Influence of grain size on species-habitat models

High resolution remote sensing data facilitate the use of small-scale habitat features such as trees or hedges in the analysis of species-habitat relationships. Such data potentially enable more accurate species-habitat mapping than lower resolution data. Here, for the first time, we systematically investigated this hypothesis by altering the spatial resolution from 1 m up to 1000 m grain size in species-habitat models of 13 bird species. The study area covered the Nidda river catchment in central Germany, a large heterogeneous landscape of 1620 km². A high resolution habitat map of the area was converted to coarser spatial and thematic resolutions in seven steps. We investigated how model performance responded to grain size, and we compared the differential effects of spatial resolution and thematic resolution on model performance. Explained deviance (D²) of the bird models generally decreased with coarser spatial resolution of the data, although it did not decrease monotonically in all species. On average across all species, model D² decreased from 41.5 at 1 m grain size to 15.9 at 1000 m grain size. Ten species were best modelled at 1 m, two species at 3 m and one species at 32 m grain size. Model performance degraded continuously with increasing grain size, both in habitat generalist and habitat specialist bird species, and was systematically lower in habitat generalists. The higher model performance observed at finer grain sizes was most likely caused by the combination of three factors: (1) high spatial accuracy of bird records and (2) a more precise location and delineation of habitat features and, (3) to a lesser degree, by more habitat types differentiated in maps of finer resolution. We conclude that higher spatial and thematic resolution data can be essential for deriving accurate predictions on bird distribution patterns from species-habitat models. Especially for bird species that are sensitive to specific land-use types or to small-scaled habitat features, a grain size of 1-3 m seems most promising.     

北京市秋季大气气溶胶质量浓度谱分布特征的观测研究

为了研究不同天气形势和气象要素对不同粒径段的大气气溶胶质量浓度谱分布的影响,2010年秋季在北京市采用空气动力学粒径仪对0.5 ～20 μm的大气颗粒物进行了为期2个月的连续观测.结果表明,在不同天气形势和气团运动下,质量浓度谱分布差异明显.受到西北气流影响,在质量浓度较小的清洁天气,谱分布主要集中在粗粒径段(清洁天气).当天气以静稳为主,颗粒物质量浓度值中等偏高时,粗细粒径气溶胶分布中出现谱值相近的高峰(中等浑浊天气).在受到西南气流主要影响的高质量浓度的观测日中,细粒径气溶胶在谱分布中占主要地位(高浑浊天气).在相同气团影响的天气下,昼夜间质量浓度谱分布的谱型变化趋势一致.清洁天气保持了粗粒径段的单峰分布,中等浑浊和高浑浊天气呈双峰分布.清洁天气细粒径段谱值受光化学反应影响在日间略高于夜间.中等浑浊天气中质量浓度的谱值在夜间受相对湿度和温度变化影响有显著增加.高浑浊天气下,昼夜温湿差别小,谱分布未出现明显变化.     

天水市大气降尘组成特征及表面电性模拟研究

对甘肃省天水市麦积镇大气降尘粒度分布及主要矿物组成进行了分析,并以实际降尘ζ电位作为参照,根据降尘中主要矿物组成的质量百分比,提出了计算法和混合法两种模拟大气降尘在水溶液中表面电性的方法.结果表明,麦积地区大气降尘属于可吸入颗粒粒度尺寸范畴,其主要矿物组成与质量含量为：石英（57.08%）、方解石（27.79%）、钠长石（10.29%）、白云母（4.84%）. 大气降尘在纯水中呈电负性,且ζ电位随着水溶液pH增加而减小.通过对比实际降尘与拟合方法所得到的ζ电位,发现两种拟合方式与实际降尘的ζ电位具有相似的变化趋势.降尘中矿物组成主导着降尘表面电位的大小和变化趋势,其对降尘表面电位的贡献率是最主要的.     

Intrasexual selection in Mirza coquereli : evidence for scramble competition polygyny in a solitary primate

The primates of Madagascar (Lemuriformes) deviate from fundamental predictions of sexual selection theory in that polygynous species lack sexual dimorphism, have even adult sex ratios and often live in female-dominated societies. It has been hypothesized that intrasexual selection in these species is either reduced or primarily focused on traits related to scramble competition. The goal of this study was to examine these hypotheses by studying the mating system of a solitary nocturnal species, Mirzacoquereli. During a 4-year field study in western Madagascar, I captured and followed 88 individually marked animals. I found that adult males were significantly larger than females, providing the first evidence for sexual size dimorphism in lemurs. In addition, the adult sex ratio was biased in favour of females in 3 out of 4 years. There was no significant sex difference in canine size, however. Males showed pronounced seasonal variation in testis size with a 5-fold increase before and during the short annual mating season. During the mating season, males had more injuries than females and more than quadrupled their home ranges, overlapping with those of more than ten females, but also with about the same number of rivals. Only about one social interaction per 10 h of observation was recorded, but none of them were matings. Together, these results indicate that these solitary lemurs are clearly subject to intrasexual selection and that male-male competition is primarily, but not exclusively, of the scramble type. In addition, they suggest that the above-mentioned idiosyncracies may be limited to group-living lemurs, that social systems of solitary primates are more diverse than previously thought, and that the temporal distribution of receptive females is responsible for this particular male mating strategy. Received: 11 January 1997 / Accepted after revision: 18 April 1997     

城市间运输货车行驶工况构建与应用

为研究城市间运输货车行驶工况特性与典型工况构建方法。运用车载数据采集系统采集了在珠三角区域城市间运输的货运车辆行驶车速等瞬态数据。基于13个工况特征参数解析工况特性,运用运动学片段理论将工况速度数据分成284个工况片,基于主成分分析和聚类分析法将工况片分成5类,选出12片代表工况片,按工况片平均速度从小到大的顺序排列,再将工况时长等比例压缩至1 800 s后最终构建出典型行驶工况。构建工况与实测样本的各项特征参数符合度大于80%,结果表明提出的典型工况构建方法可行,构建工况符合城市间货运车辆实际运行特性。构建工况的最大车速为80 km/h,主要分布在60~80 km/h,C-WTVC工况在0~90 km/h较均匀分布,平均车速为41.0 km/h,较构建工况低15.8%。基于构建工况进行重型货车排放性能仿真测算,得出CO_(2e)排放因子为764.81 g/km,较C-WTVC工况测算值低10.97%,表明运行工况不同导致碳排放测算值有较大差异。     

Spatiotemporal dynamics of cell abundance, colony size and intracellular toxin concentrations of pelagic and benthic Microcystis in Lake Caohai, China

Lake Caohai has experienced extensive Microcystis blooms in recent years,and to improve its water quality,the local government carried out a series of water control measures.To better understand the dynamics of both pelagic and benthic Microcystis and their characteristics in Lake Caohai,we conducted a 1-year investigation from December 2015to December 2016 to gain a seasonal outlook on the distribution and dynamics of cell abundance,colony size and intracellular microcystins(MCs)of Microcystis.The results indicated that the Microcystis bloom occupied primarily the northeastern region and then moved gradually from lakeshore to lake center.The perennial southwesterly winds and the water inflow from northeast to southwest in Lake Caohai determined the spatiotemporal distribution of pelagic Microcystis.Benthic Microcystis was mainly distributed in the northeastern region in summer,occupied the lake center in autumn and then occupied the southeastern region in winter,determined by the sedimentation of pelagic Microcystis and the death of benthic Microcystis.Small colonies(20-60μm)overwintered more easily in both water column and sediment.The concentrations of intracellular toxin of benthic Microcystis were observed to be significantly higher than those of pelagic Microcystis.This might be because Microcystis synthesized large amount of MCs to acclimate to an unfavorable benthic environment.This knowledge on the dynamics of Microcystis expands our understanding of mechanisms underpinning the formation of Microcystis blooms.     

Influence of COM-peptides/proteins on the properties of flocs formed at different shear rates

Coagulation followed by floc separation is a key process for the removal of algal organic matter(AOM) in water treatment. Besides optimizing coagulation parameters,knowledge of the properties of AOM-flocs is essential to maximizing AOM removal.However, the impact of AOM on the floc properties remains unclear. This study investigated how peptides/proteins derived from the cellular organic matter(COM) of the cyanobacterium Microcystis aeruginosa influenced the size, structure, and shape of flocs formed at different shear rates(G). Flocs formed by kaolinite, COM-peptides/proteins and a mixture of the same were studied, and the effect of intermolecular interactions between floc components on floc properties was assessed. The coagulation experiments were performed in a Taylor–Couette reactor, with aluminum(Al) or ferric sulphate(Fe) utilized as coagulants. Image analysis was performed to gauge floc size and obtain data on fractal dimension. It was found that floc properties were affected by the presence of the COM-peptides/proteins and the coagulant used. COM-peptides/proteins increased floc size and porosity and widened floc size distributions. The Fe coagulant produced larger and less compact flocs than Al coagulant. Moreover, the decrease in floc size that occurred in parallel with increase in shear rate was not smooth in progress. A rapid change for the kaolinite-coagulant suspension and two rapid changes for the suspensions containing COM were observed. These were attributed to various intermolecular interactions between floc components participating in coagulation at different G. Based on the results obtained, shear rates suitable for efficient separation of flocs containing COM were suggested.     

具有不同粒径和相同表面结构纳米银颗粒的制备及表征

具有不同粒径相同表面结构AgNPs（nano-silver,纳米银）的可控合成是开展AgNPs毒性研究和风险评估的基础,也是材料制备领域的难点之一.采取化学还原的方法,使用AgNO₃（硝酸银）作为反应前体,使用TSC（trisodium citrate,柠檬酸三钠）和NaBH₄（sodium borohydride,硼氢化钠）作为稳定剂及还原剂,通过优化剂量比和反应条件等合成参数,一步式原位反应生成不同粒径的AgNPs.利用TEM（透射电子显微镜）、UV-Vis（紫外可见分光光谱）、ICP-MS（电感耦合等离子体质谱）、FT-IR（傅里叶转换红外光谱）和DLS（动态光散射）等技术综合表征了合成纳米颗粒的形貌和结构性质.结果表明:①TEM结果显示,3种AgNPs均为球形且粒径分别为12、25和33 nm.②UV-Vis表征结果显示,所得产物在391~408 nm之间有较强吸收,说明合成产物为AgNPs.③利用ICP-MS测试样品中未反应的ρ（Ag+）,得出该制备方法具有高产率（>99%）.④DLS结果证实了合成的AgNPs在水溶液中带负电荷且具有较窄的粒度分布.⑤FT-IR结果显示,所制备的AgNPs表面结构一致,具有碳碳双键、酯基、羧基和羟基等官能团,在材料制备的过程中,溶液的初始配比、反应时间及环境条件都会对反应结果产生很大影响.研究显示,通过化学还原方法制备的AgNPs具有方法简便、重现性好、产率高和单分散性的特点,所制备的系列AgNPs颗粒表面结构一致,具有良好的化学稳定性.      

Toxicity and mechanisms of action of titanium dioxide nanoparticles in living organisms

Titanium dioxide nanoparticles(TiO_2 NPs) are one of the most widely used nanomaterials in the consumer products, agriculture, and energy sectors. Their large demand and widespread applications will inevitably cause damage to organisms and ecosystems. A better understanding of TiO_2 NP toxicity in living organisms may promote risk assessment and safe use practices of these nanomaterials. This review summarizes the toxic effects of TiO_2 NPs on multiple taxa of microorganisms, algae, plants, invertebrates, and vertebrates. The mechanism of TiO_2 NP toxicity to organisms can be outlined in three aspects: The Reactive Oxygen Species(ROS)produced by TiO_2 NPs following the induction of electron–hole pairs; cell wall damage and lipid peroxidation of the cell membrane caused by NP-cell attachment by electrostatic force owing to the large surface area of TiO_2 NPs; and TiO_2 NP attachment to intracellular organelles and biological macromolecules following damage to the cell membranes.