铜绿微囊藻和孟氏颤藻在富营养化湖泊中生长特征的模拟研究

为了模拟富营养化状态下2种蓝藻在湖泊中的生长特征,采用大型室内湖泊模拟装置进行了模拟研究,并通过三角瓶实验以及光合作用速率的响应实验对模拟装置中藻的生长特征进行了分析.湖泊模拟装置中,铜绿微囊藻和孟氏颤藻在对数生长期的特征生长速率分别为0.43d-1和0.32d-1,但对数生长期很短,仅3～4d.在对数期后有一个很长的"线性期",即生物量随时间近似成线性增长.在氮、磷较为充分的条件下,由于较强的光合作用导致了水体pH的升高,以及生物量增高导致了藻的自遮蔽作用,使藻的生长容易出现碳源限制和光限制.受水下光的影响,2种藻细胞内叶绿素a含量在对数期内一直增大.随后颤藻细胞内叶绿素a含量又逐渐降低,而微囊藻细胞内叶绿素a含量仍保持较高的水平,其原因可能是微囊藻能适应更高的pH.     

The Influence of the Pacific Decadal Oscillation on Annual Floods in the Rivers of Western Canada

We analyzed annual peak flow series from 127 naturally flowing or naturalized streamflow gauges across western Canada to examine the impact of the Pacific Decadal Oscillation (PDO) on annual flood risk, which has been previously unexamined in detail. Using Spearman's rank correlation ρ and permutation tests on quantile‐quantile plots, we show that higher magnitude floods are more likely during the negative phase of the PDO than during the positive phase (shown at 38% of the stations by Spearman's rank correlations and at 51% of the stations according to the permutation tests). Flood frequency analysis (FFA) stratified according to PDO phase suggests that higher magnitude floods may also occur more frequently during the negative PDO phase than during the positive phase. Our results hold throughout much of this region, with the upper Fraser River Basin, the Columbia River Basin, and the North Saskatchewan River Basin particularly subject to this effect. Our results add to other researchers' work questioning the wholesale validity of the key assumption in FFA that the annual peak flow series at a site is independently and identically distributed. Hence, knowledge of large‐scale climate state should be considered prior to the design and construction of infrastructure.     

Motivating landowners to recruit neighbors for private land conservation

Encouraging motivated landowners to not only engage in conservation action on their own property but also to recruit others may enhance effectiveness of conservation on private lands. Landowners may only engage in such recruitment if they believe their neighbors care about the conservation issue, will positively respond to their conservation efforts, and are likely to take action for the conservation cause. We designed a series of microinterventions that can be added to community meetings to change these beliefs to encourage landowner engagement in recruitment of others. The microinterventions included neighbor discussion, public commitment making, collective goal setting, and increased observability of contributions to the conservation cause. In a field experiment, we tested whether adding microinterventions to traditional knowledge-transfer outreach meetings changed those beliefs so as to encourage landowners in Hawaii to recruit their neighbors for private lands conservation. We delivered a traditional outreach meeting about managing the invasive little fire ant (Wasmannia auropunctata) to 5 communities and a traditional outreach approach with added microinterventions to 5 other communities. Analysis of pre- and post-surveys of residents showed that compared with the traditional conservation outreach approach, the microinterventions altered a subset of beliefs that landowners had about others. These microinterventions motivated reputationally minded landowners to recruit and coordinate with other residents to control the invasive fire ant across property boundaries. Our results suggest integration of these microinterventions into existing outreach approaches will encourage some landowners to facilitate collective conservation action across property boundaries.     

复合改性蒙脱土去除水体中颤藻的研究

为筛选用于景观水体水华应急治理的高效除藻材料,研究了十六烷基三甲基溴化铵(CTAB)和聚合氯化铝(PAC)复合改性蒙脱土去除颤藻的效果.以藻液浊度去除率和叶绿素a去除率表征除藻效果,通过单因素试验和正交试验确定复合改性蒙脱土去除颤藻的最佳配比、用量和操作条件.通过Zeta电位、生物显微镜和SEM形态表征分析了复合改性蒙脱土去除颤藻的机理.通过λ=420 nm处的透光率随时间的变化来反映其絮凝沉降速率的变化.结果表明,蒙脱土投加量为70 mg/L、PAC投加量为9 mg/L、CTAB投加量为0.875 mg/L、蒙脱土粒径为90 μm、pH值为8时,颤藻叶绿素a和浊度去除率分别可达到96.02％和93.9％.蒙脱土经复合改性后电荷翻转,沉降絮凝藻细胞的速率和效果增加.复合改性蒙脱土通过电荷吸附和网捕包裹作用吸附沉降藻细胞,改性剂CTAB使藻细胞失活,抑制藻絮体重新上浮.     

Extinction in a hyperdiverse endemic Hawaiian land snail family and implications for the underestimation of invertebrate extinction

The International Union for Conservation of Nature (IUCN) Red List includes 832 species listed as extinct since 1600, a minuscule fraction of total biodiversity. This extinction rate is of the same order of magnitude as the background rate and has been used to downplay the biodiversity crisis. Invertebrates comprise 99% of biodiversity, yet the status of a negligible number has been assessed. We assessed extinction in the Hawaiian land snail family Amastridae (325 species, IUCN lists 33 as extinct). We did not use the stringent IUCN criteria, by which most invertebrates would be considered data deficient, but a more realistic approach comparing historical collections with modern surveys and expert knowledge. Of the 325 Amastridae species, 43 were originally described as fossil or subfossil and were assumed to be extinct. Of the remaining 282, we evaluated 88 as extinct and 15 as extant and determined that 179 species had insufficient evidence of extinction (though most are probably extinct). Results of statistical assessment of extinction probabilities were consistent with our expert evaluations of levels of extinction. Modeling various extinction scenarios yielded extinction rates of 0.4‐14.0% of the amastrid fauna per decade. The true rate of amastrid extinction has not been constant; generally, it has increased over time. We estimated a realistic average extinction rate as approximately 5%/decade since the first half of the nineteenth century. In general, oceanic island biotas are especially susceptible to extinction and global rate generalizations do not reflect this. Our approach could be used for other invertebrates, especially those with restricted ranges (e.g., islands), and such an approach may be the only way to evaluate invertebrates rapidly enough to keep up with ongoing extinction.     

二苯并噻吩降解菌的筛选鉴定及煤脱硫的研究

从某石油化工厂的气浮池附近的土壤中,分离得到1株能降解二苯并噻吩的菌株DBZT,经菌株的形态特征、生理生化指标和16S rDNA序列分析,鉴定属于苍白杆菌属(Ochrobactrum sp.)。GC-MS分析菌株的发酵液,表明该菌株能将二苯并噻吩还原生成联苯。应用正交实验的方法研究了苍白杆菌DBZT在煤炭脱硫过程中煤粒度、菌液接种量和浸滤时间3个因素的组合对其脱硫效果的影响,并筛选出各因素的最佳实验条件。实验结果表明,浸滤时间对煤脱硫效率的影响最为显著。在浸滤时间为24 h,煤粒度小于0.094 mm,接种的细菌数量为3×106cfu/g煤样的条件下,菌株DBZT脱去全硫的效果最佳,达到16.28%。     

Arsenic contamination in water,soil, sediment and rice of central India

Arsenic contamination in the environment (i.e. surface, well and tube-well water, soil, sediment and rice samples) of central India (i.e. Ambagarh Chauki, Chhattisgarh) is reported. The concentration of the total arsenic in the samples i.e. water (n=64), soil (n=30), sediment (n=27) and rice grain (n=10) were ranged from 15 to 825 μg L⁻¹, 9 to 390 mg kg⁻¹, 19 to 489 mg kg⁻¹ and 0.018 to 0.446 mg kg⁻¹, respectively. In all type of waters, the arsenic levels exceeded the permissible limit, 10 μg L⁻¹. The most toxic and mobile inorganic species i.e. As(III) and As(V) are predominantly present in water of this region. The soils have relatively higher contents of arsenic and other elements i.e. Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Ga, Zr, Sn, Sb, Pb and U. The mean arsenic contents in soil of this region are much higher than in arsenic soil of West Bengal and Bangladesh. The lowest level of arsenic in the soil of this region is 3.7 mg kg⁻¹ with median value of 9.5 mg kg⁻¹. The arsenic contents in the sediments are at least 2-folds higher than in the soil. The sources of arsenic contamination in the soil of this region are expected from the rock weathering as well as the atmospheric deposition. The environmental samples i.e. water, soil dust, food, etc. are expected the major exposure for the arsenic contamination. The most of people living in this region are suffering with arsenic borne diseases (i.e. melanosis, keratosis, skin cancer, etc.).     

The Presence of Calcium Oxalate Dihydrate (Weddellite) in Street Sediments from Niterói, Brazil and Its Health Implications

Established research in first world urban environments has shown street sediments to be effective sinks for heavy metals and emphasises the health risks to children by its inhalation or ingestion. In third world countries with fewer pollution controls, contamination may be augmented by additional pollutants such as sewage discharge into urban streets and/or periodic inundation with sewage-laden run-off. This pollutant not only contains heavy metals and organic matter, but calcium oxalates that may derive directly from the sewage itself. To study this premise street sediments were collected from sites of varying industrialisation and sewage contamination within the city of Niteroi, Brazil. Calcium oxalate dihydrate (weddellite) was identified by X-ray diffraction, fourier transform infra red and scanning electron microscopy techniques and oxalate concentrations in <63m and colloidal (clay and organic matter) fractions, were determined by ion chromatography. Oxalate in colloidal fractions averaged 43601mgkg^–1 in sewage contaminated industrialised urban zones, 4519mgkg^–1 in suburban areas and 17477mgkg^–1 in suburbs with favelas (shantytowns-of Niterói). Oxalate concentrations coincide with high levels of metal ions (Fe, Mn, Zn, Pb, Ni, Cr) that stabilise calcium oxalate dihydrate and prevent its dehydration to the monohydrate (whewellite). Lower levels of oxalate were found in lichen-covered roof sediment, plaster and mortar samples. Oxalate concentration coincides with sewage contamination and street sediments appear to act as a sink for calcium oxalate dihydrate derived from sewage. Previous studies have shown that low levels of exposure can damage kidneys and the nervous system, while prolonged exposure can cause severe corneal, retinal and skin damage, cyanosis and possibly gangrene. Contact with blood serum may result in hypocalcemia, muscular stimulation, convulsions and finally collapse. The conditions described are common throughout urban areas of the developing world and may suggest a particular environmental hazard in these regions.     

Normal karyotype in cultured chorionic villus cells,but mosaicism in amniotic and fetal cells

A case with a normal male karyotype in cultured chorionic villus cells, but 46,XY/45,X/ 46,X,i(Yq) mosaicism in amniotic and fetal tissue is reported. The fetus was a phenotypic male. Pathological examination revealed discrete features, which might indicate a syndrome, and histological examination showed large, bright cells in the tubules of the testes. Possible explanations for discordance between the karyotype of embryonic and extraembryonic tissue are discussed.     

基于i1Mx-27的视频监控终端的设计和实现

介绍了一种基于新一代多媒体应用平台i.Mx-27和嵌入式Linux的图像采集和远程监控系统。阐述了系统各模块的硬件构成,系统的运行原理和软件设计。该终端实现了使远程PC通过Web浏览器方式进行实时视频监控。