IMPACT OF MINING ON SURFACE WATER QUALITY IN THE WESTERN PART OF SANDUR SCHIST BELT, KARNATAKA, INDIA – A PRELIMINARY INVESTIGATION

G.V. Gaonkar 1* , J.T. Gudagur 1 and T.K. Lakkundi 2 . 1. Department of Geology, Karnatak Science College, Dharwad. 2. Department of Geology, Arba Minch University, Ethiopia. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


ISSN: 2320-5407
Int. J. Adv. Res. 4 (10), 1475-1482 1476 leafless during the dry months. The flowering and fruiting are generally far advanced before the first flush of new leaves appears with the showers in April -May.
Study area comprises of hills and plane lands. Eastern segment of the study area has hilly terrain represented by the Sandur Schist Belt having several mining leases for Iron and Manganese Ores (Fig. 2) and western segment is a plateau with granitic terrain. The lithological units include granitic gneiss, younger granite, quartzite, migmatites and metavolcanics.
Most part of the study area is accessible through a network of all-weather roads, both metalled-and unmetalledroads. However, entry to mining areas is either restricted or denied especially since this study involves impact of mining on the water resources.
The area experiences a semi-arid type climate with dry and hot summer. The maximum temperature is experienced during May and the minimum during December month in general. Temperature varies between 22°C and 43°C and the relative humidity of the region varies from 38% to 95%. The climate is influenced by South-West and North-East monsoons. The average annual rainfall in the area is 870.7mm. It receives about 60.22% of the annual rainfall during South-West monsoon (June-September), 22.21% during North-East monsoon (October-November) and balance 17.57% of rainfall occurs as sporadic in other months of the year (Indian Council of Forestry Research and Education, 2012).

Materials and Methods:-
Since the study is concerned about the impact of iron-and manganese-ore mining on surface water resources, part of the Sandur Schist Belt within the study area having several mining leases and part of the area west of the schist belt (i.e. eastern half of the study area) is given preference while collecting the water samples.
Representative surface water samples from 18 locations (Fig. 2) were collected at the end of the monsoon season in 2014 from those parts of the study area where the chances of effect of ores and gangue on surface water resources are predominantly higher. These areas include hill slopes and foothills of Sandur schist belt and, the relatively flat terrain west of the schist belt (i.e. eastern half of the study area) into which the surface runoff will be flowing carrying along with it the products of mining.
Samples were collected in one liter polythene cans after thoroughly washing them with the water to be collected. Before collecting, samples were filtered so as to remove the suspended matter. Sample locations were recorded using a GPS-receiver.

Results and Discussions:-
Results of the partial physico-chemical analysis of 18 representative water samples from the study area are presented in Table 1.      Chloride concentration in water samples ranges between 4 and 150 mg/L with an average of 38.81 mg/L. Acceptable limit of chloride in drinking water as per IS standard is 250mg/L and all the samples are within this limit.
Fluoride concentration varies from BDL to 1.55 mg/L with an average of 0.38 mg/L. The safe limit is 1.5 mg/L and only one sample exceeds this limit which is collected from Garag Tank.
Permissible limit for Iron is 0.1 mg/L as per WHO (2004) standards whereas all the samples show Fe concentration above this limit of WHO standard. But as per the IS and CPCB standards, the permissible limit is 1.0 mg/L. According to these standards only 3 samples exceed the Iron concentration limit. One sample collected from a check dam, another from a natural tank and the third one from the T.B.Dam where the wash-off from the hill slope joins the dam water. All these three samples are from the hill bottom. Concentration of Mn varies from BDL to 0.21 mg/L.
Iron is an essential element in human nutrition and requirement of iron depends on age, sex, physiographical status etc. The largest fraction in humans is present as haemoglobin, myoglobin and haem containing enzymes. Increased iron absorption results in genetic disorder, haemochromatosis-disease that can damage the body's organs, lead to heart disease, liver problem and diabetes. Low iron can lead to anaemia, fatigue, concentration disorder and affects mental development (Verma et. al., 2012;Das, 2014;Yadav and Jamal, 2015).

Conclusions:-
The surface water samples analyzed were compared with different sets of standards. It is alarming to note that the Fe-content of all samples exceeds the maximum permissible limit given by the World Health Organization (2004). The haphazard dumping of iron ore and waste as well as poor stabilization methods have resulted in the erosion/wash-off during rainy season thereby increasing the Fe-content of surface water bodies.

Recommendations:-
Considering the presence of excess iron in all the samples when compared to the WHO (2004) standards, the following recommendations are made; a) Strict compliance of approvals/conditions imposed by the statutory/regulatory authorities. b) Systematic stock of ore and dumping of waste should be at proper locations and practiced strictly. c) Effective plans have to be drawn to restore the land affected due to mining by green belt development which would help in many ways to minimize the negative impact on environment. d) Use of waste for backfilling and brick manufacturing has to be planned and implemented.