生态斑块粒度效应研究——以长三角地区无锡市为例

从人为干扰明显、生态性脆弱、幅度范围在1 000km2的角度出发,该文选取了长三角地区无锡市为研究对象。通过采用多因子加权叠加模型方法获取了研究区的生态斑块,借助景观指数等探讨了生态斑块粒度效应及其临界变化情况。结果表明:1)以生态斑块为研究斑块类型时,类型水平景观指数、景观水平指数和面积变化指数均具有明显粒度效应,并存在临界粒度和尺度域现象。2)三类指数的临界粒度一致为粒度2,即实际为60m;尺度域分别为(2,30)、(2,10)和(2,10),综合尺度域为(2,10),即实际为60～300m,是符合研究区特性的尺度域。在该尺度域范围内,指数粒度变化响应曲线变化平稳,蕴含的生态过程较为相似,进行尺度推绎具有可行性。     

Porosity and permeability in sediment mixtures

Porosity in sediments that contain a mix of coarser- and finer-grained components varies as a function of the porosity and volume fraction of each component. We considered sediment mixtures representing poorly sorted sands and gravely sands. We expanded an existing fractional-packing model for porosity to represent mixtures in which finer grains approach the size of the pores that would exist among the coarser grains alone. The model well represents the porosity measured in laboratory experiments in which grain sizes and volume fractions were systematically changed within sediment mixtures. Permeability values were determined for these sediment mixtures using a model based on grain-size statistics and the expanded fractional-packing porosity model. The permeability model well represents permeability measured in laboratory experiments using air- and water-based permeametry on the model sediment mixtures.     

Legal aspects of conserving native oysters in Scotland

Native oysters (Ostrea edulis) historically supported valuable fisheries in Scotland, but are now absent from areas of former abundance on the east coast and occur mainly in isolated populations in west coast sea lochs. The main contemporary threat is from unauthorized gathering. In most places, the exclusive right to gather is retained by the Crown, as a remnant of the feudal system, but in some areas the right has been acquired by individuals or institutions. A temporary right to gather oysters may be obtained by permit from the proprietor, or through a Several or Regulating Order made under shellfish fisheries legislation. The right to gather oysters is separate from ownership of the foreshore or sea bed on which they are located. To receive the maximum legal protection, oyster beds must be marked out, or the rights to them otherwise adequately made known. Wild or formerly-cultivated oyster beds may not meet this criterion and, in any case, enforcement is difficult in remote locations. It has been proposed that there should be a statutory public right to gather oysters. Were this to be created, then strong conservation measures would need to be implemented to protect native oysters from eradication by uncontrolled gathering.     

基于垂直订正和湿度订正方法估算川渝地区逐小时PM2.5

针对PM_2.5污染比较严重的川渝地区,本研究利用日本静止葵花卫星(Himawari-8)反演的气溶胶光学厚度(AOD)进行垂直订正和湿度订正估算川渝地区2017年—2018年09:00—16:00时的PM_2.5浓度。首先,基于气象观测的能见度(vis)数据与消光系数σa(λ)之间的关系,引入“标高(Ha)”对气溶胶光学厚度进行垂直订正;其次,根据匹配的气象和环境监测数据对每一个站点逐一拟合1—12月份的吸湿增长因子,并采用反距离加权空间插值(IDW)方法构建吸湿订正因子网格,从而进行湿度订正估算。研究结果表明,经垂直订正和湿度订正后,相比AOD与PM_2.5之间的相关性,“干”消光系数σ_dry与PM_2.5的相关性显著提高,相关系数(r)由0.12—0.45提高至0.32—0.69;验证09:00至16:00时卫星估算结果,相关系数(r)均大于0.7,均方根误差(RMSE)为18.59±2.26μg/m³;提取所有观测站点进行验证,r=0.82,RMSE=18...     

In situ impact of petrochemicals on the photosynthesis of the seagrass Zostera capricorni

We used photosynthetic activity (measured as chlorophyll a fluorescence) and photosynthetic pigment concentrations to assess the effect of pulsed exposures of aged crude oil (Champion Crude), dispersant (VDC) and an oil+dispersant mixture on the seagrass Zostera capricorni Aschers in laboratory and field experiments, using custom-made chambers. Samples were exposed for 10 h to 0.25% and 0.1% concentrations of aged crude oil and dispersant as well as mixtures of 0.25% oil+0.05% dispersant and 0.1% oil+0.02% dispersant. During this time and for the subsequent four day recovery period, the maximum and effective quantum yields of photosystem II (Fv/Fm and DeltaF/Fm' respectively) were measured. In the laboratory experiments, both values declined in response to oil exposure and remained low during the recovery period. Dispersant exposure caused a decline in both values during the recovery period, while the mixture of aged crude oil+dispersant had little impact on both quantum yields. In situ samples were less sensitive than laboratory samples, showing no photosynthetic impact due to dispersant and oil+dispersant mixture. Despite an initial decline in DeltaF/Fm', in situ oil-exposed samples recovered by the end of the experiment. Chlorophyll pigment analysis showed only limited ongoing impact in both laboratory and field situations. This study suggests that laboratory experiments may overestimate the ongoing impact of petrochemicals on seagrass whilst the dispersant VDC can reduce the impact of oil on seagrass photosynthesis.     

基于项目学习的文综学科融合探究——以“走进青岛纺织 寻找城市文化根脉”为例

基于项目学习的学科融合,突出以学生为中心,运用多学科知识解决真实问题。它符合学生发展的需求,是未来学科教学的一个发展方向。本文根据笔者的教学感悟阐述了学科融合的价值,并以"走进青岛纺织寻找城市文化根脉"这一融合地理、政治、历史学科的项目式学习实践为例,说明项目学习的特点、基于项目学习文综融合的方式方法、项目学习的收获以及需要注意的问题。     

Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301

We present results of new ASCA observations of the low-luminosity active galactic nucleus (LLAGN) NGC 4579 obtained on 1998 December 18 and 28, and we report on the detection of variability of an iron K emission line. The X-ray luminosities in the 2-10 keV band for the two observations are nearly identical (LX approximately 2x1041 ergs s(-1)), but they are approximately 35% larger than that measured in 1995 July by Terashima et al. An Fe K emission line is detected at 6.39+/-0.09 keV (source rest frame), which is lower than the line energy 6.73+0.13-0.12 keV in the 1995 observation. If we fit the Fe lines with a blend of two Gaussians centered at 6.39 and 6.73 keV, the intensity of the 6.7 keV line decreases, while the intensity of the 6.4 keV line increases, within an interval of 3.5 yr. This variability rules out thermal plasmas in the host galaxy as the origin of the ionized Fe line in this LLAGN. The detection and variability of the 6.4 keV line indicates that cold matter subtends a large solid angle viewed from the nucleus and that it is located within approximately 1 pc from the nucleus. It could be identified with an optically thick standard accretion disk. If this is the case, a standard accretion disk is present at the Eddington ratio of Lbol/LEdd approximately 2x10-3. A broad disk-line profile is not clearly seen, and the structure of the innermost part of accretion disk remains unclear.     

冲击粉碎法制备针状硅灰石微粉的研究

硅灰石是一种钙的偏硅酸盐类矿物,化学分子式为Ｃａ［ＳｉＯ３］,含４８－３％ＣａＯ和５１－７％的ＳｉＯ２。天然硅灰石常呈白至灰白色,玻璃到珍珠光泽,密度２－７８～２－９１ｇｃｍ３,硬度为４－５～５,通常为针状、放射状、纤维状集合体,甚至微小颗粒仍保持纤维状结构［１］。由于硅灰石具有特殊的纤维状结构及优良的物理、化学性质,使其在工业生产中有广泛的应用,如陶瓷、塑料、橡胶、冶金铸造、磨料、焊条、玻璃、矿棉、水泥、造纸、石棉代用品等［２,３］。随着研究的深入,对硅灰石在非陶瓷方面（造纸、涂料、塑料、石…