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1.
????GM(1,1)???????????????????о????????????????x(1)(1)??x(1)(n)??????????GM(1,1)??????????????????x(1)(1)??x(1)(n)?GM(1,1)????????????·???????x(1)(t)?????????????????1-AGO???е???????????С?????????????????????????????????????????????????????????????????з?????????????????????????????÷?Χ?????????????????????????????????????GM(1,1)????????????????????GM(1,1)????  相似文献   

2.
Lead(Pb) and its compounds are common pollutants in industrial wastewaters.To develop appropriate Pb 2+ treatment technologies,aerobic granules(AG) and bacterial alginates(BA) were studied as alternative biosorbents to remove Pb 2+ from aqueous solutions.The biosorption mechanism of AG and BA were further analyzed to determine which functional groups in AG and BA are active in Pb 2+ biosorption.In this paper,the Pb 2+ biosorption behavior of AG and BA was respectively investigated in batch experiments from the perspectives of the initial pH,contact time,and initial Pb 2+ concentration.The results showed that biosorption of Pb 2+ by AG and BA occurred within 60min at the initial Pb 2+ concentrations(0 150 mg L-1).The actual saturated Pb 2+ biosorption capability of AG was 101.97 mg g-1(dry weight of aerobic granular biomass).When the initial pH was 5,the biosorption capability of AG and BA was highest at the initial Pb 2+ concentrations(0 20mg L-1).During the process of Pb 2+ biosorption,K +,Ca 2+,and Mg 2+ were released.The Ion Chromatography(IC) and Fourier Transform Infrared Spectroscopy(FTIR) further highlighted the main role of ion exchange between Ca 2+ and Pb 2+ and sequestration of Pb 2+ with carboxyl(-COO) of AG and BA.This analogical analysis verifies that BA is responsible for biosorption of Pb 2+ by AG.At the same optimal pH,AG cultivated with different carbon source has different Pb 2+ biosorption capacity.The Pb 2+ biosorption by AG with sodium acetate as the sole carbon source is higher than AG with glucose as carbon source.  相似文献   

3.
Surface sediments and bivalves were collected from the Changjiang Estuary in December 2003 and November 2004, respectively. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in these samples were measured with high-resolution chromatography (HRGC)/High Resolution Mass Spectrometer (HRMS). The concentrations of total PCDD/Fs and toxic equivalent (TEQ) were 169.83±119.63 and 0.81±0.36 pg/g dry weight (dw) in sediments, and 580.33±240.17 and 7.24±3.65 pg/g dw in bivalves. The homolog compositions of PCDD/Fs were similar among samples, the most abundant congener was octa-chlorinated dibenzo-p-dioxin (OCDD) and then octa-chlorinated dibenzofuran (OCDF) and 1,2,3,4,6,7,8-hepta-chlorinated dibenzo-p-dioxin (HpCDD). The herbicide pentachlorophenol (PCP) and sodium pentachlorophenol (Na-PCP) were proved the main source of PCDD/Fs in this area.  相似文献   

4.
This study aims to assess conservation practices in Izta-Popo National Park(Central Mexico) by evaluating the mechanisms of sediment transfer. We applied a methodology based on fallout ~(137)Cs and optically stimulated luminescence(OSL) analysis. This was tested in the upper catchment of Amalacaxco Gorge, selected for being one of the sectors of the park in which man-made actions have been implemented in last decades to favor forest growth in the alpine grassland and to reduce the effect of water runoff. We quantified the ~(137)Cs activity using gamma and beta spectrometry of fine sediment grains extracted from the surface of parcels of 0.4 m2 in areas of natural forest, natural alpine grassland, alpine grassland with conservation practices, ravines and trails. In general, ~(137)Cs values increases as local slope decreases as it was expected. The natural forest is the most stable area in terms of soil erosion and sediment accumulation and, mean ~(137)Cs activity was taken as reference to assess cumulative zones, with higher ~(137)Cs values and erosive, with lower. We found that trails are accumulative surfaces but in other areas, erosion predominates. Man-made ditches, trenches and afforestation in the alpine grassland have higher ~(137)Cs values than thenatural grassland, which indicates that conservation practices are limiting the sediment transfer from hillslopes to channels, however, soil retention is less than in the natural grassland. Additionally, we evaluated the luminescence(OSL) values obtained from samples extracted from the sediment transported in ravines that are cutting into different sectors of the study area to assess the grade of resetting of fluvial materials. These luminescence results indicated that the sediment transported in ravines that are cutting into the natural forest and alpine grassland is bleached more efficiently than the sediment transported in the alpine grassland with conservation practices. Results of fallout ~(137)Cs and luminescence strongly suggest that man-made actions in this part of the Izta-Popo National Park are dramatically modifying the natural mechanisms of sediment transfer and favoring soil erosion. We conclude that made ditches, trenches and afforestation are not an effective conservation practice in Amalacaxco Gorge because they are promoting soil erosion instead of reducing it.  相似文献   

5.
This study was conducted to compare lipid and fatty acid composition of cod,haddock and halibut.Three groups of cod(276 g±61 g),haddock(538 g±83 g)and halibut(3704 g±221 g)were maintained with commercial feeds mainly based on fish meal and marine fish oil for 12 weeks prior to sampling.The fatty acid compositions of muscle and liver were determined by GC/FID after derivatization of extracted lipids into fatty acid methyl esters(FAME).Lipids were also fractionated into neutral and polar lipids using Waters silica Sep-Pak(R).The phospholipid fraction was further separated by high-performance thin-layer chromatography(HPTLC)and the FAME profile was obtained.Results of the present study showed that cod and haddock were lean fish and their total muscle lipid contents were 0.8% and 0.7%,respectively,with phospholipid constituting 83.6% and 87.5% of the total muscle lipid,respectively.Halibut was a medium-fat fish and its muscle lipid content was 8%,with 84% of the total muscle lipid being neutral lipid.Total liver lipid contents of cod,haddock and halibut were 36.9%,67.2% and 30.7%,respectively,of which the neutral lipids accounted for the major fraction(88.1%-97.1%).Polyunsaturated fatty acids were the most abundant in cod and haddock muscle neutral lipid.Monounsaturated fatty acid level was the highest in halibut muscle neutral lipid.Fatty acid compositions of phospholipid were relatively constant.In summary,the liver of cod and haddock as lean fish was the main lipid reserve organ,and structural phospholipid is the major lipid form in flesh.However,as a medium-fat fish,halibut stored lipid in both their liver and muscle.  相似文献   

6.
Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO), on the temporal variations of the annual water discharge at the Lijin station in the Huanghe (Yellow) River and at the Datong station in the Changjiang (Yangtze) River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis (EMD- MESA) method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.  相似文献   

7.
8.
Allelic variation in a total of 7 microsatellites was examined between elvers of freshwater eels (Anguillajaponica and Anguilla anguilla). The number of alleles at these loci ranged from 8 to 26. A single test of each locus revealed significant deficits of heterozygotes (P〈0.01). Significant departure from expectations of Hardy-Weinberg equilibrium (HWE) was found for all loci within four subpopulations of A. japonica, which opposes the panmixia hypothesis of Schmidt. Also exact tests of population differentiation based on allelic frequency distribution disagree the hypothesis of random distribution of individuals among populations. Population structure among four populations of A. japonica was revealed with FST value of 0.009 8 (P=-0.000 48; 10 000 iteration). Pairwise matrixes of FST and RST showed a significant difference between two distantly related species-A, japonica and A. anguilla. Divergent time of the two species calculated by Goldstein method is over 2 million years. The results may challenge the Schmidt's theory about the distribution of freshwater eels.  相似文献   

9.
企鹅珍珠贝人工养殖及育珠的研究   总被引:1,自引:0,他引:1  
在幼贝中间养成中采用柱形笼养殖法,母贝的养成中采用穿耳开放式养殖法,与全程采用锥形笼的传统式养殖方法相比较,进行企鹅珍珠贝人工养殖。结果表明:采用本技术养殖企鹅珍珠贝,在幼贝中间养成阶段,比传统养殖的壳高生长速率提高32·1%(P<0·05),壳长生长速率提高30·3%(P<0·01),成活率提高36%(P<0·01);母贝养成阶段,比传统养殖的壳高生长速率提高28·1%(P<0·05),壳长生长速率提高26·7%(P<0·01),成活率提高18·3%(P<0·01)。同时进行企鹅珍珠贝人工培育游离珠实验,植核贝在休养期和育珠期存活率分别为71·2%和54·3%,留核率分别为29·6·6%和21·0%,成珠率58·6%,优质珠比例为26·7%。  相似文献   

10.
Heavy metal pollution is one of the most important environmental problems today.Biosorption is an innovative tech-nology that employs biological materials to accumulate heavy metals from waste water through metabolic process or physicochemi-cal pathways of uptake.Even though several physical and chemical methods are available for removal of heavy metals,currently many biological materials such as bacteria,algae,yeasts and fungi have been widely used due to their good performance,low cost and large quantity of availability.The aim of the present study is to explore the biosorption of toxic heavy metals,Cr(VI),Cr(III),Pb(II) and Cd(II) by algal biomass obtained from algae Sargassum wightii(brown) and Caulerpa racemosa(green).Biosorption of algal biomass was found to be biomass concentration-and pH-dependent,while the maximal biosorption was found at pH 5.0 and with the metal concentration of 100 mg L-1.S.wightii showed the maximal metal biosorption at the biomass concentration of 25 g L-1,followed by C.racemosa with the maximal biosorption at 30 g L-1.S.wightii showed 78% biosorption of Cr(VI),Cr(III),Pb(II) and Cd(II) ions.C.racemosa exhibited 85% biosorption of Cd(II) and Cr(VI),and 50% biosorption of Cr(III) and Pb(II).The results of our study suggest that seaweed biomass can be used efficiently for  相似文献   

11.
河南省确山县为“古道国地”。道国虽小,却历虞、夏、商、周数代,并处于“中路”古道之中,具有非常重要的战略地位。研究道国及其有关问题,对于认识中国交通发展史中国经济发展史、以及中国姓氏的发展变化,均有着不可忽视的价值。  相似文献   

12.
An April 1996 to March 1997 comparative study on the abundance and secondary production ofBranchiura sowerbyi Beddard, 1892 in two typical shallow lakes showed that in Houhu, an algae-dominated lake, the worm density (68 ind·m−2) peaked in July, biomass (1.930 g·m−2) peaked in June, while in Biandantang, a macrophyte-dominated lake, standing stock (density: 60 ind·m−2; biomass: 1.019 g·m−2 in wet weight) peaked in December. Secondary production of the animal in Houhu Lake was 3.413 g wet wt m−2 a−1, a little more than that (2.675 g wet wt m−2 a−1) in Biandantang Lake. Their turnover rates (P/B ratios) were 4.0 and 5.0, respectively. Project (39600019 and 39430101) supported by NSFC.  相似文献   

13.
The effects of changing salinity and nitrogen limitation on dimethylsulfoniopropionate(DMSP) and dimethylsulfide(DMS) concentrations were investigated in batch cultures of coastal diatom Skeletonema costatum,an ecologically important species.Changes in salinity from 20-32 caused no measurable variation in cell growth or culture yield,but increased intracellular DMSP per cell by 30%.Nitrogen limitation caused up to a two-fold increase in total DMSP per cell and up to a three-fold increase in DMS per cell.These changes in DMSP and DMS per cell in the Skeletonema costatum cultures with nitrogen limitation and changing salinity were primarily attributed to the physiological functions of DMSP as an osmolyte and an antioxidant.The data obtained in this study indicated that nitrogen limitation and salinity may play an important role in climate feedback mechanisms involving biologically derived DMS.  相似文献   

14.
In the present study, galactosylated chitosan (Gal-CS) was conjugated with methoxy poly(ethylene glycol) (mPEG) as a hydrophilic group. The structure of Gal-CS-mPEG polymer was characterized and the nanoparticles (NPs) were prepared using ironic gelation method. The study was designed to investigate the characteristics and functions of Gal-CS-mPEG NPs. The morphology of Gal-CS-mPEG NPs was observed by SEM and it was a compact and spherical shape. The size of the NPs was approximately 200 nm in diameter under the ideal process parameters. The interaction between Gal-CS-mPEG NPs and pDNA, and the protection of pDNA against DNase I and serum degradation by Gal-CS-mPEG NPs were evaluated. Agarose gel electrophoresis results showed that Gal-CS-mPEG NPs had strong interaction with pDNA at the weight ratio of 12:1, 4:1 and 2:1 and could protect pDNA from DNase I and serum degradation. Gal-CS-mPEG NPs exhibited high loading efficiency and sustainable in vitro release. The blood compatibility studies demonstrated that Gal-CS-mPEG NPs had superior compatibility with erythrocytes in terms of aggregation degree and hemolysis level. Gal-CS-mPEG NPs showed no cytotoxicity on L929 cells, which is a normal mouse connective tissue fibroblast, but showed inhibitory effects on the proliferation of Bel-7402 cells, which is a liver cancer cell line. In conclusion, Gal-CS-mPEG NP is a bio-safe and efficient gene carrier with potential application in gene delivery.  相似文献   

15.
We collected 3 596 Metapenaeopsis stridulans (Decapoda: Penaeidae) from the southeast coast of India between January and December 2007. Sixty three specimens (43 females and 18 males) were parasitized by the bopyrid isopod Epipenaeon ingens (Isopoda: Bopyridae). This is the first report of the occurrence of E. ingens in this host; therefore, it was considered as a new host record. The highest level of infestation (3.2%) occurred in October 2007, coincident with observations of gravid females (9). The total prevalence and presence of gravid females were 17.46% and 28%, respectively. Infestation caused a characteristic bulge of the branchial chamber, growth retardation, and degeneration of the sex organs, but had no effect on the host weight.  相似文献   

16.
17.
将局部均值分解(LMD)方法应用在监测数据中。实验结果表明,LMD-GM(1,1)模型的拟合效果和预测效果比EMD-GM(1,1)模型和GM(1,1)模型好,具有更高的应用价值。  相似文献   

18.
Inter Simple Sequence Repeats(ISSR) markers were used to assess genetic diversity within and among populations of dwarf mountain pine(Pinus mugo Turra) growing in the Tatra National Park(UNESCO Biosphere Reserve) in Southern Poland(Central Europe). The analyzed population belongs to two different geobotanical sub-districts: the Western and High Tatras. The level of genetic diversity assessed in this study for P. mugo is generally comparable to that reported for the other pine species in the Pinaceae family assessed by ISSR markers, especially with respect to Nei’s genetic diversity and the percentage of polymorphic bands. Bayesian analysis clustered the analyzed populations into two groups, corresponding to their geobotanical locations in the Tatras. Significant divergence between the two genetical clusters was supported by the results of Analysis of Molecular Variance(AMOVA). According to the Mantel test, there was no correlation between the genetic distance and the geographical distance. The present study confirms the existence of two genetically distinct clusters of P. mugo populations in the Tatra Mountains. The observed high population-genetic differentiation of P.mugo in the Tatras could be attributed to several genetic, environmental and historical factors occurring in this mountain area.  相似文献   

19.
Long chain alkyl diols have shown important potential for the reconstruction of sea surface temperature,productivities and upwelling conditions in marine or lacustrine environments.However,little is known about the distribution and sources of the diols in eastern China marginal seas(CMS),which are areas of important organic carbon sink.Here the contents of C_(30) and C_(32)1,15-diols were analyzed in 181 surface sediments from eastern CMS.The similar distribution pattern and strong linear correlation between C_(30) and C_(32) diols indicated that they had similar biological source,with a dominance of C_(30) diol.Their contents ranged from 7-2726 ng g~(-1) for C_(30) diol and 5-669 ng g~(-1) for C_(32) diol,and both showed higher values mainly in the mud area of the Yellow Sea,while the TOC normalized contents showed a more obvious seaward increasing trend.The similar distribution pattern and significant positive correlation between diols and the other marine biomarkers(brassicasterol,dinosterol,C_(37) alkenones) indicated C_(30) and C_(32) diols in eastern CMS were mainly from marine algae.This conclusion was also supported by principal component analysis(PCA).Our results also showed that sediment diol contents were generally related to marine productivity,suggesting that diols could be applied for marine productivity reconstruction in eastern CMS.  相似文献   

20.
尺度效应是地球科学和定量遥感中的重要研究课题,目前的许多研究大多集中在估算尺度效应带来的误差,而对一些关键的植被结构参数是否存在尺度效应及其尺度转换方法尚存在诸多不同见解。本文针对真实和有效叶面积指数(Leaf Area Index, LAI和Effective LAI, LAIe)以及聚集指数(Clumping Index, CI)3个植被关键结构参数,从基本概念和获取方法上分析参数的尺度效应及其尺度转换方法。从定义上看,LAI并不存在尺度效应,而LAIe和CI则存在尺度效应,其中CI的尺度效应由LAIe引入(CI=LAIe/LAI)。在野外实测中,LAI破坏测量法没有尺度效应,但由孔隙率模型获取3个参数的方法均具有尺度效应。异速生长方程和遥感反演方法的尺度效应取决于方法本身的线性或非线性特征。目前全球主要的LAI、LAIe和CI遥感产品都基于非线性模型获取,其反演过程具有尺度效应。像元尺度的LAI本身并不具有尺度效应,而像元尺度的LAIe和CI虽然具有尺度效应,但在实践中常常被忽略。因此,实际工作中应注意区分参数概念本身、野外测量、遥感反演方法以及遥感产品等所展示的不同尺度效应。  相似文献   

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