S. Basu Mallik

Jadavpur University, Calcutta, Bengal, India

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Publications (17)34.53 Total impact

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    ABSTRACT: This study aims at finding out possible relation between lithology and spatial pattern of dissolved arsenic (As) in groundwater around Chakdaha municipality, West Bengal, India. Satellite image, coupled with electrical resistivity survey and borehole drilling helps to delineate surface and sub-surface lithological framework of the As affected alluvial aquifers. The satellite imagery demonstrate that the high As area are presumably under active flood plain environment (low-lying areas), that constantly receive organics due to periodic flooding. Thick low resistive (fine-grained) layer was observed at the top around the high As areas, which, however, not found in low As areas. The result suggests that hydraulic properties of the surface/sub-surface soil/sediment have an important control on the fate and transport of As in the aquifer. This study demonstrates that electrical resistivity tools can be effectively used for the reconnaissance survey in characterizing the plausible lithological framework of an alluvial aquifer containing As. KeywordsBengal Delta Plain-Groundwater-Arsenic-Geomorphology-Electrical resistivity
    Environmental earth sciences 04/2009; 60(4):873-884. DOI:10.1007/s12665-009-0224-0 · 1.57 Impact Factor
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    ABSTRACT: Palaeomagnetic and magnetomineralogical results are reported from charnockites in basement terrane at the eastern sector of the WSW–ENE granulite belt of South India. Magnetite is the dominant ferromagnet identified by rock magnetic and optical study; it is present in several phases including large homogeneous titanomagnetites and disseminated magnetite in microfractures linked to growth stages ranging from primary charnockite formation to uplift decompression and exhumation within the interval ∼2500–2100 Ma. Several components of magnetization are resolved by thermal demagnetization and summarized by four pole positions; in the northern (Pallavaram) sector these are P1 (33°N, 99°E, dp/dm = 8/9°) and P2 (79°N, 170°E, dp/dm = 3/6°), and in the southern (Vandallur) sector they are V1 (23°N, 116°E, dp/dm = 8/9°) and V2 (26°S, 136°E, dp/dm = 5/10°). These magnetizations are linked to uplift cooling of the basement and unblocking temperature spectra suggest acquisition sequences P1 → P2 and V1 → V2 in each case implying movement of the shield from higher to lower palaeolatitudes sometime between 2500 and 2100 Ma. Palaeomagnetic poles from the cratonic nuclei of Africa, Australia and India all identify motion from higher to lower palaeolatitudes in Early Palaeoproterozoic times, and this is dated ∼2400 and ∼2200 Ma in the former two shields. The corresponding apparent polar wander (APW) segments match the magnetization record within the charnockite basement terranes of southern India to yield a preliminary reconstruction of the ‘Ur’ protocontinent, the oldest surviving continental protolith with origins prior to 3000 Ma. Although subject to later relative movements these nuclei seem to have remained in proximity until the Mesozoic break-up of Gondwana.
    Journal of Asian Earth Sciences 04/2009; 34(4):493-506. DOI:10.1016/j.jseaes.2008.08.004 · 2.83 Impact Factor
  • Applied Geochemistry 01/2009; 24(1):186-187. DOI:10.1016/j.apgeochem.2008.11.002 · 2.02 Impact Factor
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    ABSTRACT: Aquifer sediments from areas of low- and high-As groundwater were characterized mineralogically and geochemically at a field site in the Nadia district of West Bengal, India. Leaching experiments and selective extraction of the sediments were also carried out to understand the release mechanism of As in the sub-surface. The correlation between measured elements (major, minor and trace) from low- and high-As groundwater areas are only significant for As, Fe and Mn. The borehole lithology and percentage of silt and clay fraction demonstrates the dominance of finer sediments in the high-As aquifer. Multivariate analysis of the geochemical parameters showed the presence of four different mineral phases (heavy-mineral fraction, phyllosilicates/biotite/Fe-oxyhydroxides, carbonates and sulphides) in the sediments. Selective extraction of sediment reveals that amorphous Fe-oxyhydroxide acts as a potential sink for As in the sub-surface. The result is consistent with microbially mediated redox reactions, which are controlled in part by the presence of natural organic matter within the aquifer sediments. The occurrences of As-bearing redox traps, primarily formed of Fe- and Mn-oxides/hydroxides, are also important factors that control the release of As into groundwater at the study site.
    Applied Geochemistry 05/2008; 23(5):996-1011. DOI:10.1016/j.apgeochem.2007.11.017 · 2.02 Impact Factor
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    ABSTRACT: The present study demonstrates the importance of hydrogeochemical characteristics (groundwater flow and recharge) of an aquifer in the release of As to groundwater. The study area (∼20 km2) is located in Chakdaha block, Nadia district, West Bengal, which hosts groundwaters of variable As content. The spatial distribution pattern of As is patchy with areas containing groundwater that is high in As (>200 μg L−1) found in close vicinity to low As (<50 μg L−1) groundwaters (within 100 m). The concentration of groundwater As is found to decrease with depth. In addition, the data shows that there is no conspicuous relationship between high groundwater As concentration and high groundwater abstraction, although the central cone of depression has enlarged over 2 a and is extending towards the SE of the study area. The river Hooghly, which forms the NW boundary of the study site, shows dual behaviour (effluent and influent during pre- and post-monsoon periods, respectively), complicating the site hydrogeology. The observed groundwater flow lines tend to be deflected away from the high As portion of the aquifer, indicating that groundwater movement is very sluggish in the As-rich area. This leads to a high residence time for this groundwater package, prolonging sediment–water interaction, and hence facilitating groundwater As release.
    Applied Geochemistry 05/2008; 23(5):977-995. DOI:10.1016/j.apgeochem.2007.11.016 · 2.02 Impact Factor
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    ABSTRACT: The origin of the spatial variability of dissolved As concentrations in shallow aquifers of the Bengal Basin remains poorly understood. To address this, we compare here transects of simultaneously-collected groundwater and aquifer solids perpendicular to the banks of the Hooghly River in Chakdaha, India, and the Old Brahmaputra River in Araihazar, Bangladesh. Variations in surface geomorphology mapped by electromagnetic conductivity indicate that permeable sandy soils are associated with underlying aquifers that are moderately reducing to a depth of 10-30 m, as indicated by acid-leachable Fe(II)/Fe ratios <0.6 in the solid phase and concentrations of dissolved sulfate >5 mg L(-1). More reducing aquifers are typically capped with finer-grained soils. The patterns suggest that vertical recharge through permeable soils is associated with a flux of oxidants on the banks of the Hooghly River and, further inland, in both Chakdaha and Araihazar. Moderately reducing conditions maintained by local recharge are generally associated with low As concentrations in Araihazar, but not systematically so in Chakdaha. Unlike Araihazar, there is also little correspondence in Chakdaha between dissolved As concentrations in groundwater and the P-extractable As content of aquifer particles, averaging 191 +/- 122 microg As/L, 1.1 +/- 1.5 mg As kg(-1) (n = 43) and 108 +/- 31 microg As/L, 3.1 +/- 6.5 mg As kg(-1) (n = 60), respectively. We tentatively attribute these differences to a combination of younger floodplain sediments, and therefore possibly more than one mechanism of As release, as well as less reducing conditions in Chakdaha compared to Araihazar. Systematic dating of groundwater and sediment, combined with detailed mapping of the composition of aquifer solids and groundwater, will be needed to identify the various mechanisms underlying the complex distribution of As in aquifers of the Bengal Basin.
    Geochemical Transactions 01/2008; 9:1. DOI:10.1186/1467-4866-9-1 · 2.65 Impact Factor
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    ABSTRACT: To evaluate suggestions from earlier work that a reversal of magnetization is present in the Rajmahal Traps of mid-Cretaceous (probable Aptian) age in north-eastern India, we have sampled a 140 m thick section comprising a minimum of nine flow units at 25 sites in the north-western part of the outcrop. A coherent N→R→N magnetostratigraphy is identified, with evidence for transitional behaviour at the top and bottom of the succession.The mean characteristic remanence direction of the reversed sites (D/I= 145.7°/63.5°, α95= 6.0°) is approximately antiparallel to that of the normal polarity sites (D/I = 300.2°/-55.7°, α95= 12.4°), and the group mean confirms a palaeomagnetic pole position near 125°E, 9°S (A95= 10.5°) for the time of eruption of the traps. From 40Ar/39Ar evidence that the Rajmahal-Bengal Traps were emplaced over a short interval at ca, 117 Ma, we interpret the brief reversed episode identified near the base of the succession as a record of the JSEA event. The polarity evidence therefore supports the view that the Rajmahal Traps were fed by the Crozet Hotspot at the beginning of the Cretaceous Normal Superchron (∼ 119–83 Ma).
    Geophysical Journal International 08/2007; 124(2):427 - 432. DOI:10.1111/j.1365-246X.1996.tb07030.x · 2.72 Impact Factor
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    ABSTRACT: Extremely high As concentrations in drinking water of the Ganges Delta (West Bengal and Bangladesh) has emerged as an issue of great concern in the past decade because of its serious impact on the health of millions of people. The distribution pattern of As concentrations in the Ganges Delta region is patchy and there are numerous As “hotspots”. The present study is perhaps the first attempt in West Bengal to characterize such a hotspot by geophysical and geochemical methods, and to model the transport of the enrichment plume using a 1D reactive transport model (PHREEQC). The study site is located along the Hooghly River, 60 km north of Kolkota City, near the city of Chakdaha. Total As concentrations in the groundwater range from 0.5 to more than 6 μmol L−1; the WHO recommended maximum drinking water concentration is 0.13 μmol L−1 (i.e. 10 μg L−1). Results show groundwater is in chemical equilibrium with siderite and calcite, a mineral phase previously shown to be an efficient trap for As(III). Groundwater redox potential is controlled by the Fe(OH)3(am)/Fe2+ couple. The As(III) versus As(V) distribution (42% As(III) and 58% As(V), on average) is not at equilibrium with measured Eh values. No evidence of sulfide solid phases, such as As rich pyrite or arsenopyrite, was found. Although amorphous Fe dissolution is confirmed to play an important role in the release of As, selective dissolution extractions indicate that adsorption of As on carbonates and micas may also be an important component of As cycling in the sediment. Modelling results demonstrate the role of and Fe(II) in mobilizing the As plume, thereby increasing the threat to the 75,000 inhabitants of Chakdaha.
    Applied Geochemistry 07/2007; 22(7):1273-1292. DOI:10.1016/j.apgeochem.2006.12.022 · 2.02 Impact Factor
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    ABSTRACT: Possible relationships between groundwater arsenic concentration and alluvial sediment characteristics in a ~19 km2 area in West Bengal have been investigated using a combination of hydrogeochemical, lithogeochemical and geophysical techniques. Arsenic hotspots, typically associated with elevated groundwater Fe and Mn, were found to be correlated to some extent with old river channels (abandoned meanders, oxbow lakes), where sandy aquifers included intercalated fine-grained overbank deposits, rich in As, Fe, Mn and Corg. Otherwise no demonstrably significant overall differences in any of lithology, grain-size distribution, mineral composition or Fe, Mn and organic C content of the sediments were found between two representative sites with contrastingly low (<50 μg l−1) and high (>200 μg l−1) As groundwater contents. Our results are consistent with microbially mediated redox reactions controlled by the presence of natural organic matter within the aquifer and the occurrence of As-bearing redox traps, primarily formed by Fe and Mn oxides/hydroxides, being the most important factors which control the release of As into shallow groundwaters at the study site.
    Mineralogical Magazine 10/2005; 69(5):841-854. DOI:10.1180/0026461056950292 · 1.90 Impact Factor
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    ABSTRACT: Groundwater of the arsenic affected areas demonstrates that the water is Ca-bocarbonate type and typical anoxie in nature. High arsenic groundwater is distributed in patches and ``hot spots'' are identifie in palaeo-meander belt. Iron rich arsenic traps undergo reduction and release redox sensitive species (As and Fe) under local reducing conditions. Releases of redox species are often depends on land-use pattern and the abundance of bio-available fonns of iron oxides/minerals.
    Journal de Physique IV (Proceedings) 05/2003; 107:293-296. · 0.35 Impact Factor
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    ABSTRACT: This study has investigated palaeomagnetism and magnetic properties of a tract of continental basement in south India metamorphosed to granulite facies close to the Archaean–Proterozoic boundary (∼2600Ma) at former depths of 20–35km. The metamorphism is characterised by extensive development of charnockite produced by flushing of CO2-rich fluids through older crust. Rock magnetic studies (thermomagnetic, high and low temperature susceptibility, hysteresis and IRM) show that very low-Ti metamorphic magnetite is the ubiquitous ferromagnet in all rock types. It has predominantly multidomain characteristics but is of high magnetic stability probably due to exsolution precipitation and microfracture filling producing anisotropic grain shapes. Magnetic susceptibility shows little increase with temperature falling to zero at ∼550°C implying that induced magnetisation drops to a weak paramagnetic effect near this isotherm. Susceptibilities and intensities of magnetisation increase from amphibolite to granulite facies and by an order of magnitude within charnockites in the lower dehydrated crust. Induced magnetisations are able to explain ∼50% of observed magnetic anomalies of deep origin. Intensities of magnetisation and Qn values are high, especially in charnockite where metasomatism has resulted in new magnetite formation, and it is concluded this facies is able to explain observed magnetic anomalies provided that viscous remnant magnetisation is enhanced at depth to contribute the remaining magnetisation. The magnitude of anisotropy of magnetic susceptibility (AMS) is also increased by charnockite formation, as are degrees of lineation and foliation. However, directions of AMS in these anhydrous rocks are essentially random and reflect the static nature of the charnockite metasomatism.No appreciable Phanerozoic overprinting is evident in this terrane and the dominant feature of the palaeomagnetic record is a west to north shallow swathe of component directions with a minor antiparallel sequence between means summarised by A1 (D/I=280/−8°), A2 (D/I=319/−11°) and A3 (D/I=1/−10°). This swathe is interpreted as an uplift-related cooling acquisition following charnockite formation at ∼2600Ma and a remanence age of ∼2600–2400Ma is implied by the absence of most of the swathe in early Palaeoproterozoic and younger dyke swarms cutting the region. A second group of component directions (‘B’, mean D/I=238/−87°) is similar to magnetisations found in dykes linked to an age of ∼2370Ma and interpreted as somewhat younger than the ‘A’ swathe. We argue that the entire magnetic record was acquired before final basement uplift prior to 2000–1800Ma. Collective late Archaean–early Proterozoic palaeopoles from India define a low to high latitude movement of the shield at ∼2600–2300Ma which is replicated in contemporaneous results from the other ancient Gondwana nucleii of southern Africa and Australia. The cratonic nucleii of these three shields have the oldest laterally-extensive supracrustal covers and comprise the core of the protocontinent of ‘Ur’. The 2900–2200Ma palaeopoles are consistent with close proximities and subsequent movements between them were apparently limited because continental proximities, but not configurations, were similar within the (Palaeozoic) supercontinent of Gondwana.
    Precambrian Research 03/2003; 121(3):185-219. DOI:10.1016/S0301-9268(02)00224-3 · 6.02 Impact Factor
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    ABSTRACT: Arsenic contamination in drinking water is a problem of great concern in Ganges delta region, and could be one of the largest natural calamity in the world. In the present study, a contamination plume located in the Lalpur area (Chakdaha Block, Nadia District, West Bengal, India) was studied. A coupled geochemical and geophysical approach was employed to understand the mechanism of arsenic mobilisation from the sediments to groundwater, as a first step towards a global explanation of the phenomenon for other contaminated areas in the Ganges delta. The groundwater As concentration, in the 10 km x 10 km studied area, ranges from 10 to 500 ppb. In situ chemical speciation of arsenic was carried out and various geochemical parameters were measured in representative contaminated wells to interpret the mobilization mechanism in terms of redox kinetics. Through geophysical investigations, subsurface lithology, sediment depositional and geomorphological characteristics were determined and correlated with the arsenic contamination processes. From a geomorphological viewpoint, the contaminated area is located in an abandoned paleochannel of the Hooghly river, interpreted as the active site of deposition of fine sediments which were preserved as clay pockets at certain depths. These clay pockets are rich in organic matter, which may be the driving force for redox potential change and thus, may have driven the mobilisation of arsenic in groundwater. The clay pockets rich in organic matter presumably represent the major reservoir where arsenic is sitting and getting released due to redox mechanism. They are sampled at present. A piezometric depression cone characterized by a radial groundwater flow is located underneath the highly populated Lalpur area. The arsenic plume appears to migrate from the Hooghly river towards the cone of depression following the water flowpath, and this shall be verified in forthcoming field campaigns. As (III) constitutes 42 % of the total As concentration. It is several times more toxic than As (V). The As (III) / As (V) and S (-II) / S (VI) ratios are not at equilibrium with the Eh measured in groundwater. The groundwater is at equilibrium with Ba(II) and Fe(II) arsenate minerals, barite and siderite. The reactive transport modeling of the data is explored.
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    ABSTRACT: The Banded Hematite Jasper Formation within the Iron Ore Supergroup of the Singhbhum Craton in eastern India comprises fine alternating layers of jasper and specularite. It was deposited at ∼3000 Ma and deformed by a mobile episode at ∼2700 Ma. Hematite pigment (<1 μm) mixed with cryptocrystalline silica and specularite (> 10 μm) is chiefly responsible for red to brown rhythmic bands in the hematite jasper facies although thermomagnetic study also shows that minor amounts (1–2%) of magnetite are present. Palaeomagnetic study identifies a dual polarity remanence resident in hematite (, α95 = 12°) which predates deformation. Studies of the fabric of magnetic susceptibility and rock magnetic results suggest a diagenetic origin for this magnetisation with the hematite formed from oxidation of primary magnetite. The palaeopole (32°E, 24°N, ) records the earliest post-metamorphic magnetisation event in the Orissa Craton. A minimum apparent polar wander motion of the Orissa-Singhbhum craton of through 80° is identified during Late Archaean times (2900-2600 Ma).
    Precambrian Research 12/1996; 80:193-204. DOI:10.1016/S0301-9268(96)00012-5 · 6.02 Impact Factor
  • Graham J. Sherwood, S. Basu Mallik
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    ABSTRACT: A new palaeomagnetic study of mid Cretaceous lavas from 23 localities in the northern part of the Rajmahal Hills gives a mean virtual geomagnetic pole at 10.4°N, 296.6°E, confirming the results of earlier workers. Stepwise thermal and alternating field demagnetisation indicates that 21 out of 23 sites are normally magnetised, whereas two sites in the northwest of the area have recorded two different transitional directions. We have measured the strong-field thermomagnetic behaviour, DC and AC hysteresis parameters, and the variation at low temperature of low-field susceptibility of these and other samples from the Rajmahal Volcanics. These rock magnetic studies reveal that the basaltic lavas contain titanomagnetites which have hardly been oxidised at high temperature, but have undergone low temperature oxidation. The reddened lavas of Gandeswari Hill, on the other hand, show evidence of extensive high temperature deuteric oxidation of titanomagnetite.
    Journal of Asian Earth Sciences 02/1996; 13(2):123-131. DOI:10.1016/0743-9547(96)00013-X · 2.38 Impact Factor
  • S. Basu Mallik, Graham J. Sherwood, Assis K. Das
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    ABSTRACT: The Precambrian Banded Haematite Jasper rocks of Orissa show red and dark coloured rhythmic bands. The former are made up of cryptocrystalline silica and haematite pigment (<1 μm) and the latter of chiefly specularite (>10 μm). X-ray diffraction studies also seem to indicate that haematite is the only iron mineral present. However, rock magnetic studies suggest a more complex magnetic mineralogy. Variation of low field susceptibility from liquid nitrogen temperature to room temperature, strong field thermomagnetic behaviour from room temperature to 750°C, and hysteresis measurements show that some samples contain a small amount of magnetite or maghemite in addition to haematite. In some other samples magnetite may be produced on heating to temperatures between 470 and 700°C.
    01/1993; 45(2):155-165. DOI:10.5636/jgg.45.155
  • Graham Sherwood, John Shaw, Gidi Baer, S. Basu Mallik
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    ABSTRACT: We present the detailed results of our palaeointensity experiments on mid-Cretaceous basaltic lavas from the Rajmahal Traps in northeastern India and several formations in Israel. The aim of this study was to provide the first estimates of the geomagnetic field strength during the long period of normal polarity, the Cretaceous Quiet Zone. Using rock magnetic techniques-strong-field thermomagnetic behaviour, low-field low temperature susceptibility variation, and hysteresis properties, supported by optical and electron microscopy we have determined the magnetic mineralogy of the 48 sample sites. Deuteric oxidation is largely absent in both Israeli and Indian lavas, resulting in low Curie temperatures. Some degree of low temperature oxidation is always found in the Indian lavas, but is not common in the Israeli rocks. Stepwise thermal and alternating field demagnetisation show that many Israeli rocks have strong very soft overprints which may be lightning strikes. Although Cretaceous field directions are recorded in both Israeli and Indian lavas, and indicate that most of the lavas erupted during a period of normal polarity, the quality of the palaeomagnetic data is much higher in the Indian lavas with lower within site scatter. For each site, two samples were measured using the modified Thellier palaeointensity technique, and two using the Shaw technique with Rolph-Shaw correction. The magnetic mineralogy of the rocks are not conducive to obtaining good quality palaeointensity data. The within site scatter was often very high, particularly in the case of the Israeli lavas, where the Thellier technique often failed because secondary components could not be removed and the Shaw method failed because the rocks demagnetised completely at low alternating fields. This has led to one or two of the palaeointensity results being rejected from most sites, and a few Israeli sites being rejected altogether. The mean virtual dipole moment (VDM) from the Israeli lavas is 4.7 ± 2.2 (1 SD) × 1022 Am2 (from 20 out of 25 sites), and for the Rajmahal Traps 5.5 ± 1.9 × 1022 Am2 (from 23 out of 23 sites). Both mean VDMs are lower than our previously published preliminary estimates based only on Thellier data. From radiometric ages it would appear that the igneous activity in the Ramon and the Rajmahal areas is almost contemporaneous; hence the mean VDMs from these two formations should give a similar estimate of the mean dipole moment of the Earth at the beginning of the Cretaceous Quiet Zone. Combining the intensity data from these two areas, the estimated mean VDM for this time is 5.4 ± 1.9 × 1022 Am2 (n = 37). From this it appears that the Mesozoic dipole low had ended before the onset of the Cretaceous Quiet Zone.
    01/1993; 45(4):339-360. DOI:10.5636/jgg.45.339