Isolation and algae-lysing characteristics of the algicidal bacterium B5

Water blooms have become a worldwide environmental problem.Recently,algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms.In this study,one strain of algicidal bacterium B5 was isolated from activated sludge.On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence,it was identified as Bacillusfusiformis.Its algae- lysing characteristics on Microcystis aeruginosa,Chlorella and Scenedesmus were tested.The results showed that:(1)the algicidal bacterium B5 is a Gram-negative bacterium.The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B.fusiformis reached 99.86%,so B5 was identified as B.fusiformis;(2)the algal-lysing effects of the algicidal bacterium B5 on M.aeruginosa, Chlorella and Scenedesmus were pronounced.The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-α.The greater the initial bacterial cell density,the faster the degradation of chlorophyll-α.The greater the initial algal cell density,the slower the degradation of chlorophyll-α.When the bacterial cell density was 3.6 x l07 cells/ml,nearly 90% of chlorophyll-αwas removed.When the chlorophyll-αconcentration was less than 550μg/L,about 70% was removed;(3)the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.     

A general model for tagging on multiple component fisheries: an integration of age-dependent reporting rates and mortality estimation

A major objective of analyzing multiple year tag return data in fisheries is to estimate fishing and natural mortality rates which may vary by age class and calendar year. To do this one needs to be able to estimate the reporting rates for the tags recovered. Some fisheries such as that for Southern Bluefin Tuna (Thunnus maccoyii) have multiple components with potentially different reporting rates for the tag returns. In this paper we develop a general model for multi-cohort, multi-year tag return analyses where there are multiple components to the fishery with potentially different reporting rates. We require the assumption that one component has a reporting rate of 100% (i.e., this could be the component of a boat based fishery where scientific observers are present). We show further how it is possible to partition the overall likelihood developed into two conditionally independent components. The first component of the likelihood is the standard multinomial likelihood that allows estimation of fishing and natural mortality rates. It uses the tag return matrix summed over all the components of the fishery. It requires an average reporting rate for the tag returns (where the average reporting rate is a weighted average of the individual reporting rates of the different components). The second component is also multinomial for the individual component tag returns and allows us to estimate individual component reporting rates. However, this requires that we augment our second component tag return likelihood with a catch data likelihood for the corresponding components. The methodology is illustrated on some Southern Bluefin Tuna tagging and catch data. We also discuss important model assumptions and give suggestions for future research including the integration of tag-return and catch at age data analyses.     

抚仙湖沉积物有机碳埋藏特征及来源解析

为探讨近百年来抚仙湖不同湖区沉积物中有机碳埋藏及其来源变化特征,以抚仙湖南北部沉积柱为研究对象,分析有机碳埋藏速率时空变化特征,利用正构烷烃及其分布特征对埋藏在沉积物中的有机碳来源进行解析.结果显示,抚仙湖沉积物中有机碳含量为1.79~29.39mg/g,有机碳埋藏速率为3.07~27.71g/（m²·a）,两者均随时间的增加呈现整体上升的趋势,1980年以来增长速度明显加快;沉积物中有机碳含量北部（8.70mg/g）小于南部（12.59mg/g）,但有机碳埋藏速率北部（13.54g/（m²·a））大于南部（8.29g/（m²·a））,这与抚仙湖南北部有机质来源类型及人类活动的加剧造成的流域环境变化有关;抚仙湖沉积物中正构烷烃碳数范围为C₁₂~C₃₃,整体以高碳数组分为主,奇偶优势明显,表明沉积物中有机质主要来源于高等植物,Paq指示水生植物中以沉水植物占主导优势,2C₃₁/（C₂₇+C₂₉）与ACL_27~33指示陆生高等植物来源中,草本植物与木本植物的贡献相当,水生植物在北部湖区贡献大于南部,陆生高等植物在南部湖区的贡献大于北部.     

我国工伤事故死亡率分析及其ARIMA预测

对我国工伤事故死亡率的历史数据进行分析,介绍ARIMA模型预测法。根据统计学理论,运用ARIMA模型,借助相关软件预测我国工伤事故死亡率,可知未来几年,工伤事故的千人死亡率总体上呈逐年下降的趋势;与移动平均法、指数平滑法预测结果作比较,可知ARIMA模型预测效果最佳;同时,由于影响工伤事故的因素很多,与长期预测相比,ARIMA模型更适合于对工伤事故死亡率作短期预测。     

Replacement males in the western bluebird: opportunity for paternity, chick-feeding rules, and fitness consequences of male parental care

In western bluebirds (Sialia mexicana), most pairs remain together for life and share equally in post-hatching parental care. We removed resident males of socially monogamous pairs during laying and after clutch completion to examine chick-feeding rules used by replacement males and current and future fitness consequences of paternal care. Replacement males were not infanticidal and 7 (47%) fed nestlings. Feeding replacement males and the females they joined fed at rates similar to controls. Females without a feeding replacement male compensated by feeding more themselves so that overall feeding rates were not compromised, but they reduced their brooding time. Unlike assisted females, unassisted females exhibited reduced nesting success and their 14-day-old chicks weighed less than controls. Field metabolic rates of unassisted females were 17% higher than those of control females, but the difference was not statistically significant. Older females were better able to raise young without the male's help than were yearling females. Female condition was not affected by male provisioning and unassisted females were as likely to survive to the next breeding season as assisted females. We found no future benefits of provisioning by replacement males; those that fed were no more likely to breed with the female on her subsequent attempt than were males that did not feed, and subsequent clutch sizes were not reduced for females rearing young without the male's help. These experiments suggest that male parental care increases nesting success in western bluebirds and that replacement males use an all-or-none rule to determine whether or not to feed chicks: if they are present during the fertile period they feed at typical rates; if they are not, they usually do not feed at all. Because chick-feeding by males is tied to opportunity for paternity, influences success in the current nest, and does not affect the male's future breeding success, it appears to be parental rather than mating effort. Received: 8 May 1998 / Accepted after revision: 23 July 1998     

高产水稻氮钾施用量最佳配比研究

求导了水稻目标产量的预测方程,不同氮钾施用水平的等产方程,以及氮钾最佳配比方程。根据上述方程推导出地力产量为6345kg／hm2的水稻田目标产量为8589kg／hm2,N与K2O施用量的最佳配比为11．22,即N139．4kg／hm2、K2O170．6kg／hm2。     

山地草地凋落物分解与凋落物水文功能

以云南马龙县退化山地草地为研究对象.在围栏封育条件下,对分解过程中不同分解状态的凋落物分解速率、最大持水率、有效截流率及自然持水率进行了分析.结果表明,随封育时间(分解时间)的推移.草地凋落物分解速率有所降低.在同栏封育条件下,草地凋落物的分解速率显著高于未围栏封育条件(F=7.647;P<0.01).随凋落物分解时间的推移,其最大持水率、有效截流率呈抛物线状.研究发现在凋落物分解过程中,凋落物最大持水率、有效截流率将会出现一个峰值,之后将随凋落物的分解,最大持水率、有效截流率呈下降趋势.在草地凋落物分解过程中,围栏封育条件与未围栏封育条件相比,凋落物最大持水率、有效截流率出现较早,而在240 d的分解试验期内,未围栏封育条件下最大持水率峰值尚未出现.凋落物分解速率与凋落物自然持水率呈正相关,在围栏封育条件下相关性达到显著水平(r=0.94;P<0.05);未围栏封育条件下相关性达到极显著水平(r=0.93;P<0.01).     

Development of sol–gel formulations for slow release of pheromones

A new type of dispenser for slow-release of sex pheromones and other semiochemicals was developed based on sol–gel polymers that can be useful for monitoring, mass trapping, and mating disruption in integrated pest management (IPM). Sol–gel matrices exhibit glass characteristics and allow control of the degree of cross-linking during the polymerization process in order to provide an optimal release rate for a particular pheromone. The advantages of sol–gel (silica) matrixes include keeping the added molecules chemically stable and enabling the sol–gel material to be applied in any desired thickness and pheromone quantity, and thereby readily modify release rates. In addition, sol–gels are primarily silica and water that are common in the environment and therefore safe for field dispensing. We developed a method for the entrapment of pheromones in sol–gel matrices that allowed release at an almost constant rate over many days in the field. For example, 2.5 mg (E)-5-decenyl acetate pheromone of peach twig borer, Anarsia lineatella, entrapped in various sol–gel formulations released 14–45 μg/day for up to 28 days. The codling moth (Cydia pomonella) pheromone in sol–gels was used in field tests to capture more codling moth males than unbaited control traps. We describe how the method may be modified to entrap other types of pheromones by making sol–gels with different pore sizes.     

Long-Term Monitoring of Scots Pine Litter Decomposition Rates Throughout Sweden Indicates Formation of a More Recalcitrant Litter in the South

Decomposition studies were carried out at sites throughout Sweden, including the four Integrated Monitoring sites. Scots pine needle litterbag weight loss measurements over 3 or 5 years were determined at 26 sites and repeated up to 27 times, depending on the site. Humus layer respiration rates were determined for 20 sites in 1987–1989 and repeated in 2007–2008. Partial Least Squares (PLS) regression was used to elucidate the relative importance of climatic and soil factors. Annual needle weight losses decreased only slowly (20–10%) over 3–5 years for all northern (>60°N) sites but decreased sharply from 30 to 10% in the third year in southern (<60°N) sites. Respiration rates of southern sites were less (40% on average) than those of northern sites. Humus layer N was positively correlated to needle weight loss during the first and the second years, but negatively correlated in the third year and to respiration rates. The results indicated that litter formed in southern Sweden became more recalcitrant in later stages of decomposition compared to litter produced in northern Sweden.     

210Pb as a tool for establishing sediment chronologies: examples of potentials and limitations of conventional dating models

For aquatic sediments, the use of ²¹⁰Pb originating from the decay of atmospheric ²²²Rn is a well-established methodology to estimate sediment ages and sedimentation rates. Traditionally, the measurement of ²¹⁰Pb in soils and sediments involved laborious and time-consuming radiochemical separation procedures. Due to the recent development of advanced planar (‘n-type’) semi-conductors with high efficiencies in the low-energy range which enable the gamma-spectrometric analysis of the 46.5 keV decay line of ²¹⁰Pb, sediment dating using this radionuclide has gained renewed interest.In this contribution, potentials and limitations of the ²¹⁰Pb methodology and of the models used for estimating sediment ages and sedimentation rates are discussed and illustrated by examples of freshwater and marine sediments. Comparison with the use of ¹³⁷Cs shows that the information which may be gained by these two tracers is complementary. As a consequence, both radionuclides should be used in combination for dating of recent sediments. It is shown that for various sedimentation regimes additional information from other sources (e.g. sediment lithology) may be needed to establish a reliable chronology. A strategy for sediment dating using ²¹⁰Pb is recommended.