Natural Weathering Research Articles

Heavy metal contamination, distribution and source apportionment in the sediments from Kavvayi Estuary, South-west coast of India

Heavy metal contamination in sediments poses serious threat to ecosystem and human health through food web. In this study, surface sediment samples from Kavvayi estuary were analyzed to understand the sources and pollution levels of heavy metals. The results revealed that the average contents (μg g−1) of eight selected heavy metals followed the order of Mn (65–795) > Cr (30–442) > Co (30–250) > Ni (15–175) > Zn (20–120) > Cu (5–55) > Pb (5–40). Enrichment factor (EF) and contamination factor (CF) analyses revealed that Pb, Ni and Cr shows moderate pollution levels, whereas Co indicates severe pollution levels. The rests of the heavy metals (Zn, Cu and Mn) were at no to low pollution levels. The correlation matrix combined with multivariate principal component analysis suggests the heavy metals, except for Co, mainly originated from natural weathering and erosion of rocks and soils in the catchment. The results of this study provide a comprehensive assessment of heavy metal contamination in the sediments of the Kavvayi region. The result can aid the development of effective remediation strategies and improve government decision-making and coastal management.

Design a Mathematical Planning Approach to Optimize the Supply Chain Taking Into Account Uncertainties In Distributors

Abstract With the globalization of markets and increasing competition in global markets, the attempts of organizations to survive in this market has increased and has resulted in the emergence of the philosophy of Supply Chain Management. There is uncertainty in the reliability of supply chain facilities for reasons such as natural disasters, terrorist attacks, labor errors, and weather conditions. Therefore, when making strategic decisions, the system will continue to operate with minimal damage. Over the course of this study, the uncertainty of supplier layers in the supply chain has been modeled. To meet that aim, the issue of supply chain, including producers, warehouses, suppliers and consumers are considered. To calculate the cost of breakdowns due to the non-functioning of distributors, the scenario-building method has been utilized. Finally, the desired model is solved with Gomez software and the results are presented. The result of the study demonstrate the efficiency of this model in the facility location decision-making in supply chains.

Magnetic Extraction of Weathered Tire Wear Particles and Polyethylene Microplastics.

Magnetic extraction offers a rapid and low-cost solution to microplastic (MP) separation, in which we magnetize the hydrophobic surface of MPs to separate them from complex environmental matrices using magnets. We synthesized a hydrophobic Fe-silane based nanocomposite (Fe@SiO2/MDOS) to separate MPs from freshwater. Pristine and weathered, polyethylene (PE) and tire wear particles (TWP) of different sizes were used in the study. The weathering of MPs was performed in an accelerated weathering chamber according to ISO 4892-2:2013 standards that mimic natural weathering conditions. The chemical properties and morphology of the Fe@SiO2/MDOS, PE and TWP were confirmed by Fourier transform infrared spectroscopy and Scanning electron microscopy, respectively. The thermal properties of PE and TWP were evaluated by Thermogravimetric analysis. Using 1.00 mg of Fe@SiO2/MDOS nanocomposite, 2.00 mg of pristine and weathered PE were extracted from freshwater; whereas, using the same amount of the nanocomposite, 7.92 mg of pristine TWP and 6.87 mg of weathered TWP were extracted. The retrieval of weathered TWP was 13% less than that of pristine TWP, which can be attributed to the increasing hydrophilicity of weathered TWP. The results reveal that the effectiveness of the magnetic separation technique varies among different polymer types and their sizes; the weathering of MPs also influences the magnetic separation efficiency.

Protective treatments for copper alloy artworks: preliminary studies of sodium oxalate and limewater effectiveness against bronze disease

Nantokite (CuCl) locked inside subsurface micro-pits has been recognised as the driving force to the form of corrosion called bronze disease. The use of the traditional corrosion inhibitor benzotriazole is questioned because of toxicity. So there is a need for alternative conservation treatments. This work is focused on the experimental design to test the effectiveness of sodium oxalate followed by treatment with limewater to face bronze disease on outdoor bronzes. A number of foundry bronze coupons were exposed to weathering at Genoa Experimental Marine Station (GEMS) exposure site and sprayed twice a week with a 5% NaCl solution for the first 124 days. After 562 days of natural weathering, the patinas on coupons were characterised with non-destructive techniques (NDT) and the presence of nantokite was verified. We designed a workflow, as similar as possible to conservation treatments on real artworks, to test a 3% w/v sodium oxalate treatment with two different application times, with or without limewater, on the coupons. The effectiveness of the treatments was analysed by comparison of surface properties by several NDT measurements. A statistical approach and XRD measurements directly on the corroded bronze surfaces are suggested as an effective way to characterise and compare the overall behaviour of bronze disease treatments for conservation.

Durability of Pultruded GFRP Rebar Subjected to Natural Weathering in Alkaline Solution for 10 Years

Durability of Pultruded GFRP Rebar Subjected to Natural Weathering in Alkaline Solution for 10 Years

Effect of different starch contents on physical, morphological, mechanical, barrier, and biodegradation properties of tapioca starch and poly(butylene adipate‐co‐terephthalate) blend film

AbstractStudy on degradation behaviors of biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) blended with different compositions of thermoplastic starch (TPS) under soil burial and natural weathering environments is vital in order to predict the product service‐life and planning for in situ biodegradation after product disposal. In this article, different compositions of TPS (0%, 20%, 40%, 50%, and 60%) were compounded with PBAT using single screw extruder. The samples were characterized for their tensile properties, fractured surface morphology, water barrier and surface hydrophorbicity properties in order to investigate the effect of starch fractions in PBAT blends. The degradation behavior under natural weathering and soil burial conditions was also determined during the 9 months duration by observing the change of physical appearance, weight loss, surface morphology, chemical structural, and tensile properties. The findings showed that the addition of TPS (20%, 40%, 50%, and 60%) had led to a reduction in tensile strength (41.47%, 60.53%, 63.43%, and 68.53%), and reduction in elongation at break (42.92%, 92.1%, 92.23%, and 93.22%, respectively) and water barrier properties. The findings also showed that there were distinct degradation behavior under both conditions. Upon exposure to natural weathering, photodegradation and Norrish type I & II occurred whereas under the soil burial condition, hydrolytic, and enzymatic degradation take places. Sample with the highest starch contents underwent the highest weight loss and reduction in tensile properties under both environments. The findings in this study are useful in order to investigate the feasibility of PBAT/Tapioca starch blends for biodegradable plastic film for various industrial applications especially in packaging and agricultural mulch.

Experimental Evidence from the Field that Naturally Weathered Microplastics Accumulate Cyanobacterial Toxins in Eutrophic Lakes.

Freshwater ecosystems with recurring harmful algal blooms can also be polluted with plastics. Thus the two environmental problems may interact. To test whether microplastics influence the partitioning of microcystins in freshwater lakes, we examined the sorption of four microcystin congeners to different polymers of commercially available plastics (low-density polyethylene, polyethylene terephthalate, polyvinyl chloride, and polypropylene). We conducted three experiments: a batch sorption experiment in the laboratory with pristine microplastics of four different polymers, a second batch sorption experiment in the laboratory to compare pristine and naturally weathered microplastics of a single polymer, and a 2-month sorption experiment in the field with three different polymers experiencing natural weathering in a eutrophic lake. This series of experiments led to a surprising result: microcystins sorbed poorly to all polymers tested under laboratory conditions (<0.01% of the initial amount added), irrespective of weathering, yet in the field experiment, all polymers accumulated microcystins under ambient conditions in a eutrophic lake (range: 0-84.1 ng/g). Furthermore, we found that the sorption capacity for microcystins differed among polymers in the laboratory experiment yet were largely the same in the field. We also found that the affinity for plastic varied among microcystin congeners, namely, more polar congeners demonstrated a greater affinity for plastic than less polar congeners. Our study improves our understanding of the role of polymer and congener type in microplastic-microcystin sorption and provides novel evidence from the field, showing that naturally weathered microplastics in freshwater lakes can accumulate microcystins. Consequently, we caution that microplastics may alter the persistence, transport, and bioavailability of microcystins in freshwaters, which could have implications for human and wildlife health. Environ Toxicol Chem 2022;41:3017-3028. © 2022 SETAC.

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.

Experimental thermo-hydric study to simulate natural weathering conditions

• Development of an experimental setup realistically reproducing thermo-hydric strain. • Estimation and localization of the generated thermo-hydric stress. • Comparison of stones through the assessment of long-term stone weathering. Laboratory aging tests allow to indirectly study stones behaviors on a monument. Classic aging tests are designed to compare materials resistance to different weathering mechanisms: they are more intense than the on-site conditions and do not reflect the real weathering intensity and kinetics. To study the real weathering on a monument and the materials behavior, an experimental setup using realistic experimental conditions was designed. The stones of a monument in Reims (France) were studied through this experimental setup: the Courville limestone (original stone) and the Savonnières limestone (restoration stone). The environmental variations were taken into account through a previous climatic monitoring of the monument. The realistic experimental setup was designed to reproduce, in a stone sample, the thermal and hydric strains experienced by a stone on a vertical wall. Temperature and humidity variations were applied unidirectionally through one surface, defined as the exposed surface. The temperature and humidity variations were based on typical variations identified with an in-situ monitoring of the basilica: sunny day, cold and warm rainy days, and frost day. The mild conditions, similar to the on-site conditions, did not visibly damage the samples and their behavior was studied through temperature and strain variations. The Courville limestone appeared more sensitive to the thermo-hydric variations of the typical days, particularly by the presence of water in the porous network than the Savonnières. Water generated high stress in the wet layer due to hydric expansion and at the wet/dry interface due to strain difference. Furthermore, the ice formation in the wet layer could induce high stress. On the contrary, the Savonnières limestone did not appear sensitive and little to no stress was generated during the typical days. The realistic setup allowed a simulation of the temperature and water repartitions in the samples close to on-site conditions. It provided relevant information in this specific environment and could help anticipate stone weathering on the monument.

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.

Soil microplastics – current research trends and challenges: preliminary results of the earthworm Eisenia fetida impact on glitters

Abstract This paper shortly introduces the topic of soil microplastics by presenting a comprehensive review of the current state of the art in this field. It focuses mainly on the role of primary microplastics, particularly glitters, due to their large surface-to-volume ratio. From conclusions about current challenges and research directions, after analysis of the crucial “knowledge gaps “, one can point out the lack of a detailed description of the influence of microplastics on biota. The earthworms are promising model organisms that may play in soil ecosystems a similar role to the bivalves in waters. Thus, this mainly review paper was enlarged by the preliminary results of studies on glitters and bioglitters naturally aged in milli-Q water and soil with Eisenia fetida. Fourier-transform Infrared (FTIR, microscopy in the reflectance mode) and Raman spectroscopy (780 nm) were used to identify the subsequent notable changes in studied materials. The presence of the polymer (PET) core in the standard glitter particles is confirmed. In addition, the leakage of dyes from bioglitters was observed within the 9-week experiment. Tested bioglitters decompose in a slightly different way. Blue and pink pigments had entirely different stability as only one disappeared without a trace under UV light (blu), and the other remained stable in solution, confirmed by UV-Vis spectra. The nephelometry shows sedimentation of glitters after turbulent agents in the environment. This paper presents the natural weathering of primary microplastics in the presence of Eisenia fetida.

Characterization of Barium Hydroxide Used as Consolidating Agent for Monumental Surfaces in Venice

Barium hydroxide was one of the most widely used inorganic materials to consolidate calcareous stones during the 19th and 20th. The consolidation process occurs through a carbonation reaction. Several researchers studied the consolidation mechanism; however, the results are sometimes in conflict. More experimental work using modern analytical techniques and a multi-analytical approach is necessary to shed light on the mechanisms involved. This research aims to validate the chemical composition of the developed secondary products and to evaluate the treatment’s effectiveness over time. Carrara marble and Vicenza white limestone were treated and subjected to natural, artificial, and biological weathering. Furthermore, only a few microsamples were collected from Venetian historical artifacts treated in the 1960s and 1970s. Microscopic observations, sponge tests, FTIR, SEM-EDX, and microbiological analyses investigated the stability of the treatment over time and ascertained the chemical composition of the acicular crystals developed from the carbonation reaction of barium hydroxide. The results prompted a number of considerations useful for future restorations and for developing innovative compounds for consolidation interventions.

YEREL METEOROLOJİK VERİ KAYITLARI İLE SEKBANDEMİRLİ KIRSAL BÖLGESİNDE GÜNLÜK VE MEVSİMSEL FOTOVOLTAİK ISI ADASININ İNCELENMESİ VE DEĞERLENDİRİLMESİ

Photovoltaic Power Plants have a considerable share among solar energy conversion technologies toward environmentally sustainable and economically feasible electricity production. However, when a rural region's land surface formed by natural soil types is covered by a Photovoltaic Power Plant (PVPP)'s dark-colored solar modules in large numbers, an artificial albedo (reflectivity) change is expected on that surface. Because of the heat exchange between these modules and the air surrounding them due to albedo alteration, the region's natural weather conditions may experience Photovoltaic Heat Island Effect (PVHIE) as a result of external and time-dependent air temperature oscillations caused by the warming-cooling cycles of solar modules. To observe and analyze a possible PVHIE trend, it has been conducting a field study project since October 2017 for a PVPP near the Sekbandemirli rural region in the Kutahya city of Turkey. The weather data, including air temperature and wind (direction and speed) at every 10-minute and hourly intervals, are collected by the three weather monitoring stations installed at the specific locations inside and outside the PVPP field. The plant's hourly average power output and module temperature data can also be monitored. After conducting statistical, correlational, and graphical analyses, the results show some temporal PVHI formations at the PVPP field center daily and on a seasonal basis. The plant center's air temperature tends to be warmer (up to the 6°C difference) during daytimes and colder (up to the (-3)°C difference) during nighttimes.

Bakır esaslı kimyasal (Korasit KS) ile emprenye edilen ağaç malzemenin doğal yaşlandırma sonrası üst yüzey özellikleri

In this work, the surface characteristics of Oriental beech (Fagus orientalis L.) wood impregnated with Korasit KS, a water-based and copper-containing impregnation substance, were examined after three months of natural weathering. The impregnation material was penetrated into the wood material at 3% and 6% concentration levels according to the ASTM D 1413-07 (ASTM 2007) standard. According to the results obtained, the L* values of all samples decreased after natural weathering. Furthermore, impregnated samples provided better color stability than control samples. Moreover, this stability increased as the concentration amount increased in the impregnation process. While the gloss of all samples decreased after natural weathering, this decrease was more in control samples. According to the surface roughness test results, Ra, Rz and Rq values of all samples increased after natural weathering. This increase was more in the impregnated samples.

Wettability after Artificial and Natural Weathering of Polyethylene Terephthalate

The weathering of plastics is always accompanied by a change in surface properties, especially wettability in the case of water. For plastics weathering in an aquatic environment, wettability plays an important role in transport, sedimentation, and dispersion in the water body. To quantify wettability, contact angle measurement is a fast and convenient method that requires little experimental effort. This technique was used with the aim of systematically discussing how measured values of contact angles can contribute to the assessment of the weathering state. Using polyethylene terephthalate (PET), wetting was analyzed on samples from artificial weathering and from controlled, natural weathering. Surface analytical methods were used (Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), ultraviolet and visible light spectroscopy (UV/VIS)) to analyze the parameters affecting the contact angle: (i) chemical bond breaking and formation, (ii) eco-corona formation and biofilm growth, and (iii) change in surface structure and roughness. It was found that wettability with water increased during weathering in all cases. The reasons for this varied and depended on the method of weathering. The improved wettability during artificial weathering was due to changes in the polymer surface chemistry. In natural weathering, however, the formation of eco-corona and biofilm was responsible for the changes.

The Impact of Weather Conditions on Biocides in Paints.

Weather conditions affect biocides on exposed outer surfaces on constructions. Contact with water causes hydrolysis and leaching of substances. Ultraviolet radiation may induce photolysis. As a result, a mixture of biocidal active substances and transformation products can be emitted into the environment. In a semi-field study, leaching of the biocidal active substances terbutryn, diuron, octylisothiazolinone, carbendazim, and selected transformation products was observed for two paints containing either a white or a red pigment. Painted test panels were exposed to natural weathering for about 1.5 years. Runoff samples were analyzed during the course of the experiment. At the end of the study, residues of biocidal active substances and transformation products were determined in sections of the test panels. Emissions of substances were mainly observed during the first few months of the experiments. Increased emissions of transformation products were observed during periods of increased global radiation and subsequent periods with relatively high amounts of driving rain. Different patterns of transformation products were observed, especially for terbutryn, both for paints containing different pigments and in experiments that were started in different periods of the year, as well as during different periods of the experiments.

Extraction of rare earth elements from a South American ionic clay

Ionic clays, formed by the natural weathering of REE-bearing minerals and the adsorption of the resulting liberated REE ions onto the clay surface, are an important resource for critical rare earth elements (REEs). Here, a two-step desorption process using ammonium sulfate with active pH adjustment using sulfuric acid was developed to extract REEs from a South American clay. The desorption process was optimized using response surface methodology approach and the optimum operating conditions were determined to be 0.15 mol/L ammonium sulfate, pH 3, liquid to solid ratio of 3/1, and 25 °C with 20 min residence time. It is shown that this ionic clay is significantly different from previously reported clays, e.g., from southern China, as it consists of three modes of REEs, including ion-exchanged REEs physically adsorbed on the clay surface, hydrolyzed REEs chemically adsorbed on the clay surface, and mineralized (non-desorbable) REEs within the clay. Mechanistic investigations through progressive acidification during desorption and adsorption isotherms show that REE desorption/adsorption occurs due to the combined action of physical ion exchange adsorption and surface complexation chemical adsorption, with their relative importance depending on the pH of the system and the amount of sulfate anions present within the solution. This work supports overall efforts to utilize ionic clays as a relatively new resource for REEs to empower the development and adoption of modern green technologies such as wind turbines and electric vehicles.

Natural weathering of spruce wood chemically modified by re‐used ε‐caprolactone solution

AbstractIncreasing environmental pressures over the last few years have led to attention for non‐biocide treatments in the wood protection field. The ε‐caprolactone modification of wood by substitution or blocking of hydroxyl groups with hydrophobic poly(ε‐caprolactone) (PCL) is one of the novel modification methods developed in recent years. In this study, ring‐opening polymerisation of ε‐caprolactone in wood cell walls was evaluated by the third and sixth re‐use of recovered monomer and by oven‐curing method. Spruce samples were modified by re‐used ε‐caprolactone and exposed to the natural weathering agents for 12 months. After weathering, the colour change, surface roughness measurements, and macroscopic and ultra‐microscopic observations revealed that the modified wood had better surface properties than reference wood. Fourier‐transform infrared (FTIR) analysis proved that PCL could be found on the weathered surface up to the sixth month, but very little amount was detected on the surfaces with a longer weathering period. The results clearly showed that the efficiency of PCL modification with re‐use of the monomer solution was sufficient during the initial weathering periods, but efficiency was reduced after a prolonged exposure period.

Soil core study indicates limited CO2 removal by enhanced weathering in dry croplands in the UK

The application of crushed silicate minerals to agricultural soils has been suggested as a route to enhance weathering rates and increase CO2 drawdown. Laboratory studies have attempted to evaluate the potential of enhanced weathering as a CO2 removal technique but do not simulate the geochemical complexity of soil environments, and studies in the field are limited in the nature of data they can collect. To overcome these limitations, this study uses an experimental set-up which fully encapsulates field conditions in a controlled setting using soil cores removed from UK cropland and treated with crushed basalt. Cores were exposed to natural weather conditions throughout a 14-month time series, and soil solution was sampled in 10–20 cm intervals in the core to provide insight into the fate of dissolution products with soil depth.This study assessed the rate and chemistry of basalt dissolution 8 months after addition at a high application rate (100 t basalt ha−1) using direct measurements from a UK soil. Assuming conclusions drawn from this study are representative of field-scale enhanced weathering, findings indicate that a set application of basalt to lime-rich, unirrigated UK soils releases alkalinity at a rate of 310 ± 30 eq ha−1 yr−1 and could remove 10.2 ± 0.8 kgCO2 ha−1 yr−1. Accumulation of undissolved basalt may also lead to large and irreversible changes to soil compositions following repeated application. When considering variation in hydrology around the UK, we assess the drawdown potential of application of basalt to all UK arable land as 1.3 ± 0.1 MtCO2 yr−1 which is equivalent to 3% of current UK agricultural CO2 emissions. This is 5- to 25- fold slower than previous modelled assessments, likely due to complexities of soil systems and to water limitation on alkalinity release. Further research is needed to fully assess controls on the potential of enhanced weathering in the real-world environment, across a range of hydrological and soil environments, before the approach is substantively scaled-up for CO2 removal.

Impact of natural weathering on source rocks: Organic and inorganic geochemical evidence from the Triassic Chang 7 outcrop profile in Tongchuan of the Southern Ordos Basin (China)

Exposure of buried source rocks at or near the surface causes organic matter (OM) to be subjected to loss through weathering impacts. A detailed organic and inorganic investigation of the natural weathering of the Triassic Chang 7 Yishicun Profile in Tongchuan City of the Ordos Basin revealed pronounced changes in bulk, molecular, mineral, and elemental compositions. In this study, systematic and visible variations caused by natural weathering were shown in the amount and composition of both organic (kerogen and extractable organic matter [EOM]) and inorganic matter (minerals and elements). The results indicate that natural weathering could substantially affect the characteristics of source rocks at a depth of 2 m from the surface, resulting in a 41% decrease in total organic carbon (TOC) and a 75% loss of EOM. Furthermore, changes were noted in kerogen elemental compositions, fractional compositions of EOM, and some geochemical parameters from Rock-Eval pyrolysis. The mineral and major, trace, and rare earth element (REE) compositions of the outcrop samples were also analysed and compared. The weathering of source rocks was mainly due to the influence of surface water leaching and biodegradation of the OM. This resulted in the oxidation of kerogen and the preferential depletion of low-carbon-number n-alkanes and low-molecular-weight high-water-solubility biomarkers. This has led to bias in petroleum geochemical interpretation based on these organic geochemical parameters. The major elemental composition indicated that the outcrop profile was moderately weathered. Moreover, some commonly used palaeoenvironmental geochemical proxies, including U/Th, AU, Mo, Sr/Ba, Sr/Cu, and P/Ti, display varying degrees of weathering-related alteration. However, other palaeoenvironmental proxies such as V/(V + Ni), Ni/Co, V/Cr, δU, and Ceanom experienced little variation and remained reliable for environmental interpretation. Thus, petroleum resource evaluation and sedimentary environmental analysis of source rocks based on outcrop samples should consider the effects of natural weathering.