Rare earth element enrichment in sedimentary phosphorites formed during the Precambrian-Cambrian transition,Southwest China

Numerous sedimentary phosphorites in Southwest China were formed around the Precambrian–Cambrian transition(PC–C),including the upper Ediacaran Doushantuo Formation and lower Cambrian Gezhongwu Formation.The Gezhongwu phosphorites in Zhijin exhibit marked rare earth element(REE)enrichment(>1000 ppm),and may represent new REE resources.Although the main characteristics of the Gezhongwu phosphorites have been well constrained,the REE enrichment mechanisms remain unclear.We undertook a comparative study of three typical sedimentary phosphorites with variable REE contents formed at the PC–C transition in central Guizhou Province,Southwest China.These include sections A and B of the Doushantuo phosphorites(560±8 Ma)from the Weng’an area(i.e.,WA-A and WA-B),and the Gezhongwu phosphorites(527±24 Ma)from the Zhijin area(ZJ).The phosphorites were investigated with state-of-the-art macroscale to nanoscale analytical techniques.In contrast to the extraordinary REE enrichment in the ZJ phosphorites(average RREE=1157 ppm),the phosphorites in WA-A(average RREE=234 ppm)and WA-B(average RREE=114 ppm)are REE-poor.Elemental mapping by laser ablation–inductively coupled plasma–mass spectrometry,along with transmission electron microscopy analyses,showed the REEs in the studied phosphorites are hosted in nanoscale francolites.The 87Sr/86Sr and Y/Ho ratios of the francolite grains indicate that greater terrigenous input may have led to more REE enrichment in the WA-A than WA-B phosphorites,but this cannot explain the extraordinary REE enrichment in the ZJ phosphorites.The F/P_(2)O_(5)values of the francolite grains in the ZJ phosphorites(~0.097)are higher than those in the WA-A(~0.084)and WA-B(~0.084)phosphorites,and the grain size of the francolite in the ZJ phosphorites(~89.9 nm)is larger than those in the WA-A(~56.6 nm)and WA-B(~57.4 nm)phosphorites,indicative of more intense reworking of the ZJ than WA phosphorites during early diagenesis.A plot of Nd concentration versus Ce/Ce^(*)reveals that lower sedimentation rates characterized the ZJ phosphorites.Therefore,intense sedimentary reworking during early diagenesis resulted in more REEs being sequestered by the marine phosphates from seawater and pore waters at a lower sedimentation rate,which resulted in the extraordinary REE enrichment in the ZJ phosphorites.Our findings highlight the multiple factors that controlled formation of sedimentary phosphorites around the PC–C transition(especially the intense reworking and redox conditions of the overlying seawater),and provide further insights into REE enrichment in sedimentary phosphorites worldwide.

The use of electrokinetics promises a sustainable mining future

Moving toward a zero-carbon economy is an ambitious goal of all human beings.Utilization of various metal resources plays a central role in such a transition.Rare earth elements(REEs),especially heavy REEs(HREEs),are crucial for the development of future green and zero-carbon economies due to their irreplaceable roles in many applications of renewable energy technologies;e.g.,solar panels,wind turbines,and hybrid vehicle batteries.Ion-adsorption rare earth deposits(IADs)are the primary repositories for HREEs and supply more than 95%of the global HREE demand.1 However,current mining technologies using excessive ammonium salts have caused devastating harm to the local environment while exhibiting a low recovery rate of REEs,a long mining period,and landslide risks.Since 2018,the adoption of ammonium salt-based techniques in REE mining has been prohibited,exacerbating the scarcity of REEs that could lead to disruptions of the supply chain.Moreover,metals are currently almost exclusively extracted from their ores via physical excavation or chemical leaching.These energy-intensive and environmentally damaging techniques remain among the foremost CO_(2) emitters.The mining industry is in desperate need of a new generation of mining technology.

TiO_2/Schwertmannite nanocomposites as superior co-catalysts in heterogeneous photo-Fenton process

The heterogeneous photo-Fenton reaction is an effective technique in combating organic contaminants for both soil and water remediation,and extensive studies have focused on enhancing its efficiency and reducing its costs.In this work,we developed novel photoFenton catalysts by simply milling commercially available TiO_2(P25)with Schwertmannite(Sh),a natural iron-oxyhydroxysulfate nanomineral.We expect that the photo-generated electrons from TiO_2could continuously migrate to Sh,which then could enhance the separation of electron-hole pairs on TiO_2and accelerate the reduction of Fe(III)to Fe(II)on Sh,leading to high degradation efficiency of the target organic contaminants.SEM and TEM results showed the distribution of TiO_2on Sh surface for the nanocomposites(TiO_2/Sh).Under simulated sunlight irradiation,the much higher content of Fe(II)was determined on TiO_2/Sh than on Sh via a common method in the iron ore,and the consumption of H_2O_2and the production of·OH were more significant in the TiO_2/Sh system than those in the TiO_2and Sh systems.These results well support our hypothesis that the photo-generated electrons could migrate from TiO_2to Sh on the composites,and can also explain the much higher degradation efficiency of Rhodamine B(RhB)in the TiO_2/Sh system.Besides,TiO_2/Sh had lower Fe dissolution as compared with Sh,and retained high catalytic stability after four repeated cycles.Above merits of the TiO_2/Sh composites,in combining with their simple synthesis method and low-cost property,indicated that they should have promising applications as heterogeneous photo-Fenton catalysts.

A new method to determine composition of sphalerite without secondary pollution based on CIELAB color space

Currently,most of the methods formineral materials analysis generate secondary pollution,which is detrimental to human health.For instance,traditionalmethods for sphalerite analysis in the zinc(Zn)smelting industry including chemical titration,atomic absorption spectrometry,and inductively coupled atomic emission spectroscopy.Colored indicators and toxic heavy metals are used in the analytical processes,causing severe pollution.For some methods,liquid is transformed into gaseous plasma,which is more dangerous to human health.Due to large quantities of sphalerite being used,secondary pollution cannot be ignored.This study proposes a green analysis method for the detection of sphalerite based on colorimetry,which does not generate secondary pollution.The results show that the strong substitution ability of iron(Fe)for Zn contributes to their inverse correlation in contents.The lattice parameters decrease with the increasing Fe content,resulting in a darker coloration.Here,key colorimetry parameters of L*,a*,and b*show clear linear correlations with the Zn and Fe contents.Compared with traditional approaches,this new method is environmental friendly with high sensitivity and accuracy.The relative error and relative standard deviation were less than 10%and 5%,respectively.This study provides a significant reference for nonpollution determination of other mineral materials.

Purification and Characterization of a New Ribosome Inactivating Protein from Cinchonaglycoside C-treated Tobacco Leaves

A new ribosome-inactivating protein （RIP） with a molecular weight of 31 kDa induced by Cinchonaglycoside C （1） designated CIP31, was isolated from tobacco leaves. Analysis of this protein sequence indicated that it belongs to the RIP family and it was distinct from the other plant RIPs reported previously at its N-terminal amino acid sequence. CIP31 can directly impair synthesis of coat protein （CP） of tobacco mosaic virus （TMV）, which resulted in inhibition of TMV long distance movement and multiplication in tobacco plants at concentrations of ng/mL. Furthermore, no toxicity was shown to the growth and fertility of the plants. CIP31 was synthesized only in the presence of Cinchonaglycoside C （1） and was independent of the salicylic acid （SA） signal pathway. We provided evidence for the SA-independent biological induction of resistance.

Interaction of polyhydroxy fullerenes with ferrihydrite：adsorption and aggregation

The rapid development of nanoscience and nanotechnology, with thousands types of nanomaterials being produced, will lead to various environmental impacts. Thus,understanding the behaviors and fate of these nanomaterials is essential. This study focused on the interaction between polyhydroxy fullerenes（PHF） and ferrihydrite（Fh）, a widespread iron（oxyhydr）oxide nanomineral and geosorbent. Our results showed that PHF were effectively adsorbed by Fh. The adsorption isotherm fitted the D-R model well, with an adsorption capacity of 67.1 mg/g. The adsorption mean free energy of 10.72 k J/mol suggested that PHF were chemisorbed on Fh. An increase in the solution p H and a decrease of the Fh surface zeta potential were observed after the adsorption of PHF on Fh; moreover, increasing initial solution p H led to a reduction of adsorption. The Fourier transform infrared spectra detected a red shift of C–O stretching from 1075 to 1062 cm-1 and a decrease of Fe–O bending, implying the interaction between PHF oxygenic functional groups and Fh surface hydroxyls. On the other hand, PHF affected the aggregation and reactivity of Fh by changing its surface physicochemical properties. Aggregation of PHF and Fh with individual particle sizes increasing from 2 nm to larger than 5 nm was measured by atomic force microscopy. The uniform distribution of C and Fe suggested that the aggregates of Fh were possibly bridged by PHF. Our results indicated that the interaction between PHF and Fh could evidently influence the migration of PHF, as well as the aggregation and reactivity of Fh.

Four New Indole Alkaloids from Neolamarckia cadamba

在 Neolamarckia cadamba 的叶子的 Phytochemical 调查导致了四新吲哚碱， spirocadambine (1 ) ， dehydraisodihydrocadambine (2 ) ， nitrocadambines A 和 B (3 和 4 ) 的隔离。结构和相对配置被 1D 和 2D NMR 系列建立。Spirocadambine (1 ) 代表包含吲哚 glucoalkaloids 的螺丝钉戒指的一种新类型。