Weathering Rates Research Articles

Effects of biomass co-pyrolysis and herbaceous plant colonization on the transformation of tailings into soil like substrate

Enhancing soil organic matter characteristics, ameliorating physical structure, mitigating heavy metal toxicity, and hastening mineral weathering processes are crucial approaches to accomplish the transition of tailings substrate to a soil-like substrate. The incorporation of biomass co-pyrolysis and plant colonization has been established to be a significant factor in soil substrate formation and soil pollutant remediation. Despite this, there is presently an absence of research efforts aimed at synergistically utilizing these two technologies to expedite the process of mining tailings soil substrate formation. The current study aimed to investigate the underlying mechanism of geochemical changes and rapid mineral weathering during the process of transforming tailings substrate into a soil-like substrate, under the combined effects of biomass co-smoldering pyrolysis and plant colonization. The findings of this study suggest that the incorporation of smoldering pyrolysis and plant colonization induces a high-temperature effect and biological effects, which enhance the physical and chemical properties of tailings, while simultaneously accelerating the rate of mineral weathering. Notable improvements include the amelioration of extreme pH levels, nutrient enrichment, the formation of aggregates, and an increase in enzyme activity, all of which collectively demonstrate the successful attainment of tailings substrate reconstruction. Evidence of the accelerated weathering was verified by phase and surface morphology analysis using X-ray diffraction and scanning electron microscopy. Discovered corrosion and fragmentation on the surface of minerals. The weathering resulted in corrosion and fragmentation of the surface of the treated mineral. This study confirms that co-smoldering pyrolysis of biomass, combined with plant colonization, can effectively promote the transformation of tailings into soil-like substrates. This method has can effectively address the key challenges that have previously hindered sustainable development of the mining industry and provides a novel approach for ecological restoration of tailings deposits.

Carbon Capture and Storage: From Global Cycles to Global Solutions

Anthropogenic carbon emissions have overwhelmed the natural carbon cycle, leading to a dramatic increase in atmospheric CO2 concentration. The rate of this increase may be unprecedented in Earth’s history and is leading to a substantial increase in global temperatures, ocean acidification, sea level rise and potentially human health challenges. In this Geochemical Perspectives we review the natural carbon cycle and its link to global climate. Notably, as directly observed by field observations summarised in this volume, there is a natural negative feedback loop between increasing global temperature, continental weathering rates, and CO2 that has tended to limit Earth climate changes over geological time scales. Due to the rapid increase in atmospheric carbon concentrations, global average temperatures have increased by more than 1.2 °C since the start of the industrial revolution. One way to slow or even arrest this increasing global average temperature is through Carbon Capture and Storage (CCS). Carbon dioxide can be captured either from large industrial point sources or directly from the atmosphere. Taking account of the natural carbon cycle, the most secure approach to storing captured CO2 is by reacting it with mafic or ultramafic rocks to form stable carbonate minerals, a process referred to as “mineral carbonation”. Although mineral carbonation can occur and be accelerated at the Earth’s surface, due to the required scale and required time frames it is most effective in the subsurface. This subsurface mineralisation approach was developed into an industrial scale process through an academic-industrial collaboration called CarbFix. The history of CarbFix, from its beginnings as a concept through its installation as an industrial process is presented in detail. This Geochemical Perspectives concludes with an assessment of the future of subsurface mineralisation as a means to help address the global warming challenge, as well as a detailed list of potential research directions that need to be addressed to further upscale and optimise this carbon storage approach.

The development of laterite weathering profiles as a function of rainfall and time: A geophysical approach

AbstractLaterite weathering profile (LWP) thicknesses are functions of precipitation rate and time, but their exact dependence on them is uncertain. We investigate LWP development on ground surfaces in Hawai'i that are neither aggrading nor eroding across substrates from 0.01 to 4 Ma and rainfall rates of <250 to >3000 mm/a. The Hawaiian Islands provide an excellent opportunity for LWP studies across climates and over millions of years on a single rock type, basalt. LWP weathering rates are usually determined by geochemical approaches. We present a geophysical method once bedrock ages and precipitation rates are known. We employed multichannel analysis of surface waves and horizontal‐to‐vertical spectral ratio methods. Results indicate that >70% of the variability in LWP thickness is due to precipitation and bedrock age. The remainder is attributed to measurement uncertainty and heterogeneity in the permeability of basalt. LWPs develop by two paths. Dry (<1000 mm/a) areas have a negative water balance with evapotranspiration exceeding rainfall. LWPs thicken until they reach a steady state where the storage capacity of the saprolite precludes the percolation of water into subjacent lava. In wetter areas, downslope interflow produces thick laterite wedges near coastlines that migrate upslope over ~1 Ma. Subsequently, they thicken and reach a steady state where precipitation cannot deliver water through the vadose zone. LWPs' thickness (T) increases as a function of time (t) and precipitation (P) according to the expression (95% confidence): . The first partial derivative, or weathering rate, is . Weathering rates decrease with time and are strong functions of t and P. These expressions add considerable insight into the rates and processes driving weathering at large scales and can also be solved for t, giving a rough estimate of the time of landscape formation of eroded surfaces.

Pollution Characteristics and Sources of Heavy Metals in Soil of a Typical Pyrite Concentrated Mining Area in Anhui Province

To identify the characteristics and sources of heavy metal pollution in the surrounding soil of a typical pyrite concentrated mining area in Anhui Province, the pH value and the concentrations of Zn, Cu, Cd, Pb, Cr, Ni, Hg, and As in 42 surface soil samples and 16 soil samples from two vertical sections in the study area were collected and measured. The distribution characteristics, pollution assessment, and source analysis of heavy metal elements were conducted using the ArcGis inverse distance weight interpolation method, Nemero comprehensive index method, principal component analysis method, and absolute factor score-multiple linear regression (APCS-MLR) receptor model. The results showed that the average concentration of the eight heavy metals was 1.03-13.14 times the background value in the Tongling area. The local enrichment of Zn, Cu, Cd, Pb, Hg, and As was obvious, and the spatial distribution was basically consistent with the location of man-made mining activities. The single-factor pollution index evaluation showed that Zn, Cu, Cd, Pb, and As had different degrees of pollution risk, and the pollution degree of Cd and Cu was the most serious, accounting for 47.62% and 42.86% of moderate pollution, respectively. The Nemerow comprehensive pollution index evaluation showed that 61.90% of the soil samples in the study area were moderately polluted. The ground accumulation index evaluation showed that the pollution degree of Zn, Cu, Cd, Pb, Hg, and As in the study area was mainly from light pollution to strong pollution. In the vertical soil profile variation, heavy metals were easily enriched in the surface layer of the soil but migrated slowly to the deep layer, with concentrations mainly above 1 m. The results of source analysis showed that the high geological background and mining contribution rates of Zn, Pb, and As were 37.82%, 43.49%, and 46.63%, respectively. The natural contribution rates of weathering of parent material were 34.02%, 40.88%, and 38.52%, respectively. The sources of Cr and Ni were mainly natural sources of weathering of the parent material, with contribution rates of 91.95% and 73.68%, respectively. Geological high background and mining activities contributed 41.91% of the Cu sources, and atmospheric sedimentation and agricultural comprehensive sources contributed 41.30%. There were many sources of Hg. The natural source of weathering of soil parent material contributed 35.60%, geological high background and mining activities contributed 29.87%, and unknown sources contributed 34.05%. The main source of Cd was atmospheric sedimentation and agricultural comprehensive sources, contributing 81.81%.

What controls the hydrochemical compositions of mountainous river water in a glacierized catchment?

AbstractChemical weathering processes has become a growing issue in research on carbon cycling, however, mineral weathering by sulfuric acid and carbonic acid and its possible impacts on carbon cycle are yet unknown over the typical glacial catchment. To investigate the mechanisms of mineral weathering processes and its influence, the spatial–temporal variations of the major ions in Mingyong River, a glacier‐originated river located on the southeastern edge of the Qinghai‐Tibetan Plateau, were investigated. The seasonal and spatial variations in river solutes were resulted from the hydrological conditions and different mineral weathering rates. The results showed that the major ion compositions of the river waters were characterized by the dominance of Ca2+, Mg2+, HCO3−, with a significantly rich in SO42−. A systematic increase in ionic concentrations (apart from NH4+ and NO3−) was observed in the river water from non‐monsoon to monsoon season as well as from upstream to downstream. Piper diagram results showed 100% (upstream‐midstream) and 72.5% (downstream) contributions to Ca‐HCO3 type, respectively, indicating that a dominated carbonate weathering to the river chemistry. The (Ca2++Mg2+)/HCO3− against (SO42−/HCO3−) scatter suggested that sulfuric and carbonic acid are responsible for chemical weathering. An increased contributions of sulfuric acid from upstream (43%) to downstream (87.3%) on the (Ca2++Mg2+) and from upstream (29.6%) to downstream (88.3%) on HCO3− using the stoichiometry analysis during the monsoon season. Contrarily, H2SO4‐related dissolution (>65%) processes controlled the carbonate weathering during the non‐monsoon season, which indicated that sulfuric acid played a significant part in the process of rock dissolution that intensifies weathering. The effects of accelerated weathering on drinking and irrigation suitability suggested that the Mingyong River water is subject to a salinity hazard. This research demonstrates that the weathering of catchments involving sulfuric acid has the potential to alter carbon cycle and should be considered in global carbon cycle models.

Long‐Term Changes in Concentration and Yield of Riverine Dissolved Silicon From the Poles to the Tropics

AbstractRiverine exports of silicon (Si) influence global carbon cycling through the growth of marine diatoms, which account for ∼25% of global primary production. Climate change will likely alter river Si exports in biome‐specific ways due to interacting shifts in chemical weathering rates, hydrologic connectivity, and metabolic processes in aquatic and terrestrial systems. Nonetheless, factors driving long‐term changes in Si exports remain unexplored at local, regional, and global scales. We evaluated how concentrations and yields of dissolved Si (DSi) changed over the last several decades of rapid climate warming using long‐term data sets from 60 rivers and streams spanning the globe (e.g., Antarctic, tropical, temperate, boreal, alpine, Arctic systems). We show that widespread changes in river DSi concentration and yield have occurred, with the most substantial shifts occurring in alpine and polar regions. The magnitude and direction of trends varied within and among biomes, were most strongly associated with differences in land cover, and were often independent of changes in river discharge. These findings indicate that there are likely diverse mechanisms driving change in river Si biogeochemistry that span the land‐water interface, which may include glacial melt, changes in terrestrial vegetation, and river productivity. Finally, trends were often stronger in months outside of the growing season, particularly in temperate and boreal systems, demonstrating a potentially important role of shifting seasonality for the flux of Si from rivers. Our results have implications for the timing and magnitude of silica processing in rivers and its delivery to global oceans.

Influence of Anthropogenic Sulfuric Acid on Different Lithological Carbonate Weathering and the Related Carbon Sink Budget: Examples from Southwest China

Accurate estimate of carbonate weathering and the related carbon sink flux induced by anthropogenic H2SO4 is of great significance for improving understanding of the hydrogeochemical evolution and the global carbon cycle. Here, to quantitatively evaluate the influence of anthropogenic H2SO4 on different lithological carbonate weathering and the related carbon sink budget, karst spring water in the typical limestone and mixed limestone–dolomite catchments in Yaji and Beidiping affected by acid precipitation in southwest China were sampled monthly for the analysis of hydrochemical and δ13CDIC characteristics. Results show for the period of sampling (August 2013 to December 2014) that the average contribution rates of atmospheric inputs and carbonate weathering to total dissolved cations are 2.24% and 97.8%, and 3.09% and 96.9% in Yaji and Beidiping, respectively. The δ13CDIC values (−17.0% to −14.7‰) and the [Ca2+ + Mg2+]/[HCO3−] (0.98 to 1.25) and [Ca2+ + Mg2+]/[HCO3− + SO42−] (approximately 1) equivalent ratios of samples prove that H2CO3 and H2SO4 simultaneously participate in carbonate weathering. The contribution rates of H2SO4 to [Ca2+ + Mg2+] and [HCO3−] produced by carbonate weathering in Yaji and Beidiping are 0–30% and 0–18%, and 0–37% and 0–23%, with average values of 14% and 7%, and 19% and 11%, respectively, suggesting that the influence of H2SO4 on different lithological carbonate weathering is different. H2SO4 precipitation participating in carbonate weathering increases the weathering rate by 14–19%, whereas it decreases the flux of karst carbon sink by 7–11% in Southwest China. Therefore, anthropogenic acids have influenced the global carbon cycle and climate change by carbonate weathering due to the large karst areas in the world, and their influences on different lithological carbonate weathering should not be ignored in the regional and global carbon cycles in future studies.

Two-dimensional modeling of CO2 mineral trapping through the oxalate‑carbonate pathway: Influence of the root system model

Two-dimensional reactive transport models, one with a simplified root system and the other accounting for dynamically evolving root architecture, were constructed to examine the influence of model complexity on capturing the effect of soil-root dynamics relating to the Oxalate Carbonate Pathway (OCP) of the Iroko tree over 170 years. Oxidation of oxalate from fallen tree tissue by soil bacteria enables local soil pH increase, leading to the sequestration of atmospheric carbon in carbonate minerals (calcite) in the shallow soil surrounding the tree. Simulations of both root models corroborate previous one-dimensional models of the OCP focused on Ca and C mass balance, where high weathering rates of Ca-containing silicate minerals in bedrock, along with contributions from groundwater, provided sufficient Ca for precipitation of observed quantities of calcite. Both simulations demonstrate the development of a distinct high pH zone where oxalate is oxidized, Ca accumulates, and calcite precipitates (OCP zone); and a low pH zone where roots collect Ca, later returned to the top soil as calcium oxalate (Total Root Extent/TRE zone) via litterfall. While the extent of OCP zone development near the ground surface was very similar between simulations, differences in localized root water uptake between the two approaches resulted in variation in water and solute transport and influenced the geometry of the OCP zone at depth, with implications for calcite precipitation in the soil. Trends in CO2 and O2 partial pressures in the OCP zone were mirrored in the TRE zone, suggesting linkage between the two zones with regard to gas transport. Near the end of the tree's lifespan, results indicate that soil permeability decreases due to calcite precipitation may limit O2 ingress and availability in the shallow soil, while trapping CO2 released from the oxidation of organics in the shallow soil, with implications for the long-term sustainability of the OCP itself.

Comparative analysis of weathering rate of serpentine by microbial pure culture and field burial tests: A case study

The process of mineral weathering in nature is usually accompanied by biological actions, however, current laboratory studies on pure culture weathering minerals of various microorganisms (e.g., bacteria and fungi) lack comparisons on quantitative weathering indicators such as weathering rate or capacity with each other, let alone with in situ mineral weathering in the field. In this present research, to establish weathering models under different conditions and to conduct a quantitative comparative analysis, a specimen test method was used to study the weathering ability of serpentine under different types of microorganisms in the laboratory and field conditions. The results showed that, based on the weight loss of the test specimens and the change in the concentration of released Mg2+, the order of serpentine weathering rate was: Aspergillus niger > Esherichia coli > Bacillus subtilis > field tests. Accordingly, the amount of mineral weathering under natural conditions was compared with the amount of mineral weathering of experimentally pure cultured microorganisms and quantitative relations were established. The weathering ability of microorganisms cultured in the laboratory is much stronger than that under field conditions, because laboratory culture conditions are more suitable for microbial growth, which is very different from the environment in which those microorganisms grow in the field being usually in the state of starvation or semi-starvation. This study is expected to provide new ideas for estimating the effects of mineral weathering in the field over a longer time scale by using short-term laboratory weathering results.

Geochemical and mineralogical evidence for the formation of siderite in Late Permian coal-bearing strata from western Guizhou, SW China

This paper presents the results of the geochemical and mineralogical investigation of siderite in the Late Permian coal-bearing strata from western Guizhou, SW China. Siderite occurs as fine-grained ooids, as recrystallized stellate-like forms, as ellipsoidal, rhombohedral, and oolitic aggregates, indicating their authigenic origin. In contrast, pore filling and veinlet siderite are of epigenetic origin. The low sulfur contents, absence of pyrite, and Sr/Ba ratios indicate that the siderite was deposited in a freshwater (non-marine) environment. The V/(V + Ni) values of studied samples, ranging from 0.68 to 0.86, indicate that the siderite developed under anoxic conditions. The presence of authigenic kaolinite and epigenetic siderite in the same samplesuggests that the chemical conditions changed from acidic to alkaline conditions during early diagenesis.Iron in the siderite was not only derived from silicate weathering of high-Ti basalts in the sediment source regions followed by transport as ions by ground and surface waters, but was also generated from in situ alteration of the Fe-bearing minerals within the peat itself. In addition, ascending hydrothermal solutions would also contribute some Fe, with the Fe probably sourced from the leaching of the basaltic basement. The presence of siderite-rich layers indicates enhanced chemical weathering rates in the sediment source regions. The δ13CPDB, δ18OPDB, and δ18OSMOW values of siderite in claystones and mudstones vary within the ranges of −7.7 to 5.8‰, −12.1 to −6.6‰, and 18.4 to 24.1‰, respectively, indicating that carbon and oxygen primarily originated from marine carbonate, dehydroxylation of organic matter, carbonate dissolution, and hydrothermal fluids. The released CO2 invoked the alteration of reactive silicate minerals in the sediments, and ultimately the formation of siderite. Circulating pore fluids dissolving iron, which is derived from the silicate weathering of high-Ti basalts in the sediment source regions and from in situ alteration of the Fe-bearing minerals within the peat, would transport some iron from the overlying peat into the underlying sediments, and the flow of fluids would be diminished or stopped at the base of the peat due to the mechanical barrier of the impervious claystone or mudstone layers. The ferrous iron was precipitated due to the alkaline environment conditions of the peat, by reaction with HCO3− dissolved in the waters to form siderite.

The weathering process of carbonatite: weathering time.

Soil formation by rock weathering is driven by a combination of parent material, climate, organisms, topography, and time. Among these soil-forming factors, time plays a pivotal role in the weathering of carbonatite but it is a challenging factor to study quantitatively. A method for determining the weathering duration of carbonatite based on its weathering characteristics over a century-scale time period has not been clearly established. In this study, we selected abandoned carbonatite tombstones commonly found in the karst region of southwest China for investigation, using the date when the tombstones were erected as the onset of weathering. Chemical weathering indices were used to evaluate the weathering degree of different oxide contents produced by the carbonatite weathering process. In order to explore the weathering characteristics over time, the relationship between weathering duration and weathering degree was established. The results showed the following: (1) magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), titanium (Ti) are gradually enriched in the carbonatite regolith, and calcium (Ca) is gradually reduced. (2) The chemical indices of alteration (CIA), leaching coefficient (Lc), alumina-to-calcium ratio (AC) and mobiles index (Imob) can be successfully used for evaluation of the weathering degree of the carbonatite in different weathering time periods. (3) During the weathering of carbonatite, the weathering rate is a logarithmic function of time. Our research shows that over a period of more than 100 years of weathering, the carbonatite weathering process is characterized by fast weathering rates and low weathering degree in the early stages, but slow weathering rates in the later stages.

From site to state – Quantifying multi-scale legacy effects of historic landforms from charcoal production on soils in Connecticut, USA

Relict charcoal hearth (RCH) landforms are relatively small (average diameters of 11 m) and circular microrelief features found in many forests of the North-Eastern USA and Central Europe. Soils on RCHs are special in that they are significantly enriched in organic- (OC) and pyrogenic carbon (PyC), caused by the admixture of charcoal. Many studies have shown that this results in changed soil chemical and physical properties, making RCHs unique soil microhabitats. However, questions about their larger impact on a soil landscape’s carbon storage have hardly been studied so far; an aspect that could become more relevant with growing RCH site location databases. Here we show that RCHs can substantially add to a landscape soil organic- and pyrogenic carbon storage. This effect is scale dependent, i.e. a larger scale of observation (1:20,000) will result in significant additions for areas with high site densities (+22.6 % OC, +128.6 % PyC), contrary to smaller scales of observation (>1:650,000) where the effect is diminished (+0.2 % OC, +1.2 % PyC). A comparison with a nationwide soil database (gSSURGO) shows that in areas with high site densities, individual soil unit OC contents are increased by up to 91.6 %. An exemplary comparison to historic terrace/lynchet systems shows that RCHs store vastly more carbon when pedons of the same size are compared. However, if the actual landform surface areas are taken into account, RCHs store a lot less. This is showcasing the spot-like distribution of RCHs on a landscape scale. Furthermore, we broaden the knowledge about RCH site specific properties in Connecticut by a first analysis of pedogenic (hydr-)oxide and exchangeable cation concentrations, with the result indicating increased weathering rates and enrichment of exchangeable Ca2+, Mg2+ and Mn2+ in RCH soils.

Experimentally-calibrated estimation of CO2 removal potentials of enhanced weathering

Enhanced weathering (EW) of (ultra)mafic rocks is widely considered as a promising option for carbon dioxide removal (CDR). However, accurately measuring its CDR potential remains unavailable due to sluggish weathering process. Previous models have estimated annual CDR potentials ranging from 1 to 95 Gt by 2100, with the maximum significantly exceeding the anthropogenic CO2 emissions in 2021 (approximately 41 Gt). This raises concerns that a misconception may arise, suggesting active mitigations of CO2 emissions might not be necessary. Herein, we address this issue by partitioning the CDR potential of EW into two components, flow-through and non-flow-through processes, and develop an experimentally-calibrated model to reduce discrepancies between previous theoretical and experimental weathering rates. Our model estimates the upper bound of CDR potentials to be 0.22 (±0.16) Gt annually and 17 (±13) Gt cumulatively by 2100, thereby emphasizing the significance and urgency to advance ultra-enhanced weathering strategies.

Chemical weathering detection in the periglacial landscapes of Maritime Antarctica: New approach using geophysical sensors, topographic variables and machine learning algorithms

The chemical weathering intensity in Antarctica is underestimated. As the chemical weathering intensity increases, hydrological, geochemical and geophysical changes occur in the different environmental spheres and at their interfaces through reactions and energy flows. Thus, once chemical weathering rates are understood and estimated, they can be used to predict and assess changes and trends in different environmental spheres. Few studies on the chemical weathering intensity have been performed in Antarctica. We used radiometric and magnetic properties associated with terrain attributes and the chemical degree of alteration of the igneous rock to model the chemical weathering intensity in Maritime Antarctica by using machine learning. Then, we related the chemical weathering intensity and geophysical variables with periglacial processes. To do this, gamma-spectrometric and magnetic readings were carried out using proximal-field sensors at 91 points located on different lithologies in a representative area of Maritime Antarctica. A qualitative analysis of chemical alteration for the different lithologies was carried out based on field observations and rock properties, and the levels of the chemical weathering degree were established. The geophysical data associated with terrain attributes were used as input data in the modeling of the weathering intensity. Then, the levels of the rock weathering degree were used as the “y” variable in the models. The results indicated that the C5.0 algorithm had the best performance in predicting the weathering intensity, and the most important variables were eTh, 40K, 40K/eTh, 40K/eU, the magnetic susceptibility and terrain attributes. The contents of radionuclides and ferrimagnetic minerals in different lithologies, concomitantly with the intensity at which chemical weathering occurs, determine the contents of these elements. However, the stability and distribution of these elements in a cold periglacial environment are controlled by periglacial processes. The chemical weathering intensity prediction model using gamma-spectrometric and magnetic data matched the in situ estimate of the chemical degree of alteration of the rock. The pyritized andesites showed the highest intensities of weathering, followed by tuffites, diorites, andesitic basalts and basaltic andesites, and the lowest weathering intensity was shown by undifferentiated marine sediments. This work highlighted the suitability of using machine learning techniques and proximal-field sensor data to study the chemical weathering process on different rocks in these important and inhospitable areas of the cryosphere system.

Hydrochemistry and strontium isotope fingerprints of solute sources and CO2 consumption in Changbai Mountain area, Northeast China.

As one of the most representative forms of groundwater, mineral water provides a critical understanding of regional hydrogeochemical features and rock weathering processes. However, current studies have mostly focused on the quality of mineral water and have rarely addressed the weathering process during its formation. Therefore, a multi-tracer approach combines chemical parameters, major ions, selected trace elements, and 87Sr/86Sr ratios for mineral water samples in Changbai Mountain during 2020-2021. First, we determined the hydrogeochemical characteristics of different types of mineral water. Secondly, the water-rock interaction processes governing the water mineralization were described to fix the hydrogeochemical background. Thirdly, the chemical weathering rate was calculated. The total dissolved load generated by rock weathering was around 6.76 tons/km2/year in the mineral water catchment area; 44.6% and 36.9% of the dissolved load were derived from silicate and carbonate weathering, respectively. The trace carbonates also played an important role in the overall rock weathering. Finally, after fully considering various influencing factors, we concluded that lithological characteristics and the soil environment rich in organic acids were the most important factors affecting rock weathering in the Changbai Mountain area. Overall, this study highlights the mineral water's role in the fluxes of CO2 in local area and reveals possible influence of the unique ecological and geological environment on rock weathering in Changbai Mountain. It can provide a reference for the subsequent assessment of environmental stability for basalt areas and the possibility of sustainable water resources development.

Microplastic–Pharmaceuticals Interaction in Water Systems

Microplastics, MPs, in aquatic environments pose serious threats when associated with other pollutants, such as pharmaceuticals, PHs. This review is a continuation of an earlier paper on the role of MPs as containers and carriers of heavy metals, HMs, persistent organic pollutants, POPs, pharmaceuticals, PHs, and personal care products, PCPs, in marine environments and published in the Journal of Marine Science and Engineering. The current effort aims to elucidate the most recent data on the interaction and association of MPs with PHs and the ecotoxicological implications on food webs. This review focuses on the nature of the interaction from different perspectives, such as the hydrophobicity and hydrophilicity of the polymer and drug, the polymer surface, and the rate of weathering. The effects of environmental conditions, such as mechanical stress, photodegradation, pH, salinity, dissolved organic matter, and gastrointestinal features of marine biota, were reported. This review reports on experimental laboratory, mathematical, and field data on MPs’ carrier and accumulation role in PHs and their release and ecotoxicological effects on water bodies. From the survey of the data, it emerges that the nature of the interaction and the effects on biota are very complex and variable, and perhaps only a systematic mechanic approach of data collection with a statistical approach using big data and deep learning will contribute in the future to clarify.

Chemical weathering rates and controlling mechanisms of glacial catchments within different climate regimes in the Tibetan Plateau.

Continental weathering plays an important role in regulating atmospheric CO2 levels. Chemical weathering in glacial areas has become an intensely focused topic in the background of global change compared with other terrestrial weathering systems. However, research on the weathering of the glacial areas in the Yarlung Tsangpo River Basin (YTRB) is still limited. In this article, the major ions of the Chaiqu and Niangqu catchments in the YTRB have been investigated to illustrate the chemical weathering rates and mechanisms of the glacier areas in the YTRB. Ca2+ and HCO dominate the major ions of the Chaiqu and Niangqu rivers, accounting for about 71.3% and 69.2% of the TZ+ of the Chaiqu (the total cations, TZ+ = Na+ + K+ + Ca2+ + Mg2+, in µeq/L), and about 64.2% and 62.6% of the TZ+ of the Niangqu. A Monte Carlo model with six end-members is applied to quantitatively partition the dissolved load sources of the catchments. The results show that the dissolved loads of the Chaiqu and Niangqu rivers are mainly derived from carbonate weathering (accounting for about 62.9% and 79.7% of the TZ+, respectively), followed by silicate weathering (about 25.8% and 7.9% of the TZ+, respectively). The contributions of precipitation and evaporite to the Chaiqu rivers are about 5.0% and 6.2%, and those to the Niangqu rivers are about 6.3% and 6.2%. The model also calculated the proportion of sulfuric acid weathering in the Chaiqu and Niangqu catchments, which account for about 21.1% and 32.3% of the TZ+, respectively. Based on the results calculated by the model, the carbonate and silicate weathering rates in the Chaiqu catchment are about 7.9 and 1.8 ton km-2 a-1, and in the Niangqu catchment, the rates are about 13.7 and 1.5 ton km-2 a-1. The associated CO2 consumption in the Chaiqu catchment is about 4.3 and 4.4 × 104 mol km-2 a-1, and about 4.3 and 1.3 × 104 mol km-2 a-1 in the Niangqu catchment. The chemical weathering rates of the glacier areas in the YTRB show an increasing trend from upstream to downstream. Studying the weathering rates of glacier catchments in the Tibetan Plateau (TP) reveals that the chemical weathering rates of the temperate glacier catchments are higher than those of the cold glacier catchments and that lithology and runoff are important factors in controlling the chemical weathering of glacier catchments in the TP. The chemical weathering mechanisms of glacier areas in the YTRB were explored through statistical methods, and we found that elevation-dependent climate is the primary control. Lithology and glacial landforms rank second and third, respectively. Our results suggest that, above a certain altitude, climate change caused by tectonic uplift may inhibit chemical weathering. There is a more complex interaction between tectonic uplift, climate, and chemical weathering.

Reconstructing a 51-year record of catchment scale dissolved load for the Haast/Awarua River in the Southern Alps, New Zealand

Mountains dominate global denudation fluxes of solutes to the oceans despite being only a modest portion of the Earth's surface. Determining the flux of material exhumed from mountains as dissolved load, however, requires careful measurement of ionic concentrations and discharge that may be hard to obtain. We reconstruct the dissolved load and total dissolved solids yield from pre-existing discharge measurements and 32-years on monthly water quality sampling in a headwater catchment in the Southern Alps/Ka Tiritiri o te Moana, New Zealand. The dissolved weathering yield of the Haast/Awarua River for 1971–2020 was 218 ± 48 t km−2 a−1. The flux of dissolved material from the mountain catchment has a seasonal signal, with higher TDS concentrations during winter, but greater chemical weathering yields during summer. Hydrographic behaviour is an important control of weathering yields with 70 % of dissolved load being transported during event flow. Variations in chemical weathering yields are sensitive to changes in stream flow associated with broader climate oscillations, which will have a direct effect on estimations of chemical weathering rates since dissolved flux is strongly correlated to changes in stream flow.

Сравнительная характеристика литохимических особенностей черноземов северного Приазовья и Крыма

The article discusses modern approaches to the study of weathering and soil formation processes in soils. It offers comparative characteristics of migration-segregation (ordinary carbonate) chernozems and textural-calcareous (southern) chernozems formed under conditions of the steppe regions in the Crimea and Rostov region. Lithochemical indices were used to determine the relative age of soils and establish the relationship between soil formation and weathering. CIA index characterizes the degree of soil weathering and its mineralogical features, while CIW index determines the degree of maturity of fine aluminosiliciclastics. The determined gross chemical (elemental) composition of soils and rocks formed the initial data for such reconstructions. In addition, the research included calculations of the molar ratios of silica to sesquioxides (SiO2:R2O3) and the eluviation coefficient (Ke) (excluding sodium) in soils and soil-forming rocks. It has been established that the relative age of chernozems in the Crimean Peninsula is less compared to the similar subtypes of chernozems in the Rostov region. This is due to the peculiarities of the soil-forming material. In the Rostov region, chernozems are formed on more weathered clay parent rocks, while the formation of Crimean chernozems is confined mainly to the eluvium of sedimentary rocks. Down the profile, the intensity of soil formation and weathering processes in the soils of the South and South-East of the East European Plain noticeably decreases due to a lower rate of secondary weathering of minerals. This can be explained by the limited energy characteristics of the environment in which these processes occur. Among such limiting environmental factors, on the major factors are an insufficient amount of moisture in the spring-summer period.

Chemical weathering of small watersheds in the upper reaches of Jinsha river on the eastern edge of the Qinghai–Tibet Plateau

Land chemical weathering is a crucial and common geological process on the Earth’s surface. Studying the surface chemical weathering process in basins is important to the net consumption rate of atmospheric CO2, climate change in geological history, and the global carbon cycle. In this study, a small watershed in the upper reaches of Jinsha River on the eastern edge of the Qinghai-Tibet Plateau is selected as the study area. By measuring the physical and chemical properties and the main ion content of the water in the watershed and by using the factor analysis method, the source of the main ion components in the water in the alpine basin and the characteristics of the chemical weathering of the basin rocks are examined. Results show that the pH value of surface water in the study area varies from 7.4 to 8.2, and the overall performance is moderately to weakly alkaline. The total salinity in the basin is between 52.42 and 398.19 mg/L, with an average value of 180.06 mg/L. The concentration of main cations in surface water follows the order Ca2+>Mg2+>Na+>K+. The concentration relationship of the main anions is in the order HCO3−>SO42−>Cl−, and the hydrochemical type is HCO3_Ca. The main source of ions in the study area is rock weathering, which is controlled by the chemical weathering of carbonate rocks. The contribution rates of carbonate (mainly dolomite and calcite dissolution), evaporite, and silicate to the dissolved matter in the river are 59.40%, 7.30%, and 3.00% respectively, and the contribution rate of CO2 in the atmosphere to the dissolved matter in the river is 30.30%. The total chemical weathering rate in the study area is 29.09 t/km2 ⋅a, which is at a low level, indicating that weak hydrothermal conditions slow down the chemical weathering process of rock minerals.