Morphometry and sedimentation as regulating factors for nutrient recycling and trophic state in coastal waters

The aim of this work is to quantify the importance of morphometry and sedimentation/resuspension on nutrient recycling and trophic characteristics in coastal waters. Extensive field work has been carried out in 23 coastal areas in the Swedish and Finnish part of the Baltic Proper. Sediment traps were deployed for two one-week periods in all areas. On average, 56% of the total sedimentation in sediment traps 3 m below the water surface (SedS) and 62% of the total sedimentation on sediment traps 1 m above the bottom (SedB) was resuspended material. Coastal morphometric parameters, surface water retention time and bottom dynamic conditions were determined for all areas. There is a marked relationship between SedS and inorganic-N concentration in the surface water. The relationship was improved significantly by using sedimentation of the resuspended fraction at 3 m water depth (SedR) instead of SedS.This led to the hypothesis that increased concentration of inorganic nitrogen in the surface water results from increased mineralisation of resuspended organic particles. A model describing SedS is presented where inorganic nitrogen concentration, the water surface area and the surface water retention time can explain 82% of the variation in SedS. In another model inorganic nitrogen and water surface area can explain as much as 93% of the variation in SedR.These results emphasise the importance of resuspension for nutrient recycling and trophic state in coastal waters. The importance of coastal morphometry and surface water retention time on total sedimentation and nutrient recycling makes it possible to classify coastal areas in terms of potential nutrient recycling capacity/trophic state from these simple sensitivity parameters.     

Flexibility in CO2 — Fixation Pathway of a Highland Kalanchoë, Kalanchoë petitiana A. Rich.

Photosynthetic flexibility and water use efficiency of Kalanchoë petitiana A. Rich., a facultative CAM plant endemic to the highlands of Ethiopia, were investigated to determine the physiological determinants for the ecological success of the plant. Both field measurements of δ¹³C and greenhouse gas exchange studies showed a shift from C₃ photosynthesis to CAM as leaves aged or at the onset of water stress. Recycling of CO₂ was observed in developing leaves without concomitant net CO₂ uptake. Accumulation of malate was positively correlated with increased cell sap osmolality and improved daily water use efficiency. The importance of flexibility in carbon uptake pathway and of recycling CO₂ for the ecological success of the plant is discussed.     

Vertical stratification of °13C values in closed natural and plantation forests in the Luquillo mountains,Puerto Rico

Summary The variability of ¹³C values was measured in leaf, stem and root tissues of several tree species growing in closed natural and plantation forests in the Luquillo mountains of Puerto Rico. Results confirm a significant decrease of ¹³C values from the tree canopy to the forest floor. The values measured in understory plants growing in gaps were not significantly different from the average for plants growing under the forest shade. Seedling leaf values tended to be more positive than those of saplings, probably reflecting the contribution of organic matter from the mother tree. Photosynthetic independence on the forest floor results in a reduction in °¹³C value. Stem and root tissue values of seedlings and saplings were less negative than those of the leaves of the same plants. It is suggested that this difference results from the slower change in isotopic composition experienced by the woody tissue, as the seedlings become photosynthetically independent in the forest floor.     

From Cradle to Grave: Extended Producer Responsibility for Household Hazardous Wastes in British Columbia

Household hazardous wastes (HHWs), the discarded pesticides, solvents, paints, lubricating oil, and similar products common to residences throughout the industrial world, create problems for governments charged with managing solid waste. When disposed of improperly in landfills or incinerators or if dumped illegally, HHW may contribute to soil and water contamination. A most common management tool for HHW is a special collection effort that segregates HHW from normal trash and disposes of it in an approved manner, all at a higher cost to the governmental jurisdiction. The Canadian province of British Columbia (BC) has undertaken a different approach, based on the use of extended producer responsibility (EPR). BC's efforts began in 1992 with adoption of a regulation on used lubricating oil (lube oil). More than 40 million liters (L) of used lube oil have been collected annually through the EPR system established under this regulation. A regulation establishing producer responsibility for postconsumer paints followed in 1994. BC enacted an additional regulation establishing EPR in 1997 for solvents/flammable liquids, domestic pesticides, gasoline, and pharmaceuticals. As a result of the application of EPR to HHW, local government costs for managing HHW and the amount of HHW identified in municipal waste have declined. Although the regulations appear to have mixed success in prompting consumers to avoid products that result in HHW, there are indications that they may be more effective than conventional management efforts. Based on BC's experience with EPR, key factors for successful implementation include maintaining flexibility in program design, creating viable funding alternatives, aggressive enforcement to provide a level playing field, and adopting policies that maximize diversion of HHW from landfills, while minimizing waste generation, setting targets for reuse and recycling, promoting consumer awareness and convenience, involving local government jurisdictions, and monitoring outcomes.     

Catecholamine detection using enzymatic amplification

Different amplification sensors based on the substrate recycling principle were investigated with respect to their applicability to catecholamine detection. In the bioelectrocatalytic approach, glassy carbon electrodes were modified by laccase or a PQQ-dependent glucose dehydrogenase. Substrate recycling occurs and the detection limit is in the lower nanomolar concentration range (e.g. 10 nM dopamine and 1 nM noradrenaline for the laccase- and glucose dehydrogenase-modified electrodes, respectively). Combinations of glucose dehydrogenase with laccase or tyrosinase were investigated as bienzymatic probes. Among the systems we studied, the laccase/glucose dehydrogenase sensor is the most sensitive (detection limit: 0·5 nM adrenaline). The selectivities of the different sensor systems are discussed. Application of the laccase/glucose dehydrogenase electrode in different media (i.e. brain homogenate, heart effluate) was successfully shown. For samples with high concentrations of interfering substances (uric and ascorbic acid), the interferences can be effectively removed using enzymatic methods.     

Microelectrode arrays and application to biosensing devices

An electrochemical microanalytical system consisting of a microelectrode array, a micromachined flow-through assembly, and a multichannel potentiostat were constructed for highly sensitive biosensing. Thin-film platinum microelectrode arrays consisting of four interdigitated microelectrodes (IDAs), which are spaced in the sub-micrometer range, were fabricated using silicon technology. On top of this chip, a micromachined flow-through cell was mounted. Using a home made miniaturized multipotentiostat, amperometric measurements of the individual electrodes at different and changing potentials, respective to a single reference electrode, were performed simultaneously. The signal generation, signal processing and the analytical system were controlled by a computer (PC type) and special software. An improved sensor sensitivity was achieved by multielectrode detection and averaging of the IDA responses.

By applying both the oxidation and reduction potentials of reversible redox molecules to pairs of the interdigitated electrodes, an increased current generation can be observed. Thus the steady state current of mediators such as benzoquinone can be amplified by a factor of 30 compared with conventional electrodes. This measuring principle was applied to determine of the activity of hydrolases by detecting the enzyme generated p-aminophenol in the nanomolar range. By combining both, the averaging and the recycling procedures, the detection limit of amperometric biosensing devices may be lowered by about one and a half orders of magnitude.     

基于能值分析法的矿区循环经济系统生态效率分析

从系统的角度界定了循环经济和矿区循环经济的内涵,提出了煤炭矿区循环经济系统的基本框架,并以能值分析法为基础构建了矿区循环经济系统生态效率评价指标体系与方法。运用所构建的评价指标体系与方法对山东某矿区进行了研究,得出该矿区循环经济系统2007—2011年5年间的能值效率变化趋势图和生态效率指数趋势图,研究结果与该矿区的实际发展趋势基本一致。表明运用能值分析法所建立的评价指标体系具有较强的有效性,并且对煤炭矿区发展循环经济、提高生态效率具有重要指导意义和参考价值。     

Evolutionary genetics of resistance and tolerance to natural herbivory in Arabidopsis thaliana

Resistance and tolerance are widely viewed as two alternative adaptive responses to herbivory. However, the traits underlying resistance and tolerance remain largely unknown, as does the genetic architecture of herbivory responses and the prevalence of genetic trade-offs. To address these issues, we measured resistance and tolerance to natural apical meristem damage (AMD) by rabbits in a large field experiment with recombinant inbred lines (RILs) of Arabidopsis thaliana (developed from a cross between the Columbia x Landsberg erecta ecotypes). We also measured phenological and morphological traits hypothesized to underlie resistance and tolerance to AMD. Recombinant inbred lines differed significantly in resistance (the proportion of replicates within an RIL that resisted herbivory), and early flowering plants with tall apical inflorescences were more likely to experience damage. Tolerance (the difference in fitness between the damaged and undamaged states), also differed significantly among RILs, with some lines overcompensating for damage and producing more fruit in the damaged than undamaged state. Plastic increases in basal branch number, basal branch height, and senescence date in response to damage were all associated with greater tolerance. There was no evidence for a genetic trade-off between resistance and tolerance, an observation consistent with the underlying differences in associated morphological and phenological characters. Selection gradient analysis detected no evidence for direct selection on either resistance or tolerance in this experiment. However, a statistical model indicates that the pattern of selection on resistance depends strongly on the mean level of tolerance, and selection on tolerance depends strongly on the mean level of resistance. These observations are consistent with the hypothesis that selection may act to maintain resistance and tolerance at intermediate levels in spatially or temporally varying environments or those with varying herbivore populations.     

A Material Flow‐based Approach to Enhance Resource Efficiency in Production and Recycling Networks

Resource and energy efficiency are key strategies for production and recycling networks. They can contribute to more sustainable industrial production and can help cope with challenges such as competition, rising resource and energy prices, greenhouse gas emissions reduction, and scarce and expensive landfill space. In pursuit of these objectives, further enhancements of single processes are often technologically sophisticated and expensive due to past achievements that have brought the processes closer to technical optima. Nevertheless, the potential for network‐wide advancements may exist. Methods are required to identify and assess the potential for promising resource and energy efficiency measures from technical, economic, and ecological perspectives. This article presents an approach for a material flow‐based techno‐economic as well as ecological analysis and assessment of resource efficiency measures in production and recycling networks. Based on thermodynamic process models of different production and recycling processes, a material and energy flow model of interlinked production and recycling processes on the level of chemical compounds is developed. The model can be used to improve network‐wide resource efficiency by analyzing and assessing measures in scenario and sensitivity analyses. A necessary condition for overcoming technical and economic barriers for implementing such measures can be fulfilled by identifying strategies that appear technologically feasible and economically and ecologically favorable. An exemplary application to a production and recycling network of the German steel and zinc industry is presented. From a methodological point of view, the approach shows one way of introducing thermodynamics and further technological aspects into industrial planning and assessment.