Nitrate concentrations were measured in the groundwater samples of Krishna delta, India. The results indicate a large variation of nitrate from 10 - 135 mg/l. In 79 groundwater samples, about 39% shows high nitrate contents (&gt;50 mg/l), which is more than the permissible limits in drinking water. In north Krishna delta 49% and in south Krishna delta 26% water samples were found to exceed the permissible limits. This study indicates that groundwater of north Krishna delta is more polluted than south. Nitrate pollution level is found more in dug wells compared to hand pumps/bore wells. In this region 49% dug wells and 31% hand pumps have exceeded the desirable limits. The possible sources for the high nitrate level in groundwater were identified as excessive utilization of nitrogenous fertilizers for agricultural purposes.Key words: Nitrate pollution, groundwater, Krishna delta, India

Mondal, N.C.

Saxena, V.K.

Singh, V.S.

English

AJOL - African Journals Online

African Journal of Environmental Science and Technology Vol. 2 (9).  pp. 265-271, September, 2008 Available online at http://www.academicjournals.org/AJest ISSN 1996-0786 © 2008 Academic Journals      Full Length Research Paper  Occurrence of elevated nitrate in groundwaters of Krishna delta, India  N. C.  Mondal*, V. K. Saxena and V. S. Singh  National Geophysical Research Institute (Council of Scientific and Industrial Research), Uppal Road, Hyderabad-500 606, India  Accepted 28 August, 2008  Nitrate concentrations were measured in the groundwater samples of Krishna delta, India. The results indicate a large variation of nitrate from 10 - 135 mg/l. In 79 groundwater samples, about 39% shows high nitrate contents (>50 mg/l), which is more than the permissible limits in drinking water. In north Krishna delta 49% and in south Krishna delta 26% water samples were found to exceed the permissible limits. This study indicates that groundwater of north Krishna delta is more polluted than south. Nitrate pollution level is found more in dug wells compared to hand pumps/bore wells. In this region 49% dug wells and 31% hand pumps have exceeded the desirable limits. The possible sources for the high nitrate level in groundwater were identified as excessive utilization of nitrogenous fertilizers for agricultural purposes.  Key words: Nitrate pollution, groundwater, Krishna delta, India.  INTRODUCTION   The presence of high nitrate concentration (>50 mg/l) in groundwater would normally indicate pollution of groundwater. The World Health Organization (WHO, 1993) standard was originally set at 45 mg/l nitrate has been adjusted to 50 mg/l (Chettri and Smith, 1995; Canter, 1997). Since presence of excess nitrate ions in groundwater is harmful to health, their occurrence in high concentrations in groundwater is a matter of great concern. The leaching of nitrates from agriculture land has been a major research focus in past two decades. It is well-known that inorganic nitrogen fertilizers, septic tanks, poor dug wells and defective sewerage systems are the suspected major sources of nitrate in groundwater systems (Piskin, 1973; Canter, 1997, Lindsay, 1997).    It is well established, if nitrates are consumed more than the permissible limit (> 50 mg/l), it may lead to several types of diseases (Reddy, 1981; Dudley, 1990). Chemically during nitrate-water reaction, the nitrates are converted into nitrites and such reactions take place in the digestive system of human body. The nitrates oxidize     *Corresponding author. E-mail:ncmngri@yahoo.co.in.  Tel: +91-40-23434700(2608). Fax: +91-40-23434651. the hemoglobin to met-hemoglobin and cause for several types of disease, which mostly depend on duration and quantity of nitrite consumption (Perlistein and Attala, 1976; Dudley, 1990). The Met-hemoglobin is a pigment, which is incapable of acting as oxygen carrier in blood vessels. The consumption of nitrate rich water cause a large number of diseases like dizziness, abdominal disorder, vomiting, weaknesses, high rate of pulptation, mental disorder and even stomach cancer etc. (Perlistein and Attala, 1976; Reddy, 1981; Thind, 1982; Burt et al., 1993). The study area lies within the Krishna delta, which is very fertile for the agricultural point of view. The sand plain aquifers are the main source of water for agriculture and domestic purposes. The deltaic aquifers are recharged by direct infiltration of precipitation. Dug wells, bore wells and hand pumps are the major drinking water source in this delta. As a part of research and development activity in the delta particularly for the assessment of groundwater quality, 79 groundwater samples were collected and analysised. The purpose of this work is to determine the extent of nitrate in groundwater in selected regions of north and south Krishna delta and to study the possible source of nitrate pollutants and suggest possible measures for the pro-tection of groundwater quality in the delta. 266      Afr. J. Environ. Sci. Technol.    80.4 80.6 80.8 81 81.2Longitude ( in Degree)15.816.016.216.416.6Latitude (in Degree)1 234567891011121314151617181920212223242526272829 303132333435363738394041 424344451234 5678910111213141516171819202122 23 2425262728293031323334KoduruPateriMachlipatnamKosuruNidumoluVuyyuruGudiwadaRamapuramTenaliGunturMutturuBapatlaMantripalemBhattiproluGannavaramVijayawadaLegend:RiverTownWater samles North Krishna deltaSouth Krishna deltaKrishna River0km 11km 22km  Figure 1. Location of groundwater samples, Krishna delta, India.    MATERIALS AND METHODS  About the area  Krishna Delta (Longitude: 80024' - 81013'E, Latitude: 15042' - 16035'N) is formed by the holy river Krishna, close to the Bay of Bengal in the east coast of India. The river Krishna originates from the Western Ghats near Mahabaleswar, Maharashtra. After covering a distance of 480 km in Maharashtra, 291 km in Karnataka and 510 km in Andhra Pradesh (a total distance of 1281 km) it emerges into the Bay of Bengal and forms a delta (Figure 1). A large number of townships such as Tenali, Vijayawada, Guntur, Machlipatnam, Nizampatnam and Repalle are located in the delta region. The right side of the Krishna river is known as North Krishna Delta and the left side is known as South Krishna Delta. Most of the soil of this delta region is alluvium (Saxena et al., 2004). The flood basin on the right bank of the Krishna river is covered with black clay and grey clay underlain by brown silty clays and fine sands. The sand plain aquifers are the main source of water for agriculture and domestic purposes. The deltaic aquifers are recharged by direct infiltration of precipitation. The dug wells, bore wells and hand pumps are the major drinking water source in the Krishna delta (Saxena et al., 2003; Mondal et al., 2008). Average annual rainfall is 1050 mm and temperature is 28oC.   Groundwater sampling  The regions for the study of nitrate in groundwater cover both the urban and rural areas of Krishna delta (Figure 1). In total 79 groundwater samples, 37 were collected from dug wells, 39 from hand pumps, 2 from bore wells and 1 from the river Krishna. The depths of the water in dug wells are in between 1.7 to 20 m, whereas 8 to 35 m in hand pumps. The water samples were collected in double stopper 100 ml polythene bottles. The precise locations   of  the  sampling  points  were  determined  in  the  field Mondal et al.        267    Table 1. Place of sample collection, source, depth, Nitrate and pH, North Krishna Delta, India.   Sample No. Locality Type of well Depth of well (m) Nitrate (mg/L) pH 1 Vizayawada-I H.P. 13.0 10 7.7 2 Ramavarepalle H.P. 10.0 60 7.8 3 Vizayawada-II H.P. 35.0 42 7.5 4 Vizayawada-III D.W. 4.0 10 7.6 5 Chdavaram B.W. 53.0 10 7.5 6 Krishna river River water --- 10 7.2 7 Royyuru H.P. 15.0 40 7.6 8 Kantipadu D.W. 8.0 40 7.5 9 Uppuluru H.P. 16.0 54 7.7 10 Kesoropalle D.W. 3.6 104 7.8 11 Bapeshwaram B.W. 60.0 116 7.7 12 Tarogupalle H.P. 16.0 116 7.9 13 Indupalle D.W. 4.9 88 7.7 14 Venkatpragudu H.P. 16.0 56 7.5 15 Bollapadu H.P. 25.0 88 7.6 16 Koturu D.W. 2.9 46 7.5 17 Nappalle H.P. 20.0 10 7.6 18 Vuyyuru H.P. 15.0 10 7.6 19 Vallurupalem H.P. 20.0 10 7.6 20 Vallurupalem H.P. 10.0 56 7.7 21 Meduru H.P. 8.0 24 7.5 22 Krishapuram D.W. 2.1 20 7.8 23 Movva H.P. 28.0 10 7.6 24 Kudali H.P. 25.0 51 7.8 25 Paddapudi H.P. 10.0 10 7.6 26 Kapileshwaram H.P. 12.0 72 7.8 27 Modumuru H.P. 17.0 56 7.7 28 Elamoru D.W. 4.0 52 7.7 29 Pammaru H.P. 25.0 10 7.7 30 Gollavaluru H.P. 10.0 20 7.9 31 Angaluru H.P. 13.0 25 8.0 32 Kavataram D.W. 1.7 18 7.9 33 Vallamunudu D.W. 1.8 108 8.0 34 Pedana D.W. 1.9 125 8.3 35 Manganpudi D.W. 3.6 86 7.6 36 Chilkapudi D.W. 2.5 122 7.9 37 Sultanpur D.W. 2.1 56 8.2 38 Gudore D.W. 2.3 120 7.8 39 Nidumolu D.W. 2.5 44 7.9 40 Juthovaram H.P. 25.0 40 7.8 41 Chellapalle D.W. 2.1 62 7.8 42 Gollapalem D.W. 2.2 63 8.4 43 Kalkenpeta D.W. 3.4 130 7.8 44 Avanigadda H.P. 8.0 10 7.6 45 Nayalanka H.P. 26.0 10 7.6  (D.W: Dug well; B.W: Bore well, H.P: Hand pump and pH: -log10H+)   through the development of GARMIN-12 Channel Instrument, based on the principles of Global Positioning System (GPS), and the exact longitude and latitude of the sampling. The location of the sampling points is shown in Figure 1. Methodology  Measurement of pH was done by the portable pH-meter. Nitrate analyzer were used to measure the nitrate concentration in mg/L of 268      Afr. J. Environ. Sci. Technol.    Table 2. Place of sample collection, source, depth, Nitrate and pH, South Krishna Delta, India  Sample No. Locality Type of well Depth of well (m) Nitrate (mg/L) pH 1 Vallbhapuram H.P. 23.0 30 7.8 2 Imani H.P. 27.0 48 7.4 3 Attola H.P. 13.0 52 7.8 4 Kolakaluru D.W. 3.0 38 7.6 5 Chivaluru H.P. 10.0 30 7.8 6 Thuruluru H.P. 8.0 10 7.5 7 Anathavaram H.P. 24.0 10 7.4 8 Kolluru H.P. 17.0 10 7.6 9 Denapudi H.P. 33.0 24 8.2 10 Karumuru D.W. 3.0 40 7.5 11 Petaru D.W. 3.0 18 8.0 12 Repallur H.P. 15.0 10 8.0 13 Rajavolu D.W. 3.8 32 8.0 14 Gollapallu-I D.W. 3.8 68 7.8 15 Gollapallu-II D.W. 3.0 75 8.2 16 Inturu D.W. 2.0 40 7.8 17 Nanadivelugu D.W. 4.0 10 7.8 18 Munnupalle H.P. 8.0 62 7.5 19 Sunduru H.P. 16.0 10 8.0 20 Marlaluru D.W. 3.7 40 8.1 21 Panchalva D.W. 3.5 110 8.3 22 Peravil D.W. 4.5 20 7.6 23 Chevali D.W. 4.6 28 7.8 24 Kodimaru D.W. 3.3 24 8.2 25 Jampani H.P. 10.0 42 7.8 26 Mulpur D.W. 4.4 10 7.6 27 Kuchipidi D.W. 4.4 50 7.5 28 Tenali D.W. 20.0 105 7.8 29 Channavaranur D.W. 15.0 135 7.5 30 Eolapalli H.P. 8.0 20 7.6 31 Chebrolu D.W. 4.4 105 7.8 32 Narakoduru D.W. 9.5 33 7.8 33 Jagarlamudi H.P. 12.0 62 7.9 34 Molluluru H.P. 25.0 35 7.6  (D.W: Dug well; B.W: Bore well, H.P: Hand pump and pH: -log10H+)    groundwater (Saxena, 1991). The results of nitrate concentrations are shown in Tables 1 and 2.   RESULTS AND DISCUSSION  The studies carried out on the nitrate contents have shown that concentration varies from 10 - 135 mg/l. The nitrate concentration in different ranges, classified these water samples into six categories and shown in Figure 2. This figure shows, 27% samples of north Krishna delta and 21% of south Krishna delta have low nitrate (10 mg/l); 22% samples of north and 47% of south in between 11 to 45 mg/l; 27% samples of north and 21% of south are in between 46 to 75 mg/l; 7% samples in north, but there is no sample in south which have nitrate of 76 to 100 mg/l. It seems to be at a high pollution level and the water can be used other than drinking purposes. 16% in north and 9% in south of water samples have a high value of nitrate (101-125 mg/l) and extremely high nitrate content (>126 mg/l) is reported in 2% of groundwater samples in both the regions. The isolevels of nitrate concentration have been drawn and shown in Figure 3. This figure indicates that the behavior of nitrate enrichment is high in Gudiwada, Gannavaram, Kosuru, Nidumolu and Muchlipatnam areas of north Krishna delta. The south Krishna delta, which is near to sea coast, is free from ni-           Mondal et al.        269    010203040500-10 11-45 46-75 76-100 101-125 126-135Nitrate (in mg/l)(%) of Groundwater SamplesNorth Krishna deltaSouth Krishna delta  Figure 2. Sample percentage based on different ranges of nitrate concentration.    Table 3. Range of Nitrate concentrations and their mean values in groundwater samples of Krishna delta.  Sl. No. Locality/type of wells Number of samples Range of nitrate conc. (mg/L) Mean Conc. of nitrate (mg/L) North Krishna delta (a) Dug well 18 10-130 72 (b) Bore well 2 10-116 63 (c) Hand pump 24 10-116 37 South Krishna delta (a) Dug well 19 10-135 52 (b) Bore well Nil Nil Nil (c)  Hand pump 15 10-62 30    nitrate pollution except in and around Tenali town, Mutturu and west of Bhattiprolu. In general the possible sources of nitrate that lead to nitrite in groundwater are nitrogen rich sediments, interaction of groundwater with nitrogen rich industrial waste, inputs of organic nitrogen into soil, biological denitrogen fixation by micro organisms,inputs of human and animal waste, water in unused dug wells, stagnate water and nitrogenous inorganic fertilizers etc (Hammer, 1986; Dudley, 1990; Barnes and Smith, 1992). pH varies from 7.2 to 8.4. It indicates that groundwater is mildly alkaline. During the field investigation, no such industries were found which could transport the nitrate rich industrial waste in the studied area. Krishna delta is known for its fertile soil, which is very much favorable for the cultivation of mainly paddy and sugarcane. The inorganic nitrogen-nous fertilizers are used to increase the growth rate of this agricultural production (Singh et al., 2004). The com-mon inorganic nitrogen fertilizers, which are widely used in the region, are urea, calcium ammonium nitrates, ammonium chloride and calcium phosphates etc. The nitrogen content in these fertilizers is high and varies from 20 to 50%. Mostly these fertilizers are soluble in water and easily release nitrogenous mass (Burt et al., 1993). In chemical process, fertilizer reacts with water/moisture and decomposes into amino acid. These amino acids are degraded to ammonium sulphates and ammonium amines, which in tern oxidize to nitrites. In atmospheric condition nitrites are very unstable and soon converted into nitrates. In view of the nitrates solubility in water, they rapidly increase the nitrate pollution level in the groundwater. The range of nitrate in different water sources and their mean value are shown in Table 3. On the basis of Figure 2 and Table 3, it is  observed  that  the  270      Afr. J. Environ. Sci. Technol.    80.4 80.6 80.8 81 81.2Longitude ( in Degree)15.816.016.216.416.6Latitude (in Degree)KoduruPateriMachlipatnamKosuruNidumoluVuyyuruGudiwadaRamapuramTenaliGunturMutturuBapatlaMantripalemBhattiproluGannavaramVijayawadaLegend:RiverTownKrishna River0km 11km60 mg/LNitrate counturs  Figure 3. Isolevels of nitrate concentration in Krishna delta.    groundwater of north Krishna delta is more polluted than south. Field study and personal communication with con-cern people indicate that high quantity of inorganic nitrogen fertilizers was used in this region. The nitrate data also indicate pollution level is more in dug wells compared to hand pumps/bore wells (Table 3). It is mainly because of poor dug wells structure. In practice nitrogen fertilizers are supplied in the agriculture field at a period before the crop grows but some time the crop yields  may  not  be  as  high  as  anticipated  because  of unrealistic yield or adverse weather condition and this can result in runoff and leaching of residual nitrate in the soil and in turn pollute the groundwater.   Conclusions  Groundwater of north Krishna delta is more polluted than  south Krishna delta in term of nitrate. Its level in this region 49% dug wells and 31% hand pumps have exceeded the desirable limits, which indicate that dug wells are more nitrate contents compared to hand pumps/bore wells. The high nitrate level in groundwater is due to excessive utilization of nitrogenous fertilizers, insecticides and pesticides for agricultural purposes. To reduce the nitrate level immediately the following steps can be adopted: High nitrate content of poor dug wells can be reduced by the maintenance of it’s structure, Leaching of nitrate from the inorganic fertilizers can be minimized by control use of nitrogenous fertilizers and de-nitrification technique is useful to reduce the nitrate content of groundwater.   ACKNOWLEDGEMENTS  Authors are grateful to Dr. V.P. Dimri, Director, National Geophysical Research Institute, Hyderabad, for his kind permission to publish this paper and the anonymous reviewer for providing his the valuable suggestions to improve the manuscript.      REFERENCES  Barnes CJ, Smith GD (1992). The origin of high nitrate groundwater in the Australian arid zones. Jr. of Hydrol. 137:181-197.  Burt TP, Heathwaite AL, Trudgill ST (1993). Nitrate process patterns and Management. John Willey, New York, p.444. Canter LW (1997) Nitrate in groundwater. Lewish Publishers, p.263. Chettri M, Smith GD (1995). Nitrate pollution in groundwater in selected District of Nepal. Hydrogeol. J. 3:71-76. Dudley CJ (1990). Nitrates the threat to food and water. Green Print, London, pp.71-76. Hammer MJ (1986). Water and waste water Technology. John Willey, New York, p. 550. Lindsay W L (1979). Chemical equilibrium in soils. Jhon Willey, New York, p.149. Mondal NC, Singh VS, Saxena VK, Prasad RK (2008). Improvement of groundwater quality due to fresh water ingress in Potharlanka Island, Krishna delta, India. Environ. Geol. 55(3): 595-603. Perlistein NA, Attala R (1976). Neurologic sequel of plubism in children. Clinical Pediatics, 5:292-298. Piskin R (1973). Evaluation of nitrate content of groundwater Hall Couty Nebraska. Groundwater 11(6): 4-13. Reddy KSN (1981). The essentials of forensic medicine and toxicology.  5th Edn. Sugune, Hyderabad, p.81.                               Mondal et al.        271    Saxena VK (1991). Study of the groundwater resources of the west and east Godavari District, A.P, India. Water Ecology, Pollution and Management, Editors, S. Pitchaiah and S. S. Rao, Chug publication, Allahabad, India, pp. 125-147. Saxena VK, Mondal NC, Singh VS (2004). Identification of seawater ingress using Strontium and Boron in Krishna delta, India. Curr. Sci. 86(4): 586-590. Saxena VK, Singh VS, Mondal NC, Jain SC (2003). Use of hydrochemical parameters for the identification of fresh groundwater resources, Potharlanka Island, India. Environ. Geol. 44(5):516-521.  Singh VS, Saxena VK, Prakash BA, Mondal NC, Jain SC (2004). Augmentation of groundwater resources in saline ingress coastal deltaic area. Tech. Rept. No. NGRI-2004-GW-422, p.61. Thind GS (1982). Role of toxic element in human on experiment condition. J. Air and water pollution control,  22:267-270. WHO (1993). Guide lines for drinking water quality. 2nd edition. World Health Organization, p.267.                               

Occurrence of elevated nitrate in groundwaters of Krishna delta, India

https://www.ajol.info/index.php/ajest/article/download/135614/125120

Occurrence of elevated nitrate in groundwaters of Krishna delta, India

Abstract

Similar works

Full text

Available Versions

AJOL - African Journals Online