groundwater quality analysis in shahrekord aquifer

it is necessary to care the quantity and quality of the water resources especially in arid and semi-arid regions. shahrekord plain where it has a 551 km2 total area, groundwater is discharging almost 255 mcm annually and uses for drinking and agriculture. the main objective of this study was classification of groundwater quality and comparison with the drinking water standard limits in shahrekord aquifer. some of the chemical properties such as cation, anion, electrical conductivity (ec), total hardness (th) and total dissolved solids (tds) were measured in four times (spring and autumn 2004 and 2005). the results show that the some of the chemical concentration in north-western part (nwp) of the aquifer including ca, mg, so4, hco3, cl and na was lower than southern part (sp). bicarbonate in the anions and calcium in the cations has the maximum values; however they are lower than the standard limits. water type was assigned as calcium bicarbonate in terms of available ions combination in shahrekord aquifer. the th in the wells varies from 150 to 300 (mg/lit /caco3). the water quality is classified in hard water category base on th. the result shows that there wasn’t considerable difference in th and tds values on spring and autumn seasons. the maximum nitrate concentration is about of 37 mglit in agricultural landuse of northern sites. result shows that total hardness (th) and total dissolved solids (tds) in southern parts and nitrate concentration in northern parts have maximum values concentration. this subject shows that the source of these water quality parameters is difference together. azotic fertilizer seepage of agricultural lands increase nitrate contamination and urban wastewater had most effect to provide the chemical concentration and total dissolved solids.