Hydro Chemical Analysis and Suitability Determination for Irrigation for Ground Water near Solid Waste Dump Site at Pune

Over exploitation and pollution of groundwater resources is considered to one of the major pollution problems these days. Even pollution of air, surface water or land may have a signicant effect on pollution and contamination of ground water. Industries, human activities, agriculture, etc generate waste in various forms like solid, liquid and gas. If all this waste is not treated properly, it shall result polluting the environment and further affecting the quality of ground water due to its hydraulic connectivity with the hydrological cycle. In addition, leachate resulting from municipal or industrial solid waste dump site as well agricultural run-off also leads to ground water pollution. It has been estimated that around 45 million people globally are affected by water pollution resulting from excess iron, uoride, arsenic, or sea water intrusion. The current study deals with physico-chemical analysis of ground water samples and suitability determination of water by using water quality index and Piper diagram for solid waste dump site near Pune. Water samples were collected from open wells as well as bore wells for pre-monsoon and post monsoon season and results were evaluated using residual sodium carbonate, sodium hazard, sodium adsorption ratio, and piper diagram. It can be inferred that, Ca-Cl type of water predominates the study area for both pre-monsoon as well as post-monsoon season.


Introduction
Ground water is one of the major sources for drinking, agricultural and other uses. The sub-surface hydrology in uence on groundwater movement and hence contaminants migrate to the subsurface water.
The increasing rate of urbanization, agricultural activity and industrialization are mainly responsible for pollution (Sarala and Babu, 2012). Pollutants observed at a single location may be resulting from an individual source or combination of multiple sources. This study involved physico-chemical analysis of various parameters at different locations around solid waste dump site at Pune, Maharashtra, which is facing many problems related to solid waste disposal and management. Due to unscienti c solid waste disposal, large heaps of wastes are accumulated at the dumpsite. Further decomposition of this waste leads to various environmental problems like bad odour, grazing of cows, rodent and mosquito nuisance (Longe and Balogun, 2010). The leachate resulting from this dumpsite ows and percolates in the soil, resulting in groundwater pollution in nearby areas (Nilo, N. S., et al, 2013). For e cient management of ground water resources, it is necessary to do the progressive groundwater quality mapping of the entire area using GIS. The present study objective is to assess the major physicochemical parameter concentration at various samples around Pune dumpsite, identi cation of root causes of such pollutants, and determining ground water suitability for drinking or irrigation purpose using piper diagram.
Ground water quality assessment around the dump site shall help in nding the contaminants, determine water suitability for domestic or irrigation purpose and suggest treatment solution for the same. Moreover it becomes important if the groundwater resources are situated in the close vicinity of solid waste dump site (Sasane and Lohote 2013). Considering the concentration of individual and paired ions in ground water, various indices are used to determine various alkali hazards. Piper diagram is generally used to predict the hydro-geochemical facies. A piper diagram generally shows the relative concentrations of six to seven ions in a solution or water sample. The cations considered for this study are Ca, Mg, Na, and K, and the anions considered are Cl, SO 4 , HCO 3 , and CO 3 . In most of the natural waters, these cations and anions make up almost 95 to 100 percentages of the total ions present in the solution. For determining the water suitability for agriculture or irrigation purpose, Department of Agriculture for US Salinity Lab has approved various techniques like sodium hazards, Sodium absorption ratio Residual sodium carbonate.

Study Area And Sampling Locations
Pune, the seventh largest city in India by population, covering approximately 333.56 km 2 area, lies between latitudes 18 0 22' N and 18 0 35' N and longitudes 73 0 44' E and 73 0 57' E with an average altitude of 559 m above the mean sea level. The solid waste disposal site at Pune is located at Mantarwadi at Uruli Devachi in Haveli Taluka, 20 km away from Pune City between latitude 18 0 28' N and Longitude 73 0 57' E. Pune city comprises of commercial complexes, industries, hospitals, hotels, residential buildings as well as highly urban population. As a result, the solid waste generated from municipal areas is found to be heterogeneous in nature and chie y consists of papers, plastics, metals, glasses as well as  Table 1 below.

Sodium Hazards
In Irrigation waters, the amount of sodium present is generally represented in terms of per cent sodium and is calculated by the equation-1 shown below: Where, Ca +2 , Mg +2 , Na + and K + are expressed in milli equivalents per litre. The following Table 2 shows the water classi cation on the basis of Sodium percent water class for irrigation purpose. damage to the soil. The water classi cation for irrigation can be found when the SAR and speci c conductance are known. SAR is calculated using equation-2 shown below: The following Table 3 shows the water classi cation on the basis of Sodium Hazard class for irrigation purpose. The following Table-4 shows the water classi cation on the basis of Residual Sodium carbonate for irrigation purpose.

Piper Diagram
A Piper diagram comprises of two trilinear diagrams, one for anions which is shown on the lower right corner and one for cations shown on the lower left corner. For each sample, the detail from each trilinear diagram is projected up in the central quadrilateral. As a result, each sample will be plotted in the Piper diagram, one representing cations, one representing anions, and one representing the combination. As shown in gure-2 below the diamond shape is divided into various parts, where each part has signi cance, based on the cations and anions present.

Steps to be followed to plot Piper Diagram
Step 1: Convert concentrations from mg/lit to milli equivalent/lit by using following equation-4 shown below The equivalent weights of various elements are mentioned in Table 5. Step 2: Use major cations and anions concentrations-Cations -Ca, Mg, Na, and K and Anions -SO 4 , Cl, HCO 3 , and CO 3 (Alkalinity) Step Step 4: Plot percentage of each element on Cation and Anion triangle respectively.
Step 5: Project each percent on diamond diagrams.

Sodium Hazards
From the calculations, the sampling stations are checked for Sodium hazards. The results obtained are shown in gure-3.0. The percent sodium for 8 samples is between 7.26-19.46 during pre-monsoon for 8 samples and between 6.58-16.71 for 7 samples during post monsoon, which are less than 20 percent indicating excellent water quality, whereas sodium percent of 1 sample is 22.39 during pre-monsoon and that of 2 samples is between 20.46 -22.15, which falls in the standard range of 20-40 percent classifying the samples as good quality water. When the sodium range is high, Na will be absorbed by clay particles and displace Mg +2 and Ca +2 ions (Anandakumar, S., et al 2009). When Na + in water is displaced with Mg +2 and Ca +2 ions in soil, it shall reduce the soil permeability and further result in poor internal drainage of the soil. This shall restrict the movement of air and water in the soils and such soils generally become hard when dry (Saleh A., et al, 1999).

Sodium Absorption Ratio
From the calculations, the sampling stations are checked for SAR. The results obtained are shown in gure-4. SAR values fall in the range of 0.59-1.58 for pre-monsoon season for all nine samples and were found to be in the range of 0.49-1.49 during post monsoon for all the nine samples, which indicate sodium hazard class to be S1 and water quality to be excellent. Water with SAR values greater than 6, are observed to have permeability problems (Saleh A., et al, 1999).

Conclusions
The current study indicates that the solid waste disposal Urali Devachi causes various environmental and health problems in the nearby areas. Open dumping of solid waste results in bad odour, anaesthetic view as well as leachate problems during decomposition of solid waste. The leachate emanating from the dumpsite contains various contaminants like organic compounds, soluble salts and even heavy metals which combine with the ground water, polluting it. The Piper diagram helped to evaluate the hydrochemical facies in the study area, which clearly revealed the water is predominantly of Ca-Cl type for premonsoon as well as and post-monsoon season. The suitability of water for irrigation for the study area is evaluated based on SAR, Percent sodium, and RSC (Sadashivaiah, C., et al, 2008). Since all groundwater sampling stations are falling in excellent and good category for SAR and % Na, it can be concluded that all the ground water sources are safe for the irrigation use. However, all the RSC values obtained are negative, which implies that more Ca +2 and Mg +2 ions are present in the samples than carbonates ions.

Declarations
Availability of data and materials All the relevant data generated or analysed during the study is incorporated in the manuscript.   Characteristics of diamond shaped elds