On the basis of three geological models and several orebody boundaries, a method of grid subdivision and integral has been proposed to calculate and evaluate the resources of cobalt-rich crusts on the seamounts in the...On the basis of three geological models and several orebody boundaries, a method of grid subdivision and integral has been proposed to calculate and evaluate the resources of cobalt-rich crusts on the seamounts in the central Pacific Ocean. The formulas of this method are deduced and the interface of program module is designed. The method is carried out in the software "Auto mapping system of submarine topography and geomorphology MBChart". This method and program will possibly become a potential tool to calculate the resources of seamounts and determine the target diggings for China' s next Five-year Plan.展开更多
Rare earth elements(REEs) and major elements of 25 cobalt-rich crusts obtained from different depths of Mid-Pacific M seamount were analyzed using inductively coupled plasma-atomic emission spectrometer and gravimet...Rare earth elements(REEs) and major elements of 25 cobalt-rich crusts obtained from different depths of Mid-Pacific M seamount were analyzed using inductively coupled plasma-atomic emission spectrometer and gravimetric method.The results showed that they were hydrogenous crusts with average ∑REE content of 2084.69 μg/g and the light REE(LREE)/heavy REE(HREE) ratio of 4.84.The shale-normalized REE patterns showed positive Ce anomalies.The total content of strictly trivalent REEs increased with water depth.The Ce content and LREE/HREE ratios in Fe-Mn crusts above 2000 m were lower than those below 2000 m.The change in REE with water depth could be explained by two processes:adsorptive scavenging by setting matters and behaviors of REE in seawater.However, the Ce abundance took no obvious correlation with water depth reflects the constant Ce flux.The Ce in crusts existed mainly as Ce(IV), implying that the oxidative-enriching process was controlled by kinetic factors.展开更多
A biostratigraphic study on calcareous nannofossils from the CM3D06 Co-rich ferromanganese crust from the Magellan seamounts in the northwestern Pacific enabled estimation of depositional age. The bio-imprinting of ca...A biostratigraphic study on calcareous nannofossils from the CM3D06 Co-rich ferromanganese crust from the Magellan seamounts in the northwestern Pacific enabled estimation of depositional age. The bio-imprinting of calcareous nannofossils and other fossil species suggests six age ranges for the nannofossils: late Cretaceous, late Paleocene, (early, middle, late) Eocene, middle Miocene, late Pliocene, and Pleistocene. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were used to test the Co-rich crusts, and a variety of molecular fossils were detected, such as chloroform bituminous "A" , n-alkane, isoprenoid and sterol. Peak carbon and molecular indices (such as C23-/C24+, CPI, Pr/Ph, Pr/nC17, Ph/nCxs and j13C) indicate that the parent organic matter is dominated by marine phytoplankton and thallogen whereas there is little input of terrestrial organic matter. Researches on calcareous nannofossils, molecular fossils and molecular organic geochemistry data reveal that the Paleocene/Eocene (P/E) global event is recorded in the cobalt- rich crusts from the northwestern Pacific Ocean. A succession of biomes can be observed near the 85 mm boundary (about 55 Ma), i.e., the disappearance of the late Cretaceous Watznaueria barnesae and Zigodicus spiralis, and Broisonia parka microbiotas above the P/E boundary, and the bloom of Coccolithus formosus, Discoaster multiradiatus, Discoaster mohleri and Discoaster sp. below the boundary. Typical parameters of molecular fossils, such as saturated hydrocarbon components and carbon-number maxima, Pr/Ph, Pr/C17, Ph/C18, distribution types of sterols, Ts/Tm ratios and bacterial hopane, also exhibit dramatic changes near the P/E boundary. These integrated results illustrate that the biome succession of calcareous nannofossils, relative content of molecular fossils and molecular indices in the cobalt-rich crusts near the 85 mm boundary faithfully record the P/E global event.展开更多
Organic matter in cobalt-rich crust (CRC) from the Marcus-Wake Seamounts of the western Pacific Ocean, Sample CM1D03, has been analyzed to understand the source, geochemistry and mineralization of organic matter, an...Organic matter in cobalt-rich crust (CRC) from the Marcus-Wake Seamounts of the western Pacific Ocean, Sample CM1D03, has been analyzed to understand the source, geochemistry and mineralization of organic matter, and the mineralization environment. Biomarkers, includingn-alkanes, isoprenoids, terpanes and sterols, have been detected in various layers of the CRC sample, using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The content of organic carbon (OC) and its stable isotope (δ13C), and the combined features of the biomarkers show that the mineralized organic matter in CM1D03 CRC was mainly derived from microorganisms and lower plankton (e.g., bacteria and algae, respectively) from marine surface water, with some terrestrial higher plant components. The ratio of chloroform bitu-men "A": OC was high in the CRC, between 10.51 and 20.66, showing significant migration characteristics of n-alkanes. Four mineralization categories of organic matter were recognized based on GC chromatograms ofn-alkane molecules: (1) primitive type (bacteria and algae), which is characterized by moderately mature ofn-alkanes preserving the original characteristics of the organic matter from microorganisms and lower plankton; (2) microbial degradation type, which is characterized by low contents ofn-alkanes and rising baseline in the chromatogram, with the "bulge" being the products of organic matter by biodegradation; (3) organic matter migration type, which is characterized by low carbon number ofn-alkanes withnC18 as the main peak carbon, without odd even predominance, and low concentrations of isoprenoids and hydro-carbons with high carbon number; and (4) organic matter hydrothermal type, which is characterized by relatively low concentration of small molecular weightn-alkanes, pristane, and phytane, accompanied by higher concentration ofn-alkanes with carbon number greater thannC18. This study shows that biomarkers can record controlling factors of mineralization and their variation.展开更多
The Qinghai-Tibet Plateau is now experiencing ecological degradation risks as a result of climate change and human activities.The alpine grassland ecology in permafrost zones is fragile and susceptible to deterioratio...The Qinghai-Tibet Plateau is now experiencing ecological degradation risks as a result of climate change and human activities.The alpine grassland ecology in permafrost zones is fragile and susceptible to deterioration due to its high altitude,low temperature,and limited oxygen,which complicates the repair of damaged land.Biological soil crusts(BSCs)are crucial for land restoration in plateau regions because they can thrive in harsh conditions and have environmentally beneficial traits.Inoculated biological soil crust(IBSC)has shown success in low-altitude desert regions,but may not be easily duplicated to the plateau environment.Therefore,it is essential to do a comprehensive and multifaceted analysis of the basic theoretical comprehension and practical application of BSCs on the Tibetan Plateau.This review article aims to provide a brief summary of the ecological significance and the mechanisms related to the creation,growth,and progression of BSCs.It discusses the techniques used for cultivating BSCs in laboratories and using them in the field,focusing on the Qinghai-Tibet Plateau circumstance.We thoroughly discussed the potential and the required paths for further studies.This study may be used as a basis for selecting suitable microbial strains and accompanying supplemental actions for implementing IBSCs in the Qinghai-Tibet Plateau.展开更多
Globally,many lakes are drying up,leaving exposed lakebeds where wind erosion releases dust and sand rich in salt and harmful heavy metals into the atmosphere.Therefore,understanding the characteristics and spatial di...Globally,many lakes are drying up,leaving exposed lakebeds where wind erosion releases dust and sand rich in salt and harmful heavy metals into the atmosphere.Therefore,understanding the characteristics and spatial distribution of playa surface crusts is important to recognize the manifestation of salt dust storms.The objective of this study was to explore the playa surface crust types as well as their spatial distribution and evolution of Qehan Lake in Inner Mongolia Autonomous Region,China to understand the salt dust release potential of different types of playa surface crusts.Various crust characteristics were investigated by field sampling in Qehan Lake,and playa surface crusts were further divided into five types:vegetated areas,salt crusts,clay flats,curly crusts,and margins.It should be noted that curly crusts were distributed in clay flats and covered only a small area in Qehan Lake.The spatial distribution characteristics of playa surface crust types were obtained by supervised classification of remote sensing images,and the salt dust release potential of crusts was explored by the wind tunnel experiments.The field investigation of Qehan Lake revealed that playa surface crust types had a circum-lake band distribution from the inside to the outside of this lake,which were successively vegetated areas,clay flats,salt crusts,and margins.The spatial distribution patterns of playa surface crust types were mainly controlled by the hydrodynamics of the playa,soil texture,and groundwater.There was a significant negative correlation between crust thickness and electrical conductivity.The results of the wind tunnel experiments showed that the initial threshold of friction wind velocity for the salt dust release was higher in clay flats(0.7–0.8 m/s)than in salt crusts(0.5–0.6 m/s).Moreover,the particle leap impact processes occurring under natural conditions may reduce this threshold value.Salinity was the main factor controlling the difference in the initial threshold of friction wind velocity for the salt dust release of clay flats and salt crusts.This study provides a scientific reference for understanding how salt dust is released from a lakebed,which may be used for ecological restoration of dry salt lakes.展开更多
In 2001, the International Seabed Authority (ISBA) initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crust...In 2001, the International Seabed Authority (ISBA) initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crusts in the Area at its 7th session. Since then, the consideration of the Regulations has been mainly focused on the size of areas to be allocated for exploration and exploitation of the crusts. This paper, based on the investigation data and the analysis of the distribution characteristics of the crusts, suggests a model for determining the size of areas for exploration and exploitation of the crusts, taking into account various factors such as production scale, crust thickness and grade, mineable area proportion, recovery efficiency, exploration venture, and so on. Through the modeling, the paper suggests that the exploration area (the area covered by each application for approval of a plan of work for exploration of cobalt-rich crusts) shall be 4 856 km2 and the exploitation area (the mine site area) shall be 1 214 km2, for 20 years of 1 million wet tonnes annual production.展开更多
Noble gas isotopic compositions of various layers in three-layered (outer, porous and compact layers) cobalt-rich ferromanganese crusts and their basaltic and phosphorite substrates from the western Pacific Ocean we...Noble gas isotopic compositions of various layers in three-layered (outer, porous and compact layers) cobalt-rich ferromanganese crusts and their basaltic and phosphorite substrates from the western Pacific Ocean were analyzed by using a high vacuum gas mass spectrum. The analytical results show that the noble gases in the Co-rich crusts have derived mainly from the ambient seawater, extraterrestrial grains such as interplanetary dust particles (IDPs) and wind-borne continental dust grains, and locally formation water in the submarine sediments, but different noble gases have different sources. He in the crusts derives predominantly from the extraterrestrial grains, with a negligible amount of radiogenic He from the eolian dust grains. Ar is sourced mainly from the dissolved air in the seawater and insignificantly from radiogenic Ar in the eolian continental dust grains or the formation water. Xe and Ne derive mainly from the seawater, with minor amounts of extraterrestrial Xe and Ne in the IDPs. Compared with the porous and outer layers, the compact layer has a relatively high 4He content and lower 3He/4He ratios, suggesting that marine phosphatization might have greatly modified the noble gas isotopic compositions of the crusts. Besides, the 3He/4He values of the basaltic substrates of the cobalt-rich crusts are very low and their R/R. ratios are mostly 〈0.1 R., which are similar to that of phosphorite substrates (0.087 R.), but much lower than that of fresh submarine MORB (8.75±14 Ra) or seamount basalts (3-43 Ra), implying that the basaltic substrates have suffered strong water/rock interaction and reacted with radiogenic ^4He and P-rich upwelling marine currents during phosphatization. The trace elements released in the basalt/seawater interaction might favor the growth of cobalt-rich crusts. The relatively low ^3He/^4He values in the seamount basalts may be used as an important exploration criterion for the cobalt-rich ferromanganese crusts.展开更多
An ammonia leaching process was utilized to extract Co, Ni and Cu from oceanic polymetallic nodules, whereas an acid leaching process was utilized to extract Co, Ni, Cu, Zn and Mn from cobalt-rich crusts. Both process...An ammonia leaching process was utilized to extract Co, Ni and Cu from oceanic polymetallic nodules, whereas an acid leaching process was utilized to extract Co, Ni, Cu, Zn and Mn from cobalt-rich crusts. Both processes produced nanometer materials-ammonia leaching residue and acid leaching residue. A systematic study was conducted on the phase, composition and physicochemistry properties of these residues. The result shows that both residues contain a large amount of nanometer minerals. Ammonia leaching residue mainly consists of rhodochrosite, with the average grain diameter of 17.9 nm; whereas the acid leaching residue mainly consists of well-developed bassanite, with the average grain deameter of 9.5 nm. The bassanite also has a microporous structure, the volume of the pore space is 1.23×10-2 mL/g. Both the ammonia and acid leaching residues have a large specific surface area, and they display a strong adsorption capacity to saturate sodium chloride vapour, N2 and SO2. Both residues have high展开更多
A detailed study on a small scale of the effect of phosphatization on the chemistry of marine cobalt-rich ferromanganese crusts supplies useful information for the evaluation and comprehensive utilization of crust min...A detailed study on a small scale of the effect of phosphatization on the chemistry of marine cobalt-rich ferromanganese crusts supplies useful information for the evaluation and comprehensive utilization of crust mineral resources. Sub-samples from top to bottom of a 10-cm thick sample from the NW Pacific Magellan seamount were taken at 5 mm intervals. The concentration profiles of ore-forming and rare earth elements show that obvious differences exist between young unphosphatized crusts and old phosphatized crusts. In the old crusts Fe, Mn, Si, Al, Zn, Mg, Co, Ni and Cu elements are depleted and Ca, P, Sr, Ba and Pb elements are enriched. The order of depletion is Co > Ni > Mg > Al > Mn > Si> Cu > Zn > Fe, while the order of enrichment is P > Ca > Ba > Pb > Sr. The phosphate mineral controls the concentration variation of the ore-forming elements in crusts and causes loss of the main ore-forming elements such as Co and Ni. The phosphatization also affects the abundance of REEs in the crusts. REEs are more abundant and the content of Ce in old crusts is higher than that in young crusts, however, the pattern of REEs and their fractionation characteristics in new and old crusts are not fundamentally changed. A Y-positive anomaly in old crusts has no relationship to the phosphatization.展开更多
Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two ...Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous(more than 70.0 Ma). There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossils preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene(E/O) transition. The results show the transitions and recombination of species in the biotic community during the E/O transition obviously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change.展开更多
Biological soil crusts (BSCs) play an important role in surface soil hydrology. Soils dominated with moss BSCs may have higher infiltration rates than those dominated with cyanobacteria or algal BSCs. However, it is...Biological soil crusts (BSCs) play an important role in surface soil hydrology. Soils dominated with moss BSCs may have higher infiltration rates than those dominated with cyanobacteria or algal BSCs. However, it is unnown whether improved infiltration in moss BSCs is accompanied by an increase in soil hydraulic conductivity or water retention capacity. We investigated this question in the Tengger Desert, where a 43-year-old revegetation program has promoted the formation of two distinct types of BSCs along topographic positions, i.e. the moss-dominated BSCs on the interdune land and windward slopes of the fixed sand dunes, and the al- gal-dominated BSCs on the crest and leeward slopes. Soil water retention capacity and hydraulic conductivity were measured using an indoor evaporation method and a field infiltration method. And the results were fitted to the van Genuchten-Mualem model. Unsaturated hydraulic conductivities under greater water pressure (〈-0.01 MPa) and water retention capacities in the entire pressure head range were higher for both crust types than for bare sand. However, saturated and unsaturated hydraulic conductivities in the near-saturation range (〉-0.01 MPa) showed decreasing trends from bare sand to moss crusts and to algal crusts. Our data suggested that topographic differentiation of BSCs significantly affected not only soil water retention and hydraulic conductivities, but also the overall hydrology of the fixed sand dunes at a landscape scale, as seen in the reduction and spatial variability in deep soil water storage.展开更多
Biological soil crusts (BSCs) are capable of modifying nutrient availability to favor the establishment of biogeochemical cycles. Microbial activities serve as critical roles for both carbon and nutrient transformat...Biological soil crusts (BSCs) are capable of modifying nutrient availability to favor the establishment of biogeochemical cycles. Microbial activities serve as critical roles for both carbon and nutrient transformation in BSCs. However, little is known about microbial activities and physical-chemical properties of BSCs in the Gurbantunggut Desert, Xinjiang, China. In the present research, a sampling line with 1-m wide and 20-m long was set up in each of five typical interdune areas selected randomly in the Gurbantunggut Desert. Within each sampling line, samples of bare sand sheet, algal crusts, lichen crusts and moss crusts were randomly collected at the depth of 0-2 cm. Varia- tions of microalgal biomass, microbial biomass, enzyme activities and soil physical-chemical properties in different succession of BSCs were analyzed. The relationships between microalgal biomass, microbial biomass, enzymatic activities and soil physical-chemical properties were explored by stepwise regression. Our results indicate that micro- algal biomass, microbial biomass and most of enzyme activities increased as the BSCs developed and their highest values occurred in lichen or moss crusts. Except for total K, the contents of most soil nutrients (organic C, total N, total P, available N, available P and available K) were the lowest in the bare sand sheet and significantly increased with the BSCs development, reaching their highest values in moss crusts. However, pH values significantly decreased as the BSCs developed. Significant and positive correlations were observed between chlorophyll a and microbial biomass C. Total P and N were positively associated with chlorophyll a and microbial biomass C, whereas there was a significant and negative correlation between microbial biomass and available P. The growth of cyanobacteria and microorganism contributed C and N in the soil, which offered substrates for enzyme activities thus increasing enzyme activities. Probably, improvement in enzyme activities increased soil fertility and promoted the growth of cyanobacteria, eukary- otic algae and heterotrophic microorganism, with the accelerating succession of BSCs. The present research found that microalgal-microbial biomass and enzyme activities played important roles on the contents of nutrients in the successional stages of BSCs and helped us to understand developmental mechanism in the succession of BSCs.展开更多
Biological soil crusts (BSCs) are an important type of land cover in arid desert landscapes and play an important role in the carbon source-sink exchange within a desert system. In this study, two typical BSCs, moss...Biological soil crusts (BSCs) are an important type of land cover in arid desert landscapes and play an important role in the carbon source-sink exchange within a desert system. In this study, two typical BSCs, moss crusts and algae crusts, were selected from a revegetated sandy area of the Tengger Desert in northern China, and the experiment was carried out over a 3-year period from January 2010 to November 2012. We obtained the effec- tive active wetting time to maintain the physiological activity of BSCs basing on continuous field measurements and previous laboratory studies on BSCs photosynthesis and respiration rates. And then we developed a BSCs carbon fixation model that is driven by soil moisture. The results indicated that moss crusts and algae crusts had significant effects on soil moisture and temperature dynamics by decreasing rainfall infiltration. The mean carbon fixation rates of moss and algae crusts were 0.21 and 0.13 g C/(m2.d), respectively. The annual carbon fixations of moss crusts and algae crusts were 64.9 and 38.6 g C/(m2.a), respectively, and the carbon fixation of non-rainfall water reached 11.6 g C/(m2.a) (30.2% of the total) and 8.8 g C/(m2.a) (43.6% of the total), respectively. Finally, the model was tested and verified with continuous field observations. The data of the modeled and measured CO2 fluxes matched notably well. In desert regions, the carbon fixation is higher with high-frequency rainfall even the total amount of seasonal rainfall was the same.展开更多
Many seamounts are covered with cobalt-rich ferromanganese crusts,and are increasingly attracting interest for the potential extraction of valuable mineral resources from deep seabed environments.However,the impacts o...Many seamounts are covered with cobalt-rich ferromanganese crusts,and are increasingly attracting interest for the potential extraction of valuable mineral resources from deep seabed environments.However,the impacts of potential mining activities on the vulnerable seamount ecosystem remain unclear.To enhance the understanding of connectivity in benthic invertebrate populations in the Northwest Pacific,several seamounts were surveyed and biological samples collected.In the present study,the ophiuroid species Ophioplinthaca defensor is reported for the first time from four deep seamounts in the Northwest Pacific,and described,providing more detailed morphological diagnosis characters.To assess the population structure of the species between and within seamounts,two mitochondrial markers(COI and 16 S)were sequenced.In total,20 haplotypes from 32 COI sequences and 8 haplotypes from 3716 S sequences were recovered.The star-shaped TCS networks and nonsignificant pairwise population differences reveal the absence of distinct population structures between and within seamounts.In addition,the O.defensor population seemed to have undergone a demographic expansion in history.This is the first study on the genetic population structure of a benthic invertebrate from seamounts in the Northwest Pacific,and this results suggest a potentially high,long distance dispersal capacity in O.defensor between seamounts,which could inform the development of the Regional Environmental Management Plans for the cobalt-rich crust seamounts in the area.展开更多
Based on the survey data of five submarine seamount provinces (chains) in the Western Pacific, the distribution characteristics of cobalt-rich ferromanganese crust resources have been researched in this paper by usi...Based on the survey data of five submarine seamount provinces (chains) in the Western Pacific, the distribution characteristics of cobalt-rich ferromanganese crust resources have been researched in this paper by using the relative reference data and applying the theories of hotspot and seafloor spreading. The main research results obtained are as follows: The Co-rich crust thickness in the study area is gradually increasing from east to west and from south to north having a negative correlation (r = -0.59) with longitude and a positive correlation (r = 0.48) with latitude. The crust thickness varying along longitude and latitude is influenced by the hotspot and seafloor spreading. The oceanic crusts and seamounts in the northwest part of the study area are older, and the crust resources are superior to those in the southeast part. In the depth of 〈1500 m, 1500-2000 m, 2000-2500 m in the study area, the cobalt crust thickness is respectively 5.45 cm, 4.34 cm and 3.55 cm, and in the depth of 2500-3000 m and 3000-3500 m, it drops respectively to 2.84 cm and 3.37 cm. The Co-rich crust resources are mainly concentrated in the seamount summit margins and the upper flanks in the depth of 〈2500 m. There is a strong negative correlation (r = -0.67) between the cobalt crust abundance and the slope of the seamount, 75 kg/m^2 and 50 kg/mz at the slopes of 0°-20° and 20°-34° respectively. Cobalt crusts are mainly distributed in the parts whose slopes are less than 20°. It is consistent with the fractal result that the slope threshold of cobalt crust distribution is 19°, and slopes over 20° are not conducive to the crust growth. The cobalt crusts of high grade are mainly enriched in the region within 150°E-140°W and 30°S-30°N in the Pacific, where there are about 587 seamounts at the depth of 3500- 6000 m and over 30 Ma of the oceanic crusts. The perspective area rich in cobalt crust resources is about 41×104 km^2 and the resource quantity is approximately 27 billion tons.展开更多
基金This study was supported by Projects under contract Nos DY105 China's 0cean-03-01-01 and DY105-03-01-07the National Natural Science Foundation of China under contract No.40506017the Youth Foundation of Marine High-tech Project of China under contract No.2002AA616010.
文摘On the basis of three geological models and several orebody boundaries, a method of grid subdivision and integral has been proposed to calculate and evaluate the resources of cobalt-rich crusts on the seamounts in the central Pacific Ocean. The formulas of this method are deduced and the interface of program module is designed. The method is carried out in the software "Auto mapping system of submarine topography and geomorphology MBChart". This method and program will possibly become a potential tool to calculate the resources of seamounts and determine the target diggings for China' s next Five-year Plan.
基金supported by the National Natural Science Foundation of China(40704029 40376016)+1 种基金China International Science and Technology Cooperation Project (2006DFB21620)the Young People Marine Science Foundation of State Oceanic Administration (2005304)
文摘Rare earth elements(REEs) and major elements of 25 cobalt-rich crusts obtained from different depths of Mid-Pacific M seamount were analyzed using inductively coupled plasma-atomic emission spectrometer and gravimetric method.The results showed that they were hydrogenous crusts with average ∑REE content of 2084.69 μg/g and the light REE(LREE)/heavy REE(HREE) ratio of 4.84.The shale-normalized REE patterns showed positive Ce anomalies.The total content of strictly trivalent REEs increased with water depth.The Ce content and LREE/HREE ratios in Fe-Mn crusts above 2000 m were lower than those below 2000 m.The change in REE with water depth could be explained by two processes:adsorptive scavenging by setting matters and behaviors of REE in seawater.However, the Ce abundance took no obvious correlation with water depth reflects the constant Ce flux.The Ce in crusts existed mainly as Ce(IV), implying that the oxidative-enriching process was controlled by kinetic factors.
基金supported by National Natural Science Foundation of China (Grant Nos. 41076072 and 40676025)
文摘A biostratigraphic study on calcareous nannofossils from the CM3D06 Co-rich ferromanganese crust from the Magellan seamounts in the northwestern Pacific enabled estimation of depositional age. The bio-imprinting of calcareous nannofossils and other fossil species suggests six age ranges for the nannofossils: late Cretaceous, late Paleocene, (early, middle, late) Eocene, middle Miocene, late Pliocene, and Pleistocene. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were used to test the Co-rich crusts, and a variety of molecular fossils were detected, such as chloroform bituminous "A" , n-alkane, isoprenoid and sterol. Peak carbon and molecular indices (such as C23-/C24+, CPI, Pr/Ph, Pr/nC17, Ph/nCxs and j13C) indicate that the parent organic matter is dominated by marine phytoplankton and thallogen whereas there is little input of terrestrial organic matter. Researches on calcareous nannofossils, molecular fossils and molecular organic geochemistry data reveal that the Paleocene/Eocene (P/E) global event is recorded in the cobalt- rich crusts from the northwestern Pacific Ocean. A succession of biomes can be observed near the 85 mm boundary (about 55 Ma), i.e., the disappearance of the late Cretaceous Watznaueria barnesae and Zigodicus spiralis, and Broisonia parka microbiotas above the P/E boundary, and the bloom of Coccolithus formosus, Discoaster multiradiatus, Discoaster mohleri and Discoaster sp. below the boundary. Typical parameters of molecular fossils, such as saturated hydrocarbon components and carbon-number maxima, Pr/Ph, Pr/C17, Ph/C18, distribution types of sterols, Ts/Tm ratios and bacterial hopane, also exhibit dramatic changes near the P/E boundary. These integrated results illustrate that the biome succession of calcareous nannofossils, relative content of molecular fossils and molecular indices in the cobalt-rich crusts near the 85 mm boundary faithfully record the P/E global event.
基金The National Natural Science Foundation of China(NSFC)under contract Nos 41076072 and 40676025the Shandong Provincial Natural Science Foundation under contract No.ZR2011EMQ010
文摘Organic matter in cobalt-rich crust (CRC) from the Marcus-Wake Seamounts of the western Pacific Ocean, Sample CM1D03, has been analyzed to understand the source, geochemistry and mineralization of organic matter, and the mineralization environment. Biomarkers, includingn-alkanes, isoprenoids, terpanes and sterols, have been detected in various layers of the CRC sample, using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The content of organic carbon (OC) and its stable isotope (δ13C), and the combined features of the biomarkers show that the mineralized organic matter in CM1D03 CRC was mainly derived from microorganisms and lower plankton (e.g., bacteria and algae, respectively) from marine surface water, with some terrestrial higher plant components. The ratio of chloroform bitu-men "A": OC was high in the CRC, between 10.51 and 20.66, showing significant migration characteristics of n-alkanes. Four mineralization categories of organic matter were recognized based on GC chromatograms ofn-alkane molecules: (1) primitive type (bacteria and algae), which is characterized by moderately mature ofn-alkanes preserving the original characteristics of the organic matter from microorganisms and lower plankton; (2) microbial degradation type, which is characterized by low contents ofn-alkanes and rising baseline in the chromatogram, with the "bulge" being the products of organic matter by biodegradation; (3) organic matter migration type, which is characterized by low carbon number ofn-alkanes withnC18 as the main peak carbon, without odd even predominance, and low concentrations of isoprenoids and hydro-carbons with high carbon number; and (4) organic matter hydrothermal type, which is characterized by relatively low concentration of small molecular weightn-alkanes, pristane, and phytane, accompanied by higher concentration ofn-alkanes with carbon number greater thannC18. This study shows that biomarkers can record controlling factors of mineralization and their variation.
基金funded by the National Key R&D Program of China (2022YFB4202102)the Key R&D Program of Ningxia Hui Autonomous Region (2022BEG02003)the Excellent Member of Youth Innovation Promotion Association CAS (No.Y202085)。
文摘The Qinghai-Tibet Plateau is now experiencing ecological degradation risks as a result of climate change and human activities.The alpine grassland ecology in permafrost zones is fragile and susceptible to deterioration due to its high altitude,low temperature,and limited oxygen,which complicates the repair of damaged land.Biological soil crusts(BSCs)are crucial for land restoration in plateau regions because they can thrive in harsh conditions and have environmentally beneficial traits.Inoculated biological soil crust(IBSC)has shown success in low-altitude desert regions,but may not be easily duplicated to the plateau environment.Therefore,it is essential to do a comprehensive and multifaceted analysis of the basic theoretical comprehension and practical application of BSCs on the Tibetan Plateau.This review article aims to provide a brief summary of the ecological significance and the mechanisms related to the creation,growth,and progression of BSCs.It discusses the techniques used for cultivating BSCs in laboratories and using them in the field,focusing on the Qinghai-Tibet Plateau circumstance.We thoroughly discussed the potential and the required paths for further studies.This study may be used as a basis for selecting suitable microbial strains and accompanying supplemental actions for implementing IBSCs in the Qinghai-Tibet Plateau.
基金funded by the National Natural Science Foundation of China (42067013, 41571090)
文摘Globally,many lakes are drying up,leaving exposed lakebeds where wind erosion releases dust and sand rich in salt and harmful heavy metals into the atmosphere.Therefore,understanding the characteristics and spatial distribution of playa surface crusts is important to recognize the manifestation of salt dust storms.The objective of this study was to explore the playa surface crust types as well as their spatial distribution and evolution of Qehan Lake in Inner Mongolia Autonomous Region,China to understand the salt dust release potential of different types of playa surface crusts.Various crust characteristics were investigated by field sampling in Qehan Lake,and playa surface crusts were further divided into five types:vegetated areas,salt crusts,clay flats,curly crusts,and margins.It should be noted that curly crusts were distributed in clay flats and covered only a small area in Qehan Lake.The spatial distribution characteristics of playa surface crust types were obtained by supervised classification of remote sensing images,and the salt dust release potential of crusts was explored by the wind tunnel experiments.The field investigation of Qehan Lake revealed that playa surface crust types had a circum-lake band distribution from the inside to the outside of this lake,which were successively vegetated areas,clay flats,salt crusts,and margins.The spatial distribution patterns of playa surface crust types were mainly controlled by the hydrodynamics of the playa,soil texture,and groundwater.There was a significant negative correlation between crust thickness and electrical conductivity.The results of the wind tunnel experiments showed that the initial threshold of friction wind velocity for the salt dust release was higher in clay flats(0.7–0.8 m/s)than in salt crusts(0.5–0.6 m/s).Moreover,the particle leap impact processes occurring under natural conditions may reduce this threshold value.Salinity was the main factor controlling the difference in the initial threshold of friction wind velocity for the salt dust release of clay flats and salt crusts.This study provides a scientific reference for understanding how salt dust is released from a lakebed,which may be used for ecological restoration of dry salt lakes.
基金China International Seabed Area R & D Program under contract No.DYXM-115-01-1
文摘In 2001, the International Seabed Authority (ISBA) initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crusts in the Area at its 7th session. Since then, the consideration of the Regulations has been mainly focused on the size of areas to be allocated for exploration and exploitation of the crusts. This paper, based on the investigation data and the analysis of the distribution characteristics of the crusts, suggests a model for determining the size of areas for exploration and exploitation of the crusts, taking into account various factors such as production scale, crust thickness and grade, mineable area proportion, recovery efficiency, exploration venture, and so on. Through the modeling, the paper suggests that the exploration area (the area covered by each application for approval of a plan of work for exploration of cobalt-rich crusts) shall be 4 856 km2 and the exploitation area (the mine site area) shall be 1 214 km2, for 20 years of 1 million wet tonnes annual production.
文摘Noble gas isotopic compositions of various layers in three-layered (outer, porous and compact layers) cobalt-rich ferromanganese crusts and their basaltic and phosphorite substrates from the western Pacific Ocean were analyzed by using a high vacuum gas mass spectrum. The analytical results show that the noble gases in the Co-rich crusts have derived mainly from the ambient seawater, extraterrestrial grains such as interplanetary dust particles (IDPs) and wind-borne continental dust grains, and locally formation water in the submarine sediments, but different noble gases have different sources. He in the crusts derives predominantly from the extraterrestrial grains, with a negligible amount of radiogenic He from the eolian dust grains. Ar is sourced mainly from the dissolved air in the seawater and insignificantly from radiogenic Ar in the eolian continental dust grains or the formation water. Xe and Ne derive mainly from the seawater, with minor amounts of extraterrestrial Xe and Ne in the IDPs. Compared with the porous and outer layers, the compact layer has a relatively high 4He content and lower 3He/4He ratios, suggesting that marine phosphatization might have greatly modified the noble gas isotopic compositions of the crusts. Besides, the 3He/4He values of the basaltic substrates of the cobalt-rich crusts are very low and their R/R. ratios are mostly 〈0.1 R., which are similar to that of phosphorite substrates (0.087 R.), but much lower than that of fresh submarine MORB (8.75±14 Ra) or seamount basalts (3-43 Ra), implying that the basaltic substrates have suffered strong water/rock interaction and reacted with radiogenic ^4He and P-rich upwelling marine currents during phosphatization. The trace elements released in the basalt/seawater interaction might favor the growth of cobalt-rich crusts. The relatively low ^3He/^4He values in the seamount basalts may be used as an important exploration criterion for the cobalt-rich ferromanganese crusts.
基金This work was sponsored by the International Ocean Area Research & Development Tenth Five-Year Plan Programme (Grant No. DY105-04-01-9).
文摘An ammonia leaching process was utilized to extract Co, Ni and Cu from oceanic polymetallic nodules, whereas an acid leaching process was utilized to extract Co, Ni, Cu, Zn and Mn from cobalt-rich crusts. Both processes produced nanometer materials-ammonia leaching residue and acid leaching residue. A systematic study was conducted on the phase, composition and physicochemistry properties of these residues. The result shows that both residues contain a large amount of nanometer minerals. Ammonia leaching residue mainly consists of rhodochrosite, with the average grain diameter of 17.9 nm; whereas the acid leaching residue mainly consists of well-developed bassanite, with the average grain deameter of 9.5 nm. The bassanite also has a microporous structure, the volume of the pore space is 1.23×10-2 mL/g. Both the ammonia and acid leaching residues have a large specific surface area, and they display a strong adsorption capacity to saturate sodium chloride vapour, N2 and SO2. Both residues have high
基金supported by grant DY95-08-05 from the China Ocean Mineral Resources R&D Associationthe National Natural Science Foundation of China(Grant 40373002).
文摘A detailed study on a small scale of the effect of phosphatization on the chemistry of marine cobalt-rich ferromanganese crusts supplies useful information for the evaluation and comprehensive utilization of crust mineral resources. Sub-samples from top to bottom of a 10-cm thick sample from the NW Pacific Magellan seamount were taken at 5 mm intervals. The concentration profiles of ore-forming and rare earth elements show that obvious differences exist between young unphosphatized crusts and old phosphatized crusts. In the old crusts Fe, Mn, Si, Al, Zn, Mg, Co, Ni and Cu elements are depleted and Ca, P, Sr, Ba and Pb elements are enriched. The order of depletion is Co > Ni > Mg > Al > Mn > Si> Cu > Zn > Fe, while the order of enrichment is P > Ca > Ba > Pb > Sr. The phosphate mineral controls the concentration variation of the ore-forming elements in crusts and causes loss of the main ore-forming elements such as Co and Ni. The phosphatization also affects the abundance of REEs in the crusts. REEs are more abundant and the content of Ce in old crusts is higher than that in young crusts, however, the pattern of REEs and their fractionation characteristics in new and old crusts are not fundamentally changed. A Y-positive anomaly in old crusts has no relationship to the phosphatization.
基金supported by the National Natural Science Foundation of China(Grant Nos.41076072 and 40676025)
文摘Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous(more than 70.0 Ma). There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossils preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene(E/O) transition. The results show the transitions and recombination of species in the biotic community during the E/O transition obviously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change.
基金funded by the National Basic Research Program of China (2013CB429901)the National Natural Science Foundation of China (41471434, 31170385)the Foundation for Excellent Youth Scholars of CAREERI, Chinese Academy of Sciences
文摘Biological soil crusts (BSCs) play an important role in surface soil hydrology. Soils dominated with moss BSCs may have higher infiltration rates than those dominated with cyanobacteria or algal BSCs. However, it is unnown whether improved infiltration in moss BSCs is accompanied by an increase in soil hydraulic conductivity or water retention capacity. We investigated this question in the Tengger Desert, where a 43-year-old revegetation program has promoted the formation of two distinct types of BSCs along topographic positions, i.e. the moss-dominated BSCs on the interdune land and windward slopes of the fixed sand dunes, and the al- gal-dominated BSCs on the crest and leeward slopes. Soil water retention capacity and hydraulic conductivity were measured using an indoor evaporation method and a field infiltration method. And the results were fitted to the van Genuchten-Mualem model. Unsaturated hydraulic conductivities under greater water pressure (〈-0.01 MPa) and water retention capacities in the entire pressure head range were higher for both crust types than for bare sand. However, saturated and unsaturated hydraulic conductivities in the near-saturation range (〉-0.01 MPa) showed decreasing trends from bare sand to moss crusts and to algal crusts. Our data suggested that topographic differentiation of BSCs significantly affected not only soil water retention and hydraulic conductivities, but also the overall hydrology of the fixed sand dunes at a landscape scale, as seen in the reduction and spatial variability in deep soil water storage.
基金financially supported by the National Natural Science Foundation of China (41071041, U1203301)the West Light Foundation of Chinese Academy of Sciences (RCPY201101)
文摘Biological soil crusts (BSCs) are capable of modifying nutrient availability to favor the establishment of biogeochemical cycles. Microbial activities serve as critical roles for both carbon and nutrient transformation in BSCs. However, little is known about microbial activities and physical-chemical properties of BSCs in the Gurbantunggut Desert, Xinjiang, China. In the present research, a sampling line with 1-m wide and 20-m long was set up in each of five typical interdune areas selected randomly in the Gurbantunggut Desert. Within each sampling line, samples of bare sand sheet, algal crusts, lichen crusts and moss crusts were randomly collected at the depth of 0-2 cm. Varia- tions of microalgal biomass, microbial biomass, enzyme activities and soil physical-chemical properties in different succession of BSCs were analyzed. The relationships between microalgal biomass, microbial biomass, enzymatic activities and soil physical-chemical properties were explored by stepwise regression. Our results indicate that micro- algal biomass, microbial biomass and most of enzyme activities increased as the BSCs developed and their highest values occurred in lichen or moss crusts. Except for total K, the contents of most soil nutrients (organic C, total N, total P, available N, available P and available K) were the lowest in the bare sand sheet and significantly increased with the BSCs development, reaching their highest values in moss crusts. However, pH values significantly decreased as the BSCs developed. Significant and positive correlations were observed between chlorophyll a and microbial biomass C. Total P and N were positively associated with chlorophyll a and microbial biomass C, whereas there was a significant and negative correlation between microbial biomass and available P. The growth of cyanobacteria and microorganism contributed C and N in the soil, which offered substrates for enzyme activities thus increasing enzyme activities. Probably, improvement in enzyme activities increased soil fertility and promoted the growth of cyanobacteria, eukary- otic algae and heterotrophic microorganism, with the accelerating succession of BSCs. The present research found that microalgal-microbial biomass and enzyme activities played important roles on the contents of nutrients in the successional stages of BSCs and helped us to understand developmental mechanism in the succession of BSCs.
基金supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (KZCX2-EW-301-3)the National Program on Key Basic Research Project (2013CB429905)+1 种基金the National Natural Scientific Foundation of China (41201084 31170385)
文摘Biological soil crusts (BSCs) are an important type of land cover in arid desert landscapes and play an important role in the carbon source-sink exchange within a desert system. In this study, two typical BSCs, moss crusts and algae crusts, were selected from a revegetated sandy area of the Tengger Desert in northern China, and the experiment was carried out over a 3-year period from January 2010 to November 2012. We obtained the effec- tive active wetting time to maintain the physiological activity of BSCs basing on continuous field measurements and previous laboratory studies on BSCs photosynthesis and respiration rates. And then we developed a BSCs carbon fixation model that is driven by soil moisture. The results indicated that moss crusts and algae crusts had significant effects on soil moisture and temperature dynamics by decreasing rainfall infiltration. The mean carbon fixation rates of moss and algae crusts were 0.21 and 0.13 g C/(m2.d), respectively. The annual carbon fixations of moss crusts and algae crusts were 64.9 and 38.6 g C/(m2.a), respectively, and the carbon fixation of non-rainfall water reached 11.6 g C/(m2.a) (30.2% of the total) and 8.8 g C/(m2.a) (43.6% of the total), respectively. Finally, the model was tested and verified with continuous field observations. The data of the modeled and measured CO2 fluxes matched notably well. In desert regions, the carbon fixation is higher with high-frequency rainfall even the total amount of seasonal rainfall was the same.
基金The National Natural Science Foundation of China under contract No.42076135the Foundation of China Ocean Mineral Resources R&D Association under contract Nos DY135-E2-2-06 and DY135-E2-2-03+1 种基金the Project of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,Ministry of Natural Resources,under contract No.SOEDZZ2002the Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,under contract No.JG1528
文摘Many seamounts are covered with cobalt-rich ferromanganese crusts,and are increasingly attracting interest for the potential extraction of valuable mineral resources from deep seabed environments.However,the impacts of potential mining activities on the vulnerable seamount ecosystem remain unclear.To enhance the understanding of connectivity in benthic invertebrate populations in the Northwest Pacific,several seamounts were surveyed and biological samples collected.In the present study,the ophiuroid species Ophioplinthaca defensor is reported for the first time from four deep seamounts in the Northwest Pacific,and described,providing more detailed morphological diagnosis characters.To assess the population structure of the species between and within seamounts,two mitochondrial markers(COI and 16 S)were sequenced.In total,20 haplotypes from 32 COI sequences and 8 haplotypes from 3716 S sequences were recovered.The star-shaped TCS networks and nonsignificant pairwise population differences reveal the absence of distinct population structures between and within seamounts.In addition,the O.defensor population seemed to have undergone a demographic expansion in history.This is the first study on the genetic population structure of a benthic invertebrate from seamounts in the Northwest Pacific,and this results suggest a potentially high,long distance dispersal capacity in O.defensor between seamounts,which could inform the development of the Regional Environmental Management Plans for the cobalt-rich crust seamounts in the area.
基金This work was supported by grant 2004DIB3J086 and 2006FY220400 from the State Ministry of Science and Technology; the National Natural Science Foundation of China (Grant 40676061) ; China Ocean Resource R&D Association (Grant DYXM- 115-01-1-06).
文摘Based on the survey data of five submarine seamount provinces (chains) in the Western Pacific, the distribution characteristics of cobalt-rich ferromanganese crust resources have been researched in this paper by using the relative reference data and applying the theories of hotspot and seafloor spreading. The main research results obtained are as follows: The Co-rich crust thickness in the study area is gradually increasing from east to west and from south to north having a negative correlation (r = -0.59) with longitude and a positive correlation (r = 0.48) with latitude. The crust thickness varying along longitude and latitude is influenced by the hotspot and seafloor spreading. The oceanic crusts and seamounts in the northwest part of the study area are older, and the crust resources are superior to those in the southeast part. In the depth of 〈1500 m, 1500-2000 m, 2000-2500 m in the study area, the cobalt crust thickness is respectively 5.45 cm, 4.34 cm and 3.55 cm, and in the depth of 2500-3000 m and 3000-3500 m, it drops respectively to 2.84 cm and 3.37 cm. The Co-rich crust resources are mainly concentrated in the seamount summit margins and the upper flanks in the depth of 〈2500 m. There is a strong negative correlation (r = -0.67) between the cobalt crust abundance and the slope of the seamount, 75 kg/m^2 and 50 kg/mz at the slopes of 0°-20° and 20°-34° respectively. Cobalt crusts are mainly distributed in the parts whose slopes are less than 20°. It is consistent with the fractal result that the slope threshold of cobalt crust distribution is 19°, and slopes over 20° are not conducive to the crust growth. The cobalt crusts of high grade are mainly enriched in the region within 150°E-140°W and 30°S-30°N in the Pacific, where there are about 587 seamounts at the depth of 3500- 6000 m and over 30 Ma of the oceanic crusts. The perspective area rich in cobalt crust resources is about 41×104 km^2 and the resource quantity is approximately 27 billion tons.
基金supported by the Key Knowledge Innovation Project of the Chinese Academy of Sciences (KZCX2-YW-336)the National Natural Science Foundation of China (40771114)