A chemometric and ingestion hazard prediction study of groundwater in proximity to the Bandhwari landfill site, Gurugram, India

Water is the most valuable resource on the planet and is regarded as an essential requirement for life and the country's economic progress (Malik et al. 2024). The health of the population of an area is significantly determined by the quality of water. Groundwater is the most crucial water source for any nation and has a critical role in the community's health especially in countries like India, where groundwater supplies 90% of the country's water demands (Khyalia et al. 2023). India's 60% demand for agriculture is fulfilled by groundwater (Bhattarai et al. 2021). Despite the significant reliance on subsurface water supplies, groundwater contamination has resulted from a variety of sources, viz. irrigation water percolation, septic tank spillages, industrial effluent disposal, and toxic chemical leaching from dumpsites, all of which have degraded the quality of groundwater resources and rendered them unfit for use (Sarvajayakesavalu et al. 2018; Przydatek & Kanownik 2019; Siwila & Buumba 2021). India with its 1.39 billion people is the second most populated country in the world, preceding China (1.44 billion), and with the current rate of population growth, India has been predicted to have more than 1.53 billion people by the end of 2030 (Omolola et al. 2023). Rapid growth in urbanization, industrialization, and economic development coupled with an ever-increasing population and a changing lifestyle has resulted in the amplified generation of municipal solid waste. Currently, the disposal and management of municipal solid waste are one of the major environmental concerns faced by both developed and developing countries. The most common methods of waste disposal in India are open dumping and landfills because they do not require skilled workers and sophisticated technology (Narayana 2009). Though landfills provide a quick and easy solution, according to Lee & Jones (1993), the disposal of municipal solid waste by landfilling has proven to be one of the main culprits behind groundwater pollution as the waste in landfills undergoes various chemical, physical, and biochemical reactions and generates leachate as a by-product. Various studies have been conducted at different landfill sites to understand their role in groundwater contamination (Acharya et al. 2018; Abiriga et al. 2020; Amano et al. 2021; Podlasek et al. 2021).

The area near the landfill site is usually more vulnerable to groundwater pollution (Singh et al. 2008; Njoku et al. 2019). The leachate produced by landfills is composed of concentrated complex effluents containing waste products such as humic acids, NH₃, Ca, Fe, Na, Mg, K, ⁠, Cl⁻ with heavy metals, viz. Cd, Cu, Pb, Cr, Zn, and anthropogenic xenobiotic compounds (Kjeldsen et al. 2002; Boateng et al. 2019). These pollutants have detrimental impacts on aquatic life, the ecology, and the food chain, leading to various health problems like carcinogenic effects, acute toxicity, and genotoxicity (Gajski et al. 2011). Therefore, the improper and unscientific disposal of this municipal solid waste has an adverse impact on all the components of the environment (Sharma et al. 2018). The study documented here was carried out to measure the impact of the Bandhwari landfill on the groundwater quality of surrounding areas. Groundwater quality in the landfill region was checked for several physicochemical parameters of collected samples, with a concentration of selected heavy metals including Fe, Cd, Pb, Zn, Cu, Ni, and Cr. The health risk from consumption of the studied groundwater samples was also calculated to develop clarity about the risk from groundwater use.

The Bandhwari landfill site is one of the largest landfill sites in Northern India and it is situated in Bandhwari village of Gurugram on Gurugram-Faridabad National Highway-48. Bandhwari village has a population of 3,624 people living in around 557 households. Bandhwari landfill site is an open dumping site which was established in 2009 and since then, the site has been accommodating waste from Gurugram and Faridabad. This landfill is 37.2 m high and is spread across an area of nearly 30 acres on the Faridabad-Gurugram road. According to a report submitted by the Municipal Corporation of Gurugram (MCG) to the National Green Tribunal (NGT), the landfill receives around 1,800 tonnes of fresh municipal waste every day (TOI 2021). As per NGT's latest order, the quantity of untreated waste at the landfill has increased to 40 lakh tonnes now. The landfill was built on an old mining pit with a depth of 250 feet in the proximity of groundwater aquifers and the site is also very close to the last remaining area of the Aravalli forest, a sacred groove for the natives. So, landfill is extremely harmful to biodiversity and human health as it is not only causing a substantial amount of pollution but also disturbing the ecologically vulnerable Aravalli range.

The analysis and measurement of physicochemical parameters along with heavy metals in collected groundwater samples were carried out as per the standard methods described using standard methodology (APHA 2017).

The pH with electrical conductivity (EC) was assessed in situ, using a digital pH meter (HM Digital, pH-200) and a digital EC meter (HM Digital, aquapro), respectively. Total dissolved solids (TDS) content was measured using the gravimetric method, and total alkalinity (TA) was analyzed using acid–base titrimetric methods (APHA 2017). Total hardness (TH), calcium (Ca²⁺), magnesium (Mg²⁺), and chloride (Cl⁻) were also analyzed by the titrimetric method. Alkali metals such as sodium and potassium contents were analyzed using a Digital Flame Photometer (Esico, Model-381). A UV-visible spectrophotometer was used to determine sulphate (APHA 2017). Heavy metals like lead, iron, nickel, copper, and zinc were estimated by using an atomic absorption spectrophotometer (Shimadzu, AA-6880).

A hazard quotient is a process of evaluating the adverse health effects of human exposure to environmental hazards. In the present study, it was done by calculating the target hazard quotient using the United States Environmental Protection Agency (USEPA) methodology. The total hazard quotient (THQ) is the ratio of exposure to toxic elements to the reference dose prescribed, which is the maximum concentration at which no adverse health effects are expected (Johann et al. 2017). The value of THQ was calculated using methodology prescribed by USEPA (2012) and Singh & Garg (2022).

THQ = Concentration of exposure/Concentration prescribed as reference

Concentration of exposure =EFr × ED × WI × MCW × 0.001

The THQ is basically the evaluation of the non-carcinogenic health risk presented by exposure to a particular toxic element. If THQ is less than 1, then non-carcinogenic health effects are not seen. However, if THQ is more than 1, it indicates the possibility of adverse non-carcinogenic health effects (Akande et al. 2019).

A comprehensive investigation of groundwater quality was done for 18 groundwater sampling locations from the surroundings of the landfill area to evaluate the degree of contamination caused by downward infiltration and horizontal migration of leachate from the landfill site.

The pH of the groundwater samples was from 6.7 to 7.7, which demonstrates that the groundwater is slightly acidic to alkaline in nature and for all the samples were within the permissible limit prescribed by Bureau of India Standards (BIS 2012), i.e., 6.5–8.5. The EC of the groundwater samples ranged from 1.15 to 6.69 mS/cm, which is beyond the BIS permissible limit of 2.5 mS/cm. EC was reported at its maximum at sampling site S1, followed by site S2, which were proximal to the Bandhwari landfill site. This could be due to the percolation of salts and minerals into the groundwater from the leachate. Similar results were reported by Kuriakose et al. (2016), who reported a high value of EC (>2.6 mS/cm) in groundwater samples collected from the vicinity of the Okhla landfill site, Delhi. According to WHO (2008), TDS is generally used to determine the salinity and overall quality of water. The concentration of TDS in all the samples ranged from 231 to 2,240 mg/L and the highest concentration of TDS was found at site no. 18. The TDS of around 67% of the samples exceeded the BIS permissible limit of 500 mg/L. Furthermore, the high TDS content in groundwater which is present around the landfill site renders it unsafe for drinking and may induce gastrointestinal irritation (Kuriakose et al. 2016). The TA was reported to occur between 216 and 852 mg/L. The highest alkalinity values were reported at sampling site S2 and the lowest was at S10. All the assessed groundwater samples were found to have values exceeding the BIS permissible limits of 200 mg/L. The results of the present study were supported by the study conducted by Alam et al. (2020), who reported a very high range of alkalinity (2,123–3,256 mg/L) in the groundwater samples collected from the vicinity of the Ghazipur landfill site, Delhi. The degree of hardness in water depends on the concentration of calcium and magnesium ions (Tanwer et al. 2023a). The TH values ranged between 168 and 1,220 mg/L, with the highest being at S1 and the lowest at S4. Almost all the samples were very hard and exceeded the BIS permissible limit, i.e., 200 mg/L. The Ca²⁺ values were in the range of 46.49–184.36 mg/L with an average of 99.47 mg/L; more than 50% of the samples were found to exhibit calcium values exceeding the BIS permissible limit of 75 mg/L. Excess Ca²⁺ in the body creates health issues in the body such as kidney stones or calculi, as well as inflammation in the urinary tract. Calcium may enter groundwater aquifers via limestone, marble, calcite, and gypsum (Bozdağ 2016). Magnesium is the second-most abundant cation in the cells (Fawcett et al. 1999). The minimum concentration of Mg²⁺ found in groundwater samples was 10.65 mg/L whereas the maximum concentration was 252.6 mg/L, with a mean value of 59.52 mg/L. 15 out of 18 groundwater samples were found to exhibit Mg²⁺ values exceeding the BIS permissible limit (30 mg/L) of drinking water standards. Excessive intake of Mg²⁺ salts may cause diarrhoea also (Sengupta 2013). Similarly, a high value of Mg concentration (329.3–369.26 mg/L) in the leachate from Bhalswa landfill was also reported by Ahamad et al. (2019). The sodium salt is found in almost every food item and drinking water and, as per the BIS acceptable limit, the sodium content should not exceed 200 mg/L. In the present study, all the groundwater samples were lower than the highest permissible limit of Na as they ranged between 19 and 162 mg/L; all the samples showed acceptable conditions. The amount of K in the groundwater samples varied from 1.5 to 9.2 mg/L, with an average of 3.8 mg/L. So, all the groundwater samples were within the acceptable range regarding K content. Along with geological composition, Cl⁻ concentration in groundwater is influenced by anthropogenic activities consisting of improper management of septic tanks, sewage disposal, and animal waste (Tanwer et al. 2023b). Its concentration in the groundwater samples ranged from 34 to 474 mg/L (an average of 116.09 mg/L). Cl⁻ in all the samples, except from site S1 (474 mg/L), which was adjacent to the landfill, were below the BIS desirable limit, i.e., 250 mg/L. Sudha et al. (2021) studied the hydro-chemical characterization of groundwater quality near the municipal solid waste dumping site at Vellalore in Coimbatore and found that a Cl⁻ plume (854 mg/L) was affecting the water resources. Rocks, fertilizers, and the burning of fossil fuels are the main sources of groundwater. It can be found in almost all natural waters. A higher level of present in drinking water can have laxative effects if present alongside Ca²⁺ and Mg²⁺ (Tanwer et al. 2023b). In the present study, the concentration in almost all the groundwater samples except for S11 (273 mg/L) was significantly lower than the BIS (2012) permissible limit of 200 mg/L.

The results of the samples analyzed for the site under study revealed that the samples closest to the landfill site are the most affected by the leachate produced by the landfill. Other affected samples located far from the landfill site could be the result of an unlined wastewater drain, quaternary aquifer over-extraction or other anthropogenic influences in the research area. Table 2 shows the detailed measured values of various physicochemical parameters of chosen groundwater samples as well as their comparison with BIS (2012), EU (2020) and WHO (2017) permissible criteria.

Table 2

Physicochemical analysis of groundwater samples from the Bandhwari landfill site area

S.No. .	pH .	EC (ms)/cm .	TDS (mg/L) .	TH (mg/L) .	TA (mg/L) .	Ca2+ (mg/L) .	Mg2+ (mg/L) .	Na+ (mg/L) .	K+ (mg/L) .	(mg/L) .	Cl− (mg/L) .
1	7.1	6.59	1,318	1,200	532	65.73	252.6	112	5.1	79.3	474
2	6.8	6.38	1,276	800	852	184.36	82.7	162	9.2	18.6	125
3	7.6	5.25	1,050	332	564	83.36	30.14	141	8.4	273	202
4	7.2	1.53	307	168	324	48.09	11.65	47	2.6	18.6	46
5	7.1	3.7	740	324	576	78.55	31.12	77	2.4	15.3	98
6	7.4	2.15	1,430	296	452	62.52	34.07	61	1.8	28.3	56
7	7	1.56	313	196	256	60.92	10.65	28	2.3	74.1	36
8	7.7	1.39	280	208	300	54.5	39.93	29	2.0	37.6	52
9	7.5	2.44	488	320	508	46.49	49.7	62	3.2	16.3	102
10	6.9	1.15	231	244	216	51.3	28.23	19	1.5	35.2	34
11	7.6	1.91	382	224	588	81.76	41.78	41	2.7	26.3	52
12	7.5	2.62	1,120	980	352	144.12	67.96	46	3.2	25.6	45
13	7.3	2.14	1,436	1,046	456	153.82	72.54	58	4.6	48.7	49
14	6.7	3.4	1,640	1,220	321	179.41	84.60	24	2.1	56.4	56
15	7.1	1.98	968	456	364	67.06	31.62	38	1.8	19.8	46
16	7.3	2.35	1,376	780	412	114.71	54.09	98	4.6	28.6	84
17	7	4.18	1,630	964	256	141.76	66.85	74	7.1	45.3	74
18	7.4	5.7	2,240	1,170	532	172.06	81.14	80	3.2	47.5	62
IS-10500 (BIS 2012 )	6.5–8.5	2,250 at 25 °C	500	200 (600)a	200 (as CaCO3)	75	30	–	–	200	250
WHO (2017)	6.5–8.5	–	600	300 (500)a	–	75–200	–	200	–	250	200–300
EU (2020)	6.5–8.5 (up to 9.5)	2,500 at 20 °C	500	150–500a	–	100	–	200	–	250	250

S.No. .	pH .	EC (ms)/cm .	TDS (mg/L) .	TH (mg/L) .	TA (mg/L) .	Ca2+ (mg/L) .	Mg2+ (mg/L) .	Na+ (mg/L) .	K+ (mg/L) .	(mg/L) .	Cl− (mg/L) .
1	7.1	6.59	1,318	1,200	532	65.73	252.6	112	5.1	79.3	474
2	6.8	6.38	1,276	800	852	184.36	82.7	162	9.2	18.6	125
3	7.6	5.25	1,050	332	564	83.36	30.14	141	8.4	273	202
4	7.2	1.53	307	168	324	48.09	11.65	47	2.6	18.6	46
5	7.1	3.7	740	324	576	78.55	31.12	77	2.4	15.3	98
6	7.4	2.15	1,430	296	452	62.52	34.07	61	1.8	28.3	56
7	7	1.56	313	196	256	60.92	10.65	28	2.3	74.1	36
8	7.7	1.39	280	208	300	54.5	39.93	29	2.0	37.6	52
9	7.5	2.44	488	320	508	46.49	49.7	62	3.2	16.3	102
10	6.9	1.15	231	244	216	51.3	28.23	19	1.5	35.2	34
11	7.6	1.91	382	224	588	81.76	41.78	41	2.7	26.3	52
12	7.5	2.62	1,120	980	352	144.12	67.96	46	3.2	25.6	45
13	7.3	2.14	1,436	1,046	456	153.82	72.54	58	4.6	48.7	49
14	6.7	3.4	1,640	1,220	321	179.41	84.60	24	2.1	56.4	56
15	7.1	1.98	968	456	364	67.06	31.62	38	1.8	19.8	46
16	7.3	2.35	1,376	780	412	114.71	54.09	98	4.6	28.6	84
17	7	4.18	1,630	964	256	141.76	66.85	74	7.1	45.3	74
18	7.4	5.7	2,240	1,170	532	172.06	81.14	80	3.2	47.5	62
IS-10500 (BIS 2012 )	6.5–8.5	2,250 at 25 °C	500	200 (600)a	200 (as CaCO3)	75	30	–	–	200	250
WHO (2017)	6.5–8.5	–	600	300 (500)a	–	75–200	–	200	–	250	200–300
EU (2020)	6.5–8.5 (up to 9.5)	2,500 at 20 °C	500	150–500a	–	100	–	200	–	250	250

^aIn the absence of a substitute source.

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The correlation among the metals analyzed was also studied using IBM SPSS Statistics 22 and significant positive correlations were observed between Pb and Zn (r = 0.758, p ≤ 0.01), Pb and Ni (r = 0.814, p ≤ 0.01), Pb and Cu (r = 0.872, p ≤ 0.01), Zn and Ni (r = 0.798, p ≤ 0.01), Ni and Cu (r = 0.813, p ≤ 0.01) and Zn with Cu (r = 0.891, p ≤ 0.01); while a significant negative correlation was found between Cr and Cd (r = −0.594, p ≤ 0.01). It shows that Pb coexisted in water with Zn, Ni and Cu while Zn also exhibited coexistence with Ni and Cu (Supplementary material, Table S1). Further studies with controlled natural attenuation processes have been recommended by various authors for the coexistence and migration of these metals in groundwater. The major reasons provided in the literature are pH, dissolution and solubility of metals in groundwater (Xu et al. 2015; Shrestha et al. 2016; Mahapatra & Nimmy 2021).

The major pathways which can introduce metals into the human body are ingestion through food and water, inhalation (through smoke, fumes or dust), radiation exposure and dermal contact with metals (Duhan et al. 2022; Sharma et al. 2023; Tanwer et al. 2023c). Different metals can cause different types of risks to the human body including neurotoxicity, nephrotoxicity, hepatotoxicity etc. (USEPA 2005; Tanwer et al. 2022; Duhan et al. 2023). Various studies have been conducted globally to estimate heavy metals in groundwater (Kana 2022; Mawari et al. 2022; Ullah et al. 2022). Tong et al. (2021) also studied and reported THQ values for As, Co, Cd, Fe, Pb, Ni, Zn and Cu in groundwater from different areas of China and documented it to be safe except for arsenic content. Negligible health risk from consumption of Zn, As and Fe in groundwater was reported by Anim-Gyampo et al. (2019) from the Atankwidi basin of Ghana due to their very low concentration while it was reported to pose a significant risk from greater concentration of Pb in the same water. Maigari et al. (2016) documented significant risk for children and adults due to ingestion of Fe, Ni, Mn, and Co via drinking groundwater. There have been some other studies including Vetrimurugan et al. (2017) from the Cauvery river basin, Tamil Nadu, India in context to Mn, Pb, Ag, Cd and Ni; Islam et al. (2017) reporting arsenic risk from groundwater consumption in Chapai-Nawabganj district, Bangladesh; Hossain et al. (2020) documenting the risk from various metals present in groundwater from Dinajpur, Bangladesh. In comparison to these referenced studies, the values of THQ in the presented study imply that the region of Bandhwari landfill site is not a risk in consideration with Cd, Pb, Fe, Ni, Cu, Zn, and Cr content in the groundwater.

Water quality assessed for the Bandhwari landfill site region indicated that groundwater from the study area depicted some of the physicochemical characteristics in the greater concentration as compared to the prescribed limits by the World Health Organization and Indian Standards. The presence of metals, viz. Pb with Zn, Ni and Cu; Zn with Ni and Cu were found to be in positive correlation. The values of Pb were found to be in correlation with other metals hence showing no inhibition in migration and diffusion of metals. No significant health risk was observed due to the presence of analyzed metals in groundwater as per THQ values calculated although the THQ values were significantly higher for Pb and Cd in comparison to other studied metals. This study may be useful for future studies for the analysis of trends in metal concentration and groundwater parameters in the vicinity of Bandwari landfill site.

No ethical approval is required as no living organism/plant or human was subjected to research.

V.W. and L.B. were involved in the execution of the sampling/analysis work; V.M. was involved in conception and design of the work; M.S. was involved in data analysis, interpretation writing, and proofreading; P.K. was involved in statistical analysis and proof reading.

No funding was received for the research work.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.