Search results for "Weathering"

The role of pedogenic overprinting in the obliteration of parent material in some polygenetic landscapes of Sicily (Italy)

2016

Abstract Many soils older than the Holocene have experienced several changes, and possess properties that may be due to the complex effect of several stages of soil development; these soils are called polygenetic. It is still rather unclear, however, if, as time elapses, pedogenic processes tend to diverge generating different soils, or converge towards increasingly similar soils. We studied five pedons (37°60′N, 13°90′E) exposed to present weathering simultaneously since the Holocene but located on Upper Miocene or Holocene parent material. Their XRD and FTIR clay mineralogy reveal an overall homogeneity; smectites, calcite and gypsum reach the thermodynamic equilibrium, a slight undersatu…

An erratic dropstone of granodiorite with a water-escape structure from a Weichselian terrace along the River Gauja (NE Latvia)

2016

Abstract A river terrace of the River Gauja (Latvia), built of Weichselian glaciolacustrine deposits, contains a large number of erratic boulders from the Fennoscandian Shield. These erratic boulders include several types of granites and granodiorites. Some of the granodiorites are so strongly weathered that they fall apart into mm-sized grains of individual minerals when it is attempted to take them out of the host sediment. This strongly weathered nature makes them physically comparable to unconsolidated sand. A consequence is that they may be subjected to soft-sediment deformation. The erratic granodiorite boulder under study here is the first described to show such a soft-sediment defor…

MODELLING OF WATER-ROCK INTERACTIONS IN CARBONATE AQUIFERS: INSIGHTS FROM A CASE STUDY IN THE MADONIE AREA (SICILY)

2009

Dissolved silica in the Garonne River waters : changes in the weathering dynamics

2000

The major ion chemistry of the Garonne River is indicative of seasonal variations in the weathering dynamics of the drainage basin. Using the geochemical model MEGA for calculation of the contribution of atmospheric CO2 to the total bicarbonate fluxes exported by the Garonne River allows estimations of the concentrations of the major dissolved elements that originate from silicate- and carbonate-rock weathering. The molecular ratio SiO2/Al2O3 was calculated for the 1989–1992 period to identify the main type of weathering in the Garonne River, and montmorillonite was shown to be the major mineral occurring in the weathering products. The seasonal variations of the SiO2/Al2O3 ratio also showe…

THE BIO-PROTECTIVE ROLE OF A BIOLOGICAL ENCRUSTATION

2014

Benthic organisms can form a persistent biological layer that mediates processes of rock deterioration and limits the degradation of the underlying surface. In this study we investigated the bioprotective potential of barnacle encrustations against salt weathering processes, and discuss their possible role in enhancing the durability of coastal engineering structures

Influence of HCl pretreatment and organo-mineral complexes on laser diffraction measurement of loess–paleosol-sequences

2016

Abstract The influence of different sample pretreatment methods on grain size distributions in particle size analysis has been subject to controversial discussions. Standard sample preparation typically comprises the disaggregation of aggregated and agglomerated particles into single primary particles, i.e., the organic binding material is oxidized by hydrogen peroxide (H2O2) and the contained carbonates are dissolved by hydrochloric acid (HCl). The aim of this study is to evaluate the effects of HCl treatment on grain size analyses of Late Pleistocene and Holocene loess–paleosol-sequences investigated by a Beckman Coulter LS 13320 laser particle analyzer. For this purpose, samples from two…

A study of weathered coal spectroscopic properties

2017

Abstract Current coal industry causes significant environmental pollution and the most air pollution deaths in the world, making the development of new eco-friendly applications one of the top priorities. Coal contains up to 50 % humic substances (HS), the majority of which is humic acid (HA). HA is well known for its beneficial properties and thus compounds extracted from coal can be used to develop new applications. To address this issue, we assessed structural composition of coal HS by measuring their spectroscopic properties. As the result, obtained spectra can be used to identify information about the molecules and thus allowing describing the composition of HS. The purpose of this stu…

Stable Cu isotope fractionation in soils during oxic weathering and podzolization

2011

Abstract Copper stable isotope ratios are fractionated during various biogeochemical processes and may trace the fate of Cu during long-term pedogenetic processes. We assessed the effects of oxic weathering (formation of Cambisols) and podzolization on Cu isotope ratios (δ65Cu). Two Cambisols (oxic weathered soils without strong vertical translocations of soil constituents) and two Podzols (soils showing vertical translocation of organic matter, Fe and Al) were analyzed for Cu concentrations, partitioning of Cu in seven fractions of a sequential extraction and δ65Cu values in bulk soil. Cu concentrations in the studied soils were low (1.4–27.6 μg g−1) and Cu was mainly associated with stron…

The role of hydrology on enhanced weathering for carbon sequestration II. From hydroclimatic scenarios to carbon-sequestration efficiencies

2021

Abstract Enhanced weathering (EW) scenarios are analyzed using the model presented in Cipolla et al. (2020). We explore the role of different hydroclimatic forcing on carbon-sequestration efficiencies. We also investigate whether increasing soil carbon content improves weathering conditions. We link olivine weathering rates to pH variations and quantify the suitability of hydroclimatic regimes to EW, based on rainfall intensity and frequency. The results show that the amount of CO 2 reacting with olivine and ending up in solution in the form of HCO 3 − and CO 3 2 − increases with mean annual precipitation (MAP) up to 2000 mm, but then tapers off for higher MAPs. On the contrary, the sequest…

Photo-re-stabilisation of recycled post-consumer films from greenhouses

2004

The photo-oxidation behaviour of recycled post-consumer films from greenhouses has been studied in order to evaluate the environmental resistance of these secondary materials and the effect of some stabilising agents. The presence of the UV absorber slows down the weathering of the post-consumer materials. After about 1000 h of accelerated weathering the unstabilised post-consumer material becomes brittle, while the re-stabilised post-consumer film becomes fragile only after about 1500 h. A synergistic effect is observed when an antioxidant and an UV stabiliser are added. Indeed, in this case, the recycled material is not brittle even after more than 1700 h. These last results can be probab…