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
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
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
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
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
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
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
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
This research conducted a systematic study on the processes of migration of energy-related pollutants caused by nanoparticles in marine sediments,as well as their impacts on the durability of offshore infrastructure.W...This research conducted a systematic study on the processes of migration of energy-related pollutants caused by nanoparticles in marine sediments,as well as their impacts on the durability of offshore infrastructure.While focused on representative nanoparticles(nano-TiO_(2),nano-Fe_(3)O_(4),and carbon nanotubes)and select energy pollutants,experimental data showed these materials greatly enhanced the movement of pollutants,increasing migration distances from 1.6 to 2.9 times.The carbon nanotubes possessed the greatest carrying effect,increasing the phenanthrene migration distance by 286 percent.The study determined surface properties of nanoparticles,pH of the liquid environment,ionic concentration,and organic matter level as major elements impacting pollutant mobility.Laboratory simulations,while controlled and reproducible,necessarily simplified the complex dynamics of real marine environments.Nanoparticle-sorbate systems were found to be effective in enhancing the deterioration rate of materials used in offshore constructions,with CNTPAHs composites causing carbon steel to corrode by 183% more than if PAHs were used without the composites.This change in corrosion behaviour was shown in other tests to be caused by a change in dynamics of the corrosion products'structural constituents and the various electrochemical properties present on the surface of the material.Samples of concrete showed a spend of 90 days in the composite system resulted in a 26.8% decrease in compressive strength compared to control conditions which had only a 15.3%.Therefore,taking into account the results,strategies were formulated to ensure durability for offshore infrastructure including surface modified anticorrosion coatings,surveillance and alert systems,and integrated protective systems.Future field validation studies are needed to verify these laboratory findings under actual marine conditions.This study helps to comprehend the behaviour of nanoparticles in intricate marine ecosystems,providing support for the sustainable advancement of offshore infrastructure and the protection of the marine environment.展开更多
The study aims to investigate uranium species in the sediments of the natural-technogenic system within a sludge storage facility in Russia.The relevance of this work is underscored by the need to assess the geochemic...The study aims to investigate uranium species in the sediments of the natural-technogenic system within a sludge storage facility in Russia.The relevance of this work is underscored by the need to assess the geochemical mobility of radionuclides,a critical factor for predicting their migration and environmental impact.The objective of the research was to determine the uranium species in both peat and sedimentary rock samples of the sludge storage facility and the adjacent area.Laboratory analyses included XRD,XRF analysis using synchrotron radiation,and scanning electron microscopy to study the composition and properties of minerals.The uranium species were further identified using a modified Tessier sequential extraction method.The results revealed that uranium predominantly occurs in a stable silicate-bound form(up to 80%)in sedimentary rocks,indicating minimal geochemical mobility.In contrast,in peat deposits,uranium is primarily associated with manganese and iron oxides(30–60%)as well as organic matter(5–40%),with the most mobile forms constituting less than 5%.The decrease in uranium concentration with distance from the facility was attributed to sorption onto organic matter and co-precipitation with mineral compounds,manganese and iron oxides,which serve as effective natural sorbents.The findings highlight the critical role of organic matter and metal oxides in limiting uranium migration,thus identifying them as key components in the formation of natural barriers for radionuclides.These results are crucial for assessing environmental risks associated with radioactive waste management and for developing strategies to minimize the ecological impact of sludge storages.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
Total organic carbon in lake surface sediments(STOC)constitutes a pivotal biogeochemical component within the critical interface of the global carbon cycle,where recently deposited organic matter undergoes burial or m...Total organic carbon in lake surface sediments(STOC)constitutes a pivotal biogeochemical component within the critical interface of the global carbon cycle,where recently deposited organic matter undergoes burial or mineralization,thereby playing a key role in carbon turnover and storage in inland water ecosystems.However,previous studies,constrained by local-scale observations and linear analytical methods,have not systematically characterized the global spatial patterns of STOC values and the mechanisms driving their variability.Here,by integrating STOC measurements from 89 lakes across the Tibetan Plateau with STOC data of 1070 lakes compiled based on a literature search,we present the first machine-learning-based assessment of global lake STOC patterns.Our results indicate that lake STOC concentrations peaked between 45°N and 70°N in the Northern Hemisphere,particularly in northern North America,whereas very high latitudes(>70°N)and mid-to low-latitude regions exhibited comparatively lower values.Structural equation modeling revealed that among basin characteristics,soil organic carbon and ice/snow cover were the strongest direct controls on lake STOC distribution,while temperature indirectly influenced STOC by modulating both variables.Although human activities affect STOC globally,their overall influence was modest.We conclude that temperature primarily governs the global spatial distribution of lake STOC concentrations through its influence on catchment processes.展开更多
The flow behaviors of gas and water in hydrate-bearing sediments(HBS)are significantly affected by the threshold pressure gradient(TPG).During long-term natural gas hydrates(NGHs)mining,there exists creep deformation ...The flow behaviors of gas and water in hydrate-bearing sediments(HBS)are significantly affected by the threshold pressure gradient(TPG).During long-term natural gas hydrates(NGHs)mining,there exists creep deformation in HBS,which significantly alters pore structures,makes the flow path of fluid more complex,and leads to changes in TPG.Thus,clarifying the evolution of TPG in HBS during creep is essential for NGH production,but it also confronts enormous challenges.In this study,based on the nonlinear creep constitutive model,a novel theoretical TPG model of HBS during creep is proposed that considers pore structures and hydrate pore morphology.The established model is validated against experimental data,demonstrating its ability to capture the evolution of TPG and permeability in HBS during creep.Additionally,the relationship between initial hydrate saturation and TPG of HBS during creep is revealed by sensitivity analysis.The creep strain increases with the decrease in initial hydrate saturation,leading to a greater TPG and a lower permeability.The evolution of TPG at the stable creep stage and the accelerated creep stage is primarily controlled by the Kelvin element and visco-plastic element,respectively.This novel proposed model provides a mechanistic understanding of TPG evolution in HBS during creep,and it is of great significance to optimize the exploitation of NGHs.展开更多
The flux of dissolved inorganic nitrogen(DIN),predominantly nitrate(NO_(3)^(-))and ammonium(NH_(4)^(+)),from land to coastal waters via rivers is commonly estimated simply by multiplying water flux with nitrogen conce...The flux of dissolved inorganic nitrogen(DIN),predominantly nitrate(NO_(3)^(-))and ammonium(NH_(4)^(+)),from land to coastal waters via rivers is commonly estimated simply by multiplying water flux with nitrogen concentration.Understanding DIN fluxes in gated estuaries is critical as these systems often serve as hotspots for nutrient transformations,influencing coastal water quality and ecosystem health.However,the subsequent interactions involving NO_(3)^(-)and NH_(4)^(+)adsorption or desorption on suspended sediments are often overlooked.To better understand the impact of these interactions on the overall NO_(3)^(-)and NH_(4)^(+)sorption or desorption and subsequently,the mobility and transport to the coastal zone,we conducted a series of NO_(3)^(-)and NH_(4)^(+)adsorption and desorption experiments.These experiments involved varying suspended sediment concentrations,particle sizes,salinities,and sea-salt ions to assess their potential effects.Results indicate that desorption of NO_(3)^(-)and NH_(4)^(+)from suspended sediments is more prominent than adsorption,with NH_(4)^(+)desorption being particularly significant.Notably,at low suspended particle concentrations and high salinity,NH_(4)^(+)desorption from sediments increased markedly,which further amplified in polyhaline conditions.This effect could result from ion pairing between NH_(4)^(+)and seawater anions,along with competition from seawater cations for sediment cation exchange sites,enhancing NH_(4)^(+)diffusion from estuarine sediments,and the elevated NH_(4)^(+)release could promote DIN transport to nearshore waters,especially in gated estuaries where sediment resuspension occurs.Given the critical role of NH_(4)^(+)in estuarine nitrogen cycling,ignoring these dynamics could lead to underestimations of DIN transport in river-estuary systems.Therefore,incorporating sediment dynamics into DIN flux estimations is crucial for accurately assessing nitrogen transport in gated estuaries.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
The concentrations of polycyclic aromatic hydrocarbons(PAHs),their sources and toxic equivalent(TEQ)in soil,suspended matter and bottom sediments in the Fatala River Basin ecosystem were obtained for the fi rst time t...The concentrations of polycyclic aromatic hydrocarbons(PAHs),their sources and toxic equivalent(TEQ)in soil,suspended matter and bottom sediments in the Fatala River Basin ecosystem were obtained for the fi rst time to our knowledge.Determination of 14 PAHs(ΣPAHs)was carried out using high-performance liquid chromatography.TheΣPAH content in soil ranged from 13 to 50,920(Me=820)ng/g.The composition of PAHs(high proportion of low-molecular-weight compounds and values of individual PAHs ratios)refl ected the signifi cant oil pollution of soil.Contaminated soil was localated in the central part of the Fatala River Basin.The median benzo(a)pyrene toxic equivalent of soil at the study site was 1.08(range,0.05 to 53.16)ngTEQ/g,showing generally low soil toxicity.TheΣPAH content in suspended matter was in the range of 33 to 1316(Me=309)ng/L.TheΣPAH content in bottom sediments ranged from 36 to 6943(Me=478)ng/L,corresponding to clean and moderately contaminated sediments.TheΣPAH content in bottom sediments depended on the anthropogenic impact on the Fatala River Basin territory and the bottom sediment features.Bottom sediments and suspended matter had a low toxic equivalent.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
Environmental problems from heavy metals(HMs)attract global attention.Accurately identifying sources and quantitatively evaluating ecological risks are keys for HMs pollution prevention.Dongting Lake in China was inve...Environmental problems from heavy metals(HMs)attract global attention.Accurately identifying sources and quantitatively evaluating ecological risks are keys for HMs pollution prevention.Dongting Lake in China was investigated through integrated methods like positive matrix factorization and Nemerow integrated risk index to examine spatial distribution,contamination characteristics,pollution sources,and the contribution of each source and pollutant to the ecological risk of 14 HMs in its surface sediments.Results showed that the mean concentrations of HMs were 0.82-9.44 times greater than the corresponding background values.The spatial distribution of HMs varied significantly,with high values of As,Cd,Mn,Pb,Sn,Tl and Zn concentrated in the sediments from Xiangjiang inlet and Yangtze outlet;Co,Cr,Cu,Ni and V in the Lishui sediments;Hg and Sb in the sediments from Yuanjiang and Zishui inlets,respectively.The accumulation of HMs was affected by five sources:mercury mining and atmospheric deposition(F1)(17.99%),urban domestic sewage and industrial sewage discharge(F2)(24.44%),antimony ore mining and smelting(F3)(6.50%),non-ferrous metal mining and extended processing industrial sources(F4)(15.72%),and mixed sources mainly from natural sources and agricultural sources(F5)(35.35%).F1 and F2 were identified as priority pollution sources;Cd,Hg,Tl,Sb and As,especially Cd and Hg,posed relatively high ecological risks and were prioritized HMs for control.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
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.
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 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(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.
文摘This research conducted a systematic study on the processes of migration of energy-related pollutants caused by nanoparticles in marine sediments,as well as their impacts on the durability of offshore infrastructure.While focused on representative nanoparticles(nano-TiO_(2),nano-Fe_(3)O_(4),and carbon nanotubes)and select energy pollutants,experimental data showed these materials greatly enhanced the movement of pollutants,increasing migration distances from 1.6 to 2.9 times.The carbon nanotubes possessed the greatest carrying effect,increasing the phenanthrene migration distance by 286 percent.The study determined surface properties of nanoparticles,pH of the liquid environment,ionic concentration,and organic matter level as major elements impacting pollutant mobility.Laboratory simulations,while controlled and reproducible,necessarily simplified the complex dynamics of real marine environments.Nanoparticle-sorbate systems were found to be effective in enhancing the deterioration rate of materials used in offshore constructions,with CNTPAHs composites causing carbon steel to corrode by 183% more than if PAHs were used without the composites.This change in corrosion behaviour was shown in other tests to be caused by a change in dynamics of the corrosion products'structural constituents and the various electrochemical properties present on the surface of the material.Samples of concrete showed a spend of 90 days in the composite system resulted in a 26.8% decrease in compressive strength compared to control conditions which had only a 15.3%.Therefore,taking into account the results,strategies were formulated to ensure durability for offshore infrastructure including surface modified anticorrosion coatings,surveillance and alert systems,and integrated protective systems.Future field validation studies are needed to verify these laboratory findings under actual marine conditions.This study helps to comprehend the behaviour of nanoparticles in intricate marine ecosystems,providing support for the sustainable advancement of offshore infrastructure and the protection of the marine environment.
基金supported by the Russian Science Foundation grant number 23-27-00362,https://rscf.ru/en/project/23-27-00362/.
文摘The study aims to investigate uranium species in the sediments of the natural-technogenic system within a sludge storage facility in Russia.The relevance of this work is underscored by the need to assess the geochemical mobility of radionuclides,a critical factor for predicting their migration and environmental impact.The objective of the research was to determine the uranium species in both peat and sedimentary rock samples of the sludge storage facility and the adjacent area.Laboratory analyses included XRD,XRF analysis using synchrotron radiation,and scanning electron microscopy to study the composition and properties of minerals.The uranium species were further identified using a modified Tessier sequential extraction method.The results revealed that uranium predominantly occurs in a stable silicate-bound form(up to 80%)in sedimentary rocks,indicating minimal geochemical mobility.In contrast,in peat deposits,uranium is primarily associated with manganese and iron oxides(30–60%)as well as organic matter(5–40%),with the most mobile forms constituting less than 5%.The decrease in uranium concentration with distance from the facility was attributed to sorption onto organic matter and co-precipitation with mineral compounds,manganese and iron oxides,which serve as effective natural sorbents.The findings highlight the critical role of organic matter and metal oxides in limiting uranium migration,thus identifying them as key components in the formation of natural barriers for radionuclides.These results are crucial for assessing environmental risks associated with radioactive waste management and for developing strategies to minimize the ecological impact of sludge storages.
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National Natural Science Foundation of China,No.42225105,No.42494821,No.42201175The China Postdoctoral Science Foundation,No.2023M733605。
文摘Total organic carbon in lake surface sediments(STOC)constitutes a pivotal biogeochemical component within the critical interface of the global carbon cycle,where recently deposited organic matter undergoes burial or mineralization,thereby playing a key role in carbon turnover and storage in inland water ecosystems.However,previous studies,constrained by local-scale observations and linear analytical methods,have not systematically characterized the global spatial patterns of STOC values and the mechanisms driving their variability.Here,by integrating STOC measurements from 89 lakes across the Tibetan Plateau with STOC data of 1070 lakes compiled based on a literature search,we present the first machine-learning-based assessment of global lake STOC patterns.Our results indicate that lake STOC concentrations peaked between 45°N and 70°N in the Northern Hemisphere,particularly in northern North America,whereas very high latitudes(>70°N)and mid-to low-latitude regions exhibited comparatively lower values.Structural equation modeling revealed that among basin characteristics,soil organic carbon and ice/snow cover were the strongest direct controls on lake STOC distribution,while temperature indirectly influenced STOC by modulating both variables.Although human activities affect STOC globally,their overall influence was modest.We conclude that temperature primarily governs the global spatial distribution of lake STOC concentrations through its influence on catchment processes.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515110376)the Open Research Fund of National Center for International Research on Deep Earth Drilling and Resource Development,Ministry of Science and Technology(Grant No.DEDRD-2023-04)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Grant No.107-G1323523046).
文摘The flow behaviors of gas and water in hydrate-bearing sediments(HBS)are significantly affected by the threshold pressure gradient(TPG).During long-term natural gas hydrates(NGHs)mining,there exists creep deformation in HBS,which significantly alters pore structures,makes the flow path of fluid more complex,and leads to changes in TPG.Thus,clarifying the evolution of TPG in HBS during creep is essential for NGH production,but it also confronts enormous challenges.In this study,based on the nonlinear creep constitutive model,a novel theoretical TPG model of HBS during creep is proposed that considers pore structures and hydrate pore morphology.The established model is validated against experimental data,demonstrating its ability to capture the evolution of TPG and permeability in HBS during creep.Additionally,the relationship between initial hydrate saturation and TPG of HBS during creep is revealed by sensitivity analysis.The creep strain increases with the decrease in initial hydrate saturation,leading to a greater TPG and a lower permeability.The evolution of TPG at the stable creep stage and the accelerated creep stage is primarily controlled by the Kelvin element and visco-plastic element,respectively.This novel proposed model provides a mechanistic understanding of TPG evolution in HBS during creep,and it is of great significance to optimize the exploitation of NGHs.
基金Supported by the Tianjin Key R&D Program(No.21YFSNSN00220)。
文摘The flux of dissolved inorganic nitrogen(DIN),predominantly nitrate(NO_(3)^(-))and ammonium(NH_(4)^(+)),from land to coastal waters via rivers is commonly estimated simply by multiplying water flux with nitrogen concentration.Understanding DIN fluxes in gated estuaries is critical as these systems often serve as hotspots for nutrient transformations,influencing coastal water quality and ecosystem health.However,the subsequent interactions involving NO_(3)^(-)and NH_(4)^(+)adsorption or desorption on suspended sediments are often overlooked.To better understand the impact of these interactions on the overall NO_(3)^(-)and NH_(4)^(+)sorption or desorption and subsequently,the mobility and transport to the coastal zone,we conducted a series of NO_(3)^(-)and NH_(4)^(+)adsorption and desorption experiments.These experiments involved varying suspended sediment concentrations,particle sizes,salinities,and sea-salt ions to assess their potential effects.Results indicate that desorption of NO_(3)^(-)and NH_(4)^(+)from suspended sediments is more prominent than adsorption,with NH_(4)^(+)desorption being particularly significant.Notably,at low suspended particle concentrations and high salinity,NH_(4)^(+)desorption from sediments increased markedly,which further amplified in polyhaline conditions.This effect could result from ion pairing between NH_(4)^(+)and seawater anions,along with competition from seawater cations for sediment cation exchange sites,enhancing NH_(4)^(+)diffusion from estuarine sediments,and the elevated NH_(4)^(+)release could promote DIN transport to nearshore waters,especially in gated estuaries where sediment resuspension occurs.Given the critical role of NH_(4)^(+)in estuarine nitrogen cycling,ignoring these dynamics could lead to underestimations of DIN transport in river-estuary systems.Therefore,incorporating sediment dynamics into DIN flux estimations is crucial for accurately assessing nitrogen transport in gated estuaries.
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support of the Project of the Russian Federation represented by the Ministry of Science and Higher Education of the Russian Federation:assistance in the form of grants in accordance with paragraph 4 of article 78.1 of the Budget Code of the Russian Federation(agreement No.075-15-2023-592 on subject No.13.2251.21.0216)CEREMAC-G own research fund and a Support special fi nancier of the Ministry of Higher Education,Scientifi c Research and Innovation(MESRSI)of the Republic of Guinea.
文摘The concentrations of polycyclic aromatic hydrocarbons(PAHs),their sources and toxic equivalent(TEQ)in soil,suspended matter and bottom sediments in the Fatala River Basin ecosystem were obtained for the fi rst time to our knowledge.Determination of 14 PAHs(ΣPAHs)was carried out using high-performance liquid chromatography.TheΣPAH content in soil ranged from 13 to 50,920(Me=820)ng/g.The composition of PAHs(high proportion of low-molecular-weight compounds and values of individual PAHs ratios)refl ected the signifi cant oil pollution of soil.Contaminated soil was localated in the central part of the Fatala River Basin.The median benzo(a)pyrene toxic equivalent of soil at the study site was 1.08(range,0.05 to 53.16)ngTEQ/g,showing generally low soil toxicity.TheΣPAH content in suspended matter was in the range of 33 to 1316(Me=309)ng/L.TheΣPAH content in bottom sediments ranged from 36 to 6943(Me=478)ng/L,corresponding to clean and moderately contaminated sediments.TheΣPAH content in bottom sediments depended on the anthropogenic impact on the Fatala River Basin territory and the bottom sediment features.Bottom sediments and suspended matter had a low toxic equivalent.
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financially supported by the Key Research and Development Program of Hunan Province,China(No.2023SK2006)the Natural Science Foundation of Hunan Province,China(No.2023JJ50057)+2 种基金the Science and Technology Plan Project of Geological Bureau of Hunan Province,China(No.HNGSTP202411)the Open Project of Key Laboratory of the Ministry of Natural Resources,China(No.BL202105)the Natural Science Foundation of Changsha City,China(No.kq2202090)。
文摘Environmental problems from heavy metals(HMs)attract global attention.Accurately identifying sources and quantitatively evaluating ecological risks are keys for HMs pollution prevention.Dongting Lake in China was investigated through integrated methods like positive matrix factorization and Nemerow integrated risk index to examine spatial distribution,contamination characteristics,pollution sources,and the contribution of each source and pollutant to the ecological risk of 14 HMs in its surface sediments.Results showed that the mean concentrations of HMs were 0.82-9.44 times greater than the corresponding background values.The spatial distribution of HMs varied significantly,with high values of As,Cd,Mn,Pb,Sn,Tl and Zn concentrated in the sediments from Xiangjiang inlet and Yangtze outlet;Co,Cr,Cu,Ni and V in the Lishui sediments;Hg and Sb in the sediments from Yuanjiang and Zishui inlets,respectively.The accumulation of HMs was affected by five sources:mercury mining and atmospheric deposition(F1)(17.99%),urban domestic sewage and industrial sewage discharge(F2)(24.44%),antimony ore mining and smelting(F3)(6.50%),non-ferrous metal mining and extended processing industrial sources(F4)(15.72%),and mixed sources mainly from natural sources and agricultural sources(F5)(35.35%).F1 and F2 were identified as priority pollution sources;Cd,Hg,Tl,Sb and As,especially Cd and Hg,posed relatively high ecological risks and were prioritized HMs for control.
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.
