Impact of ocean acidification on marine ecosystems: educational challenges and innovations

Population growth and social/technological developments have resulted in the buildup of carbon dioxide (CO₂) in the atmosphere and oceans to the extent that we now see changes in the earth’s climate and ocean chemistry. Ocean acidification is one consequence of these changes, and it is known with certainty that it will continue to increase as we emit more CO₂ into the atmosphere. Ocean acidification is a global issue likely to impact marine organisms, food webs and ecosystems and to be most severely experienced by the people who depend on the goods and services the ocean provides at regional and local levels. However, research is in its infancy and the available data on biological impacts are complex (e.g., species-specific response). Educating future generations on the certainties and uncertainties of the emerging science of ocean acidification and its complex consequences for marine species and ecosystems can provide insights that will help assessing the need to mitigate and/or adapt to future global change. This article aims to present different educational approaches, the different material available and highlight the future challenges of ocean acidification education for both educators and marine biologists.     

Bewertungsansatz von Umweltmonitoring-Informationssystemen in Ballungsräumen

Comprehensive data on environmental monitoring programs concerned with air pollutants like ozone (O₃), nitrogen dioxide (NO₂), nitrogen oxide (NO), carbon dioxide (CO₂) und carbon monoxide (CO), and occassionally suspended dust, benzene and other environmental chemicals, are available on the free Internet. As different monitoring information systems exist in most states or big cities of the Federal Republic of Germany, a comparison of these systems with their pros and cons is of great interest to the public. Environmental air pollutant monitoring systems in 16 states of Germany are listed and evaluated by applying 5 evaluation criteria for the differentiation of these systems. Different data-analysis methods will be applied, the Hasse diagram technique, a method derived from discrete mathematics and the partially Ordered Scalogram Analysis with Coordinates (POSAC) method, a multivariate statistical approach. The important objects, the so-called maximal or minimal objects, are detected in both methods. The Internet-based environmental monitoring systems of the states of Berlin, Bremen, Saxony-Anhalt, Baden-Wurttemberg are rated good in the evaluation approaches, whereas the information systems of the states of Brandenburg, North Rhine-Westphalia, Saxony received a rather poor ranking. The attributes of DA, way of data presentation on the Internet, and ME, type and length of measurements, were pointed out in the data-analysis methods. Multivariate explorative statistical methods offer a comprehensive tool for the graphical analysis of data-matrices. The ranking of objects is given in an effective and graphically comprehensible manner using the Hasse diagram technique. The choice and preference of the methods is problem-driven. A combination of these different methods is envisaged in the authors’ future research.     

Removal of chromium(VI) by ZnCl2 activated coir pith carbon

The adsorption of chromium(VI) onto ZnCl₂ activated carbon developed from coir pith was investigated to assess the possible use of this adsorbent. The influence of contact time, adsorbent dose, Cr(VI) concentration, pH and temperature were investigated. The two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption capacity (Q ₀) was found to be 120.5?mg Cr(VI) per g of the adsorbent. The adsorption followed the second-order kinetics and was found to be maximum at pH 2.0. The pH effect and the desorption studies showed that ion exchange mechanism might be involved in the adsorption process. The effects of foreign ions such as chloride, sulphate, phosphate, selenite, molybdate, nitrate and perchlorate on the removal of Cr(VI) have been investigated. The removal of Cr(VI) from synthetic ground water was also tested. The results show that ZnCl₂ activated coir pith carbon is effective for the removal of Cr(VI) from water.     

Analyzing the effectiveness of international environmental policies: The case of the Kyoto Protocol

We study the effectiveness of emission targets under the Kyoto Protocol with respect to reducing CO₂ emissions. Using country-level and US state-level panel data and employing the synthetic control method, we find very little evidence for an emission reduction effect for the major emitters among the Annex B countries with binding emission targets. More generally, we also show that evaluating the effectiveness of international environmental policies at the country level comes with a number of empirical challenges that may invalidate findings based on more traditional panel data approaches.     

Larvae of the pteropod Cavolinia inflexa exposed to aragonite undersaturation are viable but shell-less

Larvae of the Mediterranean pteropod Cavolinia inflexa were maintained at controlled pH_T values of 8.1, 7.82 and 7.51, equivalent, respectively, to pCO₂ levels of 380, 857 and 1,713 μatm. At pH_T 7.82, larvae exhibited malformations and lower shell growth, compared to the control condition. At pH_T 7.51, the larvae did not make shells but were viable and showed a normal development. However, smaller shells or no shells will have both ecological (food web) and biogeochemical (export of carbon and carbonate) consequences. These results suggest that pteropod larvae, as well as the species dependent upon them or upon adults as a food resource, might be significantly impacted by ocean acidification.     

Graphene and its derivatives: synthesis,modifications, and applications in wastewater treatment

Graphene was discovered in 2004 and has attracted intensive interests because of its unique mechanical, electric, thermal, optical, and structural properties, which makes graphene a potential candidate for various applications. Graphene is being used as a composite or filler material with metals, metal oxides, and polymers for potential advanced applications in solar cells, lithium-ion batteries, photocatalysis and sensing. These applications depend upon the distinctive properties of graphene, which in turn depend on the adopted synthetic approach. This article reviews the recent developments in synthesis of graphene and related composite materials. The synthesis of graphene through exfoliation, epitaxial growth and direct growth via carbon source, and modification approaches by covalent and noncovalent methodologies are discussed. Graphene-based metal and metal oxide composites for the purification of wastewater using photolytic process are also presented.     

Assessing the carbon balance of circumpolar Arctic tundra using remote sensing and process modeling.

This paper reviews the current status of using remote sensing and process-based modeling approaches to assess the contemporary and future circumpolar carbon balance of Arctic tundra, including the exchange of both carbon dioxide and methane with the atmosphere. Analyses based on remote sensing approaches that use a 20-year data record of satellite data indicate that tundra is greening in the Arctic, suggesting an increase in photosynthetic activity and net primary production. Modeling studies generally simulate a small net carbon sink for the distribution of Arctic tundra, a result that is within the uncertainty range of field-based estimates of net carbon exchange. Applications of process-based approaches for scenarios of future climate change generally indicate net carbon sequestration in Arctic tundra as enhanced vegetation production exceeds simulated increases in decomposition. However, methane emissions are likely to increase dramatically, in response to rising soil temperatures, over the next century. Key uncertainties in the response of Arctic ecosystems to climate change include uncertainties in future fire regimes and uncertainties relating to changes in the soil environment. These include the response of soil decomposition and respiration to warming and deepening of the soil active layer, uncertainties in precipitation and potential soil drying, and distribution of wetlands. While there are numerous uncertainties in the projections of process-based models, they generally indicate that Arctic tundra will be a small sink for carbon over the next century and that methane emissions will increase considerably, which implies that exchange of greenhouse gases between the atmosphere and Arctic tundra ecosystems is likely to contribute to climate warming.     

PM2.5: global progress in controlling the motor vehicle contribution

It is well established that ambient particles in the size range of 2.5 microns or less case a wide variety of adverse health effects. According to a recent study from the World Health Organization, in 2010 these effects resulted in approximately 3.2million premature deaths with vehicles being one of the significant contributors. Diesel vehicle particulate emissions which are virtually all smaller than 2.5 microns raise additional special concerns due to their carcinogenicity and high ratio of black carbon （BC） to organic carbon; black carbon has recently been found to be the second most important contributor to climate change after carbon dioxide. Other pollutants emitted by diesels and other vehicles such as the oxides of nitrogen and volatile organic compounds also contribute to ambient particulate matter smaller than 2.5 microns in size （PM2.5） after undergoing secondary transformations in the atrno- sphere. Technologies have dramatically reduce vehicle been developed that can emissions when clean, low sulfur fuels are available and these technologies are being phased in throughout the industrialized world resulting in a global decrease in particulate matter （PM） and BC emissions from vehicles. However the vehicle population is growing rapidly in the developing world, leading to increases in emissions in many countries. Unless these rapidly industrializing countries move to state of the art vehicles and clean fuels, global PM, BC and NOx emissions from road vehicles will start to turn up over the next 10 to 15 years.     

Recycling greenhouse gas fossil fuel emissions into low radiocarbon food products to reduce human genetic damage

Radiocarbon from nuclear fallout is a known health risk. However, corresponding risks from natural background radiocarbon incorporated directly into human genetic material have not been fully appreciated. Here we show that the average person will experience between 3.4 × 10¹⁰ and 3.4 × 10¹¹ lifetime chromosomal damage events from natural background radiocarbon incorporated into DNA and histones, potentially leading to cancer, birth defects, or accelerated aging. This human genetic damage can be significantly reduced using low radiocarbon foods produced by growing plants in CO₂ recycled from ordinary industrial greenhouse gas fossil fuel emissions, providing additional incentive for the carbon sequestration.     

First in vitro use of the phenylphosphate carboxylase enzyme in supercritical CO2 for the selective carboxylation of phenol to 4-hydroxybenzoic acid

A new biotechnological synthetic approach to 4-hydroxybenzoic acid is reported. Thauera aromatica cells produce the phenylphosphate carboxylase enzyme that selectively carboxylates phenylphosphate in the para position, without any formation of the ortho isomer. Here we show that the enzyme also works in supercritical carbon dioxide, opening a new technological solution to the recovery of the products that is a key problem when aqueous media are used. The enzyme shows an activity comparable with that shown under CO₂ pressure in aqueous media and does not require the presence of NaHCO₃.     

High diurnal variation in dissolved inorganic C, δ13C values and surface efflux of CO2 in a seasonal tropical floodplain

Diurnal variations in aquatic systems may be a major factor influencing carbon cycling. However, few studies have examined diurnal variation on floodplains and wetlands, especially in the tropics. Stable isotope analysis of dissolved inorganic carbon (δ¹³C_DIC) provides insight into the driving factors behind diurnal physio-chemical variability, but to date, the manual collection of large sample numbers at high temporal frequency has been prohibitive. Here, we report one of the first, high-resolution isotopic studies of δ¹³C_DIC on a tropical floodplain using acidification-interface cavity ring-down spectrometry. Water samples were analysed for δ¹³C_DIC and other water quality parameters at 15-min intervals for 24 h. Our results show significant diurnal variation in both DIC concentration and δ¹³C_DIC. Maximum DIC concentration, recorded overnight, was approximately 100 % greater than during the day. Maximum DIC concentration coincided with minimum δ¹³C_DIC as a result of shifting autotrophic/heterotrophic balance. Changes were significant over small time scales and showed CO₂ gas evasion estimates could vary by as much as 50 % based on measurements taken less than 5 h apart. These data show that to accurately evaluate the role of tropical floodplains in global carbon dynamics, a comprehensive understanding of diurnal variation will be essential.     

Photosynthesis and carbon storage between tides in a brown alga, Fucus vesiculosus

Intertidal macroalgae may spend a significant part of their lives in air. During photosynthesis in air, they encounter much lower concentrations of inorganic carbon than in seawater. Because they accumulate inorganic carbon from seawater, we investigated whether they similarly accumulate it from air. We measured photosynthesis in the intertidal species Fucus vesiculosus L. during 1990 and 1991 with a gas-phase O₂ electrode or CO₂-exchange apparatus in air and with a liquid-phase O₂ electrode in seawater. Maximum rates were rapid and similar in air and seawater regardless of the method. Tissue from seawater could carry on photosynthesis in CO₂-free air, indicating that carbon was stored in the tissue. After 2 h, this store was depleted and photosynthesis ceased. Supplying CO₂ in air replenished the store. Under identical conditions, terrestrial C₃ and C₄ species showed no evidence of this store, but a CAM (crassulacean acid metabolism) species did. However, in contrast to the CAM behavior, F. vesiculosus did not store CO₂ significantly in the dark. We found a small acid-releasable pool of carbon in the tissue that disappeared as photosynthesis depleted the carbon store. However, the pool was too small to account for the total carbon stored. While CO₂ was being acquired or released from the store in the light, photosynthesis was not inhibited by 21% O₂. These results indicate that there are two parallel paths for the supply of CO₂ to photosynthesis. The first depends on inorganic carbon in seawater or in air and supports rapid photosynthesis. The second involves CO₂ slowly released from an organic intermediate. The release protects CO₂ fixation from the inhibitory effects of 21% O₂. Photosynthesis in F. vesiculosus thus appears to be C₃-like in its rapid fixation of CO₂ from a small inorganic pool into phosphoglycerate. However, it is C₄-like in its pre-fixation of carbon in an organic pool in the light, and is CAM-like in its ability to slowly use this pool as a sole source of CO₂. The organic pool may serve to protect photosynthetic CO₂ fixation against the inhibitory effects of O₂ in air and in the boundary layer in seawater. Received: 6 March 1998 / Accepted: 16 October 1998     

大气CO2升高对土壤碳循环影响的研究进展

土壤有机碳是陆地碳库的重要组成部分,其积累和分解的变化直接影响全球的碳平衡。据估计,全球土壤（表层1m）有机碳积累总量相当于大气中碳总量的2～3倍。土壤是温室气体的源或汇,土壤碳库的变化将影响大气C02的浓度,因此,土壤碳库对人类活动的响应也是全球碳循环和全球变化研究的热点。在全球变化的大背景下,大气CO2升高导致植被生态系统碳平衡的改变进而对土壤碳循环产生影响。总结了陆地生态系统碳循环对大气C02浓度升高响应的主要生物学机制及过程,简述了大气C02浓度升高对影响土壤碳输入和输出的各因素的研究进展,并指出未来研究的主要方向。在大气C02浓度升高条件下,陆地生态系统碳循环的变化主要反映在以下几个方面：1）不同类型植物群落的净初级生产力（NPP）显著增加,但湿地植物的净初级生产力也有可能降低;2）光合产物向根系分配的数量增加,地上／地下生物量降低,根系形态发生变化,根系周转速率和根系分泌等过程的碳流量提高;3）植物含氮量降低,C／N提高,次生代谢产物增加,微生物生长受到抑制,植物残体分解速率降低;4）土壤呼吸速率显著增加,提高幅度受植物类型与土壤状况的影响;5）进入土壤的植物残体及分泌物的数量和性质影响土壤酶的活性,脱氢酶和转化酶活性增加,酚氧化酶和纤维素酶受植物类型与环境条件的影响;6）土壤中真菌的数量的增加幅度要高于细菌;7）CH4释放量增加,在植物的生长期表现更为明显。由于陆地生态系统碳循环的复杂性,研究结果仍有很大的不确定性。大气C02浓度升高与全球变化的其它表现间的交互作用将是今后研究的重点,同时由于土壤碳循环是一个由微生物介导的生物地球化学循环过程,因此,加强陆地生态系统碳循环的微生物机制研究也将为全面理解碳循环的过程提供更加准确的研究理论基础。     

基于斑马鱼毒理基因组学的化学品测试技术研究进展

大量缺乏毒性信息的化学品最终进入环境水体,对人类及生态生物产生潜在的危害与风险。提高化学品生物毒性测试与评估技术的通量和效率,是实现毒害化学物质环境与生态健康风险防控的关键。作为一种可以实现高通量测试的脊椎动物模型,斑马鱼胚胎测试在化学品的毒性评估中应用广泛。随着组学技术的发展,毒理基因组学可有效提取毒害化学品致毒过程中干扰生物学通路的信息。这些机制信息可用于对单物质或复合污染物生物毒性的筛选和预测。本文综述了不同斑马鱼胚胎测试技术在化学品毒性筛选评估管理与水环境复合污染毒性监测中的发展和应用,详细介绍了一种新型斑马鱼胚胎简化转录组学技术的方法流程和优势,并探讨了综合斑马鱼胚胎毒性测试、行为分析和组学等不同测试技术在化学品毒性测试、环境监测与评价中的应用前景。     

Carbon nanotubes and Cu–Zn nanoparticles synthesis using hyperaccumulator plants

This article reports a novel way to synthesize carbon nanotubes and Cu/ZnO nanoparticles using metal hyperaccumulator plants. Metal hyperaccumulator plants are traditionally used for phytoremediation to clean soil polluted by toxic metals. However, the transfer of toxic metals in plant shoots and leaves is an environmental issue because animals and other living organisms feeding on plants will transfer the metals to the ecosystem. Therefore, we suggest that hyperaccumulator plants could be used to synthesize nanoparticles. Here, Brassica juncea L., a Cu-hyperaccumulator plant, was collected around a copper mine and used as a raw chemical to produce carbon nanotubes and Cu/ZnO nanoparticles. The chlorophyll in shoots of B. juncea plants was ethanol extracted to yield chlorophyllin. Cu and Zn were extracted by HNO₃ to form Cu/Zn(NO₃)₂. The chlorophyllin reacted with Cu/Zn(NO₃)₂ to form Cu/Zn chlorophyllin. Cu/ZnO nanoparticles were synthesized by direct precipitation of Cu/Zn chlorophyllin with NaOH and ethanol. The vascular bundles in B. juncea plants, which have been purified and carbonized by HNO₃, were rapidly heated to about 400°C and then they were cooled to room temperature to obtain carbon nanotubes. Results indicate that the outer diameter of carbon nanotubes was around 80 nm. Cu/ZnO nanoparticles have a Cu_0.05Zn_0.95O composition, and had a diameter of about 97 nm. Our study not only inspires the search for a new strategy on the synthesis of nanostructure from renewable natural products, but also breaks through the traditional and limited ideas about the reuse of metals by hyperaccumulator plants.     

Climate change and forests of the future: managing in the face of uncertainty.

We offer a conceptual framework for managing forested ecosystems under an assumption that future environments will be different from present but that we cannot be certain about the specifics of change. We encourage flexible approaches that promote reversible and incremental steps, and that favor ongoing learning and capacity to modify direction as situations change. We suggest that no single solution fits all future challenges, especially in the context of changing climates, and that the best strategy is to mix different approaches for different situations. Resources managers will be challenged to integrate adaptation strategies (actions that help ecosystems accommodate changes adaptively) and mitigation strategies (actions that enable ecosystems to reduce anthropogenic influences on global climate) into overall plans. Adaptive strategies include resistance options (forestall impacts and protect highly valued resources), resilience options (improve the capacity of ecosystems to return to desired conditions after disturbance), and response options (facilitate transition of ecosystems from current to new conditions). Mitigation strategies include options to sequester carbon and reduce overall greenhouse gas emissions. Priority-setting approaches (e.g., triage), appropriate for rapidly changing conditions and for situations where needs are greater than available capacity to respond, will become increasingly important in the future.     

Efficient adsorption of carbon dioxide and methane on activated carbon prepared from glycerol with potassium acetate

In the context of global warming and the energy crisis, emissions to the atmosphere of greenhouse gases such as carbon dioxide (CO₂) and methane (CH₄) should be reduced, and biomethane from landfill biogas should be recycled. For this, there is a need for affordable technologies to capture carbon dioxide, such as adsorption of biogas on activated carbon produced from industrial wastes. Here we converted glycerol, a largely available by-product from biodiesel production, into activated carbon with the first use of potassium acetate as an activating agent. We studied adsorption of CO₂ and CH₄ on activated carbon. The results show that activated carbon adsorb CO₂ up to 20% activated carbon weight at 250 kPa, and 9% at atmospheric pressure. This is explained by high specific surface areas up to 1115 m²g⁻¹. Moreover, selectivity values up to 10.6 are observed for the separation of CO₂/CH₄. We also found that the equivalent CO₂ emissions from activated carbon synthesis are easily neutralized by their use, even in a small biogas production unit.

     

Recent advances in the photocatalytic reduction of carbon dioxide

Fossil fuels are currently the major energy source and are rapidly consumed to supply the increasing energy demands of mankind. CO₂, a product of fossil fuel combustion, leads to climate change and will have a serious impact on our environment. There is an increasing need to mitigate CO₂ emissions using carbon–neutral energy sources. Therefore, research activities are devoted to CO₂ capture, storage and utilization. For instance, photocatalytic reduction of CO₂ into hydrocarbon fuels is a promising avenue to recycle carbon dioxide. Here we review the present status of the emission and utilization of CO₂. Then we review the photocatalytic conversion of CO₂ by TiO₂, modified TiO₂ and non-titanium metal oxides. Finally, the challenges and prospects for further development of CO₂ photocatalytic reduction are presented.     

Interactive effects of pH,temperature and light during ammonia toxicity events in Elodea canadensis

Increased nutrient loading threatens many freshwater ecosystems. Elevated temperatures may increase the sensitivity to eutrophication in these ecosystems. Higher concentrations of possibly toxic reduced nitrogen (NH _x ) in the water layer may be expected as production and anaerobic breakdown rates will increase. Apart from temperature, NH _x and its effect on aquatic macrophytes will also depend on pH and light. We examined the interactive effects of NH _x , temperature, pH and light on Elodea canadensis in a full factorial laboratory experiment. Results demonstrate that high NH _x and high temperature together with low pH and low light causes the strongest toxic effects regarding relative growth rate and leaf tissue mortality. The adverse effects of high temperature and low light are most likely caused by increased metabolic activity and reduced photosynthesis, respectively. Severe toxicity at low pH compared to high pH can be ascribed to the ability of E. canadensis to induce a specialised bicarbonate-concentrating pathway at high pH, resulting in much higher carbon availability, needed for detoxification of NH _x . We conclude that NH _x toxicity will become more pronounced under higher temperatures, but that effects on aquatic macrophytes will strongly depend on pH of the water layer and specific metabolic adaptations of different species.     

Estimating marine biogeochemical rates of the carbonate pH system—A Kalman filter tested

Oxygen (O₂), nitrate (NO₃), dissolved inorganic carbon (DIC) or pCO₂, and pH or total alkalinity (TA), are useful indices of marine chemical, physical and biological processes operating on varying time-scales. Although these properties are increasingly being monitored at high frequency, they have not been extensively used for studying ecosystem dynamics. We test whether we can estimate time-evolving biogeochemical rates (e.g. primary production, respiration, calcification and carbonate dissolution, and nitrification) from synthetic high frequency time-series of O₂, NO₃, DIC, pCO₂, TA or pH. More specifically, a Kalman filter has been implemented in a very simplified biogeochemical model describing the dynamics of O₂, NO₃, DIC and TA and linking the concentration data to biogeochemical fluxes. Different sets of concentration data are assimilated and biogeochemical rates are estimated. The frequency of assimilation required to get acceptable results is investigated and is compared with the frequency of sampling in the field or in controlled experimental settings.Smoothing of the data to remove data noise before assimilation improves the estimation of the biogeochemical rates. The best estimated rates are obtained when assimilating O₂, NO₃ and TA although the assimilation of DIC instead of TA also gives satisfactory results. In case pH or pCO₂ is assimilated rather than DIC or TA, the linearization of the (now nonlinear) observation equation introduces perturbations and the Kalman filter behaves suboptimal. We conclude that, given the resolution of data required, the tool has potential to estimate biogeochemical rates of the carbonate system under controlled settings.