digestion of samples, the measurement of heavy metals was performed using a Flame atomic absorption spectrometry. An inverse weight-distance method was used to interpolate the distribution of heavy metals.

According to the results, zinc had the highest concentration and cadmium had the lowest concentration among the studied metals in the surface sediments of the Karun River. The mean concentrations of lead, zinc, chromium and cadmium in summer were 26.28, 72.36, 53.48 and 3.85 μg/g dry weight and in winter were 13.47, 59.59, 30.26 And 0.42 μg/g dry weight, respectively.

Comparison of the measured heavy metals concentration by the American and Canadian national guidelines indicated that levels of Cr in the summer and Cd in surface sediments were higher than the Threshold effect level (Canadian Guideline) and Lowest Effect Level (NOAA Guideline). Whereas Concentrations of other metals were lower than mentioned limits. The findings of this study provide useful information on the distribution of heavy metals concentration in the Karun River sediments which can help monitoring and assessment of sediments in the region.