Predation and aggressiveness in host plant protection: a generalization using ants from the genus Azteca

In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers' predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.     

HCH residues in point-source contaminated samples of the Teltow Canal in Berlin,Germany

Contaminated groundwater and a riverine sediment core heavily affected by the same industrial point source were analysed for hexachlorocyclohexanes (HCH) and its degradation products. A detailed quantification by GC/MS revealed contamination levels up to 730 μg/L and 396 ng/g in sum for the water and sediment samples, respectively. The isomer pattern differed significantly in both compartments. The ground water samples were depleted in γ-HCH, whereas a significant loss of α-HCH was evident in the sediments as compared to the technical composition. The data obtained revealed interesting insights into the transformation behaviour and fate of HCH mixtures in anaerobic environmental compartments. In the affected groundwater system an ongoing microbial degradation was pointed out by the identification of indicative anaerobic metabolites. On the contrary in the sedimentary system a high environmental stability or rather a hindered degradation was observed as indicated by unaltered concentration levels as compared to production rates as well as by the absence of metabolites. Interestingly, the environmental fate of HCH in subaquatic sediments as well as in anaerobic ground water differs highly in contrast to the behaviour in anaerobic soil or surface water systems. Further on, it has to be stated, that the knowledge about the long-term behaviour of HCH residues in sedimentary material under anaerobic conditions is rather limited so far.     

Effects of Coffee Management on Deforestation Rates and Forest Integrity

Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest‐agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973–2010) across elevations in 2 forest‐agriculture mosaic landscapes (1100 km² around Bonga and 3000 km² in Goma‐Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee‐growing elevations compared with at higher elevations (?10/20% vs. ?40/50% comparing relative rates at 1800 m asl and 2300–2500 m asl, respectively). Within the coffee‐growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest‐specialist species. Even if the presence of coffee slows down the conversion of forest to annual‐crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques     

Community Structure and Quality After 10 Years in Two Central Ohio Mitigation Bank Wetlands

We evaluate two 10-year-old mitigation bank wetlands in central Ohio, one created and one with restored and enhanced components, by analysis of vegetation characteristics and by comparison of the year-10 vegetation and macroinvertebrate communities with reference wetlands. To assess different measures of wetland development, we compare the prevalence of native hydrophytes with an index of floristic quality and we evaluate the predictability of these parameters in year 10, given 5 years of data. Results show that the mitigation wetlands in this study meet vegetation performance criteria of native hydrophyte establishment by year 5 and maintain these characteristics through year 10. Species richness and floristic quality, as well as vegetative similarity with reference wetlands, differ among mitigation wetlands in year 1 and also in their rate of change during the first 10 years. The prevalence of native hydrophytes is reasonably predictable by year 10, but 5 years of monitoring is not sufficient to predict future trends of floristic quality in either the created or restored wetland. By year 10, macroinvertebrate taxa richness does not statistically differ among these wetlands, but mitigation wetlands differ from reference sites by tolerance index and by trophic guild dominance. The created wetland herbivore biomass is significantly smaller than its reference, whereas detritivore biomass is significantly greater in the created wetland and smaller in the restored wetland as compared with respective reference wetlands. These analyses illustrate differences in measures of wetland performance and contrast the monitoring duration necessary for legal compliance with the duration required for development of more complex indicators of ecosystem integrity.     

Performance of some biotic indices in the real variable world: A case study at different spatial scales in North-Western Mediterranean Sea

The aim of this study was to analyse the variability of four different benthic biotic indices (AMBI, BENTIX, H′, M-AMBI) in two marine coastal areas of the North-Western Mediterranean Sea. In each coastal area, 36 replicates were randomly selected according to a hierarchical sampling design, which allowed estimating the variance components of the indices associated with four different spatial scales (ranging from metres to kilometres). All the analyses were performed at two different sampling periods in order to evaluate if the observed trends were consistent over the time. The variance components of the four indices revealed complex trends and different patterns in the two sampling periods. These results highlighted that independently from the employed index, a rigorous and appropriate sampling design taking into account different scales should always be used in order to avoid erroneous classifications and to develop effective monitoring programs.     

Fate of CL-20 in sandy soils: degradation products as potential markers of natural attenuation

Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH₂N-C(N-NO₂)-CHN-CHO or its isomer N(NO₂)CH-CHN-CO-CHNH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil.     

Evaluation of pressurized liquid extraction for the analysis of four pesticides in unpolished rice

The aim of to evaluate efficiency of this study was extraction pressurized liquid extraction (PLE) for the analysis of four pesticides, fthalide, etofenprox, fenitrothion, and isoprothiolane, in unpolished rice by comparing with homogenization as a reference technique. The concentrations of four selected pesticides obtained by PLE with acetonitrile at 130°C for 10 min × 2 cycles were comparable to those by homogenization with water-soaking. The repeatability of the analysis, represented as relative standard deviations (RSDs), were 1.4–3.6% (n = 3) for PLE at 130°C and 1.2–3.8% (n = 3) for homogenization with water-soaking. Recovery yields of surrogates were 75–88% and 87–109% for PLE at 130°C and homogenization with water-soaking, respectively, and these were satisfactory according to the method of positive list. This study suggested that PLE can be applied for the analysis of selected four pesticides in unpolished rice as well as homogenization with water-soaking.     

水环境中镍毒性的机制研究：有害结局路径(AOP)分析

目前对镍(Ni)生态风险评估和水质法规采用了基于机制的预测工具,如生物配体模型(BLMs)。然而,尽管有许多具体细致的研究,Ni对水生生物毒性的精确机制仍然难以确定。对Ni行为机制的不确定性导致了大家在一些管理设置中应用像BLM这样的工具时,有所顾虑。为了解决这一认知差距,作者使用了有害结局路径(AOP)分析,也是第一个用于金属的AOP分析,来确定Ni毒性的多种潜在机制以及它们与淡水水生生物的相互作用。在金属的分子起始事件(molecular initiating events)在分类群中可能存在的前提下,在许多不同种水生和陆生生物数据的基础上,考虑建立一种潜在的行为机制。通过分析,作者识别了Ni可能对水生生物产生毒性的5个潜在的分子起始事件：Ca²⁺体内平衡的破坏,Mg²⁺体内平衡的破坏,Fe²⁺/³⁺体内平衡的破坏,活性氧类物质引起的氧化损伤,以及呼吸上皮细胞的过敏反应。在生物组织的器官水平,这5个潜在的分子起始事件会分解成3个可能的途径：支持外骨骼、外壳和骨骼生长的Ca²⁺减少;呼吸受损;细胞毒性和肿瘤形成。在整个生物体的水平,器官水平的反应将可能导致生长、繁殖的降低和/或能量代谢的改变,并且在每个通路之间有几个潜在的反馈回路。总体来说,目前的AOP分析可指导Ni的毒性机制研究,并为其他金属开发AOPs提供了有效的参考。
精选自Brix, K. V., Schlekat, C. E. and Garman, E. R. (2017), The mechanisms of nickel toxicity in aquatic environments: An adverse outcome pathway analysis. Environmental Toxicology and Chemistry, 36: 1128–1137. doi: 10.1002/etc.3706
详情请见http://onlinelibrary.wiley.com/wol1/doi/10.1002/etc.3706/full
     

钢铁企业含铁尘泥处理与利用工艺

介绍钢铁企业含铁尘泥的处理、利用工艺及其特点,提出含铁尘泥利用应采取必要的均质化和除杂工艺,并尽可能缩短其处理流程,发挥含铁尘泥的最大利用价值。