The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg...The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg/g with the change of depth,which was divided into three distribution types as follows:TN content decreases gradually with the increase of depth,TN content increases gradually with the increase of depth or higher content in the middle but lower content in two ends.NH4+-N content ranged from 8.7 ...展开更多
Study on form characteristics of nitrogen in marine sediments is the primary method to research its biogeochemical cycling and nitrogen form characteristics in core sediments can reflect the process and results of ear...Study on form characteristics of nitrogen in marine sediments is the primary method to research its biogeochemical cycling and nitrogen form characteristics in core sediments can reflect the process and results of early diagenesis in a certain degree. In this paper, Sequential extraction process in natural grain size was used for studying the existent forms of nitrogen in five core sediments of the southern Bohai Sea for the first time. Nitrogen was divided into two parts - transferable and fixed based on whether it could be extracted by the reagent. Distributions and early diagenesis of transferable nitrogen forms in the southern Bohai Sea were researched integratedly. Results indicate that IEF - N and OSF-N are predominant forms in transferable part in the studied core sediments. Contents of different nitrogen forms vary differently with depth, and have different diagenesis process. Decomposition constant of organic nitrogen (ON) and OC are about 15.51 -× 10^(-3)a^(-3)and 4.79× 10^(-3)a^(-1) respectively, and the decomposition content of biogenic elements C, N, P, Si has the sequence N>P>CSi. OC/TN (simplified as C/N in the following) ratio is much lower than OC/ON, which indicates that sediment preserves plenty of inorganic nitrogen (IN) and/or fixed nitrogen, and the decrease of OC/ON ratio with depth is due to ON reservation in sediments. Generally, transferable nitrogen accounts for more proportion of TN in the surface layer than in the deep layer of core sediments, whereas, some stable forms of nitrogen can activate and become transferable under appropriate environment, which induces the proportion of transferable nitrogen in TN in the deep layer to be almost the same as that in the surface layer.展开更多
The concentration of zinc, chromium, cadmium, nickel, lead and copper was measured on both surface sediments and core sediments in the Shenzhen Bay. The average contents of all metals have exceeded the background valu...The concentration of zinc, chromium, cadmium, nickel, lead and copper was measured on both surface sediments and core sediments in the Shenzhen Bay. The average contents of all metals have exceeded the background values in the coastal zone of Guangdong Province. Cadmium is a heavy pollution matter which indicates a strong pollution level according to the ecological risk coefficient method. The ecological risk index of the whole area is 299 which belongs to middle and strong level. The area with strong pollution level is the near shore area closing to the inside of Shenzhen Bay, Shakou area is in the middle level while the weak pollution level occurs in Shenzhenhe Estuary according to ecological risk index. The four sediment cores can be divided into two parts based on lead-210 dating, sediments size analysis and economic development period in surrounding areas since 1950 with strong human intervention. The sediment size, deposition rate and human activities have positive relationship with the contents of heavy metals which directly impact the pollution level of heavy metals in sediments in Shenzhen Bay.展开更多
Sequential core sediments from northwestern Taihu Lake in China were analyzed for grain size, organic carbon and heavy metal content. The sediments are composed of organic-poor clayey-fine silts. The chemical speciati...Sequential core sediments from northwestern Taihu Lake in China were analyzed for grain size, organic carbon and heavy metal content. The sediments are composed of organic-poor clayey-fine silts. The chemical speciations of Cu, Fe, Mn, Ni, Pb, and Zn were also analyzed using the BCR sequential extraction procedure. Cu, Fe, Ni, and Zn are mainly associated with the residue fraction; Mn is concentrated mainly in exchangeable/carbonate fraction and residue fraction; and Pb mainly in Fe/Mn oxide fraction and organic/sulfide fraction. The exchangeable/carbonate fractions of Cu, Fe, Ni, Zn and Pb are lower. The fractions of Ni, Pb and Zn bound to the Fe/Mn oxide have significant correlations with reducible Mn; the organic/sulfide fractions of Cu, Mn, Ni, Pb, and Zn have significant correlations with TOC. The extractable fractions of Cu, Mn, Ni, Pb, and Zn are high at the top 4 cm of the core sediments as compared to those in the deeper layers, showing the anthropogenic input of heavy metals is due to rapid industrial development. The heavy metal pollution history of the sediments has been recorded since the late 1970s, determined by the result of {{}+{137}Cs} dating.展开更多
Protoporphyrin Ⅸ(PPⅨ), a basic porphyrin system found in nature, all “porphyrin-type”tetrapyrroles with a biological function are biosynthetically derived thereof. PPⅨ is a metalloprosthetic group of numerous pro...Protoporphyrin Ⅸ(PPⅨ), a basic porphyrin system found in nature, all “porphyrin-type”tetrapyrroles with a biological function are biosynthetically derived thereof. PPⅨ is a metalloprosthetic group of numerous proteins involved in diverse metabolic and respiratory processes across all domains of life, and is thus considered essential for respiring organisms. Determining the biotic and abiotic factors that influence marine microbial growth and community structure is critical for understanding global biogeochemical cycles. Here,we present vertical profiles of intracellular PPⅨ and four derivative products(Chlorophylla/b and Pheophytin-a/b) from two coastal sediment cores, alongside ancillary geochemical and 16S rRNA microbial community data. Our findings indicated that PPⅨ is present in the natural sediment environment and displays a decreasing trend with depth, revealing a significant positive correlation with both organic matter and microbial abundance. Cooccurrence networks revealed that the environmental distribution of PPⅨ was positively correlated with the microbial porphyrin producer(high genetic completeness), but negatively correlated with auxotrophs(absence or low genetic completeness). It emphasized the critical role of PPⅨ as a biological molecule involved in key physiological processes. These results suggest that PPⅨ is a prominent component of the shared extracellular metabolite pool, especially in anoxic marine sediments where it exists at physiologically relevant concentrations for microbial metabolism. This study highlighted the significance of PPⅨ in microbial ecology and its potential impact on biogeochemical cycles in marine sedimentary environments.展开更多
Samples were collected from two core sediments(C1 and C2) of Xiangjiang River,Chang-Zhu-Tan region,Hunan Province,China.The heavy metal contents are relatively higher,especially for the surface or near the surface lay...Samples were collected from two core sediments(C1 and C2) of Xiangjiang River,Chang-Zhu-Tan region,Hunan Province,China.The heavy metal contents are relatively higher,especially for the surface or near the surface layers.The calculated anthropogenic factor values indicate that all the heavy metals except for Cr in the core samples are enriched,especially for Cd,with the maximum enriching coefficients of 119.44,and 84.67 in C1 and C2,respectively.The correlation of heavy metals with sulphur indicates that they are precipitated as metal sulphides.Correlation matrix shows significant association between heavy metals and mud.Factor analysis identifies that signified anthropogenic activities affect the region of Xiangjiang River.展开更多
The western Bay of Bengal is particularly susceptible to the harmful impacts of increasing coastal pollution,as coastal population and urban development are occurring at unprecedented rates.The rapid urbanization and ...The western Bay of Bengal is particularly susceptible to the harmful impacts of increasing coastal pollution,as coastal population and urban development are occurring at unprecedented rates.The rapid urbanization and industrialization along the east coast of India coupled with the transfer of contaminants into the Bay of Bengal through riverine systems,causing a direct impact on marine ecosystems.In the present study,an attempt has been made to understand the heavy metal distribution on shelf sediments in the western part of the Bay of Bengal to infer their source,processes,and historical changes in marine pollution.Three short sediment core samples were collected and analysed for sediment texture,organic matter,and heavy metals.Cores 1 and 2 contain a high amount of sand content,representing shallow marine with moderate to high-energy conditions,and were deposited at a recent time.Core 3 was dominated by muddy sand to sandy mud,which denotes calm sedimentation without any turbulence,and these sediments were deposited under relatively low-energy conditions.The higher concentration of organic matter in the top layers of the core indicates both marine and terrestrial input.The heavy metal contents show quite heterogeneous and variable distributions from one element to another and from one core to another.The calculated pollution indices such as Contamination Factor(CF),and Geoaccumulation Index(Igeo)and Pollution Load Index(PLI)values indicate that all the core sub-samples are severely enriched and highly polluted by Cd and moderately polluted by Pb.The increased heavy metal concentration in the upper portion of the sediment cores and moderate to considerable ecological risks indicate that these metals have been deposited in the study area for the past few decades.展开更多
Three sediment cores were collected in November 2003 from Dagu estuary to Qikou estuary. The main polluted heavy metals in the sediment of tidal zones for the Bohai Bay have been found by analyzing the relationship am...Three sediment cores were collected in November 2003 from Dagu estuary to Qikou estuary. The main polluted heavy metals in the sediment of tidal zones for the Bohai Bay have been found by analyzing the relationship among the contents of heavy metals, the contents of geochemical elements （Fe, AI and Mn） and the size of grain. The dominating contaminative elements in tidal sediments of Bohai Bay are Pb, Zn and Cd. Their contents are higher than the corresponding upper limit of environmental background values and they have very faint correlation with the corresponding contents of geochemical elements and the size of grain, indicating the anthropogenic enrichment. Especially, the preliminary study on the pollution sources and the history of heavy metals in the Dagu estuary has been done using the dated results. The contamination by Zn and Cd also started in the middle 1950s, while the contamination by Pb appeared in the early 1940s. The pollution by Zn and Cd mainly originate from sewage discharge, while the pollution by Pb has many sources, like atmosphere deposition and industrial discharRe.展开更多
The cored sediments sampled by R/V Marion Dufrense in the active margin off southwestern Taiwan on the east side of the Manila Trench are mostly muds consisting mainly of quartz, feldspar, illite, chlorite ＋ kaolinit...The cored sediments sampled by R/V Marion Dufrense in the active margin off southwestern Taiwan on the east side of the Manila Trench are mostly muds consisting mainly of quartz, feldspar, illite, chlorite ＋ kaolinite with a trace amount of montmorillonite. The cored sediments have higher Fe, Ti, Cr, Cs, Li, Ni, and V but lower Ca, Na, Mn, Hf, Nb, Sr, Ta, U and Zr contents when compared with the upper continental crust（UCC, Taylor and McLennan, 1985）. The Eu/Eu＊ ratios of the sediments averaging 0.69 indicate that the recycling effect on the Eu anomaly may be minor and the contribution of mafic source rock was unimportant, which can also be depicted in the La-Th-Sc plot（Cullers, 1994） showing a ＂mixed origin＂ close to the felsic end member. The chemistry of the cored sediment can be explained by a mixing model designed by Ho and Chen（1996） with four end members i.e., greywacke, shale, quartzite and limestone, which are widely distributed in the Cenozoic formations of southern Taiwan with greywacke as the dominant contributor followed by shale.展开更多
The vertical profiles of nonylphenol （NP） and nonylphenol ethoxylates （NPEOs） were investigated in a sediment core from the Beipaiming Channel, North China using high sensitive LC-MS and GC-MS metthods In this cor...The vertical profiles of nonylphenol （NP） and nonylphenol ethoxylates （NPEOs） were investigated in a sediment core from the Beipaiming Channel, North China using high sensitive LC-MS and GC-MS metthods In this core, relatively high concentrations of NP and NPEOs occurred in the surface sediment （≤40 cm）, with the maximum value of NP and NPEOs reaching 3539 and 12735 mg/g, respectively, whereas, no NP or NPEOs were detected in deeper sediments （〉40 cm）. The high concentrations of NP and NPEOs in the surface layers suggested recent inputs in this area. NPEOs with short ethoxy chains （NPnEO, n=0-3） were dominant in the NPEO mixture with percentages from 54% to 78%, which were similar to the distribution of homolog NPEO in effluents from nearby sewage treatment plants （STPs）, indicating that the channel received the effluents from these STPs. The sewage treatment ratio was quite similar to that found in North America before the 1980s. Finally, the concentrations of NP and NPEOs were related to the total organic carbon （TOC） （p〈0.001）, suggesting that TOC was an important factor for vertical distribution of NPEOs and NP from the Beipaiming Channel.展开更多
Receptor models are a useful tool for identifying sources of polycyclic aromatic hydrocarbons(PAHs)in multiple environmental media.In this study,three different receptor models(including the principal component analys...Receptor models are a useful tool for identifying sources of polycyclic aromatic hydrocarbons(PAHs)in multiple environmental media.In this study,three different receptor models(including the principal component analysis-multiple linear regression(PCA-MLR),positive matrix factorization(PMF),and Unmix models)were used to apportion the sources of 16 priority PAHs in a sediment core of Lake Dagze Co.TheΣPAHs(sum of all 16 measured PAHs)concentrations ranged from 51.89 to 132.82 ng/g with an average of 80.39 ng/g.TheΣPAHs were dominated by 2-3 ring PAHs,accounting for 80.12%on average,thereby indicating that they mainly originated from biomass and coal combustion and/or from long-range atmospheric transportation.The three models produced consistent source apportionment results.The greatest contributor toΣPAHs was biomass combustion,followed by coal combustion,vehicle emissions,and petrogenic sources.Moreover,the temporal variation of the common sources was well-correlated among models.The multi-method comparison and evaluation results showed that all three models were useful tools for source apportionment of PAHs,with the PMF model providing better results than the PCA-MLR and Unmix models.The temporal trends of factor contributions were verified by PAHs with different ring numbers.Significant correlations were found between the simulated concentrations of each source factor and the PAHs with different ring numbers(P<0.01),except for the petrogenic source identified by the Unmix model(P>0.05).This study can provide useful information for further investigation of source apportionment of PAHs in the sediment cores.展开更多
Inter-dune lake sediment cores are ideal and unavailable materials for study climate and environmental changes of arid region.The precious dating of lake sediment cores is required for carrying out high resolution cli...Inter-dune lake sediment cores are ideal and unavailable materials for study climate and environmental changes of arid region.The precious dating of lake sediment cores is required for carrying out high resolution climate and environmental changes with these cores.The Badain Jaran inter-dune lake group embedding in the sand sea is the展开更多
Understanding global carbon cycle is critical to uncover the mechanisms of global warming and remediate its adverse ef fects on human activities.Organic carbon in marine sediments is an indispensable part of the globa...Understanding global carbon cycle is critical to uncover the mechanisms of global warming and remediate its adverse ef fects on human activities.Organic carbon in marine sediments is an indispensable part of the global carbon reservoir in global carbon cycling.Evaluating such a reservoir calls for quantitative studies of marine carbon burial,which closely depend on quantifying total organic carbon and black carbon in marine sediment cores and subsequently on obtaining their high-resolution temporal sequences.However,the conventional methods for detecting the contents of total organic carbon or black carbon cannot resolve the following specific difficulties,i.e.,(1)a very limited amount of each subsample versus the diverse analytical items,(2) a low and fluctuating recovery rate of total organic carbon or black carbon versus the reproducibility of carbon data,and(3)a large number of subsamples versus the rapid batch measurements.In this work,(i)adopting the customized disposable ceramic crucibles with the microporecontrolled ability,(ii)developing self-made or customized facilities for the procedures of acidification and chemothermal oxidization,and(iii)optimizing procedures and carbon-sulfur analyzer,we have built a novel Wang-Xu-Yuan method(the WXY method)for measuring the contents of total organic carbon or black carbon in marine sediment cores,which includes the procedures of pretreatment,weighing,acidification,chemothermal oxidation and quantification;and can fully meet the requirements of establishing their highresolution temporal sequences,whatever in the recovery,experimental efficiency,accuracy and reliability of the measurements,and homogeneity of samples.In particular,the usage of disposable ceramic crucibles leads to evidently simplify the experimental scenario,which further results in the very high recovery rates for total organic carbon and black carbon.This new technique may provide a significant support for revealing the mechanism of carbon burial and evaluating the capacity of marine carbon accumulation and sequestration.展开更多
The distribution of metals (Cd, Cr, Pb, Cu, Ni and Zn) was determined in sediment cores collected from five major areas representing different anthropogenic activities along the Jordanian coast during 27 February-11 M...The distribution of metals (Cd, Cr, Pb, Cu, Ni and Zn) was determined in sediment cores collected from five major areas representing different anthropogenic activities along the Jordanian coast during 27 February-11 March 2008. Metal concentrations in these sediments were relatively low compared to reported values from polluted areas. At some of the sites metal concentrations showed fluctuations with depth in the core suggesting changes in metal loading with time. The calculated contamination factors (CFs) for the suite of metals decreased in the following order Cd > Pb > Cr > Ni >Zn > Cu. The Pollution Loading Index (PLI) calculated for the different areas were highest at Phosphate Loading Berth (0.008, 0.2607, 0.0161, 0.007, 47.9375 and 0.0296 for Cu, Pb, Ni, Zn, Cd and Cr, respectively) and lowest at Hotel Area (0.0001, 0.0075, 0.0008, 0.0006, 1.0483 and 0.0005 for Cu, Pb, Ni, Zn, Cd and Cr, respectively) with others sites between these extremes. Result of this study could be used to assess the magnitude of pollution at each site and guide rational management decisions. Moreover, the data constitutes a baseline against which future anthropogenic effects can be assessed.展开更多
The occurrence percentage and abundance of General Aerobic Hetero- trophic Bacteria （GAB） were determined by using the method of MPN for 182 sub- samples from 10 sediment cores taken from the Canadian basin and the ...The occurrence percentage and abundance of General Aerobic Hetero- trophic Bacteria （GAB） were determined by using the method of MPN for 182 sub- samples from 10 sediment cores taken from the Canadian basin and the Chukchi Sea at two different culturing temperatures. The results showed that the general occurrence percentage of GAB was quite high, average abundanees of GAB at cultured temperatares of 4℃ and 25℃ were 4.46 ×10^7 and 5.47×10^7 cells·g^-1（wt）, respectively. The highest abundance of GAB occurred at 20 -22 cm section in the sediment. GAB abundances changed among the section of sediments, but there is a trend ： the a-bundances at the middle or lower sections were lower than those at upper section. Cultivation at 25℃ could improve the occurrence percentage and abundances of GAB, which suggests that the increasing of temperature may change the living circum-stances of GAB. The differences of GAB among the latitudes areas indicated that occurrence percentage and abundances of GAB in middle latitude areas were higher than those in the higher or lower latitude areas, and were more obvious at 4℃ than those at 25℃. The GAB abundances in sediment under the shallower water seemed to be low- er than those in sediments under the deeper water and this status was more obvious at 25℃ than that at 4℃.展开更多
Two depositional processes controlled the muddy sediments in the South China Sea Basin. Bathyal sediments depositional rate was 7.66 cm/la in the northern continental slope of the Basin where turbidity current was alm...Two depositional processes controlled the muddy sediments in the South China Sea Basin. Bathyal sediments depositional rate was 7.66 cm/la in the northern continental slope of the Basin where turbidity current was almost nonexistent. In the northern margin of the Basin, abyssal sediment depositional rate was 5.05cm/ka and turbidity current occurrence averaged 0.22 per 1000 years. Turbidite was found in the middle of the Basin. Over half of the muddy sediments in the deep sea basin were deposited by turbidity currents, and had typically graded bedding, and contents of organic matter, calcareous material and micropaleontologic species inconsistent with the environment.展开更多
The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a ran...The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a range of studies. However, in consideration of the operability and available sample length in collecting hard sediments, these methods exhibit no advantages. In this paper, a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coting is presented. The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity. During sampling process, the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode. The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle. Besides, its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.展开更多
The results of 210 Pb measurements in the lake sediment core from Antarctica are reported: the relative specific activities of 210 Pb in the lake sediment were found to decrease exponentially with ...The results of 210 Pb measurements in the lake sediment core from Antarctica are reported: the relative specific activities of 210 Pb in the lake sediment were found to decrease exponentially with the depth in the study area; the sedimentation rate of the lake is about 0.072 cm/a. This paper shows that 210 Pb method is applicable to Antarctic lake sediment ,and during the 1960's the atmospheric nuclear tests have an effect on the rate of 210 Pb deposition in Antarctica.展开更多
Anisotropy of magnetic susceptibility (AMS) is a well-developed technique increaseingly used in petro-fabric determination. ItS application to two Mackereth cores JX91-2A and JX91-2B, taken from thesame site in the ce...Anisotropy of magnetic susceptibility (AMS) is a well-developed technique increaseingly used in petro-fabric determination. ItS application to two Mackereth cores JX91-2A and JX91-2B, taken from thesame site in the central Bohai Sea, revealed 3D magnetic fabrics of the sediments as expressed with susce-ptibility ellipsoids. The flat seafloor and the relatively quiet depositional environment in the semi-isolatedBohai Sea should asult in a primary fabric with horisontally obate susocptibility el1ipsoids. Mormwr,the inaxing downcore totaI anisotropy comprising mainly of magntic foliation nsulting fIrom sedimentcompaction should also lead to flat ellipsoids. Therefore, the off-pole meam dindions of minimurn axes ofaseptibility ellipsoids on stermnets must indicate that the two coas are ti]ted re1ative to the flat anfloor.Use of Fisher statisties showh the tilt angles to be 14° for JX91-2A and 23°for JX91 -2B from whichthe tna depths of the coas were dedded accordingly.展开更多
Ten stenols and stanols were identified by TLC , GC and GC-MS-DS in a marine sediment core from Beibu Bay , the South China Sea .C27, C28 and C29 A5 stenols and 5a- stanols mainly come from zoopiankton, algae and phyt...Ten stenols and stanols were identified by TLC , GC and GC-MS-DS in a marine sediment core from Beibu Bay , the South China Sea .C27, C28 and C29 A5 stenols and 5a- stanols mainly come from zoopiankton, algae and phytoplankton in marine environment. C29 24-ethylcholest- 5 - en- 3B- ol is thought to indicate input of terrigenous organic matter . The increase of C27 . C28 and C29 5a-stanol /5 stenol ratios with sediment depth shows the evolution of stenols and stanols in the marine sediment core .展开更多
基金Supported by Science and Technology Project from Jiangxi Provincial Department of Education(GJJ09430)International Scienceand Technology Cooperation Project(2006DFB91920)NationalKey Water Project(2008ZX07526-008)~~
文摘The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg/g with the change of depth,which was divided into three distribution types as follows:TN content decreases gradually with the increase of depth,TN content increases gradually with the increase of depth or higher content in the middle but lower content in two ends.NH4+-N content ranged from 8.7 ...
基金This study was supported by the National Science Foundation for Outstanding Young Scientists of China under contract No. 49925614 the Knowledge Innovation Program of the Chinese Academy of Sciences under contract No. KZCX1 - SW -01-08.
文摘Study on form characteristics of nitrogen in marine sediments is the primary method to research its biogeochemical cycling and nitrogen form characteristics in core sediments can reflect the process and results of early diagenesis in a certain degree. In this paper, Sequential extraction process in natural grain size was used for studying the existent forms of nitrogen in five core sediments of the southern Bohai Sea for the first time. Nitrogen was divided into two parts - transferable and fixed based on whether it could be extracted by the reagent. Distributions and early diagenesis of transferable nitrogen forms in the southern Bohai Sea were researched integratedly. Results indicate that IEF - N and OSF-N are predominant forms in transferable part in the studied core sediments. Contents of different nitrogen forms vary differently with depth, and have different diagenesis process. Decomposition constant of organic nitrogen (ON) and OC are about 15.51 -× 10^(-3)a^(-3)and 4.79× 10^(-3)a^(-1) respectively, and the decomposition content of biogenic elements C, N, P, Si has the sequence N>P>CSi. OC/TN (simplified as C/N in the following) ratio is much lower than OC/ON, which indicates that sediment preserves plenty of inorganic nitrogen (IN) and/or fixed nitrogen, and the decrease of OC/ON ratio with depth is due to ON reservation in sediments. Generally, transferable nitrogen accounts for more proportion of TN in the surface layer than in the deep layer of core sediments, whereas, some stable forms of nitrogen can activate and become transferable under appropriate environment, which induces the proportion of transferable nitrogen in TN in the deep layer to be almost the same as that in the surface layer.
基金The National Natural Science Foundation of China under contract No.40606025the Program for New Century Excellent Talents in University,Ministry of Education under contract No.NCET-06-0446the "908" Program of State Oceanic Administration under contract No.908-ZC-II-03
文摘The concentration of zinc, chromium, cadmium, nickel, lead and copper was measured on both surface sediments and core sediments in the Shenzhen Bay. The average contents of all metals have exceeded the background values in the coastal zone of Guangdong Province. Cadmium is a heavy pollution matter which indicates a strong pollution level according to the ecological risk coefficient method. The ecological risk index of the whole area is 299 which belongs to middle and strong level. The area with strong pollution level is the near shore area closing to the inside of Shenzhen Bay, Shakou area is in the middle level while the weak pollution level occurs in Shenzhenhe Estuary according to ecological risk index. The four sediment cores can be divided into two parts based on lead-210 dating, sediments size analysis and economic development period in surrounding areas since 1950 with strong human intervention. The sediment size, deposition rate and human activities have positive relationship with the contents of heavy metals which directly impact the pollution level of heavy metals in sediments in Shenzhen Bay.
文摘Sequential core sediments from northwestern Taihu Lake in China were analyzed for grain size, organic carbon and heavy metal content. The sediments are composed of organic-poor clayey-fine silts. The chemical speciations of Cu, Fe, Mn, Ni, Pb, and Zn were also analyzed using the BCR sequential extraction procedure. Cu, Fe, Ni, and Zn are mainly associated with the residue fraction; Mn is concentrated mainly in exchangeable/carbonate fraction and residue fraction; and Pb mainly in Fe/Mn oxide fraction and organic/sulfide fraction. The exchangeable/carbonate fractions of Cu, Fe, Ni, Zn and Pb are lower. The fractions of Ni, Pb and Zn bound to the Fe/Mn oxide have significant correlations with reducible Mn; the organic/sulfide fractions of Cu, Mn, Ni, Pb, and Zn have significant correlations with TOC. The extractable fractions of Cu, Mn, Ni, Pb, and Zn are high at the top 4 cm of the core sediments as compared to those in the deeper layers, showing the anthropogenic input of heavy metals is due to rapid industrial development. The heavy metal pollution history of the sediments has been recorded since the late 1970s, determined by the result of {{}+{137}Cs} dating.
基金supported by the Doctoral Research Initiation Fund Project of Hebei Normal University(No.L2025B19)PhD Fellowship of the State Key Laboratory of Marine Environmental Science at Xiamen University.
文摘Protoporphyrin Ⅸ(PPⅨ), a basic porphyrin system found in nature, all “porphyrin-type”tetrapyrroles with a biological function are biosynthetically derived thereof. PPⅨ is a metalloprosthetic group of numerous proteins involved in diverse metabolic and respiratory processes across all domains of life, and is thus considered essential for respiring organisms. Determining the biotic and abiotic factors that influence marine microbial growth and community structure is critical for understanding global biogeochemical cycles. Here,we present vertical profiles of intracellular PPⅨ and four derivative products(Chlorophylla/b and Pheophytin-a/b) from two coastal sediment cores, alongside ancillary geochemical and 16S rRNA microbial community data. Our findings indicated that PPⅨ is present in the natural sediment environment and displays a decreasing trend with depth, revealing a significant positive correlation with both organic matter and microbial abundance. Cooccurrence networks revealed that the environmental distribution of PPⅨ was positively correlated with the microbial porphyrin producer(high genetic completeness), but negatively correlated with auxotrophs(absence or low genetic completeness). It emphasized the critical role of PPⅨ as a biological molecule involved in key physiological processes. These results suggest that PPⅨ is a prominent component of the shared extracellular metabolite pool, especially in anoxic marine sediments where it exists at physiologically relevant concentrations for microbial metabolism. This study highlighted the significance of PPⅨ in microbial ecology and its potential impact on biogeochemical cycles in marine sedimentary environments.
基金Project(1212010) supported by the China Geological Survey for Ecosystem Geochemistry Assessment in City of Changsha,Zhuzhou and Xiangtan
文摘Samples were collected from two core sediments(C1 and C2) of Xiangjiang River,Chang-Zhu-Tan region,Hunan Province,China.The heavy metal contents are relatively higher,especially for the surface or near the surface layers.The calculated anthropogenic factor values indicate that all the heavy metals except for Cr in the core samples are enriched,especially for Cd,with the maximum enriching coefficients of 119.44,and 84.67 in C1 and C2,respectively.The correlation of heavy metals with sulphur indicates that they are precipitated as metal sulphides.Correlation matrix shows significant association between heavy metals and mud.Factor analysis identifies that signified anthropogenic activities affect the region of Xiangjiang River.
文摘The western Bay of Bengal is particularly susceptible to the harmful impacts of increasing coastal pollution,as coastal population and urban development are occurring at unprecedented rates.The rapid urbanization and industrialization along the east coast of India coupled with the transfer of contaminants into the Bay of Bengal through riverine systems,causing a direct impact on marine ecosystems.In the present study,an attempt has been made to understand the heavy metal distribution on shelf sediments in the western part of the Bay of Bengal to infer their source,processes,and historical changes in marine pollution.Three short sediment core samples were collected and analysed for sediment texture,organic matter,and heavy metals.Cores 1 and 2 contain a high amount of sand content,representing shallow marine with moderate to high-energy conditions,and were deposited at a recent time.Core 3 was dominated by muddy sand to sandy mud,which denotes calm sedimentation without any turbulence,and these sediments were deposited under relatively low-energy conditions.The higher concentration of organic matter in the top layers of the core indicates both marine and terrestrial input.The heavy metal contents show quite heterogeneous and variable distributions from one element to another and from one core to another.The calculated pollution indices such as Contamination Factor(CF),and Geoaccumulation Index(Igeo)and Pollution Load Index(PLI)values indicate that all the core sub-samples are severely enriched and highly polluted by Cd and moderately polluted by Pb.The increased heavy metal concentration in the upper portion of the sediment cores and moderate to considerable ecological risks indicate that these metals have been deposited in the study area for the past few decades.
基金The National Basic Research Program (973) of China (No. 2002CB412409) and the Hi-Tech Research and Development Program(863) of China(No. 2002AA648010)
文摘Three sediment cores were collected in November 2003 from Dagu estuary to Qikou estuary. The main polluted heavy metals in the sediment of tidal zones for the Bohai Bay have been found by analyzing the relationship among the contents of heavy metals, the contents of geochemical elements （Fe, AI and Mn） and the size of grain. The dominating contaminative elements in tidal sediments of Bohai Bay are Pb, Zn and Cd. Their contents are higher than the corresponding upper limit of environmental background values and they have very faint correlation with the corresponding contents of geochemical elements and the size of grain, indicating the anthropogenic enrichment. Especially, the preliminary study on the pollution sources and the history of heavy metals in the Dagu estuary has been done using the dated results. The contamination by Zn and Cd also started in the middle 1950s, while the contamination by Pb appeared in the early 1940s. The pollution by Zn and Cd mainly originate from sewage discharge, while the pollution by Pb has many sources, like atmosphere deposition and industrial discharRe.
基金supported by the Central Geological Survey of the Ministry of Economic Affairs under grant 5226902000-05-94-02, No. NRF-2012R1A1A2005044 and 5226902000-95-02
文摘The cored sediments sampled by R/V Marion Dufrense in the active margin off southwestern Taiwan on the east side of the Manila Trench are mostly muds consisting mainly of quartz, feldspar, illite, chlorite ＋ kaolinite with a trace amount of montmorillonite. The cored sediments have higher Fe, Ti, Cr, Cs, Li, Ni, and V but lower Ca, Na, Mn, Hf, Nb, Sr, Ta, U and Zr contents when compared with the upper continental crust（UCC, Taylor and McLennan, 1985）. The Eu/Eu＊ ratios of the sediments averaging 0.69 indicate that the recycling effect on the Eu anomaly may be minor and the contribution of mafic source rock was unimportant, which can also be depicted in the La-Th-Sc plot（Cullers, 1994） showing a ＂mixed origin＂ close to the felsic end member. The chemistry of the cored sediment can be explained by a mixing model designed by Ho and Chen（1996） with four end members i.e., greywacke, shale, quartzite and limestone, which are widely distributed in the Cenozoic formations of southern Taiwan with greywacke as the dominant contributor followed by shale.
基金Project supported by the National Basic Research Program of China (No. 2007CB407304, 2003CB415004)the National Natural Science Foundation of China (No. 20307010)
文摘The vertical profiles of nonylphenol （NP） and nonylphenol ethoxylates （NPEOs） were investigated in a sediment core from the Beipaiming Channel, North China using high sensitive LC-MS and GC-MS metthods In this core, relatively high concentrations of NP and NPEOs occurred in the surface sediment （≤40 cm）, with the maximum value of NP and NPEOs reaching 3539 and 12735 mg/g, respectively, whereas, no NP or NPEOs were detected in deeper sediments （〉40 cm）. The high concentrations of NP and NPEOs in the surface layers suggested recent inputs in this area. NPEOs with short ethoxy chains （NPnEO, n=0-3） were dominant in the NPEO mixture with percentages from 54% to 78%, which were similar to the distribution of homolog NPEO in effluents from nearby sewage treatment plants （STPs）, indicating that the channel received the effluents from these STPs. The sewage treatment ratio was quite similar to that found in North America before the 1980s. Finally, the concentrations of NP and NPEOs were related to the total organic carbon （TOC） （p〈0.001）, suggesting that TOC was an important factor for vertical distribution of NPEOs and NP from the Beipaiming Channel.
基金supported by the National Natural Science Foundation of China(Nos.41773097,41971286)the Postgraduate Research Innovation project of Jiangsu Province(No.KYCX21_1330)。
文摘Receptor models are a useful tool for identifying sources of polycyclic aromatic hydrocarbons(PAHs)in multiple environmental media.In this study,three different receptor models(including the principal component analysis-multiple linear regression(PCA-MLR),positive matrix factorization(PMF),and Unmix models)were used to apportion the sources of 16 priority PAHs in a sediment core of Lake Dagze Co.TheΣPAHs(sum of all 16 measured PAHs)concentrations ranged from 51.89 to 132.82 ng/g with an average of 80.39 ng/g.TheΣPAHs were dominated by 2-3 ring PAHs,accounting for 80.12%on average,thereby indicating that they mainly originated from biomass and coal combustion and/or from long-range atmospheric transportation.The three models produced consistent source apportionment results.The greatest contributor toΣPAHs was biomass combustion,followed by coal combustion,vehicle emissions,and petrogenic sources.Moreover,the temporal variation of the common sources was well-correlated among models.The multi-method comparison and evaluation results showed that all three models were useful tools for source apportionment of PAHs,with the PMF model providing better results than the PCA-MLR and Unmix models.The temporal trends of factor contributions were verified by PAHs with different ring numbers.Significant correlations were found between the simulated concentrations of each source factor and the PAHs with different ring numbers(P<0.01),except for the petrogenic source identified by the Unmix model(P>0.05).This study can provide useful information for further investigation of source apportionment of PAHs in the sediment cores.
文摘Inter-dune lake sediment cores are ideal and unavailable materials for study climate and environmental changes of arid region.The precious dating of lake sediment cores is required for carrying out high resolution climate and environmental changes with these cores.The Badain Jaran inter-dune lake group embedding in the sand sea is the
基金Supported by the National Basic Research Program of China(973 Program)(No.2012CB956004)the Fundamental Research Funds for the Central Universities(No.16lgjc22)
文摘Understanding global carbon cycle is critical to uncover the mechanisms of global warming and remediate its adverse ef fects on human activities.Organic carbon in marine sediments is an indispensable part of the global carbon reservoir in global carbon cycling.Evaluating such a reservoir calls for quantitative studies of marine carbon burial,which closely depend on quantifying total organic carbon and black carbon in marine sediment cores and subsequently on obtaining their high-resolution temporal sequences.However,the conventional methods for detecting the contents of total organic carbon or black carbon cannot resolve the following specific difficulties,i.e.,(1)a very limited amount of each subsample versus the diverse analytical items,(2) a low and fluctuating recovery rate of total organic carbon or black carbon versus the reproducibility of carbon data,and(3)a large number of subsamples versus the rapid batch measurements.In this work,(i)adopting the customized disposable ceramic crucibles with the microporecontrolled ability,(ii)developing self-made or customized facilities for the procedures of acidification and chemothermal oxidization,and(iii)optimizing procedures and carbon-sulfur analyzer,we have built a novel Wang-Xu-Yuan method(the WXY method)for measuring the contents of total organic carbon or black carbon in marine sediment cores,which includes the procedures of pretreatment,weighing,acidification,chemothermal oxidation and quantification;and can fully meet the requirements of establishing their highresolution temporal sequences,whatever in the recovery,experimental efficiency,accuracy and reliability of the measurements,and homogeneity of samples.In particular,the usage of disposable ceramic crucibles leads to evidently simplify the experimental scenario,which further results in the very high recovery rates for total organic carbon and black carbon.This new technique may provide a significant support for revealing the mechanism of carbon burial and evaluating the capacity of marine carbon accumulation and sequestration.
文摘The distribution of metals (Cd, Cr, Pb, Cu, Ni and Zn) was determined in sediment cores collected from five major areas representing different anthropogenic activities along the Jordanian coast during 27 February-11 March 2008. Metal concentrations in these sediments were relatively low compared to reported values from polluted areas. At some of the sites metal concentrations showed fluctuations with depth in the core suggesting changes in metal loading with time. The calculated contamination factors (CFs) for the suite of metals decreased in the following order Cd > Pb > Cr > Ni >Zn > Cu. The Pollution Loading Index (PLI) calculated for the different areas were highest at Phosphate Loading Berth (0.008, 0.2607, 0.0161, 0.007, 47.9375 and 0.0296 for Cu, Pb, Ni, Zn, Cd and Cr, respectively) and lowest at Hotel Area (0.0001, 0.0075, 0.0008, 0.0006, 1.0483 and 0.0005 for Cu, Pb, Ni, Zn, Cd and Cr, respectively) with others sites between these extremes. Result of this study could be used to assess the magnitude of pollution at each site and guide rational management decisions. Moreover, the data constitutes a baseline against which future anthropogenic effects can be assessed.
基金sponsored by the national ministry of finance.And as a part of the second Arctic research expedition(CHINARE-2003) which is organized by Polar Expedition Office of State Oceanic Administration of China,we would like to thank the crew on RV Xuelong for their support and assistance.Research funds are supplied by National Natural Science Foundation of China(No.40576060,40376017 and 40176017).
文摘The occurrence percentage and abundance of General Aerobic Hetero- trophic Bacteria （GAB） were determined by using the method of MPN for 182 sub- samples from 10 sediment cores taken from the Canadian basin and the Chukchi Sea at two different culturing temperatures. The results showed that the general occurrence percentage of GAB was quite high, average abundanees of GAB at cultured temperatares of 4℃ and 25℃ were 4.46 ×10^7 and 5.47×10^7 cells·g^-1（wt）, respectively. The highest abundance of GAB occurred at 20 -22 cm section in the sediment. GAB abundances changed among the section of sediments, but there is a trend ： the a-bundances at the middle or lower sections were lower than those at upper section. Cultivation at 25℃ could improve the occurrence percentage and abundances of GAB, which suggests that the increasing of temperature may change the living circum-stances of GAB. The differences of GAB among the latitudes areas indicated that occurrence percentage and abundances of GAB in middle latitude areas were higher than those in the higher or lower latitude areas, and were more obvious at 4℃ than those at 25℃. The GAB abundances in sediment under the shallower water seemed to be low- er than those in sediments under the deeper water and this status was more obvious at 25℃ than that at 4℃.
文摘Two depositional processes controlled the muddy sediments in the South China Sea Basin. Bathyal sediments depositional rate was 7.66 cm/la in the northern continental slope of the Basin where turbidity current was almost nonexistent. In the northern margin of the Basin, abyssal sediment depositional rate was 5.05cm/ka and turbidity current occurrence averaged 0.22 per 1000 years. Turbidite was found in the middle of the Basin. Over half of the muddy sediments in the deep sea basin were deposited by turbidity currents, and had typically graded bedding, and contents of organic matter, calcareous material and micropaleontologic species inconsistent with the environment.
基金supported by the National Natural Science Foundation of China (Grant No. 40806043)
文摘The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a range of studies. However, in consideration of the operability and available sample length in collecting hard sediments, these methods exhibit no advantages. In this paper, a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coting is presented. The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity. During sampling process, the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode. The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle. Besides, its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.
文摘The results of 210 Pb measurements in the lake sediment core from Antarctica are reported: the relative specific activities of 210 Pb in the lake sediment were found to decrease exponentially with the depth in the study area; the sedimentation rate of the lake is about 0.072 cm/a. This paper shows that 210 Pb method is applicable to Antarctic lake sediment ,and during the 1960's the atmospheric nuclear tests have an effect on the rate of 210 Pb deposition in Antarctica.
基金The project was suppoted by National Natural Science Foundation of China(No.49070189)and the Bntish Council(ALCS SCEHEME-PEK/992/108)
文摘Anisotropy of magnetic susceptibility (AMS) is a well-developed technique increaseingly used in petro-fabric determination. ItS application to two Mackereth cores JX91-2A and JX91-2B, taken from thesame site in the central Bohai Sea, revealed 3D magnetic fabrics of the sediments as expressed with susce-ptibility ellipsoids. The flat seafloor and the relatively quiet depositional environment in the semi-isolatedBohai Sea should asult in a primary fabric with horisontally obate susocptibility el1ipsoids. Mormwr,the inaxing downcore totaI anisotropy comprising mainly of magntic foliation nsulting fIrom sedimentcompaction should also lead to flat ellipsoids. Therefore, the off-pole meam dindions of minimurn axes ofaseptibility ellipsoids on stermnets must indicate that the two coas are ti]ted re1ative to the flat anfloor.Use of Fisher statisties showh the tilt angles to be 14° for JX91-2A and 23°for JX91 -2B from whichthe tna depths of the coas were dedded accordingly.
基金The project was supported by the National Natural Science Foundation of China (48970111)
文摘Ten stenols and stanols were identified by TLC , GC and GC-MS-DS in a marine sediment core from Beibu Bay , the South China Sea .C27, C28 and C29 A5 stenols and 5a- stanols mainly come from zoopiankton, algae and phytoplankton in marine environment. C29 24-ethylcholest- 5 - en- 3B- ol is thought to indicate input of terrigenous organic matter . The increase of C27 . C28 and C29 5a-stanol /5 stenol ratios with sediment depth shows the evolution of stenols and stanols in the marine sediment core .
