Chemical Weathering of Granite in Ice and Its Implication for Weathering in Polar Regions

Abstract

Recently, it has been reported that some chemical reactions are enhanced in below-freezing conditions. Despite the high denudation typical of polar regions, chemical weathering that occurs under ice has not been investigated. In this study, we investigated the dissolution of granite in ice. The mixture of granite and deionized water (DW) or solution adjusted to pH 2 or 3 was split into two groups: the test group was frozen at −20 °C, while the control was maintained at room temperature. After 29 days of batch experiments, the filtrate was analyzed to measure the concentrations of cations and silica. The filtered powder was analyzed to investigate the mineral compositions and crystallinities of the granite before and after the experiments. Despite the low temperature, a significant quantity of cations (Na+, K+, Mg2+, Ca2+) were dissolved out, even from the ice samples. During X-ray diffraction (XRD) analysis, the decreased crystallinities of granite in ice samples were identified regardless of the pH condition. To verify the observed freeze concentration effect, the concentration of granite in the ice grain boundaries was observed using optical microscopy with a cold chamber. The low concentration of silica in the ice samples could explain the silica anomaly in polar regions. This study also provides a new perspective for the dissolution mechanism in polar regions.

Fractionation of organic C, nutrients, metals and bacteria in peat porewater and ice after freezing and thawing

“…Unlike eld observations that incorporate multiple parameters capable of impacting transformation of solutes over the soil column, laboratory experiments allow for more rigorous assessment of governing factors and quanti cation of freezing/thawing effects (Schwamborn et al, 2012;Chen et al, 2016;Spencer et al, 2017;Jiang et al, 2018;Kim and Choi, 2018;Chung et al, 2020;Savenko et al, 2020).…”

Mecanismos de degradação e patologias da rocha natural – breve revisão sobre um amplo tópico

“…A deterioração da rocha natural causada pela ação de sais solúveis e pela formação de gelo encontra-se bem documentada nos textos de Zezza e Macrí (1995), Doehne (2002), Charola (2000), Rodríguez-Navarro e Doehne (1999), Espinosa e Scherer (2008) e Matsuoka e Murton (2008) Chung et al (2020), entre outros.…”

Frozen Clay Minerals as a Potential Source of Bioavailable Iron and Magnetite

“…3−5 With regard to chemical reactions with minerals, the chemical weathering of granite proceeds in both a frozen state and the aqueous phase. 6 Moreover, iron oxide dissolution can be enhanced in ice in the presence of organic acids. 7 The freeze concentration effect, producing an increased concentration of solutes at ice grain boundaries during ice formation, has been suggested as the main cause of these enhanced chemical reactions in ice.…”

“…Ice has also been suggested to play a key role in the destruction of ozone in the stratosphere in polar regions . The transformation of halogen species, including iodine and bromine, into reactive forms in sea ice or snowpacks and their release into the atmosphere in polar regions have also been reported. − With regard to chemical reactions with minerals, the chemical weathering of granite proceeds in both a frozen state and the aqueous phase . Moreover, iron oxide dissolution can be enhanced in ice in the presence of organic acids .…”