INTRODUCTION:

The surface water in rivers, lakes and ponds are easily accessible for human consumption and other commercial activities as settled one-third of the fresh water requirement in the world by these natural precision (Jalal and Sanakumar, 2013). The water quality of surface water is governed by the natural and anthropogenic processes, including rainfall, erosion, hydrologic features, industrial and agricultural activities (Sarthi and Singh, 2013). The widespread change in water quality of inland aquatic systems has been reported due to the rapid development of industries, agriculture and human settlement (Bhat and Pandit, 2014). There is a growing freshwater crisis throughout the world, as the freshwater resources are getting depleted and polluted in equal measures.

The evaluation and maintenance of good water quality are very crucial to protect the integrity of different surface water resources (Singh and Jaya Kumar, 2015). During the last few years, numerous attempts were made to evaluate the spatiotemporal water quality of different aquatic systems in India (Bhat and Pandit, 2014; Govindasamy and Viji, 2012; Chandra et al, 2012; Laishram and Dey, 2014). Water quality monitoring is one of the key tools, to identify and keep a check on the pollution status, and ensure about the efficiency of management plans.

The Akilpur lake is one of the largest natural oxbow lakes of fresh water in Chapra district and located in the flood plain of the Ganga-river. There is no study has been conducted to monitor the status of water quality of this lake. Thus, this study is carried out to understand the water quality in this lake from January 2021 to December 2021. Data generated during this study can be used as a baseline data for future research on this lake.

METHODS AND MATERIALS:

The Akilpur lake was formed by the meandering of the Ganga-river and during monsoon it get connected to nearby water resources. The lake was divided into three major blocks (Inlet, mid-lake and outlet) based on the previous report published by Ramakrishna et al (2002).

The water samples were collected from 14 sites as three for each inlet and outlet block and eight sampling locations were identified for mid-lake monthly from January 2021 to December 2021 in polyethylene bottles in triplicate and mixed to get a composite sample for each sampling location. The collected samples were marked carefully, stored in the icebox and immediately carried to the laboratory for analysis. The analysis of physicochemical parameters was carried out by using standard methods of American Public Health Association (2005).

RESULTS AND OBSERVATIONS:

The monthly variations of different physicochemical parameters of water in the inlet, mid-lake and outlet part of the lake are shown in figure 1 to figure 9.

pH: Water pH is one of the important parameters which plays a crucial role in different life-sustaining chemical reactions. Generally, confined inland waters in India are alkaline in nature [17-18]. In this study, pH of surface water varied from 7.20 to 8.93. It was minimum with water of the inlet channel during the month of February, while maximum value was observed in outlet water during the same month (Figure 1).

Figure 1: Monthly pH variation in Akilpur lake

Electrical conductivity (EC):

The electrical conductivity of water is a measure to confirm the presence of different ions in it and also about its purity. It depends on the concentration of different ions, nutrients, and dissolved solutes. The EC recorded for water samples in this study was ranged between 49μS/cm to 472μS/cm. The minimum value of EC was observed in mid-lake during September while the maximum was in inlet water during March (Figure 2).

Figure 2: Monthly EC variation in Akilpur lake

Dissolved oxygen (DO):

It is important to the metabolic activities of aquatic organisms. Low DO value indicates about the organic pollution; while relatively high DO confirm the good health of an aquatic ecosystem. The variation of DO in this study was observed in a range of 2.0 mg/l to 9.8 mg/l. It was observed minimum and maximum in inlet water during the month of January and July respectively (Figure 3).

Figure 3: Monthly DO variation in Akilpur lake

Alkalinity:

The total alkalinity of water varied from 140 mg/l to 600 mg/l. The minimum and maximum value of total alkalinity was observed in inlet water during the months of January and February (Figure 4).

Figure 4: Monthly DO variation in Akilpur lake

Phosphate (PO43-):

The concentration of phosphate in water samples was found in a range of 0 mg/l to 0.2 mg/l. It was found minimum in mid-lake water during the month of June and maximum in outlet water during September (Figure 5).

Figure 5: Monthly DO variation in Akilpur lake

Nitrate (NO3-):

The concentration of Nitrate in water samples was found in a range of 0.46 mg/l to 5.2 mg/l. It was found minimum in mid-lake water during the month of January, and maximum in outlet water during June (Figure 6).

Figure 6: Monthly Nitrate variation in Akilpur lake

Potassium (K):

Potassium is an important dietary material for all organisms for maintaining their body metabolism rate. The concentration of Potassium in water samples was found in a range of 1.0 mg/l to 6.2 mg/l. Its minimum concentration was observed in outlet water during the month of October and was the maximum in mid-lake water during July (Figure 11).

Figure 7: Monthly Potassium variation in Akilpur lake

Calcium (Ca):

The concentration of Calcium in water samples was found in a range of 0 mg/l to 78.0 mg/l. Its minimum concentration was observed in outlet water during the month of May while it was the maximum in mid-lake water during November (Figure 12).

Figure 8: Monthly Potassium variation in Akilpur lake

Usually, calcium is found in all natural waters, but the discharge of different sewage and waste waters enhances its concentration.

Magnesium (Mg):

The concentration of Magnesium in water samples was found in a range of 0 mg/l to 32.8 mg/l. Its minimum concentration was observed in mid-lake water during the month of May while it was the maximum in inlet water during October (Figure 13).

Figure 9: Monthly Potassium variation in Akilpur lake

Discussions:

The annual average of water parameters was compared with the annual average value published by Ramakrishna et al (2002). The results are summarized on the seasonal basis and compared with the surface water quality standard (Table 1). Three seasons were considered, including post-monsoon (November to February), pre-monsoon (March to June) and Monsoon (July to October).

Table 1: Seasonal variation of Water parameters in Akilpur lake during study period

Parameters	Winter (Nov-Feb)		Summer (Mar-Jun)		Monsoon (Jul-Oct)		Water Standards
Parameters	Range	Mean±SD	Range	Mean±SD	Range	Mean±SD	Water Standards
pH	7.1-8.7	8.11±0.31	7.20-8.91	8.15±0.30	7.32-8.70	8.09±0.28	6.5-9
EC(µs/cm)	210-470	330±51	208-472	286±61	79-314	211±11	1000-2250
DO (mg/l)	2.9-8	5.19±1.93	4.4-8.6	7.12±0.90	5.8-9.3	8.08±0.78	4-6
Alkalinity (mg/l)	140-600	255±91	160-320	249±32	161-351	250±48	-
Phosphate (mg/l)	.002-.188	.058±.050	0-0.13	.019±.005	.003-0.2	.032±.005	-
Nitrate (mg/l))	0.47-4.84	2.43±1.09	1.04-5.3	2.53±1.03	1.92-4.0	2.352±0.62	20-50
Potassium (mg/l)	1-6.2	3.45±1.08	3-5.2	4.16±0.58	1.5-5.4	3.02±1.92	-
Calcium (mg/l)	10-78	38±16	0-40	13±11	26-78	36±10.50	-
Magnesium (mg/l)	1.2-15	5.72±3.6	0-33	4.80±5.60	3-22	8.32±4.02	24-28

The pH of this lake water was reported in the same range in the previous studies also (Singh and Roy, 1990; Ramakrishna et al, 2002). The relatively low value of pH in monsoon season could be due to a sudden increase in the concentration of organic matters through run-off from agriculture land, which led to an increased CO₂ concentration and ultimately reduce the pH (Verma et al, 2011). All the samples were observed under the range of safe limit (6.5 - 9.0), suggested by BIS for surface water quality (BIS, 1991). The water was neutral to alkaline in nature throughout the year. Seasonally, the average pH of the lake water was observed in a sequence of Monsoon < Post-monsoon ≅ Pre-monsoon (Table 1).

The high value of EC is an indication of pollution and eutrophic status of an aquatic ecosystem. Relatively low EC during monsoon season might be because of rainwater, which dilutes the ion concentration. EC of all samples was observed under the prescribed limit (< 2250 μS/cm) by BIS (1991). The conductivity of the lake water was also found in the same range as reported by Singh and Roy (1990); and Ramakrishna et al (2002). The average conductivity of the lake water was observed in a sequence of Monsoon < Pre-monsoon < Post-monsoon (Table 1).

It is reported in different studies that the DO is high during active photosynthesis, while it used to reduce when water temperature, organic load and microbial activity increase in the aquatic system (Kumar, 1996). In this study, very less DO was recorded during the post-monsoon season, which might happen because of insufficient solar radiation in the months of December and January. Fourteen samples (8.33% of total) during December and January months were having DO less than 4.0 mg/l (Figure 4), which is the minimum prescribed value for surface water quality (BIS, 1991) in comparisons of previously reported DO for this lake (Singh and Roy, 1990; Ramakrishna et al, 2002), it was found relatively lesser in this study during the post-monsoon season. Seasonally, the average DO of the lake water was observed in a sequence of Post-monsoon < Pre-monsoon < Monsoon (Table 1).

The alkalinity of water gives an idea about the presence of natural salts. The salts of weak acids and bicarbonate ions are the key reasons for alkalinity in water, which used to accumulate more because of depressed photosynthesis over respiration during post-monsoon season. The total alkalinity of the lake in this study was observed higher than previously reported by Singh and Roy (1990) and Ramakrishna et al (2002). The seasonal variation of alkalinity during the study was observed in a sequence of Pre-monsoon ≤ Monsoon < Post-monsoon (Table 1).

Phosphorous is one of the most important micronutrients in deciding the productivity of an aquatic system. It occurs in different forms, including particulate phosphorous, active phosphate, orthophosphate etc. (Pradhan, 2014). The high concentration of phosphate during the post-monsoon season could be because of extensive cloth washing by laundry persons and continuous discharge of sewage water. Whereas in monsoon season, its concentration was relatively low. It might be due to the quick growth of phytoplankton, which feeds on phosphates. Its concentration was observed very high in the water as compared to a previous report (Singh and Roy, 1990; Ramakrishna et al, 2002). The seasonal variation of phosphate concentration was observed in a sequence of Pre-monsoon < Monsoon < Post-monsoon (Table 1).

Nitrate is another important nutrient, which plays a key role in deciding the productivity of an aquatic system. The high concentration of nitrate usually causes algal blooms in lakes (Verma et al, 2011). Nitrate concentrations in all water samples were always found below the given standard limit (20-50 mg/l) for surface waters (BIS, 1991). Its concentration was observed very high in the water as compared to a previous report (Singh and Roy, 1990; Ramakrishna et al, 2002). The main sources of nitrate to this lake were direct sewage discharge and agricultural run-off. The seasonal variation of nitrate concentration was observed in a sequence of Monsoon < Post-monsoon < Pre-monsoon (Table 1).

The seasonal variation of Potassium concentration was observed in a sequence of Monsoon < Post-monsoon < Pre-monsoon (Table 1).

Calcium is one of the elements which exist in divalent form Ca⁺² ion in water. It is the main component of different aquatic shells and bones of vertebrates (Jhingaran, 1975). The seasonal variation of Calcium concentration was observed in a sequence of Pre-monsoon < Monsoon < Post-monsoon (Table 1). Its concentration was observed very high in the water as compared to a previous report (Ramakrishna et al, 2002).

As like calcium, magnesium also exists in divalent form Mg⁺² ion in water. Usually, Magnesium is always found with calcium in the waters but in very low concentration. It is the main component of chlorophyll, which is important for photosynthesis Dayashankar and Saksena, 1992). The seasonal variation of Magnesium concentration was observed in a sequence of Pre-monsoon < Post-monsoon < Monsoon (Table 1). Its concentration in all water samples (except one sample of outlet water in the month of June) was always found below the given standard limit (24.28 mg/l) for surface waters (BIS, 1991). Its concentration was observed very high in the water as compared to a previous report (Ramakrishna et al, 2002).

CONCLUSION:

The results obtained during this study were compared with the standard limits given by Bureau of Indian Standards for surface water quality and previously published results of the same lake. The values of all parameters were found in the range of prescribed limits, except DO during the month of December and January. All the parameters exceeded the previously published values, which clearly indicated about enhanced level of pollution. pH, nitrate, and potassium showed a similar pattern of seasonal variation. Likewise, EC and chloride; DO, hardness, and sulfate; alkalinity, phosphate, and calcium were also followed the same pattern in seasonal variability. It is also concluded from this study that mid-lake waters were not too much affected by different pollution sources, in comparisons of the inlet and outlet waters. A large annual increase in the concentration of phosphate and nitrate has clearly indicated about its eutrophication. So it can be recommended for this study to keep a check on the direct discharge of different pollutants.

REFERENCES:

1. Jalal FN and Sanalkumar MG (2013): Water quality assessment of Pampa River in relation to Pilgrimage season, Int J Res Chem Env, 3(1): 341-347.

2. Bhat SA and Pandit AK (2014): Surface Water Quality Assessment of Wular Lake: A Ramsar Site in Kashmir Himalaya, using discriminate analysis and WQ, J Ecosystem.

3. Sarthi PP and Singh AK (2013): A Simple approach about the Characteristics of Available Surface Water in the Bihar State of India, Geosciences, 3(2): 68-76.

4. Govindasamy C and Viji J (2012): Present Status of Maniyampattu and Puliyanthangal Lakes Ranipettai, Tamilnadu, India, World Appl Sci Journal, 16(10): 1409-1415.

5. Singh AK and Jayakumar S (2015): A review on methods to estimate CH4 and N2O flux in terrestrial ecosystem, Clim Ch Env Sus, 3(2):104-113.

6. Chandra S, Singh A and Tomar PK (2012): Assessment of Water Quality Values in Porur Lake Chennai, Hussain Sagar Hyderabad, and Vihar Lake Mumbai, India, Chem Sci Trans, 1(3): 508-515.

7. Laishram J and Dey M (2014): Water quality status of Loktak Lake, Manipur, Northeast India and Need for Conservation Measures: A study of Five Selected Villages, Int J Sci and Res Pub 4.

8. Singh JP and Roy SP (1990): Investigations on the limnology of the Kawar Lake (In: Recent trends in Limnology Editor: VP Agrawal and P Das), Society of Biosciences, Muzaffarnagar (UP), pp 557-467.

9. Ramakrishna Muley, Siddiqui SZ and Pandey AK (2002): Limnology: Wetland Ecosystem Series 4, Fauna of Kabar Lake: 2001. Zool. Surv. India, 2002, pp. 15-21.

10. APHA (2005): Standard methods for the examination of water and wastewater (21st ed.), Washington, D.C: American Public Health Association.

11. Verma P, Chandawat D, Gupta U and Solanki H (2011): Water Quality Analysis of an Organically Polluted Lake by Investigating Different Physical and Chemical Parameters, Int J Res Chem Environ, 2(1):105-111.

12. BIS (1991): Indian standards for surface water, Bureau of Indian Standards, New Delhi.

13. Kumar, A (1996): Comparative study on diel variation of anabiotic factor in lentic and lotic freshwater ecosystems of Santhal Paragana (Bihar), J Environ Pollution, 3: 83-89.

14. Pradhan VP (2014): Estimation of nutrient load in a fresh water lake, Int J of Life Sciences, 2 (1): 84-89.

15. Jhingran VG (1975): Fish and Fisheries of India. Hindustan Publ Corp, India, pp 954.

16. Dagaonkar and Saksena DN (1992): Physicochemical and biological characterization of a temple tank, Kaila Sagar, Gwalior, Madhya Pradesh. J Hydrobiol, 8 (1): 11-19.

Received on 17.02.2022 Modified on 24.02.2022

Research J. Science and Tech. 2022; 14(1):47-52.

DOI: 10.52711/2349-2988.2022.00007