A simple protocol for estimating the acute toxicity of unresolved polar compounds from field-weathered oils.

Crude oil spilled at sea is chemically altered through environmental processes such as dissolution, biodegradation, and photodegradation. Transformation of hydrocarbons to oxygenated species increases water-solubility. Metabolites and oxidation products largely remain uncharacterized by common analytical methods but may be more bioavailable to aquatic organisms. Studies have shown that unresolved (i.e. unidentified) polar compounds ('UPCs') may constitute > 90% of the water-accommodated fraction (WAF) of heavily weathered crude oils, but still there is a paucity of information characterizing their toxicological significance in relation to other oil-derived toxicants. In this study, low-energy WAFs (no droplets) were generated from two field-weathered oils (collected during the 2010 Deepwater Horizon incident) and their polar fractions were isolated through fractionation. To allow establishment of thresholds for acute toxicity (LC50) of the dissolved and polar fraction of field collected oils, we concentrated both WAFs and polar fractions to beyond field-documented concentrations, and the acute toxicity of both to the marine copepod Acartia tonsa was measured and compared to the toxicity of the native WAF (non-concentrated). The difference in toxic units (TUs) between the total of the mixture and of identified compounds of known toxicity (polycyclic aromatic hydrocarbons [PAHs] and alkyl phenols) in both WAF and polar fractions was used to estimate the contribution of the UPC to overall toxicity. This approach identified that UPC had a similar contribution to toxicity as identified compounds within the WAFs of the field-weathered oils. This signifies the relative importance of polar compounds when assessing environmental impacts of spilled and weathered oil.

Ecotoxic effect in Allium cepa due to sphalerite weathering arising in calcareous conditions.

The ecotoxic effect of Zn species arising from the weathering of the marmatite-like sphalerite ((Fe, Zn)S) in Allium cepa systems was herein evaluated in calcareous soils and connected with its sulfide oxidation mechanism to determine the chemical speciation responsible of this outcome. Mineralogical analyses (X-ray diffraction patterns, Raman spectroscopy, scanning electron microscopy and atomic force microscopy), chemical study of leachates (total Fe, Zn, Cd, oxidation-reduction potential, pH, sulfates and total alkalinity) and electrochemical assessments (chronoamperometry, chronopotentiometry, cyclic voltammetry, and electrochemical impedance spectroscopy) were carried out using (Fe, Zn)S samples to elucidate interfacial mechanisms simulating calcareous soil conditions. Results indicate the formation of polysulfides (Sn2-), elemental sulfur (S0), siderite (FeCO3)-like, hematite (Fe2O3)-like with sorbed CO32- species, gunningite (ZnSO4·H2O)-like phase and smithsonite (ZnCO3)-like compounds in altered surface under calcareous conditions. However, the generation of gunningite (ZnSO4·H2O)-like phase was predominant bulk-solution system. Quantification of damage rates ranges from 75 to 90% of bulb cells under non-carbonated conditions after 15-30 days, while 50-75% of damage level is determined under neutral-alkaline carbonated conditions. Damage ratios are 70.08 and 30.26 at the highest level, respectively. These findings revealed lower ecotoxic damage due to ZnCO3-like precipitation, indicating the effect of carbonates on Zn compounds during vegetable up-taking (exposure). Other environmental suggestions of the (Fe, Zn)S weathering and ecotoxic effects under calcareous soil conditions are discussed.

Characterization and mechanical removal of metallic aluminum (Al) embedded in weathered municipal solid waste incineration (MSWI) bottom ash for application as supplementary cementitious material.

Municipal solid waste incineration (MSWI) bottom ash, due to its high mineral content, presents great potential as supplementary cementitious material (SCM). Weathering, also known as aging, is a treatment process commonly employed in waste management to minimize the risk of heavy metal leaching from MSWI bottom ash. Using weathered MSWI bottom ash to produce blended cement pastes is considered as a high-value-added and sustainable waste disposal solution. However, a critical challenge arises from the metallic aluminum (Al) in weathered MSWI bottom ash, which is known to induce detrimental effects such as volume expansion and strength loss of blended cement pastes. While most metallic Al in weathered MSWI bottom ash can be removed with eddy current separators in metal recovery plants, the residual metallic Al, owing to its small particle size, cannot be removed with the same technique. This study is dedicated to addressing this issue. An in-depth analysis was conducted on residual metallic Al embedded in weathered MSWI bottom ash particles, aiming to guide the removal of this metal. This analysis revealed that mechanical removal was the most suitable method for extracting metallic Al. The specific processes and mechanisms underlying this method were elucidated. After reducing metallic Al content in weathered MSWI bottom ash by 77 %, a significant improvement in the quality of blended cement pastes was observed. This work contributes to the broader adoption of mechanical treatments for removing residual metallic Al from weathered MSWI bottom ash and facilitates the application of treated ash as SCM.

Pretty in pink? Complementary strategies for analysing pink biofilms on historical buildings.

Salt-weathering is a deterioration mechanism affecting building materials that results from repetitive cycles of salt crystallisation-dissolution in the porous mineral network under changing environmental conditions, causing damage to surfaces. However, an additional biodeterioration phenomenon frequently associated with salt efflorescence is the appearance of coloured biofilms, comprising halotolerant/halophilic microorganisms, containing carotenoid pigments that cause pinkish patinas. In this work, two Austrian historical salt-weathered buildings showing pink biofilms, the St. Virgil's Chapel and the Charterhouse Mauerbach, were investigated. Substrate chemistry (salt concentration/composition) was analysed by ion chromatography and X-ray diffraction to correlate these parameters with the associated microorganisms. Microbiomes were analysed by sequencing full-length 16S rRNA amplicons using Nanopore technology. Data demonstrates that microbiomes are not only influenced by salt concentration, but also by its chemical composition. The chapel showed a high overall halite (NaCl) concentration, but the factor influencing the microbiome was the presence/absence of K+. The K+ areas showed a dominance of Aliifodinibius and Salinisphaera species, capable of tolerating high salt concentrations through the "salt-in" strategy by transporting K+ into cells. Conversely, areas without K+ showed a community shift towards Halomonas species, which favour the synthesis of compatible solutes for salt tolerance. In the charterhouse, the main salts were sulphates. In areas with low concentrations, Rubrobacter species dominated, while in areas with high concentrations, Haloechinothrix species did. Among archaea, Haloccoccus species were dominant in all samples, except at high sulphate concentrations, where Halalkalicoccus prevailed. Finally, the biological pigments visible in both buildings were analysed by Raman spectroscopy, showing the same spectra in all areas investigated, regardless of the building and the microbiomes, demonstrating the presence of carotenoids in the pink biofilms. Comprehensive information on the factors affecting the microbiome associated with salt-weathered buildings should provide the basis for selecting the most appropriate desalination treatment to remove both salt efflorescence and associated biofilms.

How weathering might intensify the toxicity of spilled crude oil in marine environments.

Crude oils are highly complex mixtures containing many toxic compounds for organisms. While their level of toxicity in a marine environment depends on many parameters, one of the main factors is their composition. After oil spills, their compositions are significantly changed, so it changes the toxicity. In this study, different weathering processes such as evaporation, photooxidation, and biodegradation were applied to crude oil to understand how composition changed over time and how this affects its toxicity on phytoplankton. In laboratory settings, three distinct water-accommodated fraction samples of crude oil were prepared, unweathered, evaporated, and weathered and were exposed to phytoplankton communities at different dilution levels. After 3 days, evaporation reduced the crude oil concentration by 47%, and the concentration of the crude oil affected by photooxidation, biodegradation, and evaporation reduced by 81%. This study also showed that even though the weathering reduced the overall amount of crude oil substantially, its toxicity increased significantly. In the microcosm experiments, 7-day EC50 values of the unweathered oil, the evaporated oil and the weathered oil were 49.07, 21.09, and 7.16 µg/L, respectively. Different processes altered the crude oil composition, and weathered crude oil ended up with a higher fraction of high molecular weight (HMW) polycyclic aromatic hydrocarbons (PAHs). A promising relation between the increasing toxicity and HMW PAH fraction indicates that increasing the fraction of HMW PAHs might be one of the main reasons for the weathering process to cause higher crude oil toxicity. These results could be used as a diagnostic tool to estimate the extent of weathering and toxicity of crude oil after spills.

Pathways and processes to the embodiment of historical trauma secondary to settler colonialism.

AIM(S): This discursive article aims to examine how systemic factors of settler colonialism influence health outcomes among Indigenous peoples in the United States through pathways and processes that may lead to the embodiment of historical trauma. DESIGN: Discursive paper. METHODS: We completed a comprehensive search of empirical and grey literature between September 2022 and January 2023 in PubMed, CINAHL and Google Scholar. Using these articles as a foundation, we explored factors related to the pathways and processes leading to the embodiment of historical trauma rooted in settler colonialism. RESULTS: A conceptual framework of the pathways and processes of the embodiment of historical trauma secondary to settler colonialism was developed, and is presented. CONCLUSION: The societal and historical context for Indigenous peoples includes harmful settler colonial structures and ideologies, resulting in stressors and historical trauma that impact health outcomes and disparities through the phenomenon of the process of embodiment. IMPLICATIONS FOR NURSING: To provide holistic nursing care, nurses must be aware of settler colonialism as a determinant of health. They must be attuned to the pathways and processes through which settler colonial exposures may impact health among Indigenous peoples. Nurses must challenge existing structural inequities to advance health equity and social justice.

The long-term fate of saturates and biomarkers within crude oil spilled during the Baffin Island Oil Spill (BIOS) Project.

The Baffin Island Oil Spill (BIOS) Project is a long-term monitoring field study conducted in the early 1980s, seeking to examine the physical and chemical fate of crude oil released into a pristine Arctic setting. During the present study, sites of the BIOS Project were revisited in 2019 for the collection of oiled intertidal and backshore sediments. These samples were analyzed for several groups of petroleum hydrocarbons including saturates (n-alkanes, branched alkanes, and alkylcycloalkanes), hopane and sterane biomarkers, and alkylbenzenes. These hydrocarbon groups were present in concentrations ranging from 1.77-1210, 0.224-51.7, 0.0643-16.9, 0.00-11.7, and 0.0171-8.60 mg/kg within individual samples, respectively. When comparing current to limited results from past BIOS studies, a representative branched alkane (phytane), and medium-chain (nC18) and long-chain (nC30) n-alkanes demonstrate extensive weathering processes, exhibiting up to 90 %, 98 %, and 77 % loss since the penultimate BIOS revisitation in 2001, respectively.

Hot and Cold: Photochemical Weathering Mediates Oil Properties and Fate Differently Depending on Seawater Temperature.

Photochemical weathering transforms petroleum oil and changes its bulk physical properties, as well as its partitioning into seawater. This transformation process is likely to occur in a cold water marine oil spill, but little is known about the behavior of photochemically weathered oil in cold water. We quantified the effect of photochemical weathering on oil properties and partitioning across temperatures. Compared to weathering in the dark, photochemical weathering increases oil viscosity and water-soluble content, decreases oil-seawater interfacial tension, and slightly increases density. Many of these photochemical changes are much larger than changes caused by evaporative weathering. Further, the viscosity and water-soluble content of photochemically weathered oil are more temperature-sensitive compared to evaporatively weathered oil, which changes the importance of key fate processes in warm versus cold environments. Compared to at 30 °C, photochemically weathered oil at 5 °C would have a 16× higher viscosity and a 7× lower water-soluble content, resulting in lower entrainment and dissolution. Collectively, the physical properties and thus fate of photochemically weathered oil in a cold water spill may be substantially different from those in a warm water spill. These differences could affect the choice of oil spill response options in cold, high-light environments.

Chemical Weathering Patterns of Diluted Bitumen Spilled into Freshwater Limnocorrals.

Due to the sudden nature of oil spills, few controlled studies have documented how oil weathers immediately following accidental release into a natural lake environment. Here, we evaluated the weathering patterns of Cold Lake Winter Blend, a diluted bitumen (dilbit) product, by performing a series of controlled spills into limnocorrals installed in a freshwater lake in Northern Ontario, Canada. Using a regression-based design, we added seven different dilbit volumes, ranging from 1.5 to 180 L, resulting in oil-to-water ratios between 1:71,000 (v/v) and 1:500 (v/v). We monitored changes in the composition of various petroleum hydrocarbons (PHCs), including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and oil biomarkers in dilbit over time, as it naturally weathered for 70 days. Depletion rate constants (kD) of n-alkanes and PAHs ranged from 0.0009 to 0.41 d-1 and 0.0008 to 0.38 d-1, respectively. There was no significant relationship between kD and spill volume, suggesting that spill size did not influence the depletion of petroleum hydrocarbons from the slick. Diagnostic ratios calculated from concentrations of n-alkanes, isoprenoids, and PAHs indicated that evaporation and photooxidation were major processes contributing to dilbit weathering, whereas dissolution and biodegradation were less important. These results demonstrate the usefulness of large scale field studies carried out under realistic environmental conditions to elucidate the role of different weathering processes following a dilbit spill.

Long-term weathering difference in soil-like indicators of bauxite residue mediates the multifunctionality driven by microbial communities.

Long-term weathering enhances the stability of ecosystem services and alters the microbiome, however, its influences on the relationship between microbial diversity and multifunctionality are still poorly understood. Hereby, 156 samples (0-20 cm) from five artificially divided functional zones including central bauxite residue zone (BR), the zone near residential area (RA), the zone near dry farming area (DR), the zone near natural forest area (NF), and the zone near grassland and forest area (GF) were collected in a typical disposal area to determine the heterogeneity and development of biotic and abiotic properties of bauxite residue. Residues in BR and RA exhibited higher values of pH, EC, heavy metals, and exchangeable sodium percentage compared to those in NF and GF. Our results showed a positive correlation between multifunctionality and soil-like quality during long-term weathering. Microbial diversity and microbial network complexity responded positively to multifunctionality within the microbial community, which was parallel with ecosystem functioning. Long-term weathering promoted oligotrophs-dominated bacterial assemblages (mostly Acidobacteria and Chloroflexi) and suppressed copiotrophs (including Proteobacteria and Bacteroidota), while the response of fungal communities was lower. Rare taxa from bacterial oligotrophs were particularly important at the current stage for maintaining ecosystem services and ensuring microbial network complexity. Our results underscore the significance of microbial ecophysiological strategies in response to changes in multifunctionality during long-term weathering, and highlight the necessity of conserving and augmenting the abundance of rare taxa to ensure the stable provision of ecosystem functions in bauxite residue disposal areas.

Hydrochemistry and weathering at Pardo River basin, São Paulo State, Brazil.

This work was conducted at the Pardo River hydrographic basin, which is a federal watershed belonging to the Paranapanema River hydrographic basin (PRHB) in Brazil (São Paulo State and Paraná State). The aim was to realize an integrated hydrochemical and radiometric (U-isotopes and 210Po) approach, highlighting the water/soil-rock and surface water/groundwater interactions, with implications to the weathering processes occurring there. The study area has been often considered one of the best preserved/unpolluted river in São Paulo State, contributing to the water supply of several cities distributed along its banks. However, the results reported here suggest possible lead diffuse pollution caused by the use of phosphate fertilizers in agricultural activities taking place in the basin. The analyzed groundwaters and surface waters tend to be neutral to slightly alkaline (pH of 6.8-7.7), possessing low mineral concentration (total dissolved solids up to 500 mg/L). SiO2 is the major dissolved constituent in the waters, while bicarbonate is the dominant anion, and calcium is the preponderant cation. The effects of the weathering of silicates to control the dissolution of constituents in the liquid phase have been identified from some diagrams often utilized in hydrogeochemical studies. Chemical weathering rates have been estimated from hydrochemical data associated to analytical results of the natural uranium isotopes 238U and 234U concerning to samples of rainwater and Pardo River waters. The fluxes in this watershed are permitted to obtain the following rates: 11.43 t/km2 year (sodium), 2.76 t/km2 year (calcium), 3.17 t/km2 year (magnesium), 0.77 t/km2 year (iron), and 8.64 t/km2 year (uranium). This new dataset constitutes valuable information for people engaged on the management of the Pardo River watershed, as well as to researchers interested on comparative studies considering the available data from other basins worldwide.

Sodium removal from bauxite desilication product (sodalite) aided by chelating effects of inorganic and organic acids.

Dealkalization is a prerequisite to converting bauxite residue into non-hazardous materials that can be used for various upcycling applications. Structural alkali (Na+) lodged inside the densely packed aluminosilicate-cages of sodalite, the dominant desilication product from refining alumina, is a common culprit in the persistence of strong alkalinity of bauxite residue. The present study unravelled chemical and mineralogical processes involved in sodalite dealkalization, driven by organic and inorganic acids. These acids have different H+ dissociation coefficients and their anions have different chelation abilities with surface metal atoms of aluminosilicate minerals. The efficacy of sodium removal by exposure to the acids was found not only dependent on the acid strength (pKa), but also on the chelating property of dissociated conjugate anions. Following an initial H+-Na+ exchange, Na+ removal from sodalite was correlated with partial hydrolysis of aluminosilicate network and resultant chelating reactions with acid anions. The selection of organic and inorganic acids whose conjugate bases possess good chelating capability in the pH buffer zone 7-9 (e.g., oxalate or phosphate), would provide significant aid to the dealkalization process. The findings in this study are crucial in understanding the conversion of bauxite residue into a soil-like growth media (technosol) for sustainable mined land rehabilitation.

The recalcitrance and potential toxicity of polycyclic aromatic hydrocarbons within crude oil residues in beach sediments at the BIOS site, nearly forty years later.

The Arctic is a unique environment characterized by extreme conditions, including daylight patterns, sea ice cover, and some of the lowest temperatures on Earth. Such characteristics in tandem present challenges when extrapolating information from oil spill research within warmer, more temperate regions. Consequently, oil spill studies must be conducted within the Arctic to yield accurate and reliable results. Sites of the Baffin Island Oil Spill (BIOS) project (Cape Hatt, Baffin Island, Canadian Arctic) were revisited nearly 40 years after the original oil application to provide long-term monitoring data for Arctic oil spill research. Surface and subsurface sediment samples were collected from the intertidal zone of the 1981 nearshore oil spill experiment (Bay 11), from 1980 supratidal control plots (Crude Oil Point) and 1982 supratidal treatment plots (Bay 106). Samples were analyzed for Polycyclic Aromatic Hydrocarbons (PAHs) and alkylated homologues via Gas Chromatography - Mass Spectrometry (GC-MS). Our results suggest that total mean concentrations of all measured PAHs range from 0.049 to 14 mg/kg, whereas total mean concentrations of the 16 US EPA priority PAHs range from 0.02 to 2.1 mg/kg. The relative proportions of individual PAHs were compared between sampling sites and with the original technical mixture. Where available, percent loss of individual PAHs was compared with data from samples collected at the BIOS site, in 2001. All three sites featured samples where concentrations of various priority PAHs exceeded the established Interim Marine Sediment Quality Guidelines. All supratidal samples contained potentially toxic levels of PAHs. Even after nearly four decades of weathering, the recalcitrant crude oil residues remain a potential hazard for the native organisms. Continued monitoring of this unique study site is crucial for establishing a timeline for oil degradation, and to observe a reduction in toxicity over time.

The effect of temperature on hydrocarbon profiles and the microbial community composition in North Saskatchewan River water during mesoscale tank tests of diluted bitumen spills.

Despite many studies of diluted bitumen (DB) behavior during spills in saltwater, limited information is available on DB behavior in fresh water. This study examined the collective weathering processes on changes of fresh DB spilled in the North Saskatchewan River water and sediment mixture in a mesoscale spill tank under average air/water temperatures of 14 °C/15 °C and 6 °C/2 °C. Temporal changes of the hydrocarbon and microbial community compositions in the water column were assessed during the two 35-day tests under intermittent wave action. The contents of total organic carbon (TOC), benzene/toluene/ethylbenzene/xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAHs) in water decreased with time during both tests. The final contents remained at higher values in warm water (15 °C) than in cold water (2 °C) after the collective weathering processes. A quick response of the main phyla, Proteobacteria and Actinobacteria, was observed, where the members of Proteobacteria enriched during both DB spills. In contrast, the members of Actinobacteria reduced with time. The microbial shifts coincided with the changes of PAHs in the waters at both temperatures. A comparison of the physical properties and chemical compositions of fresh and weathered DBs at both temperatures showed that the oil had undergone weathering that increased oil density and viscosity due to losing the light oil fraction with boiling points < 204 °C and emulsifying with water. This corresponded to losses of 19.0 wt% and 17.2 wt% of the fresh DB at 15 °C and 2 °C tests, respectively. For organic compounds in the DB with boiling points > 204 °C, there were small losses of saturates and 2- & 3-ring PAH aromatics (more during the 15 °C test than the 2 °C test), and negligible losses in the subfractions of resins and asphaltenes by the ends of the tests. <1.0 wt% of the DB was recovered from the bottom sediment, regardless of the temperature.

Tar ball pollution under the influence of ocean circulation in the Bohai Sea, China.

The deposition of tar balls of unknown sources on the coast poses a great threat to the fishery, tourism and coastal biodiversity in the Bohai Sea. This work aimed to identify the sources of tar balls by using oil fingerprint technique. Tar ball samples were collected from the seashore of two islands of the western Bohai Sea and divided into two groups (Group I and Group II). Principal component analysis showed that although Caofeidian oilfield was one of the closest oilfields to the sampling area it was not a source. Fingerprints of characteristic hopanes and steranes showed that samples of Group I were similar to the crude oils from the nearby Jidong oilfield, and samples of Group II were similar to the Penglai-19-3 crude oils. Combined with cross-plots of the samples and the reference oils, it indicated that Group I may come from Jidong and Group II may come from Penglai-19-3. The weathering characteristics of alkanes and polycyclic aromatic hydrocarbons showed that the samples were affected by natural weathering processes (e.g., evaporation, photooxidation and biodegradation). It revealed that oil pollution from the nearby oilfields can also affect other areas under the influence of ocean circulation. It is the first study on source identification of tar balls from the Bohai Sea and the effects of ocean circulation on the tar ball transport. This study can considerably help to further understand the evolution of tar balls and consequently determine their sources.

Carbonate weathering, phosphate fertilizer, and hydrologic controls on dissolved uranium in rivers in the US Corn Belt: Disentangling seasonal geogenic- and fertilizer-derived sources.

Soil and bedrock weathering and phosphate (P) fertilizers may both contribute to the uranium (U) load of rivers in agricultural regions, but controls over their relative influence are not well known. This study investigates the U sources to rivers in Ohio, United States, part of the Eastern Corn Belt in the Mississippi River watershed. We present a regional picture of seasonal U sources to rivers based on four analyses: 1) a spatial analysis of legacy soil and water data, 2) new measurements of U and carbonate weathering products from rivers at 50 locations across the state collected seasonally over two years, 3) a weekly time series with additional 234U/238U (n = 5) and 87Sr/86Sr (n = 5) measurements from an agricultural river, and 4) a mass-balance approach to U addition to the landscape based on reported P fertilizer use. Uranium concentrations in surface waters collected statewide ranged 0.1-21 nM (n = 132), with significantly higher concentrations in the glaciated agricultural portion of the state (mean = 7.3 nM; n = 105) than the non-glaciated portion (mean = 2.0 nM; n = 24). Concentrations in the glaciated region were highest during the spring and summer and decreased during baseflow. In the time-series, concentrations were ~7 nM during baseflow and ~14 nM during intermediate seasonal discharge conditions, indicating a second more surficial endmember source of U in addition to bedrock weathering that is well correlated with other carbonate weathering products. Systematic increases in 87Sr/86Sr and decreases in 234U/238U with increasing discharge confirm a changing source of carbonate and U weathering and a third surficial endmember during high discharge events. Our mass balance approach and geochemical analysis suggest that elevated U concentrations are the result of carbonate weathering deep in the soil column during elevated seasonal flow. Further work on U dynamics in agricultural rivers is required to understand mechanism controlling seasonal changes in U concentrations and 234U/238U in downstream rivers and U flux.

Influence of natural exposure on castor oil based polyurethane reinforced with waste tire rubber.

Waste tire rubber (WTR) has been extensively generated worldwide due to mobility needs growth. About 1.5 billion units are generated annually, constantly discharged in the environment with a few reusability alternatives. Therefore, rubber recovery methods and these residues' transformation into a cost-effective product have gained attention. Aiming to minimize the usage of fossil resources and contributes to a circular economy, it was analyzed the usage of WTR particles (5-20% by weight) in castor oil-based polyurethane foams under natural aging to promote a holistic view of all factors involved in the performance of the foams. Morphological, thermal, chemical, and mechanical properties were determined before and after exposure to open air to observe the impact of photo-oxidation and hydrolysis. The increase in viscosity of pre-polymer during the rubber loading produced greater density foams with smaller cell sizes than neat PU, in which the average cell size increased after the weathering. The rubber contributes to enhancing the compressive behavior in the non-exposed samples. After exposure, the results suggest that degradation may act to increase the crosslinking density even with the presented structural changes such as yellowing and voids. Regarding thermal stability, the rubber promotes a slight decay in the ability to resist a heat flow before and after weathering. Still, the char yield increased, showing a possibility of better fire retardancy for composites. FTIR and UV-vis showed chemical structure changes as Photo-Fries network rearrangement, Norrish I random chain scission, and Norrish II ß-scission. Besides, UV-vis revealed the maximum absorbance in the UVB region, showing that the PU reinforced by WTR can be a promising material for civil coatings.

Nitrogen-based symbioses, phosphorus availability, and accounting for a modern world more productive than the Paleozoic.

Evolution of high-productivity angiosperms has been regarded as a driver of Mesozoic ecosystem restructuring. However, terrestrial productivity is limited by availability of rock-derived nutrients such as phosphorus for which permanent increases in weathering would violate mass balance requirements of the long-term carbon cycle. The potential reality of productivity increases sustained since the Mesozoic is supported here with documentation of a dramatic increase in the evolution of nitrogen-fixing or nitrogen-scavenging symbioses, including more than 100 lineages of ectomycorrhizal and lichen-forming fungi and plants with specialized microbial associations. Given this evidence of broadly increased nitrogen availability, we explore via carbon cycle modeling how enhanced phosphorus availability might be sustained without violating mass balance requirements. Volcanism is the dominant carbon input, dictating peaks in weathering outputs up to twice modern values. However, times of weathering rate suppression may be more important for setting system behavior, and the late Paleozoic was the only extended period over which rates are expected to have remained lower than modern. Modeling results are consistent with terrestrial organic matter deposition that accompanied Paleozoic vascular plant evolution having suppressed weathering fluxes by providing an alternative sink of atmospheric CO2 . Suppression would have then been progressively lifted as the crustal reservoir's holding capacity for terrestrial organic matter saturated back toward steady state with deposition of new organic matter balanced by erosion of older organic deposits. Although not an absolute increase, weathering fluxes returning to early Paleozoic conditions would represent a novel regime for the complex land biota that evolved in the interim. Volcanism-based peaks in Mesozoic weathering far surpass the modern rates that sustain a complex diversity of nitrogen-based symbioses; only in the late Paleozoic might these ecologies have been suppressed by significantly lower rates. Thus, angiosperms are posited to be another effect rather than proximal cause of Mesozoic upheaval.

Source identification and weathering processes of tar ball deposited Qinhuangdao coast along the Bohai Sea, China.

Deposition of tar balls on the Qinhuangdao beaches along the coasts of the Bohai Sea (China) could affect people's leisure activities and tourism, and even affect the marine ecosystem. In 2020, representative tar balls collected from Qinhuangdao beaches, fingerprint analysis based on diagnostic ratios suggested that these tar balls were all very similar and may belong to the same source. Source identification by cross plot and principal component analysis (PCA), showed that the tar balls were likely from Penglai 19-3 crude oil. The weathering characterizations based on polycyclic aromatic hydrocarbons (PAHs), alkanes parameters and unresolved complex mixture (UCM), indicated that the tar balls had been significantly influenced by natural weathering processes such as evaporation, biodegradation and photooxidation. The study of this leakage provides a powerful support for determining the leakage source, evaluating the potential weathering mechanism and determining the accident liability. This is the first time to use fingerprint technology to identify the source of tar balls in Qinhuangdao coastal zone in the Bohai Sea.

PAH depletion in weathered oil slicks estimated from modeled age-at-sea during the Deepwater Horizon oil spill.

During time-periods oil slicks are in the marine environment (age-at-sea), weathering causes significant changes in composition and mass loss (depletion) of oil spill chemicals including the more toxic polycyclic aromatic hydrocarbons (PAHs). The goal of this study was to estimate the age-at-sea of weathered oil slicks using the oil spill module of the Connectivity Modeling System and to use this age to interpret PAH concentration measurements. Percent depletion (PD) for each measurement was computed as the percentage difference between the original and measured PAH concentration in the crude oil and weathered oil slicks, normalized upon the mass losses relative to hopane. Mean PD increased with estimated age-at-sea for all PAHs. Less PD was observed for alkylated than for parent PAHs, likely due to decreasing vapor pressure with increasing degree of alkylation. We conclude that estimated age-at-sea can be used to explain PAH depletion in weathered oil slicks. We propose PAH vapor pressure can be coupled with the model to expand capacity for predicting concentration distributions of individual parent and alkylated PAHs in weathered oil along the coastline. This new module will advance the science supporting oil spill response by providing more certain estimates of health risks from oil spills.