Producing Cu-loaded algae for feeding experiments: effects of copper on Parachlorella kessleri

Microalgae require several essential metals for optimum growth, which at elevated concentrations may interfere with biochemical and physiological processes, one of them being copper (Cu). The aim of this study is to raise Cu-loaded Parachlorella kessleri as feed for mussels. In order to spike the algae with Cu without lowering their nutritional quality, it is important to know the highest Cu-concentration at which the main parameters remain unaffected, especially in respect to proteins and polysaccharides. The dependence of growth rate, biomass, chlorophyll-a and -b, pheophytin-a, protein, and polysaccharide contents on Cu concentrations are determined. The tests show that P. kessleri is largely unchanged in its nutritional value when exposed to Cu at levels of up to 6?µmol?L^?1. Above 10?µmol?L^?1, toxic effects become obvious, with chlorophyll contents and growth rate being the most sensitive indicators.     

Preliminary experiment on fuel consumption and emission reduction in SI engine using blended bioethanol–gasoline and radiator tube-heater

The objective of this research is to investigate the reduction in fuel consumption and emission in spark ignition engine using blended bioethanol-gasoline and novel radiator-tube heater. Different percentages of ethanol – 0, 5, 10, 15, 20, 25 and 30% – are employed. The blended fuel is then pre-heated by sending it into a tube-heater-installed upper tank radiator which has different shape. The results show a significant reduction in fuel consumption and emission in engine. The best economical fuel consumption occurs in the tube-heater with a fin pipe of 10 mm space at 2.153 × 10^?3 cc per cycle or 5.632%. However, the most economical fuel consumption occurs when 25% of bioethanol is added to fuel at 3.175?×?10^?3 per cycle. This decreases fuel consumption by 8.306%. The highest decrease in fuel consumption occurs when fuel blended with 25% of bioethanol and tube-heater of 10 mm 6.236?×?10^?3 cc per cycle or 16.313% is combined. In terms of emission reduction, the tube-heater with a space of 20 mm between fins (Tube 20) using a fuel mixture of 25% ethanol and 75% gasoline produced the lowest CO emissions.     

Effects of copper on lipid peroxidation,glutathione, metallothionein,and antioxidative enzymes in the freshwater mussel Anodonta anatina

Copper is an essential element to all animals. At elevated concentrations, it is toxic and can participate in the formation of reactive oxygen species, leading to cellular damage. In this study, the ecotoxicological relevance of copper was investigated with freshwater mussels, Anodonta anatina. When the mussels were exposed to copper at environmentally realistic concentrations, either via the water (0.3?µmol?L^?1 Cu) or fed with Cu-loaded algae (equivalent to 0.06?µmol?L^?1 Cu), the level of thiobarbituric acid-reactive substances rose and glutathione decreased. This was associated with the induction of metallothionein and, relative to total protein, of glutathione reductase and the antioxidative enzymes superoxide dismutase, catalase, and glutathione peroxidase. But, since the overall protein-synthetic capacity was hampered by the copper insult, the activities of the enzymes relative to tissue weight and copper concentrations were depressed. During depuration, most parameters started to normalize although not returning to control values within 12 days.     

Combined effects of copper and cadmium on Chlorella pyrenoidosa H.Chick: subcellular accumulation,distribution, and growth inhibition

Disposal of waste into aquatic ecosystems may cause microalgae to be exposed to various metals, e.g. copper and cadmium. The effects caused by combinations of metals may be more serious. Evaluations of subcellular fate, bioaccumulation, and biological effects of metals on aquatic organisms are generally derived from experiments with individual metals. The present study aims to evaluate the effects of exposure of Chlorella pyrenoidosa to copper and cadmium in combination on subcellular accumulation, distribution, and growth. The algae were exposed for 72 h to copper at concentrations of 13 – 25 µmol L^?1, cadmium at about 6 µmol L^?1, and combinations thereof. The levels of copper and cadmium in subcellular organelles, heat-denaturated protein, metal-rich granules, and heat-stable protein were determined by atomic absorption spectrometry. Exposure of C. pyrenoidosa to copper and cadmium in combination inhibited growth more strongly than copper and cadmium individually. Highest accumulation was observed in metal-rich granules and heat-stable proteins. Administration of both metals in combination affected their subcellular distribution: copper was mainly distributed into the metal-rich granules (70%–80%) and heat-stable proteins (9%–24%), cadmium in the metal-rich granules (88%–98%).     

Long-term recovery narratives following major disasters in Southeast Asia

Regional Environmental Change - Most studies of major disasters focus on the impacts of the event and the short-term responses. Some evaluate the underlying causes of vulnerability, but few...     

The use of chitosan of shrimp Penaeus sp. as cadmium adsorbent

Cadmium (Cd) is one of the heavy metals which contaminate the environment including water, air, and soil. At low concentrations, Cd produces adverse effects in aquatic organisms. An effort to reduce the level of Cd was conducted by removing the metal with chitosan. The aim of this study was to study the adsorption of Cd by using chitosan isolated from the shrimp Penaeus sp. as a function of stirring duration and chitosan concentration in aqueous solution. In this study, chitin was isolated by using NaOH 3% and HCl 1.25 N, adding NaOH 50% for the transformation of chitin to chitosan. For the adsorption test, chitosan was added to Cd solutions at concentrations of 0.2, 0.4, or 0.6 g per 10 ml Cd(NO₃)², stirring the solution for 5, 10, or 15 min, respectively. The results showed that the yield of isolated chitosan was 56% of crude prawn shell. The optimum concentration of chitosan was 0.6 g/10 ml with a stirring duration 10 min reducing Cd concentration by 91.7%.