Bacterial Degradation of Vegetable Oils

Following initial experiments presented elsewhere (2IOPS), the bacterial degradation of two vegetable oils was investigated in some detail. the number of aerobic and anaerobic heterotrophic bacteria, oil degrading and sulphate reducing bacteria were quantified during simulated spills on a salt marsh. the sediment fatty acid composition was also studied using GC-MS analysis. Degradation of linseed and sunflower oils was concomitant with an increase in the numbers of aerobic and anaerobic bacteria. Fatty acids analysis revealed preferential degradation of the principal components of the oils (18:3ω3 for linseed oil and 18:2ω6 for sunflower oil). the presence of several isomers of the usual polyunsaturated fatty acids was also detected. the identification of some of these new fatty acids has been carried out. Possible pathways of degradation of these vegetable oils are suggested.     

金属基工程纳米颗粒与水生高等植物的相互作用：研究现状综述

如今释放到水体环境中的工程纳米颗粒(ENP)数量与日俱增。为确保生态健康,需要进行相关的风险评估。本文综述了金属基ENP与水生高等植物之间的相互作用,找到了信息缺口并提出对未来研究的构想,为在该领域内的进一步探索提供了基础。本文讨论集中在以下3点：1. ENP的生物利用性;2. 生物对ENP的摄取、消化、转移以及生物累积;3. ENP对水生高等植物的毒性效果。由于ENP自身特性所带来的影响不明确以及水质状况记载情况不佳,ENP的摄取及相关动力学方面存在着很大的信息差距。分解似乎是驱动ENP生物累积的一种关键机制,然而纳米颗粒却常常被一些有着极少内化作用的植物的表面所吸收。然而,关于ENP在植物内的内化作用鲜有记载,因此纳米颗粒的内化作用对于生物累积及毒性的影响尚不明确。即使金属基ENP的纳米毒性已被报道,分解依然被认为是其毒性的主要机制。为推动该领域内的研究发展,未来的研究需结合ENP自身特性的影响、水体的理化参数以及它们之间的相互作用。相互作用对于ENP的生物利用性和对水生高等植物健康的风险都有重要影响。为了快速追踪类似数据的产生,我们建议测试方案趋向一致化。
精选自Melusi Thwala, Stephen J. Klaine, Ndeke Musee. Interactions of metal-based engineered nanoparticles with aquatic higher plants: a review of the state of current knowledge. Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1677–1694, July 2016. DOI: 10.1002/etc.3364
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3364/full
     

Explaining the fragmentation in the Brazilian Amazonian forest

Although vast literature exists on the drivers of tropical deforestation and its ecological consequences, less is known about how patterns of forest fragmentation emerge in the first place. The purpose of this paper is to address this issue for the Brazilian portion of the Amazon basin by analyzing the social processes generative of five specific patterns, including rectangular, fishbone, radial, dendritic, and what we refer to as ‘the stem of the rose.’ We argue that forest fragmentation patterns in the Brazilian Amazon are largely determined by the types and arrival times of the agents who engage in land clearing. We also argue that the patterns manifest in the landscape by virtue of road construction and agricultural property formation, which often occur in tandem. We conclude by placing our discussion within legal and institutional contexts, and observe that fragmentation stemming from formal colonization projects is more consistent with biodiversity conservation than that associated with a laissez-faire occupation. However, erosive impacts may be greater in topographically sensitive areas.     

Functional traits and the growth-mortality trade-off in tropical trees

A trade-off between growth and mortality rates characterizes tree species in closed canopy forests. This trade-off is maintained by inherent differences among species and spatial variation in light availability caused by canopy-opening disturbances. We evaluated conditions under which the trade-off is expressed and relationships with four key functional traits for 103 tree species from Barro Colorado Island, Panama. The trade-off is strongest for saplings for growth rates of the fastest growing individuals and mortality rates of the slowest growing individuals (r2 = 0.69), intermediate for saplings for average growth rates and overall mortality rates (r2 = 0.46), and much weaker for large trees (r2 < or = 0.10). This parallels likely levels of spatial variation in light availability, which is greatest for fast- vs. slow-growing saplings and least for large trees with foliage in the forest canopy. Inherent attributes of species contributing to the trade-off include abilities to disperse, acquire resources, grow rapidly, and tolerate shade and other stresses. There is growing interest in the possibility that functional traits might provide insight into such ecological differences and a growing consensus that seed mass (SM), leaf mass per area (LMA), wood density (WD), and maximum height (H(max)) are key traits among forest trees. Seed mass, LMA, WD, and H(max) are predicted to be small for light-demanding species with rapid growth and mortality and large for shade-tolerant species with slow growth and mortality. Six of these trait-demographic rate predictions were realized for saplings; however, with the exception of WD, the relationships were weak (r2 < 0.1 for three and r2 < 0.2 for five of the six remaining relationships). The four traits together explained 43-44% of interspecific variation in species positions on the growth-mortality trade-off; however, WD alone accounted for > 80% of the explained variation and, after WD was included, LMA and H(max) made insignificant contributions. Virtually the full range of values of SM, LMA, and H(max) occurred at all positions on the growth-mortality trade-off. Although WD provides a promising start, a successful trait-based ecology of tropical forest trees will require consideration of additional traits.     

Spatial distribution of lead concentrations in urban surface soils of New Orleans, Louisiana USA

Immediately following hurricane Katrina concern was raised over the environmental impact of floodwaters on the city of New Orleans, especially in regard to human health. Several studies were conducted to determine the actual contaminant distribution throughout the city and surrounding wetlands by analyzing soil, sediment, and water for a variety of contaminants including organics, inorganics, and biologics. Preliminary investigations by The Institute of Environmental and Human Health at Texas Tech University concluded that soils and sediments contained pesticides, semi-volatiles, and metals, specifically arsenic, iron, and lead, at concentrations that could pose a significant risk to human health. Additional studies on New Orleans floodwaters revealed similar constituents as well as compounds commonly found in gasoline. More recently, it has been revealed that lead (Pb), arsenic, and vanadium are found intermittently throughout the city at concentrations greater than the human health soil screening levels (HHSSLs) of 400, 22 (non-cancer endpoint) and 390 μg/g, respectively. Of these, Pb appears to present the greatest exposure hazard to humans as a result of its extensive distribution in city soils. In this study, we spatially evaluated Pb concentrations across greater New Orleans surface soils. We established 128 sampling sites throughout New Orleans at approximately half-mile intervals. A soil sample was collected at each site and analyzed for Pb by ICP-AES. Soils from 19 (15%) of the sites had Pb concentrations exceeding the HHSSL threshold of 400 μg/g. It was determined that the highest concentrations of Pb were found in the south and west portions of the city. Pb concentrations found throughout New Orleans in this study were then incorporated into a geographic information system to create a spatial distribution model that can be further used to predict Pb exposure to humans in the city.     

Patterns of Genetic Diversity in Remaining Giant Panda Populations

Abstract: The giant panda ( Ailuropoda melanoleuca ) is among the more familiar symbols of species conservation. The protection of giant panda populations has been aided recently by the establishment of more and better-managed reserves in existing panda habitat located in six mountain ranges in western China. These remaining populations are becoming increasingly isolated from one another, however, leading to the concern that historic patterns of gene flow will be disrupted and that reduced population sizes will lead to diminished genetic variability. We analyzed four categories of molecular genetic markers (mtDNA restriction-fragment-length polymorphisms [RFLP], mtDNA control region sequences, nuclear multilocus DNA fingerprints, and microsatellite size variation) in giant pandas from three mountain populations (Qionglai, Minshan, and Qinling) to assess current levels of genetic diversity and to detect evidence of historic population subdivisions. The three populations had moderate levels of genetic diversity compared with similarly studied carnivores for all four gene measures, with a slight but consistent reduction in variability apparent in the smaller Qinling population. That population also showed significant differentiation consistent with its isolation since historic times. From a strictly genetic perspective, the giant panda species and the three populations look promising insofar as they have retained a large amount of genetic diversity in each population, although evidence of recent population reduction—likely from habitat loss—is apparent. Ecological management to increase habitat, population expansion, and gene flow would seem an effective strategy to stabilize the decline of this endangered species.     

Getting the Scale Right: A Comparison of Analytical Methods for Vulnerability Assessment and Household-level Targeting

This paper introduces broad concepts of vulnerability, food security and famine. It argues that the concepts and theories driving development and implementation of vulnerability assessment tools are related to their utility. The review concludes that socio-geographic scale is a key issue, and challenge. It analyses three vulnerability assessment (VA) methods, using Ethiopia as a case study. Facing the challenges of vulnerability assessment and early warning requires providing accurate information at the required scale, useful for multiple decision-makers within realistic institutional capacities.     

Characterization of Semi-refined Carrageenan-Based Film for Primary Food Packaging Purposes

Carrageenan-based films demonstrate good performance, the raw materials for their production are abundant in nature and can be sustainably sourced from seaweeds. Similar to other naturally-derived biopolymers, however, carrageenans are relatively expensive to purify and form into useful materials. In order to potentially lower the production costs compared to pure carrageenan, semi-refined carrageenan (SRC) plasticized with 0–50% (w/w) glycerol was investigated using a solution casting method. The film color and opacity increased along with the moisture content, whereas the water vapor permeability decreased with increasing levels of glycerol. The tensile properties of the SRC films improved significantly, particularly at glycerol additions greater than 30% (w/w). Moreover, the addition of glycerol improved the thermal stability and altered the surface morphology of the films. In general, the properties of the SRC films were comparable with refined carrageenan films suggesting that SRC has potential to be furthered developed into more cost effective primary food packaging materials.