•Curiosity’ ChemCam and CheMin instruments are used to assess alteration in sedimentary rocks.•The chemical alteration index indicates substantial weathering (CIA > 50).•Mineralogy indicates ...clay-rich, mafic mineral-free rocks consistent with substantial alteration.•Results support substantial open system weathering at Gale crater.
From Sol 750 to 1550, the Curiosity rover documented>100 m thick stack of fine-grained sedimentary rocks making up part of the Murray formation, at the base of Mt Sharp, Gale crater. Here, we use data collected by the ChemCam instrument to estimate the level of chemical weathering in these sedimentary rocks. Both the Chemical Index of Alteration (CIA) and the Weathering Index Scale (WIS) indicate a progressive increase in alteration up section, reaching values of CIA of 63 and WIS of 25%. The increase in CIA and WIS values is coupled with a decrease in calcium abundance, suggesting partial dissolution of Ca-bearing minerals (clinopyroxene and plagioclase). Mineralogy from the CheMin X-ray diffraction instrument indicates a decrease in mafic minerals compared with previously analyzed strata and a significant proportion of phyllosilicates consistent with this interpretation. These observations suggest that the sediments were predominantly altered in an open system, before or during their emplacement, contrasting with the rock-dominated conditions inferred in sedimentary deposits analyzed at Yellowknife Bay.
•Diagenetic Ca-sulfate veins are pervasive along Curiosity traverse in Gale crater.•ChemCam highlights local enrichments in Fe and Mg in these features.•Passive reflectance shows that both ferric and ...ferrous phases are identified.•Groundwater redox and pH conditions appear variable along the stratigraphy.
ChemCam has observed a wide range of diagenetic features along the Curiosity rover traverse including pervasive Ca-sulfate veins. Observations by multiple instruments on Curiosity indicate that these veins are hydrated, formed during diagenetic fluid event(s). In this study, we delve into the chemical variability in these Ca-sulfate bearing veins and have identified two subsets in the Murray formation with enrichments in Fe and Fe + Mg. These chemical trends do not reflect a sampling mixture with the surrounding host rock but likely indicates the presence of authigenic phases formed during the emplacement of these veins. Based on passive reflectance spectral analysis and correlation with other elements, Fe3+ oxides and/or sulfates are proposed to account for the Fe-rich observations in the vicinity of the Naukluft Plateau whereas the Fe + Mg trend is also observed in adjacent dark-toned features with elevated Mn and P near the Old Soaker outcrop. The specific localization of these observations in the Gale stratigraphy implies changing pH and redox conditions in the groundwater at the time of formation of these veins, from oxidizing and likely more acidic near the Naukluft Plateau to more reducing conditions in the upper part of the Murray formation.
Manganese has been observed on Mars by the NASA Curiosity rover in a variety of contexts and is an important indicator of redox processes in hydrologic systems on Earth. Within the Murray formation, ...an ancient primarily fine‐grained lacustrine sedimentary deposit in Gale crater, Mars, have observed up to 45× enrichment in manganese and up to 1.5× enrichment in iron within coarser grained bedrock targets compared to the mean Murray sediment composition. This enrichment in manganese coincides with the transition between two stratigraphic units within the Murray: Sutton Island, interpreted as a lake margin environment, and Blunts Point, interpreted as a lake environment. On Earth, lacustrine environments are common locations of manganese precipitation due to highly oxidizing conditions in the lakes. Here, we explore three mechanisms for ferromanganese oxide precipitation at this location: authigenic precipitation from lake water along a lake shore, authigenic precipitation from reduced groundwater discharging through porous sands along a lake shore, and early diagenetic precipitation from groundwater through porous sands. All three scenarios require highly oxidizing conditions and we discuss oxidants that may be responsible for the oxidation and precipitation of manganese oxides. This work has important implications for the habitability of Mars to microbes that could have used Mn redox reactions, owing to its multiple redox states, as an energy source for metabolism.
Plain Language Summary
In May 2017, the NASA Curiosity rover observed higher than usual amounts of manganese in the lakebed rocks within Gale crater, Mars. These sedimentary rocks have larger grain sizes than what is typical for the lakebed rocks in Gale crater. This may indicate that the original sediments were formed in a river, delta, or near the shoreline in the ancient lake. In this paper, we discuss how manganese could have been enriched in these rocks—for example, by percolation of groundwater through the original sediments or through the rock afterward—and what oxidant could be responsible for the precipitation of manganese in the rocks. On Earth, manganese becomes enriched because of oxygen in the atmosphere and this process is often sped up by the presence of microbes. Microbes on Earth can use the many oxidation states of manganese as energy for metabolism; if life was present on ancient Mars, the increased amounts of manganese in these rocks along the lake shore would be a helpful energy source for life.
Key Points
Enrichments of MnO are observed in bedrock and diagenetic features near a stratigraphic boundary between possible lake margin and lake sediments
Manganese precipitation may have occurred along a lake shoreline via authigenic or early diagenetic scenarios
All alteration scenarios require persistent water and highly oxidizing conditions in what would have been a habitable environment
Geochemical results are presented from Curiosity's exploration of Vera Rubin ridge (VRR), in addition to the full chemostratigraphy of the predominantly lacustrine mudstone Murray formation up to and ...including VRR. VRR is a prominent ridge flanking Aeolis Mons (informally Mt. Sharp), the central mound in Gale crater, Mars, and was a key area of interest for the Mars Science Laboratory mission. ChemCam data show that VRR is overall geochemically similar to lower‐lying members of the Murray formation, even though the top of VRR shows a strong hematite spectral signature as observed from orbit. Although overall geochemically similar, VRR is characterized by a prominent decrease in Li abundance and Chemical Index of Alteration across the ridge. This decrease follows the morphology of the ridge rather than elevation and is inferred to reflect a nondepositionally controlled decrease in clay mineral abundance in VRR rocks. Additionally, a notable enrichment in Mn above baseline levels is observed on VRR. While not supporting a single model, the results suggest that VRR rocks were likely affected by multiple episodes of postdepositional groundwater interactions that made them more erosionally resistant than surrounding Murray rocks, thus resulting in the modern‐day ridge after subsequent erosion.
Plain Language Summary
Results from the ChemCam instrument on Vera Rubin ridge (VRR) in Gale crater, Mars, are presented and compared with observations from similar rocks leading up to the ridge. VRR is a prominent ridge, flanking the central mound, Aeolis Mons, in Gale crater, Mars. The ridge attracted early attention because it displays strong iron‐oxide spectral signatures. Surprisingly, ChemCam data show that VRR rocks do not show an overall increase in iron abundance relative to the comparable bedrock analyzed for almost 300 m in elevation leading up to the ridge. While similar overall, some notable variations were observed on VRR relative to lower‐lying rocks. In particular, geochemical variations suggest a strong decrease in clay content on the ridge, above which, a notable enrichment in Mn is observed. No single geological process confidently explains all observations on the ridge. Rather, we think that VRR rocks underwent a series of interactions with groundwater that caused the rocks of VRR to become more resistant to erosion than their surroundings, thus emerging as a ridge as the rocks around them eroded. This likely implies that groundwater persisted in Gale crater even long after the disappearance of the ancient lake.
Key Points
A decrease in Li and Chemical Index of Alteration, reflecting clay mineral content, is observed across Vera Rubin ridge (VRR)
A Mn‐rich interval is observed stratigraphically above the decrease in clay mineral content on VRR
VRR likely resulted from increased induration from late‐stage fluid interactions long after the lake environment in Gale crater ceased
Objective
This article describes an easy‐to‐use ecodesign methodology developed and applied since 2014 by the L'Oréal Group to improve the sustainable performance of its new products without any ...compromise on their cosmetic efficacy.
Methods
Cosmetic products, after being used, are often discharged into the sewers and the aquatic compartment. This discharge is considered as dispersive and continuous. A consistent progress in reducing the environmental impact of cosmetic products can be achieved through focusing upon three strategic indicators: biodegradability, grey water footprint adapted for ecodesign (GWFE) and a global indicator, complementary to these two endpoints. Biodegradability represents the key process in the removal of organic ingredients from the environment. GWFE is defined herein as the theoretical volume of natural freshwater required to dilute a cosmetic formula after being used by the consumer, down to a concentration without any foreseeable toxic effects upon aquatic species. Finally, the complementary indicator highlights a possible alert on formula ingredients due to an unfavourable environmental profile based on hazard properties: for example Global Harmonization System/Classification, Labelling and Packaging (GHS/CLP) H410 classification or potential very persistent and very bioaccumulative (vPvB) classification.
Results
The ecodesign of a new cosmetic product can be a challenge as the cosmetic properties and quality of this new product should at least match the benchmark reference. As shown in the case studies described herein, new methodologies have been developed to maximize the biodegradability of cosmetic formulae, to minimize their GWFE and to limit the use of ingredients that present an unfavourable environmental profile, while reaching the highest standards in terms of cosmetic efficacy.
Conclusion
By applying these methodologies, highly biodegradable products (≥ 95% based on ingredient composition) have been developed and marketed, with a low GWFE. This new ecodesign approach shows that embedding sustainability in developing new cosmetic products can also open up new innovative opportunities.
Résumé
Objectif
Cet article décrit une méthodologie d’écoconception, facile à utiliser, développée et appliquée depuis 2014 par le groupe L'Oréal pour améliorer la performance durable de ses nouveaux produits, sans aucun compromis sur leur efficacité cosmétique.
Méthode
Les produits cosmétiques, après utilisation, sont souvent rejetés dans les égouts et le compartiment aquatique. Ce rejet est considéré comme dispersif et continu. Un progrès important dans la réduction de l'impact environnemental des produits cosmétiques peut être atteint en se concentrant sur trois indicateurs stratégiques: la biodégradabilité, l'empreinte eau grise adaptée à l’écoconception (GWFE) et un indicateur global complémentaire à ces deux paramètres. La biodégradabilité représente le processus clé dans l’élimination d'ingrédients biologiques de l'environnement. GWFE définit ici le volume théorique d'eau douce naturelle nécessaire pour diluer une formule cosmétique, après avoir été utilisée par le consommateur, à une concentration sans effets toxiques prévisibles sur les espèces. Enfin, l'indicateur complémentaire met en évidence une possible alerte sur les ingrédients de la formule en raison d'un profil environnemental défavorable basé sur les propriétés de danger: par exemple sur le Système Général Harmonisé / Classification, Étiquetage et Emballage (SGH / CLP), classification H410 ou potentiel classement très persistant et très bioaccumulable (vPvB).
Résultats
L’écoconception d'un nouveau produit cosmétique peut être un défi car les propriétés cosmétiques et la qualité de ce nouveau produit devraient au moins correspondre au produit de référence. Comme indiqué dans les études de cas décrites ici, de nouvelles méthodologies ont été développées pour maximiser la biodégradabilité des formules cosmétiques, minimiser leur GWFE et limiter l'utilisation des ingrédients présentant un profil environnemental défavorable, tout en atteignant les plus hautes exigences en termes d'efficacité cosmétique.
Conclusion
En appliquant ces méthodologies, des produits hautement biodégradables (≥ 95% selon la composition des ingrédients) ont été développés et commercialisés, avec une faible GWFE. Cette nouvelle approche d’écoconception montre que l'intégration de la soutenabilité dans le développement de nouveaux produits cosmétiques peut également ouvrir à de nouvelles opportunités d'innovations.
New methodologies have been developed to maximize the biodegradability of cosmetic formulae, to minimize their grey water footprint and to limit the use of ingredients that present an unfavourable environmental profile, while reaching the highest standards in terms of cosmetic efficacy.
This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons ...(informally known as Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray‐colored patches concentrated toward the upper elevations of VRR, and these gray patches also contain small, dark Fe‐rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric‐related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record.
Plain Language Summary
Vera Rubin ridge is a feature at the base of Mount Sharp with a distinct texture and topography. Orbiter observations showed hematite, a mineral that sometimes forms by chemical reactions in water environments, was present atop the ridge. The presence of both water and chemical activity suggested the area preserved a past habitable environment. In this paper, we detail how the Curiosity science team tested this and other orbital‐based hypotheses. Curiosity data suggested that most ridge rocks were lain down in an ancient lake and had similar compositions to other Mount Sharp rocks. Curiosity confirmed that hematite was present in the ridge but no more abundantly than elsewhere. Larger grain size or higher crystallinity probably account for the ridge's hematite being more visible from orbit. We conclude Vera Rubin ridge formed because groundwater recrystallized and hardened the rocks that now make up the ridge. Wind subsequently sculpted and eroded Mount Sharp, leaving the harder ridge rocks standing because they resisted erosion compared with surrounding rocks. The implication of these results is that liquid water was present at Mount Sharp for a very long time, not only when the crater held a lake but also much later, likely as groundwater.
Key Points
We summarize Curiosity's campaign at Vera Rubin ridge (Sols 1726–2302) and the high‐level results from articles in this special issue
Vera Rubin ridge formed when diagenesis hardened rocks along the base of Aeolis Mons; wind subsequently etched the feature into a ridge
Results add evidence for protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record
From Sol 750 to 1550, the Curiosity rover documented >100 m thick stack of fine-grained sedimentary rocks making up part of the Murray formation, at the base of Mt Sharp, Gale crater. Here, we use ...data collected by the ChemCam instrument to estimate the level of chemical weathering in these sedimentary rocks. Both the Chemical Index of Alteration (CIA) and the Weathering Index Scale (WIS) indicate a progressive increase in alteration up section, reaching values of CIA of 63 and WIS of 25%. The increase in CIA and WIS values is coupled with a decrease in calcium abundance, suggesting partial dissolution of Ca-bearing minerals (clinopyroxene and plagioclase). Mineralogy from the CheMin X-ray diffraction instrument indicates a decrease in mafic minerals compared with previously analyzed strata and a significant proportion of phyllosilicates consistent with this interpretation. Furthermore, these observations suggest that the sediments were predominantly altered in an open system, before or during their emplacement, contrasting with the rock-dominated conditions inferred in sedimentary deposits analyzed at Yellowknife Bay.
This paper provides an overview of the
rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons (informally known as ...Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature.
conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray-colored patches concentrated toward the upper elevations of VRR, and these gray patches also contain small, dark Fe-rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric-related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record.
The genotoxicity and/or toxicity of benzo(a)pyrene (BaP) were evaluated under different lighting conditions in larvae and embryos of the newt Pleurodeles waltl. Visible light alone (1,220 lx; 2.1 ...mW/cm2), UVA alone (250 microW/cm2), or BaP alone (500, 50, 25, 12.5 ppb) had no toxic effects on the larvae. Conversely, toxic effects were observed in animals exposed to BaP (500 ppb)+daylight, or BaP (> or = 25 ppb)+UVA. BaP solutions (50 or 12.5 ppb) were irradiated for 24 hr (Irr BaP) prior to being assayed in the dark. The genotoxicity of BaP (50 ppb) as evaluated in the micronucleus test (on day 8) was halved by its previous exposure to UVA, and was abolished at the lowest concentration (12.5 ppb). In other experiments, the larvae were exposed alternatively to BaP or Irr BaP (18 hr in the dark) and UVA (6 hr in water), every day for 8 days. All animals that had accumulated non-irradiated BaP (50 ppb) showed signs of severe toxicity, and 90% died before the end of the test. On the other hand, irradiated BaP (50 ppb) was 4-fold less toxic and half as genotoxic as non-irradiated BaP. In addition, exposure of the animals to UVA alone for 4 days prior to treatment with BaP did not affect the genotoxicity or toxicity of this hydrocarbon. In the dark, the embryotoxicity of BaP was markedly attenuated by the presence of the jelly coats (10% vs. 24%). With dejellied embryos, comparable mortality (24%) was observed after exposure to 25 ppb BaP for 54 or 312 hr. Although UVA alone did not affect growth of the embryos, the toxicity of BaP was enhanced by the combined action of the two agents together or in succession (BaP+UVA or BaP then UVA). Larvae were treated with an oil refinery effluent (EF). At the concentration employed (125 ml/l), EF was not found to be genotoxic in the dark. However, in animals exposed to both EF and UVA, there was a progressive increase in level of micronucleated erythrocytes with increasing duration of daily exposure to UVA (9, 15, 24 hr). Moreover, the genotoxic potential of irradiated EF+UVA was systematically below that of non-irradiated EF+UVA for all durations of exposure to ultraviolet light. Irradiation of this type of effluent might help reduce its harmful effects on aquatic species. Our results also suggest that metabolic activation is not necessary for hydrocarbons to induce toxic effects.
The genotoxic potential of various waste waters has been evaluated in a micronucleus test using amphibian larvae. Genotoxicity was detected after dilution, in waste water from tanneries and from ...various petrochemical industries. Further studies have shown that sample treatment used for in vitro testing may affect the genotoxic response. Sterilization by gamma irradiation lowered genotoxic activity. Furthermore, microfiltration of effluent and extraction of organic micropollutants on XAD-4 resins, lead to the preparation of extracts which are not fully representative of the initial water sample. Testing of concentrates, as required for in vitro studies, will limit the scope of a survey to that part of the organic matter that can be recovered by concentration techniques. Many of the problems encountered in in vitro genotoxicity studies of waters, may be circumvented with direct testing on aquatic organisms. Thus, there is no need to concentrate or sterilise a sample. The tests can be carried out with intact animals, thus taking into account uptake and elimination, internal transport and metabolism. Finally, in vivo test-systems, such as the Newt Micronucleus Test, are more relevant to eukaryotes than bacterial assays and are suitable to assess the real impact of genotoxins discharged in the aquatic environment.
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