Is the availability of different nutrients a critical factor for the impact of bacteria on subterraneous carbon budgets?

Bacteria thriving in underground systems, such as karsts, adapt to use a variety of nutrients. Most of these nutrients derive from superficial processes. This study shows that bacteria are able to differentially induce carbonate precipitation or dissolution depending on the availability of nutrients for growth. Different bacterial strains isolated from caves, representing the most common components of these microbial communities, were cultured with different carbon and nitrogen sources (e.g., acetate, glucose, peptone, humic acids) and induced changes in pH were measured during growth. Carbonate can either precipitate or dissolve during bacterial growth. The induction of carbonate precipitates or their dissolution as a function of consumption of specific carbon sources revealed the existence of an active nutrient cycling process in karsts and links nutrients and environmental conditions to the existence of a highly significant carbon sink in subterraneous environments.     

Waging the struggle for healthy eating: food environments,dietary regimes and Brazil's dietary guidelines

The struggle for healthy eating is a nascent social movement that represents active resistance to the hostile food environments created by multinational food and beverage corporations. Using a political economy approach and leveraging Winson's [2013. The industrial diet: the degradation of food and the struggle for healthy eating. Vancouver: UBC Press] concepts of dietary regimes and the industrial diet, this paper will examine the strengths and limitations of Brazil's new dietary guidelines and discuss its role as a precursor to a new dietary regime that incorporates social justice and sustainability.     

Adaptation of Nitraria sphaerocarpa to wind-blown sand environments at the edge of a desert oasis

This study addresses the adaptation of Nitraria sphaervcarpa to blown sand at the edge of a desert oasis with regard to the aspects of soil seed banks, seedlings, and population. Horizontally, the total number of seeds per unit area decreased from the shrub canopy center to intershrub areas, and most seeds were found under shrub canopies. Vertically, the highest proportion of seeds was found at depths of 5-10 cm. The emergence percentage, seedling mass, and seedling height, which were significantly affected by both burial depth and seed size, were highest at the optimal burial depth of 2 cm, and decreased with increasing burial depth in each seed size-class. Although seedling mass was usually greatest for large seeds and least for small seeds at each burial depth, little difference was observed in seedling height at shallow burial depths of 0-3 cm. The population shows a patchy and discontinuous distribution pattern. Population height increases with increasing sand depth. Also the density increases with increasing depth of sand in the desert; however, there is a steady decrease when the depth of sand is more than 100 cm. This result indicates that the depth of sand that is most suitable for the growth of Nitraria sphaervcarpa is 100 cm. The size of the population is significantly correlated with the sand depth, which increases with increasing depth in the desert.     

Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

Polymerase chain reaction(PCR)was used to amplify a 600-base pair(bp)sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil(Alfisol)and Red soil(Ultisol),and three different minerals(goethite,kaolinite,montmorillonite). DNA bound on soil colloids,kaolinite,and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted,10- and 20-fold.The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected.DNA bound on goethile was amplified irrespective of whether the complex was used directly,or diluted 10- and 20-fold.The amplification of mineral-bound plasmid DNA by PCR is,therefore,markedly influenced by the type and concentration of minerals used.This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.     

中国粮食主产区耕地土壤重金属时空变化与污染源分析

土壤重金属污染威胁着农田生态系统安全和人类健康.基于2000年以来中国五大粮食主产区3 006个耕地样点的土壤重金属实测数据和20世纪80年代的土壤重金属历史数据,采用单因子指数法评估了粮食主产区耕地土壤重金属的污染现状和变化趋势,并基于地累积指数,结合区位环境污染探讨了其污染来源.结果表明,中国粮食主产区耕地土壤重金属点位超标率为21.49%,整体以轻度污染为主,其中轻度、中度和重度污染比重分别13.97%、2.50%和5.02%.四川盆地、长江中游及江淮地区、黄淮海平原、松嫩平原和三江平原的耕地点位超标率分别为43.55%、30.64%、12.22%、9.35%和1.67%,南方耕地污染重于北方.主要污染物为Cd、Ni、Cu、Zn、Hg,超标率分别为17.39%、8.41%、4.04%、2.84%、2.56%.自20世纪80年代以来,耕地土壤重金属含量呈增加趋势,整体上点位超标率增加了14.91%,其中Cd、Ni、Cu、Zn和Hg的污染比重分别增加了16.07%、4.56%、3.68%、2.24%和1.96%.除三江平原外,其他4个粮食主产区耕地土壤重金属点位超标比重增加趋势显著,且南方地区的Cd、Ni和Cu重金属超标比重变化量高于北方,而Hg和Cr增速低于北方.Cd、Hg以人为污染源为主,其他6种重金属以自然污染源为主,但Pb、Zn和Cu约有20.00%的点位受人为活动的影响.矿业、工业、污灌水是主要的污染源,除污灌水来源北方重于南方外,其余污染来源均是南方污染重于北方,污染物种类也多于北方.     

双酚S和双酚F在水环境中的分布、毒理效应及其生态风险研究进展

双酚S(BPS)和双酚F(BPF)作为双酚A(BPA)的替代品在工业中被广泛使用。近年来BPS和BPF在水环境中不断检出,因其难降解、易蓄积,可能会对水生态系统和人体健康造成不利影响。因此对BPS和BPF在水、沉积物等水环境介质中污染状况进行综述,发现BPS和BPF的含量有日益升高的趋势,甚至在某些水体中的浓度超过BPA。然后,从急性毒性、内分泌干扰效应、发育毒性等3个方面,阐述了它们对水生生物产生的毒理效应。并且基于水环境介质中的检出浓度和实验室毒理数据,对水体和沉积物中BPS和BPF的生态风险进行评估,发现沉积物中的风险要高于水体。最后对目前研究局限以及未来的研究方向进行了探讨和展望。     

Human appropriation of net primary production (HANPP) in Nova Scotia,Canada

Photosynthetically fixed energy from the sun, in the form of net primary production, ultimately supports the majority of life on earth. Given the importance of this energy source, we calculate the human appropriation of net primary production (HANPP) for the province of Nova Scotia, Canada. We find that over 25% of potentially available production is appropriated by humans through harvest (forestry and agriculture) and land cover change. The level of appropriation in Nova Scotia is close to the global average, when methodological differences between studies are taken into account, but substantially less than in Austria and India where detailed surveys have also been conducted. Furthermore, HANPP is not distributed evenly throughout the province, but is instead concentrated in the north-central counties, where appropriation reaches 50%. We discuss the implications of these results, and the novel method used to obtain them, in the context of biophysical assessment and the species-energy hypothesis.     

Development of the PRCQ: A measure of perceived restorative characteristics of zoo attractions

This study describes the development of the Perceived Restorative Characteristics Questionnaire (PRCQ), a measure of perceived restorative characteristics of zoo attractions. The questionnaire was administered in two zoo attractions. The hypothesized five factor structure of the PRCQ, and relations between perceived restorative characteristics and experienced pleasure in and preference for the attractions were examined. In Study 1, 137 visitors of a Dutch zoo evaluated perceived restorative characteristics of a butterfly garden; In Study 2, 158 visitors evaluated those of a baboon attraction. In Study 1 three factors emerged (fascination, escape and coherence); In Study 2 four factors could be distinguished (fascination, novelty, escape, coherence). Compatibility did not appear as a separate factoring either study. Perceived fascination and escape were significant predictors of experienced pleasure and preference in both attractions. The implications of the findings are discussed.     

一种多参数小型化飞机结构腐蚀环境监测技术

目的研究腐蚀与环境条件之间的关系,提出一种用于飞机腐蚀环境监测的小型化监测节点的实现方法。方法针对影响腐蚀的4个关键环境参数(温度、相对湿度、湿润时间和氯离子浓度),研究其传感方法并研发选型相应传感器。在此基础上设计基于MSP430处理器的多参数飞机腐蚀环境监测节点。结果通过实验验证了节点中的温湿度传感器、湿润时间传感器和电化学传感器的适用性,能够完成对环境参数的的测量。结论设计的节点满足机载装置小型化、轻量化的要求,可以实现在线的腐蚀环境监测,从而保障飞行安全。     

Modeling the vegetation-atmosphere carbon dioxide and water vapor interactions along a controlled CO2 gradient

Ecosystem functioning is intimately linked to its physical environment by complex two-way interactions. These two-way interactions arise because vegetation both responds to the external environment and actively regulates its micro-environment. By altering stomatal aperture, and therefore the transpiration rate, plants modify soil moisture and atmospheric humidity and these same physical variables, in return, modify stomatal conductance. Relationships between biotic and abiotic components are particularly strong in closed, managed environments such as greenhouses and growth chambers, which are used extensively to investigate ecosystem responses to climatic drivers. Model-assisted designs that account for the physiological dynamics governing two-way interactions between biotic and abiotic components are absent from many ecological studies. Here, a general model of the vegetation-atmosphere system in closed environments is proposed. The model accounts for the linked carbon-water physiology, the turbulent transport processes, and the energy and radiative transfer within the vegetation. Leaf gas exchange is modeled using a carbon gain optimization approach that is coupled to leaf energy balance. The turbulent transport within the canopy is modeled in two-dimensions using first-order closure principles. The model is applied to the Lysimeter CO₂ Gradient (LYCOG) facility, wherein a continuous gradient of atmospheric CO₂ is maintained on grassland assemblages using an elongated chamber where the micro-climate is regulated by variation in air flow rates. The model is employed to investigate how species composition, climatic conditions, and the imposed air flow rate affect the CO₂ concentration gradient within the LYCOG and the canopy micro-climate. The sensitivity of the model to key physiological and climatic parameters allows it to be used not only to manage current experiments, but also to formulate novel ecological hypotheses (e.g., by modeling climatic regimes not currently employed in LYCOG) and suggest alternative experimental designs and operational strategies for such facilities.