Degree Of Weathering Research Articles

Molecular-level insight into the role of soil-derived dissolved organic matter composition in regulating photochemical reactivity

Soil-derived dissolved organic matter (DOM) links soil and water carbon pools and is an important source of photochemically produced reactive intermediates (PPRIs) in aquatic environments. Despite its importance, the variations in photochemical reactivity of soil-derived DOM molecules in producing PPRIs across broad geographical regions, and the factors driving these variations, remain unclear. Herein, we resolved the apparent quantum yields (Φ(PPRIs)) of hydroxyl radicals (•OH), singlet oxygen (1O2), and excited triplet-state DOM (3DOM*) for irradiated DOM from 22 representative soil reference materials in China, and linked them to soil pH, mineral weathering degree, and DOM characteristics. Generally, the average Φ(PPRIs) values of the soil-derived DOM followed the order of Φ(3DOM*) (1.67× 10−2) > Φ(1O2) (1.47× 10−2) > Φ(•OH) (7.31× 10−5). The DOM from less weathered soils showed higher Φ(•OH) and Φ(3DOM*) and comparable Φ(1O2) than that from more weathered soils. The differences were mainly regulated by the abundance of humic-, lignin-, tannin-, and aromatic-like compounds, as indicated by the correlation and random forest model analyses. Partial least squares and multiple linear regression analyses identified DOM molecular weight, nominal oxidation state of carbon, and soil chemical index of alteration as effective predictors of •OH yields. Soil chemical index of alteration emerged as a prioritized predictor of 3DOM* yields, while the electron-donating capacity and humic-like compound content of the soil-derived DOM were effective predictors of 1O2 yields. This study advances our understanding of how mineral weathering processes regulate the photochemical reactivity of soil-derived DOM in the aquatic environment across wide geographical regions.

GROUNDWATER MANAGEMENT: INTEGRATING GEOLOGICAL AND HYDROLOGICAL DATA FOR EFFECTIVE DECISION MAKING

The most valuable natural resource for all of humanity, not just for a state or nation, is water. A country's ability to prosper largely rests on how wisely it uses this resource. Thus, water, which flows in rivers and streams, can be said to be a nation's primary asset. This proves rivers are important, and further justification is needed to emphasise how important they are. The global acceptance of river basins as planning and management domains stems from the fact that water transcends national boundaries. India's rivers are one of its most defining characteristics; the people of India place great religious significance on them. Since groundwater is the most abundant freshwater resource, it is essential to pinpoint the groundwater potential zones for the ongoing and sustainable growth of socioeconomic and agricultural advances. Hard, fractured rock aquifers underlie most of south India's densely inhabited areas. The meagre amount of freshwater that these aquifers provide is the only source that people may use for cultivation and drinking. Because of the diverse nature of the aquifer owing to varied composition, degree of weathering, and density of fracturing, groundwater conditions in hard rock terrain are multivariate. Therefore, a thorough understanding of the distribution and features of the aquifer under the various hydrogeologic circumstances of the research region is necessary for the long-term utilisation of groundwater resources. This study's primary goal is to evaluate the possibility for groundwater management utilising hydrological and geological investigations.

Study on the Applicability of Deterioration Detection Techniques for Sandstone Heritage in Multi Environment using MLP-Attention Model

Abstract. Stone cultural heritage, encompassing a broad spectrum of artifacts such as stone artworks, buildings, tools, and utensils, represents one of the most significant categories of cultural heritage. However, the conservation of these cultural heritage faces challenges from the process of deterioration. This degradation not only compromises the structural integrity of the heritage but also results in the loss of invaluable historical information. Thus, there emerges a critical demand for effective methods to detect and assess the condition of stone cultural heritage, enabling timely and precise conservation interventions. Here we obtained sandstone samples under different deteriorative environments through laboratory-simulated deterioration experiments and employed a variety of detection technologies to capture a series of changes in the deterioration detection parameters during the sandstone deterioration process. Subsequently, a deep learning model was established to correlate the detection parameters with the degree of stone deterioration. A SHAP analysis was then conducted to determine the contribution of various parameters to the degree of stone weathering under different experimental environments, providing recommendations for selecting appropriate detection technologies and indicators adapted to different deterioration environments. To further analyze the deterioration processes of the stone samples, XRD analysis was conducted to observe changes in mineral composition throughout the deterioration process. SEM images were utilized to examine the changes in micro-morphology and the internal pore structure associated with deterioration. This study provides a basis for the scientific design of deterioration detection schemes by selecting the most suitable testing technology for optimal deterioration assessment under specific environmental conditions.

Study on infrared thermal imaging for surface deterioration investigation and evaluation of stone cultural relics based on temperature variation

This study leverages infrared thermal imaging technology to advance the field of stone cultural relics preservation by introducing a novel evaluation index—temperature variation (Tv)—that quantifies the degree of surface deterioration. Unlike previous studies that have focused primarily on detecting a single deterioration type, this study pioneered a comprehensive analysis of the interactions of multiple deterioration in stone cultural relic. A deeper understanding of the weathering mechanisms of stone cultural relics has been gained by examining the Tv on the surface of stone cultural relics during heating and cooling, and successfully relating these changes to the degree of weathering of the cultural relic. This study developed a linear fitting method for systematically assessing the degree of weathering of stone cultural relic, which is a significant improvement over traditional assessment techniques. Our approach not only enhances the accuracy and applicability of Tv as an evaluation index but also integrates environmental temperature considerations, ensuring a more reliable assessment under varying conditions. The study's findings validate the effectiveness of infrared thermal imaging in identifying deterioration types and evaluating their severity, setting a new standard for the protection and restoration of stone cultural relics.

Generation and geochemical characteristics of acid rock drainage (ARD) in Barton Peninsula, King George Island (KGI), maritime, Antarctica

This study deals with the generation, geochemical characteristics, and environmental impacts of acid rock drainage (ARD), a global environmental problem, on the Barton Peninsula. To elucidate the governing processes and to assess the environmental hazards of ARD, we present chemical data from lakes, ponds, and creeks with a wide range of pH values. We also provide mineralogical and geochemical compositions of sediments and bedrocks. Compared to weak-acidic and neutral waters, waters that display typical characteristics of ARD with low pH (3.7 to 4.2), high sulfate (46 to 92 mg/L), and Fe (0.8 to 16.5 mg/L) occur in the northern tip of the peninsula. Acidic waters with the highest cation (e.g., K, Na, Si, and Ca) and anion (e.g., SO4) compositions indicate ARD-enhanced rock weathering in the peninsula. Consistently, quantifying of chemical weathering degree yields the highest chemical index of alteration (CIA) and the mafic index of alteration (MIA) with the lowest ICV values for sediments from the acidic waters. Enrichment factors (EFs) calculated for As, Co, Cd, Cu, Pb, Zn, and Ni indicate severe to minor enrichment for As and Pb metals, respectively in the acidic water-associated sediments. Heavy metal concentrations of acidic waters also display the highest values for the peninsula, with Fe, Cu, and Cd metals exceeding the chronic aquatic toxicity limit (CAT). Therefore, geochemical records of acidic waters and sediments, especially lakes, may help in tracing the long-term environmental impacts of ARD, while sediments obtained from the weak acidic and near-neutral waters, together with water chemistry data, may provide a better representative composition of the bedrocks with neutralizing potential. The data presented here may contribute to predicting the source/s, and extent of future ARD generation in the peninsula, which is likely to be enhanced by increased chemical weathering due to climate warming.

Physical–Chemical and Thermal Properties of Clays from Porto Santo Island, Portugal

The use of clays for thermal treatments and cosmetic purposes continues to be a worldwide practice, whether through the preservation of native cultural traditions, pharmaceutical formulations or integrative health and well-being practices. Special clays, such as bentonites, are very common for healing applications due to their high cation exchange capacity (CEC), high specific surface area (SSA) and alkaline pH values and, therefore, are used in multiple therapeutic and dermocosmetic treatments. Numerous bentonitic deposits occur on Porto Santo Island with different chemical weathering degrees. This research evaluates which residual soils have the most suitable characteristics for pelotherapy. The texture of residual soils varies from silt loam to loamy sand and SSA between 39 and 90 m2/g. The pH is alkaline (8.7 to 9.6), electrical conductivity ranges from 242 to 972 µS/cm, and CEC from 50.4 to 86.8 µS/cm. The residual soils have a siliciclastic composition (41.36 to 54.02% SiO2), between 12.52 and 17.65% Al2O3 and between 52 and 82% smectite content, which are montmorillonite and nontronite. Specific heat capacity (0.5–0.9 J/g°C) and cooling kinetics (14.5–19 min) show that one residual soil has the potential to be suitable for pelotherapy according to the literature. Moreover, the residual soils have As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and V concentrations higher than the limits of guidelines for cosmetics and pharmaceutical products.

Sedimentary phosphorus sequential extraction method offers new insight into soil development

Fractionation of soil phosphorus (P) by sequential extraction is one of tools to study the soil development in Earth’s critical zone for characterization of weathering pattern and soil evolution. A sequential extraction method originally developed for sediment with advantage of separating CaCO3-bound P from igneous fluorapatite has been used to quantify different forms of P in New England native forest soils. Total soil phosphorus is fractionated into exchangeable, iron-bound, CaCO3-bound, igneous fluorapatite and refractory organic P pools. Seven surface soil samples were collected from coastal, terrestrial, and lacustrine environments. Total P (TP) ranges from 11.4 to 21.5 μmol P g-1. Averaging over all sampling locations, the largest fraction is igneous fluorapatite with an average concentration of 4.9 ± 1.6 μmol P g-1, accounting for 29.2 ± 9.5 % of TP. Refractory organic P is the second largest fraction with an average concentration of 4.4 ± 1.6 μmol P g-1, accounting for 27.0 ± 9.6 % of TP. Iron-bound P is the third largest fraction with an average concentration of 3.3 ± 1.7 μmol P g-1, accounting for 20.3 ± 10.0 % of TP. CaCO3 -bound P is the second smallest fraction with an average concentration of 2.8 ± 1.4 μmol P g-1, accounting for 16.3 ± 7.5 % of TP. As usual, the smallest fraction is exchangeable P with an average concentration of 1.2 ± 0.8 μmol P g-1, accounting for 7.2 ± 4.3 % of TP. Data from this study are well fitted to a linear model based on the previous sequential extraction data compiled from global soils and sediments samples. The sequential extraction method used here offers an improved procedure that quantify the abundance of igneous fluorapatite as primary P mineral, which provides an estimate of the state and degree of weathering and soil development in the region.

Nitrogen in the Orgueil meteorite: Abundant ammonium among other reservoirs of variable isotopic compositions

Nitrogen, because of its abundance and variety of carrier phases, is a unique tracer of physico-chemical processes occurring throughout star and planet formations. The refractory organic matter is commonly considered as the main carrier of nitrogen in the most primitive objects of our Solar System. However, nitrogen in the form of ammonium (NH4+) was observed in the Ivuna-type carbonaceous (CI) chondrites Alais in 1834, and Orgueil just after its fall in 1864, as well as more recently on Ceres, comet 67P/Churyumov-Gerasimenko, and possibly on some asteroids. In the present study, we have measured the nitrogen content and isotopic composition in various nitrogen-bearing phases of several samples of the Orgueil meteorite, with different degrees of terrestrial weathering. Water-soluble NH4+ is present in Orgueil at a mean concentration of 0.07 ± 0.01 wt%, with a mean isotopic composition of δ15N = +72 ± 9 ‰ (14N/15N = 254 ± 2), confirming its extra-terrestrial origin. In the most terrestrially altered sample of Orgueil that we analysed, the isotopic composition is δ15N = +50 ± 12 ‰ (14N/15N = 259 ± 3). NH4+ is in species that are thermally stable up to 383 K, possibly ammonium inorganic/organic salts and ammoniated phyllosilicates. We also show that the nitrogen in Orgueil is distributed among the insoluble organic matter (IOM) (35 ± 5 %), ammonium (27 ± 5 %), and other minor water-soluble species (e.g., nitrate, amines etc.: < 6 %). The remaining nitrogen (34 ± 14 %) is mainly in an unidentified organic matter (UOM), which may be IOM lost during its extraction and/or acid hydrolysable functional groups bounded to the IOM and/or organic nitrogen trapped within minerals. The three main carriers of nitrogen in Orgueil have δ15N (and 14N/15N) values of + 32 ± 1 ‰ (264 ± 0.3) for IOM, +39 ± 16 ‰ (262 ± 4) for UOM, and + 72 ± 9 ‰ (254 ± 2) for NH4+.Although IOM and NH4+ have significantly different δ15N, we cannot exclude that these phases could be compositionally related because IOM is heterogeneous in 15N. Ammonium could have been produced via heating and/or aqueous alteration processes of organic matter in the CI parent body. Alternatively, or additionnally, ammonium could be a tracer of the accretion and/or later deposit of NH3 ice, NH3 hydrates, and/or NH4+ salts on the CI parent body.As shown by previous studies, Ryugu grains sampled by the Hayabusa2 mission (JAXA) have heterogeneous compositions at the millimeter scale, with nitrogen concentrations and δ15N similar or lower than Orgueil, possibly because of different parent body processing. The present study suggests that the lack or loss of 15N-rich NH4+ in some Ryugu grains may explain some of these differences with Orgueil.

Effect of In Situ Polymerization of Super Absorbent Polymers on the Protection of Earthen Heritage Sites in Semi-Arid Regions

As precious cultural heritage, earthen sites are susceptible to various natural factors, leading to diverse forms of degradation. To protect earthen sites, the effects of super absorbent polymers (SAPs) on soil water retention, physical properties, and color compatibility at different concentrations were studied. After applying SAP treatment to an earthen site with different degrees of weathering, we drew the following conclusions. SAP-2 improved soil water retention capacity, increased soil water content, and slowed down the precipitation of soluble salts. At the same time, SAP-2 had the least effect on soil color difference and reduced the development of cracks by filling soil pores and enhancing the cohesion between soil particles, thus giving the earthen sites better weathering resistance. Therefore, the results provide a useful reference for the surface cracking of earthen sites in semi-arid areas and the degradation caused by flaking and block spalling.

Provenance, paleoweathering, sediment maturity, and depositional environment of intertrappean sediments in Angot–Gazo volcanic plateau, northeastern Ethiopia: Evidence from field mapping, petrography and geochemistry

Numerous intertrappean beds have been reported in different sections of the Ethiopian highlands; however, their detailed paleo-sedimentological characteristics have not been fully examined. This study investigates the source rock composition, tectonic setting, degree of past weathering, paleoclimatic conditions, sediment maturity, and depositional environments of the Angot–Gazo terrestrial sediments through geological mapping, mineralogical analysis, and geochemical approaches. Two terrestrial beds, consisting of mudrock and sandstone, were identified. The sandstone is characterized by massive, medium to coarse, and poorly sorted grains that range from sub-rounded to angular shapes. Minerallogically, the sandstone comprises quartz, feldspar, and lithic fragments grains with a proportional amounts of ash material. Both mineralogical (Q–F–R) and geochemical classification plots categorize the sandstone as arkosic to lithic greywacke. Felsic volcanic rocks are the main source material for the investigated sediments, as evidenced by multiple discrimination plots (DF1 vs. DF2, V–Ni–Th∗10, La–Th–Sc, Cr/Th–Th/Sc, La/Co–Th/Co, La/Sc–Th/Co and Y/Ni–Cr/V), LREE/HREE patterns, elemental ratios, and the appearance of abundant felsic-derived lithic fragments within the sandstone. A new bivariate discriminant function plot from DF1 vs. DF2 analysis, coupled with ternary diagrams of Zr/10–Th–Sc for the studied intertrappean sediments, revealed a continental rift setting, particularly a passive continental margin. Ternary diagram of A–CN–K, binary plots of Al₂O₃/Na₂O vs. average values of weathering indices (CIA, CIW, PIA, & MIA), and SiO2 vs. Al2O3+K2O + Na2O plot demonstrate slight to moderate degree of weathering for the sandstone, and deep weathering for the mudrock under semi-arid paleoclimatic conditions. The binary schemes of SiO2/Al2O3 and Ni–TiO2 ratio, along with the significant abundance of angular to sub-angular framework grains, reflect both immaturity and initial sediment recycling. Finally, the examined sediments were deposited in freshwater under oxic conditions, as evidenced by binary plots of Sr/Ba, Th/U, U/Th, and Ni/Co.

Effects of microplastic interaction with persistent organic pollutants on the activity of the aryl hydrocarbon and estrogen receptors

Environmental microplastics (MPs) are complex mixtures of plastic polymers and sorbed chemical pollutants with high degrees of heterogeneity, particularly in terms of particle size, morphology and degree of weathering. Currently, limitations exist in sampling sufficient amounts of environmental particles for laboratory studies to assess toxicity endpoints with statistical rigor and to examine chemical pollutant interactions. This study seeks to bridge this gap by investigating environmental plastic particle mimetics and pollutant-polymer interactions by mixing polymer particles with persistent organic pollutants (POPs) at set concentrations over time. Solutions containing combinations of polymers including polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), and polyamide (PA) and POPs including 2,3,7,8 -Tetrachlorodibenzo-p-dioxin (TCDD), bisphenol A (BPA), and atrazine, were stirred for up to 19 weeks and monitored using assays to test for aryl hydrocarbon (AhR) and estrogen receptor (ER) activity which are cell signaling pathways impacted by environmental pollutants. TCDD induced AhR activity decreased over time in the presence of PS in a surface area dependent manner. BPA and atrazine also exhibited AhR antagonist activity in the presence of TCDD. The addition of BPA slowed the loss of activity but atrazine did not, suggesting that polymer chemistry impacts interactions with POPs. We also observed potential differences in TCDD sorption with different plastic polymers and that higher concentrations of PS particles may inhibit BPA-induced estrogen receptor activation. These results emphasize the need for additional understanding of how POPs and polymer chemistry impact their interaction and toxicity.

Physical and Geochemical Characterisation of Pongo Pitti and Bossambo Farm Clays (Littoral Region, Cameroon) for use in Ceramics

The main objective of this work is to discern the physico-chemical and mechanical behavior of the Pongo Pitti and Bossambo Farm clay formations, located on either side of the Sanaga river in the littoral region of Cameroon. To achieve this, two field campaigns and laboratory works were carried out. Four clay materials were collected and brought back to the laboratory. The laboratory investigations involved physico-mechanical and geochemical analyses, followed by ceramic testing. The materials studied have a clayey texture, with clay percentages ranging from 26.89% to 80.3%, silt from 13.2% to 57.6% and sand from 1.58% to 47.26%. The plasticity index ranges from 11.9% to 24.2%. From a geochemical standpoint, the materials studied show a predominance of silica (49.6% to 63.5%), alumina (20.5% to 27.1%) and iron (2.39% to 8.6%), with the SiO2/Al2O3 ratio varying from 1.96 to 3.1. The Al2O3/Fe2O3 ratio is 8.4 for Pongo Pitti clays and 2.9 for Bossambo Farm clays. The geochemical weathering indices (ICV, CIA, PIA, CIW, CIW) show a high degree of weathering, with values in excess of 90%. Alkali and alkaline-earth proportions are lower, and the K2O/Na2O ratio varies between 8.45 and 14.24, showing an enrichment of potassium in relation to sodium. Lantane is the most abundant rare-earth element (323.84 ppm). The REE study shows a predominance of light REEs over heavy REEs (LREE/HREE~4.51) and a negative Europium anomaly. Infrared spectroscopy showed poor kaolinite crystallinity. Mechanically, the specimens studied, fired at temperatures ranging from 950℃ to 1050℃ showed good cohesion and metallic soundness. Linear shrinkage was 4.8%. Mass loss increases with temperature. Its value is 12.5% for Pongo Pitti materials and 8.5% for Bossambo Farm materials. Water absorption decreases with temperature and is 20.27% for Pongo Pitti samples and 15.79% for Bossambo Farm samples. Bulk density increases with temperature (2.11 at 950℃ to 2.51 at 1050℃). Flexural strength increases with temperature and is 6.66 MPa for materials from Pongo Pitti and 8.89 MPa for those from Bossambo Farm. These materials can be used to make fired bricks and roof tiles, and Pongo Pitti materials can be used to make refractory ceramics

Quantifying the effects of carborundum rock surface smoothing for Schmidt hammer R‐value metrics measured on glacial erratics in the North American Great Lakes region

AbstractSchmidt hammer R‐values, which reflect the degree of rock surface weathering, can be paired with independent rock surface exposure ages to produce Schmidt hammer exposure‐age dating (SHD) calibration curves that are used to provide rapid estimations of exposure ages for undated rock surfaces. In this Letter, we lay the groundwork for later establishing a SHD calibration curve based on glacial erratics deposited by the Laurentide Ice Sheet in the North American Great Lakes region. First, we establish a reference R‐value for a calibration boulder, which may be used to facilitate direct comparison of R‐values collected by different individuals using mechanical N‐type Schmidt hammers, specifically. We then assess how no, light or heavy use of a carborundum puck to smooth rock surfaces affects resulting R‐value data. Lastly, we compare two different R‐value metrics on the same rock surface: Rmean (n = 30) versus ΔR (Rmax − Rmin of five consecutive R‐values on the same spot). In all assessments, Rmean is similar for erratic surfaces with no and light surface treatment, and both are significantly lower than Rmean of surfaces with heavy treatment. Thus, we advise against the use of heavy surface treatment in SHD applications. We observe no relationship between inferred erratic age and either Rmean or ΔR, which could arise from inferred ages of erratics being inaccurate, from inferred ages of erratics being too similar or from measuring too few erratics from each landform.

Geochemical Characterization and Constraints on Provenance, Tectonic setting and Paleoweathering of the Miocene Bhuban Sandstone Exposed in Sakhan Anticline, Tripura Fold Belt, Surma Basin, India

ABSTRACT The petrography of sandstone, major oxides, trace and REE compositions of the Bhuban formation, exposed in the Sakhan Anticline of Tripura Frontal Fold Belt have been studied to determine the source rock, depositional tectonic setup and paleoweathering conditions. The average modal composition of the Bhuban Sandstone (Q89.27F4.40L6.33) classified them as quartz arenite and sub litharenite types. The modal composition data (Q-F-L) indicates a craton interior and recycled source for these sediments and deposited in an active continental basin margin as suggested by the bivariate plot of SiO2 vs. K2O/Na2O. The binary discrimination plot of Hf vs. La/Th suggests acidic and older sedimentary component as source for the studied sandstone. The ternary plot of V-Ni-Th×10 pointed towards felsic igneous provenance. Trace and rare earth elemental ratios, chondrite-normalize REE plot suggests the source of the Bhuban sediments are derived from felsic terrain. The CIA values (66.48-75.41), A-CN-K plot (A=Al2O3, CN=CaO+ Na2O, K=K2O) and distinct depletion of Na2O, CaO, U, Sr and Ba suggests moderate degree of chemical weathering of the source rocks which may indicate humid climatic conditions in the source area.

Soil hydraulic properties, mineralogical alteration and pore formation in Regosols from southern Brazil

ABSTRACT Regosols (Neossolos) are soils with use limitations mainly related to effective depth, abundant presence of rock and saprolite fragments, and frequently high slope gradients; besides that, they represent a new agricultural frontier for grain production in southern Brazil. This study evaluated soil saturated hydraulic conductivity (K sat ) and water retention and availability in Regosols and saprolites derived from volcanic rocks in southern Brazil and the relationship of these variables with porosity in saprolithic horizons characterized by mineralogical weathering. The study was carried out on eight profiles derived from basic and acidic volcanic rocks of the Serra Geral Formation. We evaluated soil morphology, granulometry, porosity, bulk density (BD), K sat , water retention, electronic/ optical microscopy and chemical composition of parent materials, and soil mineralogy. Soil K sat ranged from 0.0 to 6.40 cm h -1 in the evaluated horizons, without significant difference between the A and Cr horizons. Seven soil profiles showed BD equal to or less than 1.28 Mg m -3 for the Cr samples. Total porosity in the Cr horizons was above 0.5 m 3 m -3 and not significantly different from A horizons. In five of the eight soil profiles, one or more Cr horizons presented greater available water than A horizons. Electronic and optical microscopy evidenced abundant cracks and mineralogical weathering in the rock samples. X-rays diffraction data also indicated advanced degree of weathering of Cr horizons, evidencing abundant formation of pores in the saprolite. and justifying the high-water retention in Regosols profiles in southern Brazil.

Toxicity of the oil spilled on the Brazilian coast at different degrees of natural weathering to early life stages of the zebrafish Danio rerio

Toxicity of water accommodated fractions (WAF) from the oil spilled on the Brazilian coast at different stages of weathering were investigated using Danio rerio. Weathering stages included emulsified oil that reached the coast (OM) and oil collected 50 days later deposited on beach sand (OS) or adhered to shore rocks (OR). Parent and alkylated naphthalenes decreased whereas phenanthrenes increased from less weathered WAF-OM to more weathered WAF-OS and WAF-OR. More weathered WAF-OS and WAF-OR were more potent inducers of zebrafish developmental delay, suggesting that parent and alkylated phenanthrenes are involved. However, less weathered WAF-OM was a more potent inducer of failure in swim-bladder inflation than more weathered WAF-OS and WAF-OR, suggesting that parent and alkylated naphthalenes are involved. Decreases in heart rates and increased heart and skeletal deformities were observed in exposed larvae. Lowest observed effect concentrations for different developmental toxicity endpoints are within environmentally relevant polycyclic aromatic hydrocarbon concentrations.

Geochemistry of Quaternary sediments in the northwestern South China Sea: Sediment provenance and mid-Pleistocene transition

The Quaternary sediments in the northwestern South China Sea (NW-SCS) provide valuable information about provenance, climate and sea level changes. However, the correlation between the geochemical records in marine sediments and these influencing factors remains less understood in the NW-SCS. Two wells penetrated Quaternary sediments on the shelf and shelf margin of the NW-SCS and provide an excellent dataset. In this study, the major, trace, and rare earth elements in the sediments were analyzed to reveal the Quaternary provenance changes that correlate with the climatic Middle Pleistocene transition (MPT). These results indicate that the core sediments were mainly derived from felsic source rocks and the degree of chemical weathering in the source areas is relatively low (CIA averaged at 58). The Quaternary provenance of the NW-SCS did not undergo significant changes, recording mixed sedimentation from the Red River, Hainan Island, and central Vietnamese sources. The felsic source rocks and negative Eu anomaly indicated the shelf area received sediments primarily from the Red River and Hainan Island. However, a positive Eu anomaly on the shelf margin suggests additional contributions from mafic rocks sourced from central Vietnam. During the MPT (1.3–1.4 to 0.8–0.9 Ma), the dominant periodicity of climate cycles changed from a 40 kyr obliquity cycle to a 100 kyr eccentricity cycle; the cooling climate led to a slight weaking in chemical weathering and a minor decrease in sediment supply from terrestrial sources. After the MPT, the mixed sourced sediments in the shelf and shelf margin areas of the NW-SCS likely suffered from multiple hydrodynamic forces under the influence of the Pleistocene high-frequency and high-amplitude sea level fluctuations. These climate induced changes led to significant fluctuations in element content that provide new insights into Quaternary sources and climatic events in the NW-SCS.

Role of Source, Mineralogy, and Organic Complexation on Lability and Fe Isotopic Composition of Terrestrial Fe sources to the Gulf of Alaska.

Iron (Fe) is a key trace nutrient supporting marine primary production, and its deposition in the surface ocean can impact multiple biogeochemical cycles. Understanding Fe cycling in the subarctic is key for tracking the fate of particulate-bound sources of oceans in a changing climate. Recently, Fe isotope ratios have been proposed as a potential tool to trace sources of Fe to the marine environment. Here, we investigate the Fe isotopic composition of terrestrial sources of Fe including glacial sediment, loess, volcanic ash, and wildfire aerosols, all from Alaska. Results show that the δ56Fe values of glaciofluvial silt, glacial dissolved load, volcanic ash, and wildfire aerosols fall in a restricted range of δ56Fe values from -0.02 to +0.12‰, in contrast to the broader range of Fe isotopic compositions observed in loess, -0.50 to +0.13‰. The Fe isotopic composition of the dissolved load of glacial meltwater was consistently lighter compared to its particulate counterpart. The 'aging' (exposure to environmental conditions) of volcanic ash did not significantly fractionate the Fe isotopic composition. The Fe isotopic composition of wildfire aerosols collected during an active fire season in Alaska in the summer of 2019 was not significantly fractionated from those of the average upper continental crust composition. We find that the δ56Fe values of loess (<5 μm fraction) were more negative (-0.32 to +0.05‰) with respect to all samples measured here, had the highest proportion of easily reducible Fe (5.9-59.6%), and were correlated with the degree of chemical weathering and organic matter content. Transmission electron spectroscopy measurements indicate an accumulation of amorphous Fe phases in the loess. Our results indicate that Fe isotopes can be related to Fe lability when in the presence of organic matter and that higher organic matter content is associated with a distinctly more negative Fe isotope signature likely due to Fe-organic complexation.

Tectonic Geomorphology of Ultramafic Complex in Asera, North Konawe Regency

Ultramafic complex in Sulawesi have many potential from mining to environmental aspects. The process of weathering and tectonic is a key factor in understanding how to utilize these potential. Tectonic geomorphology by using morphometric indices and field observation has proven to be a beneficial method in distinguishing the topography and morphogenetic development of a region due to the complex interaction between erosional processes and tectonic movements. IAT measurement of 71 sub-basins shows that tectonic activity in the research area are divided into 4 classes with values ranging from 1,5 – 2,6. Field observation shows that morphologically the research area are faulted hills consist of peridotite, dunite and pyroxenite with various degree of weathering. The effect of weathering also reveal on the shape of sub-basins and drainage density in the research area. Tectonic activity present in the form of intensive joint on some parts, with no clear correlation with IAT Class. keyword: tectonic geomorphology, carbon capture storage, ultramafic, east Sulawesi ophiolite, morphometric indices

Binding between Cu2+/Zn2+ and aged polyethylene and polyethylene terephthalate microplastics in swine wastewaters: Adsorption behavior, and mechanism insights

Microplastics (MPs) have aroused growing environmental concerns due to their biotoxicity and vital roles in accelerating the spread of toxic elements. Illuminating the interactions between MPs and heavy metals (HMs) is crucial for understanding the transport and fate of HM-loaded MPs in specific environmentally relevant scenarios. Herein, the adsorption of copper (Cu2+) and zinc (Zn2+) ions over polyethylene (PE) and polyethylene terephthalate (PET) particulates before and after heat persulfate oxidation (HPO) treatment was comprehensively evaluated in simulated and real swine wastewaters. The effects of intrinsic properties (i.e., degree of weathering, size, type) of MPs and environmental factors (i.e., pH, ionic strength, and co-occurring species) on adsorption were investigated thoroughly. It was observed that HPO treatment expedites the fragmentation of pristine MPs, and renders MPs with a variety of oxygen-rich functional groups, which are likely to act as new active sites for binding both HMs. The adsorption of both HMs is pH- and ionic strength-dependent at a pH of 4–6. Co-occurring species such as humic acid (HA) and tetracycline (TC) appear to enhance the affinity of both aged MPs for Cu2+ and Zn2+ ions via bridging complexation. However, co-occurring nutrient species (e.g., phosphate and ammonia) demonstrate different impacts on the adsorption, improving uptake of Cu2+ by precipitation while lowering affinity for Zn2+ owing to the formation of soluble zinc-ammonia complex. Spectroscopic analysis indicates that the dominant adsorption mechanism mainly involves electrostatic interactions and surface complexation. These findings provided fundamental insights into the interactions between aged MPs and HMs in swine wastewaters and might be extended to other nutrient-rich wastewaters.