فهرست مطالب nosrat aghazadeh

The aim of this study is to investigate the hydrogeochemical characteristics of hot water springs of Khoy-Maku geothermal field, the effect of different rocks, the role of hydrothermal fluids on increasing the concentration of ions and elements in springs and estimating the reservoir equilibrium temperature. For this purpose, water samples were taken from hot and cold springs in september 2018. The results show that this water is confined and shallow and in them a water type is Na-HCO3. In springs Na and HCO3 are 736 and 2122 mg/l, respectively. Results of ion ratios, hydrogeochemical diagrams show that the high concentration of ions in the water are related to the effect of host rocks and ion exchange. Hot water springs have high Na, HCO3, and As and B are 1.47 and 0.7 mg/l, respectively. There are no evaporative rocks in the study area, therefore, the source of ions cannot be only attributed to the effect of rocks. Due to the presence of heat magmatic bodies in the depths, the high concentration of some elements, can be related to their separation from magmatic and hydrothermal systems. According Na-K-Mg diagram the thermal waters were immature waters. Therefore, the use of cation geothermometers to estimate the depth temperature of the geothermal reservoir in the region between 22 to 667 °C, can not be accurate enough. Based on silica geothermometers, mineral saturation index and enthalpy–silica mixing model, reservoir temperature was not very high and estimated in the range of 70 to 78°C.

In the aquifers of hard rock, spring water is a good indicator for evaluating the interaction of rock water and water level changes. Maku area is located in West Azarbaijan province in northwestern Iran. Supplying part of the water needed for agriculture in the region through travertine-maker springs, the role of these springs in the travertine deposition process and the effect of the chemical composition of the waters on the travertine discoloration has made the study of hydrogeochemical properties of springs in the study area important. Thus, in this research, the assessment of hydrogeochemical characteristics, chemical composition and the water origin of springs were evaluated by water sampling, sediment deposits and rock units around the springs. The results of hydrogeochemical diagrams, ionic ratios and saturation index showed that the reservoir of the aquifer is impure limestone and the water of springs is saturated to supersaturated with respect to carbonate minerals and undersaturated for sulfate minerals and chemical type mainly is Ca- HCO3. The high pressure of carbon dioxide and its removal from the water composition of the springs has caused the limestone springs of the region to have a high deposition ability and formation of Fissure-ridge and vein-type travertine with relatively high height and expansion. The results of geochemical analysis of the elements in the composition of sediments around the springs show that the correlation between CaO and Al2O3, SiO2, TiO2, Fe2O3 is negative, also the correlation between CaO and Ba and Sr is positive and also the correlation between SiO2 and Fe2O3 and Al2O3, is positive, therefore, the water source of the spring can be considered mostly thermogenic.

Due to various sources of contamination in the urban aquifers, the potential for pollution of groundwater resources is high. Thus, the vulnerability of groundwater resources can be very effective in identifying vulnerabilities and sensitive groundwater aquifers. The aim of this study was to present a modified DRASTIC Model to determine groundwater vulnerability in Urmia urban aquifer. To this end, parameters with low impact such as slope and aquifer media were ignored from the DRASTIC Model. Instead, land use, urbanization index, water value and pollution sources were added to the model. Also, the impact of unsaturated zone media and recharge layers were corrected. Results of the modified DRAST-VUL Model in the study area demonstrate that in most areas, the risk of pollution is low to moderate and the vulnerability in 29% of study area is high due to agricultural and industrial activities and low groundwater depth. Considering the results, the vulnerability index is the most sensitive measure to the parameter of pollutant sources, land use and the unsaturated zone. The sensitivity of the model to recharge, transmissivity and water value parameters were low due to the increase of impermeable surface in urban area. Based on positive results obtained from model validation through nitrate, the proposed model can be considered as an effective tool for the protection, revention and optimal utilization of groundwater resources in the study area. Also, this vulnerability model can be used for other urban aquifers.