广西近年高温干旱气象灾害及对电力供求的影响

通过对广西2003~2005年高温、干旱天气气候事件及其对电力供求影响的分析发现:广西2003~2005年高温、干旱灾害强度偏强,频率增大;最高气温与最大电力负荷有明显的正相关关系,高温灾害天气造成电力负荷呈大幅度增加的趋势;季节性、持续性的干旱造成广西水电发电量呈负增长状态。由于电力负荷加大,水电发电量供应不足,使广西电力供求呈紧张的局面,2003~2005年出现了不同程度的拉闸限电现象。     

Soil resource supply influences faunal size–specific distributions in natural food webs

The large range of body-mass values of soil organisms provides a tool to assess the ecological organization of soil communities. The goal of this paper is to identify graphical and quantitative indicators of soil community composition and ecosystem functioning, and to illustrate their application to real soil food webs. The relationships between log-transformed mass and abundance of soil organisms in 20 Dutch meadows and heathlands were investigated. Using principles of allometry, maximal use can be made of ecological theory to build and explain food webs. The aggregate contribution of small invertebrates such as nematodes to the entire community is high under low soil phosphorus content and causes shifts in the mass–abundance relationships and in the trophic structures. We show for the first time that the average of the trophic link lengths is a reliable predictor for assessing soil fertility responses. Ordered trophic link pairs suggest a self-organizing structure of food webs according to resource availability and can predict environmental shifts in ecologically meaningful ways. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to all users.     

腐殖酸可降低纳米银的水生生物毒性

本文作者主要研究了腐殖酸对聚乙烯吡咯烷酮包覆的纳米银颗粒(polyvinylpyrrolidone-coated AgNPs)毒性的影响,受试生物涵盖了水生系统不同的营养级别,包括藻类(Raphidocelis subcapitata)、水蚤类(Chydorus sphaericus)以及淡水鱼类(Danio rerio)。结果显示,腐殖酸可降低AgNPs对本研究中所有水生生物的毒性,并具有明显的剂量效应关系。原因为：1）腐殖酸使AgNPs表面带有更多负电荷,这阻碍了AgNPs与藻细胞的接触,使毒性降低;2）腐殖酸抑制了AgNPs中Ag⁺的溶出,而本研究显示自由Ag⁺的毒性高于团聚的纳米银颗粒。
精选自Zhuang Wang, Joris T.K. Quik, Lan Song, Evert-Jan Van Den Brandhof, Marja Wouterse and Willie J.G.M. Peijnenburg. Humic substances alleviate the aquatic toxicity of polyvinylpyrrolidone-coated silver nanoparticles to organisms of different trophic levels. Environmental Toxicology and Chemistry: Volume 34, Issue 6, pages 1239–1245, June 2015. DOI: 10.1002/etc.2936
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2936/full
     

A stochastic forest fire growth model

We consider a stochastic fire growth model, with the aim of predicting the behaviour of large forest fires. Such a model can describe not only average growth, but also the variability of the growth. Implementing such a model in a computing environment allows one to obtain probability contour plots, burn size distributions, and distributions of time to specified events. Such a model also allows the incorporation of a stochastic spotting mechanism.

Penguin colonies as secondary sources of contamination with persistent organic pollutants

Although long-range atmospheric transport has been described as the predominant mechanism for exposing polar regions to persistent organic pollutants (POPs), recent studies have suggested that bird activity can also contribute substantially to contaminant levels in some environments. However, because the species so far reported have all been migratory, it has not been demonstrated conclusively whether locally elevated contamination represents transport from lower latitudes by the migrating birds or, alternatively, redistribution and concentration of contaminants that were already present in the high-latitude environments. The present study demonstrates, for the first time, that several POPs are present in elevated concentrations in an environment frequented by a non-migratory species (Adélie penguins) that spends its entire life in the Antarctic. Levels of POPs, such as p,p'-DDE, hexachlorobenzene (HCB), chlordanes (CHLs) and polychlorinated biphenyls (PCBs), were 10 to 100-fold higher in soil samples from penguin colonies than from reference areas. This significant difference is likely related to local penguin activity, such as a higher abundance of guano and the presence of bird carcasses. This hypothesis is also supported by a higher percentage of persistent congeners (PCB 99, 118, 138 and 153) in the soil from the colonies compared to the reference areas. This profile of PCB congeners closely matched profiles seen in penguin eggs or penguin blood.     

Effects of cross-substrate interaction on biotrickling filtration for the control of VOC emissions

The effects of cross-substrate interaction to the performance of a gas-phase biotrickling filter for treating a mixture of volatile organic compounds (VOCs), including three structural heterologous in acetone, toluene, and trichloroethylene, were investigated. The biotrickling filter was inoculated with microbial consortium containing at least seven bacterial species utilizing either acetone or toluene, or both, as their carbon sources. In the performance study, the column operating under variable conditions typifying the waste gas emission from the microelectronics fabrication processes achieved a total hydrocarbon (THC) removal efficiency in excess of 85% and a mineralization capacity over 50% for THC mass loading as high as 36.2 g-CH4 m-3h-1. The cross-substrate effects were examined by correlating the relative changes in the mass removal of each substrate with the biodegradative capability of the microbial consortium. The degradation of trichloroethylene was primarily due to co-metabolism by the toluene-oxidizing enzymes, but the results also indicated that trichloroethylene partially induced its own degradation. Concentration increases in acetone appeared to cause a diauxie effect that suppressed degradation of toluene and trichloroethylene, and shifted the microbial population toward the selective acetone-degraders. No irrecoverable toxicity or inhibitory effects were observed throughout the experiments. These results suggest that the relative VOC concentration in the waste gas mixture is a factor as important as the biodegradative function of the microbial consortium, and thus should be carefully evaluated to satisfy the treatment objectives.     

The citrus pyslla, Trioza erytreae (Del Guercio) (hemiptera: Triozidae): A review

The literature on the citrus psylla, Trioza erytreae, published since 1897, is reviewed. The citrus psylla is an important vector of the greening disease of citrus. The stages of development and life history are discussed. Of the factors that influence population size, flushing of the host plants and high saturation deficits are the most important. Methods of population monitoring and control are summarised. The main means of reducing vector numbers and therefore the spread of greening disease, are resistance of citrus trees to greening disease, restricting citrus growing to hot, low-lying regions of the country, and strict vector control in nurseries. Requirements for further research, are discussed.     

Sonographically determined anomalies and outcome in 170 chromosomally abnormal fetuses

Structural pathology and outcome were studied in 170 chromosomally abnormal fetuses. Numerical chromosomal abnormalities were established in 158 (93 per cent) cases, of which 110 (71 per cent) represented trisomies, 30 (18 per cent) Turner syndrome, and 18 (11 per cent) triploidy. Structural chromosomal abnormalities were diagnosed in 12 (7 per cent) cases. Gestational age at referral was significantly shorter for pregnancies with Turner syndrome than for the other chromosomal abnormalities. Referral before 20 weeks of gestation was mainly based on fetal structural pathology alone (92 per cent); after 20 weeks, patients were referred because of structural pathology combined with small for gestational age, oligohydramnios, or polyhydramnios. Referral as a result of suspected multiple organ pathology occurred in 73.5 per cent of pregnancies. An abnormal amniotic fluid volume was present in 59/170 (34.5 per cent) chromosomally affected pregnancies, i.e., oligohydramnios in 31 and polyhydramnios in 28 cases. Birth weight was below the tenth percentile in over half of the chromosomally abnormal fetuses, except for Turnersyndrome. Fetal outcome was poor, with a survival rate at 1 month of 30 per cent for trisomies which was mainly determined by trisomy 21 (14/18=77.5 per cent).