Chemical composition of selected seaweeds from the Indian Ocean,KwaZulu-Natal coast,South Africa

The chemical composition of three edible seaweeds (Codium capitatum, Hypnea spicifera and Sargassum elegans) and two inedible seaweeds (Halimeda cuneata and Spyridia hypnoides) from the Indian Ocean along the KwaZulu-Natal East Coast, South Africa were investigated as a function of seasonal variation. The proximate compositions of the edible seaweeds were determined. In edible seaweeds, the moisture level ranged from 85.4 to 89.5%, protein from 6.1 to 11.8%, lipids from 7.5 to 13.1% and carbohydrates from 37.8 to 71.9%. Elemental concentrations in the five studied seaweeds varied significantly with season (P < 0.05) with mean elemental concentrations (in µg g^?1, dry weight) being: Ca (29 260), Mg (6 279), Fe (1 086), Cu (145.9), Mn (48.32), As (24.29), Zn (15.65), Ni (9.83), Cr (5.78), Pb (4.84), Co (0.87) and Se (0.86). The concentrations of As were particularly high in S. elegans, ranging from 94.70 ± 6.6 µg g^?1 in winter to 65.10 ± 2.3 µg g^?1 in summer. Hierarchical cluster analysis showed similar distribution of elements in edible seaweeds which was dissimilar to that in inedible seaweeds. This study suggests that edible macro alga, C. capitatum and H. spicifera, could be potential sources of most essential nutrients and may contribute positively to the diet without posing the risk of adverse health effects due to low concentrations of toxic elements. However, due to high levels of As in S. elegans, its consumption should be moderated to reduce dietary exposure to this toxic element.     

Direct spectral analysis and determination of high content of carcinogenic bromine in bread using UV pulsed laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) was applied for the detection of carcinogenic elements like bromine in four representative brands of loaf bread samples and the measured bromine concentrations were 352, 157, 451, and 311 ppm, using Br I (827.2 nm) atomic transition line as the finger print atomic transition. Our LIBS system is equipped with a pulsed laser of wavelength 266 nm with energy 25 mJ pulse^?1, 8 ns pulse duration, 20 Hz repetition rate, and a gated ICCD camera. The LIBS system was calibrated with the standards of known concentrations in the sample (bread) matrix and such plot is linear in 20–500 ppm range. The capability of our system in terms of limit of detection and relative accuracy with respect to the standard inductively coupled plasma mass spectrometry (ICPMS) technique was evaluated and these values were 5.09 ppm and 0.01–0.05, respectively, which ensures the applicability of our system for Br trace level detection, and LIBS results are in excellent agreement with that of ICPMS results.     

国外生态补偿机制设计中的关键要素及启示

近年来,生态补偿已成为国内外学界关注的热点,各国相关实践也日益广泛深入。国外关于生态补偿的概念界定并不一致,不同国家的生态补偿实践也不尽相同,但通过考察现有相关研究和实践,可以总结和归纳出各国在生态补偿机制设计中均需考虑的一些关键要素。其中,生态补偿概念的构成要素包括外部性、条件性和自愿性,反映出生态补偿区别于其他环境保护政策工具所具有的核心特征;生态补偿效率的影响要素指向生态补偿的环境效益和成本效益,决定了生态补偿目的能否实现以及实现的程度和代价。提高环境效益的关键在于满足登记、目标锁定、额外性、联结和持续性的要求,避免泄漏、不正当激励和动机挤出效应的出现,而提高成本效益的关键则在于降低交易成本;生态补偿实施的制约要素是指机制运行的前提条件和事后保障,直接影响生态补偿最终能否真正落实和有效实施,包括制度背景例如生态系统服务提供者的财产使用权、透明度、附加目标、商业和技术支持等,以及事后的监督与评估,这也是条件性的必然要求。中国在建立健全生态补偿机制时,应当立足于本国的制度背景,同时借鉴国外先进经验,明确生态补偿的内涵和实质,从制度创新出发,将政府补偿和市场交易相融合,在生态补偿实施方案或协议的拟定中,将各项关键要素融入精密的条款设计中,明确利益相关各方的角色和责任,更好地实现生态补偿防止生态系统服务退化、促进生态系统服务恢复以及确保生态系统服务持续提供的功能,达成效益、效率和公平等价值目标。     

Development of a Concept for Non-monetary Assessment of Urban Ecosystem Services at the Site Level

Determining the performance of ecosystem services at the city or regional level cannot accurately take into account the fine differences between green or gray structures. The supply of regulating ecosystem services in, for instance, parks can differ as parks vary in their land cover composition. A comprehensive ecosystem service assessment approach also needs to reflect land use to consider the demands placed on ecosystem services, which are mostly neglected by current research yet important for urban planning. For instance, if a sealed surface is no longer used, it could be unsealed to improve ecosystem service supply. Because of these scientific shortcomings, this article argues for a conceptual framework for the non-monetary assessment of urban ecosystem services at the site scale. This paper introduces a standardized method for selecting representative sites and evaluating their supply of and demand on ecosystem services. The conceptual design is supplemented by examples of Salzburg, Austria.     

300MW汽轮发电机定子接地保护动作跳机原因分析及防范措施

某热电厂13号发电机定子接地保护动作跳闸,发电机组全停,依据电厂主设备的具体参数和配置情况,对故障录波图进行分析,检查了发电机及附属设备,并对发电机单元主要一次设备进行了试验,对机组跳闸原因进行了分析,提出了防范措施.     

Effects and mechanisms of the combined pollution of lanthanum and acid rain on the root phenotype of soybean seedlings

Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La³⁺) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La³⁺ and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La³⁺ and acid rain. The deleterious effects of the combined pollution were stronger than those of single La³⁺ or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots.     

Method of median semi-variance for the analysis of left-censored data: Comparison with other techniques using environmental data

In environmental monitoring, variables with analytically non-detected values are commonly encountered. For the statistical evaluation of these data, most of the methods that produce a less biased performance require specific computer programs. In this paper, a statistical method based on the median semi-variance (SemiV) is proposed to estimate the position and spread statistics in a dataset with single left-censoring. The performances of the SemiV method and 12 other statistical methods are evaluated using real and complete datasets. The performances of all the methods are influenced by the percentage of censored data. In general, the simple substitution and deletion methods showed biased performance, with exceptions for L/2, Inter and L/√2 methods that can be used with caution under specific conditions. In general, the SemiV method and other parametric methods showed similar performances and were less biased than other methods. The SemiV method is a simple and accurate procedure that can be used in the analysis of datasets with less than 50% of left-censored data.     

Analytical methods and validation for determining trace elements in red wines

The objective of this work is to quantify As, Hg, Cd, Ni and Pb in Portuguese red wines. First, the methods for the quantification of trace elements in red wines were validated. Several pre-treatments were compared, namely a pre-digestion process with HNO₃, a pre-oxidation step with H₂O₂, and a spiking step of wine samples with a known concentration of the trace elements analyzed. Except for As, it was determined that the quantification of the trace elements does not require a pre-digestion process with HNO₃. For all of the trace elements analyzed, a pre-oxidation step with H₂O₂ may enable an accurate quantification. The techniques chosen for the quantification of trace elements were hydride generation atomic absorption spectrometry (HGAAS) for As and Hg, electrothermal atomic absorption spectrometry (ETAAS) for Cd, and flame atomic absorption spectrometry (FAAS) for Ni and Pb. In the second stage of this work, 25 Portuguese red wines spanning all of the red wine-producing regions were analyzed for all of the five trace elements referred to above. Only Cd and Pb have shown concentrations above the limit values defined by the “Organization Internationale de la Vigne et du Vin.” The Target Hazard Quotient (THQ) equation was used to determine in which wine-producing regions that wine consumption can be a problem for public health in terms of the concentrations of the five trace elements analyzed. THQ values have indicated that for the universe of the 25 red wines analyzed no region produces wines that can pose problems for public health, when the Portuguese red wine standard consumption is considered.     

Foreword

We provide an introduction to the volume The Arctic in the Earth System perspective: the role of tipping points. The terms tipping point and tipping element are described and their role in current science, general debates, and the Arctic are elucidated. From a wider perspective, the volume focuses upon the role of humans in the Arctic component of the Earth system and in particular the envelope for human existence, the Arctic ecosystems. The Arctic climate tipping elements, the tipping elements in Arctic ecosystems and societies, and the challenges of governance and anticipation are illuminated through short summaries of eight publications that derive from the Arctic Frontiers conference in 2011 and the EU FP7 project Arctic Tipping Points. Then some ideas based upon resilience thinking are developed to show how wise system management could ease pressures on Arctic systems in order to keep them away from tipping points.     

Biphasic effects of lanthanum on Vicia faba L. seedlings under cadmium stress, implicating finite antioxidation and potential ecological risk

In the present study, lanthanum (La) as a representative REE was used to explore the mechanisms for alleviation of Cd-induced oxidative damage by extraneous La at appropriate concentrations, and to assess ecological risk of combination of Cd and La at higher concentrations in roots of Vicia faba L. seedlings. The seedlings were hydroponically cultured for 15 d under nutrient solution, 6 μmol L⁻¹ CdCl₂, and combination of 6 μmol L⁻¹ CdCl₂ and increasing concentrations of La, respectively. The results showed that the supplementation with low concentrations of exogenous La (<120 μmol L⁻¹) led to reduced contents of Cd, Ca, Cu, Zn, Mn or Fe element and increased activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) isozymes as well as heat shock protein 70 (HSP 70) production in the roots. However, the supplementation with higher La (>120 μmol L⁻¹) showed the adverse effects. The contents of Cd elevated above the single Cd treatment in the roots, accompanying with the decline of antioxidant isozyme’s activities and HSP 70, and increment of carbonylated proteins and endoprotease isozyme’s activities. The results also showed that the root growth was not only related to carbonylated proteins, but also to indole acetic acid oxidase activities. Therefore, the supplemented extraneous La contributed to biphasic effects: stimulated antioxidation at lower concentrations and pro-oxidation at higher concentrations against Cd-induced oxidative stress in the roots.