Climate and Rainfall
MATERIAL AND METHODS
RESULTS AND DISCUSSION
Groundwater manganese concentration from the Chandrapur district of Central India was assessed during winter 2012. Groundwater sampling was carried out by grab sampling method in 36 sampling locations comprised of 34 hand pumps and two dug wells. Groundwater samples for manganese were preserved by adding conc. HNO3 (1 mL for 100 mL of water sample). Groundwater manganese concentrations were estimated by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES, Dv 7000, Germany). Groundwater iron concentration from the study area during winter 2012 was in the range of 0.0015-1.85 mg/L (SD±0.36). Groundwater manganese concentration in seven water samples were above the permissible desirable limit of Indian Standards for drinking water (IS 10500:2012, desirable limit for Mn, 0.3 mg/L max.). This elevated concentration of manganese in groundwater from the study area can be attributed to weathering of mineral bearing rocks, mining activities and also to some extent to anthropogenic activities. Spatial distribution of manganese was observed in the study area. Further, shallow, deep and very deep well water had variable manganese concentration. Upper earth surface had lower manganese concentration, however present, can be attributed to anthropogenic activities whereas deeper earth surface had higher manganese concentration that can be assigned to geogenic origin.
Keywords: Central India, Chandrapur, Groundwater quality, Heavy metal, Manganese
Manganese is one of the most abundant metals in soils, where it occurs as oxides and hydroxides, and it cycles through its various oxidation states. Manganese occurs principally as pyrolusite (MnO2), and to a lesser extent as rhodochrosite (MnCO3). More than 25 million tonnes of manganese are mined every year, representing 5 million tons of the metal, and reserves are estimated to exceed 3 billion tonnes of the metal. The main mining areas for manganese ores are South Africa, Russia, Ukraine, Georgia, Gabon and Australia. Manganese is widely distributed in soils, sediments, rocks, water, ambient air and biological materials. Within 16 km Earth’s crust, manganese occurs at a concentration of ~950 mg/kg. Thus, manganese is the second most abundant heavy metal, and in the frequency list of elements it occupies 12th place. The Earth core contains about 1.5% manganese (Falbe and Regitz, 1999), and the manganese content of rocks ranges from 350 to 2000 mg/kg, with highest concentration in mafic rocks. Manganese is an essential element for all species. Some organisms, such as diatoms, mollusks and sponges, accumulate manganese. Fish can have up to 5 ppm and mammals up to 3 ppm in their tissue, although normally they have around 1 ppm.
Various studies pertaining to groundwater manganese concentration in different parts of the world are carried out. According to Jang (2012) to locate clean and safe groundwater in the Choushui river alluvial fan of Taiwan based on drinking water quality standards revealed that groundwater in study area was not appropriate for drinking use without any treatments because of high ammonimum-N, iron, manganese, and/or arsenic concentrations. Natural background levels for iron, manganese and some ions in groundwater of the Campania region of southern Italy showed a value of about 1400 µg/L for manganese and 600 µg/L for iron. The widespread high content of iron and manganese was due to reducing conditions related to extensive marshlands present in past and to presence of thick peat levels, especially in the vadose zone (Ducci and Sellerino, 2012). Khan et al., (2013) reported that manganese concentration was within desirable limit except for one sample which was within permissible limits of WHO. It has been reported that up to 42% of the analyzed groundwater samples Fe2+ content was beyond the Nigerian Industrial Standard whereas up to 25% for manganese in the vicinity of Okpara coal and Obwetti fireclay mines, near Enugu town, Nigeria (Utom et al., 2013). Purushotham et al., (2013) reported manganese concentration from 2.3 to 4340 µg/L with an average of 2171 µg/L in Ranga Reddy district of Andhra Pradesh. Except for two locations concentration for manganese was within desirable limit. The use of manganese in some fertilizers contributed to water and air pollution. Source identification study of heavy metal concentration in industrial hub of Unno, India revealed that the maximum concentration was found in samples for various heavy metals analyzed was above the maximum permissible value as set by USEPA 2009. The results of multivariate analysis showed that cadmium, copper, manganese, nickel, lead and zinc were correlated with anthropogenic sources, while iron and chromium were associated with lithogenic sources (Dwivedi and Vankar, 2014). According to Alam and Umar (2013) for trace elements in groundwater of Hindon-Yamuna interfluve region showed relatively high concentration for Pb, Se, Fe and Mn in few samples. In a study for heavy metal pollution in groundwater from Amik plain, southern Turkey found that highest manganese concentration was 1026.10 µg/L and 26 samples exceeded the permissible limit of 100 µg/L set by TWPCR (2008) (Agca et al., 2014). Spatial and temporal variation of manganese in drinking water for eight communities in south-east Quebec, Canada showed highly variable concentrations depending on location (<1-2, 700 µg/L ), daily, or seasonal variation were minimal. Flushing tap for 5 minutes did not significantly reduced total manganese concentration for 4 out of 5 sampling locations. The efficiency of reverse osmosis and ion exchange for total manganese removal was consistently high while activated carbon provided variable results. Manganese concentration in distribution system was equal or lower than at inlet, indicating that sampling at inlet of distribution system was conservative. The decline in total manganese concentration was linked to higher water residence time in distribution system (Barbeau, 2011). Hafeman et al., (2007) reported that infants exposed to water manganese greater than or equal to 0.4 mg/L (WHO standard, 2003) had an elevated mortality risk during the first year of life compared with unexposed infants in Bangladesh. Correlation analysis of groundwater colouration from mountainous area of Ghana reported weak negative correlations were found between temperature and iron and manganese. Iron and manganese showed strong positive correlation (Amfo-Out et al., 2014). In a study carried out for heavy metals in groundwater of Yenagoa, Bayelsa state, Nigeria it was reported that iron concentration ranges from 0.06 mg/L to 53.10 mg/L while manganese between 0.12 to 2.34 mg/L. The primary source of the iron in water was geogenic and could be derived from minerals like goethite, haematite, and limnonite in the Benin formation or from plant debris in the alluvial soils (Nwankwoala et al., 2011). Dhar et al., (2008) reported that iron concentration spanned nearly three orders of magnitude from 2.4 ± 2 µmole/L to 1694 ± 704 µmole/L and manganese concentration were not quiet variable and ranged from 2.6 ± 1 µmole/L to 96 ± 6 µmole/L. There was no consistent relationship between depth profiles of iron and manganese at each site. Concentration of iron and manganese rose during dry season and dropped during wet season. Khan et al., (2012) reported that manganese exposure from drinking water and children’s academic achievement was correlated. Water manganese above WHO standard of 400 µg/L was associated with 6.4 percentage score loss (95%, CI=0.5, 12.3) in mathematics achievement test scores, adjusted for water arsenic and other socio demographic variables. No significant association between water manganese and academic achievement in Bangla and English language were found. Manganese concentration in groundwater of industrial area of Ghaziabad varied from 0.0 to 350 mg/L with a mean of 0.040 mg/L. Out of total sample analyzed (n=60), 11.66% had higher manganese concentration than prescribed limit of WHO (0.1 mg/L) (Savita Kumari et al., 2014). Geochemical mobilization of iron and manganese in Sohag governorate, Egypt was found that about 60% of groundwater and all surface water samples had Mn concentration within the safe limits of 400 µg/L. The distribution of groundwater manganese was highly dispersed. The variation of iron and manganese levels in groundwater may be attributed to chemical weathering of rock minerals (Langmuir, 1997), redox reactions, biodegradation and soil leaching (Hesterberg, 1998; Melegy et al., 2014). Trace elements from groundwater of Brisinghpur area of Satna district of Madhya Pradesh reported that manganese concentration was in the range of 0.020 to 0.282 mg/L. About 30% of sample exceeded the desirable limit (0.1 mg/L), however they do not exceeded the permissible limit (0.3 mg/L). Higher concentration was related to geology of the area. It was also reported that elevated manganese concentrations were also associated with iron ores as well as lateritic mining (Tiwari et al., 2013). According to Oyem et al., (2015) for regional composition of groundwater of Agbor and Owa communities of Nigeria showed higher iron (27%) content in Boji-Boji Agbor area and manganese was highest (31%) in Boji-Boji Owa.
It has been reported in local newspapers and through discussion with local inhabitants that red coloured water was coming out from hand pumps and turning utensils into red in colour. The purpose of this study is to develop an understanding of regional groundwater quality in the Chandrapur district in Central India where coal mining is an important industry. The study strives to acquire knowledge of the quality of groundwater with respect to its metal content especially manganese. This study specifically aims at predicting spatial distribution of manganese concentration in the region.
Chandrapur district is located in the eastern edge of Maharashtra in ‘Vidarbha’ region lying between 19’250 N to 20’450 N and 78’500 E to 80’100 E and covers an area of 11,364 km2 of central India (Figure 1). This district is considered to be one of the most important mining deposits of Maharashtra, India. Intense mining activities along with natural processes like rock alteration attributes to high major and trace metal concentration in the groundwater and stream water.
Chandrapur district is well known for its sprawling coal mines, thermal power plant, pulp and paper industry, cement plants, etc. There are several mines in the Chandrapur district viz. coal, limestone, fluorite, chromium, fireclay, iron, copper, etc. The mineral based industrial development and rapid urbanization has resulted in environmental contamination and degradation and its effects are now being felt. The mining activities disturb the groundwater balance. It is also the fact that it increases groundwater contamination as mine water has lower pH values in the ranges of 2-4, which dissolves metals from the surrounding geological formations. Wastewater released from mine pit contains suspended solids, low pH, sulphates, major and trace metals, etc. Minerals present in Chandrapur district are presented in Figure 5.
Climate and Rainfall
The Climate of the district is characterised by a hot summer and general dryness throughout the year except during south-west monsoon season, i.e., June to September. The temperature rises rapidly after February till May, which is the hottest month of the year. The mean daily maximum temperature during May is 42.8 °C and the mean daily minimum temperature during December is 12.2 °C. The normal annual rainfall varies from about 1200 to 1450 mm. It is minimum in the western part around Warora and gradually increases towards east and reaches maximum around Brahmapuri (CGWB, 2009). Rainfall pattern in Chandrapur district is depicted in Figure 2.
Chandrapur district can be divided into two physiographic regions i.e., plane region in valleys of Wardha, Penganga and Wainganga Rivers and Upland Hilly Region. The plane region is made up of widely spread and flat terrain occurring mostly along Wardha River. In Wainganga valley flat terrain exhibits rolling topography with residual hills in the southern part, while in the northern part (Brahmapuri taluka) wide alluvial flood plains are observed. In Penganga valley, flat terrain covers very little area in south western part of the district. The upland hilly region lies between Wardha and Wainganga rivers comprising parts of Warora, Chandrapur, Mul and Brahmapuri talukas. The south western part of the district in Penganga basin and covering parts of Rajura and Gadchandur talukas exhibit hilly topography (Figure 3). The entire area of the district falls in Godavari basin. Wardha, Wainganga and Penganga are the main rivers flowing through the district. These three rivers along with their tributaries rise in the upland within the district and drain the entire district (CGWB, 2009).
The major water bearing formations in the district are Alluvium, Lower Gondwana Sandstones, Deccan Trap Basalt, Vindhyan Limestone and Archean metamorphics. Amongst these, the lower Gondwana Sandstones, particularly Kamthi Sandstone forms the most potential aquifer. A map depicting the hydrogeological features is shown in Figure 7 (CGWB, 2009).
Geologically, Chandrapur district forms a part of Gondwana sedimentary basin. The Gondwana sedimentation took place in Wardha valley where Gondwana sediments have overlay the Archean rocks. Lithologically Chandrapur district presents a variety of statigraphic units right from Archean to recent alluvium and laterites. The Archaean rocks comprise gneisses, quartzites, banded haematite quartzites (BHQ), schists with basic intrusives like pyroxinites, amphibolites, etc. The rocks are intruded by several dykes, trending NE–SW, are exposed in the eastern part of Chandrapur district. Iron ore series and Sakoli series are equivalent in age. Iron ore series constitutes the important iron deposits of Chandrapur district. The rocks are quartzite, BHQ, quartzite schist, phyllites, etc. The Dharwars have been intruded on a very large scale and comprise of granites, granitoids and gneisses. The Vindhyans are represented mainly by flaggy and massive limestones, shale’s and sandstones. The lenticular patches of breccia with angular fragments cemented by calcareous matrix are found at several places in limestones. The limestones are dolomitic at places. Sandstones and quartzities are hard copact and forms ridges. Lower Gondwana includes hard quartzite, sandstones, grits, and conglomerates. The sandstones are fine grained whitish colored and calcareous in nature. The shales are of red colour and are found in small patches in the south-eastern part of Chandrapur district. The Deccan trap lava formation covers small part of the district. The amygdaloidal softer variant varieties usually show calcite filling. In the district, Alluvium is mostly of fluviatile origin and comprises sand, silt and clays. It is generally found along the banks of nallas and rivers. Its thickness varies from 8 to 35 m as observed along the Wardha river, the Erai and the Wainganga river courses. It also contains gravel along with sand, silt and clays at places (Figure 2) (Satapathy, 2009).
Chandrapur district is underlined by various geological formations of Archaean to recent age. The Archaeans comprises hard and fissured gneisses, quartzite. The Vindhayans metasediments are represented by flaggy and massive shale, limestone, sandstones and ferruginous quartzite, covering an area of 1670 sq km. Groundwater in Archaean crystallites and Vindhayan rocks occurs under table to semi-confined conditions in weathered and fractured zones. Aquifers in Archaeans are characterized by degree of weathering, secondary porosity and effective inter-granular space; whereas in Vindhayans, joint planes and fracture porosity developed during cooling and compression of sediments and in limestone the solution cavities play a major role in aquifer nature. The geological setting of the Chandrapur district is as depicted in Table 1 (Geology of the Chandrapur).
The Chandrapur district is occupied by a host of geological formation ranging from Archaean to recent alluvium. The formations exposed in the order of antiquity are Archaean gneisses, Sakoli group of schists, Vindhyans, Gondwanas, Lametas, Deccan Traps and Laterite and alluvial deposits. The granites and gneisses of the Archaean complex occupy the largest area of the district in the central and eastern parts. Schists, phyllites, quartzites of the Sakoli group occur in small areas. Granite intrusive is seen in the eastern part (Geology of the Chandrapur). Limestone, quartzite and shale of the Vindhyan Super group occur as isolated out crops in south and south-western parts of the district. Sandstones, shale’s, clays of the Gondawana formations occur near Chandrapur city and also at other localities in isolated patches (Satapathy, 2009). Land use and land cover from the district is depicted in Figure 4.
Manganese ore deposits of Maharashtra are one of the remarkable in the world. They associated with the Pre-Cambrain metasediments. These manganese deposits are associated with spessartite-quartz rocks called “Gondite Series” by Fermor, after the Gonds. Other rocks are spessartite rocks, rhodonite rock, and rhodonite-quartz rocks, sometimes admixed with manganese amphibole and pyroxenes. The ore bodies are generally banded granutite-quartizite rocks, consisting of alternating bonds of manganese oxide, and dark maganiferous quartizite or chert, similar to BHO (Manganese ore, 2000).
The district is bestowed with deposits of various minerals like coal, iron, limestone, clay, copper, chromium, etc. Thermal power plant, many coal mines, cement and paper factories, huge limestone deposits, iron, and chromite mines are the sources of wealth for the district. Natural deposits of the high-grade iron ore in Sindewahi taluka are estimated to be 2,200,000 tonnes; limestone in Rajura and Korpana talukas (547,000,000 tonnes). Coal in Chandrapur taluka alone is estimated to be 1,227,000,000 tonnes. Availability of huge coal deposits has led to increased coal mining activity and the power plant. Availability of limestone has prompted cement industries particularly in Rajura tehsil. Paper mills are established because of availability of wood/bamboo located on banks of river or nallas (Satapathy, 2009).
Wardha, Wainganga and Penganga are the important rivers in Chandrapur district. The total replenishable groundwater resource is of the order of 3.782 x 1010 m3/year provision for domestic, industrial and other uses 1.24 x 1010 m3/year. Available groundwater resource for irrigation is 2.547 x 1010 m3/year and the net draft is 3.8 x 1010 m3 /year (Satapathy, 2009).
MATERIAL AND METHODS
Total 36 representative groundwater samples from hand pumps and dug wells from various villages of Chandrapur district were collected in a pre-cleaned, dry, 100 mL capacity polythene bottles (Poly lab, India). Groundwater sampling was carried out by grab sampling method for winter 2012. Out of these 36 groundwater samples collected in study area, two were from dug wells and remaining 34 from hand pumps. The selection of hand pumps/dug wells from study area was based on the basis of its usability by inhabitants, socio-economic conditions, topography and water sources. Before collecting water sample from hand pumps they were pumped for five minutes to avoid stagnation of sampling water in its internal pipe. At the time of allowing the water to flow from a hand pump, internal pipe structure of its outlet was cleaned so as to remove any solids or foreign material adhered to its internal surface.
Groundwater samples were collected in pre-cleaned, 100 mL plastic bottles which were thoroughly cleaned with dilute HNO3 followed by repeated washing with deionised water in the laboratory. The plastic bottles were rinsed with hand pump or dug well water before water sampling and then water sample was collected into it. Groundwater sample was collected up to rim of sampling bottle so as to have no head space in bottle for entry of atmospheric gases into it and thus altering its physico-chemical properties. While carrying out groundwater sampling, water sample was preserved by adding conc. HNO3 (1 mL for 100 mL water sample) into it. The sampling bottle’s mouth was closed with a screw cap which was afterwards sealed with the help of an adhesive tape so as to avoid entry of contaminant into it. The details regarding sampling location were recorded on sampling bottle and in field diary. The groundwater samples were brought to the laboratory for further analysis. Relevant data with respect to hand pump/dug well depth, year of installation, usability for drinking, availability of water throughout the year were also collected from individuals of respective house/localities.
Water quality parameters such as pH and conductivity were measured in field by using portable water analysis kit (Deluxe Water and Soil Analysis Kit, Model 172, India) and temperature by mercury thermometer (Gera Model, GTI, India). Groundwater manganese concentration was determined by using ICP-OES (ICP-OES, Dv 7000, Perkin Elmer, Germany).
While carrying out water sampling in study area relevant data with respect to hand pump/dug well depth, year of installation, usability, availability of water were also collected from respective villagers. The respondent includes males and females in study area having primary or above educational background. The age of the individuals who were interviewed was above 18 years. The data collected from this survey was utilized for groundwater manganese exposure analysis (Table 3).
The data obtained from analytical results was statistically analysed by employing various statistical tools which includes average, mode, median, range and standard deviation using Microsoft Excel, Origin and SPSS.
RESULTS AND DISCUSSION
Groundwater inventory from the study area is presented in Table 3. Details include groundwater availability throughout year, tap water availability, population of the village and use of groundwater for drinking purposes. Groundwater sampling locations, altitude (m amsl), water source, age of installation, depth in ft bgl (approx.) and manganese concentration in study area is presented in Table 4.
Table 5 summarises dug well/hand pump and water characteristics in study area. It was found that average year of installation of water source was 15.27 years; depth of water source (ft bgl) was 133.9 ft. This shows that maximum water source falls under the category of deep water source (100-150 ft bgl). The altitude in study area ranges from 152 m amsl to 287 m amsl with average of 214.5 m amsl. Average pH of groundwater was 6.98 and ranges from 5.97 to 7.56. Average pH indicates that water was near neutral nature and ranges from slightly acidic to slightly alkaline in nature. Groundwater temperature was in the range of 27.5 oC-31.5 oC with average temperature of 29.8 oC. Groundwater manganese concentration in study area was 0.20 mg/L with range from 0.001 mg/L to 1.85 mg/L.
Statistical summary of groundwater quality in study area is depicted in Table 6. Standard deviation of groundwater manganese was ±0.36. This shows that there is less deviation in manganese concentration in study area. The 98th percentile value for groundwater manganese from study area was 1.23 mg/L. The average groundwater pH was 6.98 with SD of ±0.31. From pH observations it can be concluded that groundwater pH was in narrow range. The 98th percentile value for pH was 7.56. Average EC was 1698±1055 mMHOS/cm. Higher values of SD for EC shows variation was significant in study area. The 98th percentile value was 4495 mMHOS/cm.
A comparison of manganese in groundwater at different EC and pH levels are presented in Table 7. Twelve samples had EC <1000 mMHOS/cm and 24 samples >1000 mMHOS/cm. Minimum EC of 255 mMHOS/cm at 6.95 pH had manganese concentration of 0.208 mg/L, whereas at EC of 4880 mMHOS/cm at 7.08 pH manganese concentration was 0.281 mg/L. No correlation was observed between EC, pH and manganese concentration in groundwater.
In Table 8, distribution pattern of manganese with depth of groundwater is reported. From table it was found that average manganese concentration increases as depth increases. Maximum average manganese concentration was reported from the depth of 300 ft, whereas as minimum average manganese concentration of 0.02 mg/L from 250 ft bgl. However, there can be exception for this as number of samples from this depth is two. Maximum average manganese concentration at 300 ft bgl shows that deeper earth crust had more minerals than upper one and thus had more concentration.
Percent distribution of well samples in study area for shallow (<100 ft bgl) and deep well (> 100 ft bgl) is presented in Table 9. From the table it can be seen that, 29 samples had groundwater manganese in the range of 0.1-0.3 mg/L. Out of these samples, 14 samples were in shallow well and 15 samples in deep well. In deep well samples presence of manganese was higher (41.65%) than shallow well (38.88%). Groundwater manganese concentration >0.3 mg/L was found in seven samples. Out of these four samples were in shallow well and three samples in deep well.
Table 10 compares Indian Standards for drinking water for acceptable and permissible limit with manganese concentration in study area. It was found that minimum manganese concentration in study area was 0.001 mg/L and maximum of 1.85 mg/L. The average manganese concentration was 0.20 mg/L. Percentage of samples exceeding acceptable limit of 0.1 mg/L was 38.88% whereas, for permissible limit of 0.3 mg/L was 19.44%.
Compliance of groundwater quality to drinking water standard is presented in Table 11. Shallow wells (<100 ft bgl, n=18) had minimum manganese concentration of 0.001 mg/L, maximum of 0.97 mg/L and average concentration was found to be 0.16 mg/L. Whereas in deep well (100-150 ft bgl, n=7) minimum manganese concentration was found to be 0.001 mg/L and maximum of 1.85 mg/L with average concentration of 0.36 mg/L. In very deep well (150-300 ft bgl, n=11) minimum manganese concentration was 0.001 mg/L, maximum of 0.79 mg/L and average of 0.14 mg/L.
Pearson correlation coefficient between water quality parameters from the study area is presented in Table 12. It was observed that groundwater manganese was positively correlated with chlorides, temperature, TDS, total hardness, EC, total alkalinity and iron; whereas negatively correlated with pH. Correlation with chlorides may be due to formation of different types of species with manganese present in groundwater in earth crust.
The Principal Component Analysis results for heavy metals content are presented in Table 13. Heavy metals are grouped into two component model, which accounted for 54% of all the data variation.
Groundwater manganese concentration vs. average concentration (0.2 mg/L) is depicted in Figure 8. It was observed that 10 samples had groundwater manganese concentration above average standard from study area. Maximum concentration above 1.85 mg/L followed by 0.97 and 0.79 mg/L were observed. Figure 9 depicts frequency distribution of manganese concentration in groundwater. From the figure it can be observed that 0.0015 mg/L manganese concentration was observed at eight sampling locations can be assigned to the minimum detection limit of the instrument for this particular parameter.
Comparison of groundwater manganese concentration vs. Indian Standard for drinking water is depicted in Figure 10. From the figure it can be seen that 22 samples were within acceptable limit of IS for drinking water for manganese (0.1 mg/L), whereas 29 samples within permissible limit (0.3 mg/L). Seven samples above permissible levels were observed in the study area.
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- Rahul Kamble (Author), 2017, Spatial Distribution of Groundwater Manganese in Central India, Munich, GRIN Verlag, https://www.grin.com/document/382048