Integration of magnetism and heavy metal chemistry of soils to quantify the environmental pollution in Kathmandu, Nepal

Abstract Soil profiles of the Kathmandu urban area exhibit significant variations in magnetic susceptibility (χ) and saturation isothermal remanence (SIRM), which can be used to discriminate environmental pollution. Magnetic susceptibility can be used to delineate soil intervals by depth into normal (< 10^?7 m³/kg), moderately enhanced (10^?7–< 10^?6 m³/kg) and highly enhanced (≥ 10^?6 m³/kg). Soils far from roads and industrial sites commonly fall into the ‘normal’ category. Close to a road corridor, soils at depths of several centimeters have the highest χ, which remains high within the upper 20 cm interval, and decreases with depth through ‘moderately magnetic’ to ‘normal’ at approximately 30–40 cm. Soils in the upper parts of profiles in urban recreational parks have moderate χ. Soil SIRM has three components of distinct median acquisition fields (B_1/2): soft (30–50 mT, magnetite‐like phase), intermediate (120–180 mT, probably maghemite or soft coercivity hematite) and hard (550–600 mT, hematite). Close to the daylight surface, SIRM is dominated by a soft component, implying that urban pollution results in enrichment by a magnetite‐like phase. Atomic absorption spectrometry of soils from several profiles for heavy metals reveals remarkable variability (ratio of maximum to minimum contents) of Cu (16.3), Zn (14.8) and Pb (9.3). At Rani Pokhari, several metals are well correlated with χ, as shown by a linear relationship between the logarithmic values. At Ratna Park, however, both χ and SIRM show significant positive correlation with Zn, Pb and Cu, but poor and even negative correlation with Fe (Mn), Cr, Ni and Co. Such differences result from a variety of geogenic, pedogenic, biogenic and man‐made factors, which vary in time and space. Nevertheless, for soil profiles affected by pollution (basically traffic‐related), χ exhibits a significant linear relationship with a pollution index based on the contents of some urban elements (Cu, Pb, Zn), and therefore it serves as an effective parameter for quantifying the urban pollution.     

Combining geomatics and conventional methods for monitoring forest conditions under different governance arrangements

Introduction Assessment and systematic resource condition monitoring are essential components of long-term planning and management of forest resources. These requirements can be fulfilled using different methods and techniques. Traditionally, when the primary objective of forest management was tim- ber production, sample-based forest inventories were the sole method of determining forest condi- tions. Aerial photographs were frequently used for forest cover mapping during the third quarter of …     

A new kinematic evolutionary model for the growth of a duplex — an example from the Rangit duplex, Sikkim Himalaya, India

The Lesser Himalayan duplex (LHD) is a prominent structure through much of the Lesser Himalayan fold–thrust belt. In the Darjeeling - Sikkim Himalaya a component of the LHD is exposed in the Rangit window as the Rangit duplex (RD). The RD consists of ten horses of the upper Lesser Himalayan Sequence (Gondwana, Buxa, Upper Daling). The duplex varies from hinterland-dipping in the north, through an antiformal stack in the middle to foreland-dipping in the south. The Ramgarh thrust (RT) is the roof thrust and, based on a balanced cross-section, the Main Himalayan Sole thrust is the floor thrust at a depth of ~ 10 km and with a dip of ~ 3.5° N.Retrodeformation suggests that the RD initiated as a foreland-dipping duplex with the Early Ramgarh thrust as the roof thrust and the RT as the floor thrust. The RT became the roof thrust during continued duplexing by a combination of footwall imbrication and concurrent RT reactivation. This kinematic history best explains the large translation of the overlying MCT sheets. The restoration suggests that RD shortening is ~ 125 km, and the original Gondwana basin extended ~ 142 km northward of its present northernmost exposures within the window.     

Implications of urban expansion on land use and land cover: towards sustainable development of Mega Manila,Philippines

GeoJournal - Planning of land use and infrastructure in advance for a population that is projected to grow rapidly is highly important for its sustainable development. A correlative approach of...     

Seismicity and reservoir induced crustal motion study around the Tehri Dam, India

The Tehri Dam is located in a seismotectonically active region in the Indian Himalayan belt. This 260.5 m high dam has a live water storage of 2615 × 10⁶ m³ and is capable of generating crustal deformation corresponding to water fluctuation. Filling of the reservoir started in October 2005. Seismic data around the dam between 2000 and 2010 shows that seismicity is corresponding to drawdown levels of the reservoir rather than to higher water levels. GPS data at twelve local benchmarks were collected from 2006 to 2008 during filling and drawdown reservoir levels. The velocity vectors show ground motion to be between ～0.69–1.50 mm in the different filling-drawdown cycles with reference to the permanent station at Ghuttu. The motion appears to be inwards into the reservoir when the reservoir is filled and outwards when the reservoir is drained. This ground motion corresponds to elastic deformation and rebound due to effect of the oscillating water levels.     

Study of mechanical properties of Vindhayan shaly rocks at elevated temperature

Shale is an important rock due to its suitability for different engineering and scientific applications. Elevated temperature may cause major deformation or damage in shale rock and it may be of irreversible in nature. Such damage have adverse effect on the physicomechnical properties of shale rock. The uniaxial compressive strength and tensile strength of two shales (upper Vindhyan basin, India) have been estimated at elevated temperature using point load strength index method. The rock samples have been analyzed at various temperatures starting from room temperature to 900 °C. The effect of elevated temperature on the physicomechanical properties and their influence on the uniaxial compressive strength has been studied in detail. Damage induced, in both shale have been estimated using compressional wave velocity. The analysis of the experimental result shows that the uniaxial compressive strength decreases from 63.45 to 18.45 MPa and 60.94 to 22.22 MPa, for Jhiri and Ganurgarh shale respectively. Tensile strength of shales have been also estimated. The value of tensile strength decreases from 3.65 to 1.05 MPa and 3.46 to 1.26 MPa respectively for Jhiri and Ganurgarh shale. Multivariate regression analysis has been carried out to obtain the correlation between physicomechanical properties and uniaxial compressive strength of Jhiri and Ganurgarh shale.     

An Analytical Solution for Predicting Transient Seepage into Partially Penetrating Ditch Drains Receiving Water from a Ponded Field

A transient analytical model is worked out for predicting seepage from a ponded field of infinite extent to a network of equally spaced ditch drains in a homogeneous and anisotropic soil underlain by an impervious barrier at a finite distance from the surface of the soil. The solution can account for finite width and finite level of water in the ditches, finite penetration of the drains in the soil, and also a variable ponding field at the surface of the soil. The study highlights the fact that the transient state duration of a partially penetrating ponded drainage scenario may be considerable should the drains be dug in a lowly conductive soil with a high storage coefficient, particularly if the underlying impervious layer lies at a large distance from the bottom of the ditches and the separation between the adjacent ditches is also large at the same time.     

Mapping of environs of Dharavi slums of Greater Bombay for site suitability using enhanced Landsat thematic mapper (TM) imagery

Slums are universal and a ubiquitous part of the urban landscape. Dharavi, the biggest slum in the whole of Greater Bombay, encompasses 4.0 sq.km. of reclaimed land with 3.50 lakh inhabitants and 75,000 hutments. Majority of the slums of Indian cities, being structurally small with high density of dwellings and uniform building material, seldom give subtle ’spectral signature’ on the satellite imagery. Here, an attempt has been made to map by visual techniques the land use of Dharavi and environs of 20 sq.km area, using optically enhanced Landsat (TM) FCC of January, 1986, on 1:25,000 sale, The study has clearly brought out the land use details, the areas undergoing reclamation, and those susceptible to hazards like floods and marine erosion. A few alternate sites, based on geomorphic attributes are suggested for resettlement of Dharavislum and their areas are also quantified. The results of the present work is a part of the project study completed for a larger area covering 150sq. kms.     

Geochemistry of basalts from the Dumisseau Formation, southern Haiti: implications for the origin of the Caribbean Sea crust

Basalt and diabase from the Cretaceous Dumisseau Formation, southern Haiti have Mg-numbers of 43–63, TiO₂ contents of 1.6–3.9% and La abundances of 3.6–15.3 ppm.La/Ta ratios average 10, and indicate that the basalts are oceanic in character, distinct from the arc associations forming the northern part of Haiti. Oldest lavas have low TiO₂ (1.6%) and are LREE-depleted, similar to N-MORBs, whereas overlying lavas have higher TiO₂ (2–3.9%) and are LREE-enriched, similar to E-MORBs or hotspot basalts.⁸⁷Sr⁸⁶Sr ratios vary from 0.70280 to 0.70316,¹⁴³Nd¹⁴⁴Nd from 0.512929 to 0.513121, and²⁰⁶Pb²⁰⁴Pb from 19.00 to 19.27. LREE-depleted lavas have high¹⁴³Nd¹⁴⁴Nd (0.51309–0.51310) typical of MORBs, whereas¹⁴³Nd¹⁴⁴Nd in the LREE-enriched lavas varies widely (0.512929–0.513121).Chemical features of the Dumisseau basalts are equivalent to those of Caribbean seafloor basalts recovered on DSDP Leg 15, and support the contention that the Dumisseau is an uplifted section of Caribbean Sea crust. Oldest lavas are analogous to MORB-like basalts cored at Leg 15 Sites 146, 150, 152 and 153, and the overlying lavas are analogous to incompatible-element-enriched basalts cored at Site 151 on the Beata Ridge. Isotopic compositions of the Dumisseau basalts overlap with those of the eastern Pacific Galapagos and Easter Island hotspots. However, the presence of N-MORB basalts in the lower part of the Dumisseau and at the majority of Leg 15 Sites indicates that the anomalously thick Caribbean crust probably did not originate as a hotspot-related basaltic plateau, but may have been generated by on-ridge or near-ridge hotspot magmatism.