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Environ Geochem Health (2006) 28:473–485 DOI 10.1007/s10653-006-9053-1
ORIGINAL PAPER
Distribution of nitrogen species in groundwater aquifers of an industrial area in alluvial Indo-Gangetic Plains—a case study Kunwar P. Singh Æ Vinod K. Singh Æ Amrita Malik Æ Nikita Basant
Received: 20 September 2005 / Accepted: 10 May 2006 / Published online: 22 June 2006 Springer Science+Business Media B.V. 2006
Abstract The groundwater samples collected from the shallow and deep groundwater aquifers of an industrial area of the Kanpur city (Uttar Pradesh, India) were analyzed for the concentration levels and distribution pattern of nitrogenous species, such as nitrate-nitrogen (NO3-N), nitrite-nitrogen (NO2-N), ammonical-nitrogen (NH4-N), organic-nitrogen (Org-N) and total Kjeldahl-nitrogen (TKN) to identify the possible contamination source. Geo-statistical approach was adopted to determine the distribution and extent of the contaminant plume. In the groundwater aquifers NO3-N, NO2-N, NH4-N, TKN, Org-N and Total-N ranged from 0.10 to 64.10, BDL (below detection limit)-6.57, BDL-39.00, 7.84–202.16, 1.39–198.97 and 8.89–219.43 mg l–1, respectively. About 42% and 26% of the groundwater samples of the shallow and deep groundwater aquifers, respectively, exceeded the BIS (Bureau of Indian Standards) guideline value of 10 mg l–1 for NO3-N and may pose serious health hazards to the people of the area. The results of the study revealed that the groundwater K. P. Singh (&) Æ V. K. Singh Æ Amrita Malik Environmental Chemistry Section, Industrial Toxicology Research Centre, Post Box 80, MG Marg, Lucknow 226 001, India e-mail: [email protected] N. Basant AAI-DU, Allahabad, India
aquifers of the study area are highly contaminated with the nitrate and indicates point source pollution of nitrate in the study area. Keywords Industrial area Æ Contamination Æ Nitrate pollution Æ Point source Æ Fertilizer industry
Introduction Nitrate is found in most of the natural waters at moderate concentrations but is often enriched to the contaminant level in the groundwater resources mainly from the excessive use of fertilizers and uncontrolled on-land discharge of raw and treated wastewater (Shrimali & Singh, 2001). Nitrogen chemistry is complicated by the multiplicity of oxidation states, the element assumes in its compounds. Nitrate (NO3), nitrite (NO2), ammonia (NH3), and organically bound forms of nitrogen (Org-N) are the species of interest for water resource management. Various forms of nitrogen (oxidized and reduced) are present in many possible recharge sources of urban aquifers. Nitrate contamination of the groundwater in different parts of India and other regions of the world has been reported (Datta, Deb, & Tyagi, 1997; Laftouhi, Vanclooster, & Jalal, 2003; Namade & Srivastava, 1997; Pandey & Mukherjee, 1994a, b; Reid, Edwards, Cooper, Wilson, &
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Mcgraw, 2003; Wakida & Lerner, 2005). Nitrate has been linked to agricultural activities due to the use of nitrogenous fertilizers. The non-agricultural sources include leakage from water supply and disposal networks, on-site sewage disposal, animal waste, contaminated land, industry, river and aquifer interaction, atmospheric deposition, urban fertilizer use, storm water, house building, and direct recharge (Wakida & Lerner, 2005). Among these industries are the potential sources of nitrogen to the groundwater. Nitrogen compounds are used extensively in the industrial processes such as plastic and metal treatments, raw materials for the textile industry, particle board and plywood, household cleaning, fertilizers and the pharmaceutical industry. Contaminated lands such as abandoned landfills, gasworks site or abandoned industrial sites contribute a significant quantity of nitrogen to groundwater. Landfills are considered a major source of pollutants and their impacts on groundwater quality have been reported (Albaiges, Casado, & Ventura, 1986; Flyammar, 1995). In developing countries landfills are usually open dumping sites for disposal of domestic/industrial wastes. Pollutants from these sites may percolate down to sub-soil and groundwater aquifers under natural set of environmental conditions prevailing in the region. Groundwater and surface water contamination with nitrogenous species can cause health problems in infants and animals as well as the eutrophication of water bodies (Fennesy & Cronk, 1997). Nitrate ion has been identified as a potential health hazard to infants and pregnant woman (Chan, 1996). The nitrate ion is responsible for the disease ‘methaemoglobinemia’ or ‘blue-baby syndrome’ (Benefield, Judikins, & Weand, 1982). Under certain conditions, nitrate can be converted into much more poisonous nitrite and even to a carcinogenic nitrosamine (Richard, 1980) which primarily affects the oesophagus and pharynx (gastrointestinal tract). Groundwater constitutes major source of water for domestic, drinking, and industrial purposes in Kanpur city, which is one of the important industrial centers in northern India. There are more than 800 industries in the city involved in manufacture of wide variety of products such as textiles, leather, drugs, chemicals, fertilizers,
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plastics, cold drinks and edibles, etc. Out of the total drinking water demand of about 500 million l per day (mld), more than half is met by the groundwater sources, whereas, for the industrial purposes, water requirements are mainly met through groundwater sources. Subsequently, a huge amount of domestic and industrial wastewater is generated. The current total capacity of wastewater treatment plants in the city is about 142 mld. Panki, Dada Nagar, Armapur and Jajmau are the established industrial areas within the city. In Panki industrial area, mainly chemical based industries are operating including one major fertilizer industry manufacturing urea. The effluents so produced are generally rich in ammonia and other nitrogen species and there are the possibilities for the contamination of groundwater aquifers with the nitrogen-species. The rivers, streams and ponds are among the main surface water sources in the region, while the dug well, tube well, bore well and hand-pump constitute the groundwater sources. The groundwater in the study region occurs mostly at shallow depth aquifers with water level depth of less than 10 m below the ground level. This study focuses on the concentration levels and distribution of various nitrogen species in groundwater aquifers of Kanpur City, with an attempt to identify the source of contamination and delineate its boundaries for remedial purpose to safeguard the public health, as groundwater is the major source of domestic, drinking, and industrial water supplies in Kanpur city.
Materials and methods Study area Kanpur, the eighth largest city of India, is an industrial town located (latitude N 2620¢ and 2635¢ and longitude E 8010¢ and 8030¢) in the Central Alluvial Ganga Plain (Fig. 1). It encompasses an area of about 1040 km2 with a population of more than 2.53 million (Census, 2001). The present study is confined to the Panki industrial area. In the study region, a three-tier aquifer system viz., shallow, middle and deep aquifers, exists
Environ Geochem Health (2006) 28:473–485
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Fig. 1 Map of the study area showing sampling locations
down to bedrock and the aquifers are connected through the clay beds. Shallow aquifers, consisting of very fine-to-fine sand, occur down to 150 m
bgl (below ground level). Middle aquifers, consisting of fine to medium sand, occur between 150 m and 250 m and deep aquifers occurring
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between the depths of 250 m and 400 m bgl consist of medium to coarse sand and gravel. The groundwater in the deeper aquifers occur under confined and semi-confined conditions, whereas, near surface groundwater in the phreatic zone (thickness about 50 m bgl) is unconfined and is tapped by shallow hand pumps and dug wells. The groundwater in the investigated area originates from a combination of rainfall, river/canal water and irrigation water flow. Ground water in the deeper aquifers is mostly recharged through leakage from the upper unconfined aquifer and partly from lateral groundwater flow from the north and north-east.
Environ Geochem Health (2006) 28:473–485
of nitrate and nitrite, respectively. Ammonia (NH4-N) was determined spectrophotometrically (nesslerization method) using UV–VIS spectrophotometer (GBC Cintra-40, Australia), whereas total Kjeldahl-nitrogen (TKN) was determined by distillation (Macro-Kjeldhal Method) and titration with H2SO4 (APHA, 1998). TKN is the sum of free ammonia and organic nitrogen compounds. Organic nitrogen (Org-N) was estimated from the difference of TKN and NH4-N in each sample. The total nitrogen (Total-N) is the sum of all nitrogen forms as above. The minimum detection limits for nitrate, nitrite, ammonia and TKN were 0.1, 0.05, 0.02 and 0.2 mg l–1, respectively.
Sample collection and analysis Quality assurance A total of 126 groundwater samples were collected in December 2004 from the Panki Industrial region in Kanpur City (Fig. 1). The study region covering an area of about 6 km2 is demarcated by hydrological boundaries, a fresh water canal in north and Pandu River in south. Samples were collected from the hand-pumps and bore wells spread over the entire study region. Samples from tube wells, bore wells and handpumps were collected from the outlets after flushing water for 10–15 min in order to remove the stagnant water. The water samples were collected in high quality air-tight polyethylene containers. The sample containers were thoroughly cleaned and pre-washed with phosphate free detergent and rinsed with distilled water (Sylvestre, Brewer, Sekela, Tuominen, & Moyle, 1998). The collected water samples were immediately transported to the laboratory in ice boxes under low temperature (4C) conditions and processed immediately for analysis (APHA, 1998). The samples were stored in deep freezer at 4C and the analysis was completed within 24 h. Nitrate (NO3-N) and nitrite (NO2-N) ions were measured by ion-selective electrode method using ionplus combination electrodes: ORION 97-07 NO–3 ion electrode for nitrate and ORION 97-46 NO–2 ion electrode for nitrite equipped with an Ion meter (model 960A, ThermoOrion, USA). Nitrate interference suppressor solution (Orion 930710) and nitrite interference suppressor solution (Orion 934610) were used for determination
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The analytical data quality was ensured through careful standardization, procedural blank measurements, and spiked and duplicate samples. The laboratory also participates in regular national program on analytical quality control (AQC). For NO2-N, NO3-N and NH4-N synthetic solutions in the concentration range of 0.1–100 mg l–1, 0.1– 50 mg l–1, and 0.1–5.0 mg l–1, respectively were prepared separately through spiking of deionized water (DI) with their respective standards (Merck, India). For TKN, glutamic acid (99%, SRL, India) was used as standard for Org-N and spiked solutions (0–5.0 mg-N l–1) in DI water were prepared. Recoveries of the N-species from the spiked water samples (n = 10) were found to be between 94 to 102%. After each batch of 10 samples, series of these spiked solutions were analyzed following the same procedures along with their respective blanks. In all the analysis, blanks were run and corrections were applied, if necessary. All the observations were recorded in duplicate and average values are reported. Appropriate dilutions were applied wherever necessary.
Results and discussions In general, in the groundwater samples collected over the entire study region (shallow and deep aquifers) the NO3-N, NO2-N, NH4-N, TKN,
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Org-N and Total-N ranged from 0.1 to 64.1, BDL6.6, BDL-39.0, 7.8–202.2, 1.4–198.9 and 8.9– 219.4 mg l–1, respectively. In study area the levels of NO3-N were higher then that observed in the groundwater of south Brazil impacted with waste from coal processing activities (NO3-N, 0.40– 3.40 mg l–1; Binotto, Teixeira, Sanchez, Migliavacca, & Nanni, 2000), in the groundwater of Epworth (NO3-N, 0.0–6.74 mg l–1; Zingoni, Love, Magadza, Moyce, & Musiwa, 2005) and in the groundwater of Kakamigahara Heights, Central Japan (NO3-N, 0.49–26.61 mg l1; Babiker, Mohamed, Terao, Kato, & Ohta, 2004). However, levels of NO3-N in study area were lower than reported by Nas and Berktay (2006) in the groundwater of Konya City, Turkey (3.0– 110.0 mg l–1 in the year 2001). Rukah and Alsokhny (2004) have also observed enhanced nitrate concentrations (7.57–90.23 mg l–1) in the groundwater of North Jordan. They attributed this to the discharge of sewage effluents, fertilizers, animal excreta, rainfall and industrial effluents to unsaturated aquifers. The basic statistics of the nitrogen species (N-species) detected in the groundwater samples from the shallow and deeper aquifers of the studied region is given in Tables 1 and 2, respectively. There was observed a wide spatial variation in the levels of different N-species viz. NO3-N, NO2-N, NH4-N, TKN, Org-N and Total-N determined in the groundwater samples collected from the study region. It was also observed that mean concentration level of NO3-N (14.7 mg l–1) and NH4-N (2.0 mg l–1) in shallow aquifers were relatively higher than that observed in the deeper aquifers (NO3-N, 9.6 mg l–1; NH4-N, 1.54 mg l–1). Further, the mean concentration levels of NO3-N were higher
than that of NH4-N and NO2-N in both the shallow as well as deeper aquifers. Lee, Min, Woo, Kim, and Ahn (2003) have also reported higher concentrations of NO3-N in shallow wells as compared to the deep wells in the groundwater of Seoul (Korea). This may be attributed to the fact that nitrate, as compared to other nitrogen species, does not attach to soil particles and is easily moved to groundwater. In addition, if depth to groundwater is shallow and the underlying soil is sandy, as in the study region, the potential for nitrates to enter groundwater is relatively high (Killpack & Buchhalz, 1993). Moreover, the extra-ordinary aqueous solubility of nitrates imparts higher mobility to the ion with the groundwater flow. Figures 2 and 3 present the histograms for the frequency distribution of various N-species (NO3-N, NO2-N, NH4-N, Org-N, and TKN) in groundwater aquifers suggesting skewed (non-normal) distribution in both the shallow (Fig. 2) and deep (Fig. 3) aquifers. The skewed frequency distribution of the N-species suggests groundwater contamination from both point and non-point sources of pollution. The distribution of Org-N and TKN showed almost similar trends in the deep groundwater aquifers (Fig. 3d and e, respectively). This may be due to the low concentration of ammonia in deep groundwater aquifers, and hence of TKN, which is sum of Org-N and NH4-N (Table 2). These results are in accordance with Nas and Berktay (2006) who also observed the non-normal distribution of NO3-N in the groundwater of Konya City, Turkey. Table 3 shows the frequency distribution of NO3N (with a step of 10 mg l–1) in the shallow and deep groundwater aquifers. It is evident that in shallow aquifers about 58% samples are situated
Table 1 Basic statistics of the different N-species in the groundwater samples of shallow aquifers (n = 48) of the study region N-Species*
Minimum
Maximum
Mean
SD
Skewness
NO3-N NO2-N NH4-N TKN Org-N Total N
0.10 BDL BDL 7.84 1.39 8.89
64.10 0.48 36.50 45.92 24.90 86.47
14.71 0.09 2.00 13.05 11.05 27.84
16.12 0.14 5.63 5.86 3.60 18.30
1.18 1.70 5.43 21.40 0.79 1.38
*All values are in mg l–1; BDL, below detection limit
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Table 2 Basic statistics of the different N-species in the groundwater samples of deeper aquifers (n = 78) of the study region N-Species*
Minimum
Maximum
Mean
SD
Skewness
NO3-N NO2-N NH4-N TKN Org-N Total N
0.22 BDL BDL 7.84 4.58 9.25
63.80 6.57 39.00 202.16 198.97 219.43
9.57 0.19 1.54 17.31 15.77 27.07
11.93 0.76 5.54 23.46 21.96 28.19
2.30 7.97 5.94 6.94 7.81 4.96
*All values are in mg l–1; BDL, below detection limit
30
b Expected Normal
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Number of Samples
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NO3 -N Classes (mg L ) 45
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Number of Samples
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30 25 20 15 10 5 0
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TKN Classes (mg L )
Fig. 2 Frequency distribution of (a) NO3-N, (b) NO2-N, (c) NH4-N, (d) Org-N, and (e) TKN in shallow aquifers of the study region
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Numberof Samples
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Fig. 3 Frequency distribution of (a) NO3-N, (b) NO2-N, (c) NH4-N, (d) Org-N, and (e) TKN in deep aquifers of the study region
in the [0–10 mg l–1] class, whereas in deep aquifers about 74% samples are situated in this class. Thus, about 42% and 26% groundwater samples in the shallow and deep groundwater aquifers, respectively, exceeded the permissible value of 10 mg l–1 for NO3-N prescribed by Bureau of Indian Standards (BIS, 1992) and Environmental Protection Agency (USEPA, 1996). Costa et al. (2002) have also reported NO3-N concentrations, greater than accepted level (10 mg l–1) for safe drinking water (USEPA, 1996) present in 36% of sampled wells
in the groundwater of the upper Pantanoso Stream Basin (Argentina). Consumption of water having NO3-N concentration higher than 10 mg l–1 may pose serious health hazards. Miao (1989) has reported occurrence of stomach and oesophagus cancers in the Lujiang County, closely correlated with the drinking of shallow waters with high nitrate content. The elevated levels of N-species in the shallow aquifers may be due to the industrial activities going on in the study area. Nitrogen compounds
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Environ Geochem Health (2006) 28:473–485 Class (mg l–1) Shallow aquifers
28 58.33 5 10.42 6 12.50 4 8.33 3 6.25 1 2.08 1 2.08
26.455
Samples (%) Cumulative (%)
57 74.03 10 12.99 5 6.49 3 3.90 1 1.30 0 0.00 1 1.30
74.03 87.01 93.51 97.40 98.70 98.70 100.0
0
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30
b
35
mix with the native groundwater but form a plume. As the pollutants diffuse into the pore spaces of the soil, the dilution is progressive but dispersion increases greatly (Subrahmanyam & Yadaiah, 2001). Kerndorff, Schleyer, Milde, and Plumb (1992), Lee and Jones-Lee (1993), Massing (1994), Mato (1999), Heron, Bjerg, Gravesen, Ludvigsen, and Christensen (1998), Mikac, Cosovic, Ahel, and Toncic (1998) and Riediker, Suter, and Giger (2000), have reported environmental impact of the landfill leakage, particularly on groundwater quality, regardless of an ideal site selection and a monitoring network design. The rate and amount of movement of contaminants in soils and groundwater are generally slow and depend on the properties of the contaminants, the soil, the aquifer, climatological conditions, and 45
0
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a
60
are used extensively in industrial processes such as plastic and metal treatments, raw materials for the textile industry, particleboard/plywood, household cleaning and the pharmaceutical industry (Wakida & Lerner, 2005). In the study area, a large amount of wastewater is discharged without treatment directly/indirectly in to surface water or land from various industries involved in manufacture of wide variety of products (textiles, leather, drugs, chemicals, fertilizers, plastics, cold drinks and edibles etc.). The uncontrolled disposal of waste/wastewater may have negative effects such as pollution of the water table and the soil in the receiving area (Lerner & Tellam, 1992). The leachate from these wastes, combined with precipitation, infiltrates to the shallow water table. The leachates from landfills generally do not
58.33 68.75 81.25 89.58 95.83 97.92 100.00
50
0–10 >10–20 >20–30 >30–40 >40–50 >50–60 >60–70
Samples (%) Cumulative (%) n
55
n
Deep aquifers
40
Table 3 Frequency distribution of the NO3-N in the aquifers of the study region
26.455
26.45 26.45
26.445
26.445 26.44 80.25
80.255
80.26
80.265
80.27
80.245 80.25
80.255 80.26
80.265 80.27
Fig. 4 Spatial distribution of NO3-N concentration (mg l–1) in the (a) shallow aquifers, (b) deep aquifers of the study region
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b 0
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481 0.75
Environ Geochem Health (2006) 28:473–485
26.455 26.455
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b
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Fig. 5 Spatial distribution of NO2-N concentration (mg l ) in the (a) shallow aquifers, (b) deep aquifers of the study region
26.455 26.455
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26.445 26.44 80.25
80.255
80.26
80.265
80.27
80.245
80.25
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80.265
80.27
Fig. 6 Spatial distribution of NH4-N concentration (mg l–1) in the (a) shallow aquifers, (b) deep aquifers of the study region
vegetation patterns (Hornsby, 1999). Singh, Mohan, Sinha, and Dalwani (2004) and Singh, Malik, Singh, and Sinha (2006) studied the impact of treated/untreated wastewater and reported considerable risk and adverse impact on soil,
water, agriculture and human health in the areas (Kanpur and Varanasi, India) receiving the wastewater. In the study area, mainly chemical based industries are operating including one major fertilizer industry manufacturing urea. The
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26.455
NH2 CONH2 þ H2 O ¼ NH2 COONH4 NH2 COONH4 ¼ 2NH3 þ CO2 where NH2COONH4 is ammonium carbamate. The ammonia may be oxidized to nitrite by the bacteria such as Nitrosomonas that can further be oxidized to nitrate by other bacteria such as Nitrobacter. These biologically mediated reactions are collectively referred to as nitrification. Nitrosomonas
þ 2NH3 þ 3O2 ! 2NO 2 þ 2H þ 2H2 O Nitrobacter
2NO 2 þ O2 ! 2NO3
0
10
15
25
b
35
These chemical equations indicate that an oxygen demand is exerted. Further, these interconversions lead to ultimate and higher concentrations of nitrate in the groundwater aquifers. To determine the extent of the contaminant plume, spatial approach was used by mapping the spatial distribution of different N-species. Figures 4–8 present the spatial distribution patterns of the NO3-N, NO2-N, NH4-N, Org-N and TKN in ground water aquifers of the study region. The iso-concentration maps of the all N-species in the
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18
a
20
effluents so produced are generally rich in ammonia and other nitrogen species, which easily may percolate down to sub-soil and groundwater aquifers under natural set of environmental conditions prevailing in the region. The installed (1969–1970) capacity of the fertilizer plant was 675,000 MTPA (metric ton par annum) and the production increased upto 733,000 MT during the year 1998–1999 (http://fert.nic.in/fertcompanies/ dil.asp), however according to the press information bureau (PIB), Government of India (PIB, 2004), the industry is under unscheduled shutdown from 2002. There is an abandoned wastedisposal pond in the study area with no protective bottom lining, earlier used by the nitrogenous fertilizer (Urea) industry for disposal of its effluents with high contents of urea and subsequent recovery through a process of open surface evaporation. Percolation of the wastewater from the disposal sites (waste pond) to the deeper subsoil layers may contaminate the groundwater aquifers. N-species present in the wastewater along with the urea moves with the percolating water. Urea (NH2CONH2) hydrolyzes slowly to ammonium carbamate and eventually decomposes to ammonia and carbon dioxide.
26.455
26.45 26.45
26.445
26.445 26.44 80.25
80.255
80.26
80.265
80.27
80.245
80.25 80.255
80.26
80.265
80.27
Fig. 7 Spatial distribution of Org-N concentration (mg l–1) in the (a) shallow aquifers, (b) deep aquifers of the study region
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180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0
a
483
44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6
Environ Geochem Health (2006) 28:473–485
b
26.455
26.45 26.45
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26.445 26.44 80.25
80.255
80.26
80.265
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80.245 80.25
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–1
Fig. 8 Spatial distribution of TKN concentration (mg l ) in the (a) shallow aquifers, (b) deep aquifers of the study region
shallow aquifers show almost similar patterns indicating the diffusion of plumes from north to the south direction. This may be due to the influence of the fresh water canal flowing through the study area as the drainage pattern of the study region is from NW to SE. Further, the region of high concentration of these species coincides and spatial distribution has almost the same characteristics in the shallow aquifers, whereas in deep aquifers the plumes of N-species originate in the East-Southern part of the study area. The difference in the distribution pattern of nitrogenous species in shallow and deep aquifers may be due to more complex processes involved in interactions at solid–water interface in the deeper aquifers. Moreover, the origin of the plume of N-species in the shallow aquifers coincides with the waste pond located in the study area and earlier used by the fertilizer industry indicating possibility of the groundwater contamination with the leaching/movement of contaminants from the soil surface to the underneath groundwater. Conclusions The results of the study reveal that the aquifers of the Kanpur city are highly contaminated with the
nitrate, which may cause serious health hazards to the population of the area. The spatial distribution of the concentrations of the N-species suggests point source of the nitrate pollution in the aquifer. In the groundwater aquifers of the study area, the main source of nitrate contamination is wastewater disposal from industrial activities. A large amount of samples from the shallow and deeper aquifers exceeding the standard limit (10 mg l–1) of nitrate indicates high risk for the people of the study area consuming the water, as the groundwater is the main drinking water source in the region. Further, the findings suggest for a thorough health monitoring in the region for any adverse effects and provision for safe drinking water. Acknowledgements We thank the Director, Industrial Toxicology Research Centre, Lucknow for his consistent support and interest in this work and CSIR (New Delhi) for financial assistance under COR-0005 project.
References Albaiges, J., Casado, F., & Ventura, F. (1986). Organic indicators of groundwater pollution by a sanitary landfill. Water Research, 20, 1153–1159. APHA (1998). Standard methods for the examination of water and wastewater, 18th ed. Washington, DC: American Public Health Association.
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484 Babiker, I. S., Mohamed, M. A. A., Terao, H., Kato, K., & Ohta, K. (2004). Assessment of ground water contamination by nitrate leaching from intensive vegetable cultivation using geographical information system. Environment International, 29, 1009–1017. Benefield, L. D., Judikins, J. F., & Weand, B. L. (1982). Process chemistry for water and wastewater treatment. Englewood Cliffs, New Jersey: Prentice Hall Inc., p. 449. Binotto, R. B., Teixeira, E. C., Sanchez, J. C. D., Migliavacca, D., & Nanni, A. S. (2000). Environmental assessment: Contamination of phreatic aquifer in areas impacted by waste from coal processing activities. Fuel, 79, 1547–1560. BIS (1992). Bureau of Indian Standards. IS:10500. Manak Bhawan, New Delhi, India. Census (2001). Census of India: final population total. Registrar General & Census Commissioner, India, Ministry of Home Affairs, New Delhi. Chan, T. Y. K. (1996). Food borne nitrates and nitrites as a case of methaemoglobinemia. Southeast Asian Journal of Tropical Public Health, 27, 189–192. Costa, J. L., Massone, H., Martinez, D., Suero, E. E., Vidal, C. M., & Bedmar, F. (2002). Nitrate contamination of a rural aquifer and accumulation in the unsaturated zone. Agricultural Water Management, 57, 33–47. Datta , P. S., Deb, D. L., & Tyagi, S. K. (1997). Assessment of groundwater contamination from fertilizers in the Delhi area based on 18O, NO–3 and K+ composition. Journal of Contaminant Hydrology, 27, 249–262. Fennesy, M. S., & Cronk, J. K. (1997). The effectiveness and restoration potential of riparian ecotones for the management of nonpoint source pollution, particularly nitrate. Critical Reviews in Environmental Science and Technology, 27, 285–317. Flyammar, P. (1995). Leachate quality and environmental effects at active Swedish municipal landfill. In: R. Cossu, H. T. Christensen, & R. Stegmann (eds.), Regulations, environmental impact and aftercare. Proceedings Sardinia 95, Fifth International Landfill Symposium, Vol III. Sardinia, Italy, 557 pp. Heron, G., Bjerg, P. L., Gravesen, P., Ludvigsen, L., & Christensen, T. H. (1998). Geology and sediment geochemistry of a landfill leachate contaminated aquifer (Grinsted, Denmark). Journal of Contaminant Hydrology, 29, 301–317. Hornsby, A. G. (1999). How contaminants reach groundwater. SL143, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Kerndorff, H., Schleyer, R., Milde, G., & Plumb, R. H. (1992). Geochemistry of groundwater pollutants at German waste disposal sites. In: S. Lesage, & R. E. Jackson (eds.), Groundwater contamination and analysis at hazardous waste sites (pp. 245–272). New York: Marcel Dekker. Killpack, S. C., & Buchhalz, D. (1993). Nitrogen in the environment: how nitrogen enters groundwater. WQ256. Department of Agronomy, Uni Missouri Extension. Laftouhi, N., Vanclooster, M., & Jalal, M. (2003). Groundwater nitrate pollution in the Essaouira Basin (Morocco). CR Geosciences, 335, 307–317.
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Environ Geochem Health (2006) 28:473–485 Lee, G. F., & Jones-Lee, A. (1993). A groundwater protection strategy for lined landfills. Environmental Science and Technology, 28, 584A–585A. Lee, S. M., Min, K. D., Woo, N. C., Kim, Y. J., & Ahn, C. H. (2003). Statistical models for the assessment of nitrate contamination in urban groundwater using GIS. Environmental Geology, 44, 210–221. Lerner, D. N., & Tellam, J. H. (1992). The protection of urban groundwater from pollution. Water and Environment Management, 6, 28–37. Massing, H. (1994). Impacts of leakage from urban solid waste deposits on groundwater quality. Water Science and Technology, 29, 239–244. Mato, R. R. A. M. (1999). Environmental implications involving the establishment of sanitary landfills in five municipalities in Tanzania: the case of Tanga municipality, Roirces. Journal of Conservation and Recycling, 25, 1–16. Mikac, N., Cosovic, B., Ahel, S. A., & Toncic, Z. (1998). Assessment of groundwater contamination in the vicinity of a municipal waste landfill (Zagreb, Croatia). Water Sciences Technology, 37, 37–44. Miao, Y. D. (1989). Relationship between drinking water types and dead rate of tumor. Tumor, 9, 8–10. Namade, P. N., & Srivastava, N. S. (1997). Nitrate (NO3N) status of groundwater in Tribal belt of Satpura Valley. Indian Journal of Environmental Protection, 17, 430–433. Nas, B., & Berktay, A. (2006). Groundwater contamination by nitrates in the city of Konya, (Turkey): a GIS perspective. Journal of Environmental Management, 79, 30–37. Pandey, D. S., & Mukherjee, S. (1994a). Nitrate contamination in groundwater in Varanasi city and its environs, Uttar Pradesh, India. In Groundwater Monitoring and Management (Proc. Intern. Dresden Symp.), pp. 1–14. Pandey, D. S., & Mukherjee, S. (1994b). Nitrate pollution: an alarming problem in and around Jaunpur, Uttar Pradesh, India: a case study. In Environmental Aspects of Groundwater Development (Regional Workshop, Kurukshetra, India, Oct. 17–19, 1994), I-147-I152. PIB (2004). Press Information Bureau, Govt. of India. Press Releases, June 21, 2004. Reid, D. C., Edwards, A. C., Cooper, D., Wilson, E., & Mcgwaw, B. A. (2003). The quality of drinking water from private water supplies in Aberdeenshire, UK. Water Research, 37, 245–254. Richard, Y. (1980). Denitrification of water for human consumption. Progress in Water Technology, 12, 173. Riediker, S., Suter, J. F. M., & Giger, W. (2000). Benzene and naphthalenesulfonates in leachates and plumes of landfills. Water Resources, 34, 2069–2079. Rukah, Y. A., & Alsokhny, K. (2004). Geochemical assessment of groundwater contamination with special emphasis on fluoride concentration, North Jordan. Chemie der Erde, 64, 171–181. Shrimali, M., & Singh, K. P. (2001). New methods of nitrate removal from water. Environmental Pollution, 112, 351–359.
Environ Geochem Health (2006) 28:473–485 Singh, K. P., Malik, A., Singh, V. K., & Sinha, S. (2006). Multi-way data analysis of soils irrigated with wastewater – a case study. Chemometrics and Intelligent Laboratory Systems (in press). Singh, K. P., Mohan, D., Sinha, S., & Dalwani, R. (2004). Impact assessment of treated/untreated wastewater toxicants discharged by sewage treatment plants on health, agricultural, and environmental quality in the wastewater disposal area. Chemosphere, 55, 227–255. Subrahmanyam, K., & Yadaiah, P. (2001). Assessment of the impact of industrial effluents on water quality in Patancheru and environs, Medak district, Andhra Pradesh, India. Hydrogeology Journal, 9, 297–312. Sylvestre, S., Brewer, R., Sekela, M., Tuominen, T., & Moyle, G. (1998). Survey of contaminants in Fraser
485 river suspended sediment and water upstream and downstream of Annacis Island wastewater treatment plant (1996). Aquatic and Atmospheric Sciences Division, Environmental Conservation Branch, Pacific and Yukon Region, Environment Canada, DOE FRAP 1997-35. USEPA (1996). Water Environmental Indicators #11, EPA Office of the Water, June 1996. Wakida, F. T., & Lerner, D. N. (2005). Non-agricultural sources of groundwater nitrate: a review and case study. Water Research, 39, 3–16. Zingoni, E., Love, D., Magadza, C., Moyce, W., & Musiwa, K. (2005). Effects of a semi-formal urban settlement on groundwater quality Epworth (Zimbabve): case study and groundwater quality zoning. Physics and Chemistry of the Earth, 30, 680–688.
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ORIGINAL PAPER
Distribution of nitrogen species in groundwater aquifers of an industrial area in alluvial Indo-Gangetic Plains—a case study Kunwar P. Singh Æ Vinod K. Singh Æ Amrita Malik Æ Nikita Basant
Received: 20 September 2005 / Accepted: 10 May 2006 / Published online: 22 June 2006 Springer Science+Business Media B.V. 2006
Abstract The groundwater samples collected from the shallow and deep groundwater aquifers of an industrial area of the Kanpur city (Uttar Pradesh, India) were analyzed for the concentration levels and distribution pattern of nitrogenous species, such as nitrate-nitrogen (NO3-N), nitrite-nitrogen (NO2-N), ammonical-nitrogen (NH4-N), organic-nitrogen (Org-N) and total Kjeldahl-nitrogen (TKN) to identify the possible contamination source. Geo-statistical approach was adopted to determine the distribution and extent of the contaminant plume. In the groundwater aquifers NO3-N, NO2-N, NH4-N, TKN, Org-N and Total-N ranged from 0.10 to 64.10, BDL (below detection limit)-6.57, BDL-39.00, 7.84–202.16, 1.39–198.97 and 8.89–219.43 mg l–1, respectively. About 42% and 26% of the groundwater samples of the shallow and deep groundwater aquifers, respectively, exceeded the BIS (Bureau of Indian Standards) guideline value of 10 mg l–1 for NO3-N and may pose serious health hazards to the people of the area. The results of the study revealed that the groundwater K. P. Singh (&) Æ V. K. Singh Æ Amrita Malik Environmental Chemistry Section, Industrial Toxicology Research Centre, Post Box 80, MG Marg, Lucknow 226 001, India e-mail: [email protected] N. Basant AAI-DU, Allahabad, India
aquifers of the study area are highly contaminated with the nitrate and indicates point source pollution of nitrate in the study area. Keywords Industrial area Æ Contamination Æ Nitrate pollution Æ Point source Æ Fertilizer industry
Introduction Nitrate is found in most of the natural waters at moderate concentrations but is often enriched to the contaminant level in the groundwater resources mainly from the excessive use of fertilizers and uncontrolled on-land discharge of raw and treated wastewater (Shrimali & Singh, 2001). Nitrogen chemistry is complicated by the multiplicity of oxidation states, the element assumes in its compounds. Nitrate (NO3), nitrite (NO2), ammonia (NH3), and organically bound forms of nitrogen (Org-N) are the species of interest for water resource management. Various forms of nitrogen (oxidized and reduced) are present in many possible recharge sources of urban aquifers. Nitrate contamination of the groundwater in different parts of India and other regions of the world has been reported (Datta, Deb, & Tyagi, 1997; Laftouhi, Vanclooster, & Jalal, 2003; Namade & Srivastava, 1997; Pandey & Mukherjee, 1994a, b; Reid, Edwards, Cooper, Wilson, &
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Mcgraw, 2003; Wakida & Lerner, 2005). Nitrate has been linked to agricultural activities due to the use of nitrogenous fertilizers. The non-agricultural sources include leakage from water supply and disposal networks, on-site sewage disposal, animal waste, contaminated land, industry, river and aquifer interaction, atmospheric deposition, urban fertilizer use, storm water, house building, and direct recharge (Wakida & Lerner, 2005). Among these industries are the potential sources of nitrogen to the groundwater. Nitrogen compounds are used extensively in the industrial processes such as plastic and metal treatments, raw materials for the textile industry, particle board and plywood, household cleaning, fertilizers and the pharmaceutical industry. Contaminated lands such as abandoned landfills, gasworks site or abandoned industrial sites contribute a significant quantity of nitrogen to groundwater. Landfills are considered a major source of pollutants and their impacts on groundwater quality have been reported (Albaiges, Casado, & Ventura, 1986; Flyammar, 1995). In developing countries landfills are usually open dumping sites for disposal of domestic/industrial wastes. Pollutants from these sites may percolate down to sub-soil and groundwater aquifers under natural set of environmental conditions prevailing in the region. Groundwater and surface water contamination with nitrogenous species can cause health problems in infants and animals as well as the eutrophication of water bodies (Fennesy & Cronk, 1997). Nitrate ion has been identified as a potential health hazard to infants and pregnant woman (Chan, 1996). The nitrate ion is responsible for the disease ‘methaemoglobinemia’ or ‘blue-baby syndrome’ (Benefield, Judikins, & Weand, 1982). Under certain conditions, nitrate can be converted into much more poisonous nitrite and even to a carcinogenic nitrosamine (Richard, 1980) which primarily affects the oesophagus and pharynx (gastrointestinal tract). Groundwater constitutes major source of water for domestic, drinking, and industrial purposes in Kanpur city, which is one of the important industrial centers in northern India. There are more than 800 industries in the city involved in manufacture of wide variety of products such as textiles, leather, drugs, chemicals, fertilizers,
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plastics, cold drinks and edibles, etc. Out of the total drinking water demand of about 500 million l per day (mld), more than half is met by the groundwater sources, whereas, for the industrial purposes, water requirements are mainly met through groundwater sources. Subsequently, a huge amount of domestic and industrial wastewater is generated. The current total capacity of wastewater treatment plants in the city is about 142 mld. Panki, Dada Nagar, Armapur and Jajmau are the established industrial areas within the city. In Panki industrial area, mainly chemical based industries are operating including one major fertilizer industry manufacturing urea. The effluents so produced are generally rich in ammonia and other nitrogen species and there are the possibilities for the contamination of groundwater aquifers with the nitrogen-species. The rivers, streams and ponds are among the main surface water sources in the region, while the dug well, tube well, bore well and hand-pump constitute the groundwater sources. The groundwater in the study region occurs mostly at shallow depth aquifers with water level depth of less than 10 m below the ground level. This study focuses on the concentration levels and distribution of various nitrogen species in groundwater aquifers of Kanpur City, with an attempt to identify the source of contamination and delineate its boundaries for remedial purpose to safeguard the public health, as groundwater is the major source of domestic, drinking, and industrial water supplies in Kanpur city.
Materials and methods Study area Kanpur, the eighth largest city of India, is an industrial town located (latitude N 2620¢ and 2635¢ and longitude E 8010¢ and 8030¢) in the Central Alluvial Ganga Plain (Fig. 1). It encompasses an area of about 1040 km2 with a population of more than 2.53 million (Census, 2001). The present study is confined to the Panki industrial area. In the study region, a three-tier aquifer system viz., shallow, middle and deep aquifers, exists
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Fig. 1 Map of the study area showing sampling locations
down to bedrock and the aquifers are connected through the clay beds. Shallow aquifers, consisting of very fine-to-fine sand, occur down to 150 m
bgl (below ground level). Middle aquifers, consisting of fine to medium sand, occur between 150 m and 250 m and deep aquifers occurring
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between the depths of 250 m and 400 m bgl consist of medium to coarse sand and gravel. The groundwater in the deeper aquifers occur under confined and semi-confined conditions, whereas, near surface groundwater in the phreatic zone (thickness about 50 m bgl) is unconfined and is tapped by shallow hand pumps and dug wells. The groundwater in the investigated area originates from a combination of rainfall, river/canal water and irrigation water flow. Ground water in the deeper aquifers is mostly recharged through leakage from the upper unconfined aquifer and partly from lateral groundwater flow from the north and north-east.
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of nitrate and nitrite, respectively. Ammonia (NH4-N) was determined spectrophotometrically (nesslerization method) using UV–VIS spectrophotometer (GBC Cintra-40, Australia), whereas total Kjeldahl-nitrogen (TKN) was determined by distillation (Macro-Kjeldhal Method) and titration with H2SO4 (APHA, 1998). TKN is the sum of free ammonia and organic nitrogen compounds. Organic nitrogen (Org-N) was estimated from the difference of TKN and NH4-N in each sample. The total nitrogen (Total-N) is the sum of all nitrogen forms as above. The minimum detection limits for nitrate, nitrite, ammonia and TKN were 0.1, 0.05, 0.02 and 0.2 mg l–1, respectively.
Sample collection and analysis Quality assurance A total of 126 groundwater samples were collected in December 2004 from the Panki Industrial region in Kanpur City (Fig. 1). The study region covering an area of about 6 km2 is demarcated by hydrological boundaries, a fresh water canal in north and Pandu River in south. Samples were collected from the hand-pumps and bore wells spread over the entire study region. Samples from tube wells, bore wells and handpumps were collected from the outlets after flushing water for 10–15 min in order to remove the stagnant water. The water samples were collected in high quality air-tight polyethylene containers. The sample containers were thoroughly cleaned and pre-washed with phosphate free detergent and rinsed with distilled water (Sylvestre, Brewer, Sekela, Tuominen, & Moyle, 1998). The collected water samples were immediately transported to the laboratory in ice boxes under low temperature (4C) conditions and processed immediately for analysis (APHA, 1998). The samples were stored in deep freezer at 4C and the analysis was completed within 24 h. Nitrate (NO3-N) and nitrite (NO2-N) ions were measured by ion-selective electrode method using ionplus combination electrodes: ORION 97-07 NO–3 ion electrode for nitrate and ORION 97-46 NO–2 ion electrode for nitrite equipped with an Ion meter (model 960A, ThermoOrion, USA). Nitrate interference suppressor solution (Orion 930710) and nitrite interference suppressor solution (Orion 934610) were used for determination
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The analytical data quality was ensured through careful standardization, procedural blank measurements, and spiked and duplicate samples. The laboratory also participates in regular national program on analytical quality control (AQC). For NO2-N, NO3-N and NH4-N synthetic solutions in the concentration range of 0.1–100 mg l–1, 0.1– 50 mg l–1, and 0.1–5.0 mg l–1, respectively were prepared separately through spiking of deionized water (DI) with their respective standards (Merck, India). For TKN, glutamic acid (99%, SRL, India) was used as standard for Org-N and spiked solutions (0–5.0 mg-N l–1) in DI water were prepared. Recoveries of the N-species from the spiked water samples (n = 10) were found to be between 94 to 102%. After each batch of 10 samples, series of these spiked solutions were analyzed following the same procedures along with their respective blanks. In all the analysis, blanks were run and corrections were applied, if necessary. All the observations were recorded in duplicate and average values are reported. Appropriate dilutions were applied wherever necessary.
Results and discussions In general, in the groundwater samples collected over the entire study region (shallow and deep aquifers) the NO3-N, NO2-N, NH4-N, TKN,
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Org-N and Total-N ranged from 0.1 to 64.1, BDL6.6, BDL-39.0, 7.8–202.2, 1.4–198.9 and 8.9– 219.4 mg l–1, respectively. In study area the levels of NO3-N were higher then that observed in the groundwater of south Brazil impacted with waste from coal processing activities (NO3-N, 0.40– 3.40 mg l–1; Binotto, Teixeira, Sanchez, Migliavacca, & Nanni, 2000), in the groundwater of Epworth (NO3-N, 0.0–6.74 mg l–1; Zingoni, Love, Magadza, Moyce, & Musiwa, 2005) and in the groundwater of Kakamigahara Heights, Central Japan (NO3-N, 0.49–26.61 mg l1; Babiker, Mohamed, Terao, Kato, & Ohta, 2004). However, levels of NO3-N in study area were lower than reported by Nas and Berktay (2006) in the groundwater of Konya City, Turkey (3.0– 110.0 mg l–1 in the year 2001). Rukah and Alsokhny (2004) have also observed enhanced nitrate concentrations (7.57–90.23 mg l–1) in the groundwater of North Jordan. They attributed this to the discharge of sewage effluents, fertilizers, animal excreta, rainfall and industrial effluents to unsaturated aquifers. The basic statistics of the nitrogen species (N-species) detected in the groundwater samples from the shallow and deeper aquifers of the studied region is given in Tables 1 and 2, respectively. There was observed a wide spatial variation in the levels of different N-species viz. NO3-N, NO2-N, NH4-N, TKN, Org-N and Total-N determined in the groundwater samples collected from the study region. It was also observed that mean concentration level of NO3-N (14.7 mg l–1) and NH4-N (2.0 mg l–1) in shallow aquifers were relatively higher than that observed in the deeper aquifers (NO3-N, 9.6 mg l–1; NH4-N, 1.54 mg l–1). Further, the mean concentration levels of NO3-N were higher
than that of NH4-N and NO2-N in both the shallow as well as deeper aquifers. Lee, Min, Woo, Kim, and Ahn (2003) have also reported higher concentrations of NO3-N in shallow wells as compared to the deep wells in the groundwater of Seoul (Korea). This may be attributed to the fact that nitrate, as compared to other nitrogen species, does not attach to soil particles and is easily moved to groundwater. In addition, if depth to groundwater is shallow and the underlying soil is sandy, as in the study region, the potential for nitrates to enter groundwater is relatively high (Killpack & Buchhalz, 1993). Moreover, the extra-ordinary aqueous solubility of nitrates imparts higher mobility to the ion with the groundwater flow. Figures 2 and 3 present the histograms for the frequency distribution of various N-species (NO3-N, NO2-N, NH4-N, Org-N, and TKN) in groundwater aquifers suggesting skewed (non-normal) distribution in both the shallow (Fig. 2) and deep (Fig. 3) aquifers. The skewed frequency distribution of the N-species suggests groundwater contamination from both point and non-point sources of pollution. The distribution of Org-N and TKN showed almost similar trends in the deep groundwater aquifers (Fig. 3d and e, respectively). This may be due to the low concentration of ammonia in deep groundwater aquifers, and hence of TKN, which is sum of Org-N and NH4-N (Table 2). These results are in accordance with Nas and Berktay (2006) who also observed the non-normal distribution of NO3-N in the groundwater of Konya City, Turkey. Table 3 shows the frequency distribution of NO3N (with a step of 10 mg l–1) in the shallow and deep groundwater aquifers. It is evident that in shallow aquifers about 58% samples are situated
Table 1 Basic statistics of the different N-species in the groundwater samples of shallow aquifers (n = 48) of the study region N-Species*
Minimum
Maximum
Mean
SD
Skewness
NO3-N NO2-N NH4-N TKN Org-N Total N
0.10 BDL BDL 7.84 1.39 8.89
64.10 0.48 36.50 45.92 24.90 86.47
14.71 0.09 2.00 13.05 11.05 27.84
16.12 0.14 5.63 5.86 3.60 18.30
1.18 1.70 5.43 21.40 0.79 1.38
*All values are in mg l–1; BDL, below detection limit
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Table 2 Basic statistics of the different N-species in the groundwater samples of deeper aquifers (n = 78) of the study region N-Species*
Minimum
Maximum
Mean
SD
Skewness
NO3-N NO2-N NH4-N TKN Org-N Total N
0.22 BDL BDL 7.84 4.58 9.25
63.80 6.57 39.00 202.16 198.97 219.43
9.57 0.19 1.54 17.31 15.77 27.07
11.93 0.76 5.54 23.46 21.96 28.19
2.30 7.97 5.94 6.94 7.81 4.96
*All values are in mg l–1; BDL, below detection limit
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Fig. 2 Frequency distribution of (a) NO3-N, (b) NO2-N, (c) NH4-N, (d) Org-N, and (e) TKN in shallow aquifers of the study region
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Fig. 3 Frequency distribution of (a) NO3-N, (b) NO2-N, (c) NH4-N, (d) Org-N, and (e) TKN in deep aquifers of the study region
in the [0–10 mg l–1] class, whereas in deep aquifers about 74% samples are situated in this class. Thus, about 42% and 26% groundwater samples in the shallow and deep groundwater aquifers, respectively, exceeded the permissible value of 10 mg l–1 for NO3-N prescribed by Bureau of Indian Standards (BIS, 1992) and Environmental Protection Agency (USEPA, 1996). Costa et al. (2002) have also reported NO3-N concentrations, greater than accepted level (10 mg l–1) for safe drinking water (USEPA, 1996) present in 36% of sampled wells
in the groundwater of the upper Pantanoso Stream Basin (Argentina). Consumption of water having NO3-N concentration higher than 10 mg l–1 may pose serious health hazards. Miao (1989) has reported occurrence of stomach and oesophagus cancers in the Lujiang County, closely correlated with the drinking of shallow waters with high nitrate content. The elevated levels of N-species in the shallow aquifers may be due to the industrial activities going on in the study area. Nitrogen compounds
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28 58.33 5 10.42 6 12.50 4 8.33 3 6.25 1 2.08 1 2.08
26.455
Samples (%) Cumulative (%)
57 74.03 10 12.99 5 6.49 3 3.90 1 1.30 0 0.00 1 1.30
74.03 87.01 93.51 97.40 98.70 98.70 100.0
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mix with the native groundwater but form a plume. As the pollutants diffuse into the pore spaces of the soil, the dilution is progressive but dispersion increases greatly (Subrahmanyam & Yadaiah, 2001). Kerndorff, Schleyer, Milde, and Plumb (1992), Lee and Jones-Lee (1993), Massing (1994), Mato (1999), Heron, Bjerg, Gravesen, Ludvigsen, and Christensen (1998), Mikac, Cosovic, Ahel, and Toncic (1998) and Riediker, Suter, and Giger (2000), have reported environmental impact of the landfill leakage, particularly on groundwater quality, regardless of an ideal site selection and a monitoring network design. The rate and amount of movement of contaminants in soils and groundwater are generally slow and depend on the properties of the contaminants, the soil, the aquifer, climatological conditions, and 45
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are used extensively in industrial processes such as plastic and metal treatments, raw materials for the textile industry, particleboard/plywood, household cleaning and the pharmaceutical industry (Wakida & Lerner, 2005). In the study area, a large amount of wastewater is discharged without treatment directly/indirectly in to surface water or land from various industries involved in manufacture of wide variety of products (textiles, leather, drugs, chemicals, fertilizers, plastics, cold drinks and edibles etc.). The uncontrolled disposal of waste/wastewater may have negative effects such as pollution of the water table and the soil in the receiving area (Lerner & Tellam, 1992). The leachate from these wastes, combined with precipitation, infiltrates to the shallow water table. The leachates from landfills generally do not
58.33 68.75 81.25 89.58 95.83 97.92 100.00
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Samples (%) Cumulative (%) n
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Table 3 Frequency distribution of the NO3-N in the aquifers of the study region
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Fig. 4 Spatial distribution of NO3-N concentration (mg l–1) in the (a) shallow aquifers, (b) deep aquifers of the study region
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34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
a
15
Fig. 5 Spatial distribution of NO2-N concentration (mg l ) in the (a) shallow aquifers, (b) deep aquifers of the study region
26.455 26.455
26.45 26.45
26.445
26.445 26.44 80.25
80.255
80.26
80.265
80.27
80.245
80.25
80.255
80.26
80.265
80.27
Fig. 6 Spatial distribution of NH4-N concentration (mg l–1) in the (a) shallow aquifers, (b) deep aquifers of the study region
vegetation patterns (Hornsby, 1999). Singh, Mohan, Sinha, and Dalwani (2004) and Singh, Malik, Singh, and Sinha (2006) studied the impact of treated/untreated wastewater and reported considerable risk and adverse impact on soil,
water, agriculture and human health in the areas (Kanpur and Varanasi, India) receiving the wastewater. In the study area, mainly chemical based industries are operating including one major fertilizer industry manufacturing urea. The
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Environ Geochem Health (2006) 28:473–485
26.455
NH2 CONH2 þ H2 O ¼ NH2 COONH4 NH2 COONH4 ¼ 2NH3 þ CO2 where NH2COONH4 is ammonium carbamate. The ammonia may be oxidized to nitrite by the bacteria such as Nitrosomonas that can further be oxidized to nitrate by other bacteria such as Nitrobacter. These biologically mediated reactions are collectively referred to as nitrification. Nitrosomonas
þ 2NH3 þ 3O2 ! 2NO 2 þ 2H þ 2H2 O Nitrobacter
2NO 2 þ O2 ! 2NO3
0
10
15
25
b
35
These chemical equations indicate that an oxygen demand is exerted. Further, these interconversions lead to ultimate and higher concentrations of nitrate in the groundwater aquifers. To determine the extent of the contaminant plume, spatial approach was used by mapping the spatial distribution of different N-species. Figures 4–8 present the spatial distribution patterns of the NO3-N, NO2-N, NH4-N, Org-N and TKN in ground water aquifers of the study region. The iso-concentration maps of the all N-species in the
45
0
2
4
6
8
10
12
14
16
18
a
20
effluents so produced are generally rich in ammonia and other nitrogen species, which easily may percolate down to sub-soil and groundwater aquifers under natural set of environmental conditions prevailing in the region. The installed (1969–1970) capacity of the fertilizer plant was 675,000 MTPA (metric ton par annum) and the production increased upto 733,000 MT during the year 1998–1999 (http://fert.nic.in/fertcompanies/ dil.asp), however according to the press information bureau (PIB), Government of India (PIB, 2004), the industry is under unscheduled shutdown from 2002. There is an abandoned wastedisposal pond in the study area with no protective bottom lining, earlier used by the nitrogenous fertilizer (Urea) industry for disposal of its effluents with high contents of urea and subsequent recovery through a process of open surface evaporation. Percolation of the wastewater from the disposal sites (waste pond) to the deeper subsoil layers may contaminate the groundwater aquifers. N-species present in the wastewater along with the urea moves with the percolating water. Urea (NH2CONH2) hydrolyzes slowly to ammonium carbamate and eventually decomposes to ammonia and carbon dioxide.
26.455
26.45 26.45
26.445
26.445 26.44 80.25
80.255
80.26
80.265
80.27
80.245
80.25 80.255
80.26
80.265
80.27
Fig. 7 Spatial distribution of Org-N concentration (mg l–1) in the (a) shallow aquifers, (b) deep aquifers of the study region
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26.455
180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0
a
483
44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6
Environ Geochem Health (2006) 28:473–485
b
26.455
26.45 26.45
26.445
26.445 26.44 80.25
80.255
80.26
80.265
80.27
80.245 80.25
80.255
80.26
80.265
80.27
–1
Fig. 8 Spatial distribution of TKN concentration (mg l ) in the (a) shallow aquifers, (b) deep aquifers of the study region
shallow aquifers show almost similar patterns indicating the diffusion of plumes from north to the south direction. This may be due to the influence of the fresh water canal flowing through the study area as the drainage pattern of the study region is from NW to SE. Further, the region of high concentration of these species coincides and spatial distribution has almost the same characteristics in the shallow aquifers, whereas in deep aquifers the plumes of N-species originate in the East-Southern part of the study area. The difference in the distribution pattern of nitrogenous species in shallow and deep aquifers may be due to more complex processes involved in interactions at solid–water interface in the deeper aquifers. Moreover, the origin of the plume of N-species in the shallow aquifers coincides with the waste pond located in the study area and earlier used by the fertilizer industry indicating possibility of the groundwater contamination with the leaching/movement of contaminants from the soil surface to the underneath groundwater. Conclusions The results of the study reveal that the aquifers of the Kanpur city are highly contaminated with the
nitrate, which may cause serious health hazards to the population of the area. The spatial distribution of the concentrations of the N-species suggests point source of the nitrate pollution in the aquifer. In the groundwater aquifers of the study area, the main source of nitrate contamination is wastewater disposal from industrial activities. A large amount of samples from the shallow and deeper aquifers exceeding the standard limit (10 mg l–1) of nitrate indicates high risk for the people of the study area consuming the water, as the groundwater is the main drinking water source in the region. Further, the findings suggest for a thorough health monitoring in the region for any adverse effects and provision for safe drinking water. Acknowledgements We thank the Director, Industrial Toxicology Research Centre, Lucknow for his consistent support and interest in this work and CSIR (New Delhi) for financial assistance under COR-0005 project.
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