Assessment of Groundwater Quality for Industrial Purposes Using Geographical Information System (GIS) in Zahedan, Sistan and Baluchestan Province, Iran

1 Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. 2 Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran. 3 GIS & RS Department, Yazd Branch, Islamic Azad University, Hesabi Blv, Safaeie, Yazd, Iran. 4 Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.


Introduction
Due to environmental laws and issues related to pollution and the quality of water resources, it is necessary to pay attention to water resources quality. Population growth and water pollution, caused by urban, industrial, and agricultural wastewater discharge and leachate from landfills, have increased pollution and limited the available water resources 1 . In general, water quality in aquatic ecosystems is evaluated by physical, chemical, and biological parameters 2 . On the other hand, recognizing the contaminated sites and existing pollutants will lead to optimal and proper water use in different applications 3 . Water has various applications in different areas, such as consumption, household activities, recreation, irrigation, and industries. In this regard, certain standard values should be observed by international and national organizations with regard to water quality. Among water resourses, including the surfacewater, groundwater, snowmelt, and rainfall, groundwater is considered as one of the most widely used resources. In the case that the ionic constituents of water esceed the standard range, they can affect the living organisms' health, enter the agricultural products, and increase the costs in food maintenance and production industries 4 .
Water quality is of great importance in inductrial sections and economic development of all nations [5][6][7] . Although water quality plays a significantr role in industries, it is ignored by most authorities due to the lack of sufficient testing facilities or ignorance. Given that groundwater is considered as an important source of water supply for industries, its quality can be affected by corrosion of the metallic parts of the machinery such as plumbing systems, heat exchangers, and coil pipelines 8,9 . In industries, corrosion is mainly attributed to the quality parameters of groundwater, which consist of pH, alkalinity, TDS, dissolved oxygen (DO), total hardness (TH), EC, and temperature (T) 10 .
In this regard, Langelier saturation index (LI), Ryznar index (RI), Aggressive Index (AI), Puckorius Index (PI), and Larson-Skold Index (LS) are among the main indices applied to determine corrosion.. Many researchers applied these indices in their studies from different countries [11][12][13][14][15] . These indices are simple ones that do not have mathematical and statistical complexity and can reflect the water quality conditions. Besides geographic information system (GIS), these indices are an efficient tool for spatial processing and component interpolation [16][17][18][19][20] .
The purpose of this study is to investigate the quality of groundwater using LI, RI, AI, PI, and LS indices for industrial use. These indices were used along with spatial variation mapping applying geostatistical methods in the Zahedan City in Sistan and Baluchestan province. These data can help better understand the quality of groundwater and provide information for further studies in purification and better water quality management.

Materials and Methods
Study area and data collection Zahedan City, the capital of Sistan and Baluchestan Province in Iran, is located between longitude 60º35' to 61°22' eastern and latitude 29°07' north ( Figure 1). This area has a dry climate with dispersed observational wells. To conduct this study, 29 wells were considered in a flow zone that covers an area of about 210 km 2 . The average annual rainfall is 61.94 mm in this aquifer and the maximum and minimum temperatures are estimated as 42°C and -7.20°C, respectively 21 .
Groundwater data were collected in 2019 (winter, spring, summer, and autumn). The samples were stored in thoroughly cleaned the 2 L capacity bottles at a suitable temperature with necessary precautions for further analyses based on the APHA 22 . Parameters such as pH, EC, and TDS were measured by a Multiparameter (86505, AZ). EDTA titration was used in analyzing major ions such as magnesium (Mg 2+ ) and calcium (Ca 2+ ). A flame photometer (M410, Sherwood) was used in measuring sodium (Na + ). Sulfates

Spatial analysis and calculation of corrosion indices
Geographic Information System (GIS) maps were developed to investigate the corrosion intensity, and the corrosion indices were calculated on the average data. All spatial analyses were conducted by ArcGIS 10.6.1 software and Excel software for analyzing and charting other data. Data were normalized by the Logarithmic method and then interpolated by Inverse Distance Weighing (IDW) in the GIS environment. A detailed explanation of the calculation of indices and their interpretation is given in table 1 23 . The IDW method was used to zoning maps of the indices because IDW is simpler than Kriging 24,25 . The kriging method only works for normal distributions, while IDW can handle parameters that are not normally distributed 26 . The IDW method assumes that the unsampled points' values are more similar to the closer sampled points' values 27 .   In calculations of pH, the mentioned abbreviations and explanations are the real pHs of water; pHs show the pH in saturation state of CaCO 3 ; TDS stands for the total dissolved solids (mg/L); T representstemperature (°C), Ca 2+ is the calcium hardness of mg/L CaCO 3 ; Alk shows the alkalinity of mg/L CaCO 3 ; pH eq is the pH at equilibrium; Cl − is chloride (mg/L); SO 4 2− is sulfate (mg/L); Balk represents the bicarbonate alkalinity of mg/L CaCO 3 , and C alk is carbonate alkalinity of mg/L CaCO 3

Results
Since the water quality change is continuous, and the water quality was greatly affected by closer observation points, IDW was used in this study. The findings achieved from the groundwater quality parameters in Zahedan district are tabulated in Table 2. The pHs ranged from 6.55 to8.01. In general, most water samples were alkaline and had a good quality within the standard range of 6.5-8.5 for drinking water set by WHO 28 Issue (4), December 2020, 1162-72 Jehsd.ssu.ac.ir 1166 Based on the findings, the Langelier Index (LI) values were within the range of 0.66 -0.98 with an mean of -0.0232 (Figure 2). We also found that 55.2% of samples had LI values lower than zero that showed a corrosive nature. However, LI values of other samples (44.8%) were higher than zero. So, samples were supersaturated using scaling tendency. According to Figure 3, negative values are observed in the southwest area and just very few values are related to the northwest region of the studied region. Furthermore, most studied areas have positive LI values indiacting the scaling nature of the water samples. The negative mean values of LI show that most water samples are not saturated and have a corroding tendency.  The AI values ranged from 11.23 to 12.79, with an average of 11.94. Figure 4 shows the AI values of individual water samples in the study area. The AI values of 58.62% of the samples were within the range of 10 -12, which indicate moderate corrosiveness. In the other 17 samples, AI > 12, showing very low corrosivity. Moreover, corrosivity, in the other samples is 38% below the 11.9 and 14% in the range of 11.9 to 12, and 14% in the range of 12.1 to 12.2 is observed respectively. Also 10% of the area is allocated 12 to 12.1 and 24% for 12.2. ( Figure  5).
So, the AI values showed water in the southwest of the district, and in the region of the southeast and northwest has a scaling tendency. However, water has a scaling and non-aggressive tendency in other regions.  The Ryznar Index (RI) values were within the range of 5.89 -8.53, with a mean of 7.03. Figure 6 illustartes RI values of the groundwater samples collected from the strudy area. Based on the finidngs, 3 of 29 samples had RI values within the range of 5.5 < RI < 6.2; thus, water has a scaling tendency, 9 out of 29 samples have RI values ranging from 6.2 < RI < 6.8. Therefore, water is balanced with no scaling or corrosive tendencies. Moreover, RI values of the remaining 59% of the samples were within the range of 6.8 < RI < 8.5; in other words, the water samples had a corrosive tendency. The RI findings agreed with the index mentioned previousely and showed the same pattern ( Figure  7).   Vol (5), Issue (4), December 2020, 1162-72 Jehsd.ssu.ac.ir 1168 The general classification of Puckorius Index (PI) can be classified as PI > 7, with significant scaling tendencies. The PI varied from 7.53 to 8.68 with a meanof 8.16. All samples showed PI > 7, indicating that water samples had a considerable scaling tendency (Figure 8). The entire groundwater of this region has a significant corrosive tendency (Figure 9).

Discussion
The values of the Zahedan district's physicalchemical parameters displayed that the groundwater quality results from the effect of the nature of climate and aquifer materials and human influences. The water in the alluvium adjacent to the young flysch formation, a marine facies, has higher salt concentrations. The waters with the lowest ion concentrations are located in the coarser alluvium adjacent to the granite formation that high recharge rate occurs at valley bed alluvium of these formations 21 . Through a discharge of sewage into absorbing wells, the urban effect has caused the EC to increase in some places from about 3530 to about 12200μS/cm. In addition to the nature of the aquifer, people have had a much greater impact on groundwater quality 29 . In hard rock regions, calcium and magnesium are mainly derived from minerals like pyroxenes and amphiboles 21 . Some minerals including pyroxenes and amphiboles in the silicate rocks and dolomite and calcite are considerd as important sources of calcium and magnesium production in groundwaters. In some regions of the studied area, Na + was higher than Ca 2+ , indicating the inverse cation exchange process, in which Ca 2+ from the groundwater replaces na+ from the aquifer. However, studies of the natural origin of Na-Cl have been reported in cases such as dry sedimentation and dissolution of halite minerals. Sulfate concentration is high in location. High values of SO 4 2along with Ca 2+, suggest a possible dissolution of gypsum. The LI index, as a system of estimating and predicting the frequency of problems raised by limescale in a particular water supply, indicates the corrosiveness or incrusting ability of a water sample 30 . In other terms, this system is able to predict water tendencies to precipitate or dissolve calcium carbonate, which is considered as the main parameter in determining water corrosivity. According to this index, water's corrosive action is basically caused bythe excess of free CO 2 and its interaction with calcium and magnesium carbonates. These salts are in solution as bicarbonates in the presence of carbon dioxide. As a result, a corresponding concentration of carbon dioxide is considerd for all concentrations of calcium and magnesium in orderto prevent decomposition of these bicarbonates back into carbonates 31 . Acidic pH accelerates corrosion; in water with low alkalinity and high free carbon dioxide, the attack is more rapid than water, which has high alkalinity and low carbon dioxide contents. Consequently, we can say that pH change is required to make water in equilibrium. Generally, this index value lies between −3 and +3. A negative index shows that the water sample is under-saturated, dissolving CaCO 3, and corrosive. A value near zero indicates that the water sample is at saturation (equilibrium) and the positive value of LSI indicates that the water is over or supersaturated, that deposits CaCO 3 on the surface of metal. Therefore, the corrosion rates will be negligible 32,33 .
Aggressive index depends on the pH, total alkalinity, and calcium hardness 5 . This index is often used as an alternative method for Langeler Index and it is a parameter to determine water corrosiveness. Since temperature and TDS values are not required in this calculation, it is more userfriendly than LI. However, given that AI is less accurate than LI, it is considered a general indicator other than a quantitative measurement.
According to pH and pHs values of water, Ryznar index proved improvement over the LI 34 . It also quantified the water scaling properties in numerical values better 31 .
Alkalinity and pH of water value represent the buffering capacity and water samples' precipitation characteristics to reach equilibrium 35,36 . Puckorius index is derived from these parameters, and the equilibrium pH is used instead of the actual pH of the water. The PI uses the same numbering systems and general interpretation as does the RI 30 .
Eventually, Larson-Skold index 37 was provided according to the hydrochemical parameters, including chlorides, sulfates, carbonate alkalinity, and bicarbonate alkalinity. The water will evaporate more corrosivity in the case of a high concentration of sulfate and chloride.

Conclusion
Qualitative assessment of groundwater for industrial purposes was assessed for the Zahedan district in Sistan and Baluchestan Province, Iran. The order of dominance of cations was Na + > Ca 2+ > Mg 2+ and that of anions was SO 4 2− > Cl − > HCO 3 − . The average values of EC and TDS parameters are higher than the WHO guidelines. The corrosion and scaling indices were evaluated using five most frequently applied indexes. In this regard, using multiple indices provided more accurate information on the corrosive or scaling tendency. Spatial variation mapping of the indices indicates that the main part of groundwater in Zahedan area has a corrosion tendency. The dataset classified groundwater as unsuitable, and this indicates that the water is unreliable for industrial usage and will need further treatment.