Abstract

A rapid assessment of drinking water quality in the Assam-Nagaland border region was done to evaluate the current scenario of drinking water quality in the Assam Nagaland border region where the E sector of Golaghat District, Assam was selected as the study site. Arsenic (As) and fluoride (F^-) levels, as well as other basic water quality indicators like pH, TDS, redox potential, conductivity, resistivity, NaCl, Nitrate, Sulfate, Iron, and Phosphate, were analyzed. Levels of F^- (1.27-1.95 mg/l) and As (0.012 - 0.151 mg/l) were found higher than the permissible limit of WHO and Indian standards, which is not safe for drinking. The presence of a higher level of A, F^-, and Fe²⁺ in drinking water at the study site may be primarily due to the hydro-geochemical process. The Hydro-geochemical process in the underground rock leads to the mobilization of these contaminants into aquifers. Although the drinking water quality standards in this study area are not an immediate threat to human health, their long-term impact on human health harms conditions such as cardiovascular disease, cerebrovascular diseases, renal disorders, and diabetes. Groundwater conservation and awareness about safe drinking water quality, governmental support, health, and hygiene are required for immediate concern in this study area for the better health of people.

1. Introduction

The inorganic form of arsenic (As) and fluoride (F^-) at a disproportionate level in drinking water is a global problem. Most cases of fluoride (F^-) and arsenic (As) contamination have been reported from Asian countries, such as India, Pakistan, Bangladesh, and China. Incongruent weathering of underground rocks and rock-water interaction, or anthropogenic activities, initiates the dissolution and mobilization of these two elements into the aquifers. The ubiquitous distribution of these contaminants in aquifers directly depends on its Geographical and regional climatic conditions.

“Under strong reducing conditions, natural arsenic (As) release from soil sediment could result in elevated arsenic (As) levels in groundwater, and that has the greatest geochemical effect on the largest geographic areas”. ¹

According to the World Health Organization, at least 140 million people all over the world are suffering from arsenicals and fluoride toxicity where groundwater is used for drinking. In India, especially in the Gangetic plain and Brahmaputra river valley, arsenic and fluoride have been reported as dominant contaminants in groundwater.

Above the WHO permissible level of Arsenic (As), Fluoride (F^-), and Iron (Fe²⁺) in drinking water and its related toxicity is a serious matter of concern. In India, west Bengal and Assam are the two major states that have been severely affected by severe groundwater arsenic and fluoride contamination as per the research report. These two silent chemical killers are thought to be poisonings more than 20 million people’s lives in Bangladesh, which is one of the largest poisonings in history due to its geographical position in the delta of the Ganga-Brahmaputra.

Of 3% of the Earth's freshwater, only 0.01% is eligible for drinking. According to the World Health Organization (WHO), the maximum permissible limit of arsenic in drinking water is 0.01 mg/l (0.01 ppm), and for fluoride, the maximum permissible limit is 1.0 mg/l (1ppm). The maximum permissible limit of iron (Fe) in drinking water is 0.3 mg/l (0.3 ppm) as approved by WHO and the Bureau of Indian Standards. ² The source and methods of entering arsenic or fluoride in groundwater are mainly geochemical processes or anthropogenic interventions.

Chronic fluoride or arsenic exposure to human health is associated with skeletal fluorosis, nephrotoxicity, cancer of the skin, lung, liver, urinary bladder, and kidney ^{3, 4, 5} and other diseases, including cardiovascular and peripheral vascular diseases, diabetes, peripheral neuropathies, portal fibrosis, and adverse birth outcomes. ⁶ Chronic iron consumption in drinking water may lead to a genetic disorder called hemochromatosis and other related problems such as abdominal pain, joint pain, and weakness. ⁷

Assam Nagaland border is one of the major interstate disputes in India has been pending in the Supreme Court on the issue since 1988. Assam and Nagaland share a 434 km boundary and a dispute that has been going on for over five decades. About 66,000 hectares of land are in dispute between the states; this includes over 42,000 hectares in Golaghat alone.

For the administrative governance of Assam, the Assam-Nagaland interstate border area has been split into six sectors-A, B, C, D, E, and F- spread over Sivsagar, Jorhat, Golaghat, and Karbi-Anglong districts. All of these sectors are present in Assam. This decades-old dispute has given rise to violence over the years, leading to massive killings and displacement of people, and has become a constant cause of concern between the two states.

The Golaghat district occupies an area of 3502 km² and lies 100 m above sea level. It’s geographical location is 26^o31'12" N and 93°58′12′′ E. It receives an average annual rainfall of 1300mm.

Golaghat district shares its boundary in the E sector with a 38-kilometer long boundary with Nagaland. As per the 2011 census, around 1 lakh people are living within this boundary line. People living along this borderline are always in tension about abduction by Naga insurgents, lack of proper communication, and other basic amenities from the state government.

Drinking water is a major problem in this borderline area. For being a hilly border area, scarcity of drinking water is a serious problem that has been seen in the area. Most people have to depend on surface water. The main sources of drinking water in this area are open ring wells or tube wells. Some People use a traditional sand-charcoal-based filter system to drink water. Most people do not use any filter system, they directly use drinking water from ring wells or tube wells.

A higher level of Arsenic (As) and Fluoride (F^-) has been reported from different districts of Assam in the earlier research report. 24 districts of Assam have been reported to have the presence of severe arsenic contamination, while 13 districts have been affected by severe fluoride levels in drinking water.

Several research studies have been reported about the groundwater quality of Golaghat district, in the following blocks i.e. Dergaon, Kathalguri, Podumoni, Kakodonga, Morangi, and Gamariguri ⁸ but there are no specific data regarding drinking water quality, particularly in the disputed borderline area. The quality of drinking water has not been studied especially in the said boundary area. Lack of proper communication, fear of Naga extremists, and illegally occupied land of Assam by Nagas may be the possible reasons for not being studied in this disputed area.

Therefore, a rapid survey was done in December 2021 in the borderline dispute area of Golaghat district to assess the drinking water quality of that region so that these data would be helpful for the government or any agencies to carry out better management of drinking water and health hygiene in that particular disputed area.

2. Methods and Methodology

A rapid random sampling and survey were accomplished to access drinking water quality in the Golaghat district-Nagaland border in December 2020. Water samples were collected from at least 10 feet underground sources such as tube wells and ring wells.

A 0.45 mm membrane filter was used to filtrate samples and kept in 125 mL LDPE polyethylene bottles that were pre-washed with HNO₃ and water (1:1) for metal analysis.

After collection, 2 to 3 drops of concentrated HNO₃ were added as a preservative. For analysis of fluoride (F^-), nitrate (NO₃^-), iron (Fe²⁺), sulfate (SO₄^-), and phosphate (PO₄^3-), raw samples were filtered and collected in 250 ml polyethylene bottles. Basic water quality parameters (pH, Oxidation-reduction potential (ORP), Conductivity, resistivity, total dissolved solids (TDS), NaCl) were analysed using a mobile water testing kit in-situ.

The study area was divided into 20 different blocks, and on average, at least 3 samples were collected from each block within a radius of 1 km. Samplings sites were recorded using the Garmin eTrex GPS machine. A total of 60 samples (n=60) were collected. Analysis of collected samples was carried out in the Department of Environmental Science, Gauhati University, and Indian Institute of Technology (IIT), Gandhinagar, Gujarat.

Estimation of fluoride (F^-) was performed by using UV-VIS double beam spectrophotometer (model: systronic-2206) and ions electrode method. Analysis of heavy metal, especially Arsenic (As) was done using ICP-MS (inductively coupled plasma mass spectrometry) to get the accurate result after proper digestion process with concentrated nitric acid. The other parameters such as level of nitrate (NO₃^-), iron (Fe²⁺), sulfate (SO₄^-), phosphate (PO₄^3-), were analyzed as per APHA guidelines. (N=60)

3. Results and Discussion

Both the level of fluoride (F^-) and Arsenic (As) were found above the permissible limits set by WHO and Indian water quality standards in this study. Other basic water quality parameters were found normal except the level of Iron. (Table 3) The iron level had been found more than 5 fold higher in almost all the analyzed samples.

The detection of relatively higher levels of fluoride (1.27-1.95 mg/l) and arsenic (0.012-0.151 mg/l) in water samples (Table 4) may be due to geological mobilization of fluoride and arsenic in the groundwater aquifers in the study area because the entire belt lies parallel to the foothills of the Naga Hills. A negative correlation between arsenic (As) and ORP indicates mobilization of arsenic to underground waters under reduced conditions. ⁹ pH was found positively correlated with both arsenic (R-value: 0.46121) and fluoride (R-Value: 0.167455) in all collected water samples.

Apart from the elevated levels of arsenic and fluoride, drinking water has been found a high level of iron (2.40-4.79 mg/l) (Table 3) as most of its sources are open ring wells and a few tube wells. Since Iron oxides are a dominant chemical compound in red soils in Naga Hills so, quick mobilization of iron into drinking water takes place.

Due to underground rocks, it is not possible to the installation of borewell pipes more than 15 feet below is not possible. Hence, people mainly depend on Ring wells and a few tributaries of Naga Hills as the main sources of drinking water. No serious fluorosis or arsenicosis was reported on the study site, except for a few dental fluorosis.

The regular uptaking excess level of Fluoride or arsenic in drinking water may cause serious health hazards. Though Iron, Fluoride, and arsenic levels had been found slightly above the WHO’s permissible limit in the assessment of drinking water quality, which is not an immediate threat to human health.

However, other related diseases such as cerebrovascular disease, liver cirrhosis, chronic kidney disease, diabetes, and hemochromatosis may occur as a result of the daily use of drinking water sources in this entire belt region.

4. Conclusion

Arsenic (As) and Fluoride (F^-) behave differently in aquifers based on their affinity to other ions in the aquifer. Incongruent Dissolution of A and F^- and their mobilization from the underground rocks into the groundwater aquifer directly depend upon natural processes.

The result shows that both the levels of F^- and As are relatively higher than the WHO permissible limit in the entire Assam Nagaland belt area. Geological dissolution from underground rocks of Naga hills is the potential natural source of As and F^- in this belt region. Internal remote area and least developed in this belt region denies the probability of industrial influx of these two pollutants. So far in the present scenario, the study reveals that the groundwater quality is not safe to drink as per WHO’s guidelines in the study area.

People living in the disputed areas across the Assam-Nagaland border always face harsh conditions. Lacks of proper education, basic amenities, negligence of governance, fear of Naga extremists, lack of drinking water, sanitation, health hygiene, and women’s health care are big issues in the study area.

It is urgent to make an awareness campaign about drinking water, health hygiene in the entire belt area. Government must facilitate suitable drinking water facilities under the Jal Jeevan mission in that study area with all basic amenities of life. Besides community education, the implementation of best practices for the safe use of groundwater sources must be done in an effective way.

Acknowledgements

The Authors are thankful to Dr. Arbind Kumar Patel, IIT-Gandhi Nagar, Gujrat for his valuable help and necessary guidance.

References