Assessment of Hurricane Ivan impact on chlorophyll-a in Pensacola Bay by MODIS 250 m remote sensing

The impact of Hurricane Ivan on water quality in Pensacola Bay was investigated by MODIS 250 m remote sensing of chlorophyll-a concentrations at different time slots before and after the hurricane event. Before the hurricane, the mean chlorophyll-a in the Bay was 5.3 μg/L. Heavy rainfall occurred during the hurricane landfall. The 48 h rainfall reached 40 cm and the peak storm surge reached 3 m on 9/16. After the rainstorm and during the storm surge on 9/17/2004, the mean chlorophyll-a concentration substantially increased to 14.7 μg/L. 26.3% water area was in the poor-water-quality condition (chl-a > 20 μg/L). This indicates that heavy nutrient loads from urban stormwater runoff and storm-surge inundation simulated chlorophyll bloom. After the end of the storm surge on 9/18/2004, the mean chlorophyll dropped to 2.0 μg/L, suggesting the effective flushing of polluted water from the bay to the Gulf of Mexico by the storm-surge. The good water quality condition lasted for almost several weeks after the storm surge. The peak river flow, arriving on the 4th day after the peak storm surge, did not alter the good water quality situation in the bay. This indicates that urban stormwater runoff rather than the river inflow is the major pollutant source for water quality in Pensacola Bay during the hurricane.     

Role of crustal heterogeneity beneath Andaman–Nicobar Islands and its implications for coastal hazard

The Andaman–Nicobar (A–N) Islands region has attracted many geo-scientists because of its unique location and complex geotectonic settings. The recent occurrence of tsunamis due to the megathrust tsunamigenic north Sumatra earthquake (Mw 9.3) with a series of aftershocks in the A–N region caused severe damage to the coastal regions of India and Indonesia. Several pieces of evidence suggest that the occurrence of earthquakes in the A–N region is related to its complex geodynamical processes. In this study, it has been inferred that deep-seated structural heterogeneities related to dehydration of the subducting Indian plate beneath the Island could have induced the process of brittle failure through crustal weakening to contribute immensely to the coastal hazard in the region. The present study based on 3-D P-wave tomography of the entire rupture zone of the A–N region using the aftershocks of the 2004 Sumatra–Andaman earthquake (Mw 9.3) clearly demonstrates the role of crustal heterogeneity in seismogenesis and in causing the strong shakings and tsunamis. The nature and extent of the imaged crustal heterogeneity beneath the A–N region may have facilitated the degree of damage and extent of coastal hazards in the region. The 3-D velocity heterogeneities reflect asperities that manifest what type of seismogenic layers exist beneath the region to dictate the size of earthquakes and thereby they help to assess the extent of earthquake vulnerability in the coastal regions. The inference of this study may be used as one of the potential inputs for assessment of seismic vulnerability to the region, which may be considered for evolving earthquake hazard mitigation model for the coastal areas of the Andaman–Nicobar Islands region.     

Imaging and visualizing the spectral signatures from Landsat TM and ‘τ’ value-based surface soil microzonation mapping at and around Agartala (India)

This work aims to assess the soil microzonation of Agartala city and its surrounding areas based on spectral geophysical signatures. Different spectral resolutions of Landsat TM have been used for assessing the Normalized Difference Vegetative Index, spatial thermal emission representation and plant water moisture representation. Normalized Difference Vegetative Index (NDVI) was measured from band 4 (near-infrared (NIR)) and band 3 (photosynthetically active radiation (PAR)). The Digital Number (DN) values of thermal infrared band (TIR) were used for measuring spatial variation of thermal representation in the city area. A very simple model was developed for measuring thermal emission representative index from NDVI and automated classified TIR band. Overlaid NDVI and classified TIR shows the spatial distribution of thermal emission representative values. Classified mid-wave infrared band (MWIR) was used for measuring the surface geotherm units (τ) which are related with different types of soil. On the basis of spatial distribution of τ value which is clearly visible in a thermal emission representative map overlaid by classified MWIR, the soil microzonation map of the study area was prepared. This soil microzonation map shows that Agartala and its surrounding areas are characterized by four types of soil which are related to different geomorphic and geological units. The soil of this area is classified as dry sandy soil and sandy clay soil of the highland areas and wet sandy alluvium and clayey alluvium of the flood plain area.     

A Review of “India's New Economic Policy: A Critical Analysis”

Entering overseas markets provides challenges for firms, especially for those with little international experience. These obstacles can be compounded for manufacturers of advanced machinery, as previous research suggests that a physical presence is necessary for the successful implementation of their products in export markets. One way for producers to address this issue is to participate in trade fairs, which enables a physical presence of staff and machinery to be established. Evidence from a survey of Korean machinery producers at a recent trade fair suggests that a physical presence is related to the importance that firms ascribe to exports and to the role of trade fairs in new sales.     

Polybrominated diphenyl ethers do not affect metamorphosis but alter the proteome of the invasive slipper limpet Crepidula onyx

Man-made polybrominated diphenyl ethers (PBDEs) used as flame retardants in various consumer products may be harmful to marine organisms. Larvae of some marine invertebrates, especially invasive species, can develop resistance to PBDEs through altered protein expression patterns or proteome plasticity. This is the first report of a proteomics approach to study BDE-47 induced molecular changes in the invasive limpet Crepidula onyx. Larvae of C. onyx were cultured for 5 days (hatching to metamorphosis) in the presence of BDE-47 (1 μg L⁻¹). Using a 2-DE proteomics approach with triple quadrupole and high-resolution TOF-MS, we showed that BDE-47 altered the proteome structure but not the growth or metamorphosis of C. onyx larvae. We found eight significant differentially expressed proteins in response to BDE-47, deemed the protein expression signature, consisting of cytoskeletal, stress tolerance, metabolism and energy production related proteins. Our data suggest C. onyx larvae have adequate proteome plasticity to tolerate BDE-47 toxicity.     

A comprehensive program for countermeasures against potentially hazardous objects (PHOs)

At the hundredth anniversary of the Tunguska event in Siberia it is appropriate to discuss measures to avoid such occurrences in the future. Recent discussions about detecting, tracking, cataloguing, and characterizing near-Earth objects (NEOs) center on objects larger than about 140 m in size. However, objects smaller than 100 m are more frequent and can cause significant regional destruction of civil infrastructures and population centers. The cosmic object responsible for the Tunguska event provides a graphic example: although it is thought to have been only about 50 to 60 m in size, it devastated an area of about 2000 km². Ongoing surveys aimed at early detection of a potentially hazardous object (PHO: asteroid or comet nucleus that approaches the Earth’s orbit within 0.05 AU) are only a first step toward applying countermeasures to prevent an impact on Earth. Because “early” may mean only a few weeks or days in the case of a Tunguska-sized object or a longperiod comet, deflecting the object by changing its orbit is beyond the means of current technology, and destruction and dispersal of its fragments may be the only reasonable solution. Highly capable countermeasures- always at the ready—are essential to defending against an object with such short warning time, and therefore short reaction time between discovery and impending impact. We present an outline for a comprehensive plan for countermeasures that includes smaller (Tunguska-sized) objects and long-period comets, focuses on short warning times, uses non-nuclear methods (e.g., hyper-velocity impactor devices and conventional explosives) whenever possible, uses nuclear munitions only when needed, and launches from the ground. The plan calls for international collaboration for action against a truly global threat.     

Elevated naturally occurring arsenic in a semiarid oxidizing system, Southern High Plains aquifer, Texas, USA

High groundwater As concentrations in oxidizing systems are generally associated with As adsorption onto hydrous metal (Al, Fe or Mn) oxides and mobilization with increased pH. The objective of this study was to evaluate the distribution, sources and mobilization mechanisms of As in the Southern High Plains (SHP) aquifer, Texas, relative to those in other semiarid, oxidizing systems. Elevated groundwater As levels are widespread in the southern part of the SHP (SHP-S) aquifer, with 47% of wells exceeding the current EPA maximum contaminant level (MCL) of 10 μg/L (range 0.3–164 μg/L), whereas As levels are much lower in the north (SHP-N: 9%  As MCL of 10 μg/L; range 0.2–43 μg/L). The sharp contrast in As levels between the north and south coincides with a change in total dissolved solids (TDS) from 395 mg/L (median north) to 885 mg/L (median south). Arsenic is present as arsenate (As V) in this oxidizing system and is correlated with groundwater TDS (Spearman’s ρ = 0.57). The most likely current source of As is sorbed As onto hydrous metal oxides based on correlations between As and other oxyanion-forming elements (V, ρ = 0.88; Se, ρ = 0.54; B, ρ = 0.51 and Mo, ρ = 0.46). This source is similar to that in other oxidizing systems and constitutes a secondary source; the most likely primary source being volcanic ashes in the SHP aquifer or original source rocks in the Rockies, based on co-occurrence of As and F (ρ = 0.56), oxyanion-forming elements and SiO₂ (ρ = 0.41), which are found in volcanic ashes. High groundwater As concentrations in some semiarid oxidizing systems are related to high evaporation. Although correlation of As with TDS in the SHP aquifer may suggest evaporative concentration, unenriched stable isotopes (δ²H: −65 to −27; δ¹⁸O: −9.1 to −4.2) in the SHP aquifer do not support evaporation. High TDS in the SHP aquifer is most likely related to upward movement of saline water from the underlying Triassic Dockum aquifer. Mobilization of As in other semiarid oxidizing systems is caused by increased pH; however, pH in the SHP aquifer is near neutral (10–90 percentiles, 7.0–7.6). Although many processes, such as competitive desorption with SiO₂, VO₄, or PO₄, could be responsible for local mobilization of As in the SHP aquifer, the most plausible explanation for the regional As distribution and correlation with TDS is the counterion effect caused by a change from Ca- to Na-rich, water as shown by the high correlation between As and Na/(Ca)^0.5 ratios (ρ = 0.57). This change in chemistry is related to mixing with saline water that moves upward from the underlying Dockum aquifer. This counterion effect may mobilize other anions and oxyanion-forming elements that are correlated with As (F, V, Se, B, Mo and SiO₂). Competition among the oxyanions for sorption sites may enhance As mobilization. The SHP case study has similar As sources to those of other semiarid, oxidizing systems (original volcanic ash source followed by sorption onto hydrous metal oxides) but contrasts with these systems by showing lack of evaporative concentration and pH mobilization of As but counterion mobilization of As instead in the SHP-S aquifer.     

Chemical fractionation of metals in freshly deposited marine estuarine sediments of sundarban ecosystem,India

Sediment metal profiles were carefully examined for their distribution, chemical fractions, and mobility in three major marine-estuarine transects in the world’s largest mangrove (Sundarban) ecosystem because anthropogenic influences had been very often noticed. The level of pollutants was determined by CF and PLI. Metal contents in the freshly deposited sediment of Hugli transect were relatively high (Pb, Fe, Zn, Mn, Ni, and Co) in comparison to Matla and Saptamukhi due to lithogenic contribution from large catchments area (8 × 10⁵ km²). Principal component analysis and correlation coefficient revealed that the concentrations of metals were mainly governed by the variability of the sediment properties. Sediment was subjected to sequential chemical extractions to delineate metal fractions, namely exchangeable, carbonate, Fe–Mn oxide, organic, and residual. This indicated a valuable insight into the geochemical mode of the metal retention and their environmental behavior. Single extraction did not help significantly to explain the metal profiling.