金龙顶子火山喷发柱动力学参数的估算及其灾害评价

用厚度对数-面积平方根法求得金龙顶子火山四海期喷发物体积为0.2155km3。根据最大浮岩碎屑粒度等值线分布特征,估算四海期喷发柱气冲区高度2.5km、对流区高度10.0km、伞状区高度13.86km;风速25-30m/s;初始喷发温度800℃;喷火口半径50m;初始速度250m/s;质量喷发率106.54kg/s;体积喷发率103.26m3/s;喷发高峰时上升速度100m/s;喷发柱中央线温度210k;喷发柱宽度半径为2km;伞状区向外辐射速度20～7m/s;喷发持续时间约为32.91小时;释放能量为1.62×1019J。在火山喷发数值模拟软件模拟验证的基础上,对金龙顶子火山灾害进行了评价预测。     

碱渣对海洋水环境中PO_4~（3－）的吸附动力学特征

本文作为碱渣倾倒对海洋水环境影响现场调查的先期研究，从理论上推导了固─液体系的二级吸附动力学模型。在室内试验的基础上，利用该模型对碱渣─海水混合体系的吸附试验数据进行了理论分析。认为碱渣对海水中磷酸盐的吸附是二级动力学过程。并且提出了碱渣─海水体系中碱渣含量对吸附反应速率影响大小的“强度指数”概念。应用该模型预测了不同混合比例条件下碱渣对海水中不同初始浓度磷酸盐的平衡吸附量和平衡浓度。理论分析发现，预测的平衡吸附量和平衡浓度之间符合乔姆金等温吸附方程，说明了海水中磷酸盐在碱渣表面上的吸附是遮盖率不大的单层化学吸附，与本文的前提假设相符合。     

渤海湾海丰盐场卤虫种类组成与生殖特性

1999年7～10月对渤海湾海丰盐场卤虫自然种群的种类组成和生殖特性进行了研究，结果表明：(1)原来仅有孤雌生殖种群，如今孤雌生殖卤虫与两性生殖卤虫Artemia franciscana共存，且在8～10月份外来种A.franciscana占主要部分。(2)温度是影响休眠卵产生的重要环境因子。实验期间温度降低，卵生比例升高，到9、10月份已全部为卵生。(3)随温度降低，怀后代数有上升的趋势。多数月份卤虫怀后代数与盐度负相关。     

氯酚污染土壤的生物强化修复及其微生物种群动态变化的分子生物学监测

在氯酚污染的土壤中接种氯酚降解菌,研究了受污染土壤的生物强化修复.利用传统的微生物计数方法和现代分子生物学手段,研究了生物强化修复过程中微生物种群的动态变化情况.在受氯酚污染的土壤样品中,以氯酚为唯一碳源和能源,分离出了多株对氯酚具有较高降解能力的微生物,利用16S rDNA序列分析方法对部分微生物进行了种属鉴定.土壤中存在的土著的氯酚降解菌可以对低含量的氯酚(100mg·g-1)进行降解;但是当土壤中氯酚含量较高(500 mg·g-1)时,土著微生物的降解能力受到限制,这可能是高浓度的氯酚对土著的氯酚降解菌会产生毒性作用.接种外来微生物后,土壤中可以培养的氯酚降解菌的总数从开始的106CFU·g-1增加到108CFU·g-1,并且,在氯酚含量为100 mg·g-1的土壤样品中,微生物数目的增加比在氯酚含量为500 mg·g-1土壤样品中更快.这表明接种的外来微生物可以在土壤中很好地生长繁殖,有效地促进土壤中氯酚的生物降解.接种外来微生物可以减轻土壤中氯酚对土著微生物初期产生的不利影响.土壤中的氯酚可能会改变微生物种群结构.DGGE分析结果表明,在未受氯酚污染和受氯酚污染的土壤样品中,存在一些共同的DNA谱带,但谱带强度有明显的差异.在受污染的土壤中接种外来微生物进行生物强化,可以促进污染物的生物降解过程,是生物修复过程中的一种重要手段,有着广泛的应用前景,将在我国受污染环境的生物修复中发挥重要作用.     

象山港网箱养鱼区海水营养盐变化研究

于 2 0 0 0年 1～ 12月分析了浙江省象山港网箱养鱼区的水质变化规律 ,结果表明 :网箱内NO3 - N、NH4 N、NH3 N和IN全年平均值均明显高于鱼排外 ;从全年平均值来看PO43 - P不超标 ,但 2月和 10月PO43 - P高于四类水质标准 ;IN含量在全年均严重超标 ,且网箱内的值一般高于鱼排外 ,尤其是由养殖鱼类排泄导致的NH4 N和NH3 N更是如此。     

Adjustment of parental effort to manipulated foraging ability in a pelagic seabird,the thin-billed prion Pachyptila belcheri

An experiment was designed to examine in a long-lived seabird, the thin-billed prion (Pachyptila belcheri), how adults adjust their food provisioning strategy when their foraging abilities are reduced and when the chick's needs are increased. To reduce the foraging abilities of adults we impaired their flying ability by removing some flight feathers (handicapped), and to increase the food needs of the chick one parent was retained (single). Birds made either short foraging trips lasting 1–3 days, or long trips lasting 5–9 days. Control birds alternated long and short trips whereas single birds or handicapped birds made several successive short trips and thereafter a long trip. In each treatment, food loads tended to be heavier after long trips than after short trips, and single birds tended to bring heavier loads than control or handicapped birds. Birds in the three treatments lost similar amounts of mass after short trips and gained similar amounts of mass after long trips. However, the mass of handicapped birds declined through the experiment, while that of control and single birds remained stable. Although the proportion of chicks that died during the experiment was similar among the three treatments, the chicks fledged by a single bird were lighter than those in control nests. The results of the experiment suggest that thin-billed prions adjust their breeding effort differently to decreased flying ability or increased food demand by the chick. Single birds increase foraging effort without allowing their condition to deteriorate. Conversely, handicapped birds are unable to maintain their body condition while sustaining the chick at the same rate as control birds. It is suggested that in this long-lived seabird, adults probably adjust their breeding effort so that they do not incur the risk of an increased mortality, this risk being monitored by the body condition.     

Allelopathic potential of Medicago arborea, a Mediterranean invasive shrub

Summary. Biological invasions are nowadays a major problem in ecology. Allelopathy has been shown to be involved in such invasions, but this mechanism has been little studied in France. The objectives of this study were to evaluate the allelopathic potential of Medicago arborea, an invasive species in the French Mediterranean region. Foliar extracts were tested on three target species (Lactuca sativa, Lepidium sativum and Linum strictum). We showed that Medicago arborea has high allelopathic potential to affect the growth and germination of other species. Yellow flax (Linum strictum), native to the invaded area, was the most sensitive of the tested plant species to foliar extracts of Medicago arborea. Our study pointed out the role of allelopathy in processes leading to biological invasion, and more generally in population dynamics.     

Effects of foundress number on brood raids and queen survival in the fire ant Solenopsis invicta

In several ant species, colonies are founded by small groups of queens (pleometrosis), which coexist until the first workers eclose, after which all but one queen is killed. It has been hypothesized that, by producing a larger cohort of workers, cooperating queens may increase colony success during brood raids, a form of competition in which brood and workers from losing nests are absorbed into winning colonies. To test whether this benefit is sufficient to favor pleometrosis, newly mated queens of the fire ant Solenopsis invicta were assembled in groups of one, two, three, or four, reared in the laboratory until the first workers eclosed, then planted in the field in replicated assemblages. The proportion of colonies engaging in brood raids increased with average foundress number per nest and with colony density but was unaffected by variance in foundress number among interacting colonies. Within mixed assemblages of single-queen and multiple-queen colonies, queen number had no effect on the likelihood of engaging in raids or the probability of nest survival through the brood raiding period. However, following nearly 30% of raids, queens moved to new nests and displaced the resident queens. When queen relocation and subsequent mortality were accounted for, it was found that the survival of queens from four-queen groups was substantially higher than that of solitary queens. By contrast, the survival of queens from two-queen colonies was no greater than that of solitary queens. These results show that the competitive advantages of multiple-queen colonies are sufficient to counterbalance the increased mortality of queens within groups only when the number of foundresses is greater than two and when colonies are founded at high density. When colonies lose brood raids, the workers appear to abandon their mothers to join surviving colonies. However, in laboratory experiments, queens attempting to enter foreign nests were significantly more likely to displace the resident queen if their own daughters were present within the invaded nest. Thus, workers may be able to bias the probability that their mother rejoins them and displaces competing queens.     

Developing a CFD heat transfer model for applying high expansion foam in an LNG spill

Liquefied natural gas (LNG) is widely used to cost-effectively store and transport natural gas. However, a spill of LNG can create a vapor cloud, which can potentially cause fire and explosion. High expansion (HEX) foam is recommended by the NFPA 11 to mitigate the vapor hazard and control LNG pool fire. In this study, the parameters that affect HEX foam performance were examined using lab-scale testing of foam temperature profile and computational fluid dynamics (CFD) modeling of heat transfer in vapor channels. A heat transfer model using ANSYS Fluent® was developed to estimate the minimum HEX foam height that allows the vapors from LNG spillage to disperse rapidly. We also performed a sensitivity analysis on the effect of the vaporization rate, the diameter of the vapor channel, and the heat transfer coefficient on the required minimum height of the HEX foam. It can be observed that at least 1.2 m of HEX foam in height are needed to achieve risk mitigation in a typical situation. The simulation results can be used not only for understanding the heat transfer mechanisms when applying HEX foam but also for suggesting to the LNG facility operator how much HEX foam they need for effective risk mitigation under different conditions.     

LES – DFSD modelling of vented hydrogen explosions in a small-scale combustion chamber

Accidental explosions are a plausible danger to the chemical process industries. In the event of a gas explosion, any obstacles placed within the path of the flame generate turbulence, which accelerates the transient flame and raises explosion overpressure, posing a safety hazard. This paper presents numerical studies using an in-house computational fluid dynamics (CFD) model for lean premixed hydrogen/air flame propagations with an equivalence ratio of 0.7. A laboratory-scale combustion chamber is used with repeated solid obstacles. The transient compressible large eddy simulation (LES) modelling technique combined with a dynamic flame surface density (DFSD) combustion model is used to carry out the numerical simulations in three-dimensional space. The study presented uses eight different baffle configurations with two solid obstructions, which have area blockage ratios of 0.24 and 0.5. The flame speed, maximum rate of pressure-rise as well as peak overpressure magnitude and timing are presented and discussed. Numerical results are validated against available published experimental data. It is concluded that, increasing the solid obstacle area blockage ratio and the number of consecutive baffles results in a raised maximum rate of pressure rise, higher peak explosion overpressure and faster flame propagation. Future model development would require more experimental data, probably in a more congested configuration.