Study of Heavy Metals Pollution in Groundwater of Central Guilan Region and Mapping by Geostatistics

Groundwater resources are the most important sources to supply fresh and agriculture waters. Groundwater contaminations by pollutants cause that the groundwater quality decrease. Heavy metals are one of main environmental pollutants and the concentration of heavy metals is increasing due to agricultural and industrial activities. The objective of this study is to investigate the spatial variability of Pb، Cd، Cu and Zn concentration in the groundwater of centeral Guilan and groundwater pollution mapping in that region. Samples were taken from 50 wells of study area during the summer of 2010. Spatial variability of the data was done by GS+ v5. 1 software. First، the accuracy of Kriging (Ok) and Inverse Distance Weighting (IDW) with different powers (2، 3، 4 and 5) were evaluated by MAE and MBE indices. Then the final maps were presented. Kriging was used to prepare final map of Pb. IDW was used to prepare final map of Cu، Zn and Cd. Result showed that the concentration of Pb and Cd in groundwater of centeral Guilan region were more than the standard values for water and the concentration of Cu and Zn were less than the standard values for water. Also the results showed that spherical and exponential models gave the best result to simulate the variograms and these models can also predict the contamination of other areas.