Concentration of Trace Metals and Biochemical Alterations in Various Species of Fishes along the West Coast of India

Ocean Science Journal - This study seeks to evaluate levels of seven trace metals (Cr, Mn, Fe, Cu, Zn, Pb and Hg) and biochemical (proteins, lipids and carbohydrates) alterations in muscle tissue...     

Characterization of abrasion surfaces in rock shore environments of NW Spain

Despite the recent upsurge in rock coast research, many aspects of abrasion and their relationships to other processes remain poorly understood. In this paper, mechanisms subsumed under the general term abrasion were investigated at the beaches of Oia and Sartaña along the Galician coast of NW Spain, in particular at the micro- to meso-scale (mm–cm). Relationships between abrasion and mechanical rock strength served to explore feedbacks between weathering and abrasion on rock coasts, based on measurements of rock surface strength by means of the Equotip (Proceq) method, and stereomicroscope analyses of rock surfaces undergoing varying degrees of abrasion. The results suggest that (1) abrasion along near-vertical rock surfaces leads to a decrease in rock strength with elevation above the top of the basal sediment layer, (2) abrasion processes encompass two different modes, namely, the wave-induced sweeping and dragging of sand and gravel, and the projection of clasts against rock surfaces, each mode depending predominantly on the grain size of the abrasive agent, and (3) the two abrasion modes produce different rock surfaces whose roughness is strongly influenced by the properties of diverse minerals, in particular fracture and cleavage.     

Implementation and integrated numerical modeling of a landslide early warning system: a pilot study in Colombia

Landslide early warning systems (EWS) are an important tool to reduce landslide risks, especially where the potential for structural protection measures is limited. However, design, implementation, and successful operation of a landslide EWS is complex and has not been achieved in many cases. Critical problems are uncertainties related to landslide triggering conditions, successful implementation of emergency protocols, and the response of the local population. We describe here the recent implementation of a landslide EWS for the Combeima valley in Colombia, a region particularly affected by landslide hazards. As in many other cases, an insufficient basis of data (rainfall, soil measurements, landslide event record) and related uncertainties represent a difficult complication. To be able to better assess the influence of the different EWS components, we developed a numerical model that simulates the EWS in a simplified yet integrated way. The results show that the expected landslide-induced losses depend nearly exponentially on the errors in precipitation measurements. Stochastic optimization furthermore suggests an increasing adjustment of the rainfall landslide-triggering threshold for an increasing observation error. These modeling studies are a first step toward a more generic and integrated approach that bears important potential for substantial improvements in design and operation of a landslide EWS.     

Enriched Subcontinental Lithospheric Mantle in the Northern Part of the South Indian Granulite Terrain: Evidence from Yelagiri and Sevattur Syenite Plutons, Tamil Nadu, South India

In the southern part of the Indian Peninsula, there are a number of alkaline plutons of Proterozoic age. In the northern part of the South Indian granulite terrain, the Yelagiri (syenite, pyroxenite) and Sevattur (syenite, pyroxenite, carbonatite) plutons intrude Archaean epidote-hornblende gneisses. Geochemical and isotopic characteristics of the Yelagiri and Sevattur plutons indicate that the syenitic magmas formed from highly differentiated mantle-derived alkali basalts. The Yelagiri and Sevattur syenites are characterized by evolved Sr and Nd isotopic compositions, pronounced enrichment in LILE and large negative Nb anomalies. Trace element and Sr-Nd isotope characteristics of the Yelagiri and Sevattur syenites are similar to those of the subduction-related alkaline rocks. The scarcity of geological evidence for subduction activity at the time of syenite intrusion during Neoproterozoic does not support a link between the alkaline magmatism and subduction. However, our data are consistent with the model of derivation of the Yelagiri and Sevattur syenites from the subcontinental lithospheric mantle, which was previously enriched by slab derived component. The geochemical and isotopic signatures of other mantle-derived intrusive rocks in the northern part of the South Indian granulite terrain with ages ranging from ca. 2.5 Ga to 0.75 Ga also support the above idea.     

A transition from CMIP3 to CMIP5 for climate information providers: the case of surface temperature over eastern North America

The release of new data constituting the Coupled Model Intercomparison Project—Phase 5 (CMIP5) database is an important event in both climate science and climate services issues. Although users’ eagerness for a fast transition from CMIP3 to CMIP5 is expected, this change implies some challenges for climate information providers. The main reason is that the two sets of experiments were performed in different ways regarding radiative forcing and hence continuity between both datasets is partially lost. The objective of this research is to evaluate a metric that is independent of the amount and the evolution of radiative forcing, hence facilitating comparison between the two sets for surface temperature over eastern North America. The link between CMIP3 and CMIP5 data sets is explored spatially and locally (using the ratio of local to global temperatures) through the use of regional warming patterns, a relationship between the grid-box and the global mean temperature change for a certain time frame. Here, we show that local to global ratios are effective tools in making climate change information between the two sets comparable. As a response to the global mean temperature change, both CMIP experiments show very similar warming patterns, trends, and climate change uncertainty for both winter and summer. Sensitivity of the models to radiative forcing is not assessed. Real inter-model differences remain the largest source of uncertainty when calculating warming patterns as well as spatially-based patterns for the pattern scaling approach. This relationship between the datasets, which may escape users when they are provided with a single radiative forcing pathway, needs to be stressed by climate information providers.     

Summer circulation patterns related to the upper tropospheric vortices over the Tropical South Atlantic

Summary Daily 200-hPa relative vorticity data have been used to study the dominant patterns related to the cyclonic vortices over the South Atlantic Ocean in the vicinities of northeast Brazil, during the 1980–1989 period. Reference modes were obtained through empirical orthogonal function (EOF) analysis of the 200-hPa filtered vorticity anomalies over northeast Brazil, considering all the southern hemisphere (SH) summers within the study period. The amplitude time series of the first reference mode, separately for each SH summer, was correlated with the corresponding filtered vorticity anomalies in a larger area extending from 20°N to 40°S and between 120°W and 20°W. The correlation patterns feature a wave-like structure along eastern South America, with three main centers: the first one, over the South Atlantic off the northeast Brazil coast, is associated with the cyclonic vortices; the second one, over eastern Brazil, represents the corresponding anomalously amplified ridges; and the third one, over southern Brazil/Uruguay, is related to the equatorward incursions of midlatitude upper level troughs. This wave-like pattern is consistent with the vortex formation mechanism suggested in previous works. Another wave-like pattern southwest-northeast oriented is evident over the tropical southeastern Pacific, for some years. The internannual variability of these patterns is discussed in this paper.With 9 Figures