Entity

Time filter

Source Type

Lausanne, Switzerland

Larras F.,French National Institute for Agricultural Research | Larras F.,University of Savoy | Larras F.,CNRS Interdisciplinary Laboratory for Continental Environments | Rimet F.,French National Institute for Agricultural Research | And 8 more authors.
Environmental Science and Pollution Research | Year: 2016

Chemical monitoring revealed a regular decrease in herbicide concentration in Lake Geneva since last decades that may be linked to an ecotoxic restoration of nontarget phytoplanktonic communities. The Pollution-induced community tolerance (PICT) approach was tested as a tool to monitor the ecotoxic restoration of Lake Geneva for herbicides from 1999 to 2011. We conducted monthly assessments in 1999 and in 2011 for the tolerance of the phytoplankton communities to two herbicides (atrazine and copper), using PICT bioassays. The taxonomical composition of the communities was determined on the same collecting dates. The herbicide concentration decrease during the 12 years significantly influenced the composition of communities. The PICT monitoring indicated that a significant tolerance decrease in the community to both herbicides accompanied the herbicide concentration decrease. PICT measurements for atrazine and copper also changed at the intra-annual level. These variations were mainly due to community composition shifts linked to seasonal phosphorus and temperature changes. PICT monitoring on a seasonal basis is required to monitor the mean tolerance of communities. PICT appeared to be a powerful tool that reflected the toxic effects on environmental communities and to monitor ecotoxic ecosystem restoration. © 2015, Springer-Verlag Berlin Heidelberg. Source


Font E.,University of Lisbon | Ponte J.,University of Lisbon | Adatte T.,ISTE | Fantasia A.,ISTE | And 2 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2016

The Deccan Volcanic Province (DVP) was built up by three major phases of eruptions; the most voluminous of which, the Deccan Phase 2, encompassed the Cretaceous-Palaeogene (KT) boundary. Deccan eruptions have been implicated as a contributor to the end-Cretaceous mass extinction, however, mechanism by which volcanic activity affected biota remains poorly understood. We applied a combination of rock magnetic techniques scanning electron microscopy to characterize mineral assemblages of three sections of intertrappean lacustrine sediments from the north-western Maharashtra Deccan Volcanic Provinces. Our results indicate that in sediments deposited during the early stages of the Deccan Phase 2, the Daïwal River and Dhapewada sequences, iron-bearing mineral association is dominated by detrital iron oxides (magnetite and hematite) sourced from the weathering of the surrounding basaltic bedrocks, with minor contribution form authigenic iron sulphides (framboidal pyrite, pyrrhotite and/or greigite). The sediments deposited during the final stages of Phase 2 (the Podgawan sequence) differ significantly in their characteristics. In particular, the Podgawan sediments have 1) very low magnetic susceptibility values, but higher terrigenous fraction (clays and shales) content; 2) more complex assemblage of magnetic minerals, 3) ubiquitous presence of Fe-Ca-Ce vanadates; and 4) unusual lithological variations in the middle part of the section (represented by a charcoal-rich level that is capped by a red clay layer containing fossilized bacterial colonies). We suggest that these unusual characteristics reflect increased acidity in the region during the deposition of the Podgawan sequence, likely due to cumulative effects of volcanic aerosols released during the Deccan Phase 2 eruptions. The combination of these features may be used to recognize episodes of increased acidity in the geological record. Our results also contribute to understanding of local vs. global effects of the Deccan volcanism. © 2015 Elsevier B.V. Source


Larras F.,University of Savoy | Larras F.,CNRS Interdisciplinary Laboratory for Continental Environments | Rimet F.,University of Savoy | Gregorio V.,ISTE | And 4 more authors.
Environmental Science and Pollution Research | Year: 2015

Chemical monitoring revealed a regular decrease in herbicide concentration in Lake Geneva since last decades that may be linked to an ecotoxic restoration of nontarget phytoplanktonic communities. The Pollution-induced community tolerance (PICT) approach was tested as a tool to monitor the ecotoxic restoration of Lake Geneva for herbicides from 1999 to 2011. We conducted monthly assessments in 1999 and in 2011 for the tolerance of the phytoplankton communities to two herbicides (atrazine and copper), using PICT bioassays. The taxonomical composition of the communities was determined on the same collecting dates. The herbicide concentration decrease during the 12 years significantly influenced the composition of communities. The PICT monitoring indicated that a significant tolerance decrease in the community to both herbicides accompanied the herbicide concentration decrease. PICT measurements for atrazine and copper also changed at the intra-annual level. These variations were mainly due to community composition shifts linked to seasonal phosphorus and temperature changes. PICT monitoring on a seasonal basis is required to monitor the mean tolerance of communities. PICT appeared to be a powerful tool that reflected the toxic effects on environmental communities and to monitor ecotoxic ecosystem restoration. © 2015 Springer-Verlag Berlin Heidelberg Source


Brightson P.,Vellichanthai | Baskar G.,IRTT | Basil Gnanappa S.,ISTE
Life Science Journal | Year: 2013

Concrete is widely used in structural engineering with its high compressive strength, low cost and abundant raw material. But common concrete has some shortcomings, for example, low tensile and flexural strength, poor toughness, high brittleness, and so on that restrict its application. To overcome these deficiencies, additional materials are added to improve the performance of concrete. A Nano admixture is a composite material that has been developed in recent years. It has been successfully used in construction with its excellent flexural tensile strength, permeability and so on. An attempt has been made in this paper to provide the advantages and benefits of using nano admixtures in concrete for a variety of applications. The use of admixtures help in modifying properties of concrete both in plastic and hardened stage and thus results into a more durable concrete. The main purpose of this investigation is to study the effects of nano clay on the compressive, split tensile and flexural strength of concrete. Concrete specimens were casted with and without nano clay and tested after 7 and 28 days water curing. Experimental results show that addition of admixtures improves the performance of concrete. Source

Discover hidden collaborations