Current World Environment

Introduction

Water is addressed as a necessary resource and life preservative. It is required for most human activities like – drinking, cooking bathing, washing, agriculture, industry, recreation, navigation and fisheries etc. About 75% of the world’s surface area is covered with water. Out of which 97% of the earth’s water is in the ocean, not fit for human use due to its high salt content. Remaining 2% is locked in polar ice caps and only 1% is available as fresh water in rivers, lakes, streams reservoirs and ground water, suitable for human consumption. Now-a-day, water quality issues have become a significant concern due to the growth of population, urban expansion and technological development. Water can be easily contaminated in different ways through unregulated or regulated but not well designed and monitored disposal practices. In India’s case, the future is a bit more-worse, since we have only 2.45% of the word’s landmass supporting 16% of the world’s population and our freshwater resource does not exceeding 4% of the global water resources (Kumar 2005). Apart from availability, continuous water pollution due to disposal of sewage, industrial and mining wastes also threatens to reduce the available quantity of usable water and more and more of our ground and surface water resources including lakes, ponds and rivers are being categorized as polluted (Subramanian et al. 2000; Mohan et al 2000; Kumaresan et al. 2006; Singh et al. 2007; Singh et al. 2013). Access to safe drinking water remains an urgent necessity, as 30 % of urban and 90 % of the rural Indian population still depends completely on untreated surface or groundwater resources (Kumar et al. 2005).Access to drinking water in India has increased over the past few decades with the tremendous adverse impact of unsafe water for health (Singh et al. 2013).Scarcity of clean and potable drinking water has emerged in recent years as one of the most serious developmental issues in many parts of West Bengal, Jharkhand, Orissa, Western Uttar Pradesh, Andhra Pradesh, Rajasthan and Punjab (Tiwari and Singh 2014).

Water quality index (WQI) is defined as a technique of rating that provides the composite influence of individual water quality parameter on the overall quality of water (Singh et al. 2013). Water Quality Index, a technique of rating water quality, is an effective tool to assess quality and ensure sustainable safe use of water for drinking (Tiwari et al. 2014). Water quality index is one of the most effective tools to communicate information on the quality of any water body (Rizwan and Gurdeep 2010).WQI is an a superior way to the understanding of water quality issues by integrating complex data and generating a score, which ultimately describes the water quality status (Tiwari et al. 1985; Singh, D. F. 1992; Rao, S.N; 1997; Mishra et al. 2001). One of the major advantages of WQI is that, it incorporates data from multiple water quality parameters into a mathematical equation that rates the health of water quality with number (Yogedra and Puttaiah 2008).

Mining is one of the major activities causing water pollution and threatens the quality surface water. Water pollution in mining areas is mainly due to overburden (OB) dumps, surface impoundments, mine water, industrial effluents, acid mine drainage, tailing ponds etc. (Singh et al. 2013). River and other streams are not far from the mining industries and it contaminate continuously from point as well as non-point source. Waste generation due to the operation and expansion of mining and industrial activity in Goa is going to be a serious negative impact on the water resource in near future. The problems of water quality degradation and its adverse impacts on availability of potable and irrigation water, soil quality and agricultural productivity, and biodiversity in the area have been attracting increasing attention of people. The aim of this study is to assess the quality of surface water for the suitability of drinking and domestic purpose in Goa mining region. Study Area Goa is the 25^th State of India, attaining statehood in May 1987.It lies between the latitudes 14°53'54" N & 15°40'00" N and longitudes 73°40'33" E & 74°20'13" E with geographical area of 3,702 km² and coastline of 105 km. The study area comprises of 5 mining Talukas namely Bicholim, Sattari, Dharbandora, Quepem and Sanguem encompassing an area of 1513 km². Study area entails all the areas wherein mining activities of Goa are encompassed along with a belt of five km from the lease boundary (Fig 1).

Figure 1: Sampling location map of the Goa Mining.  Click here to View figure

Materials and Methods

The water samples were collected from thirty six (36) different locations in all two seasons, Pre-monsoon post-monsoon season. Sampling locations were selected on the basis of different land use pattern (agricultural, mining, residential and barren etc.). Care was taken to collect subsequent samples from same location in all season. The Samples were taken from 10 to 15cm below the water surface using acid washed plastic container to avoid unpredictable changes in characteristic as per standard procedures (APHA, 2005). Details of sampling locations along with their latitude and longitude are illustrated in (table 4).

Water Quality Index

WQI’s aim at giving a single value to the Water quality of a source reducing great amount of parameters into a simpler expression and enabling easy interpretation of monitoring data (Singh et al. 2013).Water Quality Index (WQI) is a technique of rating that provides the composite influence of individual parameter on the overall quality of water. WQI a well known method as well as one of the most effective tools to express water quality that offers a simple, stable, reproducible unit of measure and communicate information about water quality to the policy makers and concerned citizens (Singh et al. 2013).  The  weights  for  various  water  quality  parameters  are  assumed  to  be  inversely  proportional  to  the recommended standards for the corresponding parameters. One of the major advantages of WQI is that, it incorporates data from multiple water quality parameters into a mathematical equation that rates the health of water quality with number (Brown et al. 1970). In this study for the calculation of water quality index, twelve important parameters were chosen. The WQI has been calculated by using the standards of drinking water quality recommended by the World Health Organization (WHO), Bureau of Indian Standards (BIS), and Indian Council for Medical Research (ICMR).The weighted Arithmetic index method has been used for the calculation of WQI of the water body. Further quality rating or sub index was calculated using the following expression.

q_n = 100 (V_n - V_io)/ (S_n - V_io)       (1)

(Let there be n water parameter and quality rating or sub index (q_n) corresponding to n^th parameter is a number reflecting the relative value of this parameter in the polluted water with respect to its standard permissible value)
q_{n =} Quality rating for the n^th water quality parameter
V_n = Estimated value of the n^th parameter at a given sampling station
S_n = Standard permissible value of the n^th parameter
V_n = Ideal value of n^th parameter in pure water. (i.e., 0 for all other parameter except the parameter pH and Dissolved oxygen (7.0 and 14.6 mg/l respectively)

Unit weight was calculated by a value inversely proportional to the recommended standard value S_nof the corresponding parameter.

W_n = K/S_n    (ii)

where W_n= Unit weight for the n^th parameters,
S_n= Standard value for n^th parameters,
K = Constant for proportionality.

The overall water quality index was calculated by aggregating the quality rating with the unit weight linearly:

WQI = Σ_qn W_n/ ΣW_n     (iii)

Different levels of water quality index and their respective water quality status were given in Table-1. Various parameters and their unit weight were calculated and summarized in Table -2 with their standards and recommended agencies.

Table 1 : Descriptive category of WQI values   Click here to View table

Results and Discussion

The World Health Organization (WHO), Bureau of Indian Standards (BIS), and Indian Council for Medical Research (ICMR) for the drinking water together with its corresponding status categories of WQI are given in Tables 1, Table 2, Table 3 and Table 4, respectively. The WQI of water samples were found in the range of 34 to 83 in post monsoon, 28 to 81 in winter, 34 to 86 in summer and 23 to 107 in monsoon season. The WQI for all samples were found in the range of 34 to 107. Almost 94% of the total water samples were found in range of good and medium except SW2 and SW35 which were found to be in poor categories. Out of 36 water samples only two (6%) were found within poor category, it is due to transportation of iron ore and mining activities.  Huge overburden dumps are piled in and around mining areas were suffered during monsoon seasons due to leaching. Among all the of the water samples, the percentage (%) of WQI categories Good (47.22%), Moderate (47.22) and Poor (5.56%) were observed in all four the seasons (Fig. 2).

Figure 2: WQI Categories of Samples (%) in all the seasons  Click here to View figure

 

Table 2: Drinking water standards recommending agencies and unit weights (All values are in mg/L, except pH and Electrical conductivity).  Click here to View table

 

Table 3: Season wise statistical variation in WQI values.  Click here to View table

 
Table 4: Details of sampling locations and status of surface water quality.

S.NO	Sample Code	Location	Type of water	Latitude(N)	Longitude(E)	Status
1	SW 1	Assonora River in Bardez Taluka	River	73°54’19.2”	15°37’11.9”	Good
2	SW 2	Tributary of Moide River in Shrigao, of Bicholim Taluka	River	73°53’43.3”	15°36’23.4”	Poor
3	SW3	Valvanti River in Pariye of Sattari Taluka	River	74°03’01”	15°35’17.8’’	Good
4	SW4	Mandovi River near Amona Jetty in Bicholim Taluka	Nallah	73°58’2.9”	15°31’49.1”	Moderate
5	SW5	Tributary of mandovi, Surla nallah in Bicholoim Taluka	River	74°03’15”	15°29’41.8”	Good
6	SW6	Mandovi River in Khnodguinum Bicholim Taluka	River	74°02’20.8”	15°30’42”	Good
7	SW7	Kudnem River Shonshi nallah Sattari Taluka	River	74°02’23.7”	15°32’37”	Good
8	SW8	Advai nallah in Sattari Taluka	Nallah	74.5°05’20”	15°30’40.4”	Moderate
9	SW9	Cudnem river in arvalem Bicholim Taluka	River	74°01’36.5”	15°33’2.1”	Good
10	SW10	Cudnem river of cudnem in bicholim Taluka	River	74°00’50.8”	15°32’45.3”	Good
11	SW11	Cudnem river in gauthan of Bicholim Taluka	River	74°00’17.7”	15°33’8.2”	Moderate
12	SW 12	Ragda river in guleli of Sattari Taluka	River	74°06’25.2”	15°28’22.6”	Moderate
13	SW 13	Mandovi river in Usgao of Dharbandora Taluka	River	74°06’8.4”	15°26’38.1”	Good
14	SW14	Khandepar river in codli village of Dharbandora Taluka	River	74°07’37”	15°21’29.8”	Moderate
15	SW15	Sigao in Khandepar of Dharbandora Taluka	River	74°00’45.2”	15°29’57.1”	Moderate
16	SW16	Khandepar river in collem village of Dharbandora Taluka	River	74°14’9.7”	15°20’43.8”	Good
17	SW17	Sanvordem nallah in Sanguem Taluka	Nallah	74°07’37”	15°16’37.9”	Good
18	SW18	Selalulim Dam in Sanguem Taluka	Reservoir	74°10’39.2”	15°12’50.4”	Good
19	SW19	Sanguem river in Sanguem Taluka	River	74°08’58.7”	15°13’57.2”	Good
20	SW20	Kushavati river in kevona village of Quepem Taluka	River	74°07’55.0”	15°08’10.7”	Good
21	SW21	Kushavati river in Sulcorna village of Quepem Taluka	River	74°07’38.6”	15°30’8.0”	Good
22	SW21	Sal river in Betul village of Quepem Taluka	River	73°57'12.1"	15°8'17.44"N	Moderate
23	SW23	Zuari river in Sanvordem of Quepem Taluka	River	74°6'43.9”	15°15'57.6”	Moderate
24	SW24	Mayem lake in Bicholim taluka	Lake	73°56'21.7"	15°34'31.71”	Good
25	SW25	Mandovi near cottombi jetty Bicholim Taluka	Jetty	74°01'32.9"	15°28'52.4"	Good
26	SW26	Mandovi river sarmanas jetty in Bicholim taluka	Jetty	73°57'34.39"	15°32'41.20"	Moderate
27	SW27	Moide river in sirsaim jetty in Bardez Taluka	Jetty	73°52'53.65"	15°36'53.161"	Moderate
28	SW28	Mandovi river in Naveli jetty in Bicholim Taluka	Jetty	74°0'42.68"	15°29'58.884"	Moderate
29	SW29	Mandovi river nera Rumda jetty in Bicholim Taluka	Jetty	74°02'40"	15°26'.56"	Moderate
30	SW30	Mandovi river in mayni jetty in bicholim Taluka	Jetty	73°59'58.96"	15°30'34.671"	Good
31	SW31	Zuari river Capxem jetties in Quepem Taluka	Jetty	74°5'47.583"	15°16'8.688"	Moderate
32	SW32	Zuari river nera shelvaaana jetty in quepem Taluka	Jetty	74°5'22.277"	15°16'12.97"	Moderate
33	SW33	Khandepar river in Opa village of Ponda Taluka	Jetty	74°5'47.583"	15°16'8.688"	Moderate
34	SW34	Mandovi river near cumbharjua canal in Ponda Taluka	pond	73°57'30.36"	15°32'1.632"	Moderate
35	SW35	Zuari river near Marmugao port in Marmugao Taluka	Harbour	73°47'27.2"	15°24'48.4"	Poor
36	SW36	Mandovi river nera Surla jetty in Bicholim Taluka	Jetty	74°01'44.0"	15°28'.51.4"	Moderate

Conclusion

On the basis of the above discussions, it may be concluded that the WQI for all samples were found in the range of 34 to 107 in the four seasons. The highest value of WQI was observed during the monsoon season while the lowest value was during the post monsoon season. The water quality analysis shows that the 47.22 % surface water samples were found as Good category and 47.22 % moderate category can be use for direct consumption while 5.56 % belongs to poor category shows that the water is not suitable for direct consumption in Goa mining region. After treatment of that water samples can be used for drinking purposes in the study area.

Acknowledgement

The authors are thankful to Ministry of Environment and Forest (MoEF) for financial support. Authors are also grateful to Prof. D.C. Panigrahi, Director, Indian School Mines, Dhanbad for his valuable support during the study. One of the authors is grateful to Indian School of Mines/MHRD/Govt. of India, for granting a great support.

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