Eco-efficiency indicator framework implemented in the metallurgical industry: part 2—a case study from the copper industry

Purpose

Sustainability differentiation has become an important issue for companies throughout the value chain. There is thus a need for detailed and credible analyses, which show the current status and point out where improvements can be done and how. The study describes how a comprehensive product-centric eco-efficiency indicator framework can be used to evaluate, benchmark, and communicate the sustainability of a copper production value chain. The indicator framework, together with the suggested data collection and simulation methods, aims at evaluating the whole system, while still enabling a focus on scopes of different width. The status of the environment, current production technologies, location-specific and process-specific issues all play a role in achieving sustainable development.

Methods

Copper cathode production from copper ore was chosen to exemplify the developed framework. Data sets from a simulation tool were used when available and LCI databases and LCA software were utilized for the remaining steps. The value chain is analyzed and the benchmark for each indicator built according to the new Gaia Refiner indicator framework. This method enables analysis of specific production steps with a higher degree of accuracy.

Results and discussion

The case study shows how some important environmental sustainability issues in copper production can be analyzed and benchmarked within a product group. Benchmark data is collected and used in the analysis for the selected system scope. Data availability is still an issue and the example shows which areas require more information in this context so that products and value chains can be benchmarked in the future on a more consistent basis. The energy mix, chemical use, and land use contribute to potential environmental sustainability risks within the product benchmarking group, while emissions control shows competitive environmental sustainability advantages for the case study.

Conclusions

The methodology is shown to work well in highlighting the sustainability advantages and risks of value chains in copper production with the selected system scope in a visual manner through the Sustainability Indicator “Flower.” The importance of a baseline is clear. The effect of the metal ore grade on the results shows that the scalability of the analysis system is very important. Scaling the system scope up will show the differences in varying value chains and scaling the system scope down will show efficiency differences between more similar value chains, thus visualizing where innovation has the biggest impact.

     

Expression of Human Glucose Transporter Type 1 and Rat Hexokinase Type II Complementary DNAs in Rainbow Trout Embryos: Effects on Glucose Metabolism

Sugars are utilized poorly in fish mainly because of low rates of transport across plasma membrane and phosphorylation. To evaluate whether it is possible to augment carbohydrate metabolism in fish using heterologous genes, expression of human glucose transporter type 1 (hGLUT1) and rat hexokinase type II (rHKII) complementary DNAs cloned with cytomegalovirus promoter was followed in rainbow trout embryos. Both genes were transcribed. Hexokinase activity, undetectable in control, was found in transformed blastulas. Increased rates of ¹⁴C-methylglucose uptake and sensitivity to cytochalasin B indicated the presence of facilitative hexose transport due to hGLUT1 expression. Effect of hGLUT1 on production of ¹⁴CO₂ from glucose was greater than that of rHKII. Coexpression of the genes did not increase the rate of glucose oxidation compared with expression of hGLUT1 alone. Received; accepted June 30, 1998.     

Glucose transport in a methylotrophic yeast Hansenula polymorpha

Glucose transport was studied in a methylotrophic yeast Hansenula polymorpha . Two kinetically different glucose transport systems were revealed in cells grown under different growth conditions. Glucose-repressed cells exhibited a low-affinity transport system ( K _m for glucose 1.75 mM) while glucose-derepressed and ethanol-grown cells had a high-affinity transport system ( K _m for glucose 0.05–0.06 mM). The high- and low-affinity transport systems differed in substrate specificity, sensitivity to pH, dinitrophenol and protonophore carbonyl cyanide- m -chlorophenyl-hydrazone. The kinetic rearrangement of the glucose transport system in response to altered growth conditions was dependent on de novo protein synthesis.     

Molecular characterization and homology modeling of spermidine synthase from <Emphasis Type="Italic">Synechococcus</Emphasis> sp. PCC 7942

Spermidine synthase (Spds) catalyzes the formation of spermidine by transferring the aminopropyl group from decarboxylated S-adenosylmethionine (dcSAM) to putrescine. The Synechococcus spds gene encoding Spds was expressed in Escherichia coli. The purified recombinant enzyme had a molecular mass of 33 kDa and showed optimal activity at pH 7.5, 37?°C. The enzyme had higher affinity for dcSAM (K _m, 20 µM) than for putrescine (K _m, 111 µM) and was highly specific towards the diamine putrescine with no activity observed towards longer chain diamines. The three-dimensional structural model for Synechococcus Spds revealed that most of the ligand binding residues in Spds from Synechococcus sp. PCC 7942 are identical to those of human and parasite Spds. Based on the model, the highly conserved acidic residues, Asp89, Asp159 and Asp162, are involved in the binding of substrates putrescine and dcSAM and Pro166 seems to confer substrate specificity towards putrescine.     

Maternal effects in vulnerability to eye‐parasites and correlations between behavior and parasitism in juvenile Arctic charr

Hatchery‐reared fish show high mortalities after release to the wild environment. Explanations for this include potentially predetermined genetics, behavioral, and physiological acclimation to fish farm environments, and increased vulnerability to predation and parasitism in the wild. We studied vulnerability to Diplostomum spp. parasites (load of eye flukes in the lenses), immune defense (relative spleen size) and antipredator behaviors (approaches toward predator odor, freezing, and swimming activity) in hatchery‐reared juvenile Arctic charr (Salvelinus alpinus) using a nested mating design. Fish were exposed to eye‐fluke larvae via the incoming water at the hatchery. Fish size was positively associated with parasite load, but we did not find any relationship between relative spleen size and parasitism. The offspring of different females showed significant variation in their parasite load within sires, implying a dam effect in the vulnerability to parasites. However, the family background did not have any effect on spleen size. In the mean sire level over dams, the fish from the bolder (actively swimming) families in the predator trials suffered higher loads of eye flukes than those from more cautiously behaving families. Thus, the results indicate potentially maternally inherited differences in vulnerability to eye‐fluke parasites, and that the vulnerability to parasites and behavioral activity are positively associated with each other at the sire level. This could lead to artificial and unintentional selection for increased vulnerability to both parasitism and predation if these traits are favored in fish farm environments.     

Silicon load and the development of diatoms in three river-lake systems in countries surrounding the Baltic Sea

We studied the formation of dissolved silicon loads from rivers to lakes, the development of diatoms in lakes and the role of climatic forcing on the silicon cycle in three river-lake systems in Sweden, Estonia and Northern Germany. We found coherent seasonality in the silicon loads of the two northern rivers, which was probably caused by the common snow-type hydrology of the catchments as distinct from the rain-type hydrology of the catchment, further south. The similarity among lakes in the dynamics of the Si-related variables studied resulted from similarities in mean lake depth and mixing type rather than the climatic regime. Among the variables measured at the three sites, river water discharge responded most coherently to climatic forcing as synchronized by the North Atlantic Oscillation winter index (NAOw). Water discharge and Si load were strongly linked variables and showed coherent patterns among the river systems. We found significant season-specific correlations of the NAOw with either the biomass or the share of diatoms in each lake, but no coherent pattern among the lakes. Our results indicate that processes driven by water discharge are more coherent across regions than in-lake processes.     

Relationships between morphometry,geographic location and water quality parameters of European lakes

I addressed the question how lake and catchment morphometry influences water chemistry and water quality over a large scale of European lakes, and developed the regression equations between most closely related morphometric and water quality indices. I analysed the data of 1,337 lakes included in the European Environment Agency (EEA) database, carrying out separate analyses for three basic lake types: large lakes (area ≥100 km², 138 lakes), shallow lakes (mean depth ≤3 m, 153 lakes) and large and shallow lakes (area ≥100 km² and mean depth ≤8 m, 35 lakes). The study revealed that in Europe, the lakes towards North are larger but shallower and have smaller catchment areas than the southern lakes; lakes at higher altitudes are deeper and smaller and have smaller catchment areas than the lowland lakes. Larger lakes have generally larger catchment areas and bigger volumes, and they are deeper than smaller lakes, but the relative depth decreases with increasing surface area. The lakes at higher latitudes have lower alkalinity, pH and conductivity, and also lower concentrations of nitrogen and phosphorus while the concentration of organic matter is higher. In the lakes at higher altitudes, the concentration of organic matter and nutrient contents are lower and water is more transparent than in lowland lakes. In larger lakes with larger catchment area, the alkalinity, pH, conductivity and the concentrations of nutrients and organic matter are generally higher than in smaller lakes with smaller catchments. If the lake is deep and/or its residence time is long, the water is more transparent and the concentrations of chlorophyll a, organic matter and nutrients are lower than in shallower lakes with shorter residence times. The larger the catchment area is with respect to lake depth, area and volume, the lower is the water transparency and the higher are the concentrations of the nutrients, organic matter and chlorophyll as well as pH, alkalinity and conductivity. The links between lake water quality and morphometry become stronger towards large and shallow lakes. Along the decreasing gradients of latitude, altitude and relative depth, the present phosphorus concentration and its deviation from the reference concentration increases.     

Protein-mediated Selective Enclosure of Early Replicators Inside of Membranous Vesicles: First Step Towards Cell Membranes

Containment in cell membranes is essential for all contemporary life, and apparently even the earliest life forms had to be somehow contained. It has been postulated that random enclosure of replicating molecules inside of spontaneously assembled vesicles would have formed the initial cellular ancestors. However, completely random re-formation or division of such primitive vesicles would have abolished the heritability of their contents, nullifying any selective advantage to them. We propose that the containment of the early replicators in membranous vesicles was adopted only after the invention of genetically encoded proteins, and that selective enclosure of target molecules was mediated by specific proteins. A similar containment process is still utilised by various RNA- and retroviruses to isolate their replication complexes from the host’s intracellular environment. Such selective encapsulation would have protected the replicators against competitor and parasitic sequences, and provided a strong positive selection within the replicator communities.