Geoelectrical survey was carried out in the western delta region of River Vasista Godavari, Andhr... more Geoelectrical survey was carried out in the western delta region of River Vasista Godavari, Andhra Pradesh, India, for delineation of groundwater prospective zones due to acute shortage of water supply for various purposes. Forty-six vertical electrical soundings (VES) were done, employing the Schlumberger configuration with a maximum AB/2 of 160 m. The interpreted results of VES show four to five layers with variable thicknesses, such as topsoil zone (1.5-3 m), clay zone (0.84-32 m), finer sand zone (2-72 m), medium to coarse sand zone (4 to 28.8 m) and clay zone (1.2-∞ m), indicating a multi-aquifer system. These results are corroborated with the known lithologs of the study area. Further, the resistivity is also compared with electrical conductivity (EC) of groundwater observed nearby shallow wells representing buried channel (BC), flood plain (FP) and coastal (C) zones, which indicate slightly brackish to brackish water (EC: 1470-6010 µS/cm), whereas the groundwater observed from deep wells shows the fresh (EC: 726-1380 µS/cm), fresh to brackish (EC: 1010 to 3250 µS/cm), and brackish water (EC: 3020 to 4170 µS/cm) located in BC, FP and C zones, respectively. This survey reveals the prospective aquifer zones with potable water at VES locations
Impacts of geogenic and anthropogenic sources change seriously quality of groundwater. Inferior g... more Impacts of geogenic and anthropogenic sources change seriously quality of groundwater. Inferior groundwater quality directly affects the human health, agricultural output and industrial sector. The aim of the present study is to evaluate the groundwater quality for drinking purpose and also to identify the pollutants responsible for variation of chemical quality of groundwater, using pollution index of groundwater (PIG). Groundwater samples collected from a rural part of Telangana State, India, were analyzed for pH, total dissolved solids (TDS), calcium (Ca 2+), magnesium (Mg 2+), sodium (Na +), potassium (K +), bicarbonate (HCO − 3), chloride (Cl −), sulfate (SO 2− 4), nitrate (NO − 3) and fluoride (F −). The groundwater is characterized by Na + and HCO − 3 ions. The values of TDS
A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to ... more A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to probe into the spatial controlling processes of groundwater contamination, using principal component analysis (PCA). The PCA transforms the chemical variables, pH, EC
The chemistry of groundwater in the coastal region between Chirala and Ongole of Andhra Pradesh, ... more The chemistry of groundwater in the coastal region between Chirala and Ongole of Andhra Pradesh, India shows pollution to varying extent. The relative contribution of ions in six zones divided based on TDS indicates unsuitability of groundwater here for drinking, irrigation and industrial use. The water is brackish except in first zone and further alkaline. TDS is less than 1,000 mg/L in first zone, while it is more in other zones. This classification of groundwater into zones is also investigated by hydrogeochemical facies, genetic classification, mechanisms of groundwater chemistry and geochemical signatures. Hydrogeochemical facies of Na ? [ Mg 2? [Ca 2? :HCO À 3 [ Cl-[ SO 2À 4 is observed from zone I, while that of Na ? [Mg 2? [Ca 2? :Cl-[ HCO À 3 [ SO 2À 4 from second to sixth zones. The genetic classification of groundwater in first and second zones is HCO À 3 type and supported by good drainage conditions, while zones III to VI belong to Clcategory evident from poor drainage scenario. The location of six zones on mechanisms of groundwater chemistry supports sluggish drainage conditions of second to six zones, while predominate rock-water interaction in first zone. The geochemical signatures (HCO À 3 :Cl-[ 1 and Na ? :Cl-\ 1) also endorse the pollution. The quantities of chemical species (Mg 2? , Na ? , K ? , HCO À 3 , Cl À , SO 2À 4 , NO À 3 and F À) and TDS in all zones are far greater than the stipulated limits for drinking. The United States Salinity Laboratory plots discriminated the suitability of groundwater in second to sixth zones for irrigation after only special soil treatment. Higher concentrations of TDS, HCO À 3 , Cland SO 2À 4 in all zones render it unsuitable for industry too. This information is crucial for public and civic authorities for taking up strategic management plan for preventing further deterioration of hydrogeochemical environmental conditions of this part of the coastal region.
A survey on quality of groundwater was carried out for assessing the geochemical characteristics ... more A survey on quality of groundwater was carried out for assessing the geochemical characteristics and controlling factors of chemical composition of groundwater in a part of Guntur district, Andhra Pradesh, India, where the area is underlain by Peninsular Gneissic Complex. The results of the groundwater chemistry show a variation in pH, EC, TDS, Ca 2? , Mg 2? , Na ? , K ? , HCO 3-, Cl-, SO 4 2-, NO 3 and F-. The chemical composition of groundwater is mainly characterized by Na ?-HCO 3 facies. Hydrogeochemical type transits from Na ?-Cl-HCO 3 to Na ?-HCO 3-Clalong the flow path. Graphical and binary diagrams, correlation coefficients and saturation indices clearly explain that the chemical composition of groundwater is mainly controlled by geogenic processes (rock weathering, mineral dissolution, ion exchange and evaporation) and anthropogenic sources (irrigation return flow, wastewater, agrochemicals and constructional activities). The principal component (PC) analysis transforms the chemical variables into four PCs, which account for 87% of the total variance of the groundwater chemistry. The PC I has high positive loadings of pH, HCO 3-, NO 3-, K ? , Mg 2? and F-, attributing to mineral weathering and dissolution, and agrochemicals (nitrogen, phosphate and potash fertilizers). The PC II loadings are highly positive for Na ? , TDS, Cland F-, representing the rock weathering, mineral dissolution, ion exchange, evaporation, irrigation return flow and phosphate fertilizers. The PC III shows high loading of Ca 2? , which is caused by mineral weathering and dissolution, and constructional activities. The PC IV has high positive loading of Mg 2? and SO 4 2-, measuring the mineral weathering and dissolution, and soil amendments. The spatial distribution of PC scores explains that the geogenic processes are the primary contributors and man-made activities are the secondary factors responsible for modifications of groundwater chemistry. Further, geochemical modeling of groundwater also clearly confirms the water-rock interactions with respect to the phases of calcite, dolomite, fluorite, halite, gypsum, K-feldspar, albite and CO 2 , which are the prime factors controlling the chemistry of groundwater, while the rate of reaction and intensity are influenced by climate and anthropogenic activities. The study helps as baseline information to assess the sources of factors controlling the chemical composition of groundwater and also in enhancing the groundwater quality management.
Quality of groundwater is assessed from a part of Prakasam district, Andhra Pradesh, India. Groun... more Quality of groundwater is assessed from a part of Prakasam district, Andhra Pradesh, India. Groundwater samples collected from thirty locations from the study area were analysed for pH, electrical conductivity (EC), total dissolved solids (TDS), calcium (Ca 2+), magnesium (Mg 2+), sodium (Na +), potassium (K +), bicarbonate (HCO − 3), chloride (Cl −), sulphate (SO 2− 4), nitrate (NO − 3) and fluoride (F −). The results of the chemical analysis indicate that the groundwater is alkaline in nature and are mainly characterized by Na +-HCO − 3 and Na +-Cl − facies. Groundwater chemistry reflects the dominance of rock weathering and is subsequently modified by human activities, which are supported by genetic geochemical evolution and hydrogeochemical relations. Further, the chemical parameters (pH, TDS, Ca 2+ , Mg 2+ , Na + , HCO − 3 , Cl − , SO 2− 4 , NO − 3 and F −) were compared with the drinking water quality standards. The sodium adsorption ratio, percent sodium, permeability index, residual sodium carbonate, magnesium ratio and Kelly's ratio were computed and USSL, Wilcox and Doneen's diagrams were also used for evaluation of groundwater quality for irrigation. For industrial purpose, the pH, TDS, HCO − 3 , Cl − and SO 2− 4 were used to assess the impact of incrustation and corrosion activities on metal surfaces. As a whole, it is observed that the groundwater quality is not suitable for drinking, irrigation and industrial purposes due to one or more chemical parameters exceeding their standard limits. Therefore, groundwater management measures were suggested to improve the water quality.
The present study on geochemical evolution of groundwater is taken up to assess the controlling p... more The present study on geochemical evolution of groundwater is taken up to assess the controlling processes of water chemistry in the Western Delta region of the River Godavari (Andhra Pradesh), which is one of the major riceproducing centers in India. The study region is underlain by coarse sand with black clay (buried channels), black silty clay of recent origin (floodplain) and gray/white fine sand of modern beach sediment of marine source (coastal zone), including brown silty clay with fine sand (paleo-beach ridges). Groundwater is mostly brackish and very hard. It is characterized by Na ? [ Mg 2? [ Ca 2? :HCO 3-[ Cl-[ SO 4 2-[ NO 3-, Na ? [ Mg 2? [ Ca 2? :Cl-[ HCO 3-[ SO 4 2-, and Mg 2? [ Na ? [ Ca 2? [ or \ K ? :HCO 3-[ Cl-[ or [ SO 4 2facies. The ionic relations (Ca 2? ? Mg 2? :HCO 3-, Ca 2? ? Mg 2? :SO 4 2-? HCO 3-, Na ? ? K ? :TC, Na ? ? K ? :Cl-? SO 4 2-, HCO 3-:TC, HCO 3-: Ca 2? ? Mg 2? , Na ? :Cland Na ? :Ca 2?) indicate that the rock weathering, mineral dissolution, evaporation and ion exchange are the processes to control the aquifer chemistry. Anthropogenic and marine sources are also the supplementary factors for brackish water quality. These observations are further supported by Gibbs mechanisms that control the water chemistry. Thus, the study suggests that the initial quality of groundwater of geogenic origin has been subsequently modified by the influences of anthropogenic and marine sources.
Fractionation of methanolic extracts of air dried aerial parts of Parthenium resulted in the isol... more Fractionation of methanolic extracts of air dried aerial parts of Parthenium resulted in the isolation of a toxic constituent which was identified as parthenin, the major sesquiterpene lactone from the weed. The LD 50 (minimal lethal dose required to cause 50% mortality) for parthenin in rats was 42 mg/kg body weight. When [ 3 H]-parthenin was given orally or by intravenous administration, radioactivity appeared in the milk of lactating laboratory and dairy animals. Tissue distribution of radioactivity revealed that maximum label was detectable in kidneys.
The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal... more The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal variation of groundwater quality on irrigation and human health, where the agriculture is the main livelihood of rural people and the groundwater is the main source for irrigation and drinking. Granite gneisses associated with schists and charnockites of the Precambrian Eastern Ghats underlie the area. Groundwater samples collected seasonally, pre-and post-monsoons, during three years from forty wells in the area were analyzed for pH, EC, TDS, TA, TH, Ca 2+ , Mg 2+ , Na + , K + , CO 3 2) , HCO 3) , Cl) , SO 4 2) , NO 3) and F). The chemical relationships in Piper's diagram, Chebotarev's genetic classification and Gibbs's diagram suggest that the groundwaters mainly belong to noncarbonate alkali type and Cl) group, and are controlled by evaporationdominance, respectively, due to the influence of semi-arid climate, gentle slope, sluggish drainage conditions, greater water-rock interaction, and anthropogenic activities. A comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking, especially in post-monsoon period. US Salinity Laboratory's and Wilcox's diagrams, and %Na + used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation in postmonsoon compared to that in premonsoon. These conditions are caused due to leaching of salts from the overlying materials by infiltrating recharge waters. A management plan is suggested for sustainable development of the area.
In the online version in the second paragraph below the heading ''Factors controlling groundwater... more In the online version in the second paragraph below the heading ''Factors controlling groundwater quality'' and in the print version on page 548, 2nd column, 2nd paragraph, the first sentence should read: Though the groundwater samples 1, 2, 3, 12 and 19 show both fresh, TDS <1,000 mg/l, (sample 12) and brackish, TDS >1,000 mg/l, (samples 1-3 and 19) categories (Table 1), the ratios of Ca 2+ :Mg 2+ <1 (sample 19), TA:TH <1 (samples 1-3 and 12) and Cl-:HCO 3->1 (samples 1-3 and 12) in groundwaters (Table 3) suggest the influence of seawater.
Geochemical variations observed between shallow aquifer waters (SAW) and deeper aquifer waters (D... more Geochemical variations observed between shallow aquifer waters (SAW) and deeper aquifer waters (DAW) indicate better quality in DAW. Introduction: Groundwaters in crystalline terrains generally occur in environments of a weathered zone at shallow depth and in a fractured zone at deeper levels. Hydrogeologically, Visakhapatnam area, Andhra Pradesh is one such terrain. Studies indicate geochemical variations in the groundwaters of dugwells and borewells, which correspond to shallow and deeper aquifers , respectively. This paper presents hydrogeochemical data for shallow and deeper aquifers, the factors controlling the hydrogeochemical zoning, and potability for drinking purpose. Hydrogeology: The study area falls within the Eastern Ghats Mobile Belt, consisting of khondalites , with minor intrusives of charnockites. Rocks are distinctly gneissose in texture, medium to coarse-grained and made up of quartz, feldspar, garnet and sillimanite with or without biotite. They are subjected to two phases of folding and have a NE-SW foliation trend with dip of 70° to 80° SE (Fig. I).
Fluoride (F −) is essential for normal bone growth, but its higher concentration in the drinking ... more Fluoride (F −) is essential for normal bone growth, but its higher concentration in the drinking water poses great health problems and fluorosis is common in many parts of India. The present paper deals with the aim of establishment of facts of the chemical characteristics responsible for the higher concentration of F − in the groundwater, after understanding the chemical behavior of F − in relation to pH, total alkalinity (TA), total hardness (TH), carbonate hardness (CH), non-carbonate hardness (NCH), and excess alkalinity (EA) in the groundwater observed from the known areas of endemic fluorosis zones of Andhra Pradesh that have abundant sources of F −-bearing minerals of the Precambrians. The chemical data of the groundwater shows that the pH increases with increase F − ; the concentration of TH is more than the concentration of TA at low F − groundwater, the resulting water is represented by NCH; the TH has less concentration compared to TA at high F − groundwater, causing the water that is characterized by EA; and the water of both low and high concentrations of F − has CH. As a result, the F − has a positive
Fluoride (F-) content varies from 0.60 to 1.80 mg/L in the coastal region between Chirala and Ong... more Fluoride (F-) content varies from 0.60 to 1.80 mg/L in the coastal region between Chirala and Ongole of Andhra Pradesh, India. It exceeds the threshold limit of 1.20 mg/L in 20 % of the total groundwater samples. The aim of the present study is to assess the controlling factors of Fcontent. The study area experiences a dry climate and is underlain by Charnockite Group of rocks over which the river and coastal alluvium occur. The results of the study identify the four factors that control the high Fcontent. First one is related to alkalinity, leading to active dissolution and leaching of F-bearing minerals, which supports the positive correlation of Fwith pH and HCO 3-. A longer water residence time in the clays is the second factor, which activates not only solubility and dissolution of F-bearing minerals, but also anion exchange between Fand OH-. Third factor is a result of higher Na ? due to impact of saline water, ion exchange between Na ? and Ca 2? , and precipitation of CaCO 3. This reduces the Ca 2? content, causing dissolution of CaF 2 to maintain the chemical equilibria, which is supported by positive correlation between Na 2? and F-. The influence of anthropogenic activities is the last factor, which acts as an additional source of F-. Thus, the shallow groundwater shows higher content of Fand the hydrogeochemical facies also support this hypothesis. The study suggests the remedial measures to reduce the Fcontent.
Trace elements are essential for human health. However, excess concentrations of these elements c... more Trace elements are essential for human health. However, excess concentrations of these elements cause health disorders. A study has been carried out in Visakhapatnam environs, Andhra Pradesh, India to ascertain the causes for the origin and distribution of iron content in the groundwaters. Fifty groundwater samples are collected and analyzed for iron. The content of iron ranges from 400 to 780 μg/l. A comparison of groundwater data with rock and soil chemistry suggests that the concentration of iron (400-530 μg/l) in the groundwaters is derived from the rocks and soils due to geogenic processes. This concentration is taken as a natural occurrence of iron in the groundwaters of the study area for assessing the causes for its next higher content (>530 μg/l). Relatively higher concentration of iron (540-550 μg/l) is observed at some well waters, where the wells are located nearby municipal wastewaters, while the very high concentration of iron (610-780 μg/l) is observed in the industrially polluted groundwater zones, indicating the impact of anthropogenic activities on the groundwater system. These activities mask the concentration of iron caused by geogenic origin. Hence, both the geogenic and anthropogenic activities degrade the groundwater quality. Drinking water standards indicate that the iron content in all the groundwater samples exceeds the permissible limit (300 μg/l) recommended for drinking purpose, causing the health disorders. Necessity of close monitoring of groundwater quality for assessing the impact of geogenic and anthropogenic sources with reference to land use/land cover activities is emphasized in the present study area to protect the groundwater resources from the pollution.
Hydrogeological investigations have been carried out in rural parts of Guntur district, Andhra Pr... more Hydrogeological investigations have been carried out in rural parts of Guntur district, Andhra Pradesh, India where agriculture is the main occupation. Granite gneisses associated with schists and charnockites are the main lithological formations, which are overlain by black cotton soils. Groundwaters are alkaline, very hard and mostly brackish. Possible sources of fluoride (F-) are weathering and leaching of F-bearing minerals under the alkaline environment. A high rate of evapotranspiration, longer residence time of waters in the aquifer zone, intensive and longterm irrigation, and heavy use of fertilizers are the supplementary factors to further increase the Fcontent in the groundwaters. The investigated area has been classified into three types with reference to concentration of Fprescribed for drinking: low-F-(<0.60 mg l-1), moderate-F-(0.60-1.20 mg l-1) and high-F-(>1.20 mg l-1). Forty-five percent of the total groundwater samples belong to the high-Fcategory. Dental fluorosis is noticed in the region. A groundwater management programme is suggested.
The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal... more The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal variation of groundwater quality on irrigation and human health, where the agriculture is the main livelihood of rural people and the groundwater is the main source for irrigation and drinking. Granite gneisses associated with schists and charnockites of the Precambrian Eastern Ghats underlie the area. Groundwater samples collected seasonally, pre-and post-monsoons, during three years from forty wells in the area were analyzed for pH, EC, TDS, TA, TH, Ca 2+ , Mg 2+ , Na + , K + , CO 3 2) , HCO 3) , Cl) , SO 4 2) , NO 3) and F). The chemical relationships in Piper's diagram, Chebotarev's genetic classification and Gibbs's diagram suggest that the groundwaters mainly belong to noncarbonate alkali type and Cl) group, and are controlled by evaporationdominance, respectively, due to the influence of semi-arid climate, gentle slope, sluggish drainage conditions, greater water-rock interaction, and anthropogenic activities. A comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking, especially in post-monsoon period. US Salinity Laboratory's and Wilcox's diagrams, and %Na + used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation in postmonsoon compared to that in premonsoon. These conditions are caused due to leaching of salts from the overlying materials by infiltrating recharge waters. A management plan is suggested for sustainable development of the area.
Excess intake of fluoride through drinking water causes fluorosis on human beings in many States ... more Excess intake of fluoride through drinking water causes fluorosis on human beings in many States of the country (India), including Andhra Pradesh. Groundwater quality in the Varaha River Basin located in the Visakhapatnam District of Andhra Pradesh has been studied, with reference to fluoride content, for its possible sources for implementing appropriate management measures, according to the controlling mechanism of fluoride concentration in the groundwater. The area occupied by the river basin is underlain by the Precambrian Eastern Ghats, over which the Recent sediments occur. Results of the chemical data of the groundwater suggest that the considerable number of groundwater samples show fluoride content greater than that of the safe limit prescribed for drinking purpose. Statistical analysis shows that the fluoride has a good positive relation, with pH and bicarbonate. This indicates an alkaline environment, as a dominant controlling mechanism for leaching of fluoride from the source material. Other supplementary factors responsible for the occurrence of fluoride in the groundwater are evapotranspiration, long contact time of water with the aquifer material, and agricultural fertilizers. A lack of correlation between fluoride and chloride, and a high positive correlation between fluoride and bicarbonate indicate recharge of the aquifer by the river water. However, the higher concentration of fluoride observed in the groundwater in some locations indicates insufficient dilution by the river water. That means the natural dilution did not perform more effectively. Hence, the study emphasizes the need for surface water management structures, with people&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s participation, for getting more effective results.
Geoelectrical survey was carried out in the western delta region of River Vasista Godavari, Andhr... more Geoelectrical survey was carried out in the western delta region of River Vasista Godavari, Andhra Pradesh, India, for delineation of groundwater prospective zones due to acute shortage of water supply for various purposes. Forty-six vertical electrical soundings (VES) were done, employing the Schlumberger configuration with a maximum AB/2 of 160 m. The interpreted results of VES show four to five layers with variable thicknesses, such as topsoil zone (1.5-3 m), clay zone (0.84-32 m), finer sand zone (2-72 m), medium to coarse sand zone (4 to 28.8 m) and clay zone (1.2-∞ m), indicating a multi-aquifer system. These results are corroborated with the known lithologs of the study area. Further, the resistivity is also compared with electrical conductivity (EC) of groundwater observed nearby shallow wells representing buried channel (BC), flood plain (FP) and coastal (C) zones, which indicate slightly brackish to brackish water (EC: 1470-6010 µS/cm), whereas the groundwater observed from deep wells shows the fresh (EC: 726-1380 µS/cm), fresh to brackish (EC: 1010 to 3250 µS/cm), and brackish water (EC: 3020 to 4170 µS/cm) located in BC, FP and C zones, respectively. This survey reveals the prospective aquifer zones with potable water at VES locations
Impacts of geogenic and anthropogenic sources change seriously quality of groundwater. Inferior g... more Impacts of geogenic and anthropogenic sources change seriously quality of groundwater. Inferior groundwater quality directly affects the human health, agricultural output and industrial sector. The aim of the present study is to evaluate the groundwater quality for drinking purpose and also to identify the pollutants responsible for variation of chemical quality of groundwater, using pollution index of groundwater (PIG). Groundwater samples collected from a rural part of Telangana State, India, were analyzed for pH, total dissolved solids (TDS), calcium (Ca 2+), magnesium (Mg 2+), sodium (Na +), potassium (K +), bicarbonate (HCO − 3), chloride (Cl −), sulfate (SO 2− 4), nitrate (NO − 3) and fluoride (F −). The groundwater is characterized by Na + and HCO − 3 ions. The values of TDS
A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to ... more A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to probe into the spatial controlling processes of groundwater contamination, using principal component analysis (PCA). The PCA transforms the chemical variables, pH, EC
The chemistry of groundwater in the coastal region between Chirala and Ongole of Andhra Pradesh, ... more The chemistry of groundwater in the coastal region between Chirala and Ongole of Andhra Pradesh, India shows pollution to varying extent. The relative contribution of ions in six zones divided based on TDS indicates unsuitability of groundwater here for drinking, irrigation and industrial use. The water is brackish except in first zone and further alkaline. TDS is less than 1,000 mg/L in first zone, while it is more in other zones. This classification of groundwater into zones is also investigated by hydrogeochemical facies, genetic classification, mechanisms of groundwater chemistry and geochemical signatures. Hydrogeochemical facies of Na ? [ Mg 2? [Ca 2? :HCO À 3 [ Cl-[ SO 2À 4 is observed from zone I, while that of Na ? [Mg 2? [Ca 2? :Cl-[ HCO À 3 [ SO 2À 4 from second to sixth zones. The genetic classification of groundwater in first and second zones is HCO À 3 type and supported by good drainage conditions, while zones III to VI belong to Clcategory evident from poor drainage scenario. The location of six zones on mechanisms of groundwater chemistry supports sluggish drainage conditions of second to six zones, while predominate rock-water interaction in first zone. The geochemical signatures (HCO À 3 :Cl-[ 1 and Na ? :Cl-\ 1) also endorse the pollution. The quantities of chemical species (Mg 2? , Na ? , K ? , HCO À 3 , Cl À , SO 2À 4 , NO À 3 and F À) and TDS in all zones are far greater than the stipulated limits for drinking. The United States Salinity Laboratory plots discriminated the suitability of groundwater in second to sixth zones for irrigation after only special soil treatment. Higher concentrations of TDS, HCO À 3 , Cland SO 2À 4 in all zones render it unsuitable for industry too. This information is crucial for public and civic authorities for taking up strategic management plan for preventing further deterioration of hydrogeochemical environmental conditions of this part of the coastal region.
A survey on quality of groundwater was carried out for assessing the geochemical characteristics ... more A survey on quality of groundwater was carried out for assessing the geochemical characteristics and controlling factors of chemical composition of groundwater in a part of Guntur district, Andhra Pradesh, India, where the area is underlain by Peninsular Gneissic Complex. The results of the groundwater chemistry show a variation in pH, EC, TDS, Ca 2? , Mg 2? , Na ? , K ? , HCO 3-, Cl-, SO 4 2-, NO 3 and F-. The chemical composition of groundwater is mainly characterized by Na ?-HCO 3 facies. Hydrogeochemical type transits from Na ?-Cl-HCO 3 to Na ?-HCO 3-Clalong the flow path. Graphical and binary diagrams, correlation coefficients and saturation indices clearly explain that the chemical composition of groundwater is mainly controlled by geogenic processes (rock weathering, mineral dissolution, ion exchange and evaporation) and anthropogenic sources (irrigation return flow, wastewater, agrochemicals and constructional activities). The principal component (PC) analysis transforms the chemical variables into four PCs, which account for 87% of the total variance of the groundwater chemistry. The PC I has high positive loadings of pH, HCO 3-, NO 3-, K ? , Mg 2? and F-, attributing to mineral weathering and dissolution, and agrochemicals (nitrogen, phosphate and potash fertilizers). The PC II loadings are highly positive for Na ? , TDS, Cland F-, representing the rock weathering, mineral dissolution, ion exchange, evaporation, irrigation return flow and phosphate fertilizers. The PC III shows high loading of Ca 2? , which is caused by mineral weathering and dissolution, and constructional activities. The PC IV has high positive loading of Mg 2? and SO 4 2-, measuring the mineral weathering and dissolution, and soil amendments. The spatial distribution of PC scores explains that the geogenic processes are the primary contributors and man-made activities are the secondary factors responsible for modifications of groundwater chemistry. Further, geochemical modeling of groundwater also clearly confirms the water-rock interactions with respect to the phases of calcite, dolomite, fluorite, halite, gypsum, K-feldspar, albite and CO 2 , which are the prime factors controlling the chemistry of groundwater, while the rate of reaction and intensity are influenced by climate and anthropogenic activities. The study helps as baseline information to assess the sources of factors controlling the chemical composition of groundwater and also in enhancing the groundwater quality management.
Quality of groundwater is assessed from a part of Prakasam district, Andhra Pradesh, India. Groun... more Quality of groundwater is assessed from a part of Prakasam district, Andhra Pradesh, India. Groundwater samples collected from thirty locations from the study area were analysed for pH, electrical conductivity (EC), total dissolved solids (TDS), calcium (Ca 2+), magnesium (Mg 2+), sodium (Na +), potassium (K +), bicarbonate (HCO − 3), chloride (Cl −), sulphate (SO 2− 4), nitrate (NO − 3) and fluoride (F −). The results of the chemical analysis indicate that the groundwater is alkaline in nature and are mainly characterized by Na +-HCO − 3 and Na +-Cl − facies. Groundwater chemistry reflects the dominance of rock weathering and is subsequently modified by human activities, which are supported by genetic geochemical evolution and hydrogeochemical relations. Further, the chemical parameters (pH, TDS, Ca 2+ , Mg 2+ , Na + , HCO − 3 , Cl − , SO 2− 4 , NO − 3 and F −) were compared with the drinking water quality standards. The sodium adsorption ratio, percent sodium, permeability index, residual sodium carbonate, magnesium ratio and Kelly's ratio were computed and USSL, Wilcox and Doneen's diagrams were also used for evaluation of groundwater quality for irrigation. For industrial purpose, the pH, TDS, HCO − 3 , Cl − and SO 2− 4 were used to assess the impact of incrustation and corrosion activities on metal surfaces. As a whole, it is observed that the groundwater quality is not suitable for drinking, irrigation and industrial purposes due to one or more chemical parameters exceeding their standard limits. Therefore, groundwater management measures were suggested to improve the water quality.
The present study on geochemical evolution of groundwater is taken up to assess the controlling p... more The present study on geochemical evolution of groundwater is taken up to assess the controlling processes of water chemistry in the Western Delta region of the River Godavari (Andhra Pradesh), which is one of the major riceproducing centers in India. The study region is underlain by coarse sand with black clay (buried channels), black silty clay of recent origin (floodplain) and gray/white fine sand of modern beach sediment of marine source (coastal zone), including brown silty clay with fine sand (paleo-beach ridges). Groundwater is mostly brackish and very hard. It is characterized by Na ? [ Mg 2? [ Ca 2? :HCO 3-[ Cl-[ SO 4 2-[ NO 3-, Na ? [ Mg 2? [ Ca 2? :Cl-[ HCO 3-[ SO 4 2-, and Mg 2? [ Na ? [ Ca 2? [ or \ K ? :HCO 3-[ Cl-[ or [ SO 4 2facies. The ionic relations (Ca 2? ? Mg 2? :HCO 3-, Ca 2? ? Mg 2? :SO 4 2-? HCO 3-, Na ? ? K ? :TC, Na ? ? K ? :Cl-? SO 4 2-, HCO 3-:TC, HCO 3-: Ca 2? ? Mg 2? , Na ? :Cland Na ? :Ca 2?) indicate that the rock weathering, mineral dissolution, evaporation and ion exchange are the processes to control the aquifer chemistry. Anthropogenic and marine sources are also the supplementary factors for brackish water quality. These observations are further supported by Gibbs mechanisms that control the water chemistry. Thus, the study suggests that the initial quality of groundwater of geogenic origin has been subsequently modified by the influences of anthropogenic and marine sources.
Fractionation of methanolic extracts of air dried aerial parts of Parthenium resulted in the isol... more Fractionation of methanolic extracts of air dried aerial parts of Parthenium resulted in the isolation of a toxic constituent which was identified as parthenin, the major sesquiterpene lactone from the weed. The LD 50 (minimal lethal dose required to cause 50% mortality) for parthenin in rats was 42 mg/kg body weight. When [ 3 H]-parthenin was given orally or by intravenous administration, radioactivity appeared in the milk of lactating laboratory and dairy animals. Tissue distribution of radioactivity revealed that maximum label was detectable in kidneys.
The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal... more The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal variation of groundwater quality on irrigation and human health, where the agriculture is the main livelihood of rural people and the groundwater is the main source for irrigation and drinking. Granite gneisses associated with schists and charnockites of the Precambrian Eastern Ghats underlie the area. Groundwater samples collected seasonally, pre-and post-monsoons, during three years from forty wells in the area were analyzed for pH, EC, TDS, TA, TH, Ca 2+ , Mg 2+ , Na + , K + , CO 3 2) , HCO 3) , Cl) , SO 4 2) , NO 3) and F). The chemical relationships in Piper's diagram, Chebotarev's genetic classification and Gibbs's diagram suggest that the groundwaters mainly belong to noncarbonate alkali type and Cl) group, and are controlled by evaporationdominance, respectively, due to the influence of semi-arid climate, gentle slope, sluggish drainage conditions, greater water-rock interaction, and anthropogenic activities. A comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking, especially in post-monsoon period. US Salinity Laboratory's and Wilcox's diagrams, and %Na + used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation in postmonsoon compared to that in premonsoon. These conditions are caused due to leaching of salts from the overlying materials by infiltrating recharge waters. A management plan is suggested for sustainable development of the area.
In the online version in the second paragraph below the heading ''Factors controlling groundwater... more In the online version in the second paragraph below the heading ''Factors controlling groundwater quality'' and in the print version on page 548, 2nd column, 2nd paragraph, the first sentence should read: Though the groundwater samples 1, 2, 3, 12 and 19 show both fresh, TDS <1,000 mg/l, (sample 12) and brackish, TDS >1,000 mg/l, (samples 1-3 and 19) categories (Table 1), the ratios of Ca 2+ :Mg 2+ <1 (sample 19), TA:TH <1 (samples 1-3 and 12) and Cl-:HCO 3->1 (samples 1-3 and 12) in groundwaters (Table 3) suggest the influence of seawater.
Geochemical variations observed between shallow aquifer waters (SAW) and deeper aquifer waters (D... more Geochemical variations observed between shallow aquifer waters (SAW) and deeper aquifer waters (DAW) indicate better quality in DAW. Introduction: Groundwaters in crystalline terrains generally occur in environments of a weathered zone at shallow depth and in a fractured zone at deeper levels. Hydrogeologically, Visakhapatnam area, Andhra Pradesh is one such terrain. Studies indicate geochemical variations in the groundwaters of dugwells and borewells, which correspond to shallow and deeper aquifers , respectively. This paper presents hydrogeochemical data for shallow and deeper aquifers, the factors controlling the hydrogeochemical zoning, and potability for drinking purpose. Hydrogeology: The study area falls within the Eastern Ghats Mobile Belt, consisting of khondalites , with minor intrusives of charnockites. Rocks are distinctly gneissose in texture, medium to coarse-grained and made up of quartz, feldspar, garnet and sillimanite with or without biotite. They are subjected to two phases of folding and have a NE-SW foliation trend with dip of 70° to 80° SE (Fig. I).
Fluoride (F −) is essential for normal bone growth, but its higher concentration in the drinking ... more Fluoride (F −) is essential for normal bone growth, but its higher concentration in the drinking water poses great health problems and fluorosis is common in many parts of India. The present paper deals with the aim of establishment of facts of the chemical characteristics responsible for the higher concentration of F − in the groundwater, after understanding the chemical behavior of F − in relation to pH, total alkalinity (TA), total hardness (TH), carbonate hardness (CH), non-carbonate hardness (NCH), and excess alkalinity (EA) in the groundwater observed from the known areas of endemic fluorosis zones of Andhra Pradesh that have abundant sources of F −-bearing minerals of the Precambrians. The chemical data of the groundwater shows that the pH increases with increase F − ; the concentration of TH is more than the concentration of TA at low F − groundwater, the resulting water is represented by NCH; the TH has less concentration compared to TA at high F − groundwater, causing the water that is characterized by EA; and the water of both low and high concentrations of F − has CH. As a result, the F − has a positive
Fluoride (F-) content varies from 0.60 to 1.80 mg/L in the coastal region between Chirala and Ong... more Fluoride (F-) content varies from 0.60 to 1.80 mg/L in the coastal region between Chirala and Ongole of Andhra Pradesh, India. It exceeds the threshold limit of 1.20 mg/L in 20 % of the total groundwater samples. The aim of the present study is to assess the controlling factors of Fcontent. The study area experiences a dry climate and is underlain by Charnockite Group of rocks over which the river and coastal alluvium occur. The results of the study identify the four factors that control the high Fcontent. First one is related to alkalinity, leading to active dissolution and leaching of F-bearing minerals, which supports the positive correlation of Fwith pH and HCO 3-. A longer water residence time in the clays is the second factor, which activates not only solubility and dissolution of F-bearing minerals, but also anion exchange between Fand OH-. Third factor is a result of higher Na ? due to impact of saline water, ion exchange between Na ? and Ca 2? , and precipitation of CaCO 3. This reduces the Ca 2? content, causing dissolution of CaF 2 to maintain the chemical equilibria, which is supported by positive correlation between Na 2? and F-. The influence of anthropogenic activities is the last factor, which acts as an additional source of F-. Thus, the shallow groundwater shows higher content of Fand the hydrogeochemical facies also support this hypothesis. The study suggests the remedial measures to reduce the Fcontent.
Trace elements are essential for human health. However, excess concentrations of these elements c... more Trace elements are essential for human health. However, excess concentrations of these elements cause health disorders. A study has been carried out in Visakhapatnam environs, Andhra Pradesh, India to ascertain the causes for the origin and distribution of iron content in the groundwaters. Fifty groundwater samples are collected and analyzed for iron. The content of iron ranges from 400 to 780 μg/l. A comparison of groundwater data with rock and soil chemistry suggests that the concentration of iron (400-530 μg/l) in the groundwaters is derived from the rocks and soils due to geogenic processes. This concentration is taken as a natural occurrence of iron in the groundwaters of the study area for assessing the causes for its next higher content (>530 μg/l). Relatively higher concentration of iron (540-550 μg/l) is observed at some well waters, where the wells are located nearby municipal wastewaters, while the very high concentration of iron (610-780 μg/l) is observed in the industrially polluted groundwater zones, indicating the impact of anthropogenic activities on the groundwater system. These activities mask the concentration of iron caused by geogenic origin. Hence, both the geogenic and anthropogenic activities degrade the groundwater quality. Drinking water standards indicate that the iron content in all the groundwater samples exceeds the permissible limit (300 μg/l) recommended for drinking purpose, causing the health disorders. Necessity of close monitoring of groundwater quality for assessing the impact of geogenic and anthropogenic sources with reference to land use/land cover activities is emphasized in the present study area to protect the groundwater resources from the pollution.
Hydrogeological investigations have been carried out in rural parts of Guntur district, Andhra Pr... more Hydrogeological investigations have been carried out in rural parts of Guntur district, Andhra Pradesh, India where agriculture is the main occupation. Granite gneisses associated with schists and charnockites are the main lithological formations, which are overlain by black cotton soils. Groundwaters are alkaline, very hard and mostly brackish. Possible sources of fluoride (F-) are weathering and leaching of F-bearing minerals under the alkaline environment. A high rate of evapotranspiration, longer residence time of waters in the aquifer zone, intensive and longterm irrigation, and heavy use of fertilizers are the supplementary factors to further increase the Fcontent in the groundwaters. The investigated area has been classified into three types with reference to concentration of Fprescribed for drinking: low-F-(<0.60 mg l-1), moderate-F-(0.60-1.20 mg l-1) and high-F-(>1.20 mg l-1). Forty-five percent of the total groundwater samples belong to the high-Fcategory. Dental fluorosis is noticed in the region. A groundwater management programme is suggested.
The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal... more The area in Guntur district, Andhra Pradesh, India, is selected to discuss the impact of seasonal variation of groundwater quality on irrigation and human health, where the agriculture is the main livelihood of rural people and the groundwater is the main source for irrigation and drinking. Granite gneisses associated with schists and charnockites of the Precambrian Eastern Ghats underlie the area. Groundwater samples collected seasonally, pre-and post-monsoons, during three years from forty wells in the area were analyzed for pH, EC, TDS, TA, TH, Ca 2+ , Mg 2+ , Na + , K + , CO 3 2) , HCO 3) , Cl) , SO 4 2) , NO 3) and F). The chemical relationships in Piper's diagram, Chebotarev's genetic classification and Gibbs's diagram suggest that the groundwaters mainly belong to noncarbonate alkali type and Cl) group, and are controlled by evaporationdominance, respectively, due to the influence of semi-arid climate, gentle slope, sluggish drainage conditions, greater water-rock interaction, and anthropogenic activities. A comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking, especially in post-monsoon period. US Salinity Laboratory's and Wilcox's diagrams, and %Na + used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation in postmonsoon compared to that in premonsoon. These conditions are caused due to leaching of salts from the overlying materials by infiltrating recharge waters. A management plan is suggested for sustainable development of the area.
Excess intake of fluoride through drinking water causes fluorosis on human beings in many States ... more Excess intake of fluoride through drinking water causes fluorosis on human beings in many States of the country (India), including Andhra Pradesh. Groundwater quality in the Varaha River Basin located in the Visakhapatnam District of Andhra Pradesh has been studied, with reference to fluoride content, for its possible sources for implementing appropriate management measures, according to the controlling mechanism of fluoride concentration in the groundwater. The area occupied by the river basin is underlain by the Precambrian Eastern Ghats, over which the Recent sediments occur. Results of the chemical data of the groundwater suggest that the considerable number of groundwater samples show fluoride content greater than that of the safe limit prescribed for drinking purpose. Statistical analysis shows that the fluoride has a good positive relation, with pH and bicarbonate. This indicates an alkaline environment, as a dominant controlling mechanism for leaching of fluoride from the source material. Other supplementary factors responsible for the occurrence of fluoride in the groundwater are evapotranspiration, long contact time of water with the aquifer material, and agricultural fertilizers. A lack of correlation between fluoride and chloride, and a high positive correlation between fluoride and bicarbonate indicate recharge of the aquifer by the river water. However, the higher concentration of fluoride observed in the groundwater in some locations indicates insufficient dilution by the river water. That means the natural dilution did not perform more effectively. Hence, the study emphasizes the need for surface water management structures, with people&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s participation, for getting more effective results.
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