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1. The main aim of study is to analyze Chemical Parameters such as hardness and amount of heavy metals like Pb, Hg, Fe, and As present in  water samples selected for experiment.

Water is the most abundant resource on Earth, However about 98% of the nearly 1.41 billion cubic kilometers of water in the planet is in the oceans and seas, and being salty is not suitable for drinking, irrigation and industrial uses. The fresh water available for use is only 0.003 litre out of every 100 litres of fresh water reserve. 

Water quality criteria of various groundwater has been studied from different sources e.g. Tube well, Dug well, Bore well etc. by a number of Researchers. A few of them has been listed. A literature review on heavy metal conmtamination in drinking water explores the origins, impact on health, removal techniques and regulatory measures surrounding these pollutants. Lead exposure is linked to neurological and developmental problems, specially in children. Arsenic is associated with skin lesions, cardiovascular diseases and an increased risk of cancer. Chronic exposure to Mercury causes kidney damage and reproductive issues. 

Literature review studies emphasize the importance of regular monitoring to identify potential contamination sources and prevent long-term exposure. International bodies like the World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA) have established guidelines for acceptable levels of heavy metals in drinking water. For example, the EPA's maximum contaminant level (MCL) for lead is 0.015 mg/lt, and for arsenic it is 0.01 mg/lt. Literature reviews often highlight that enforcement of these standards varies significantly worldwide. In many developing countries, regulations may not be adequately enforced due to lack of infrastructure and funding. Based on the study of different literature reviews a brief study of the water quality of Bakaliaghat, Karbi Anglong district, Assam and nearby areas is performed, in order to check the quality of water supplied.

Experimental Methods

Water Sampling Procedure

Plastic bottles of 1.0 liter capacity with stopper were used for collecting samples. Each bottle was washed with tap water and then rinsed three times with distilled water. The bottles were then preserved in a clean place. The bottles were filled leaving no air space, and then the bottle was sealed to prevent any leakage.  Each container was clearly marked with the name and date of sampling.

Water Quality Parameters

Water quality is assessed through various Chemical parameters, which are,

1. Nitrate
2. Heavy Metals (As, Fe, Hg, Pb)
3. Hardness (Ca, Mg, Total Hardness.
   

Table No. 4.1. DRINKING WATER STANDARDS (IS: 10500-2012

(Except     pH,    Colour     and    turbidity    other parameters are in mg/l)

Calcium And Calcium Hardness

To measure calcium and calcium hardness begin by preparing the water sample, ensuring it is well-mixed and filtered if needed. Add a buffer solution to the sample to maintain a stable pH, typically achieved with NaOH. Introduce murexide, a calcium indicator that changes color in the presence of calcium ions. Titrate the sample with a standardized sodium EDTA solution, which binds to the calcium ions. The endpoint of the titration is indicated by a color change of the murexide from pink to blue. Calculate the calcium hardness based on the volume of sodium EDTA used, with results expressed in milligrams per liter (mg/L) as calcium carbonate (CaCO₃). This method effectively quantifies both the concentration of calcium ions and the total hardness of the water sample.

This method provides a specific measure of calcium and calcium hardness by utilizing the selectivity of murexide and the chelating ability of EDTA in a controlled pH environment.

Calculation:

Total Hardness

The process begins with the preparation of a buffer solution, which is essential for maintaining the pH at a level where EDTA effectively binds with the calcium and magnesium ions. Typically, a pH range of 10 to 11 is maintained using ammonia or a similar buffer.

First, a water sample is treated with hydroxylamine hydrochloride, which reacts with any interfering metal ions and helps to stabilize the sample by eliminating potential interferences. Next, a small amount of Eriochrome Black T is added to the sample. EBT acts as an indicator, changing color upon binding with calcium and magnesium ions. In the presence of these ions, the solution turns red.

The actual titration process involves adding a standardized EDTA solution to the sample. EDTA, a chelating agent, reacts with the calcium and magnesium ions, forming stable complexes. As EDTA is added, the red color of the EBT complex fades, and the endpoint is reached when the solution turns blue, indicating that all the calcium and magnesium ions have reacted with the EDTA. The volume of EDTA solution used to reach this endpoint is then measured. By applying the known concentration of the EDTA solution and the volume used in the titration, the total hardness of the water can be calculated, typically expressed as mg/L of CaCO₃.

This method provides an accurate measure of total hardness by quantifying the concentration of calcium and magnesium ions through complexometric titration, using EDTA as a chelating agent and EBT as an indicator for endpoint detection.

Calculation:

 

MAGNESIUM    HARDNESS AND MAGNESIUM

With both total hardness and calcium hardness values obtained, magnesium hardness is calculated by subtracting the calcium hardness from the total hardness.

Calculation: 

Magnesium Hardness           =          Total Hardness  −   Calcium Hardness

(mg/L as CaCO₃)                               (mg/L as CaCO₃)         (mg/L as CaCO₃)

FLUORIDE

Fluoride concentration in water is measured by the SPANDS reagent method, the process involves a colorimetric analysis that provides a quantitative measurement of fluoride ions. Initially, a water sample is treated with SPANDS (Sodium Phenolphtalein Phthalein) reagent, which reacts with fluoride ions to form a colored complex. The sample is first adjusted to an appropriate pH using a buffer solution to ensure optimal conditions for the reaction.

The addition of SPANDS reagent to the sample produces a blue-colored complex in the presence of fluoride ions. The intensity of the blue color, which is directly proportional to the fluoride concentration, is measured using a spectrophotometer at a specific wavelength, typically around 570 nm. The concentration of fluoride in the sample is then determined by comparing the absorbance of the sample to a calibration curve prepared using known fluoride standards.

NITRATE NITROGEN   AND NITRATE

To estimate nitrate concentration in water, the process typically involves a colorimetric analysis using chemical reagents that form a colored complex with nitrate ions specifically using the Phenol Disulphonic Acid (PDSA) method.

The methodology involves a series of precise chemical reactions and measurements. Initially, a water sample is mixed with a known amount of KNO₃ to introduce a nitrate standard for calibration. The sample is then treated with PDSA reagent, which reacts with nitrate ions to form a yellow-colored complex. To ensure complete reaction and accurate measurement, potassium hydroxide is added to adjust the pH, and silver sulfate is introduced to remove any interfering substances by precipitating them. Following this, the sample is subjected to a color development phase, and EDTA is used to complex any residual metal ions that might interfere with the colorimetric analysis. After color development, the intensity of the yellow color is measured using a spectrophotometer at approximately 410 nm. The concentration of nitrate nitrogen and nitrate in the sample is determined by comparing the absorbance of the sample to a calibration curve prepared from standard nitrate solutions.

HEAVY METALS (As, Pb, Hg, Fe)

To measure heavy metals such as Arsenic (As), Lead (Pb), Mercury (Hg), and Iron (Fe) in water Atomic Absorption Spectroscopy (AAS) can be used, Initially, water samples are collected and pretreated to remove any particulate matter or interfering substances, often through filtration or digestion processes..

Following sample preparation, Atomic Absorption Spectroscopy is employed for the actual measurement. The process begins by introducing the prepared water sample into an atomizer, which converts the liquid sample into an aerosol. This aerosol is then aspirated into a flame or graphite furnace where it is atomized. The metal atoms in the sample absorb light at specific wavelengths corresponding to the metal of interest. For each heavy metal, a specific wavelength is selected: arsenic typically absorbs around 193.7 nm, lead around 283.3 nm, mercury around 253.7 nm, and iron around 248.3 nm.

The amount of light absorbed by the atoms is measured and compared to a calibration curve obtained from standard solutions with known concentrations of the metals. The concentration of each heavy metal in the water sample is then calculated based on the absorbance values and the calibration data. This method allows for precise detection and quantification of trace amounts of heavy metals, ensuring accurate assessment of water quality and safety.

TOTAL HARDNESS

The bar graph presents the Total Hardness measurements of various water samples collected from different locations.

Average Total Hardness of the water samples from different areas.

The analysis of total hardness across different water sources revealed notable variations. River water exhibited moderate hardness, reflecting the influence of natural mineral content and surrounding geology. Groundwater showed high hardness, attributed to its extended contact with mineral-rich geological formations. Supply water, in contrast, had low hardness due to effective treatment processes aimed at minimizing scaling and mineral buildup. Pond water demonstrated variable hardness levels, influenced by local mineral content and organic matter.

CALCIUM HARDNESS, CALCIUM CONCENTRATION

The bar graph presents the Calcium Hardness and Calcium measurements of various water samples collected from different locations.

Average Calcium Hardness of the water samples from different areas.

Fig 5.11 Average Calcium concentration of the water samples from different areas.

Calcium hardness and concentration varied across water sources: river water had moderate levels, groundwater showed high calcium hardness, supply water had low levels due to treatment, and pond water varied widely. Overall, the calcium levels in these waters are generally acceptable for drinking purposes and fall within standard data limits, though treatment and source conditions influence their suitability.

MAGNESIUM HARDNESS, MAGNESIUM CONCENTRATION

The bar graph presents the Magnesium Hardness and Magnesium measurements of various water samples collected from different locations.

Average Magnesium Hardness  of the water samples from different areas.

The magnesium hardness levels varied across the water samples. The supply water showed moderate magnesium hardness, while the river water had lower levels. Pond water exhibited moderate magnesium hardness, and the groundwater samples had the highest levels. This pattern suggests that groundwater generally has a higher concentration of magnesium compared to other sources, likely due to interactions with mineral-rich geological formations.

Average Mg Concentration of the water samples from different areas.

Magnesium levels varied across water sources: river water had moderate levels, groundwater showed high hardness, supply water had low levels due to treatment, and pond water varied. All measured magnesium levels are within acceptable drinking water standards.

FLUORIDE

Fluoride is a naturally occurring mineral found in various water sources, and its concentration in water is influenced by geological and environmental factors. In small amounts, fluoride is beneficial for dental health, helping to prevent tooth decay. However, excessive levels of fluoride in drinking water can lead to health issues such as dental fluorosis or skeletal fluorosis. Monitoring and managing fluoride concentrations in water supplies is essential to ensure safe consumption levels and protect public health.

The bar graph presents the Fluoride measurements of various water samples collected from different locations.

Average Fluoride of the water samples from different areas.

The analysis of the water samples revealed a concerning trend of elevated fluoride levels in several sources. The findings indicate significant variability in fluoride concentrations across different locations, with some areas showing levels well above the WHO's recommended limit of 1.5 mg/L. Supply water had moderate fluoride levels, which are generally safe for consumption. Elevated fluoride levels in pond and groundwater samples may pose a risk of fluorosis, a condition caused by excessive fluoride intake that can affect dental and skeletal health. The higher fluoride concentrations in certain sources indicate the need for regular monitoring and potential treatment to prevent fluorosis and ensure the safety of drinking water.

NITRATE NITROGEN

Nitrate  is a common contaminant in water, primarily originating from agricultural runoff, sewage, and industrial waste. While low levels of nitrate are typically harmless, elevated concentrations in drinking water can pose serious health risks, particularly for infants, leading to conditions such as methemoglobinemia or "blue baby syndrome."

The bar graph presents the Nitrate measurements of various water samples collected from different locations.

Average Nitrate  of the water samples from different areas.

Nitrate  levels varied across different water sources in Karbi Anglong. Supply water samples had relatively low concentrations, indicating minimal nitrate pollution. River water showed higher levels, and pond water had the highest nitrate nitrogen concentrations, suggesting potential sources of contamination. Groundwater levels were moderate but varied, indicating some local variability.

HEAVY METALS

Heavy metals in water, such as arsenic (As), lead (Pb), mercury (Hg), and iron (Fe), are significant indicators of water quality and potential health risks. Elevated levels of these metals can lead to severe health issues, including neurological, developmental, and systemic disorders.

The bar graphs below presents the As, Fe,Hg, Pb measurements of various water samples collected from different locations.

Fig 5.16 Bar Graph of As Concentration of the samples

Fig 5.17 Bar Graph of Fe Concentration of the samples

5.18 Bar Graph of  Pb Concentration of the samples

Fig 5.19 Bar Graph of Hg Concentration of the samples

The analysis of heavy metals in Karbi Anglong's water samples revealed varying concentrations of arsenic (As), lead (Pb), mercury (Hg), and iron (Fe). Water samples  exceeding critical limits of As, but not very much, indicating minimal risk of arsenic- related health issues. Lead concentrations were also within safe limits, reflecting effective control of this contaminant. However, some samples showed elevated levels of mercury, which could pose health risks if consumed over long periods. Iron levels varied, with some samples exhibiting higher concentrations, which could affect water taste and potentially cause staining. Overall, while most heavy metal levels were within acceptable limits, ongoing monitoring and management are essential to prevent any adverse health impacts from potential contaminants.

In this study, we focus on key water sources within this area to evaluate their quaity comprehensively. By examining both surface and groundwater, we aim to provide a thorough understanding of the water's condition, identify potential sources of contamination, and recommend measures to ensure the sustainability and safety of these vital resources.

The ground water and surface water of Bakaliaghat, Karbi Anglong District, Assam gives database on water quality from a variety of sources, including rivers, ring wells, tube wells etc. In this study we have tested some chemical parameters, like total hardness, calcium hardness, magnesium hardness, and concentrations of heavy metals like nitrate and  fluoride levels, From the result of experiments we get idea about concentration of various contaminants in water from different sources.

Hardness measurements showed that calcium and magnesium levels were generally within acceptable limit.

Heavy metals testing revealed that concentrations of lead (Pb), Nitrate (NO₃^-), were within safe limits, but mercury (Hg), and  (As) are little higher than WHO limit ensuring that the water will not do much harm. Similarly, nitrate and fluoride levels were analyzed and found to be within permissible limits. While the supply and groundwater generally met safety standards, To identify possible contamination and guarantee the community has clean drinking water, it is advised that regular filtration and treatment procedures  for river and pond water should be  initiated by Municipality. Overall, the study highlights how water quality varies depending on the source and offers crucial information about the chemical components of water quality.

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