海洋平台甲板落物分析研究及应用

针对庞杂的落物分析方法和数据库,文章梳理和对比了海洋平台甲板落物分析基本数据的来源和分析方法,探讨了落物分析方法的边界条件,并将方法应用到某实际项目中,进而验证了方法的适用性和合理性。

基于塑性理论的海洋平台落物分析

海洋石油平台的工作环境较为复杂,在设计此类平台时,除了考虑平台自重及其受到的冰荷载、环境荷载、建造和安装时产生的事故荷载以外,还需考虑其在正常运行过程中物体坠落冲击载荷引起的应力集中。由此,对海洋平台的局部结构或整体结构进行落物评估分析,以验证其受力是否满足强度要求。采用Sesam软件建立分析模型,并采用USFOS软件进行落物时程分析,得到落物构件承载能力的变化规律;以能量法为依据,为海洋平台结构的设计优化和计算校核提供参考。

陵水17-2半潜式生产储油平台落物风险分析

落物风险是海上浮式生产设施的主要风险之一,开展平台落物风险分析对保障海上油气安全生产具有现实意义。本文识别了陵水17-2半潜式生产储油平台的主要落物风险区域,根据落物风险区域划分了4种吊机工况;基于国外海上油气行业的统计数据,计算了该平台落物频率和冲击能量关联曲线,分析了万年一遇风险可接受标准下各落物风险区域所能接受的最大冲击能量。本文分析结果有助于指导陵水17-2半潜式平台的落物保护设计,避免冗余安全设计导致的成本增加。

Correlations Between Plant Biomass and Soil Respiration in a Leymus chinensis Community in the Xilin River Basin of Inner Mongolia

This paper reports on two years of measurement of soil respiration and canopy-root biomass in a Leymus chinensis community in the Xilin River basin of Inner Mongolia. Correlations between components of plant biomass and soil respiration rates were examined. From respiration data based on CO2 uptake by NaOH and corresponding root biomass values for each run of 10 plots, a linear regression of CO2 evolution rates on root dry weights has been achieved for every ten days. By applying the approach of extrapolating the regressive line to zero root biomass, the proportion of the total soil respiration flux that is attributable to live root respiration was estimated to be about 27% on average, ranging from 14% to 39% in the growing season in 1998. There were no evident relations between the total canopy biomass or root biomass and CO2 evolution rates, but a significant exponential relation did exist between tire live-canopy biomass and CO2 evolution rates.

Comparative study on bioleaching of two different types of low-grade copper tailings by mixed moderate thermophiles

The bioleaching of two different types of low-grade copper tailings,acid-leaching tailings(ALT)and copper flotation tailings(CFT)by mixed moderate thermophiles,and the variation of mineralogical and microbiological characteristics during their dissolution processes were comparatively investigated.Results showed that bioleaching behaviors of the two types of tailings were significantly different.In ALT bioleaching,lower redox potential,higher[Fe3+]/[Fe2+]ratio and higher cell density in solution were obtained.These resulted in higher total copper,primary copper sulfide and secondary copper sulfide extractions,compared with CFT bioleaching.X-ray diffraction analysis suggested that gypsum and some metal organic complexes were detected in CFT bioleaching,which could cause the sluggish oxidation of sulphide minerals.The shifts of microbial community in the leachates and leaching residues varied greatly between ALT and CFT bioleaching.The percentage of iron-oxidizing bacteria in ALT bioleaching was higher than that of CFT,but the sulfur-oxidizing bacteria percentage was the opposite.The archaeon F.thermophilum L1 was detected in ALT but not in CFT.

The Influence of Key Environmental Variables on Phytoplankton Community Structure in the Estuary of Tidal Rivers Around Luoyuan Bay,China

A total of 348 species belonging to 8 phyla and 125 genera were observed in seasonally sampled phytoplankton of tidal rivers from 13 sampling sites around Luoyuan Bay, and all field samplings were carried out in productive period(March/June/August/December) at ebb tide. Bacillariophyta species were the most abundant species, followed by Chlorophyta, Cyanophytes, Euglenophyta, Cryptophyta, Dinophyta, Xanthophyta and Chrysophytas. Seasonal distribution index(SDI) value ranged from 0.63 to 0.86, which meant that species found at those sites in 4 seasons tended to be largely different. Phytoplankton individuals ranged from 5.939×10~4 ind L^(-1) in winter to 75.31×10~4 ind L^(-1) in autumn. Phytoplankton biomass ranged from 0.620 mg L^(-1) in summer to 2.373 mg L^(-1) in autumn. The grey correlation analysis(GCA) showed that the nutrient variables played an important role in the influence on phytoplankton community in every season. The canonical correspondence analysis(CCA) revealed impact of environmental variables on the different species, most of Bacillariophyta species were negative correlation with nutrients(TP and NH_3-N) in the four seasons, Chlorophyta species and Cyanophyta species did not show obvious correlation with environment variables in every season. The combination of GRA analysis and CCA analysis provided a method to quantitatively reveal the correlation between phytoplankton community and environmental variables in water body of tidal rivers at this region.

Characterization of Specific Spoilage Bacteria and Volatile Flavor Compounds of Flavored Crayfish

It is a common issue in the processing industry of crayfish that flavored crayfish stored at room temperature is perishable.In order to establish an effective putrid prediction mechanism,high-throughput sequencing and solid phase microextraction gas chromatography-mass spectrometry(SPME-GCMS)were used to analyse the microbial community structure and volatile flavor compounds of normal and putrid crayfish.The results showed that Aeromonas(57%),Macrococcus(7.7%),Vibrio sp.(6.6%),Acinetobacter(5%),Citrobacter(4.9%)and Enterobacter(1.49%)were the main bacterial genus in the refrigerated fresh crayfish(HNA).And Staphylococcus(17.04%),Aeromonas(4.46%),Xanthomonas(4.16%),Streptococcus(4.62%)and Enterococcus(2.77%)were the main bacterial genus in the marinated and refrigerated crayfish(HND).With the spoilage of samples(HNE and HNC),the diversity of bacteria decreased,and the specific spoilage bacteria grew rapidly,mainly Enterococcus,Bacillus,Lactobacillus,Leuconostoc,Weissella.Meanwhile,the volatile compounds in non-spoilage sample(HNA and HND)were mainly alkane compounds,aldehydes compound and esters compounds;and the volatile compounds in spoilage samples were mainly alcohols,acids,benzene compounds,terpenoids,N-containing compounds,S-containing compounds and ethers.This indicated that the contents and types of volatile compounds changed with the sample spoilage and deterioration.Correlation analysis results showed that Enterococcus,Lactobacillus and Bacillus were significantly positively correlated with alcohols,acids,benzene,terpenoids,N-containing compounds,S-containing compounds and ether compounds,while Aeromonas,Megasphaera,Acinetobacter,Citrobacter and Vibrio were significantly positively correlated with alkane compounds and esters compounds,and Leuconostoc were significantly positively correlated with alcohol compounds.These results can provide a theoretical guidance for the storage of cooked flavor crayfish at room temperature.

Effects of a Brine Discharge over Bottom Polychaeta Community Structure in Chabahar Bay

The brine discharge from desalination plants affects the benthic communities. Polychaetes are indicators to assess marine pollution. The aim of this study was to examine the effects of brine discharge over softbottom polychaete community in Chabahar Bay. Forty-two sediment samples were collected from seven stations in pre summer monsoon （April 2011） and post winter monsoon （October 2011） using Van Veen grab sampler. Changes in the polychaeta data assemblages were analyzed using univariate and multivariate techniques. Thirty-one polychaete species were identified with the highest abundance in station 6 in pre monsoon period and the lowest abundance in station 1 in pre monsoon. The results showed that the abundance, richness and diversity indices were decreased in the stations near the discharges area comparing to control stations far from the brine discharges zone. CCA （Canonical correspondence analysis） showed that salinity and temperature have influenced the community structure of polychaeta.

Site-Floristic Variability of Foxteil Meadows in Poland

On the basis of multifaceted investigations of approximately 600 phytosociological surveys of foxtail meadows taken in years 2002-2012 in river valleys with the assistance of the Braun-Blanquet method, the authors carried out evaluation of the floristic composition with respect to phytosociological structure, floristic variability, degree of synanthropisation and life form structures. In addition, they ascertained the dependence of floristic variability of Alopecuretum pratensis phytocenoses on site conditions determined using： the phytoindication method and the laboratory analyses assessed the soil content of available forms of P and K and of Mg. The greatest areas among the recognised syntaxons are taken up by patches of a typical sub-association developed in fresh sites on soils of lightly acid reaction and moderate nitrogen availability. Floristic variability of Alopecuretum pratensis is characterised by： presence in the phytosociological structure of species characteristic for other syntaxons, floristic abundance and botanical structure, domination of species of the 1 st and 2nd degree of stability, high proportion of synanthropic species, values of the floristic diversity index （H＇）, natural and fodder score values. Geobotanical variability of foxtail meadows confirms difficulties with unequivocal determination of the systematic position of the Alopecuretum pratensis association.

Soil Microbial Community-Level Physiological Profiling as Related to Carbon and Nitrogen Availability Under Different Land Uses

The goal of this work was to assess soil microbial respiration, determined by the assay of community-level physiological profiling in an oxygen-sensitive microplate （O2-CLPP）, in response to endogenous C and several individual C substrates in the soils with different organic C contents （as a function of soil type and management practice）. We also used the O2-CLPP to determine the respiratory response of these soils to endogenous C and amended C substrates with N addition. A respiratory quotient （RQ） was calculated based on the ratio of the response to endogenous soil C vs. each C-only substrate, and was related to total organic carbon （TOC）. For assessing N availability for microbial activity, the effect of N supplementation on soil respiration, expressed as Nr^tio, was calculated based on the response of several substrates to N addition relative to the response without N. Soils clustered in 4 groups after a principal component analysis （PCA）, based on TOC and their respiratory responses to substrates and endogenous C. These groups reflected differences among soils in their geographic origin, land use and C content. Calculated RQ values were significantly lower in natural forest soils than in managed soils for most C-only substrates. TOC was negatively correlated with RQ （r = -0.65）, indicating that the soils with higher organic matter content increased respiratory efficiency. The N addition in the assay in the absence of C amendment （i. e., only endogenous soil C present） had no effect on microbial respiration in any soil, indicating that these soils were not intrinsically N-limited, but substrate-dependent variation in Nr^tio within soil groups was observed.

Litter age interacted with N and P addition to impact soil N_(2)O emissions in Cunninghamia lanceolata plantations

Litter decomposition impacts carbon(C)and nutrient cycling.Nitrogen(N)and phosphorus(P)addition as well as litter age impact litter decomposition.Effects of nutrient addition and litter age on litter decomposition may impact emissions of soil nitrous oxide(N_(2)O),which is an important greenhouse gas.However,no study has examined the effects of interactions between litter age and nutrient addition on soil N_(2)O emissions,and explored the underlining mechanisms simultaneously,thus limiting our evaluation of litter decomposition effects on N_(2)O emissions.Litter with different age was collected from Cunninghamia lanceolata plantations experienced N and P addition treatments to examine the effects of nutrient addition and litter age on N_(2)O emissions by incubation study.Litter age generally increased N_(2)O emissions via a decrease in litter C:N ratio.While P addition decreased N_(2)O emissions,N addition increased them mainly by positive effects on soil enzymes as indicated by microbial functional genes associated with N_(2)O production and negative effects on litter C:N ratio.Litter age and nutrient addition interacted to impact soil N_(2)O emissions.In future forest management,both nutrient addition and litter age should be considered in evaluation of management effects on N_(2)O emissions,especially thinning or selectively cutting involving litter input with different age.

New Primers for Denaturing Gradient Gel Electrophoresis Analysis of Nitrate-Reducing Bacterial Community in Soil

The narG gene is frequently used as a molecular marker for bacterial nitrate-reducing community analysis. In this study, a new set of primers targeting the narG gene was designed and applied to semi-nested polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） assay. The potential of the new primers was verified on DNA directly extracted from soils from five different experimental sites distributed in Central and Southern Italy. Specificity of the primers was determined by excision, amplification, and sequencing of bands resolved by DGGE. A phylogenetic analysis showed the correlation between the sequences retrieved from the soils studied and the narG sequences from βand y-Proteobacteria. These primers expanded the existing molecular tools for ecological study on the size and diversity of nitrate-reducing bacterial community in soil.