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Data on the mineralogy and geochemistry of rare earth elements (REE + Y) in water, suspended matter and stratified sediment cores from different parts of Lake Onego are presented. The study finds that the dissolved REE + Y in the water from different areas of Lake Onego have common features: (1) a maximum in the area of middle rare earth elements (MREE), (2) a distinct negative Ce anomaly and (3) a positive Eu anomaly. Comparison of the average concentration of elements in the stratified core of the bottom sediments and particulate matter (from the filters and sedimentation traps) from different parts of Lake Onego and the distribution of REE + Y do not reveal any significant differences. The trend of the REE + Y distribution for samples from the South Onego completely coincide the REE + Y distribution in siltstones and sandstones of the Russian Platform Scale Composite (RPSC). In the water area of Lake Onego from south to north, a well-defined trend of changes in REE + Y patterns relative to the RPSC is revealed, with depletion by heavy REE + Y and gradual enrichment by light rare earth elements (LREE). Geochemical and mineralogical data confirm our hypothesis of a significant reformatting of the catchment basin of the Onego Ice Lake in the Late Pleistocene. During the formation of the preglacial lake, a significant part of the catchment area was located south of Lake Onego and is mainly represented by Russian Platform sedimentary rocks. Due to the degradation of the Last Glacier from the Lake Onego depression and the nearby territories, the catchment area changed of its southern and south-eastern sections. Today the composition of the modern sedimentary matter entering Lake Onego is determined by mixing clusters from two geochemically contrasting feeding areas: loose sediments formed by the repeatedly re-deposited products of the weathering of the Fennoscandian Shield's crystalline rock massifs, including Phanerozoic sediments; and to a lesser extent the sediments of the sedimentary cover of the Russian Platform, except the bottom sediments of the South Onego, in which Phanerozoic sedimentary formations have completely predominated throughout the lake's development.

The geochemical composition and magnetic susceptibility (MS) of three sections (Weinan, Jingchuan and Jingbian) in the central Chinese Loess Plateau, located along a north-south climate gradient, were analyzed at high resolution in order to reconstruct changes in weathering intensity and hence Asian monsoon evolution during the Holocene. The results show distinct differences in element composition between the loess and paleosol layer, as well as spatial differences which reflect changes in mean annual temperature and annual precipitation along the climatic gradient. The measured major element compositions, combined with the results of previous research, indicate that the provenance of the Holocene loess-paleosol sequences in the central Chinese Loess Plateau was constant over time and space. The degree of chemical weathering in the study area is relatively weak and at an intermediate weathering stage. Based on a magnetic susceptibility age model, the East Asian summer monsoon changes recorded by the loess-paleosol sequences show a distinct two-stage pattern of evolution, with a gradual increase during 13.1–8.5 ka and a gradual decrease thereafter. Comparison of the results with climate records from elsewhere indicates that the East Asian monsoon evolution was mainly controlled by changes in Northern Hemisphere summer insolation and ice sheets.

Subaerial physical, chemical and biological weathering processes are significant contributors to mountain landscape development worldwide, and over long time scales. This paper reports on pseudokarst features formed by different subaerial weathering processes on a high-elevation basalt plateau surface in the Maloti–Drakensberg mountains of eastern Lesotho, southern Africa. Different mesoscale landforms identified on this plateau surface include enclosed depressions (containing seasonal pools) that are morphologically similar to karstic solutional features. Such basalt pseudokarst landforms have not been previously described. This study uses field data on depression morphometry, sediments, water chemistry and rock surface hardness to explore the varied subaerial weathering and erosion processes contributing to pseudokarst depression development. Results show that physical, chemical and biological weathering and erosion processes in combination can impact on the basalt land surface in widening and deepening these depressions. An evolutionary model for pseudokarst depression development proposes that different weathering processes in combination within the ‘critical zone’ cause changes in depression morphology, and that there are significant feedbacks between bedrock, weathering, and the development of distinctive micromorphological forms. It is likely that similar pseudokarst landforms from other locations with non-carbonate substrates have been under-reported in the literature.

This work presents the systematic investigation of K contents and stable K isotopic compositions of surface waters, groundwater, wastewaters, suspended particles, bed sediments, and fertilizers in the Upper Mun Rive catchment, northeast Thailand. This area is of particular interest because its abundant potash deposits and intensive agricultural activities and urbanization, therefore this will improve our understanding whether the K isotope is robust enough to resist evaporite dissolution and anthropogenic disturbances on tracing silicate weathering in the highly weathered tropical region. The dissolved loads in surface waters and shallow groundwater display the large variation in δ41Kdiss values from −0.54‰ to +0.09‰ relative to suspended particles (−0.60‰ to −0.41‰), river bed sediments (−0.54‰ to −0.47‰), the upper continental crust (UCC, −0.44 ± 0.05‰), which agrees with the fact that 39K is preferentially retained in weathering products during silicate weathering. The wet and dry seasons difference ranging from −0.05‰ to +0.10‰ δ41K, which is slightly greater than our long-term analytical uncertainty of ±0.06‰. There is likely a limited K input from evaporites dissolution due to weak correlation between δ41Kdiss values and Cl concentrations or Cl/K ratios in the UMR and world rivers, while a major tributary Takhong River is clearly influenced by the contribution of domestic sewage with lower δ41K and higher δ15N values. Based on a mass balance of K budge, the dissolved K in the UMR is mostly (>90%) derived from silicate weathering in the unpolluted area, this is consistent with previous studies of large river basins, and the evaporite dissolution and other non-silicate sources may not strongly influence dissolved K and δ41Kdiss values in rivers, even in evaporite-rich catchment. Therefore, K isotopes cannot be used as lithological tracers in catchments, rather the K isotopic fractionation mainly occurs during silicate weathering, such as the formation of secondary minerals which favor light isotope. Hence, the mechanism of K isotopic fractionation linked to secondary minerals K uptake needs further consideration. Overall, these results clearly show that K isotopes could be an ideal indicator to constrain silicate weathering processes and anthropogenic inputs at catchment scale.

Dissolution and chemical weathering of carbonate rocks have complex effects on their mechanical properties, accelerating their rate of deterioration that can lead to early failure under external stresses. To investigate the effects of acidic solutions on the mechanical properties of inherently low-porosity karstic limestone, compression tests were performed on sound and weathered samples exposed to different corrosive environments and for different durations. The tested samples exhibited a general increase in porosity and decrease in peak strength and Young's modulus for higher acidity and exposure duration. To establish links between these mechanical changes and those at the micro-scale, microstructures and mechanisms of deformation were also studied. As indicators of the sample degradation, the distribution, orientation and intensity of the fractures in the tested samples and their twinning density were used. Based on these parameters, it was found that chemical erosion influences microcrack propagation, orientation, distribution and intensity, due to modification of the competence contrast between the constituents of the rock. These effects significantly influence the semi-brittle behaviour of the samples, including the distribution and intensity of microcracking and crystal plasticity.

This study aims to assess the water quality of the Mahananda River in Bangladesh and its suitability for drinking and agricultural uses. For water quality determination, 15 samples were collected from different sites of the Mahananda River to calculate Water Quality Index (WQI) and Entropy Water Quality Index (EWQI). Result shows that among different Hydrochemical parameters, carbonate and bicarbonate concentrations crossed the maximum limit in all the samples, while fluoride concentration exceeding in Sample-15 with the highest value found in Baroghoria area. From WQI result, water quality for the Baroghoria area was found unsuitable for drinking with WQI − 309.22, whereas another two samples of Mollikpur and Namo Neemgachi fall under ‘poor’ category with WQI of 184.49 and 198.99, respectively. EWQI reveals medium to excellent water quality. Result from different irrigation indices (Na%, sodium adsorption ratio (SAR), residual sodium carbonate (RSC), magnesium hazard (MH), total hardness, Kelly ratio (KR), and permeability index (PI) values) showed their suitability for irrigation. Principal component analysis (PCA) explained a total of 89.71% of variances in the dataset. Significant positive association within EC–Na, EC–sulfate, Ca–TH, nitrate–sulfate, etc., were reported indicating prominence in terms of both geogenic as well as anthropogenic processes such as silicate weathering and the release of untreated sewerage, respectively, which governs the water quality evolution in the study area. Cluster analysis (CA) classifies all water samples in five different clusters based on five different characteristics. Mahananda River water is found safe for both drinking and agricultural purposes, except for few samples near the dense human settlement areas. Result from this study is useful for decision makers to design management plans for the river water quality, environmental pollution and human well-being.

Within the eolian Lower Jurassic Navajo Sandstone, exposed in the Coyote Buttes area of Vermilion Cliffs National Monument in Arizona, a site (informally known as the “Dinosaur Dance Floor”) is reinterpreted as an enigmatic, modified (possibly pedogenic) eolian surface that was exposed and further modified and accentuated by modern weathering and erosion. The resultant surface is covered with small, shallow potholes or weathering pits, with no direct evidence of dinosaur activity.

Detailed investigation on hydrogeochemistry of hard rock terrains is important to identify the major geochemical processes and the source of ionic constituents in groundwater. The present study is carried out to understand the hydrogeochemistry of groundwater resources and the major hydrogeochemical processes, controlling the concentration of major ions in groundwater in the Kallada River Basin (KRB), South India. About 166 groundwater samples were collected from KRB during pre- and post-monsoon of 2016 for hydrogeochemical analysis. Most of the groundwater samples in KRB were within permissible limits of drinking water quality. The dominant groundwater types during pre-monsoon were Ca2+-Mg2+-Cl− which was changed to Na+-Cl− during post-monsoon. This is supported by the inverse relationship of depth of wells and change in EC during pre- and post-monsoon periods. Rock-water interaction processes such as reverse ion exchange and silicate weathering are major geochemical processes responsible for the hydrogeochemical signatures of KRB. The shallower wells (< 10 m) show strongest relation with the water types Na+-HCO3− and Ca2+-Mg2+-Cl− which have been changed to Na+-Cl− and Ca2+-Mg2+-HCO3− during post-monsoon. However, in deeper wells, Na+-Cl− is the dominant type of water during both seasons. The hierarchical cluster analysis displays different hydrogeochemical associations representing diverse physicochemical parameters both spatially and temporally. This study could shed light on diverse hydrogeochemical processes which are responsible for the hydrogeochemistry in KRB. Major hydrogeochemical processes in the Kallada River Basi

The accumulation of heavy metals in plant communities has been investigated in the maritime Antarctica but their sources are not clearly identified yet. Here we measured Pb isotope ratios in the mosses Sanionia uncinata (Hedw.) Loeske, soils and bedrocks on King George Island, South Shetland Islands, West Antarctica in order to elucidate the sources of Pb in the moss samples. The enrichment factor of Pb indicated that the moss samples near the research station and oil tank are highly enriched in Pb which is attributed to either leaded gasoline and/or Patagonian aeolian dust. However, Pb isotope ratios clearly indicated that leaded gasoline is the main source of Pb in the moss within 1 km from the station and that chemical weathering of soil and bedrock controls Pb content in the moss far from the station (over 1 km from the station). This study clearly demonstrated that Pb in plant communities, especially moss Sanionia uncinata (Hedw.) Loeske, on King George Island is mainly originated from a mixture of leaded gasoline and chemical weathering with a little effect of Patagonian aeolian dust.

This study was conducted to determine the characteristics of claystone at the Sebamban Syncline by carrying out geology—geomechanics and geochemistry approach. The aim of this is to provide the latest information on characteristics of claystone at the Sebamban Syncline. Results of the study showed that the provenance of Warukin claystone was from recycled orogen. This was corroborated by the geochemical data which stated that the claystone was composed by clay-sized quartz minerals. Clay-sized quartz minerals indicate that there has been a long process of transport and weathering of the quartz minerals that have high resistance, until they become clay-sized. The other geochemical data result is the absence of minerals from volcanic rocks that appear at the beginning of the Bowen series, which have fragile property. Mg is the fragile element that was not found and the mineral is an element binding in montmorillonite, so the presence of the montmorillonite in claystone of the Sebamban Syncline was also not found. Geomechanical data result shows that claystone had strength of around 100 kPa with internal friction angle of about 14° and cohesion of about 29 kPa.

Groundwater salinization is a global problem accounting for 11-30% of the world's irrigated areas. Luxor region in Upper Egypt is one of such areas affected by salinity. Multivariate statistics indicate that groundwater is affected by intermixed processes; mineralization (salinization), fertilization, domestic wastes, and meteoric recharge. Temporal change in salinity and hydrochemical facies during 1997-2017 revealed aquifer salinization, due to the dissolution of salts from overlain saline soil and marine deposits underneath as well as up-coning of deep saline water. Increasing salinity over time was statistically documented, exhibited temporally high significant differences (P

This study presents the landscape evolution of Lake Yakhi basin in eastern Mongolia where the lake plays an important role in the surface water resources. The multiple paleoshoreline features indicate wave-cut terraces, whereas the modern-day shorelines show that Lake Yakhi is at rapid northward regression. The paleo- and modern-day shorelines imply that the paleo-Lake Yakhi may have covered an extensive area with different hydrological conditions in the past. Lake Yakhi shows a decreasing trend in an area with a loss of ~62.2 km2 or 63.9% of the total area during the past five decades. The hydrological dynamics of Lake Yakhi during the last 50 years show its shift into a playa lake coinciding with the local climate changes in warming since 1987 and drying since 1992. In the lake's margin, mafic igneous provenance indicates a derivation from weathered granite and gneiss terrains on the oceanic island arc. However, in the lake's center, felsic igneous and quartzose sedimentary provenances show a derivation from the pre-existing sedimentary terrain on the active continental margin. Lake Yakhi sediments show the granite (felsic) and granite basalt (felsic to mafic) source rocks with mostly shale and arkose. The A-CN-K ternary plot shows that granites, granodiorites, and tonalities dominated in the lake sediments may have been transported from the source rocks enriched in plagioclase and feldspars. The weathering trend in the source area shows a low degree of chemical weathering and the chemical maturity shows a climatic shift from semiarid to arid climatic conditions in the Lake Yakhi basin. Cette étude présente l'évolution du paysage du bassin du lac Yakhi en Mongolie orientale. Les multiples caractéristiques de la paléosurface indiquent des terrasses découpées par les vagues, tandis que les lignes de rivage actuelles montrent que le lac Yakhi régresse rapidement vers le nord. Les lignes de rivage actuelles et les paléolignes de rivage impliquent que le paléo-lac Yakhi a pu couvrir une zone étendue avec différentes conditions hydrologiques dans le passé. Le lac Yakhi montre une tendance à la diminution de sa superficie, avec une perte de ~62,2 km2 (63,9 % de la superficie totale)sur les cinquante dernières années. La dynamique hydrologique du lac Yakhi au cours des 50 dernières années montre sa transformation en un lac de playa coïncidant avec le réchauffement du changement climatique local depuis 2001 et son assèchement depuis 1992. Dans la marge du lac, la provenance ignée mafique indique un dérivé de terrains granitiques et gneissiques altérés sur l'arc insulaire océanique. Cependant, au centre du lac, les provenances ignées felsiques et sédimentaires quartzeuses montrent une dérivation des terrains sédimentaires préexistants sur la marge continentale active. Les sédiments du lac Yakhi montrent les roches mères granitiques (felsiques) et basaltiques granitiques (felsiques à mafiques) avec principalement des schistes et des arkoses. Le tracé géochimique ternaire A-CN-K montre des granites, des granodiorites et des tonalites dominantes dans les sédiments lacustres transportés depuis les roches mères enrichies en plagioclase et en feldspath. La tendance à l'altération dans la zone source et la maturité chimique montrent un faible degré d'altération et un passage de conditions climatiques semi-arides à arides.

Antimony pollution in the groundwater of the Xikuangshan (XKS) antimony (Sb) mine area in China’s Hunan Province has attracted increasing attention. A total of 43 water samples were collected to help understand the hydrogeochemical characteristics, identify the Sb source, and evaluate the water–rock interactions of the Shetianqiao aquifer (SA). The Sb concentrations in shallow and deep SA water samples were 0.1–47.4 mg L−1 and 0.3–19.2 mg L−1, respectively. Stibnite oxidation and leaching from arsenic alkali residue mine wastes were the main Sb sources for the shallow SA water, whereas stibnite oxidation and stronger water–rock interaction were the predominant Sb sources for the deep SA water. The higher Sb concentration (> 10.0 mg L−1) in shallow SA water was predominantly induced by weathering of Sb-bearing minerals, evaporation/concentration effects, and cation exchange, whereas the higher Sb concentration in deep SA water was largely caused by weathering of Sb-bearing minerals, evaporation/concentration effects, ion exchange, and competitive adsorption. These findings provide a more detailed understanding of the geochemical behavior of Sb in groundwater and can be used to develop suitable Sb pollution management strategies.

Shale-derived soils have higher clay, organic matter, and secondary Fe oxide content than other bedrock types, all of which can sequester Hg. However, shales also can be Hg-rich due to their marine formation. The objectives of this study were to determine the concentration and phase partitioning of Hg in seven upland weathering profiles from New York to Tennessee USA and use geochemical normalization techniques to estimate the extent of Hg inheritance from weathering of shale bedrock or sequestration of atmospheric Hg. Total Hg concentrations in unweathered shale ranged from 3 to 94 ng/g. Total Hg concentrations decreased with depth in the Ultisols and Alfisols, with total Hg concentrations ranging from 18 to 265 ng/g. Across all shale soils and rocks, the oxidizable fraction of Hg (15% H2O2 extraction) comprised a large portion of the total Hg at 68% ± 8%. This fraction was dominated by organic matter as confirmed with positive correlations between Hg and %LOI, but could also be impacted by Hg sulfides. Across all sites, the reducible fraction of Hg (citrate-bicarbonate-dithionite extraction) was only 10% ± 4% of the total Hg on average. Thus, secondary Fe oxides did not contain a significant portion of Hg, as commonly observed in tropical soils. Although colder sites had a higher organic matter and sequestered more Hg, τ values for Hg indexed to Ti suggest that atmospheric deposition, such as pollution sources in Ohio River Valley, drove the highest enrichment of Hg along the transect. These results demonstrate that shale-derived soils have a net accumulation and retention of atmospheric Hg, primarily through stabilization by organic matter.

The majority of Critical Zone research has emphasized silicate lithologies, which are typified by relatively slow rates of reactivity and incongruent weathering. However, the relatively simpler weathering of carbonate-dominated lithology can result in secondary mineral deposits, such as speleothems, which provide a long-term archive for Critical Zone processes. In particular, carbon isotopic variability in speleothems has the potential to provide records of changes in vegetation, soil respiration, carbon stabilization in deep soils, and/or chemical weathering in the host rock. Despite this opportunity to reconstruct many Critical Zone processes, multiple influences can also make interpretion of these speleothem carbon isotope records challenging. The integration of observational data and simulations specific to karst systems offers an interpretive framework for these unique time-averaged records accumulated through the evolution of carbonate landscapes. Here, we present a forward and process-based reactive transport simulation based on a multi-year monitoring study of Blue Spring Cave in central Tennessee, USA. The simulations describe the fluid-driven weathering of limestone including explicit tracking of dissolved calcium, stable carbon, and radiocarbon isotope ratios based on reaction rates calibrated through laboratory batch reaction data. We find that calcium concentrations and radiocarbon isotope ratios are strongly influenced by the combination of fluid flow rate and soil CO2 content, and require rapid gas phase communication between the overlying soil boundary condition and interior karst to sustain both elevated limestone weathering rates and relatively modern radiocarbon signatures. Stable carbon isotopes are largely dictated by temperature-dependent equilibrium fractionation among contemporaneous species. These simulations are extended to a wide range of parameter space to demonstrate the environmental factors that these isotope proxies record.

The Krakatau islands complex was formed after the huge eruption of the late Mt. Krakatau in 1883. The complex consists of four islands: Rakata, Panjang, Sertung, and Anak Krakatau. While volcanic activity and plant succession have been extensively studied in the Krakatau area, the soils received less attention. This study characterizes the morphology, chemistry, and geochemistry of the soils from the Krakatau islands. Ten sampling sites were selected from Mt. Anak Krakatau, Rakata, Panjang, and Sebesi islands. The elemental concentration of the samples was measured using the X-ray fluorescence (XRF). In addition, chemical weathering indices were calculated from the geochemical elements. Linear discriminant analysis was used to separate materials from the four islands based on their geochemical concentrations (SiO2, Al2O3, Fe2O3, CaO, MgO, K2O, SO3, P2O5, Ti, and Zr). While the four islands were nearby and influenced by the eruption of Mt. Krakatau, the analysis showed that the geochemical characteristics of volcanic ash for each island are distinct. Mahalanobis distance differentiated soils of Anak Krakatau from the others. Base cations loss in Sebesi was larger than in Rakata, Panjang and Anak Krakatau. Meanwhile, desilication was larger in Rakata compared to Sebesi, Panjang, and Anak Krakatau. The following sequence of weathering degree was determined: Sebesi > Rakata = Panjang > Anak Krakatau. Comparison between sites allowed differentiation of origin of the volcanic materials and a calculation of a relative weathering sequence. This study suggests that the geochemical characteristics of the volcanic materials on these islands are unique and can be used to assess its weathering process and pedogenesis.

In this study, the geochemistry and mineralogy of regoliths formed on Fogo Island (Cape Verde), a polygenic strato-volcano built during the Quaternary, are used to assess the geomorphological factors that control the early stages of basalt weathering. Fogo Island soils are mainly derived from relatively homogenous silica-undersaturated basaltic rocks. However, a discernible exotic component is recognized in areas most exposed to prevailing winds via ratios of non-mobile elements that are hosted in different amounts by basaltic rocks (e.g. Th, Sc and Ti). The weathering extent is evidenced by a relative depletion in mobile elements (e.g. Na, Ca, Mg) and an enrichment in non-mobile elements (e.g. Ti, Fe, Sc, Al), the decomposition of the most labile minerals (olivines) and the formation of secondary components (phyllosilicates and some Fe-oxides, such as hematite-goethite), along with the enrichment in quartz supplied from non-volcanic areas. Weathering depends on bedrock age and type (pyroclastic deposits v. lava-flows). In particular, soils covering older volcanic units tend to be more affected by chemical alteration than those overlying younger units. In addition, more intense weathering is observed in locations characterized by a combination of moderate elevation, slopes with low gradient and relatively high rainfall. The present investigation shows that even in low humidity environments recently formed basalts are affected by weathering, with the extent of chemical decomposition being mainly determined by the age of surface exposure and local orographic/climatic features.

The relevance of the research. In the Tomsk region, the weathering crusts are very widespread, their gold content has been established, but a detailed study of the mineral composition has not previously been carried out. The relevance of the research is caused by the need to identify the conditions for formation of weathering crusts and to establish the patterns of accumulation of a wide range of minerals in them. The main aim of the research is to study the morphological and chemical features, paragenetic associations and distribution of minerals of the phosphate group, division into primary, transformed, and newly formed, the use of phosphates as minerals-indicators of the conditions for the formation of weathering crusts and their relationship with the distribution of gold. The object: residual and redeposited weathering crusts of the Tomsk region and the minerals of the phosphate group contained in them. Methods. The crystal morphological features of minerals of the phosphate group, their paragenetic associations were studied microscopically using an OLYMPUS SZX10 stereomicroscope, the chemical composition of minerals was determined using a HORIBA Scientific XGT-7200 X-ray fluorescence microscope and a TESCAN VEGA 3 SBU X-50 X-50 EDS Max OXFORD scanning electron microscope. Results. In the weathering crusts of the Tomsk region, phosphates of the apatite group, rare earth elements, and aluminophosphates of the crandallite group have been found. Phosphate minerals are divided into groups: primary terrigenous phosphates, stable in weathering crusts and released during the destruction of bedrock (monazite, xenotime, apatite), hypergene-transformed, altered during weathering (monazite), and secondary (monazite, cularite, flitorensite, crandallite, goyacite, gorseixite, plumbogumite). Established in different zones of the weathering crust, phosphate associations for the most part represent links in the successive transformation of minerals from calcium and rare-earth phosphates to aluminum, indicating an increase in the acidity of the mineral formation environment. In the upper part of the hydrolysis zone of the residual weathering crust, the greatest accumulation of gold is noted.

Himalayan glaciers are retreating, and glacial lakes are evolving and proliferating as a result of climate change. Glacier retreat marks in the formation and expansion, and sometimes outburst of moraine-dammed lakes. Lato Lake is one of the high-altitude and unexplored glacial lakes upstream of Gya-Miru village in the Leh-Ladakh region. This study is the first of its kind to assess hydrogeochemistry (HCO3−, SO42−, NO3−, Cl−, F−, Ca2+, Mg2+, Na+, and K+) and studying the dynamics of a moraine-dammed lake in the Ladakh Himalayas. We observed substantial expansion of Lato Lake over the past 50 years between 1969 and 2019, and the areas of the lake have increased while the glacier area is reduced by 16.4% and 4.15%, respectively. The pH values ranging from 7.6 to 8.1 show slightly alkaline. HCO3−, Ca2+, and SO42− were the most dominant ions during the study period 2018–19. The high (Ca2+ + Mg2+) and a low (Na+ + K+) ratio to the total cations show that Lato Lake receives ions from rock weathering, primarily from carbonate rocks. Gibbs and Na-Mixing plot also support the hydrogeochemistry of lake water was primarily controlled by rock weathering. HYSPILT backward trajectory model suggested that atmospheric input mainly originated from the seawater vapor transported by the summer monsoonal and westerly circulation systems. Results show that the lake has a substantial impact on the long-range transport of ocean water relative to local interferences.

The landslide mechanism and failure mode of the gently sloping Piedmont region are analyzed in Fangshan and Zhutoushan hills in the Nanjing area of Jiangsu Province, China. These hills are underlain by volcanic rocks and have a distinctive stratigraphic structure composed of fill or clay at the surface, coarse-grained soil or fully weathered rock in the middle, and highly or moderately weathered rock at the bottom. Landslides occurred during or after heavy rainfall, and the monitored displacements of the slope surface indicated that sliding had not stopped after a long period of continuous rainfall. Through monitoring of groundwater and simulation, we found that the low-permeability highly weathered rock can restrict the activity of the lower aquifer, resulting in a rapid rise of pore pressure and formation of confined water in response to rainfall, which can lead to slope failure. We discuss the mechanism and avulsed–drifted failure mode of the landslides considering seepage deformation and pressure balance. Finally, we propose appropriate control measures for these landslides. The results of this paper will contribute to prevention of similar landslide geological hazards.

The delivery of potentially reactive iron minerals to the marine environment exerts a major control on ocean and marine sediment biogeochemistry, including the preservation and burial of organic carbon. One aspect of the global iron cycle that has received little attention concerns the phase partitioning of iron in highly chemically-weathered sediments from (sub)tropical mountainous regions, where the sediment is commonly deposited directly onto adjacent continental margins. Here, we report the phase partitioning of particulate iron in surface seafloor sediments deposited from oxic bottom waters along the east coast of China, including the Bohai Sea, Yellow Sea and East China Sea, in addition to the continental shelf region adjacent to the (sub)tropical mountainous island of Hainan in the northern South China Sea. We document highly reactive (FeHR) to total iron (FeT) ratios for the Bohai Sea, Yellow Sea and East China Sea that are typical of global marine sediments deposited under oxic water column conditions. By contrast, FeHR/FeT ratios in Hainan offshore sediments are significantly elevated above normal oxic marine sediments. These Hainan offshore sediments display a strong positive correlation between FeHR/FeT ratios and the chemical index of alteration (CIA) weathering proxy, suggesting that the Fe speciation systematics are controlled by the intensity of chemical weathering. This observation is supported by additional geochemical data and Nd isotope analyses, which suggest a common source lithology for all the studied regions. The Hainan sediments thus document a specific scenario, whereby highly chemically weathered sediments from the mountainous Hainan region bypass the inner shore settings that commonly disproportionately trap Fe (oxyhydr)oxide minerals, depositing high concentrations of FeHR on the adjacent continental margin. Such enrichments likely aid in the preservation of organic carbon in marine sediments, suggesting that organic carbon preservation and burial may be enhanced by elevated FeHR in such settings. We also establish a set of essential criteria for potential recognition of chemical weathering-induced enrichments in FeHR/FeT ratios in ancient marine sediments.

The coastal flanks of Mt Etinde is wedged between the sea and the southwestern slope of Mt Cameroon. The only fresh water resources available for multipurpose uses in this area are mountain springs and streams that drain volcanic materials. To access the sources, processes and assess the ecological risk associated with hydrochemicals and heavy metals in these mountain water resources, 18 water samples were collected in different seasons at 4 locations between may 2009 and december 2010 for major ions and heavy metals determination. The sampled waters ranged from neutral to slithly alkaline, weakly mineralized and dominated by Ca–Mg–HCO3 water type irrespective of season. The hydrochemical ratios revealed ions chemistry mostly influenced by geogenic source of silicate rock weathering and atmospheric inputs. Sampled waters had low concentration of heavy metals which are less mobile in the aqueous phase, controlled by hydraulic condition. Geochemical processes of mineral dissolution and reverse ion exchange coupled with hydrodynamic processes of flushing at the weathering front and soil leaching are the main controls on the water chemistry in the area. Despite agricultural and other anthropogenic activities, quality indices in the study area indicate the absence of anthropogenic inputs. Key words: Major ions, heavy metals, rocks weathering, soil leaching, water quality assessment.

Earth’s plate-tectonic activity regulates the carbon cycle and, hence, climate, via volcanic outgassing and silicate-rock weathering. Mountain building, arc–continent collisions and clustering of continents in the tropics have all been invoked as controlling the weathering flux, with arcs also acting as a major contributor of carbon dioxide to the atmosphere. However, these processes have largely been considered in isolation when in reality they are all tightly coupled. To properly account for interactions among these processes, and the inherent multi-million-year time lags at play in the Earth system, we need to characterize their complex interdependencies. Here we analyse these interdependencies over the past 400 million years using a Bayesian network to identify primary relationships, time lags and drivers of the global chemical weathering signal. We find that the length of continental volcanic arcs—the fastest-eroding surface features on Earth—exerts the strongest control on global chemical weathering fluxes. We propose that the rapid drawdown of carbon dioxide tied to arc weathering stabilizes surface temperatures over geological time, contrary to the widely held view that this stability is achieved mainly by a delicate balance between weathering of the seafloor and the continental interiors. Earth’s surface temperature is stabilized by the drawdown of CO2 owing to weathering of continental arcs, whose length is shown to be a primary control on global weathering fluxes, according to a probabilistic analysis of interdependencies.

In alpine environments, tectonic processes, past glaciation and weathering processes fracture rock and prepare or trigger rockfalls, which are important processes of rock slope evolution and natural hazards. In this study, I quantify thermally and ice-induced rock and fracture kinematics and place these in the context of their role in producing rockfall and climate change. I conducted laboratory measurements on intact rock samples and installed temperature loggers and crackmeters at four rockwalls reaching from 2585 to 2935 m in elevation in the Hungerli Valley, Swiss Alps. My laboratory data show that thermal expansion followed three phases of rock kinematics, which resulted in a hysteresis effect. In the field, control crackmeters on intact rock reflected these temperature phases, and based on thermal expansion coefficients of these observed phases, I modelled thermal stress. Model results show that thermal stress magnitudes were predominantly below rock strengths. Crackmeters across fractures revealed fracture opening during cooling and reverse closing behaviour during warming on daily timescales. Elevation-dependent snow cover controlled the number of daily temperature changes and thermal stresses affecting both intact and fractured rock, while the magnitude is controlled by topographic factors influencing insolation. On a seasonal scale, slow ice-segregation-induced fracture opening can occur within lithology-dependent temperature regimes called frost cracking windows. Shear plane dipping controlled whether fractures opened or closed irreversibly with time due to thermally induced block crawling on an annual scale. Climate change will shorten snow duration and increase temperature extremes and will, therefore, affect the number and the magnitude of thermal changes and associated stresses. Earlier snowmelt in combination with temperature increase will shift the ice-induced kinematic processes to higher elevations. In conclusion, climate change will affect and change rock and fracture kinematics and, therefore, change rockfall patterns in alpine environments. Future work should quantify rockfall patterns and link these patterns to climatic drivers.

Hot and humid subtropical plateau regions are susceptible to land degradation in the form of weathering and gully erosion. Here, we investigate chemical weathering, gully erosion and cohesiveness through field-based measurements with a view to understand the controlling factors of potential land degradation, in complex river basin of the Chotanagpur plateau region in Eastern India. The layers of controlling factors of gully erosion were developed and prioritized considering boosted regression tree (BRT), alternative decision tree (ADT), particle swarm optimization (PSO) and random forest (RF) algorithms in the R software, and the results of these methods were also validated using receiver operating characteristic (ROC) curves. The spectroscopic analysis was carried out of collected soil samples to measure the degree of chemical weathering and cohesiveness. Furthermore, the climatic elements like temperature and rainfall were also considered for estimating the chemical weathering. The results of the gully erosion models (i.e., BRT, ADT, PSO and RF) show remarkable accuracy with ROC values of 0.93, 0.89, 0.91 and 0.84, respectively. An advanced decision tree model was integrated with the results of degree of chemical weathering and cohesiveness in geographical information system platform. The land degradation map developed from this approach shows that 10.53% of the study area is highly affected, whereas 17.36% area is moderately affected and the rest of the 73.85% area is less affected by land degradation. Our results provide essential information for policy makers in adopting measures for minimizing and controlling the land degradation. Our novel approach is significant to assess land degradation to a large scale.

The abundance and distribution of dissolved Re (DRe) were determined in the freshwater part of the Krka River (Croatia), which drains a karst landscape, and in the salinity gradient of its highly stratified estuary. Due to the low DRe concentration, a batch procedure consisting of a pre-concentration step using an anion exchange resin (Dowex) and analysis of DRe in 8 M HNO3 eluate using high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) was applied. Due to potentially inconsistent recoveries, which ranged from 60 to 87%, quantification was performed using the isotope dilution technique (ID). DRe concentrations in the Krka River increased downstream, from 6.2 pM at the spring site to 11.9 pM upstream of the estuary region. Weathering of the surrounding carbonate lithology is assumed to be the source of the natural Re. Two specific anomalies were registered: a strong increase in DRe concentration due to anthropogenic input near the town of Knin (27.5 pM) and a decrease at a downstream site caused by subsurface input of freshwater from the Zrmanja River, resulting in a relatively low DRe concentration (8.5 pM). In the estuarine region, a near- conservative behavior of DRe was found in the salinity gradient of the upper surface layer, with DRe concentrations ranging from 18 to 38 pM. Anthropogenic input was suspected within the estuarine segment near the urban area, causing a small positive deviation from the conservative line. In the bottom seawater layer, a minor decrease in DRe concentration in the most upstream estuarine regions was apparent, implying weak scavenging of Re

”Rock moisture” (exchangeable water stored in weathered bedrock beneath the soil) is a key and yet overlooked component in hydrologic cycles. It can be partitioned to free water and capillary-bound water. Determining dynamic partitioning of rock moisture is crucial for conceptualizing critical zone functions and climate and hydrologic modeling. However, the quantification of rock moisture partitioning is challenging, especially in rocks with complex pore structures and weathering patterns. Laboratory nuclear magnetic resonance (NMR) measurements are performed on heterogeneous bedrock samples from a merokarst vadose zone to quantify the dynamics of rock moisture partitioning during the drying process. By fitting a multi-Gaussian function, NMR [Formula: see text] distributions are autodecomposed into multiple [Formula: see text] peaks representing different pore sizes and environments. This spectral analysis enables us to track the change of position, width, and area of peaks at any given saturation stage, shedding light on water depletion rates and patterns, water residence time, and partitioning and redistribution of the water in drying rocks. The changes in [Formula: see text] peaks associated with drying among our samples show strong correspondence with mineralogy, and [Formula: see text]-[Formula: see text] measurements indicate that rock moisture depletion and redistribution are closely related to the pore structures. Limestone with well-connected macropores shows a sequential water loss from large to small pores, whereas limestone with poorly connected macropores simultaneously loses water from all pore sizes. The [Formula: see text] peak decomposition analysis can be extended to the field scale to track rock moisture partitioning in the pore network. This capability has implications for documenting critical zone processes, including quantifying water storage dynamics, estimating plant available water, and monitoring weathering processes.

Unconventional volcanic reservoir is different from conventional reservoir in reservoir space, diagenesis, pore formation and evolution. The Carboniferous volcanic reservoir was selected in Junggar Basin, Northwest China because based on sediment/rock cores and outcrop data, diagenesis and pore evolution were studied by elemental measurements, thin section observations, and diagenetic analyses. These analyses shows that the reservoir lithology is predominantly intermediate-basic volcanic, and the reservoir storage space is composed mainly of secondary dissolved pores and fractures. The reservoir displays great heterogeneity, and has experienced a great variety of diagenetic alteration during various diagenetic stages including: (1) eruption fragmentation, crystallization differentiation and condensing consolidation at consolidated diagenetic stage; (2) metasomatic alteration, filling, weathering and leaching, dissolution by formation fluids and tectonism at the epigenetic modifications stage. The formation and evolutionary process of the pores is extremely complicated. The primary pores were formed during the consolidated diagenetic stage, and laid a foundation for the late development and alteration of effective reservoir. During the epigenetic modifications stage secondary reservoir storage space was developed via the formation of secondary pores and the development of fractures through weathering and leaching, dissolution by formation fluids and tectonism.

The detachment of rock fragments from fractured bedrock on hillslopes creates sediment with an initial size distribution that sets the upper limits on particle size for all subsequent stages in the evolution of sediment in landscapes. We hypothesize that the initial size distribution should depend on the size distribution of latent sediment (i.e., fracture-bound blocks in unweathered bedrock) and weathering of blocks both before and during detachment (e.g., disintegration along crystal grain boundaries). However, the initial size distribution is difficult to measure because the interface across which sediment is produced is often shielded from view by overlying soil. Here we overcome this limitation by comparing fracture spacings measured from exposed bedrock on cliff faces with particle size distributions in adjacent talus deposits at 15 talus–cliff pairs spanning a wide range of climates and lithologies in California. Median fracture spacing and particle size vary by more than 10-fold and correlate strongly with lithology. Fracture spacing and talus size distributions are also closely correlated in central tendency, spread, and shape, with b-axis diameters showing the closest correspondence with fracture spacing at most sites. This suggests that weathering has not modified latent sediment either before or during detachment from the cliff face. In addition, talus at our sites has not undergone much weathering after deposition and is slightly coarser than the latent sizes because it contains unexploited fractures inherited from bedrock. We introduce a new conceptual framework for understanding the relative importance of latent size and weathering in setting initial sediment size distributions in mountain landscapes. In this framework, hillslopes exist on a spectrum defined by the ratio of two characteristic timescales: the residence time in saprolite and weathered bedrock and the time required to detach a particle of a characteristic size. At one end of the spectrum, where weathering residence times are negligible, the latent size distribution can be used to predict the initial size distribution. At the other end of the spectrum, where weathering residence times are long, the latent size distribution can be erased by weathering in the critical zone.

National Highway (NH) 29 is a strategic highway of India that runs from Assam to Manipur, through Nagaland. This highway, also known as the Asian Highway 1 (AH 1), connects India to the Southeast Asian countries via Myanmar. A section of the highway, located near the capital city of Kohima, was damaged by major landslides on 1st August 2018. Another landslide occurred in the same area on 4th August 2019, which totally blocked vehicular movement for nearly a month. In both instances, the area received heavy rainfall intermittently for some days preceding slope failure. Geologically, the area is made up of highly jointed and fractured Disang rocks that are composed predominantly of shales intercalated with minor beds of siltstone, and some clay pockets indicating weathering of these rocks. The slide material comprises a mixture of loose debris of shales and saturated clays. A multi-parameter study involving geotechnical, kinematic and joint analyses, slope mass rating, resistivity surveys, and remote sensing using an Unmanned Aerial Vehicle (UAV) was carried out to determine the factors responsible for the two landslide events in this area. The study finds that the soils, with low values of unconfined compressive strength, are one of the major contributors to slope failure in the area. Slope stability analyses demarcate the slopes of the study area as partially stable to highly unstable. Kinematic and joint analyses indicate that the rocks are structurally weak due to the presence of joints, which make them susceptible to wedge failure. Analyses of joints and slickensides confirm complex deformation taking place in the area. The study of satellite imagery of the study area, coupled with field evidences, indicate that the area is crossed with faults. The presence of one such fault and two confined aquifers was validated by resistivity surveys, which explains the shearing of the rocks and high degree of weathering of the country rocks. The low shear strength of the soils and saturation of other slope materials due to heavy rainfall led to the two landslides events.

The Yarlung Zangbo River Basin (YZRB) is situated in the southern part of the Tibetan Plateau and remains in a mostly natural state. To understand the chemical characteristics of spring water and its controlling factors in the YZRB, 68 sets of spring water samples were analyzed using hydrochemical and isotopic techniques. The spring water was found to be slightly alkaline with total dissolved solids (TDS) below 1000 mg L−1. Major ions were Mg2+, Ca2+, SO42−, and HCO3−. The spring water types in this basin were determined to be HCO3-Ca·Mg and SO4·Cl-Ca·Mg. Ion exchange and dissolution of carbonate, gypsum, and silicate were identified as the prevalent hydrogeochemical processes contributing and defining spring water chemistry in this basin. Saturation indices (SI) of most major minerals studied in this region were below zero, indicating that these minerals remain under-saturated in the spring water in this area. Overall, the rank of different processes in terms of their contribution to the chemical composition of spring water in the YZRB was carbonate weathering > evaporate dissolution > silicate weathering > precipitation input. The content of 18O in spring water ranged from −22.22‰ to −14.08‰ with a mean of −18.15‰. Samples collected below and close to the local and global meteoric water lines indicated that spring water in this area is derived from meteoric water with chemistry affected by evaporation.

This work presents the complex nature of weathered geomaterials by investigating the influences of geological features (textural, mineralogical, in situ specific volume, strength, structure) of parent rocks on weathering of decomposed volcanic rocks in the reconstituted and intact states. This was done by vertically comparing samples of the same weathering degrees but belonging to different formations and horizontally by comparing samples of different weathering degrees that belong to different formations. This is very important due to complex nature of geology and weathering processes of volcanic rocks. This was achieved through comprehensive physical and index tests, microstructure and mineralogical analyses, oedometer and triaxial tests as well as analyses of previous studies. Geological characters of parent rocks have been found to affect grading and index properties, mineralogy, compressibility, in-situ behaviour and strength. However, fabrics of decomposed volcanics are not parent geological features dependent and parent geological characters do not influence the effects of structure using both stress sensitivity and normalisation for volume. Based on these, geological and geotechnical properties of samples from different formations could be characterised separately to obtain parameters needed for engineering design and constructions. However, two geological units can be combined into the same geotechnical unit because physical, textural and mineralogical features lead to similar mechanical behaviour.

Dense networks of dilated fractures occur locally in the upper 5–15 m of bedrock in basement gneisses in eastern Sweden. Near Forsmark, pre-existing sub-horizontal fractures have been jacked open and filled with water-lain sediment, likely during the latest Weichselian glaciation. Despite extensive previous research, it is uncertain whether subglacial hydraulic jacking led to the generation of new fractures, in addition to reactivation of pre-existing ones. Re-analysis of historic photos from excavations near the Forsmark power plant indicates formation of two types of new fracture. Firstly, rock fragments were broken off the main fracture surfaces as existing fractures were jacked open. Secondly, fracture analysis shows that whilst few subvertical fractures occur above tight sub-horizontal fractures, a higher density of vertical fractures occurs above dilated sub-horizontal fractures, suggesting new formation. We apply a model of beam failure theory, borrowed from structural engineering, to constrain potential new fracture generation, using assumptions based on measured water pressure fluctuations from beneath the Greenland Ice Sheet. This modelling shows that beam failure is a plausible mechanism for the generation of new vertical fractures during a subglacial water fluctuation cycle under a range of realistic glaciological conditions. This implies that hydraulic jacking can result in further in situ disruption and brecciation of the shallow rock mass, decreasing the rock mass strength and increasing its hydraulic conductivity. Altogether, hydraulic jacking of existing fractures and the formation of new vertical fractures results in effective subglacial mechanical weathering of the shallow rock mass.

The Vanj River is one of the tributaries of the transboundary Panj River between Tajikistan and Afghanistan which, in turn, is considered to be one of the full-flowing tributaries of Amu Darya, the largest river in Central Asia. The Amu Darya River is the main source of water supply for the wide agricultural lands of Turkmenistan and Uzbekistan. Moreover, it is a source of drinking water supply in most localities and villages. Therefore, monitoring the ecological state and chemical composition of the Amu Darya River and its tributaries is an urgent problem. Apparently, a significant role in the formation of the chemical composition of the water of the principal river belongs to its tributaries and, because the catchment area of almost all the tributaries of the Panj River is located in the highlands of Pamir, where the processes of rock weathering develop under the conditions of climate change, the study of the effect of the weathering products on the chemical composition of rivers is an important task in terms of timely detection of heavy metals and radionuclides and their subsequent neutralization. The aim of the research is to determine the origin of the chemical composition of the water and presence of stationary sources of pollution of the Vanj River. It is found that there are no sources of anthropogenic pollution at the upper reaches of the Panj River and basin of the Vanj River, and the formation of the chemical composition of the Vanj River occurs as a result of the weathering of the basin rocks. The dependences between the chemical elements of the Vanj and Panj rivers are found by applying the Pearson correlation. It is found by the determination of the mutual ratios of alkaline earth and alkaline elements with Cl– and $${\text{SO}}_{4}^{{2 - }}$$ anions that the chemical composition of the Vanj River is mainly determined by the weathering of silicate rocks. The components enriched by the Vanj River, the main tributary of the Panj River, are found by the difference in the concentrations of the chemical elements of the Vanj and Panj rivers.

Numerous lakes in western China are excellent sites for understanding environmental change. However, what dominates rare earth element (REE) variations are still under debate in the lake environmental research. In this study, we selected 28 surface sediment samples from 17 lakes (i.e. large-scale lakes, small water bodies, etc.) in the Qinghai-Tibet Plateau and Xinjiang area. These samples were analyzed to reveal the behavior of the REEs and major elements. These REE patterns are characterized by light rare earth element (LREE) enrichment, weak Ce anomaly (0.84–0.98, 0.94 on average) and negative Eu anomaly (0.53–1.00, 0.67 on average). The homogeneous REE patterns may reflect similar REE of the source lithologys. However, the REE abundances showed some significant differences. In this study, water chemistry data analyses inferred that the highly REE values appear possibly in the saltwater lake, and also related to carbonate mineral, whereas pH played a minor role in REE concentrations. In large-scale lakes (e.g. Lake Bosten and Lake Ulungur), the results showed that the relatively larger REE values are in the margins of lakes. Moreover, lower REE contents are towards the central region. Comprehensive study suggested that five major factors control the REE contents: (1) The REE tends to increase with the increase of the weathering intensity. (2) Likewise, heavy mineral (i.e. rutile, anatase, zircon, etc.) are probably primary in these sediments because they are highly enriched in the REE. (3) The contribution of Fe-Mn oxides is significant in sediments because their concentrations highly correlate with the REE. (4) The carbonate mineral (mainly calcite) played a significant role on the REE values in the lakes because the REEs are incorporated into the carbonate minerals generating the low REE concentrations. (5) Major element analysis, mineral analysis, and grain-size data analysis showed that the REE distribution is chiefly influenced by finer grain-size component of lake sediments due to the decreasing proportion of quartz and feldspar than coarser one. Moreover, the clay minerals in finer grain-size sediments can highly absorb the REE.

O município de Goiana está localizado no extremo norte do litoral pernambucano limitando-se diretamente com o estado da Paraíba. Está situado ao norte da capital pernambucana (Recife) e inserido no contexto geológico da Bacia Paraíba onde predominam coberturas sedimentares desde o Cretáceo Superior até o recente. A Formação Barreiras abrange consideravelmente uma porção territorial do município. Esta unidade está relacionada a existência de leques aluviais e sistemas fluviais que possivelmente gradavam para sistemas deltaicos e, apresentam uma variação faciológica desde argilitos até conglomerados. A ação do intemperismo e da lixiviação associada sobre as camadas areno-argilosas dessa unidade originou a ocorrência de depósitos arenosos com alto teor de SiO2 (> 95%) conhecidos como “areias brancas”. A espessura destes depósitos varia entre 0,1 e 3 metros e os grãos são bem selecionados e subangulosos. A fração granulométrica predominante é fina a média de acordo com os padrões da Associação Brasileira de Normas Técnicas (ABNT). Considerando todos as características do bem mineral, a qualidade e a composição dos depósitos, as “areias brancas” são consideradas de boa qualidade para a indústria de construção, razão pela qual os estudos e as explorações vêm se intensificando na região.

International audience; The Oligocene-Miocene boundary Asian climatic reorganization linked to the northward migration of the East Asian monsoon into subtropical China is a potentially important but poorly constrained atmospheric CO2 consumption process. Here, we performed a first-order estimate of the CO2 consumption induced by silicate chemical weathering and organic carbon burial in subtropical China related to this climatic reorganization. Our results show that an increase in long-term CO2 consumption by silicate weathering varies from 0.06×1012 to 0.87×1012 mol yr−1 depending on erosion flux reconstructions, with an ~50% contribution of Mg-silicate weathering since the late Oligocene. The organic carbon burial flux is approximately 25% of the contemporary CO2 consumption by silicate weathering. The results highlight the significant role of weathering of the Mg-rich upper continental crust in East China, which would contribute to the rapid decline in atmospheric CO2 during the late Oligocene and the Neogene rise in the seawater Mg content. If this climatic reorganization was mainly induced by the Tibetan Plateau uplift, our study suggests that the growth of the Himalayan-Tibetan Plateau can lead to indirect modification of the global carbon and magnesium cycles by changing the regional hydrological cycle in areas of East Asia that are tectonically less active.

The red beds in Zhejiang province of China host the highest concentration of Danxia arched rock shelters in the world, just as the Colorado Plateau in the western USA hosts the world’s largest concentration of natural arches and bridges. This study investigated the geological background of the arched rock shelters and compared them to the natural arches and bridges, based on field study and a literature review. It was found that Zhejiang arched rock shelters differ from Colorado Plateau natural arches and bridges in geometry and formation mechanism. Statistical geometric data on arch geometry shows that Danxia arched rock shelters in Zhejiang tend to be relatively flat. They are relatively low features with long spans, and great depth. The natural arches and bridges on the Colorado Plateau are similar to each other, but the bridges are larger than the arches. The geometric differences between the arched landforms could be attributed to their different geologic history and to their different formation mechanisms. The arched rock shelters in Zhejiang are formed by differential weathering between sandstone and conglomerate due to moisture-induced tensile stresses. In contrast, natural arches on the Colorado Plateau are closely related to the Salt Valley anticline, vertical tectonic fractures, and horizontal discontinuities in rock fins. The Colorado Plateau natural bridges were formed by river erosion.

Correlating morphological surfaces, such as terraces and alluvial fans, is necessary in geomorphology researches. Gravel characteristics have been analysed to estimate the weathering degree. However, the composition of gravels was complicated and a feasible quantitative method is still need. Therefore, the objective of this study was to investigate the weathering process of an alluvial fan in western Sichuan Basin and find a practical method in correlating morphological surfaces. The Qingyi River frequently migrated since 500 ka ago and generated several paleo alluvial fans, one of which is the Dansi alluvial fan. Major and trace element samples form an uninterrupted outcrop of the Dansi fan were tested to estimate the weathering process of a single fluvial profile. Results showed that the weathering index decreased regularly with depth, meaning that the surficial sample could represent the weathering degree of the morphological surface. In addition, the sand fillings between the gravels in the river sediments were sensitive to the weathering process and were able to reflect quantitative weathering degree. Therefore, we suggested that the weathering index of the sediments closed to the surface can represent the weathering degree of morphological surfaces.

The weathering process occurs on the Earth's surface, especially in tropical climates, and causes the parent rock's mobilization of elements. Weathering is interesting because it is often associated with the enrichment of economic materials such as iron, alumina, and REEs. The weathering profile of Tertiary volcanic rocks is spread across tropical Sumatra. This study aims to describe REEs' kaolinization and mobilization process on the weathering profile of volcanic rocks in the east of Mandeh Peak, West Sumatra. XRF and ICP-MS devices are utilized to measure the abundance of major oxides, trace elements, and REEs. The increase in IOL is proven to occur in the same direction as weathering levels. A triangular diagram of SiO2-Al2O3-Fe2O3T indicates kaolinization on weathering at Mandeh Peak. Feldspar and mica were prone to weathering and instantly turn into kaolinite in the early stages of weathering to explain the main oxide variations in weathering profiles. The weathering process has increased the amount of alumina and iron significantly relative to the parent rock. There is no REEs enrichment on any of the weathering horizons other than its composition on the parent rocks. Part of Ce is oxidized into Ce4+ and left on the saprolite horizon. This condition makes Ce's mobility in the direction of weathering level is different from other REEs.

The relevance of groundwater hydrogeochemistry to explain the occurrence and distribution of arsenic in groundwater is of great interest. The insightful discussions on the control of shallow groundwater (

The Cryogenian Period (717–635 Ma), or ‘Snowball Earth’, was an unusually cool period of Earth history when glaciers extended to low latitudes. Past ideas on causes of this widespread glaciation in...

Magnetic susceptibility (MS) as a fast, non-destructive, and reasonable technique is very useful in soil genesis and evolution studies. The MS of soils along a climolithotoposequence in Jazmoorian Watershed was studied in the present research and the vertical distribution of MS in the representative pedons affected by soil forming factors (parent material, climate and relief) was also investigated. Rock pediment, mantled pediment, piedmont plain, alluvial fan, and playa geomorphic positions with two igneous (gabbro, diorite, granite, and andesite) and sedimentary (limestone, conglomerate and playa deposits) parent materials were selected. Thirteen representative pedons which best reflected the variations of soil forming factors were studied. Results of the study showed that the maximum (877.8 × 10−8 m3 kg−1) and the minimum (5.2 × 10−8 m3 kg−1) low frequency (χlf) MS were respectively determined in the soils formed on igneous and sedimentary parent materials. The χlf values were increased with depth in soils affected by igneous parent material, but the opposite trend was found in soils with a sedimentary origin. The activity ratio of Feo/Fed in xeric and aridic moisture regimes were 0.03 and 0.09, respectively. Meanwhile, MS value in surface soil of pedon 2 (with xeric moisture regime) is lower than its parent material which is a support for the higher weathering of this soil due to higher moisture compared to pedon 5 with an aridic moisture regime. Decreasing evolution trend of soils on igneous parent material was in the order of alluvial fan < piedmont plain < mantled pediment, but in the soils on sedimentary parent material was in the order of playa < rock pediment < mantled pediment < alluvial fan. Results of the study clearly showed that the soil χlf values changed with variations in climate, parent material, and topography.

We report detailed chemical and isotopic data from a subglacial siliceous deposit on andesitic bedrock recently exposed by glacier retreat. Whereas a single

The riparian zone is a river-land ecotone, and its environmental conditions have a significant effect on the river ecosystem and population health. In this study, As, Cu, Cr, Cd, Mn, Fe, Ni, Pb, and Zn in the topsoils of urban riparian zones in a subtropical city in southeast China were quantitatively estimated by inductively coupled plasma-optical emission spectrometry. The geoaccumulation index and health risk evaluation model were adopted to assess the accumulation characteristic and health risk of residents' exposure to metals. Principle component analysis was used to determine the source of metals. The results showed that the mean contents of metals (except Fe) were higher than the soil background value, but none of the metal contents exceeded the mass limit of environmental quality standards. The order of the geoaccumulation index was Cd > Mn > Cu > Cr > Pb > Zn > As > Ni > Fe. The contamination level of Cd was classified as slight, whereas the other metals did not contribute to pollution. The spatial distribution of metals in the riparian zone was compatible with the pattern of functional zones in the adjacent urban areas, where levels of Cr, Cd, Fe, Mn, and Ni were higher in commercial areas, as were Pb and Zn in under-construction land and As in residential and industrial areas. Carcinogenic risks of Cr, As, and Pb were acceptable. The hazard index indicated no significant noncarcinogenic risks from any metals. However, noncarcinogenic risks of metals other than Mn were higher for children than for adults, and the primary exposure route of metal into the human body was ingestion for children and inhalation for adults. Principle component analysis indicated that the primary sources of Cr, Ni, Mn, Cu, and Fe were pedogenic processes and mineral weathering, whereas Zn, As, Pb, and Cd mainly originated from anthropogenic sources, specifically, Zn from transportation emission, Pb from transportation emission and industry waste, As from coal combustion and residential waste, and Cd from pigments/paint used in commercial buildings, urban greening, consumer waste, and transportation emission.