Comparison of arsenic concentrations in simultaneously-collected groundwater and aquifer particles from Bangladesh,India, Vietnam,and Nepal

One of the reasons the processes resulting in As release to groundwater in southern Asia remain poorly understood is the high degree of spatial variability of physical and chemical properties in shallow aquifers. In an attempt to overcome this difficulty, a simple device that collects groundwater and sediment as a slurry from precisely the same interval was developed in Bangladesh. Recently published results from Bangladesh and India relying on the needle-sampler are augmented here with new data from 37 intervals of grey aquifer material of likely Holocene age in Vietnam and Nepal. A total of 145 samples of filtered groundwater ranging in depth from 3 to 36 m that were analyzed for As (1–1000 μg/L), Fe (0.01–40 mg/L), Mn (0.2–4 mg/L) and S (0.04–14 mg/L) are compared. The P-extractable (0.01–36 mg/kg) and HCl-extractable As (0.04–36 mg/kg) content of the particulate phase was determined in the same suite of samples, in addition to Fe(II)/Fe ratios (0.2–1.0) in the acid-leachable fraction of the particulate phase. Needle-sampler data from Bangladesh indicated a relationship between dissolved As in groundwater and P-extractable As in the particulate phase that was interpreted as an indication of adsorptive equilibrium, under sufficiently reducing conditions, across 3 orders of magnitude in concentrations according to a distribution coefficient of 4 mL/g. The more recent observations from India, Vietnam and Nepal show groundwater As concentrations that are often an order of magnitude lower at a given level of P-extractable As compared to Bangladesh, even if only the subset of particularly reducing intervals characterized by leachable Fe(II)/Fe >0.5 and dissolved Fe >0.2 mg/L are considered. Without attempting to explain why As appears to be particularly mobile in reducing aquifers of Bangladesh compared to the other regions, the consequences of increasing the distribution coefficient for As between the particulate and dissolved phase to 40 mL/g for the flushing of shallow aquifers of their initial As content are explored.     

Effect of metal content on chlorophyll fluorescence and chlorophyll degradation in lichen Pyxine cocoes (Sw.) Nyl.: a case study from Uttar Pradesh,India

The major aim of the present study is to identify the relationship of physiological parameters of the photosynthetic system with the elemental content of the naturally growing lichen Pyxine cocoes. The epiphytic foliose lichen P. cocoes was used as biomonitoring indicator and effect of atmospheric pollutants on physiological integrity was examined. Potential quantum yield of Photosystem II (fluorescence ratio Fv/Fm), chlorophyll degradation ratio and quantitative estimation of Al, As, Cd, Cr, Cu, Pb, Fe and Zn contained in the lichen thallus were ascertained. Statistical analysis revealed significantly positive correlations between Fv/Fm and element contents (Al and Cr). The chlorophyll degradation as well as alteration in the pigment content was found to be the most sensitive parameters to assess the vitality of lichen thallus against polluted environment. The species accumulated higher amounts of elements (Al, As, Cu, Fe and Zn) in the polluted sites as compared to the non polluted sites. It was also evident from this study that vehicular emission played a significant role in the release of elements as pollutants in the surrounding environment. The effectiveness of this lichen could be further investigated by comparing this species with other biomonitors.     

Radon emanation of heterogeneous basin deposits in Kathmandu Valley,Nepal

Effective radium-226 concentration (EC_Ra) has been measured in soil samples from seven horizontal and vertical profiles of terrace scarps in the northern part of Kathmandu Valley, Nepal. The samples belong to the Thimi, Gokarna, and Tokha Formations, dated from 50 to 14 ky BP, and represent a diverse fluvio-deltaic sedimentary facies mainly consisting of gravelly to coarse sands, black, orange and brown clays. EC_Ra was measured in the laboratory by radon-222 emanation. The samples (n = 177) are placed in air-tight glass containers, from which, after an accumulation time varying from 3 to 18 days, the concentration of radon-222, radioactive decay product of radium-226 and radioactive gas with a half-life of 3.8 days, is measured using scintillation flasks. The EC_Ra values from the seven different profiles of the terrace deposits vary from 0.4 to 43 Bq kg^?1, with profile averages ranging from 12 ± 1 to 27 ± 2 Bq kg^?1. The values have a remarkable consistency along a particular horizon of sediment layers, clearly demonstrating that these values can be used for long distance correlations of the sediment horizons. Widely separated sediment profiles, representing similar stratigraphic positions, exhibit consistent EC_Ra values in corresponding stratigraphic sediment layers. EC_Ra measurements therefore appear particularly useful for lithologic and stratigraphic discriminations. For comparison, EC_Ra values of soils from different localities having various sources of origin were also obtained: 9.2 ± 0.4 Bq kg^?1 in soils of Syabru–Bensi (Central Nepal), 23 ± 1 Bq kg^?1 in red residual soils of the Bhattar-Trisuli Bazar terrace (North of Kathmandu), 17.1 ± 0.3 Bq kg^?1 in red residual soils of terrace of Kalikasthan (North of Trisuli Bazar) and 10 ± 1 Bq kg^?1 in red residual soils of a site near Nagarkot (East of Kathmandu). The knowledge of EC_Ra values for these various soils is important for modelling radon exhalation at the ground surface, in particular in the vicinity of active faults. Importantly, the study also reveals that, above numerous sediments of Kathmandu Valley, radon concentration in dwellings can potentially exceed the level of 300 Bq m^?3 for residential areas; a fact that should be seriously taken into account by the governmental and non-governmental agencies as well as building authorities.     

Structural geology of Kusma-Sirkang section of the Kali Gandaki valley and its bearing on the tectonic framework of Nepal Himalaya

The rocks of the Kali Gandaki valley along the Kusma Sirkang section of Central West Nepal fall into two tectonic units having a marked difference in the grade of metamorphism. The units are demarcated by the NW-SE extending Phalebas Thrust which has been considered equivalent to the Chail Thrust of the Kumaon Himalaya by earlier workers. The Kusma Reverse Fault to the north parallels the Phalebas Thrust, both being related to Late Orogenic movements.The fold pattern shows at least four episodes, and it is believed that two of them existed prior to the main Himalayan orogeny of Tertiary time.     

Impact assessment of anthropogenic activities on air quality, using lichen Remototrachyna awasthii as biomonitor

The study was carried out with an aim to assess the heavy metal (HM) and polycyclic aromatic hydrocarbons (PAHs) in the air of a biodiversity as well as tourist-rich area of Western Ghats by applying a most frequent growing lichen Remototrachyna awasthii (Hale and Patw.) Divakar and A. Crespo, as biomonitor. Thalli of R. awasthii were collected from eight sites of Mahabaleshwar area located in Western Ghats. Samples were prepared for HM and PAHs quantification by ICP-MS and HPLC, respectively. Total metal concentration (HM) ranged from 644 to 2,277.5 μg g^?1 while PAHs concentration between 0.193 and 54.78 μg g^?1. HM and PAHs concentrations were the highest at Bus Stand while control site (Lingmala Fall) exhibited the lowest concentration of HM as well as PAHs followed by samples from Wilson point (both these sites are having trekking route). It was also evident from this study that vehicular emission played a significant role in the release of HM and PAHs as pollutants in the environment. The effectiveness of R. awasthii as biomonitor could be further investigated by comparing this species with other biomonitors.     

Kali Gandaki gravel deposits of central West Nepal — their neotectonic significance

The terraced gravel deposits of the Baglung-Behadi region in the Kali Gandaki valley, central West Nepal, reveal geomorphic features related to neotectonism. The accumulation of thick fluvioglacial gravel deposits in lake-like basins along the then existing river course took place due to the uplift of the southern Mahabharat Range and the relative subsidence of the Midland. The deposits consist of unsorted fragments of variable size, showing considerable uniformity laterally over large areas from north to south, and with abundant angular to sub-rounded boulders of Dhaulagiri limestone and gneisses of the Main Central Crystallines. Terrace flats arranged in three successive levels on either side of Kali Gandaki show that the region has undergone at least three periods of uplift.     

GEOLOGY OF THE TAPLEJUNG WINDOW AND FRONTAL BELT, FAR EASTERN NEPAL HIMALAYA

GEOLOGY OF THE TAPLEJUNG WINDOW AND FRONTAL BELT, FAR EASTERN NEPAL HIMALAYA1　PecherA .Deformationandmetamorphismeassociesaunezonedecisaillement :Exampledugrandchevauchementcen tralHimalayan (MCT) [M ].Thesed’Etat,UnivGrenoble ,France ,1978.35 4. 2　RaiSM .LesnappesdeKathmandudtduGosainkund ,HimalayaduNepalcentral[M ].Thesededoctoral,Univ .Grenoble ,France ,1998.2 44 . 3　SchellingD ,AritaK .Thrusttectonics ,crustalshortening ,andthestructureofthe…     

Role of latitudinal shift and climate change in evolution of red and yellow palaeosols of the Himalayas: Implications for early Oligocene seasonality and Mid-Miocene enhanced precipitation

Cenozoic atmospheric circulation, climatic changes, sedimentation and weathering over the Indian sub-continent were mainly influenced by the northward drift of the Indian Plate, the shrinking Paratethys, India-Asia collision and the rise of the Himalayas. This study is aimed at exploring the fluvial sedimentary record of the north-west part of the Himalayan Foreland Basin to interpret weathering and pedogenesis during early Oligocene to Mid-Miocene time. Palaeopedological investigation of a 3.1 km thick succession from Kangra sub-basin of the Himalayan Foreland Basin shows that the lower 2 km part of the succession is characterized by the red (10R hue) and the upper 1.1 km part of the succession by the yellow (2.5Y hue) palaeosols with varying intensity of weathering and pedogenesis. The association of sedimentary rocks and pedogenic expression in palaeosols indicate four (Type-A to Type-D) pedofacies in the entire Oligocene–Miocene succession. The pedofacies are defined by a decrease in the intensity of palaeopedogenic development from strongly-developed palaeopedofeatures in Type-A, moderately-developed palaeopedofeatures in Type-B, weakly-developed palaeopedofeatures in Type-C and to the only incipient stage of palaeopedogenesis in Type-D pedofacies. The palaeolatitudinal shift during the convergence of the Indian Plate played a major role in weathering and palaeopedogenesis with the inception of seasonality during the early Oligocene, which is demonstrated by the formation of the red palaeosols with pedogenic CaCO₃ and vertic features in tropical conditions. The transition to yellow palaeosols at about 20 Ma is marked by increased humidity, rapid aggradation, pronounced uplift and enhanced erosion of the hinterland. These yellow palaeosols are characterized by the abundance of weakly-developed Bw and Bss horizons, pure clay pedofeatures and absence of any pedogenic CaCO₃ during short pedogenic intervals in subtropical conditions.     

A comparison of metallic contents in lichen Pyxine subcinerea, its substratum and soil

Chromium, copper, cadmium, lead, nickel, iron and zinc contents of a lichen species (Pyxine subcinerea Stirton) and mango bark collected from 12 sites in Haridwar city (Uttarakhand) were compared with soil, sampled from beneath the tree from which lichens were collected. The metal contents in lichen, bark and soil ranged from 1,573 to 18,793, 256 to 590 and 684 to 801 μg g^?1, respectively. This clearly indicates that lichens accumulated higher amounts of metal compared to bark or soil. Statistical analysis revealed that metal concentration in lichens did not show significant linear correlation with the bark or soil. Pearsons correlation coefficients revealed negative correlation of Pb (r = ?0.2245) and Ni (r = ?0.0480) content between lichen and soil, which indicate direct atmospheric input of metals from ambient environment. Quantification and comparison of elemental concentration in lichens, its substratum and soil can provide valuable information about air quality in the collection area.