安徽省长江以北地区土壤水溶性氟含量及分布特征

采集安徽省长江以北地区有代表性土壤样品３４７个，测定了其水溶性氟含量。结果表明，土壤水溶性氟含量范围０３８～１２６９ｍｇ／ｋｇ，平均为２３８ｍｇ／ｋｇ。地区分布是南低北高，以淮北宿州和阜阳地区为最高，平均含量在３ｍｇ／ｋｇ以上。主要土壤类型土壤水溶性氟含量顺序是砂姜黑土、潮土＞黄棕壤、紫色土＞水稻土＞石灰土、粗骨土。不同母质土壤水溶性氟含量顺序是古黄土性河湖相沉积物＞黄泛冲积物＞紫色砂岩＞下蜀黄土＞石灰岩＞酸性结晶岩风化物＞河流冲积物。土壤水溶性氟含量与土壤ｐＨ呈正相关。ｐＨ高的黄泛冲积物和古黄土性河湖相沉积物母质土壤含水溶性氟多，该土壤地区发生氟中毒可能性较大。     

杉木观光木混交林和杉木纯林群落细根生产力、分布及养分归还

研究了福建三明27a生杉机光木混交林和杉木群落细根（d＜2mm）的生产力、分布、和养分归还。结果表明，混交林细根生物量、N、P养分现存量分别为5．381thm^2、48．085kghm^-2和4．174kghm^-2，分别比杉木纯林增加17．4％、27．2％和20．0％，混交林林细根的年净生产力达4．124thm^-2a^-1，比纯林高出16．9％，混交林杉木和观光木细根均在表层土壤富集，而在较深层土壤再会得分布具镶嵌性；与混交林杉林相比，纯林杉木土吉表层细根量较少，最大分布层次下移，混交林中观光木细根的周转速率咪1．16，杉木为0．96和0．95；而林下植被层细根周转速率（1．46－1．52）均同于相应的乔木层，混交林细根的年死亡量、N和P养分年归还量分别达2．119thm^-2、18．559kghm^-21．565kgkhm^-2，分别是纯林的1．21倍、1．23倍和1．14 倍，其中林下植被细根占有较为重要位置，对细根分布与土壤性质的相关分析表明，细根的垂直分布与土壤全N的相关性最强（0．87－0．89）。     

Foraging responses of wild house mice to accumulations of conspecific odor as a predation risk

Many predators hunt using the social and waste odors of their prey. It is unknown, however, whether potential prey modify their behavior in response to the risks of predation associated with accumulations of conspecific odor. We examined this question by measuring foraging trade-offs of wild house mice (Mus domesticus) in the field where we increased both predation risk and conspecific odor at artificial food patches in a two-factor design. Mouse giving-up densities (GUDs) were significantly higher in open habitats than in closed habitats but did not differ with the addition of mouse odors. Fine-scale behavioral observations of captive mice confirmed their attraction to the conspecific odor in an enclosure experiment, without any change to the GUD. These results indicate that house mice continue to visit and forage at food patches despite accumulations of predator-attracting odors. This most likely occurs for the social benefits obtained from conspecific odor exploration; however, such behavior may cause mice to become vulnerable to considerable olfactory exploitation by their predators. Future work must therefore focus on how mice trade off the social benefits of investigating odors that also attract their enemies.     

Probability distributions and statistical inference for axial data

Observations on axes which lack information on the direction of propagation are referred to as axial data. Such data are often encountered in enviromental sciences, e.g. observations on propagations of cracks or on faults in mining walls. Even though such observations are recorded as angles, circular probability models are inappropriate for such data since the constraint that observations lie only in [0, π) needs to be enforced. Probability models for such axial data are argued here to have a general structure stemming from that of wrapping a circular distribution on a semi-circle. In particular, we consider the most popular circular model, the von Mises or circular normal distribution, and derive the corresponding axial normal distribution. Certain properties of this distribution are established. Maximum likelihood estimation of its parameters are shown to be surprisingly, in contrast to trigonometric moment estimation, numerically quite appealing. Finally we illustrate our results by several real life axial data sets. Received: September 2004/ Revised: December 2004     

源于大气的氟在水稻不同器官的分布及对糙米含氟量的影响

用开顶式熏气罩熏气的方法,研究了气源氟在水稻不同器官的分布及对糙米含氟量的影响。结果表明:气源氟主要分布于水稻叶片中,根含氟量不受气源氟的影响;籽粒含氟量取决于籽粒器官形成后空气氟浓度,与籽粒器官形成前的空气氟浓度无关;糙米氟含量与水稻抽穗齐穗后所暴露的氟剂量间呈极显著线性相关关系。     

Obtaining species: sample size considerations

Suppose fish are to be sampled from a stream. A fisheries biologist might ask one of the following three questions: ‘How many fish do I need to catch in order to see all of the species?’, ‘How many fish do I need to catch in order to see all species whose relative frequency is more than 5%?’, or ‘How many fish do I need to catch in order to see a member from each of the species A, B, and C?’. This paper offers a practical solution to such questions by setting a target sample size designed to achieve desired results with known probability. We present three sample size methods, one we call ‘exact’ and the others approximate. Each method is derived under assumed multinomial sampling, and requires (at least approximate) independence of draws and (usually) a large population. The minimum information needed to compute one of the approximate methods is the estimated relative frequency of the rarest species of interest. Total number of species is not needed. Choice of a sample size method depends largely on available computer resources. One approximation (called the ‘Monte Carlo approximation’) gets within ±6 units of exact sample size, but usually requires 20–30 minutes of computer time to compute. The second approximation (called the ‘ratio approximation’) can be computed manually and has relative error under 5% when all species are desired, but can be as much as 50% or more too high when exact sample size is small. Statistically, this problem is an application of the ‘sequential occupancy problem’. Three examples are given which illustrate the calculations so that a reader not interested in technical details can apply our results.     

多效唑在鱼体内的分布,积累与类脂质含量相关性研究

实验水系统中，植物生长调节剂多效唑在鲤科类金鱼体内分布、积累的研究结果表明，＾３Ｈ－ＭＥＴ主要积累在鱼体消化系统；各器官／组织的积累量依次为：肠＞肝＞鳃＞皮＞肉＞骨；多效唑效生物积累因子（ＢＣＦ）和鱼体类脂质含量之间有较高的正相关性。     

沈阳市烟囱分布对大气污染的影响

本文介绍采用航空遥感技术和实地调查研究相结合的方法,分析了沈阳市烟囱数量、高度、密度以及高、中、低架烟囱的分布状况和特点,同时与大气污染监测结果对照分析了沈阳市煤烟型大气污染的规律及特点,研究了沈阳市烟囱分布对大气污染的影响。最后,提出了沈阳市燃煤污染的防治途径。     

水生态修复对莲花湖底栖动物群落的影响

武汉莲花湖是典型的富营养化城市浅水湖泊．通过对其进行16mo的监测后发现，治理后的小莲花湖比大莲花湖水质有明显改善．监测期间小莲花湖底栖动物密度和生物量均值明显高于大莲花湖，Shannon多样性指数与Margalef多样性指数也高于大莲花湖．将大、小莲花湖的10种环境因子和底栖动物密度进行典型相关分析后，发现总磷、温度、总氮、叶绿素a、氨离子是对底栖动物群落具有显著性影响的环境因子．图8表3参20.     

厌氧发酵过程pH对微生物多样性和产物分布的影响

采用PCR-DGGE技术,研究了不同pH条件下蔬菜类有机垃圾厌氧发酵过程中的微生物多样性,探讨了微生物群落结构与发酵产物分布的关系.Shannon指数分析表明,pH=7和pH=8时的微生物多样性较高,随时间变化规律相似,而pH=5时的微生物多样性较低.UPGMA聚类分析和PCA分析结果也表明,pH=7和pH=8时的微生物群落结构相似,pH=5与之显著不同.在不同pH条件下的优势菌属都是乳酸细菌和梭菌。微生物多样性的变化与发酵产物分布具有一定相关性,pH通过影响微生物群落结构的变化最终影响发酵产物的分布.图4表2参27