Rock Weathering Research Articles

Formation Mechanism and Source Apportionment of Hydrochemical Components in Groundwater in the Yinchuan Plain

Groundwater is one of the major water sources for production, living, and agricultural irrigation in the Yinchuan Plain. Owing to the influence of the regional environmental background and long-term effects of human activities, groundwater quality is generally inferior. To deeply analyze the formation mechanism and source of hydrochemical components in groundwater in the Yinchuan Plain, the traditional hydrochemical graphic method and mathematical statistics and principal component analysis-multivariate linear statistical model were used. Based on inorganic component contents of 100 phreatic water samples and 46 confined groundwater samples, the hydrochemical characteristics and quality status, spatial distribution of over-limit toxicological components, and contribution rate of hydrochemical components were analyzed. The results showed that the chemical components of groundwater were controlled by rock weathering and evaporation concentration. Dissolution-enrichment （F1）, original geological environment （F2）, and human activities（F3） were the principal factors that influenced groundwater hydrochemistry with the contribution rates of 73.67%, 14.45%, and 11.88%, respectively. The major over-limit toxicity indices in groundwater were NO3--N and F-. High NO3--N phreatic water was mainly influenced by agriculture activities, followed by the discharge of domestic sewage. Enrichment of groundwater F- was mainly caused by leaching of F-bearing minerals and cation exchange adsorption.

Characteristics of Water Environment and Its Influencing Factors in Zhari Namco Basin, Xizang

Zhari Namco is situated in the alpine grassland belt of northwestern Xizang with a fragile ecological environment. As the third-largest lake in Xizang, there has been a long-term lack of research data concerning its basin water environment. In an effort to elucidate the surface water environment characteristics of the basin and the factors influencing them, an extensive investigation was conducted from August 2021 to June 2022, encompassing periods of high flow, low flow, and base flow. Further, the study also involved comprehensive assessments of the water chemistry characteristics and spatial-temporal variation in lake sampling sites of the basin that were not significant by using mathematical statistics, hydrochemical analysis, correlation analysis, and principal component analysis. The findings revealed the following： ① The water in the Zhari Namco Basin exhibited an alkaline nature, with dominant ionic compositions in the lake comprising Na+, SO42-, and Cl-, whereas the rivers were primarily characterized by Ca2+, HCO3-, and SO42-. ② The main pollutants exceeding established standards included sulfates, arsenic, chlorides, and total phosphorus. The study identified significant spatiotemporal variations in water quality. Temporally, the exceedance of sulfates, arsenic, and total phosphorus was most pronounced during high-flow periods, followed by that during low-flow and base flow periods, with chloride levels showing less temporal variation. Spatially, river water quality surpassed that of the lakes, with arsenic, total phosphorus, TDS, sulfate, chloride, K+, and Na+ concentrations in lakes 1 to 2 orders of magnitude higher than those in rivers. Water qualities exceeding the established standard were primarily found in the lake, with less spatial variations within the lake itself. ③ Hydrochemical processes within the basin were found to be primarily influenced by natural phenomena, including evaporation-concentration and rock weathering. Various elements entered the lakes via surface runoff, where they continuously accumulated under the influence of evaporation-concentration processes, ultimately leading to exceedances. ④ Temporal variations in water quality were primarily attributed to increased elemental loss and intensified evaporation during high-flow periods. The spatial discrepancies in water quality were predominantly a consequence of the differing hydrodynamic conditions between flowing water bodies and enclosed water bodies.

Dissolved trace elements in the upper reaches of Lancang River, southeast Qinghai-Tibet Plateau: Current status and distribution, risk and source

The environmental impact of dissolved trace element (DTE) pollution is becoming increasingly well understood. The southeastern edge of the Qinghai-Tibet Plateau is a region with high environmental vulnerability, making it highly susceptible to various anthropogenic disturbances. The Lancang River (LCR), as the most representative river in this area, serving as the largest international river in Southeast Asia, the LCR is crucial for the downstream regions, supporting fisheries, agriculture, and even economic development, earning it the title of the “water tower” for these areas. This study mainly focuses on the upstream unbuilt dam area. In this study, we gathered 25 surface water samples from the upstream of the LCR and examined the geographical distribution, primary sources, and associated human health risks of seven dissolved trace elements (Mn, Cr, Fe, Co, Cu, Ni, Zn). Cr, Fe, Co, Ni, and Cu in the main stream are primarily associated with natural sources, including rock weathering, soil erosion, and similar processes. Mn, however, predominantly originates from human activities such as industrial construction and road transportation. Zn mainly originates from the specialized fertilizers used for highland barley in plateau regions. Almost all DTE concentrations exhibited a downward trend from upstream to downstream. However, due to inputs from various sources along the way, there will be some abnormal points. The concentrations of DTE in the study area were within the acceptable limits set by drinking water standards in China, the USA, and the WHO. Overall, the water quality in this region is considered good. The results from a Monte Carlo simulation assessing health risks indicate that the non-carcinogenic health risk caused by DTE in the upper reaches of Lancang River was very weak. The primary pathway through which DTE can harm human health is ingestion, with children being particularly vulnerable. These findings offer a critical scientific basis for understanding the migration of DTE in aquatic environments and for the ecological stewardship of the Lancang River.

Quantitative analysis of dissolved carbon sources in the farmland artificial ditch drainage-Lake UlanSuhai continuum in the Hetao Irrigation District's, Inner Mongolia

Study regionAgricultural Irrigation and Drainage system - Ulansuhai Lake Continuum, located in the Hetao Irrigation District, Inner Mongolia, China. Study focusIn this study, carbon isotope tracing technology was applied to analyze the sources and migration-transformation characteristics of Dissolved Organic Carbon (DOC) and Dissolved Inorganic Carbon (DIC) in the continuous system of the agricultural irrigation and drainage system - Ulansuhai Lake in the Hetao Irrigation Area of Inner Mongolia during typical irrigation periods. New hydrological insights for the regionDuring typical irrigation periods, DOC and DIC increase simultaneously with the increase in salinity, and dissolved carbon dioxide in the irrigation and drainage channels escapes. The main sources of DOC in farmland drainage water are terrestrial C3 plants (94.00 %) and plankton (6.00 %). The primary sources of DOC in the lake are farmland drainage (98.19 %) and macroaquatic plants (1.81 %). The main sources of DIC in farmland drainage water are irrigation water from the Yellow River (64.73 %) and the equilibrium dissolution process between carbonates and soil CO₂ (35.27 %); while the primary sources of DIC in the lake are farmland drainage (93.10 %) and air-water exchange (6.90 %). Crop types in the irrigated area, soil salinization, rock weathering, metabolic processes, and the hydrological connectivity induced by irrigation from the Yellow River jointly control the sources, migration, and transformation of carbon within the continuum.

Enhanced silicate weathering accelerates forest carbon sequestration by stimulating the soil mineral carbon pump.

Enhanced silicate rock weathering (ERW) is an emerging strategy for carbon dioxide removal (CDR) from the atmosphere to mitigate anthropogenic climate change. ERW aims at promoting soil inorganic carbon sequestration by accelerating geochemical weathering processes. Theoretically, ERW may also impact soil organic carbon (SOC), the largest carbon pool in terrestrial ecosystems, but experimental evidence for this is largely lacking. Here, we conducted a 2-year field experiment in tropical rubber plantations in the southeast of China to evaluate the effects of wollastonite powder additions (0, 0.25, and 0.5 kg m-2) on both soil organic and inorganic carbon at 0-10 cm depth. We found that ERW significantly increased the concentration of SOC and HCO3 -, but the increases in SOC were four and eight times higher than that of HCO3 - with low- and high-level wollastonite applications. ERW had positive effects on the accrual of organic carbon in mineral-associated organic matter (MAOM) and macroaggregate fractions, but not on particulate organic matter. Path analysis suggested that ERW increased MAOM mainly by increasing the release of Ca, Si, and Fe, and to a lesser extent by stimulating root growth and microbial-derived carbon inputs. Our study indicates that ERW with wollastonite can promote SOC sequestration in stable MOAM in surface soils through both the soil mineral carbon pump and microbial carbon pump. These effects may have been larger than the inorganic CDR during our experiment. We argue it is essential to account for the responses of SOC in the assessments of CDR by ERW.

Design, TEA, and LCA of reactor-based bio-enhanced rock weathering

Design, TEA, and LCA of reactor-based bio-enhanced rock weathering

Hydro-chemical characteristics of Biring and Tangting Rivers (Nepal) and evaluation of water quality for drinking and irrigation purposes

Although river water is vital for drinking, irrigation and domestic needs, it faces threats from natural processes and human activities. Small and medium-sized rivers, especially in Nepal, remain understudied despite their vital importance in providing water to densely populated areas. This study evaluated the suitability for drinking and irrigation and the hydro-chemical characteristics of the Biring and Tangting rivers in Koshi province, Nepal. The results showed that turbidity, pH, EC, TDS, TH, NH4+, K+, Ca2+, Mg2+, Na+, Cl−, SO42−, HCO3− and NO3− values of all sampling sites in the Biring and Tangting rivers, except for the turbidity value of 10.39 NTU recorded in the PT9 site of the Tangting River, did not exceed maximum limit values set for drinking water. However, according to Water Quality Index results, the water of both rivers was in poor condition for drinking due to domestic wastewater discharges and cremation activities which caused high NH4+ levels. The major cations in both rivers were listed as Ca2⁺ > Na⁺ > K⁺ > Mg2⁺, while the major anions were listed as HCO₃⁻ > Cl⁻ > SO₄2⁻ > NO₃⁻. Gibbs and Piper diagrams showed that geogenic weathering of carbonate rocks prevailing in the region affected the hydrochemistry in both rivers. Evaluation based on seven different irrigation indices and US salinity laboratory diagram revealed that the water of both rivers was suitable for irrigation despite some magnesium-related limitations.

Sensitivity of ordinary rock weathering tests to acid rock drainage

Sensitivity of ordinary rock weathering tests to acid rock drainage

Minority groups, Indigenousness and Indigeneity, and place in social perceptions of future climate interventions

Radical climate intervention technologies such as carbon dioxide removal and solar radiation management pose difficult questions as potential remedies for destructive climate change. The effect these technologies could have on Indigenous peoples and minority groups, and those living in rural areas, could be profound and potentially calamitous. Drawing on a large-scale, cross-country set of nationally representative surveys (n = 30,284 participants, with at least 1,000 in each country) in 30 countries and 19 languages, this article examines public preferences for climate intervention technologies through the three dimensions of minority groups, Indigenousness, and place. The survey explores 10 climate intervention or geoengineering technologies: stratospheric aerosol injection, marine cloud brightening, space-based geoengineering, afforestation and reforestation, soil carbon sequestration, blue carbon and marine biomass, direct air capture with carbon storage, bioenergy with carbon capture and storage, enhanced rock weathering, and biochar. Comparing the full sample of respondents with a subsample self-identifying as ethnic minorities or Indigenous peoples, it finds this latter category of respondents has greater familiarity with these technologies than non-members, are more positive about small-scale trials and have more positive attitudes towards engineered options (versus nature-based options). Those in cities also expressed stronger support for small-scale field trials. Moreover, members of Indigenous groups or ethnic minorities expressed significantly higher levels of support for small-scale trials for nearly all technologies, were more supportive of policy incentives, and, inter alia, less supportive of policy restrictions. Conversely, non-members of Indigenous or ethnic minority groups expressed small but significantly greater support for independent national restrictions being placed on solar radiation management and engineered forms of carbon removal.

Grain Size in Landscapes

Earth's terrestrial topography evolves in response to the interaction of tectonics, climate, and lithology. Recent discoveries suggest that the grain size of sediments produced on hillslopes and transported through river networks is key to understanding these interactions. Hillslope grain size varies systematically with erosion rate and residence time, the degree of chemical and physical weathering, and the fracture density and susceptibility to weathering of rock. Variations in initial grain size strongly influence the spatial evolution of grain size distributions as particles mix and wear during downstream transport through channel networks. In rivers, the size and flux of the coarse fraction of the sediment load control the rate of incision into bedrock and thus govern channel slope and ultimately the relief of actively eroding landscapes. These relationships suggest that a primary way that tectonics, climate, and lithology influence landscape evolution is through their controls on sediment grain size. ▪Recent research reveals the central role of sediment grain size in controlling bedrock river morphodynamics, linking grain size to channel slope and topographic relief.▪Tectonics, climate, and lithology govern the size of sediments produced on hillslopes; hence, grain size mediates their influence on landscape evolution.▪Feedbacks linking sediment grain size, topography, weathering, erosion, and sediment transport provide new opportunities for advances in Earth surface science.

Reduced accrual of mineral-associated organic matter after two years of enhanced rock weathering in cropland soils, though no net losses of soil organic carbon

Enhanced rock weathering (ERW), the application of crushed silicate rock to soil, can remove atmospheric carbon dioxide by converting it to (bi) carbonate ions or solid carbonate minerals. However, few studies have empirically evaluated ERW in field settings. A critical question remains as to whether additions of crushed rock might positively or negatively affect soil organic matter (SOM)—Earth’s largest terrestrial organic carbon (C) pool and a massive reservoir of organic nitrogen (N). Here, in three irrigated cropland field trials in California, USA, we investigated the effect of crushed meta-basalt rock additions on different pools of soil organic carbon and nitrogen (i.e., mineral-associated organic matter, MAOM, and particulate organic matter, POM), active microbial biomass, and microbial community composition. After 2 years of crushed rock additions, MAOM stocks were lower in the upper surface soil (0–10 cm) of plots with crushed rock compared to unamended control plots. At the 2 sites where baseline pre-treatment data were available, neither total SOC nor SON decreased over the 2 years of study in plots with crushed rock or unamended control plots. However, the accrual rate of MAOM-C and MAOM-N at 0–10 cm was lower in plots with crushed rock vs. unamended controls. Before ERW is deployed at large scales, our results suggest that field trials should assess the effects of crushed rock on SOM pools, especially over multi-year time scales and in different environmental contexts, to accurately assess changes in net C and understand the mechanisms driving interactions between ERW and SOM cycling.

Hydrochemical and Formation Mechanism Studies of Groundwater in Quaternary Aquifer in a Northern Plain of China: An Example of Beijing Plain

Beijing Plain is a very active part of Beijing city regarding the socio-economic and human activities of the region. Over the past four decades, Beijing’s economic development and the continuous drought for nearly 10 years in the 2000s have negatively impacted the groundwater quantity and quality. Therefore, it is necessary to investigate the present situation of groundwater chemistry in this region to develop a comprehensive database and orientation for future research on groundwater quality evaluation. Mathematical statistics, Piper’s trilinear diagram, Gibbs plots, the ion ratio method and PHREEQC software 3.7.3 were used to analyze the groundwater hydrogeochemical characteristics and formation mechanisms of the quaternary aquifers of the Beijing Plain area. Hydrogeochemical results indicated that the groundwater is slightly alkaline, with pH values ranging from 6.76 to 8.65 and an average value of 7.92. The order of major cations in groundwater was Ca2+ > Na+ > Mg2+ > K+ with average values of 66.54 mg/L, 50.58 mg/L, 23.78 mg/L, and 1.81 mg/L, respectively, while the order of major anions was HCO3− > SO42− > Cl− with average values of 284.89 mg/L, 52.1 mg/L and 35.5 mg/L, respectively. The groundwater chemical types are Mg-Ca-Cl-HCO3, Na-Ca-HCO3, Mg-Ca-HCO3 and Mg-Na-HCO3. Research on the main influencing factors and PHREEQC hydrogeochemical inverse simulations results along the four pathways selected confirmed that rock weathering with sulfate, silicate and carbonate rock mineral dissolution and Na+, Mg2+ and Ca2+ ion reaction exchange influenced groundwater hydrogeochemical characteristics of the quaternary aquifers of the Beijing Plain area. Understanding the formation mechanisms of hydrogeochemistry in quaternary plains provides guidance for future studies and, through suggestions and case studies, facilitates decision-making by policy-makers on the sustainable management of groundwater resources.

Hydrochemical Characteristics and Controlling Factors of the Mingyong River Water of the Meili Snow Mountains, China

The hydrochemical characteristics of rivers are affected by many natural factors, such as the nature of watershed bedrock, watershed environment, vegetation, and human activities. Examining the hydrochemistry of a river can provide insights into the baseline hydrological conditions, the geochemical environment, and the overall water quality of the river. In order to examine the hydrochemical characteristics and controlling factors of the water in the Mingyong River, a total of 154 water samples were gathered from the glacier meltwater, midstream, and downstream regions. Firstly, the findings revealed that the dominant cations are Ca2+ and Mg2+, while the dominant anions are HCO3− and SO42−. The mass concentration order of cations is Ca2+ > Mg2+ > Na+ > K+, and for anions, it is HCO3− > SO42− > NO3− > Cl−. The average concentration of TDS in the river water is 81.69 mg·L−1, with an average EC of 163.63 μs·cm−1 and an average pH of 8.99. Temporal variations in ion concentrations exhibit significant disparities between the glacier melting and accumulation periods. High ion concentration values are primarily observed during the glacier accumulation period, while values decrease during the glacier melting period due to increased precipitation. The river water in the study region is categorized as (HCO3− + SO42−)-(Ca2+ + Mg2+) type. Secondly, the Pearson correlation analysis indicates clear relationships between different parameters, indicating that the major ions were mostly influenced by materials from the Earth’s crust. The primary principal source of solutes in the water of the Mingyong River is rock weathering. The cations and anions present in the river water are derived from the breakdown of carbonate rocks and the dissolving of substances from silicate rocks. However, the influence of carbonate rocks is more significant compared to that of silicate rocks. Finally, the Mingyong River water is suitable for agricultural irrigation with minimal land salinization damage, making it appropriate for agricultural purposes but not suitable for people and animals to drink from directly.

Integrated approach of predicting rock stability in high mountain valley underground caverns

High mountain valleys are characterized by the development of intricate ground stress fields due to geological processes such as tectonic stress, river erosion, and rock weathering. These processes introduce considerable stability concerns in the surrounding rock formations for underground engineering projects in these regions, highlighting the imperative need for rigorous stability assessments during the design phase to ensure construction safety. This paper introduces an innovative approach for the pre-evaluation of the stability of surrounding rocks in underground caverns situated within high mountain valleys. The methodology comprises several pivotal steps. Initially, we conduct inverse calculations of the ground stress field in complex geological terrains, combining field monitoring and numerical simulations. Subsequently, we ascertain stress-strength ratios of the surrounding rocks using various rock strength criteria. To assess the stability characteristics of the surrounding rocks in the 1# spillway cave within our project area, we employ numerical simulations to compute stress-strength ratios based on different rock strength criteria. Furthermore, we undertake a comparative analysis, utilizing data from the 5# Underground Laboratory (Lab 5) of Jinping II Hydropower Station, aligning the chosen rock strength criterion with the damage characteristics of Lab 5′s surrounding rocks. This analysis serves as the cornerstone for evaluating other mechanical responses of the surrounding rocks, thereby validating the pre-evaluation methodology. Our pre-evaluation method takes into account the intricate geological evolution processes specific to high mountain valleys. It also considers the influence of the initial geostress field within the geological range of underground caverns. This comprehensive approach provides a robust foundation for the analysis and assessment of the stability of surrounding rocks, especially in high mountain valley areas, during the design phase of underground engineering projects. The insights derived from this analysis hold substantial practical significance for the effective guidance of such projects.

Effects of a landslide on the geochemistry of dissolved major and trace elements in a granite-gneiss forest catchment of Southeast Brazil

This study investigated the hydrogeochemical variations in a scenario following a landslide event in the Soberbo pristine rainforest small catchment (13 km2). The selected catchment is underlain by granite gneiss and located at the Serra dos Órgãos a mountainous region in the Rio de Janeiro, Brazil, that faces frequent high-intensity rainfall events. Stream water sampling, water discharge, and pH and electrical conductivity measurements were conducted monthly from May 2018 to October 2019. In January 2019, a landslide occurred upstream. Concentrations of dissolved organic carbon (DOC), HCO3−, major elements (Ca, K, Mg, Na, and Si), and trace elements (Al, Ba, Ce, Fe, Mn, Nd, Sr, Rb, La, Pr and Sm) were determined. The Spearman correlation and the multivariate analysis (PCA) indicated that during baseflow, rock weathering hydrolysis reactions are the main source of Si, Na, Mg, Ba and Sr. On the other hand, the forest plays a significant role during the rainy months by remobilizing colloidal litter material (represented by the DOC concentration) closely associated with colloidal Al. The landslide promoted a change in local redox conditions, resulting in the early release of Mn-scavenged elements, and about a month later, Fe and LREE, following a deepening in reduced conditions. The Ce/La molar ratio appeared to be a reliable hydrogeochemical redox proxy. The landslide effects persisted for at least nine months. In this case, the traceability of natural geochemical impacts of landslides was achieved through the river hydrogeochemistry in a mountainous small catchment model area.

Assessment of groundwater fluoride and human health effects in a hard rock province of south India: Implications from Pollution Index Model (PIM) and GeographicalInformationSystem (GIS) techniques.

This research examines whetherthe groundwater in the Sivakasi Region of South India is suitable for consumption, and assesses the possible health hazards for various age demographics including infants, children, teenagers, and adults. A totalof 77 groundwater samples were gathered, covering a total area of 580km2 and analyzed for major and minor ions. The hydrogen ion concentration (pH) of the samples indicates neutral to marginally alkaline. The total dissolved solids (TDS) fluctuate from 255 to 2701mg/l and electrical conductivity varies from 364 to 3540µS/cm. A wide range of fluoride concentration was detected (0.1 to 3.2mg/l) with nearly 38% groundwater samples surpassing the proposed limit (1.5 mg/l) suggestedby the World Health Organization in 2017. Gibbs plot analysis suggested that most of thesamples were influenced by geogenic factors, primarily rock weathering in this region. Correlation analysis showed that most of the samples were impacted by both natural and human sources. The pollution index of groundwater (PIG) fluctuated from 0.67 to 2.60 with approximately 30% and 53% of samples falling into insignificant and low pollution categories, respectively. Furthermore, 10% and 5% of total samples were characterized as moderate and high pollution levels, and 2% asvery high pollution category. Spatial analysis using GIS revealed that 440.63km2 were within safe fluoride levels according to theWHO standards, while 139.32km2 were identified as risk zone. The principal component analysis (PCA1) showedstrong positive loadings on EC (0.994), TDS (0.905), Mg2+ (0.910), Cl- (0.903) and HCO3- (0.923) indicating rock water interaction. PCA2 accounts the high positive factor loading on HCO3- (0.864) indicating ion exchange and mineral leaching. The PCA1 and PCA2 indicated that variables such as mineral leaching and rock water interaction are themajor mechanisms contributing to the chemical signatures in groundwater, which may support for theelevated fluoride levels in certain areas. Risk assessments, including Hazard Quotient results showed that 71%, 61% 38%, and 34% of groundwater samples exceededthe permissible THI limit (THI > 1) for infants, children, teenagers, and adults, respectively. The study recommends implementing measures such as denitrification, defluorination, rainwater harvesting, and improved sanitation infrastructure to enhance the health conditions in the study region. Additionally, it suggests introducing educational programs in rural areas to create awarenessabout the health dangers due to consumptionof water with high fluoride levels.

Unexpected contributions by carbonates and organic matter in a silicate-dominated tropical catchment: An isotope approach

The understanding of global carbon has rarely extended to small-scale tropical river basins. To address these uncertainties, this study aims to investigate the importance of rock weathering and organic matter turnover in the carbon cycle in a terrain dominated by crystalline silicate rocks. The geochemical composition of the dissolved and particulate carbon phases (DIC, DOC and POC) and their stable carbon isotopes were studied in the Deduru Oya River in Sri Lanka. Dissolved inorganic carbon (DIC) was the most dominant carbon phase and its contribution to the total carbon pool varied between 67 and 89 %. Furthermore, the δ13CDIC values in the river varied between −1.1 and −16.5 ‰. The lithological characteristics and molar ratios between Ca2+, Mg2+ and HCO3− indicated rock weathering mainly by CO2 and carbonic acid. The δ13CDIC values for groundwater input were −15.9 ‰, while for carbonate weathering, mainly due to fertiliser input, they reached a value of −12.7 ‰. This input was fed into an isotope mass balance to determine the relative contributions. However, the isotope mass balance was only plausible after correcting for the effects on δ13CDIC caused by degassing and photosynthesis. Our study demonstrated that carbonate weathering and organic matter turnover are essential components of the river carbon cycle even in a silicate dominated catchment. They can represent up to 60 % of the DIC pool. Combined with the higher organic matter turnover and high pCO2 in the river water, it can be suggested that the Deduru Oya River acts as a net source of CO2 in the atmosphere. Our study shows that CO2 degassing and in-stream photosynthesis in tropical river systems need to be considered along with chemical weathering to account for carbon transport and turnover in tropical rivers.

Tree stumps as passive samplers for trace metal dust deposition

Atmospheric dust is contaminated by trace metals in many parts of the world due to human industrial activities. This study evaluates tree stumps as passive samplers of dust deposition and bioindicators of trace metal dust contamination in a mine impacted environment. Tree stumps (n = 230) and adjacent soils from Cu–Zn mining areas in northeastern China were analysed in situ for their trace metal concentrations using portable X-ray fluorescence (pXRF). Arsenic and Zn concentrations in tree stumps and roadside soils of each location all decreased with distance from the road in a power-law relationship, indicating a common pollution source (resuspension and redeposition of road dust). Micro-XRF images of vertical tree stump slices indicate that As and Zn were concentrated on the cut (uppermost) surface of tree stumps. This indicates atmospheric deposition as a primary contributor to elevated As and Zn concentrations in tree stumps. Trace metals in soils may have other sources besides atmospheric deposition (e.g., migration from buried ore-bodies or rock weathering), which may confound distinguishing sources in polluted areas. Here, we show that the analysis of tree stumps are suitable indicators of atmospheric trace metal contamination. Compared to surface soils, tree stumps can better reflect road dust resuspension and redeposition because unlike soils, atmospheric deposition is the primary contributor to their trace metal concentrations.

Hydrochemical characterization and health risk assessment of different types of water bodies in Fenghuang Mountain Area, Northeast China.

Groundwater, as an essential resource, holds significant importance for human production and livelihoods. With the deterioration of the water environment, the issue of groundwater quality has become an urgent international concern. This study focused on the Fenghuang Mountain Area (FMA) and collected a total of 41 sets of samples including pore groundwater (PGW), fissure groundwater (FGW), karst groundwater(KGW), and river water(RW). Hydrochemical analysis methods were employed to identify the hydrochemical characteristics and controlling factors. The entropy-weighted water quality index (EWQI) and health risk assessment model were utilized to assess the groundwater quality and nitrate health risk, respectively. The results indicated that the dominant anion and cation in both groundwater and surface water in the FMA were HCO3- and Ca2+, respectively, with the main hydrochemical type being HCO3-Ca. Groundwater and surface water in the FMA were primarily controlled by rock weathering process, with ion concentrations influenced mainly by the dissolution of halite, sylvite, carbonates (calcite and dolomite), silicates, and gypsum, as well as by reverse anion exchange process. PGW was significantly affected by agricultural activities, with NO3- concentration closely related to human activities. The water quality of FGW was relatively good, with Class I and Class II water accounting for the highest proportion, reaching 84.62%. The high-value area of EWQI in PGW was influenced by human activities. The impact of nitrate health risk on children was significantly greater than on adults, with FGW having the lowest health risk and PGW having the highest health risk. The research results can provide important guarantees for the rational development and utilization of water resources in the FMA and the sustainable development of the economy in Northeast China.

A preliminary investigation of the small rockfall triggering conditions along a road network in Slovenia

AbstractRockfalls are among the natural hazards that endanger infrastructure, cause major economic disruptions, and threaten human lives. These phenomena result from long-term geological processes such as tectonic rock deformation or weathering, but the actual rockfall itself occurs suddenly, usually without warning. The triggering mechanisms are complex and difficult to trace. In this study, we investigated the triggering mechanisms of more than 2100 small rockfalls that occurred in 2021 in Slovenia, Europe, along the 51,000 km long national road network. We analyzed their spatial and temporal characteristics, as well as the triggering mechanisms of their occurrence, based on different weather scenarios. Multiple data mining methods were used to investigate triggering conditions, and scenario analyses were used to understand the triggering mechanisms. Most small rockfalls in 2021 were recorded in winter and spring at a density of 1 rockfall per 10 km2. The results show that winter weather conditions have the greatest potential for triggering small rockfalls in Slovenia, both in terms of spatial extent and frequency of triggering weather conditions. The analysis showed that summer storms are an important but indeterminant factor for the occurrence of small rockfalls. Among the scenarios tested, the winter scenario, which includes a combination of antecedent precipitation, snowmelt, and freeze‒thaw cycles a few days before the event, was able to predict 72% of the events in the colder season.