Derivation of correlations to evaluate the impact of retrofitted post-combustion CO2 capture processes on steam power plant performance

When integrating a post-combustion CO₂ capture process and CO₂ compression into a steam power plant, the three interface quantities heat, electricity and cooling duty must be satisfied by the power plant, leading to a loss in net efficiency. The heat duty shows to be the largest contributor to the overall net efficiency penalty of the power plant. Additional energy penalty results from the cooling and electric power duty of the capture and compression units.In this work, the dependency of the energy penalty on the quantity and quality of the heat duty is analyzed and quantified for a state-of-the-art hard coal fired power plant. Furthermore, the energy penalty attributed to the additional cooling and power duty is quantified. As a result correlations are provided which enable to predict the impact of the heat, cooling and electricity duty of post-combustion CO₂ capture processes on the net output of a steam power plant in a holistic approach.     

Rapid assessment of different oxygenic phototrophs and single-cell photosynthesis with multicolour variable chlorophyll fluorescence imaging

We present a new system for microscopic multicolour variable chlorophyll fluorescence imaging of aquatic phototrophs. The system is compact and portable and enables microscopic imaging of photosynthetic performance of individual cells and chloroplasts using different combinations of blue, green, red or white light. Automated sequential exposure of microscopic samples to the three excitation colours enables subsequent deconvolution of the resulting fluorescence signals and colour marking of cells with different photopigmentation, i.e., cyanobacteria, green algae, red algae and diatoms. The photosynthetic activity in complex mixtures of phototrophs and natural samples can thus be assigned to different types of phototrophs, which can be quantified simultaneously. Here, we describe the composition and performance of the new imaging system and present applications with both natural phytoplankton and microalgal culture samples.     

Environmental risk assessment of genetically modified plants - concepts and controversies

Purpose

The purpose of the study is the enhancement of criticality assessments for resources in order to address function specific factors like dissipation, recycling, bio-activity and toxicity. The developed methodology is applied to platinum-containing cytostatic drugs and automotive catalytic converters.

Methods

The study is methodically based on an analysis of resource specific factors like exploration rates, reserves-to-production ratio and regional distribution of exploration areas as well as on the investigation of product/functional depending factors like recycling rates, dissipation rates, bio-diversity and toxicity. Taking into account that economic and ecological risks may occur at any stage of the supply, consumption and dissipation processes, the whole life cycles of the two analyzed products (cytostatic drugs and automotive catalytic converters) are considered. As an approach to reduce potential economic and ecological risks the study is especially focused on recycling strategies.

Background

In order to get a better understanding of platinum as an essential resource for the development of our society the history and the cultural impact of the term "resource" are introduced.

Results & Discussion

The availability of platinum is crucial for several products of our modern society. Areas of application are e.g. jewellery, automotive catalytic converters, investments (coins, bars), computers, mobile devices, fertilizers and cytostatic drugs. Economic risks are caused by limited sources and dynamic demand of new application areas like fuel cells and drugs. Platinum-containing drugs are used for the treatment of several kinds of cancer such as testicular, breast, colon and prostate. Currently the pharmaceutical industry requires 6,9 tons per year (3 percent of the total demand of platinum). Due to the improvement of medical standards and the ageing society, especially in developing countries, the demand of platinum-containing drugs will rise significantly. The dissipation of toxic soluble salts and the lack of advanced waste-water treatment and recycling systems is a problem of the usage of platinum-containing drugs. Compared with cytostatic drugs (14.6 kg/a for Germany) the dissipation of platinum particles of mobile catalytic converters is much higher (5-20 tons/a only in North America, Europe and Japan; 184,2 kg/a in Germany). On the other hand the emission of platinum nano-particles of automotive catalytic converters seems less critical. Furthermore advanced recycling technologies are already available for them.

Conclusions

The evaluation of resources has to consider resource specific and functional depending factors. In order to reduce economic and ecological risks of the dissipation of platinum salts in cytostatic drugs three principle options can be identified: the development of ecologically compatible and cost-effective substitutes, efficient recycling systems and future-oriented sanitary-systems as well as waste-water treatment facilities, which are able to separate platinum salts. Concerning the dissipation of platinum particles of mobile converters relevant research questions are the identification of adequate substitutes as well as the extension of recycling capacities.

Recommendations and perspectives

The study demonstrates a research gap concerning substitutes for automotive catalytic converters as well as for platinum-containing cytostatic drugs. The development and implementation of recycling concepts, technologies and capacities to reuse platinum as a secondary resource is an essential issue. As a consequence the economic and ecological risks can be reduced by increasing the resource efficiency. Special research has to be done concerning the development of future-oriented sanitary-systems and waste-water treatment facilities in order to separate platinum in waste water. Furthermore, if the future demand of new products like fuel cells is considered, a resource conflict concerning the potential functional applications will be evident. In order to address these challenges the criticality assessment has to be enhanced by ethic and social factors.     

A workflow to investigate the impacts of weathered multi-walled carbon nanotubes to the mud snail Lymnaea stagnalis

Environmental Science and Pollution Research - Although the development and application of nanomaterials is a growing industry, little data is available on the ecotoxicological effects on aquatic...     

Handling the phosphorus paradox in agriculture and natural ecosystems: Scarcity,necessity, and burden of P

This special issue of Ambio compiles a series of contributions made at the 8th International Phosphorus Workshop (IPW8), held in September 2016 in Rostock, Germany. The introducing overview article summarizes major published scientific findings in the time period from IPW7 (2015) until recently, including presentations from IPW8. The P issue was subdivided into four themes along the logical sequence of P utilization in production, environmental, and societal systems: (1) Sufficiency and efficiency of P utilization, especially in animal husbandry and crop production; (2) P recycling: technologies and product applications; (3) P fluxes and cycling in the environment; and (4) P governance. The latter two themes had separate sessions for the first time in the International Phosphorus Workshops series; thus, this overview presents a scene-setting rather than an overview of the latest research for these themes. In summary, this paper details new findings in agricultural and environmental P research, which indicate reduced P inputs, improved management options, and provide translations into governance options for a more sustainable P use.     

Mercury levels and trends (1993-2009) in bream (Abramis brama L.) and zebra mussels (Dreissena polymorpha) from German surface waters

Mercury concentrations have been analysed in bream (Abramis brama L.) and zebra mussels (Dreissena polymorpha) collected at 17 freshwater sites in Germany from 1993-2009 and 1994-2009, respectively, within the German Environmental Specimen programme. Mercury concentrations in bream ranged from 21 to 881 ng g⁻¹ wet weight with lowest concentrations found at the reference site Lake Belau and highest in fish from the river Elbe and its tributaries. Statistical analysis revealed site-specific differences and significant decreasing temporal trends in mercury concentrations at most of the sampling sites. The decrease in mercury levels in bream was most pronounced in fish from the river Elbe and its tributary Mulde, while in fish from the river Saale mercury levels increased. Temporal trends seem to level off in recent years. Mercury concentrations in zebra mussels were much lower than those in bream according to their lower trophic position and varied by one order of magnitude from 4.1 to 42 ng g⁻¹ wet weight (33-336 ng g⁻¹ dry weight). For zebra mussels, trend analyses were performed for seven sampling sites at the rivers Saar and Elbe of which three showed significant downward trends. There was a significant correlation of the geometric mean concentrations in bream and zebra mussel over the entire study period at each sampling site (Pearson’s correlation coefficient = 0.892, p = 0.00002). A comparison of the concentrations in bream with the environmental quality standard (EQS) of 20 ng g⁻¹ wet weight set for mercury in biota by the EU showed that not a single result was in compliance with this limit value, not even those from the reference site. Current mercury levels in bream from German rivers exceed the EQS by a factor 4.5-20. Thus, piscivorous top predators are still at risk of secondary poisoning by mercury exposure via the food chain. It was suggested focusing monitoring of mercury in forage fish (trophic level 3 or 4) for compliance checking with the EQS for biota and considering the age dependency of mercury concentrations in fish in the monitoring strategy.     

Partitioning and bioaccumulation of metals from oil sands process affected water in indigenous Parachlorella kessleri

This paper studies the partitioning and bioaccumulation of ten target metals (⁵³Cr, Mn, Co, ⁶⁰Ni, ⁶⁵Cu, ⁶⁶Zn, As, ⁸⁸Sr, ⁹⁵Mo and Ba) from oil sands tailings pond water (TPW) by indigenous Parachlorella kessleri. To determine the role of extracellular and intracellular bioaccumulation in metal removal by P. kessleri, TPW samples taken from two oil sands operators (Syncrude Canada Ltd. and Albian Sands Energy Inc.) were enriched with nutrient supplements.Results indicate that intracellular bioaccumulation played the main role in metal removal from TPW; whereas extracellular bioaccumulation was only observed to some extent for Mn, Co, ⁶⁰Ni, ⁶⁵Cu, ⁸⁸Sr, ⁹⁵Mo and Ba. The FTIR scan and titration of functional groups on the cell surface indicated low metal binding capacity by indigenous P. kessleri. However, it is believed that the dissolved cations and organic ligand content in TPW (such as naphthenic acids) may interfere with metal binding on the cell surface and lower extracellular bioaccumulation. In addition, the total bioaccumulation and bioconcentration factor (BCF) varied during the cultivation period in different growth regimes.     

Volatile nanoparticle formation and growth within a diluting diesel car exhaust

A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric chemistry.