Deviance partitioning of host factors affecting parasitization in the European brown hare (Lepus europaeus)

Deviance partitioning can provide new insights into the ecology of host-parasite interactions. We studied the host-related factors influencing parasite prevalence, abundance, and species richness in European brown hares (Lepus europaeus) from northern Spain. We defined three groups of explanatory variables: host environment, host population, and individual factors. We hypothesised that parasite infection rates and species richness were determined by different host-related factors depending on the nature of the parasite (endo- or ectoparasite, direct or indirect life cycle). To assess the relative importance of these components, we used deviance partitioning, an innovative approach. The explained deviance (ED) was higher for parasite abundance models, followed by those of prevalence and then by species richness, suggesting that parasite abundance models may best describe the host factors influencing parasitization. Models for parasites with a direct life cycle yielded higher ED values than those for indirect life cycle ones. As a general trend, host individual factors explained the largest proportion of the ED, followed by host environmental factors and, finally, the interaction between host environmental and individual factors. Similar hierarchies were found for parasite prevalence, abundance, and species richness. Individual factors comprised the most relevant group of explanatory variables for both types of parasites. However, host environmental factors were also relevant in models for indirect life-cycle parasites. These findings are consistent with the idea of the host as the main habitat of the parasite; whereas, for indirect life-cycle parasites, transmission would be also modulated by environmental conditions. We suggest that parasitization can be used not only as an indicator of individual fitness but also as an indicator of environmental quality for the host. This research underlines the importance of monitoring parasite rates together with environmental, population, and host factors.     

Fenton氧化破解剩余污泥中的胞外聚合物

利用Fenton试剂的强氧化性破解剩余污泥中的胞外聚合物（EPS）,通过释放出的多聚糖、蛋白质浓度以及SCOD的变化表征EPS的破解程度,旨在找出Fenton氧化破解EPS的适宜反应条件．结果表明,pH = 2.5,反应时间90 min,H₂O₂/Fe²⁺（质量比）= 8∶1,温度65～70℃为适宜反应条件．该条件下经Fenton氧化,污泥上清液中的SCOD、多聚糖和蛋白质浓度分别由45.88、 10.96和11.99 mg·L^-1增加到684.93、 382.17和302.62 mg·L^-1;污泥颗粒平均粒径和中值粒径分别由供试污泥的838.89 μm和859.20 μm减小到137.22 μm和148.69 μm．Fenton氧化可以有效破解污泥中的EPS,提高污泥的无机化程度,有利于污泥的减量化和资源化．     

农业非点源污染田间模型及其应用

非点源污染的负荷定量化研究是控制、评价和管理非点源污染的基础.农业非点源污染负荷估算包括农田排水估算和排水中的污染物浓度预测2个环节.依据水量平衡原理,农田排水应用DRAINMOD模型估算;将农田的施肥和灌溉过程"合成"作为田间污染物浓度的脉冲输入,农田排水中的污染物浓度变化则视作对应于此脉冲输入的响应过程,而污染物在田间的复杂迁移转化过程以逆高斯概率密度函数隐含表达.以此为基础,构建了农田尺度农业非点源污染负荷估算模型.以青铜峡灌区典型试验区为例,对稻田排水沟中硝态氮(NO_3~--N)和总磷(TP)的负荷过程进行了模拟,结果表明,模型估算结果和实测污染物负荷过程非常接近,Nash-Suttcliffe模拟效率系数分别为0.963和0.945,表明该模型具有较高的可靠性.     

Biodegradation and Ecotoxicity of Polyethylene Films Containing Pro-Oxidant Additive

The worldwide accumulation of non-degradable plastic materials, such as plastic bags, is one of the most important environmental concerns nowadays. The use of degradable materials is an option to mitigate the environmental impact generated by the consumption of plastics. One of the technologies used for the manufacture and use of degradable plastics is the use of pro-degradant additives that are incorporated in conventional plastics to promote their degradation under certain conditions. The aim of this study is to evaluate the process of oxidation, biodegradation and potential ecotoxicity of polyethylene films containing an oxo-degradable additive, according to the standard ASTM D-6954. This method establishes a procedure in which the samples are subjected to consecutive steps of accelerated oxidation, biodegradation by composting and ecotoxicity assessment. Furthermore, the effect of the presence of printing ink in the polyethylene samples with oxo-degradable additive was evaluated, and the results were compared with those obtained for samples of conventional polyethylene and polylactic acid. After 180 days of laboratory controlled composting, the samples reached the following percentages of biodegradation: polylactic acid, 41 %; printed oxo-degradable polyethylene, 32.24 %; oxo-degradable polyethylene, 25.84 %; printed polyethylene, 18.23 % and polyethylene, 13.48 %. The cellulose sample used as a control was mineralized in 58.45 %. Ecotoxicity assessment showed that the products of biodegradation of the samples tested, did not generate a negative effect on germination or development of the vegetal species studied. Under proper waste management conditions, these plastics can be used as an option to decrease the environmental impact of plastic films.     

基于灰色综合评价的通航安全角度下吴淞口建闸方案优选

将层次分析法与灰色关联分析法相结合,评价吴淞口挡潮闸3个备选方案对通航安全的影响。首先通过专家调查法,并对相关资料进行综合分析,确定吴淞口水闸建设工程方案通航安全影响评价指标,然后运用层次分析法计算各指标权重,最后利用灰色关联分析建立灰色评价模型,得到关联序,定量分析各方案在通航安全影响方面的优劣,得出最优方案,为吴淞口建闸方案的确定提供依据。     

Evaluation of noise environments during daily activities of university students

Noise conditions specifically in areas inside university facilities and its impact on the quality of life of university students are topics that have received little attention. This paper presents a study of the noise conditions in which university students of various institutions in Madrid, Spain, carry out their daily studies. A representative number of measurements was carried out using noise dosemeters and dataloggers in order to evaluate the levels of noise, noise dose and exposure to noise during school periods and extracurricular activities. The results were compared with the recommendations given by current environmental noise regulations. This paper was complemented with a survey to get to know how students perceive the exposure to noise in university environments.     

基于投影寻踪的资源环境综合绩效评估方法研究

资源环境综合绩效评估是建设节约型社会的一项基础工作.在传统的资源环境综合绩效指数中,各种资源消耗和污染物排放绩效的权重相等,导致综合评价结果的合理性受到影响.针对该问题,通过构建投影指标函数和采用遗传算法对投影方向进行优化,提出了基于投影寻踪的资源环境综合绩效评估方法,并应用于2007年中国各省、直辖市和自治区的资源环境绩效评估.研究结果表明,中国资源环境绩效水平空间差异明显,呈现东部高西部低的特征,因此必须合理调整西部地区的经济结构,提高资源利用效率和加强环境保护,实现可持续发展.该方法的权重取值较为客观和科学,评估结果合理,值得推广应用.     

Volatile organic compound emissions from straw-amended agricultural soils and their relations to bacterial communities: A laboratory study

A laboratory study was conducted to investigate volatile organic compound(VOC) emissions from agricultural soil amended with wheat straw and their associations with bacterial communities for a period of 66 days under non-flooded and flooded conditions. The results indicated that ethene, propene, ethanol, i-propanol, 2-butanol, acetaldehyde, acetone,2-butanone, 2-pentanone and acetophenone were the 10 most abundant VOCs, making up over 90% of the total VOCs released under the two water conditions. The mean emission of total VOCs from the amended soils under the non-flooded condition(5924 ng C/(kg·hr)) was significantly higher than that under the flooded condition(2211 ng C/(kg·hr)). One "peak emission window" appeared at days 0–44 or 4–44, and over 95% of the VOC emissions occurred during the first month under the two water conditions. Bacterial community analysis using denaturing gradient gel electrophoresis(DGGE) showed that a relative increase of Actinobacteria, Bacteroidetes, Firmicutes and γ-Proteobacteria but a relative decrease of Acidobacteria with time were observed after straw amendments under the two water conditions. Cluster analysis revealed that the soil bacterial communities changed greatly with incubation time, which was in line with the variation of the VOC emissions over the experimental period. Most of the above top 10 VOCs correlated positively with the predominant bacterial species of Bacteroidetes, Firmicutes and Verrucomicrobia but correlated negatively with the dominant bacterial species of Actinobacteria under the two water conditions. These results suggested that bacterial communities might play an important role in VOC emissions from straw-amended agricultural soils.