Arsenic contamination of groundwater:A global synopsis with focus on the Indian Peninsula

More than 2.5 billion people on the globe rely on groundwater for drinking and providing high-quality drinking water has become one of the major challenges of human society.Although groundwater is considered as safe,high concentrations of heavy metals like arsenic(As)can pose potential human health concerns and hazards.In this paper,we present an overview of the current scenario of arsenic contamination of groundwater in various countries across the globe with an emphasis on the Indian Peninsula.With several newly affected regions reported during the last decade,a significant increase has been observed in the global scenario of arsenic contamination.It is estimated that nearly 108 countries are affected by arsenic contamination in groundwater with concentration beyond maximum permissible limit of 10 ppb recommended by the World Health Organization.The highest among these are from Asia(32)and Europe(31),followed by regions like Africa(20),North America(11),South America(9)and Australia(4).More than 230 million people worldwide,which include 180 million from Asia,are at risk of arsenic poisoning.Southeast Asian countries,Bangladesh,India,Pakistan,China,Nepal,Vietnam,Burma,Thailand and Cambodia,are the most affected.In India,20 states and 4 Union Territories have so far been affected by arsenic contamination in groundwater.An attempt to evaluate the correlation between arsenic poisoning and aquifer type shows that the groundwater extracted from unconsolidated sedimentary aquifers,particularly those which are located within the younger orogenic belts of the world,are the worst affected.More than 90%of arsenic pollution is inferred to be geogenic.We infer that alluvial sediments are the major source for arsenic contamination in groundwater and we postulate a strong relation with plate tectonic processes,mountain building,erosion and sedimentation.Prolonged consumption of arsenic-contaminated groundwater results in severe health issues like skin,lung,kidney and bladder cancer;coronary heart disease;bronchiectasis;hyperkeratosis and arsenicosis.Since the major source of arsenic in groundwater is of geogenic origin,the extend of pollution is complexly linked with aquifer geometry and aquifer properties of a region.Therefore,remedial measures are to be designed based on the source mineral,climatological and hydrogeological scenario of the affected region.The corrective measures available include removing arsenic from groundwater using filters,exploring deeper or alternative aquifers,treatment of the aquifer itself,dilution method by artificial recharge to groundwater,conjunctive use,and installation of nano-filter,among other procedures.The vast majority of people affected by arsenic contamination in the Asian countries are the poor who live in rural areas and are not aware of the arsenic poisoning and treatment protocols.Therefore,creating awareness and providing proper medical care to these people remain as a great challenge.Very few policy actions have been taken at international level over the past decade to reduce arsenic contamination in drinking water,with the goal of preventing toxic impacts on human health.We recommend that that United Nations Environment Programme(UNEP)and WHO should take stock of the global arsenic poisoning situation and launch a global drive to create awareness among people/medical professionals/health workers/administrators on this global concern.

Seismicity of Global Tectonic Systems Obtained from the Harvard CMT Catalogue

Earthquake is the best information source for describing the present-day crustal tectonic zones and crustal stress field, containing comprehensive and abundant geodynamic connotations. Based on the distribution of global earthquakes and their kinematic and dynamic characteristics, the most active global-scale tectonics can be divided into three first-order tectonic systems: the Circum-Pacific deep subduction tectonic system, the mid-oceanic ridge tectonic system, and the continent-continent shallow underthrusting tectonic system using the Harvard CMT catalogue that provides various parameters of hypocenter. Furthermore, the differences of fault types, seismicity, and distribution of focal depths in different tectonic systems are discussed as well. The results show that different tectonic system possesses different environment and geodynamics.

Vortex Theory and Earth Dynamics

Morphological evidence in active tectonic areas originate from alternative mechanisms to those described consisting of subcircular shapes suggests that these geometries may by translational dynamics of complex faults. The mechanics behind endogenic forces, in particular convection currents, hasn＇t been completely explained. Differing in density from upward flows developing in atmosphere and in water, magma upwelling from the mantle can trigger endogenic vortexes in particular conditions and due to Coriolis Force. At their onset and ascent phase, vortexes apply lateral forces as result of rotation, open their way toward the surface and over time stabilize the channel. Opposite to a rising linear flow which compacts overlying materials impeding their surge, vortex flows unload the materials externally and compact them on the lateral surface of the channel, thus making it more regular and stable. Torsional movements on the surface associated to vulcanites, lateral ramps and subcircular elevations, can be observed. Other phenomena that may be consequence of vortex dynamics are the volcanic cones showing pseudo-rotations in the morphologies surrounding the crater. In this study we suggest a modeling for a vortex theory which may explain the Earth dynamics in terms of spiraling movement and magma upwelling stabilizing over time.

Identification of Five Stages of Dike Swarms in the Shanxi-Hebei-Inner Mongolia Border Area and Its Tectonic Implications

Dike swarms are generally ascribed to intrusion of mantle-source magma result from extension. Basic dike swarms around the Shanxi-Hebei-Inner Mogolia borders in the northern peripheral area of the North China Craton can be divided into five age groups according to isotopic dating: 1800-1700 Ma, 800-700 Ma, 230 Ma, 140-120 Ma, and 50-40 Ma. Geological, petrological and isotope geochemical features of the five groups is investigated in order to explore the variation of the mantle material composition in the concerned area with time. And the various extensional activities reflected by the five groups of dike swarms are compared with some important tectonic events within the North China Craton as well as around the world during the same period.

The fallacy of interpreting SSDS with different types of breccias as seismites amid the multifarious origins of earthquakes:Implications

At present, there are no criteria to distinguish soft-sediment deformation structures （SSDS） formed by earthquakes from SSDS formed by the other 20 triggering mechanisms （see a companion paper in Vol 5, No. 4 of this journal by Shanmugam, 2016）. Even if one betieves that earthquakes are the true triggering mechanism of SSDS in a given case, the story is stiff incomptete. This is because earthquakes （seismic shocks） are induced by a variety of causes： 1） glbaltectonics and associated faults （i.e., midocean ridges, trenches, and transform fautts）; 2） meteorite-impact events; 3） volcanic eruptions; 4） post-gtacialuplift; 5） tsunami impact; 6 cyclonic impact; 7） landslides （mass-transport deposits）; 8） tidal activity; 9） sea-tevet rise; 10） erosion; and 11） fluid pumping. These different causes are important for devetoping SSDS. Breccias are an important group of SSDS. Although there are many types of breccias classified on the basis of their origin, five types are discussed here （fault, volcanic, meteorite impact, sedimentary-depositionaL, sedimentary-collapse）. Atthough different breccia types may resemble each other, distinguishing one type （e.g., meteorite breccias） from the other types （e.g., fault, volcanic, and sedimentary breccias） has important imptications. 1） Meteorite breccias are characterized by shock features （e.g., planar deformation features in mineral grains, planar fractures, high-pressure polymorphs, shock melts, etc.）, whereas sedimentary- depositional breccias （e.g., debrites） do not. 2） Meteorite breccias imply a confined sediment distribution in the vicinity of craters, whereas sedimentary-depositional breccias imply an unconfined sediment distribution, variable sediment transport, and variable sediment provenance. 3） Meteorite, volcanic, and fault breccias are invariabty subjected to diagenesis and hydrothermat mineratization with attered reservoir quality, whereas sedimentary-depositional breccias exhibit primary （unaltered） reservoir quality. And finalty, 4） sedimentary-collapse breccias are associated with economic mineralization （e.g., uranium ore）, whereas sedimentary-depositional breccias are associated with petroleum reservoirs. Based on this important group of SSDS with breccias, the current practice of interpreting all SSDS as ＂seismites＂ is inappropriate. Ending this practice is necessary for enhancing conceptuat clarity and for advancing this research domain.