Geochemical characterization of arsenic-affected alluvial aquifers of the Bengal Delta (West Bengal and Bangladesh) and Chianan Plains (SW Taiwan): Implications for human health

Major ion and trace element analyses were performed on groundwater samples collected from the Bengal Delta (Chakdaha municipality, West Bengal and Manikgonj town, Bangladesh) and Chianan Plains (SW Taiwan) to compare geochemical characteristics. Results showed that concentrations of Na, K, Mg, Cl and SO₄ were generally higher in Chianan Plain (CNP) groundwaters, while high Ca was observed in Bengal Delta Plain (BDP) groundwater. Measured As concentrations in groundwaters of BDP and CNP showed large variations, with mean As concentrations of 221 μg/L (range: 1.1-476 μg/L) in Chakdaha, 60 μg/L (range: 0.30-202 μg/L) in Manikgonj, and 208 μg/L (range: 1.3-575 μg/L) in CNP groundwater. The Fe-reduction mechanism was found to be the dominant geochemical process in releasing As from sediment to groundwater in Chakdaha, West Bengal, however the Mn-reduction process was dominant in groundwaters of Manikgonj, Bangladesh. In Chianan Plain groundwater, a combination of geochemical processes (e.g., bacterial Fe-reduction, mineral precipitation and dissolution reactions) controlled release of As. Fluorescence spectral patterns of the groundwater showed low relative fluorescence intensity (RFI) of dissolved humic substances in BDP groundwater (mean: 63 and 72 QSU, Chakdaha and Manikgonj, respectively), while high RFI was observed in CNP groundwater (mean: 393 QSU). The FT-IR spectra of the extracted humic acid fractions from sediments of Chianan Plain showed a stronger aliphatic band at 2850-3000 cm⁻¹ and a higher resolved fingerprint area (from 1700 to 900 cm⁻¹) compared with BDP sediments. The geochemical differences between the study areas may play a crucial role in the clinical manifestation of Blackfoot disease observed only in Chianan Plain, SW Taiwan.     

Determination of runoff and sediment yield from a small watershed in sub‐humid subtropics using the HSPF model

The Hydrologic Simulation Programme‐Fortran (HSPF), a hydrologic and water quality computer model, was employed for simulating runoff and sediment yield during the monsoon months (June–October) from a small watershed situated in a sub‐humid subtropical region of India. The model was calibrated using measured runoff and sediment yield data for the monsoon months of 1996 and was validated for the monsoon months of 2000 and 2001. During the calibration period, daily‐calibrated runoff had a Nash‐Sutcliffe efficiency (E_NS) value of 0·68 and during the validation period it ranged from 0·44 to 0·67. For daily sediment yield E_NS was 0·71 for the calibration period and it ranged from 0·68 to 0·90 for the validation period. Sensitivity analysis was performed to assess the impact of important watershed characteristics. The model parameters obtained in this study could serve as reference values for model application in similar climatic regions, with practical implications in watershed planning and management and designing best management practices. Copyright © 2007 John Wiley & Sons, Ltd.     

Groundwater arsenic contamination and its health effects in India

During a 28-year field survey in India (1988–2016), groundwater arsenic contamination and its health effects were registered in the states of West Bengal, Jharkhand, Bihar and Uttar Pradesh in the Ganga River flood plain, and the states of Assam and Manipur in the flood plain of Brahamaputra and Imphal rivers. Groundwater of Rajnandgaon village in Chhattisgarh state, which is not in a flood plain, is also arsenic contaminated. More than 170,000 tubewell water samples from the affected states were analyzed and half of the samples had arsenic >10 μg/L (maximum concentration 3,700 μg/L). Chronic exposure to arsenic through drinking water causes various health problems, like dermal, neurological, reproductive and pregnancy effects, cardiovascular effects, diabetes mellitus, diseases of the respiratory and gastrointestinal systems, and cancers, typically involving the skin, lungs, liver, bladder, etc. About 4.5% of the 8,000 children from arsenic-affected villages of affected states were registered with mild to moderate arsenical skin lesions. In the preliminary survey, more than 10,000 patients were registered with different types of arsenic-related signs and symptoms, out of more than 100,000 people screened from affected states. Elevated levels of arsenic were also found in biological samples (urine, hair, nails) of the people living in affected states. The study reveals that the population who had severe arsenical skin lesions may suffer from multiple Bowens/cancers in the long term. Some unusual symptoms, such as burning sensation, skin itching and watering of eyes in the presence of sun light, were also noticed in arsenicosis patients.     

Quantitative measurement of arid fluvial processes: Results from an upland catchment in Thar Desert

A quantitative study on fluvial processes was carried out in an upland stream catchment (9.3 ha) near Agolai in the NE of Jodhpur district in the Thar Desert in Rajasthan. The catchment of the studied second order ephemeral channel (1.0–1.4 km long and 1.0–1.5 m deep) has developed on a hill — rocky/gravelly pediment — colluvial plain sequence on rhyolite. Initial results of measurements of channel parameters during two significant runoff generating events of 42 mm and 52 mm in 2007 showed peak discharges of 20 m³s⁻¹ (upstream) and 13 m³s⁻¹ (downstream) that moved sediments (bedload) to distances of 43 m − 141 m in the upstream reach, 6–28 m in the middle reach and 63–95 m in the lower reach. The long profile and cross profile measurements showed a balance between load and discharge through a sequence of alternate deposition and erosion throughout the channel. Hypsometry curves revealed maximum erosion (7.7 cm) in the upper reach and aggradation (2.90 cm) in the lower reach. Cross profile measurements showed bank cuts (6 cm) and vertical incisions (1–2 cm) on the rocky-gravelly V shaped valley in the upper reach, incision (4–30 cm) and localized higher deposition (10–12 cm) in the narrow (<1m) and deep (>1m) U shaped valleys in middle reach and mainly deposition (13 cm) on the wide ( 1–4 m) and shallow channels (0.1 to 0.2 m) in the lower reach.     

Petrogenesis of granitoid rocks at the northern margin of the Eastern Ghats Mobile Belt and evidence of syn-collisional magmatism

The northern margin of the Eastern Ghats Mobile belt against the Singhbhum craton exposes granitic rocks with enclaves from both the high-grade and low-grade belts. A shear cleavage developed in the boundary region is also observed in these granitoids. Field features and petrography indicate syn-tectonic emplacement of these granitoids. Petrology-mineralogy and geochemistry indicate that some of the granitoids are derived from the high-grade protoliths by dehydration melting. Others could have been derived from low-grade protoliths. Moreover, microstructural signatures in these granitoids attest to their syn-collisional emplacement.     

Plant pathogen Protocolletotrichum from a Deccan intertrappean bed (Maastrichtian), India

A fossil fungus related to Colletotrichum Corda, which causes leaf spot and red rot in plants, was recovered from an intertrappean bed intersected by a well at Mohgaon-Kalan village, Chhindwara District, Madhya Pradesh. The intertrappean bed is sandwiched between the two basaltic flows and is dated as Maastrichtian on the basis of plant and animal fossils. Radiometric dating of the volcanic rocks yielded ages of 67.8–61.6 Ma. The specimens are preserved on a leaf cuticle and are named Protocolletotrichum deccanensis gen. et sp. nov. They are strongly constructed, 1–2 septate, dark brown setae, each with a slightly swollen base and pointed tip.     

Hydrogeomorphological mapping in ground water exploration using remotely sensed data — a case study in keonjhar district, orissa

Identification of fractures/lineaments and hydrogeomorphic units is prerequisite for undertaking ground water exploration and development in any terrain. Use of satellite remote sensing techniques coupled with aerial photo-interpretation greatly aid in planning ground water exploration, and pin pointing well sites In this study, airborne and space borne data was used for qualitative evaluation of ground water resources and a critical appraisal of such study in combination with hydrogeological and hydrogeophysical techniques for ground water exploration and development in Keonjhar district of Orissa. The study area has been divided into various geomorphic units based on visual interpretation of Landsat (TM) false colour composite on. 1:2,50,000 scale and the ground water potential of each of the units is qualitatively assessed. Digital image processing techniques such as principal component analysis and brightness index were used for generating classified outputs. The features like valley fills, pediments ete appeared clearly on the classified image. Directional filtering brought out minor fractures/lineaments crisply. The study has revealed the significance of different hydrogeomorptuc units and lineaments in Controlling ground water potential of the area. The findings were corroborated by resalts of drilling and resistivity soundings.     

Modelling of non-point source pollution in a watershed using remote sensing and gis

Assessment of the environmental impact of Non Point Source (NPS) pollutants on a global, regional and localized scale is the key component for achieving sustainability of agriculture as well as preserving the environment. The knowledge and information required to address the problem of assessing the impact of NPS pollutants like Nitrogen (N), Phosphorus (P), etc., on the environment crosses several sub-disciplines like remote sensing, Geographical Information System (GIS), hydrology and soil science. The remote sensing data, by virtue of its potential like synopticity, multi-spectral and multi-temporal capability, computer compatibility, besides providing almost real time information, has enhanced the scope of automation of mapping dynamic elements, such as land use/land cover, degradation profile and computing the priority categorisation of sub-watersheds. The present study demonstrates the application of remote sensing, GIS and distributed parameter model Agricultural Non-Point Source Pollution Model (AGNPS) in the assessment of hazardous non-point source pollution in a watershed. The ARC-INFO GIS and remote sensing provided the input data to support modelling, while the AGNPS model predicted runoff, sediment and pollutant (N and P) transport within a watershed. The integrated system is used to evaluate the sediment pollution in about 2700 ha Karso watershed located in Hazaribagh area of Jharkhand State, India. The predicted values of runoff and sediment yield copared reasonably well with the measured values. It is important to emphasize that this study is not intended to characterise, in an exhaustive manner. Instead, the goal is to illustrate the implications and potential advantages of GIS and remote sensing based Hydrology and Water quality (H/WQ) modelling framework.