Organic-rich sediments represent vital components of Earth's geochemical cycles, acting both as potential hydrocarbon and coal reservoirs and as unconventional archives for critical metals such as rare earth eleme...Organic-rich sediments represent vital components of Earth's geochemical cycles, acting both as potential hydrocarbon and coal reservoirs and as unconventional archives for critical metals such as rare earth elements(REEs). With the growing emphasis on clean energy technologies, the Cenozoic organic deposits of India have gained renewed significance;however, those from the southern state of Kerala remain understudied. This study investigates lignite and associated carbonaceous sediments from the Cheruvathur and Warkalli Formations using a multi-proxy approach integrating organic petrography,infrared spectroscopy, stable carbon isotopes, and REE geochemistry. The lignite exhibits huminite dominance with Type Ⅲ kerogen, deposited in a wet, mesotropic bog forest swamp under anoxic conditions. The mineral assemblage, dominated by kaolinite, quartz, illite, montmorillonite, feldspar,and pyrite/marcasite, reflects strong chemical alteration in a reducing environment. The δ^(13)C values(-25.1 to-27.3) indicate a C_(3) angiosperm source and deposition in tropical to subtropical swamp settings. REE patterns reveal LREE enrichment in carbonaceous shales and HREE enrichment in lignite,with distinct Ce, Eu, and Gd anomalies associated with provenance and redox conditions. The findings provide new insights into the paleoenvironmental evolution of Kerala's Cenozoic basins and highlight their potential as unconventional REE-bearing resources in the context of the global energy transition.展开更多
This study compares the environmental sustainability of five alternatives for the remediation of marine sediments of one of the most polluted coastal sites in Europe(Bagnoli-Coroglio bay,Mediterranean Sea),using the L...This study compares the environmental sustainability of five alternatives for the remediation of marine sediments of one of the most polluted coastal sites in Europe(Bagnoli-Coroglio bay,Mediterranean Sea),using the Life Cycle Assessment(LCA)methodology.The treatments are either in-situ or exsitu,the latter requiring an initial dredging to transport the contaminated sediments to the management site.More in detail,four ex-situ remediation technologies based on landfilling,bioremediation,electrokinetic technique and soil washing were identified.These technologies are compared to an in-situ strategy currently under validation for enhancing bioremediation of the polluted sediments of the Bagnoli-Coroglio site.Our results indicate that the disposal in landfilling site is the worst option in most categories(e.g.,650 kg CO_(2) eq./t of treated sediment,considering the nearest landfilling site),followed by the bioremediation,mainly due to the high energy demand.Electrokinetic remediation,soil washing,and innovative in-situ technology represent the most sustainable options.In particular,the new in-situ technology appears to be the least impacting in all categories(e.g.,54 kg CO_(2) eq./t of treated sediment),although it is expected to require longer treatment time(estimated up to 12 months based on its potential efficiency).It can reduce the impact on climate change more than 12 times compared to the disposal and 7 times compared to bioremediation in addition to the possibility to avoid/reduce the dredging operations and the consequent dispersion of pollutants.The results open relevant perspectives towards more eco-sustainable and costly effective actions for the reclamation of contaminated marine sediments.展开更多
Liquid-solid phase transfer promotes the interaction of perfluoroalkyl acids(PFAAs)with the microbial system of river sediments,which may affect the environmental behavior of antibiotic resistance genes(ARGs)contained...Liquid-solid phase transfer promotes the interaction of perfluoroalkyl acids(PFAAs)with the microbial system of river sediments,which may affect the environmental behavior of antibiotic resistance genes(ARGs)contained in benthic environments.Sediments collected from the receiving water of the largest fluoropolymer production facility in China were analyzed to investigate the impact of PFAAs on microbial communities and ARG profiles.The main contributors to the PFAAs were perfluorooctanoic acid and perfluorobutanoic acid,whose proportions(86.9%-93.4%)in the downstream surface sediments affected by industrial effluents were significantly higher than in the corresponding upstream samples(53.3%).A reduction in microbial diversity and richness was observed in the presence of high concentrations of PFAAs at the downstream sites.144 ARG subtypes,including three high-risk subtypes(bacA,aac(6′)-I and aadA),were identified in sediment samples.The discharge of fluorochemical effluents also results in a reduction of ARG diversity at subtype level.PFAAs exert a pronounced influence on the profile of ARGs in sediment.PFAAs and water quality parameters(e.g.pH and total phosphorus)were key drivers of the microbial community composition in the sediment.The regulation of microbial communities by PFAAs may represent an important pathway by which these compounds affect ARG profiles.展开更多
Aeolian sediments in the eastern Qinghai Lake region,China serve as sensitive paleoclimate archives,offering an ideal window into past environmental conditions.This study investigated the Dashuitang(QDST)profile in th...Aeolian sediments in the eastern Qinghai Lake region,China serve as sensitive paleoclimate archives,offering an ideal window into past environmental conditions.This study investigated the Dashuitang(QDST)profile in the eastern Qinghai Lake region by integrating sediment grain size,chroma,and magnetic susceptibility(MS)proxies to reconstruct the regional environmental evolution since the Last Glacial Interstadial and to investigate its relationship with the water level fluctuations of Qinghai Lake.Grain size end-member modeling analysis(EMMA)identified three end-members:end-member 1(EM1)represented fine-grained material transported over longer distances through mixing processes,which could reveal the regional moisture conditions;end-member 2(EM2)primarily consisted of coarse-grained material from nearby sources transported via saltation or creep,indicating the intensity of the winter monsoon;and end-member 3(EM3)mainly reflected deposition from dust storm events controlled by regional low-altitude wind systems.In addition,the regional environmental sequence demonstrated coherence with other records,collectively elucidating the sub-orbital-scale dynamics of the Asian monsoon.The environmental sequence was divided into four principal phases on the basis of sedimentary characteristics and climatic responses:the late Last Glacial Interstadial,Last Glacial Maximum,Last Deglaciation,and Holocene phases.Additionally,the results of this study revealed that there is a close linkage between desertification and lake evolution in the eastern Qinghai Lake region.Since the Last Glacial Interstadial,desertification and lake evolution processes have generally exhibited a trade-off relationship,wherein lake level decline and desert expansion exhibited a direct positive feedback.However,during the early period of the Late Holocene(approximately 2.80–1.50 ka BP),a synergistic response pattern emerged,characterized by relatively high lake levels alongside moderate desert expansion,reflecting an asymmetric decoupling mechanism between the hydrological processes and aeolian dynamics during climatic transition periods.This study provides important insights for predicting the future evolution trends of lake-desert systems under climate change.展开更多
Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications...Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications.Seabed sediment classification is one of the main contents of seabed habitat mapping.In response to the impact of remote sensing imaging quality and the limitations of acoustic measurement range,where a single data source does not fully reflect the substrate type,we proposed a high-precision seabed habitat sediment classification method that integrates data from multiple sources.Based on WorldView-2 multi-spectral remote sensing image data and multibeam bathymetry data,constructed a random forests(RF)classifier with optimal feature selection.A seabed sediment classification experiment integrating optical remote sensing and acoustic remote sensing data was carried out in the shallow water area of Wuzhizhou Island,Hainan,South China.Different seabed sediment types,such as sand,seagrass,and coral reefs were effectively identified,with an overall classification accuracy of 92%.Experimental results show that RF matrix optimized by fusing multi-source remote sensing data for feature selection were better than the classification results of simple combinations of data sources,which improved the accuracy of seabed sediment classification.Therefore,the method proposed in this paper can be effectively applied to high-precision seabed sediment classification and habitat mapping around islands and reefs.展开更多
Obtaining high-quality 10000-meter-deep seafloor sediment samples is the prerequisite and foundation for conducting deep-sea geological and environmental scientific research.The bottom structure of the deep seafloor i...Obtaining high-quality 10000-meter-deep seafloor sediment samples is the prerequisite and foundation for conducting deep-sea geological and environmental scientific research.The bottom structure of the deep seafloor is complex,and the physical and mechanical properties and disturbance resistance of sediments of different lithologies vary greatly,so the sediment sampler inevitably disturbs the sediments during the sampling process and affects the quality of the sediment samples.A new type of deep-sea sediment pressure retaining sampler is introduced,the force state and elastic–plastic state of the sampler destroying sediments are analyzed,the radial disturbance model of sediment coring based on the spherical cavity expansion theory is established,and the radius of sediments undergoing plastic deformation around the spherical holes is used as an index for evaluating the radial disturbance of sediments.The distribution of stress and strain fields in the sediments during the expansion of the spherical cavity and the influencing factors of the radius of the radially disturbed region(plastic region)are analyzed using an arithmetic example,and the influence law is analyzed.A sediment disturbance experimental platform was built indoors to simulate the sediment coring process.The radial stress field and pore water pressure of the sediment during the coring process were monitored by sensors arranged inside the sediment,and the results of indoor tests verified the correctness of the perturbation theory model.The sampler was carried aboard the deep-sea manned submersible FENDOUZHE and conducted on-site tests at depths of 9298.4 and 9142.8 m in the Kuril-Kamchatka Trench.Pressure-preserved sediment samples were retrieved,with preservation rates of 94.21%and 92.02%,respectively,which are much higher than the current technical indicator of 80%of pressure-holding ratio for deep-sea sediments.The retrieved sediments have obvious stratification characteristics and little disturbance.展开更多
The Malacca Strait(MS)is a vital conduit for the exchange of water and sediment between the Indian Ocean and the Pacific Ocean,serving as a critical‘gateway'for sediment transport.Here,we present the geochemical ...The Malacca Strait(MS)is a vital conduit for the exchange of water and sediment between the Indian Ocean and the Pacific Ocean,serving as a critical‘gateway'for sediment transport.Here,we present the geochemical characteristics of surface sediments in the MS to elucidate the relationship between terrestrial material inputs and modern oceanic dynamic transport processes in the strait.The results reveal that the MS can be divided into three distinct geochemical provinces.ProvinceⅠ,located in the central region of the strait,is characterized by residual deposits.The preservation of these residual deposits can be attributed to the restricted sediment supply and the relatively weaker modern sedimentary hydrodynamic conditions.ProvinceⅡ,situated to the north of ProvinceⅠ,exhibits provenance differences between its southern and northern regions.The northern region is primarily supplied by sediments originating from the eastern shelf of the Andaman Sea,whereas sediments derived from Sumatra and the Sunda Shelf are predominantly deposited in the southern part of ProvinceⅡ.ProvinceⅢextends along the western coast of the Malaysian Peninsula,with sediments primarily sourced from the Malaysian Peninsula and the Sunda Shelf,while contributions from Sumatra and the eastern shelf of the Andaman Sea are negligible.River sediments from the Malaysian Peninsula and Sumatra are transported northwestward along their respective coasts by prevailing currents,which also facilitate the transportation of Sunda Shelf sediments within the strait,while sediments from the eastern shelf of the Andaman Sea are delivered to the MS via southward coastal currents during the southwest monsoon period.The southward currents and well-developed eddies potentially impede the northward transport of sediments from the Sunda Shelf and restrict the distribution of Andaman Sea sediments within the strait.This study substantially enhances the understanding of source-to-sink processes in the Indo-Pacific region.展开更多
Fluoroquinolones(FQs)have the propensity to accumulate in sediments once introduction into aquatic envi-ronments,thereby posing potential threats to benthic organisms,yet the ecotoxicity of sediment-associated FQs rem...Fluoroquinolones(FQs)have the propensity to accumulate in sediments once introduction into aquatic envi-ronments,thereby posing potential threats to benthic organisms,yet the ecotoxicity of sediment-associated FQs remains unclear.In this study,the toxicokinetics and responses of multiple biomarkers in Bellamya aeruginosa,exposed to the three commonly used FQs(norfloxacin,NOR;ciprofloxacin,CIP;levofloxacin,LEVO)at envi-ronmentally relevant concentrations were investigated under sediment exposure scenario.The results revealed that FQs were effectively ingested by B.aeruginosa from sediments,CIP showing the highest bioaccumulation(180.59μg/kg),followed by NOR(74.49μg/kg)and LEVO(36.02μg/kg).CIP exhibiting a highest uptake rate constant(Ks)(4.64 g/(g·day))and the lowest elimination rate constant(K_(e))(0.05 g/(g·day)).The descending order of biological half-life is as follows:CIP(13.62 days),LEVO(8.14 days),and NOR(6.83 days).NOR induced the activity of superoxide dismutase,catalase,and glutathione-S-transferase while CIP and LEVO depressed their activities and increased malondialdehyde content,indicating a more pronounced oxidative damage to B.aerug-inosa caused by CIP and LEVO than NOR.Furthermore,all three FQs were found to induce DNA damage and elevate acetylcholinesterase activity,suggesting distinct genotoxic and neurotoxic effects.Interestingly,despite its low bioaccumulation potential,LEVO exhibited high toxicity towards B.aeruginosa.These findings enhance our understanding of the ecotoxicity of FQs in sediments,providing further evidence of their potential ecological risks.展开更多
Organic phosphorus(OP)constitutes an important fraction of total phosphorus in lake sediments,with its mobility being influenced by mineralization and transformation of organic carbon(OC).OP and OC co-exist in various...Organic phosphorus(OP)constitutes an important fraction of total phosphorus in lake sediments,with its mobility being influenced by mineralization and transformation of organic carbon(OC).OP and OC co-exist in various forms in the environment,thus a thorough investigation on the impact of OC fractions on the release of OP in sediments should be comprehensively carried out.This study determined the chemical forms of OP and OC in the sediments over four seasons in Lake Taihu and found temporal and spatial variations in their concentrations.The concentration of total OP and total OC ranged from 133 to 348 mg/kg and 4.77 to 21.19 mg/kg,respectively.Correlation between chemical fractions of OP and OC also revealed that Na OH-extracted OP,and fulvic acid-bound and humic acid-bound OP were positively correlated with humic-OC and hot hydrolysis-OC.These results suggest that the algal-derived OC degradation and mineralization may enhance OP mineralization,converting stable or moderately active OP into active forms or inorganic phosphorus under cyanobacterial bloom.This study provides insight and guiding support for investigating the impact of organic matter components on the transformation of OP after cyanobacterial degradation in eutrophic lakes.展开更多
The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sed...The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.展开更多
Plastic pollution and microplastics in sediments are a growing concern for marine ecosystems worldwide.We examined the vertical distribution and properties of microplastics in beach sediments of Xuwen Coral Reef Natio...Plastic pollution and microplastics in sediments are a growing concern for marine ecosystems worldwide.We examined the vertical distribution and properties of microplastics in beach sediments of Xuwen Coral Reef National Nature Reserve,in Leizhou Peninsula,Zhanjiang,China.Sediment samples were taken in seven locations at 5-cm intervals from the surface to a depth of 30 cm.The vertical distribution of microplastic particles ranged from 0 to 1340 particles per kg on average of 119.05particles per kg.The most prevalent material was fibers(76%),followed by film(12%),fragments(11.2%),and foam(0.8%).The microplastics in size of 1-2 mm constituted the largest percentage(40%)of the total,followed by those in size of<1 mm(26.4%),2-3 mm(21.2%),3-4 mm(9.6%),and 4-5 mm(2.81%).Site S1 observed maximum sizes between 1 and 2 mm,S2 reported higher availability of microplastics with sizes ranging from 0.3 to 1 mm.Six different types of polymers were identified in the investigation,and mostly were polyethylene(PE)and polypropylene(PP).In general,the observation of microplastics in deeper sediments indicates that they have the ability to last for prolonged periods in the marine environment,which may present long-term hazards to benthic creatures.In conclusion,the discovery of microplastics in deep layers of coastal sediments highlights the necessity of minimizing plastic waste and enhancing management strategies to safeguard marine environments.展开更多
Microplastic(MP)contamination is becoming a major worldwide concern,affecting terrestrial and aquatic ecosystems.This study investigated the source,distribution,and abundance of MPs in sediments from Dongshan Bay,Fuji...Microplastic(MP)contamination is becoming a major worldwide concern,affecting terrestrial and aquatic ecosystems.This study investigated the source,distribution,and abundance of MPs in sediments from Dongshan Bay,Fujian,South China,emphasizing particularly the coastline region's susceptibility to tidal impacts in four study sites.The concentrations of MPs in the sediments in the four sites were high from 7.4 to 283.1 items/kg(dry weight).There were notable differences in abundance between the locations and tide levels.Tides influenced the distribution of MPs greatly;however,the estuary areas showed greater MPs abundance during high tide,due possibly to enhanced water turbulence and riverine inputs.Low tide indicated higher concentrations in coastal locations owing to accumulation.Popular varieties,including nylon,polypropylene,and polyethylene,were identified by polymer research,pointing to the origins from fishing,packaging,and mariculture industries.Potential sources were determined using the PCA-K-means statistical analysis,by linking the origins of MPs to domestic activities,fishing,mariculturing,shipping,and packing.Fishing and packing were shown in the Sankey diagram as the two main sources,but their effects varied with research locations and tidal regimes.This study clarified the intricate dynamics of MPs pollution,highlighting the impact of tides on its dispersal and the variety of sources that contribute to this widespread environmental problem in coastal areas.展开更多
Industrial activities have contributed so much to the pollution of water bodies and these pollutions have adversely affected the aquatic ecosystem.This study aimed to investigate the ecological risk evaluation of heav...Industrial activities have contributed so much to the pollution of water bodies and these pollutions have adversely affected the aquatic ecosystem.This study aimed to investigate the ecological risk evaluation of heavy metal accumulation in Aba River bottom sediments:implications for soap and detergent industry wastewater management.Varian AA240 Atomic absorption spectrometer was used to analyse heavy metals.Individual and complex ecological indices were used to evaluate heavy metal contamination in bottom sediments.According to the results,the heavy metal properties of the wastewater indicated that Fe,Pb,Cd,Cr and Cu mean concentration values were higher than the World Health Organization(WHO)and the National Environmental Standards and Regulations Enforcement Agency(NESREA)permissible limits.Heavy metal properties of the surface water in Aba River(dry seasons)showed that Pb,Cd,Cu,Mn,Fe,and Cr,mean concentrations were above the NESREA,WHO and U.S.Environmental Protection Agency(USEPA)permissible limits.Heavy metal properties of the bottom sediments of Aba River(wet and dry season)showed that Pb,Cd,and Fe mean concentrations were significantly higher than the NESREA,WHO and USEPA permissible limits.The heavy metal contamination factor(CF)of sediments obtained from Aba River during the wet and dry season was low and the CFs of each of the assayed heavy metals were less than 1(CD<1).This also signifies the existence of a low contamination in the sediments of the course streams of Aba River during wet and dry season.The pollution load index(PLI)values of Aba River(sediment)indicated that there is no metal pollution at PLI<1 in the sampled sediments.The potential ecological risk index(RI)of Aba River was less than 150(RI<150)indicating a low ecological RI.Abatement of pollutants in the wastewater to permissible concentrations required for natural environment protection is needed.展开更多
Elemental concentrations of the siliciclastic sediments from a sedimentary basin provide clues on paleo-weathering,paleoclimate,provenance,and tectonic setting of the basin.Records for Permo-Triassic mass extinction a...Elemental concentrations of the siliciclastic sediments from a sedimentary basin provide clues on paleo-weathering,paleoclimate,provenance,and tectonic setting of the basin.Records for Permo-Triassic mass extinction and climatic fluctuations are commonly traced from the sediments in the Gondwana basins.Nevertheless,our understanding on sedimentation,provenance,and regional tectonics of the Raniganj Basin,a Gondwana basin in the eastern India is poor.Minerals including clay particles and major and trace element concentrations of the siliciclastic sediments from different formations of the Raniganj Basin have been studied to establish the paleo-weathering,paleoclimate,provenance,and tectonic settings of the basin.This study suggests that the Talchir Formation experienced cold and dry climatic conditions at the sediment source area,while the Barakar,Raniganj,and Panchet formations had prevailing semiarid climates.The sources of the siliciclastic sediments are from the felsic rocks of the Chotanagpur Granite Gneissic Complex(CGGC).Further,the geochemical results suggest a rift-like(passive)tectonic setting for the Raniganj Basin,while few samples represent the collision tectonic setting of the basement CGGC,formed due to collision of major Indian blocks during the Paleo-Neoproterozoic time.展开更多
This study investigates the distribution,geochemical behavior,and potential anthropogenic influences of rare earth elements(REEs)in the surface sediments of Qinghai Lake,the largest saline lake in China.A total of 36 ...This study investigates the distribution,geochemical behavior,and potential anthropogenic influences of rare earth elements(REEs)in the surface sediments of Qinghai Lake,the largest saline lake in China.A total of 36 surface sediment samples were analyzed for REE concentrations with a combination of self-organizing maps(SOM)and positive matrix factorization(PMF).Results indicate distinct enrichment patterns,with light REEs(LREEs)exhibiting higher concentrations than heavy REEs(HREEs),reflecting natural abundances and geochemical behaviors.The minimum value was found in Lu as low as 0.091 mg/kg,and the maximum concentration was exhibited in Ce at 78.877 mg/kg.Geoaccumulation index(I_(geo))analysis reveals minor to moderate enrichment of specific REEs of Sm and Nd,suggesting possible localized anthropogenic inputs,particularly near river mouths.Spatial analysis using inverse distance weighting(IDW)and self-organizing maps(SOM)highlights significant correlations between REE distributions and riverine inputs,underscoring fluvial transport's role in sedimentary REE dynamics.PMF identifies mixed natural and anthropogenic sources,with agricultural and industrial activities contributing to elevated REE levels in sediment.These findings provide critical insights into the geochemical behavior of REEs in saline lake systems and off er a foundation for pollution control and sustainable resource management in sensitive environments like Qinghai Lake.展开更多
The sediments of crater lakes are one of the ideal archives for high-resolution paleoenvironmental reconstruction.This paper presents sedimentary records of 21 crater lakes in monsoonal China and systematically discus...The sediments of crater lakes are one of the ideal archives for high-resolution paleoenvironmental reconstruction.This paper presents sedimentary records of 21 crater lakes in monsoonal China and systematically discusses the geographical distribution and formation ages of these crater lakes.Sediment provenance of the crater lakes and its influencing factors were analyzed,and paleoenvironmental sequences and human activities records on different timescales reconstructed by crater lake sediments in monsoonal China were reviewed.The following points are highlighted:(1)Crater lakes in monsoonal China have been shown to preserve continuous long-time sediments that can exceed even 400 ka,although the chronology of some sediments in the southern part is debated and there were currently fewer long time records from the northern part;(2)the sediment provenance of crater lakes in northern China(e.g.,aeolian inputs)was different from that in the south(e.g.,the volcanic-lake rim),due to the different location and deposition conditions of crater lakes;(3)crater lake sediments have been used to reconstruct the history of climate changes on different timescales,but reconstruction studies of glacial-interglacial and decadal-annual scale records and studies of spatial comparisons of records on different timescales still need to be strengthened;(4)the anthropogenic signals,which include cultivation,logging,and industrial activity,are well documented in crater lake sediments from different areas and can therefore provide key evidence for the study of the Anthropocene.展开更多
We measured the content of six heavy-metal elements(Co,Cu,Zn,As,Cd,Pb)in 72 lake surface-sediment samples from the Xizang Autonomous Region(referred to as Xizang)of China,and calculated four indices:enrichment factor(...We measured the content of six heavy-metal elements(Co,Cu,Zn,As,Cd,Pb)in 72 lake surface-sediment samples from the Xizang Autonomous Region(referred to as Xizang)of China,and calculated four indices:enrichment factor(EF),geo-accumulation index(Igeo),pollution load index(PLI),and a comprehensive potential ecological risk index(RI)to explore the differences in the accumulation and the major sources of heavy metals,and to reveal the role of human activities in the ecological environment of high-elevation cold regions.Results show that the heavy-metal contents in lake surface sediment samples in eastern Xizang are much higher than those in central and western areas,and are also higher than the background value of surface soils.Their distribution can be related to regional sources of heavy metals:natural parent material(western Xizang),agriculture(eastern Xizang),mining-related industrial sources(central Xizang),and degree of development of road network(all of Xizang).The majority of lakes in Xizang have a relatively low risk of ecological harm,but there are notable regional peculiarities in the element content and evaluation indices and the lakes in eastern Xizang are at higher risk than those in central and western parts.Lakes at higher ecological risk(such as Lake Butuo(Lake 71)and Samu Co(Lake 68)),remind us that the potential influence of heavy-metal enrichment on lake sediments and aquatic plants should not be overlooked.展开更多
The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study cruci...The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study crucial for understanding environmental changes in the region.Despite its importance,research on the Shichuanhe River basin has thus far been primarily focused on riverbank construction,with limited exploration of its sediment characteristics.Although river sediments hold potential for guiding agricultural practices in the area,comprehensive studies on their composition and provenance remain scarce.To address this gap,a systematic sediment sampling campaign was conducted in the lower reaches of the Shichuanhe River,and detailed mineralogical analyses were performed.The results show that the sediment is predominantly composed of detrital quartz and feldspar(albite and orthoclase),with heavy minerals constituting approximately 10%–12%of the total sediment volume.The analysis of the heavy mineral assemblage reveals an absence of signifi cant contributions from igneous rocks in the sedimentary profi le.Furthermore,the distribution patterns of major,trace,and rare-earth elements in the Shichuanhe River’s argillaceous sediments exhibit similarities to those found in the Weihe River’s sediments.Elemental fractionation patterns suggest that the Shichuanhe River sediments are primarily derived from Loess Plateau sediments,aligning with fi ndings from both the Weihe River and the middle reaches of the Yellow River.展开更多
Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear streng...Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear strength under varying dissociation conditions have not been thoroughly investigated. To this end,a series of triaxial compression tests were first carried out on sediments with varying initial hydratesaturations along dissociation pathways. Combining measured data with microscale analysis, the underlyingmechanism for the evolution of shear strength in hydrate-bearing sediment was studied undervarying partial dissociation pathways. Moreover, a shear strength model for hydrate-bearing sedimentwas proposed, taking into account the hydrate saturation and the unhydrated water content. Apart fromthe parameters derived from the hydrate characteristic curve, only one additional model parameter isrequired. The proposed model was validated using measured data on hydrate sediments. The resultsindicate that the proposed model can effectively capture the shear strength behavior of hydrate-bearingsediment under varying dissociation paths. Finally, a sensitivity analysis of the model parameters wasconducted to characterize the proposed model.展开更多
In the long-term exploitation of natural gas hydrate,the stress change intensifies the creep effect and leads to the destruction of pore structures,which makes it difficult to predict the permeability of hydrate reser...In the long-term exploitation of natural gas hydrate,the stress change intensifies the creep effect and leads to the destruction of pore structures,which makes it difficult to predict the permeability of hydrate reservoir.Although permeability is crucial to optimize gas recovery for gas hydrate reservoirs,until now,accurately modeling the permeability of hydrate-bearing clayey-silty sediments during the creep process remains a significant challenge.In this study,by combining the nonlinear fractional-order constitutive model and the Kozeny-Carman(KC)equation,a novel creep model for predicting the permeability of hydrate-bearing clayey-silty sediments has been proposed.In addition,experimental tests have been conducted to validate the derived model.The proposed model is further validated against other available test data.When the yield function F<0,the permeability decreases gradually due to the shrinkage of pore space.However,when the yield function F≥0,the penetrating damage bands will be generated.Results show that,once the model parameters are determined appropriately by fitting the test data,the model can also be used to predict permeability under any other stress conditions.This study has a certain guiding significance for elucidating the permeability evolution mechanisms of hydrate-bearing clayey-silty sediments during the extraction of marine gas hydrates.展开更多
文摘Organic-rich sediments represent vital components of Earth's geochemical cycles, acting both as potential hydrocarbon and coal reservoirs and as unconventional archives for critical metals such as rare earth elements(REEs). With the growing emphasis on clean energy technologies, the Cenozoic organic deposits of India have gained renewed significance;however, those from the southern state of Kerala remain understudied. This study investigates lignite and associated carbonaceous sediments from the Cheruvathur and Warkalli Formations using a multi-proxy approach integrating organic petrography,infrared spectroscopy, stable carbon isotopes, and REE geochemistry. The lignite exhibits huminite dominance with Type Ⅲ kerogen, deposited in a wet, mesotropic bog forest swamp under anoxic conditions. The mineral assemblage, dominated by kaolinite, quartz, illite, montmorillonite, feldspar,and pyrite/marcasite, reflects strong chemical alteration in a reducing environment. The δ^(13)C values(-25.1 to-27.3) indicate a C_(3) angiosperm source and deposition in tropical to subtropical swamp settings. REE patterns reveal LREE enrichment in carbonaceous shales and HREE enrichment in lignite,with distinct Ce, Eu, and Gd anomalies associated with provenance and redox conditions. The findings provide new insights into the paleoenvironmental evolution of Kerala's Cenozoic basins and highlight their potential as unconventional REE-bearing resources in the context of the global energy transition.
基金support in the literature analysis.This study has been carried out in the framework of the project funded by EU entitled“Bioremediation of contaminated sediments in coastal areas of exindustrial sites-LIFE SEDREMED”(No.LIFE20 ENV/IT/000572).
文摘This study compares the environmental sustainability of five alternatives for the remediation of marine sediments of one of the most polluted coastal sites in Europe(Bagnoli-Coroglio bay,Mediterranean Sea),using the Life Cycle Assessment(LCA)methodology.The treatments are either in-situ or exsitu,the latter requiring an initial dredging to transport the contaminated sediments to the management site.More in detail,four ex-situ remediation technologies based on landfilling,bioremediation,electrokinetic technique and soil washing were identified.These technologies are compared to an in-situ strategy currently under validation for enhancing bioremediation of the polluted sediments of the Bagnoli-Coroglio site.Our results indicate that the disposal in landfilling site is the worst option in most categories(e.g.,650 kg CO_(2) eq./t of treated sediment,considering the nearest landfilling site),followed by the bioremediation,mainly due to the high energy demand.Electrokinetic remediation,soil washing,and innovative in-situ technology represent the most sustainable options.In particular,the new in-situ technology appears to be the least impacting in all categories(e.g.,54 kg CO_(2) eq./t of treated sediment),although it is expected to require longer treatment time(estimated up to 12 months based on its potential efficiency).It can reduce the impact on climate change more than 12 times compared to the disposal and 7 times compared to bioremediation in addition to the possibility to avoid/reduce the dredging operations and the consequent dispersion of pollutants.The results open relevant perspectives towards more eco-sustainable and costly effective actions for the reclamation of contaminated marine sediments.
基金supported by the National Key Research and Develop-ment Program of China(No.2021YFC3200805)the National Natu-ral Science Foundation of China(Nos.52325001 and 52170009).
文摘Liquid-solid phase transfer promotes the interaction of perfluoroalkyl acids(PFAAs)with the microbial system of river sediments,which may affect the environmental behavior of antibiotic resistance genes(ARGs)contained in benthic environments.Sediments collected from the receiving water of the largest fluoropolymer production facility in China were analyzed to investigate the impact of PFAAs on microbial communities and ARG profiles.The main contributors to the PFAAs were perfluorooctanoic acid and perfluorobutanoic acid,whose proportions(86.9%-93.4%)in the downstream surface sediments affected by industrial effluents were significantly higher than in the corresponding upstream samples(53.3%).A reduction in microbial diversity and richness was observed in the presence of high concentrations of PFAAs at the downstream sites.144 ARG subtypes,including three high-risk subtypes(bacA,aac(6′)-I and aadA),were identified in sediment samples.The discharge of fluorochemical effluents also results in a reduction of ARG diversity at subtype level.PFAAs exert a pronounced influence on the profile of ARGs in sediment.PFAAs and water quality parameters(e.g.pH and total phosphorus)were key drivers of the microbial community composition in the sediment.The regulation of microbial communities by PFAAs may represent an important pathway by which these compounds affect ARG profiles.
基金supported by the National Natural Science Foundation of China(41171018,41161036).
文摘Aeolian sediments in the eastern Qinghai Lake region,China serve as sensitive paleoclimate archives,offering an ideal window into past environmental conditions.This study investigated the Dashuitang(QDST)profile in the eastern Qinghai Lake region by integrating sediment grain size,chroma,and magnetic susceptibility(MS)proxies to reconstruct the regional environmental evolution since the Last Glacial Interstadial and to investigate its relationship with the water level fluctuations of Qinghai Lake.Grain size end-member modeling analysis(EMMA)identified three end-members:end-member 1(EM1)represented fine-grained material transported over longer distances through mixing processes,which could reveal the regional moisture conditions;end-member 2(EM2)primarily consisted of coarse-grained material from nearby sources transported via saltation or creep,indicating the intensity of the winter monsoon;and end-member 3(EM3)mainly reflected deposition from dust storm events controlled by regional low-altitude wind systems.In addition,the regional environmental sequence demonstrated coherence with other records,collectively elucidating the sub-orbital-scale dynamics of the Asian monsoon.The environmental sequence was divided into four principal phases on the basis of sedimentary characteristics and climatic responses:the late Last Glacial Interstadial,Last Glacial Maximum,Last Deglaciation,and Holocene phases.Additionally,the results of this study revealed that there is a close linkage between desertification and lake evolution in the eastern Qinghai Lake region.Since the Last Glacial Interstadial,desertification and lake evolution processes have generally exhibited a trade-off relationship,wherein lake level decline and desert expansion exhibited a direct positive feedback.However,during the early period of the Late Holocene(approximately 2.80–1.50 ka BP),a synergistic response pattern emerged,characterized by relatively high lake levels alongside moderate desert expansion,reflecting an asymmetric decoupling mechanism between the hydrological processes and aeolian dynamics during climatic transition periods.This study provides important insights for predicting the future evolution trends of lake-desert systems under climate change.
基金Supported by the National Natural Science Foundation of China(Nos.42376185,41876111)the Shandong Provincial Natural Science Foundation(No.ZR2023MD073)。
文摘Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications.Seabed sediment classification is one of the main contents of seabed habitat mapping.In response to the impact of remote sensing imaging quality and the limitations of acoustic measurement range,where a single data source does not fully reflect the substrate type,we proposed a high-precision seabed habitat sediment classification method that integrates data from multiple sources.Based on WorldView-2 multi-spectral remote sensing image data and multibeam bathymetry data,constructed a random forests(RF)classifier with optimal feature selection.A seabed sediment classification experiment integrating optical remote sensing and acoustic remote sensing data was carried out in the shallow water area of Wuzhizhou Island,Hainan,South China.Different seabed sediment types,such as sand,seagrass,and coral reefs were effectively identified,with an overall classification accuracy of 92%.Experimental results show that RF matrix optimized by fusing multi-source remote sensing data for feature selection were better than the classification results of simple combinations of data sources,which improved the accuracy of seabed sediment classification.Therefore,the method proposed in this paper can be effectively applied to high-precision seabed sediment classification and habitat mapping around islands and reefs.
基金supported by the National Key Research and Development Program of China(Nos.2023YFC2809304 and 2022YFC2805904).
文摘Obtaining high-quality 10000-meter-deep seafloor sediment samples is the prerequisite and foundation for conducting deep-sea geological and environmental scientific research.The bottom structure of the deep seafloor is complex,and the physical and mechanical properties and disturbance resistance of sediments of different lithologies vary greatly,so the sediment sampler inevitably disturbs the sediments during the sampling process and affects the quality of the sediment samples.A new type of deep-sea sediment pressure retaining sampler is introduced,the force state and elastic–plastic state of the sampler destroying sediments are analyzed,the radial disturbance model of sediment coring based on the spherical cavity expansion theory is established,and the radius of sediments undergoing plastic deformation around the spherical holes is used as an index for evaluating the radial disturbance of sediments.The distribution of stress and strain fields in the sediments during the expansion of the spherical cavity and the influencing factors of the radius of the radially disturbed region(plastic region)are analyzed using an arithmetic example,and the influence law is analyzed.A sediment disturbance experimental platform was built indoors to simulate the sediment coring process.The radial stress field and pore water pressure of the sediment during the coring process were monitored by sensors arranged inside the sediment,and the results of indoor tests verified the correctness of the perturbation theory model.The sampler was carried aboard the deep-sea manned submersible FENDOUZHE and conducted on-site tests at depths of 9298.4 and 9142.8 m in the Kuril-Kamchatka Trench.Pressure-preserved sediment samples were retrieved,with preservation rates of 94.21%and 92.02%,respectively,which are much higher than the current technical indicator of 80%of pressure-holding ratio for deep-sea sediments.The retrieved sediments have obvious stratification characteristics and little disturbance.
基金the National Natural Science Foundation of China(Nos.42206076,42476078)the National Program on Global Change and Air-Sea Interaction(No.GASI-02-SCSCJB01)the China-Malaysia Cooperation Project‘Effect on variability of seasonal monsoon on sedimentary process in Peninsular Malaysia waters’。
文摘The Malacca Strait(MS)is a vital conduit for the exchange of water and sediment between the Indian Ocean and the Pacific Ocean,serving as a critical‘gateway'for sediment transport.Here,we present the geochemical characteristics of surface sediments in the MS to elucidate the relationship between terrestrial material inputs and modern oceanic dynamic transport processes in the strait.The results reveal that the MS can be divided into three distinct geochemical provinces.ProvinceⅠ,located in the central region of the strait,is characterized by residual deposits.The preservation of these residual deposits can be attributed to the restricted sediment supply and the relatively weaker modern sedimentary hydrodynamic conditions.ProvinceⅡ,situated to the north of ProvinceⅠ,exhibits provenance differences between its southern and northern regions.The northern region is primarily supplied by sediments originating from the eastern shelf of the Andaman Sea,whereas sediments derived from Sumatra and the Sunda Shelf are predominantly deposited in the southern part of ProvinceⅡ.ProvinceⅢextends along the western coast of the Malaysian Peninsula,with sediments primarily sourced from the Malaysian Peninsula and the Sunda Shelf,while contributions from Sumatra and the eastern shelf of the Andaman Sea are negligible.River sediments from the Malaysian Peninsula and Sumatra are transported northwestward along their respective coasts by prevailing currents,which also facilitate the transportation of Sunda Shelf sediments within the strait,while sediments from the eastern shelf of the Andaman Sea are delivered to the MS via southward coastal currents during the southwest monsoon period.The southward currents and well-developed eddies potentially impede the northward transport of sediments from the Sunda Shelf and restrict the distribution of Andaman Sea sediments within the strait.This study substantially enhances the understanding of source-to-sink processes in the Indo-Pacific region.
基金supported by the Hunan Provincial Natural Science Foundation of China(Nos.2023JJ40518 and 2023JJ30490)the Scientific Research Foundation of Hunan Provincial Education Department(Nos.21B0511 and 22A0384)the Research Funding Project of Jishou University for talent introduction.
文摘Fluoroquinolones(FQs)have the propensity to accumulate in sediments once introduction into aquatic envi-ronments,thereby posing potential threats to benthic organisms,yet the ecotoxicity of sediment-associated FQs remains unclear.In this study,the toxicokinetics and responses of multiple biomarkers in Bellamya aeruginosa,exposed to the three commonly used FQs(norfloxacin,NOR;ciprofloxacin,CIP;levofloxacin,LEVO)at envi-ronmentally relevant concentrations were investigated under sediment exposure scenario.The results revealed that FQs were effectively ingested by B.aeruginosa from sediments,CIP showing the highest bioaccumulation(180.59μg/kg),followed by NOR(74.49μg/kg)and LEVO(36.02μg/kg).CIP exhibiting a highest uptake rate constant(Ks)(4.64 g/(g·day))and the lowest elimination rate constant(K_(e))(0.05 g/(g·day)).The descending order of biological half-life is as follows:CIP(13.62 days),LEVO(8.14 days),and NOR(6.83 days).NOR induced the activity of superoxide dismutase,catalase,and glutathione-S-transferase while CIP and LEVO depressed their activities and increased malondialdehyde content,indicating a more pronounced oxidative damage to B.aerug-inosa caused by CIP and LEVO than NOR.Furthermore,all three FQs were found to induce DNA damage and elevate acetylcholinesterase activity,suggesting distinct genotoxic and neurotoxic effects.Interestingly,despite its low bioaccumulation potential,LEVO exhibited high toxicity towards B.aeruginosa.These findings enhance our understanding of the ecotoxicity of FQs in sediments,providing further evidence of their potential ecological risks.
基金supported by the Project of Ecological and Environmental Protection Integration Research Institute in Yangtze River Delta(No.ZX2023SZY118)the Special Basic Research Service for the Central Level Public Welfare Research Institute(No.GYZX230409)+1 种基金the National Natural Science Foundation of China(No.42407557)the Belt and Road Special Foundation of the National Key Laboratory of Water Disaster Prevention,China(No.2023491611)。
文摘Organic phosphorus(OP)constitutes an important fraction of total phosphorus in lake sediments,with its mobility being influenced by mineralization and transformation of organic carbon(OC).OP and OC co-exist in various forms in the environment,thus a thorough investigation on the impact of OC fractions on the release of OP in sediments should be comprehensively carried out.This study determined the chemical forms of OP and OC in the sediments over four seasons in Lake Taihu and found temporal and spatial variations in their concentrations.The concentration of total OP and total OC ranged from 133 to 348 mg/kg and 4.77 to 21.19 mg/kg,respectively.Correlation between chemical fractions of OP and OC also revealed that Na OH-extracted OP,and fulvic acid-bound and humic acid-bound OP were positively correlated with humic-OC and hot hydrolysis-OC.These results suggest that the algal-derived OC degradation and mineralization may enhance OP mineralization,converting stable or moderately active OP into active forms or inorganic phosphorus under cyanobacterial bloom.This study provides insight and guiding support for investigating the impact of organic matter components on the transformation of OP after cyanobacterial degradation in eutrophic lakes.
基金supported by the National Natural Science Foundation(Nos.52000024 and 41907335)the Natural Science Foundation of Shanghai(No.23ZR1400700).
文摘The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.
基金Supported by the Southern Marine Science and Engineering Guangdong Laboratory、Zhanjiang(No.ZJW-2019-08)APN、CRRP2019-09MYOnodera、Shinichi Onodera、and the SCS Scholar Grant(No.002029002008/2019)。
文摘Plastic pollution and microplastics in sediments are a growing concern for marine ecosystems worldwide.We examined the vertical distribution and properties of microplastics in beach sediments of Xuwen Coral Reef National Nature Reserve,in Leizhou Peninsula,Zhanjiang,China.Sediment samples were taken in seven locations at 5-cm intervals from the surface to a depth of 30 cm.The vertical distribution of microplastic particles ranged from 0 to 1340 particles per kg on average of 119.05particles per kg.The most prevalent material was fibers(76%),followed by film(12%),fragments(11.2%),and foam(0.8%).The microplastics in size of 1-2 mm constituted the largest percentage(40%)of the total,followed by those in size of<1 mm(26.4%),2-3 mm(21.2%),3-4 mm(9.6%),and 4-5 mm(2.81%).Site S1 observed maximum sizes between 1 and 2 mm,S2 reported higher availability of microplastics with sizes ranging from 0.3 to 1 mm.Six different types of polymers were identified in the investigation,and mostly were polyethylene(PE)and polypropylene(PP).In general,the observation of microplastics in deeper sediments indicates that they have the ability to last for prolonged periods in the marine environment,which may present long-term hazards to benthic creatures.In conclusion,the discovery of microplastics in deep layers of coastal sediments highlights the necessity of minimizing plastic waste and enhancing management strategies to safeguard marine environments.
基金the Natural Science Key Foundation of Fujian ProvinceChina(No.2020J02002)+4 种基金the Hainan Province Science and Technology Special Fund(No.ZDYF2022SHFZ317)the National Natural Science Foundation of China(Nos.U2005207,41976216,41776088,42106224)the Norwegian Institute of FoodFishery and AquacultureGovernance of Marine Plastic Litter in the Arctic。
文摘Microplastic(MP)contamination is becoming a major worldwide concern,affecting terrestrial and aquatic ecosystems.This study investigated the source,distribution,and abundance of MPs in sediments from Dongshan Bay,Fujian,South China,emphasizing particularly the coastline region's susceptibility to tidal impacts in four study sites.The concentrations of MPs in the sediments in the four sites were high from 7.4 to 283.1 items/kg(dry weight).There were notable differences in abundance between the locations and tide levels.Tides influenced the distribution of MPs greatly;however,the estuary areas showed greater MPs abundance during high tide,due possibly to enhanced water turbulence and riverine inputs.Low tide indicated higher concentrations in coastal locations owing to accumulation.Popular varieties,including nylon,polypropylene,and polyethylene,were identified by polymer research,pointing to the origins from fishing,packaging,and mariculture industries.Potential sources were determined using the PCA-K-means statistical analysis,by linking the origins of MPs to domestic activities,fishing,mariculturing,shipping,and packing.Fishing and packing were shown in the Sankey diagram as the two main sources,but their effects varied with research locations and tidal regimes.This study clarified the intricate dynamics of MPs pollution,highlighting the impact of tides on its dispersal and the variety of sources that contribute to this widespread environmental problem in coastal areas.
文摘Industrial activities have contributed so much to the pollution of water bodies and these pollutions have adversely affected the aquatic ecosystem.This study aimed to investigate the ecological risk evaluation of heavy metal accumulation in Aba River bottom sediments:implications for soap and detergent industry wastewater management.Varian AA240 Atomic absorption spectrometer was used to analyse heavy metals.Individual and complex ecological indices were used to evaluate heavy metal contamination in bottom sediments.According to the results,the heavy metal properties of the wastewater indicated that Fe,Pb,Cd,Cr and Cu mean concentration values were higher than the World Health Organization(WHO)and the National Environmental Standards and Regulations Enforcement Agency(NESREA)permissible limits.Heavy metal properties of the surface water in Aba River(dry seasons)showed that Pb,Cd,Cu,Mn,Fe,and Cr,mean concentrations were above the NESREA,WHO and U.S.Environmental Protection Agency(USEPA)permissible limits.Heavy metal properties of the bottom sediments of Aba River(wet and dry season)showed that Pb,Cd,and Fe mean concentrations were significantly higher than the NESREA,WHO and USEPA permissible limits.The heavy metal contamination factor(CF)of sediments obtained from Aba River during the wet and dry season was low and the CFs of each of the assayed heavy metals were less than 1(CD<1).This also signifies the existence of a low contamination in the sediments of the course streams of Aba River during wet and dry season.The pollution load index(PLI)values of Aba River(sediment)indicated that there is no metal pollution at PLI<1 in the sampled sediments.The potential ecological risk index(RI)of Aba River was less than 150(RI<150)indicating a low ecological RI.Abatement of pollutants in the wastewater to permissible concentrations required for natural environment protection is needed.
基金funded by SERB-DST,New Delhi,India for Early Career Research(ECR/2016/001100)during 2017 to 2021.
文摘Elemental concentrations of the siliciclastic sediments from a sedimentary basin provide clues on paleo-weathering,paleoclimate,provenance,and tectonic setting of the basin.Records for Permo-Triassic mass extinction and climatic fluctuations are commonly traced from the sediments in the Gondwana basins.Nevertheless,our understanding on sedimentation,provenance,and regional tectonics of the Raniganj Basin,a Gondwana basin in the eastern India is poor.Minerals including clay particles and major and trace element concentrations of the siliciclastic sediments from different formations of the Raniganj Basin have been studied to establish the paleo-weathering,paleoclimate,provenance,and tectonic settings of the basin.This study suggests that the Talchir Formation experienced cold and dry climatic conditions at the sediment source area,while the Barakar,Raniganj,and Panchet formations had prevailing semiarid climates.The sources of the siliciclastic sediments are from the felsic rocks of the Chotanagpur Granite Gneissic Complex(CGGC).Further,the geochemical results suggest a rift-like(passive)tectonic setting for the Raniganj Basin,while few samples represent the collision tectonic setting of the basement CGGC,formed due to collision of major Indian blocks during the Paleo-Neoproterozoic time.
基金funded by the Basic Research Program of Qinghai Province(2023-ZJ-910M)。
文摘This study investigates the distribution,geochemical behavior,and potential anthropogenic influences of rare earth elements(REEs)in the surface sediments of Qinghai Lake,the largest saline lake in China.A total of 36 surface sediment samples were analyzed for REE concentrations with a combination of self-organizing maps(SOM)and positive matrix factorization(PMF).Results indicate distinct enrichment patterns,with light REEs(LREEs)exhibiting higher concentrations than heavy REEs(HREEs),reflecting natural abundances and geochemical behaviors.The minimum value was found in Lu as low as 0.091 mg/kg,and the maximum concentration was exhibited in Ce at 78.877 mg/kg.Geoaccumulation index(I_(geo))analysis reveals minor to moderate enrichment of specific REEs of Sm and Nd,suggesting possible localized anthropogenic inputs,particularly near river mouths.Spatial analysis using inverse distance weighting(IDW)and self-organizing maps(SOM)highlights significant correlations between REE distributions and riverine inputs,underscoring fluvial transport's role in sedimentary REE dynamics.PMF identifies mixed natural and anthropogenic sources,with agricultural and industrial activities contributing to elevated REE levels in sediment.These findings provide critical insights into the geochemical behavior of REEs in saline lake systems and off er a foundation for pollution control and sustainable resource management in sensitive environments like Qinghai Lake.
基金supported by the National Natural Science Foundation of China(Nos.41888101,41721002)the National Key Research and Development Program of China(No.2022YFF0801101)+2 种基金the Fundamental Research Funds for the Central Universities,the China Postdoctoral Science Foundation(No.2022M713024)the CAS Youth Interdisciplinary Team(No.JCTD-2021-05)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2018498).
文摘The sediments of crater lakes are one of the ideal archives for high-resolution paleoenvironmental reconstruction.This paper presents sedimentary records of 21 crater lakes in monsoonal China and systematically discusses the geographical distribution and formation ages of these crater lakes.Sediment provenance of the crater lakes and its influencing factors were analyzed,and paleoenvironmental sequences and human activities records on different timescales reconstructed by crater lake sediments in monsoonal China were reviewed.The following points are highlighted:(1)Crater lakes in monsoonal China have been shown to preserve continuous long-time sediments that can exceed even 400 ka,although the chronology of some sediments in the southern part is debated and there were currently fewer long time records from the northern part;(2)the sediment provenance of crater lakes in northern China(e.g.,aeolian inputs)was different from that in the south(e.g.,the volcanic-lake rim),due to the different location and deposition conditions of crater lakes;(3)crater lake sediments have been used to reconstruct the history of climate changes on different timescales,but reconstruction studies of glacial-interglacial and decadal-annual scale records and studies of spatial comparisons of records on different timescales still need to be strengthened;(4)the anthropogenic signals,which include cultivation,logging,and industrial activity,are well documented in crater lake sediments from different areas and can therefore provide key evidence for the study of the Anthropocene.
基金Under the auspices of National Natural Science Foundation of China(No.42471179,42071107)。
文摘We measured the content of six heavy-metal elements(Co,Cu,Zn,As,Cd,Pb)in 72 lake surface-sediment samples from the Xizang Autonomous Region(referred to as Xizang)of China,and calculated four indices:enrichment factor(EF),geo-accumulation index(Igeo),pollution load index(PLI),and a comprehensive potential ecological risk index(RI)to explore the differences in the accumulation and the major sources of heavy metals,and to reveal the role of human activities in the ecological environment of high-elevation cold regions.Results show that the heavy-metal contents in lake surface sediment samples in eastern Xizang are much higher than those in central and western areas,and are also higher than the background value of surface soils.Their distribution can be related to regional sources of heavy metals:natural parent material(western Xizang),agriculture(eastern Xizang),mining-related industrial sources(central Xizang),and degree of development of road network(all of Xizang).The majority of lakes in Xizang have a relatively low risk of ecological harm,but there are notable regional peculiarities in the element content and evaluation indices and the lakes in eastern Xizang are at higher risk than those in central and western parts.Lakes at higher ecological risk(such as Lake Butuo(Lake 71)and Samu Co(Lake 68)),remind us that the potential influence of heavy-metal enrichment on lake sediments and aquatic plants should not be overlooked.
基金supported by the Key Project of Natural Science Basic Research Program of Shaanxi Province(2023-JC-ZD-16).
文摘The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study crucial for understanding environmental changes in the region.Despite its importance,research on the Shichuanhe River basin has thus far been primarily focused on riverbank construction,with limited exploration of its sediment characteristics.Although river sediments hold potential for guiding agricultural practices in the area,comprehensive studies on their composition and provenance remain scarce.To address this gap,a systematic sediment sampling campaign was conducted in the lower reaches of the Shichuanhe River,and detailed mineralogical analyses were performed.The results show that the sediment is predominantly composed of detrital quartz and feldspar(albite and orthoclase),with heavy minerals constituting approximately 10%–12%of the total sediment volume.The analysis of the heavy mineral assemblage reveals an absence of signifi cant contributions from igneous rocks in the sedimentary profi le.Furthermore,the distribution patterns of major,trace,and rare-earth elements in the Shichuanhe River’s argillaceous sediments exhibit similarities to those found in the Weihe River’s sediments.Elemental fractionation patterns suggest that the Shichuanhe River sediments are primarily derived from Loess Plateau sediments,aligning with fi ndings from both the Weihe River and the middle reaches of the Yellow River.
基金supported by the National Natural Science Foundation of China(Grant No.51939011)the Science and Technology Program of CNOOC Research Institute(Grant No.2023OTKK03)supported by the program of the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2020326).
文摘Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear strength under varying dissociation conditions have not been thoroughly investigated. To this end,a series of triaxial compression tests were first carried out on sediments with varying initial hydratesaturations along dissociation pathways. Combining measured data with microscale analysis, the underlyingmechanism for the evolution of shear strength in hydrate-bearing sediment was studied undervarying partial dissociation pathways. Moreover, a shear strength model for hydrate-bearing sedimentwas proposed, taking into account the hydrate saturation and the unhydrated water content. Apart fromthe parameters derived from the hydrate characteristic curve, only one additional model parameter isrequired. The proposed model was validated using measured data on hydrate sediments. The resultsindicate that the proposed model can effectively capture the shear strength behavior of hydrate-bearingsediment under varying dissociation paths. Finally, a sensitivity analysis of the model parameters wasconducted to characterize the proposed model.
基金support from the Open Research Fund of the National Center for International Research on Deep Earth Drilling and Resource Development,Ministry of Science and Technology (Grant No.DEDRD-2023-04)the National Natural Science Foundation of China (Grant No.42306237)the Fundamental Research Funds for the Central Universities,China University of Geosciences,Wuhan (Grant No.107-G1323523046).
文摘In the long-term exploitation of natural gas hydrate,the stress change intensifies the creep effect and leads to the destruction of pore structures,which makes it difficult to predict the permeability of hydrate reservoir.Although permeability is crucial to optimize gas recovery for gas hydrate reservoirs,until now,accurately modeling the permeability of hydrate-bearing clayey-silty sediments during the creep process remains a significant challenge.In this study,by combining the nonlinear fractional-order constitutive model and the Kozeny-Carman(KC)equation,a novel creep model for predicting the permeability of hydrate-bearing clayey-silty sediments has been proposed.In addition,experimental tests have been conducted to validate the derived model.The proposed model is further validated against other available test data.When the yield function F<0,the permeability decreases gradually due to the shrinkage of pore space.However,when the yield function F≥0,the penetrating damage bands will be generated.Results show that,once the model parameters are determined appropriately by fitting the test data,the model can also be used to predict permeability under any other stress conditions.This study has a certain guiding significance for elucidating the permeability evolution mechanisms of hydrate-bearing clayey-silty sediments during the extraction of marine gas hydrates.
