贵州省旱地土壤Hg污染状况与玉米安全生产评估

贵州省是我国Hg产量和储量最大的省份,玉米是其第二大粮食作物,有必要摸清贵州省土壤Hg含量状况,并评估其玉米生产安全性.在玉米主产区采集了990组土壤-玉米样品和270个土壤单一样品,测定土壤pH、阳离子交换量(CEC)和有机质(SOM)含量,以及土壤和玉米中Hg含量.结果表明,贵州省旱地土壤pH在3.93～9.82之间,ω(SOM)几何均值为27.5 g·kg^-1,CEC几何均值为11.7 cmol·kg^-1;土壤ω(Hg)范围为0.005～686 mg·kg^-1,几何均值为0.632mg·kg^-1,样点超标率为7.22%;其中,铜仁市土壤Hg污染最突出,超标率达21.3%;就县级而言,黔东南苗族侗族自治州丹寨县、铜仁市万山区和碧江区土壤Hg点位超标率较高;基于《食品安全国家标准食品中污染物限量》(GB 2762-2017),玉米籽粒Hg含量超标率为1.11%,超标点位主要分布于铜仁市万山区和安顺市西秀区等工矿业活动区周围.由结果可知,贵州省存在土壤Hg污染严重的情况,整体上玉米可实现安全种植,但...     

氮气泡沫灭火技术发展现状

介绍了氮气泡沫研究进展和现状,分析了氮气泡沫的灭火原理、稳定性以及应用实例。氮气是惰性气体,不溶于水,在水中扩散速率较小,其与泡沫液混合发泡产生的氮气泡沫与空气、二氧化碳等相比,具有持久惰化、稳定性好,灭火效果显著等优势。     

Greenhouse gas mitigation with scarce land: The potential contribution of increased nitrogen input

Agricultural lands have been identified to mitigate greenhouse gas (GHG) emissions primarily by production of energy crops and substituting fossil energy resources and through carbon sequestration in soils. Increased fertilizer input resulting in increased yields may reduce the area needed for crop production. The surplus area could be used for energy production without affecting the land use necessary for food and feed production. We built a model to investigate the effect of changing nitrogen (N) fertilizer rates on cropping area required for a given amount of crops. We found that an increase in nitrogen fertilizer supply is only justified if GHG mitigation with additional land is higher than 9–15 t carbon dioxide equivalents per hectare (CO₂-eq._./ha). The mitigation potential of bioenergy production from energy crops is most often not in this range. Hence, from a GHG abatement point of view land should rather be used to produce crops at moderate fertilizer rate than to produce energy crops. This may change if farmers are forced to reduce their N input due to taxes or governmental regulations as it is the case in Denmark. However, with a fertilizer rate 10 % below the economical optimum a reduction of N input is still more effective than the production of bioenergy unless mitigation effect of the bioenergy production exceeds 7 t carbon dioxide (CO₂)-eq._./ha. An intensification of land use in terms of N supply to provide more land for bioenergy production can only in exceptional cases be justified to mitigate GHG emissions with bioenergy under current frame conditions in Germany and Denmark.     

Ecotoxicological assessment of acid mine drainage: electrophysiological changes in earthworm (Aporrectodea caliginosa) and aquatic oligochaete (Lumbriculus variegatus)

Ecological health of 15 sites in two mining areas on the West Coast of the South Island, New Zealand, was assessed using a non-invasive electrophysiological technique. The conduction velocity (CV) changes in the medial giant fibres (MGF) of the terrestrial earthworm Aporrectodea caliginosa were measured on days 0, 1, 2, 4, 7, 14, and 21 following exposure to soil and/or sediment from six acid mine drainage (AMD) sites, and aquatic oligochaete Lumbriculus variegatus at 0, 3, 6, and 24 h following exposure to water from 14 AMD sites. The colour of the soil/sediments varied from red-brown to black with pH ranging from 4.46 to 7.37. The colour of AMD water samples varied from clear, black, brown to orange, and the pH ranged from 2.99 to 7.66. The CV decreased progressively in A. caliginosa exposed to most soil and sediment samples from the AMD sites (compared with controls exposed to soil from an organic farm) and this was most evident in measurements taken at 7 days. Based on the CV measurements taken on day 7, sites 3 > 2 > 1 were significantly (P < 0.05) the most toxic to earthworms. The CV of L. variegatus exposed to AMD water sampled from many sites also decreased progressively and this was significantly lower than the controls in the measurements taken at 24 h from sites 3 > 9 > 7 > 11. It is proposed that MGF CV in A. caliginosa and L. variegatus worms can be used as a non-invasive, sensitive, biomarker to monitor the toxicity of AMD sites.     

Marine gold and atoll livelihoods: The rise and fall of the bêche‐de‐mer trade on Ontong Java,Solomon Islands

The rise and fall of the bêche‐de‐mer trade in Solomon Islands is an example of how small, remote island communities are influenced by drivers of change on both the national and international scales. This susceptibility leads to local economic collapses and changed livelihoods. This article focuses on small‐island livelihoods, socio‐economic responses to fluctuating markets and the instability caused by internal and external forces of change. Quantitative surveys, qualitative interviews and participant observation have been used to explore the development trajectories of Ontong Java, a Polynesian outlier in Solomon Islands, in the context of the bêche‐de‐mer trade over the past forty years. The main findings can be captured in four distinct periods that demonstrate the transformation of this atoll community from subsistence‐oriented strategies to specialization in marine resource extraction to economic collapse and return to subsistence. It is concluded that this atoll population has shown a remarkable ability to adjust and cope with processes of globalization.     

Integrating Landscape Ecology and Geoinformatics to Decipher Landscape Dynamics for Regional Planning

We used remote sensing and GIS in conjunction with multivariate statistical methods to: (i) quantify landscape composition (land cover types) and configuration (patch density, diversity, fractal dimension, contagion) for five coastal watersheds of Kalloni gulf, Lesvos Island, Greece, in 1945, 1960, 1971, 1990 and 2002/2003, (ii) evaluate the relative importance of physical (slope, geologic substrate, stream order) and human (road network, population density) variables on landscape composition and configuration, and (iii) characterize processes that led to land cover changes through land cover transitions between these five successive periods in time. Distributions of land cover types did not differ among the five time periods at the five watersheds studied because the largest cumulative changes between 1945 and 2002/2003 did not take place at dominant land cover types. Landscape composition related primarily to the physical attributes of the landscape. Nevertheless, increase in population density and the road network were found to increase heterogeneity of the landscape mosaic (patchiness), complexity of patch shape (fractal dimension), and patch disaggregation (contagion). Increase in road network was also found to increase landscape diversity due to the creation of new patches. The main processes involved in land cover changes were plough-land abandonment and ecological succession. Landscape dynamics during the last 50 years corroborate the ecotouristic-agrotouristic model for regional development to reverse trends in agricultural land abandonment and human population decline and when combined with hypothetical regulatory approaches could predict how this landscape could develop in the future, thus, providing a valuable tool to regional planning.     

Adjustment of brood care behaviour in the absence of a mate in two species of Nicaraguan crater lake cichlids

In many taxa, parental strategies can vary among individuals. This is especially true in species with biparental care, with males, more often than females, deserting their mates. While there is an abundance of theoretical predictions and empirical data on factors inducing mate abandonment by males, much less is known about what consequences this may have on female behaviour, particularly in the field and in non-avian systems. Here, we compared brood defence rate, behavioural defence types, and brood success of solitary and paired females in two species of Neotropical cichlid fish in their natural habitat. In terms of the rate of territorial aggression towards potential brood predators, solitary females were able to fully compensate in the absence of a male but, in so doing, ended up maintaining smaller territories, which appeared to compromise offspring fitness in at least one of the two species. Hence, our results suggest that even extensive quantitative compensation in parental effort by solitary females may not be enough to ensure adequate qualitative compensation for the lack of male participation, highlighting the importance of distinguishing between these two aspects of compensatory parental care.     

Social monogamy and the threat of infanticide in larger mammals

The evolution of social monogamy in larger mammals is difficult to explain because males usually do not invest much in direct offspring care and might achieve greater fitness by deserting a pregnant female to reproduce with additional females elsewhere. It has been hypothesized that socially monogamous males remain with the female year-round to protect their offspring from infanticide by new immigrant males. We investigated this idea by analyzing all cases of infant loss in a wild population of white-handed gibbons (Hylobates lar; Primates), in which most groups were socially monogamous and some polyandrous (137.5 group years). We examined the influence of (a) male intruder pressure on male immigration rates and (b) the presence of a new male in the group on infant loss. We found no relation between intruder pressure and male immigration rates. Infant loss was lowest (4.5%) for stable monogamy (probable father stayed from conception through infancy) and intermediate (25.0%; p = 0.166) for stable polyandry. If a new male immigrated after conception, however, the infant was lost in all cases (p < 0.01) independent of the presumed father’s presence. Overall, 83.3% of infant losses were associated with the presence of a presumably unrelated male. Although the sample size is small, our results provide the first true support for the idea that the risk of infanticide is an important factor in the evolution of social monogamy in larger mammals.     

明日叶查尔酮对小鼠H22肝癌细胞增殖活性的抑制作用

为研究明日叶查尔酮(AC)对小鼠H22+肝癌细胞增殖的抑制作用,采用如下方法进行实验:1)将50只荷H22肝癌小鼠随机分为5组,每组10只.低、中、高剂量组每日分别灌胃给予5、20和40 mg·kg-1明日叶查尔酮,肿瘤对照组给予生理盐水,环磷酰胺(CTX)组隔天腹腔注射20 mg· kg-1的CTX.饲养10 d后处...