Heavy metal content in the beach sediment with respect to contamination levels and sediment quality guidelines: a study at Kalpakkam coast,southeast coast of India

Socioeconomic developments and industrialization exert tremendous impact on beaches which is often neglected. Heavy metal (Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb) contents were estimated in the intertidal region from Kalpakkam to Mamallapuram (20 km), southeast coast of India covering seven locations. To evaluate the level of contamination of these metals; enrichment factor (EF), geoaccumulation index (I _geo), contamination factor (CF), pollution load index (PLI) and modified degree of contamination (mCd) were applied. The results were also compared with the sediment quality guidelines (SQGs) to find out the eco-toxicity level. Metal contents in the beach sediment were observed in the order: Fe > Al > Mn > Cr > Cu > Ni > Zn > Pb > Co > Cd. Grain size distribution showed medium to coarse nature of the sediment. Significant positive correlation was found among the metals indicating their common source of input. Based on EF, minor enrichment of Mn and Zn and moderately severe to severe enrichment of Cr, Cu, Pb and Cd were observed which was further confirmed by I _geo and CF values. Moreover, Mamallapuram showed a very high CF value for Cd (>6) indicating very high contamination accountable to anthropogenic sources. PLI and mCd in all the stations indicated unpolluted nature except M1 where the values pointed moderate degree of contamination. As per the SQGs, Ni and Cr values exceeded the probable effect limit value implying that these metals can have adverse impacts. None of the metals exceeded the effect range median indicating that the beach sediment is not very toxic.     

Strong ground motion parameters of the 18 September 2011 Sikkim Earthquake Mw = 6.9 and its analysis: a recent seismic hazard scenario

Natural Hazards - The 18 September 2011 earthquake in Sikkim was one the most devastating earthquake in Sikkim Himalaya in India–Asia collision boundary. The source characteristic of this...     

Distribution of geochemical fractions of phosphorus and its ecological risk in sediment cores of a largest brackish water lake,South Asia

The current study focuses on the vertical profile of different geochemical fractions of phosphorus-loosely bound(Lo–P),aluminium bound(Al–P),iron bound(Fe–P),calcium bound(Ca–P),and organic bound phosphorus(O–P)along with ecological risk assessment of sediment cores from Chilika Lake,eastcoast of India.The percentage contribution of the different fractions to the sedimentary phosphorus in the sediment column of the whole lake are on the order:O–P(33.2%)>Ca–P(20.3%)>Fe–P(18%)>Al–P(6.7%)>Lo–P(0.35%).The Phosphorus Pollution Index(PPI)revealed the contamination of lake sediment with phosphorus.The principal component and cluster analyses highlighted the anthropogenic contribution of phosphorus.The negative loading of Ca–P with Ca points towards its origin from marine shells.The discriminate analysis showed that the variables like Ca–P,bio-available phosphorus(BAP),and pH were able to effectively discriminate the sectors in a significant manner.     

Mumbai 2005, Bihar 2008 Flood Reflected in Mass Changes Seen by GRACE Satellites

Gravity Recovery And Climate Experiment (GRACE) satellites were launched on March 17 2002 to derive with unprecedented accuracy, estimates of the global high resolution model of the earth’s gravity field. Local gravity changes with change in mass or mass redistribution. The mass changes can be due to hydrological events, seismic events or postglacial rebound, majorly. GRACE is sensitive to changes at large spatial scale since the resolution of GRACE is 400 km. Hydrological activities over basins provide sufficient mass changes to be detected by GRACE. In this research paper the discussion would be about two major flooding events in India, one being the 2005 monsoon flooding in Mumbai and nearby states and other being flood experienced by Bihar in 2008. The GRACE data is in the form of matrix consisting spherical harmonic coefficients. These coefficients are processed to obtain mass changes in terms of equivalent water height at a spatial scale of 400 km. The strategy of analysis is also discussed which need to be followed depending upon limitations of GRACE observation and requirement of application, here in this case application is flood induced mass change detection. Time-series and residual plots are generated and they show the flooding events for the concerned area as outliers. Better visualisation is obtained by residual plot, if there is a trend or systematic behaviour in time-series. This work points towards the qualitative capability of GRACE to detect flooding events at large spatial scale. Quantitative analysis requires in-situ data over the period of GRACE which is not possible for the cases discussed here.     

Clay Minerals in Soils as Evidence of Holocene Climatic Change, Central Indo-Gangetic Plains, North-Central India

Clay mineral assemblages of a soil chrono-association comprising five fluvial surface members (QGH1 to QGH5) of the Indo-Gangetic Plains between the Ramganga and Rapti rivers, north-central India, demonstrate that pedogenic interstratified smectite–kaolin (Sm/K) can be considered as a potential indicator for paleoclimatic changes during the Holocene from arid to humid climates. On the basis of available radiocarbon dates, thermoluminescence dates, and historical evidence, tentative ages assigned to QGH1 to QGH5 are <500 yr B.P., >500 yr B.P., >2500 yr B.P., 8000 TL yr B.P., and 13,500 TL yr B.P., respectively. During pedogenesis two major regional climatic cycles are recorded: relatively arid climates between 10,000–6500 yr B.P. and 3800–? yr B.P. were punctuated by a warm and humid climate. Biotite weathered to trioctahedral vermiculite and smectite in the soils during arid conditions, and smectite was unstable and transformed to Sm/K during the warm and humid climatic phase (7400–4150 cal yr B.P.). When the humid climate terminated, vermiculite, smectite, and Sm/K were preserved to the present day. The study suggests that during the development of soils in the Holocene in alluvium of the Indo-Gangetic Plains, climatic fluctuations appear to be more important than realized hitherto. The soils older than 2500 yr B.P. are relict paleosols, but they are polygenetic because of their subsequent alterations.