Physico-chemical assessment of ground water qualities of some areas of Imphal East district of Manipur during post-monsoon – 4^th phase

Nandababu Singh Laishram

Department of Chemistry, D.M. College of Science, Imphal – 795001 Manipur, India

*Corresponding Author E-mail: l.nandababu@yahoo.com

ABSTRACT:

Fifteen ground water samples (represented by S-1 to S-15) were collected from different locations of Imphal East district of Manipur during post-monsoon of 2014. They were analyzed for physico-chemical parameters like temperature, pH, TDS (total dissolved solids), electrical conductivity (EC), total alkalinity (TA) (and hence CO₃^2- and HCO₃^-), total hardness (TH), Ca²⁺, Mg²⁺, Na⁺, K⁺ and Cl^-. Only ground waters represented by S-14 (of Achanbigei Makha Leikai) and S-15 (of Achanbigei Mayai Leikai) are found to be fit for drinking purpose from physico-chemical analysis point of view. However, ground waters represented by S-1 to S-13 may also be used for drinking purpose in absence of alternate sources and further it is necessary to treat them so as to keep high values of total alkalinity (for S-1 to S-13) and total hardness value for S-3 within acceptable limit (200 mg/L) of BIS standard for drinking water. All the fifteen ground waters are fit for other domestic purposes also. Besides these, all the fifteen ground waters (S-1 to S-15) are fit for irrigation purpose also.

Further, strong positive correlations exist between TDS and each of electrical conductivity and total alkalinity for the ground waters (S-1 to S-15). Again correlation co-efficient data reveals that presence of NaHCO₃ and KHCO₃ in such ground waters, attribute to high values of both TDS (and hence EC) and total alkalinity (TA). Further, strong correlations of Ca²⁺ and Mg²⁺ with TH (total hardness), indicate the direct proportionality of total hardness values to concentrations of Ca²⁺ and Mg²⁺ ions for the different ground waters (S-1 to S-15).

KEYWORDS: Physico-chemical parameters, drinking, irrigation, , post-monsoon, BIS and correlation co-efficient.

INTRODUCTION:

Of the total global water resources, ground water is about 0.6% and out of this, only 0.3% is extractable economically¹. There is increasing demand for ground water all over the world day by day to meet the requirements for human consumption for drinking and other domestic purposes, and also for irrigation as well as industrial purposes. This increasing demand for ground water is because of the fact that with increasing population growth all over the world, rate of urbanization increases and consequently many places of surface water bodies in cities, towns and even in villages are converted into sites for construction of houses, buildings, offices, institutions, commercial areas, industrial sites etc. which leads to decrease in surface water bodies to a large extent. And consequently, it leads to more demand for ground water all over the world. But ground water is not always safe for drinking, other domestic, irrigation and industrial purposes. It is, therefore, necessary to monitor qualities of such ground water from time to time. With a view to this objective, many researchers of different countries had already started extensive investigations on qualities of ground water in order to examine whether such ground waters are fit for drinking, other domestic, irrigation and industrial purposes.^2-7. In India also many researchers of different states, studied on ground water qualities for drinking, other domestic and irrigation purposes mainly.^8-14

This research work aims at carrying out physico-chemical assessment of ground water qualities of some areas of Imphal East district of Manipur during post-monsoon of 2014.

MATERIALS AND METHODS:

Chemicals used for this research work, were of AR grade and were used as received. Fifteen ground water samples were collected from hand pumps of fifteen different locations of Imphal East district of Manipur during post-monsoon of 2014. The geographical positions (longitudes and latitudes) for the different sampling sites, were measured with a GPS instrument and they are detailed in table –1 below:

Table-1: Locations of different sampling sites (with geographical positions)

Sample code no. (with source)	Sampling sites (locations)	Longitude	Latitude
S-1 (Hand pump)	Kairang Awang Leikai (1) (Near Primary School)	93^057^/15.48^//E	24^050^/45.27^//N
S-2 (Hand pump)	Kairang Awang Leikai (2)	93^057^/19.79^//E	24^050^/49.62^//N
S-3 (Hand pump)	Kairang Chingya (1) (Near foothill)	93^057^/43.66^//E	24^050^/59.45^//N
S-4 (Hand pump)	Kairang Chingya (2) (Near paddy field)	93^057^/45.99^//E	24^050^/58.26^//N
S-5 (Hand pump)	Heingang Mayai Leikai	93^056^/45.46^//E	24^051^/38.21^//N
S-6 (Hand pump)	Heingang Awang Leikai (Near foothill)	93^056^/25.19^//E	24^052^/19.78^//N
S-7 (Hand pump)	Khundrakpam Awang Leikai (near foot hill)	93^059^/24.54^//E	24^053^/34.09^//N
S-8 (Hand pump)	Tangkham Maning Leikai (Near big pond)	93^058^/30.19^//E	24^053^/59.52^//N
S-9 (Hand pump)	Chingkhu Awang Leikai (Near foothill)	93^059^/21.91^//E	24^054^/25.66^//N
S-10 (Hand pump)	Wangkhei Khunou (Near foothill)	93^059^/51.32^//E	24^055^/47.78^//N
S-11 (Hand pump)	Sinam kairangthel (Near foothill)	93^058^/59.35^//E	24^056^/50.62^//N
S-12 (Hand pump)	Yumnam Khunou Awang Leikai Sanjenbam (Near foothill)	94^000^/12.94^//E	24^056^/24.35^//N
S-13 (Hand pump)	Ishikha (Ichikha) Awang Leikai (Near foothill)	94^000^/31.34^//E	24^056^/19.05^//N
S-14 (Hand pump)	Achanbigei Makha Leikai	93^056^/05.39^//E	24^052^/06.80^//N
S-15 (Hand pump)	Achanbigei Mayai Leikai	93^056^/08.55^//E	24^052^/21.20^//N

All the ground water samples were collected in well sterilized polythene bottles of onr litre capacity each. For sampling and preservation, strict guidelines were followed¹⁵. The fifteen ground water samples were analyzed for physico-chemical parameters such as temperature, pH, TDS ( total dissolved solids) and electrical conductivity (EC), total alkalinity(TA), CO₃^2-, HCO₃^- total hardness (TH), Ca²⁺ , Mg²⁺, Na⁺, K⁺ and Cl^-_. Parameters such as temperature, pH, TDS and electrical conductivity were measured during sampling for each ground water sample while parameters such as total alkalinity, total harness, Ca²⁺ and Cl^- were determined in departmental research laboratory using standard methods¹⁵. Concentration values of parameters like CO₃^2-, and HCO₃^- were calculated from corresponding total alkalinity values while that of Mg²⁺, were calculated from the difference of total hardness and calcium hardness for each ground water sample. Furhter concentrations of Na⁺ and K⁺ for each ground water sample, were determined using a flame photometer instrument. Brief methods and instruments /equipments used for determinations and measurements of various physico-chemical paramenters are shown in table-2 given below:

Table-2 : Instruments and brief methods used for measurements and determinations of physico-chemical parameters of ground water samples
Physico-chemical parameters measured / determined	Instruments and brief methods used
Temperature	TDS Meter (TDS-3) (TDS/Temp.) (HIMEDIA, India)
pH	pHep® Pocket-sized pH Meter (HI98107) (HANNA Instruments, Romania)
TDS (Total dissolved solids)	TDS Meter (TDS-3) (TDS/Temp.) (HIMEDIA, India)
Electrical conductivity (EC)	Conductivity Tester (Dist 3: HI 98303) (HANNA Instruments, Romania)
Total alkalinity (TA)	Titrimetric method with standard HCI solution using phenolphthalein and methyl orange indicators
CO3^2- and HCO3^-	By calculation method from total alkalinity values
Total hardness (TH)	EDTA titrimetric method (using Eriochrome Black T Indicator)
Calcium (Ca^2+)	EDTA titrimetric method (using Murexide indicator)
Magnesium (Mg^2+)	By calculation method
Sodium (Na^+) and Potassium (K^+)	Flame Photometer 128 (Systronics, India)
Chloride (Cl^-)	Argentometric titrimetric method (Using K2CrO4 indicator solution)

The values of parameters such as RSC (residual sodium carbonate) and SAR (sodium adsorption ratio) which were used for assessing irrigation water quality for the different ground water samples, were calculated using the following relationships^16-17:

where ionic concentrations were expressed in

milli-equivalents / litre (meq/L).

RESULTS AND DISCUSSION:

All the fifteen ground water samples (S-1 to S-15) were found to be colourless and odourless. The values of different physico-chemical parameters for the different ground water samples, are detailed in table-3 given below:

Table-3: Values of physico-chemical parameters for ground water samples
Sample code no.	Temper-ature (^oC)	pH	TDS (mg/L)	Electrical Conducti-vity (EC) (µS/cm)	Total alkalinity (TA) (as CaCO3) (mg/L)	HCO3^- (mg/L)	Total hardness (TH) (as CaCO3) (mg/L)	Ca^2+ (mg/L)	Mg^2+ (mg/L)	Na^+ (mg/L)	K^+ (mg/L)	Cl^- (mg/L)
S-1	23.3	6.7	309	660	350	427	140	21.6	20.9	91.2	1.2	7.1
S-2	23	7	356	746	395	481.9	144	21.6	21.9	105.7	1.3	11.3
S-3	22.8	7.3	277	603	290	353.8	222	42.5	28.2	48.1	1	31.2
S-4	22.4	7.4	342	732	320	390.4	182	29.7	26.2	90.3	1.3	62.4
S-5	22.3	7	243	533	270	329.4	96	17.6	12.6	66.5	1.5	9.9
S-6	22.2	7.4	228	487	270	329.4	164	32.1	20.4	49.4	1.1	5.7
S-7	23.2	7.4	208	454	250	305	164	32.1	20.4	38.5	0.9	7.1
S-8	22.3	7.7	402	854	490	597.8	148	27.3	19.4	148.9	1.2	12.7
S-9	23.8	7.5	275	586	325	396.5	116	20.8	15.6	94.6	1.1	7.1
S-10	23.3	7.3	193	413	220	268.4	156	24	23.3	31.9	0.8	5.7
S-11	21.8	7.5	226	493	270	329.4	118	23.2	14.6	67.3	0.9	4.3
S-12	22.2	7.4	223	487	265	323.3	194	32.1	27.7	34	1	5.7
S-13	22.4	7.2	210	456	250	305	186	32.1	25.8	28.7	0.8	5.7
S-14	19.9	7	160	343	175	213.5	62	12.8	7.3	39.1	1	5.7
S-15	21.6	6.8	161	343	175	213.5	66	12.8	8.3	37.5	1	5.7

On the basis of values of different physico-chemical parameters for different ground water samples (S-1 to S-15), the following discussion has been made:

Temperature:

Temperatures for fifteen ground waters (S-1 to S-15) are in the range 19.9-23.8⁰C (table-3).S-14 has the lowest temperature (19.9⁰C) while that of S-9 is the highest (23.8⁰C).

pH Values:

The pH values for the fifteen ground water samples (S-1 to S-15) range from 6.7 to 7.7 (table-3). All these values are within the acceptable limit(6.5 - 8.5) of BIS standard for drinking water as well as that of WHO¹⁸_.^-19 S-1 has lowest value of pH(6.7) while S-8 has highest value of it (7.7).

TDS (Total dissolved solids):

The TDS values for the fifteen ground water samples (S-1 to S-15) are in the range 160-402 mg/L (table-3). All these TDS values are below the acceptable limit (500 mg/L) of BIS standard for drinking water¹⁸. S-14 has lowest value of TDS (160 mg/L) while that of S-8 is highest (402 mg/L). As the TDS values for the fifteen ground water samples are less than 1000 mg/L, all of them may also be used for other domestic purposes not only for drinking purpose²⁰.

Electrical conductivity (EC):

The electrical conductivity values for the fifteen ground water samples (S-1 to S-15) range from 343µS/cm to 854 µS/cm (table-3). Each of S-14 and S-15 has the least value (343µS/cm) while that of S-8 is highest one (854 µS/cm).

Total alkalinity (TA):

The values of total alkalinity for the fifteen ground water samples (S-1 to S-15) are in the range 175 – 490 mg/L (table-3). Each of S-14 and S-15 has least value of total alkalinity (175 mg/L) while that of S-8 is highest (490 mg/L). Only S-14 and S-15 have total alkalinity values below the acceptable limit (200 mg/L) of BIS standard for drinking water while those of remaining ground water samples (S-1 to S-13) have their values above the acceptable limit but below the permissible limit (600 mg/L)¹⁸.

CO₃^2- and HCO^-₃:

The concentrations of CO₃^2- for all the ground water samples (S-1 to S-15) are almost found to be zero as the phenolphthalein alkalinity (P-alkalinity) for each of them is zero. However, the concentrations of HCO₃^- for the ground water samples range from 213.5 mg/L to 597.8 mg/L (table-3). Each of S-14 and S-15 has least concentration of HCO₃^- (213.5 mg/L) while that of S-8 is highest (597.8 mg/L).

Total hardness (TH):

The total hardness values for the fifteen ground water samples (S-1 to S-15) are in the range 62-222mg/L (table -3). S-3 has highest value of total hardness (222 mg/L) while S-14 has lowest value of it (62 mg/L). S-1 to S-2 and S-4 to S-15 have their total hardness values below the acceptable limit (200 mg/L) while that of S-3 is above the acceptable limit but below the permissible limit (600 mg/L) of BIS standard for drinking water.¹⁸

Further, S-14 and S-15 belong to soft water category (0-75 mg/L); S-1, S-2, S-5, S-8, S-9 and S-11 belong to moderately hard water category (75-150 mg/L) while S-3, S-4, S-6, S-7, S-10, S-12 and S-13 belong to hard water category (150-300 mg/L).²⁰

Calcium (Ca²⁺):

The concentrations of Ca²⁺ for the fifteen ground water samples (S-1 to S-15) range from 12.8 mg/L -42.5 mg/L (table-3). All the concentration values of Ca²⁺ for different ground water samples, are below the acceptable limit (75 mg/L) of BIS standard for drinking water.¹⁸ Both S-14 and S-15 have the lowest concentration of Ca²⁺ (12.8 mg/L) while that of S-3 is highest (42.5 mg/L).

Magnesium (Mg²⁺):

The concentrations of Mg²⁺ for the fifteen ground water samples (S-1 to S-15) are in the range
7.3 – 28.2 mg/L (table-3). S-14 has lowest concentration of Mg²⁺ (7.3mg/L) while that of S-3 is highest (28.2 mg/L). However, all the concentration values of Mg²⁺ for the fifteen ground waters (S-1 to S-15), are below the acceptable limit (30 mg/L) of BIS standard for drinking water.¹⁸

Sodium (Na⁺):

About sodium contents for the fifteen ground water samples (S-1 to S-15), the concentrations of sodium for different ground waters are in the range 31.9–148.9 mg/L (table-3). S-13 has lowest concentration of sodium (28.7 mg/L) while that of S-8 is highest (148.9 mg/L). However, all the concentration values for the fifteen ground waters, are below the threshold limit (200 mg/L ) of WHO.¹⁹

Potassium (K⁺):

All the fifteen ground water samples (S-1 to S-15) have low concentrations of K⁺ ranging from 0.8 mg/L to 1.5 mg/L (table-3). Each of S-10 and S-13 has the lowest concentration of K⁺ (0.8 mg/L) while that of S-5 is highest (1.5 mg/L).

Chloride (Cl^-):

The concentrations of chloride for the fifteen ground water samples (S-1 to S-15), are in the range4.3-62.4mg/L (table-3). S-11 has lowest concentration of Cl^- (4.3 mg/L) while that of S-4 is highest (62.4mg/L). However, all these concentration values of Cl^- for the fifteen ground waters(S-1 to S-15),are below the acceptable limit (250 mg/L) of BIS standard for drinking water¹⁸.

Ground water quality for irrigation:

The values of RSC (residual sodium carbonate) and SAR (sodium adsorption ratio) for the fifteen ground water samples (S-1 to S-15), are shown below in table-4:

Table-4: Values of RSC and SAR for different ground water samples
Sample code no.	S-1	S-2	S-3	S-4	S-5	S-6	S-7	S-8	S-9	S-10	S-11	S-12	S-13	S-14	S-15
RSC values (meq/L)	4.20	5.02	1.36	2.76	3.48	2.12	1.72	6.84	4.18	1.29	3.04	1.42	1.28	2.26	2.18
SAR values	3.4	3.8	1.4	2.9	3.0	1.7	1.3	5.3	3.8	1.1	2.7	1.1	0.9	2.2	2.0

From the above table-4, it is clearly seen that the values of RSC for different ground water samples (S-1 to S-15),are in the range 1.28-6.84 meq/L. S-13 has lowest value of RSC (1.28meq/L) while that of S-8 is the highest (6.84meq/L). The values of RSC for S-3,S-6,S-7,S-10 and S-12 to S-15, are within the category of good quality of water for irrigation(1.25-2.50 meq/L).^1,16

From table-3, it is seen that electrical conductivity values for S-1 to S-7 and S-9 to S-15 are within the category of good quality for irrigation (250-750 µS/cm).¹⁷

Above all, the SAR values for S-1 to S-15, range from 0.9 to 5.3 and all these values are below the excellent category of water for irrigation (SAR value upto 10) ^1,17. So, all the ground waters (S-1 to S-15) are fit for irrigation purpose.

Statistical analysis based on correlation co-efficient (r) values:

The calculated values of correlation co-efficient (r) of different variable pairs of physico-chemical parameters for the fifteen ground water samples (S-1 to S-15), are detailed in table-5 given below:

Table-5: Correlation Co-efficient( r) values between variable pairs of various physico-chemical parameters for different ground water samples

	Temp.	pH	TDS	EC	TA	HCO3^-	TH	Ca^2+	Mg^2+	Na^+	K^+	Cl^-
Temp.	1
pH	0.177	1
TDS	0.410	0.267	1
EC	0.413	0.279	0.999	1
TA	0.429	0.341	0.959	0.958	1
HCO3^-	0.429	0.341	0.959	0.958	1	1
TH	0.374	0.440	0.339	0.357	0.299	0.299	1
Ca^2+	0.537	0.531	0.240	0.263	0.224	0.224	0.951	1
Mg^2+	0.261	0.345	0.390	0.404	0.335	0.335	0.973	0.854	1
Na^+	0.061	0.231	0.905	0.898	0.917	0.917	-0.051	-0.111	-0.003	1
K^+	0.067	-0.209	0.603	0.604	0.507	0.507	-0.185	-0.245	-0.130	0.627	1
Cl^-	0.071	0.181	0.469	0.479	0.226	0.226	0.408	0.361	0.416	0.253	0.357	1

From the above table-5, it is clearly seen that TDS shows very strong positive correlations with both EC and TA (r=0.999 and 0.959 respectively) showing that both EC and TA are directly proportional to TDS for different ground water samples. Na⁺ shows very strong positive correlations with TDS, EC and having r values equal to 0.905, 0.898 and 0.917 respectively. Similarly, K⁺ also shows moderately strong positive correlations with TDS, EC and (r = 0.603, 0.604 and 0.507 respectively). The above correlations of both Na⁺ and K⁺ with TDS, EC and show that both Na⁺ and K⁺ are mostly present in the forms of soluble NaHCO₃ and KHCO₃ respectively in the different ground waters (S-1 to S-15) and both the salts attribute to high values TDS (and hence EC) and TA for different water samples. Further, high values of TH is due to high concentrations Ca²⁺ and Mg²⁺ ions (as salts) (r = 0.951 and 0.973 respectively).

CONCLUSIONS:

From the above discussion based on various experimental results for fifteen different ground water samples (S-1 to S-15), the following conclusions are drawn:

(i) Only ground waters represented by S-14 and S-15, are fit for drinking purpose as their corresponding values of physico-chemical parameters, are below/ within the acceptable limits of BIS standard for drinking water as well as that of WHO, as is evident from physico-chemical analyses point of view.

(ii) In case of remaining ground waters (S-1 to S-13), they are fit for drinking purpose in absence of alternate sources as their TA (total alkalinity) values and total hardness value for S-3 are above the acceptable limit but below the permissible limit of BIS standard for drinking water. So, suitable treatment is necessary so as to keep the values of total alkalinity for them within the acceptable limit of BIS standard for drinking water.

(iii) All the ground waters are suitable for other domestic purposes.

(iv) All the ground waters (S-1 to S-15) are fit for irrigation purpose.

(v) Strong positive correlations are shown between TDS and each of electrical conductivity (EC) and total alkalinity (TA). From correlation co-efficient values point of view, high values of both TDS (total dissolved solids) and total alkalinity (TA) are due to presence of NaHCO₃ and KHCO₃ mainly in different ground waters (S-1 to S-15). Further, strong positive correlations of Ca²⁺ and Mg²⁺ with total hardness (TH) reveals the dependence of high values of total hardness on high concentrations of both Ca²⁺ and Mg²⁺ ions.

ACKNOWLEDGEMENTS:

The author is mainly thankful to those local people of different sampling sites for their cooperation extended to the author.

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Received on 10.12.2015 Modified on 24.12.2015

Accepted on 29.12.2015 © AJRC All right reserved

Asian J. Research Chem. 8(12): December 2015; Page 751-756

DOI: 10.5958/0974-4150.2015.00121.2