Microbial Leaching of Copper from Waste Electronic Scraps

Microbial leaching was used to mobilize copper from two kinds of waste electronic scraps used as raw materials for printed wire boards. Both of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans used to solubilize copper from the samples. The experimental results demonstrated that the percentages of copper basically increased with decrease of sieve fraction of the samples. The green non-conductive coating of the waste electronic scraps was proved to have little effect on the leaching efficiency of both of the pure culture of Acidithiobacillus ferrooxidans and Acidithiobacil thiooxidans or their mixed culture. Acidithiobacillus ferrooxidans has larger solubilizing capability for copper than Acidithiobacillus thiooxidans.

Technical Note: On methodologies for determining the size-normalised weight of planktic foraminifera

The size-normalised weight (SNW) of planktic foraminifera, a measure of test wall thickness and density, is potentially a valuable palaeo-proxy for marine carbon chemistry. As increasing attention is given to developing this proxy it is important that methods are comparable between studies. Here, we compare SNW data generated using two different methods to account for variability in test size, namely (i) the narrow (50 μm range) sieve fraction method and (ii) the individually measured test size method. Using specimens from the 200–250 μm sieve fraction range collected in multinet samples from the North Atlantic, we find that sieving does not constrain size sufficiently well to isolate changes in weight driven by variations in test wall thickness and density from those driven by size. We estimate that the SNW data produced as part of this study are associated with an uncertainty, or error bar, of about ±11%. Errors associated with the narrow sieve fraction method may be reduced by decreasing the size of the sieve window, by using larger tests and by increasing the number tests employed. In situations where numerous large tests are unavailable, however, substantial errors associated with this sieve method remain unavoidable. In such circumstances the individually measured test size method provides a better means for estimating SNW because, as our results show, this method isolates changes in weight driven by variations in test wall thickness and density from those driven by size.

Technical Note: Determining the size-normalised weight of planktic foraminifera

The size-normalised weight (SNW) of planktic foraminifera, a measure of test wall thickness and density, is potentially a valuable palaeo-proxy for marine carbon chemistry. As increasing attention is given to developing this proxy it is important that methods are comparable between studies. Here, we compare SNW data generated using two different methods to account for variability in test size, namely i) the narrow (50 μm range) sieve fraction method and ii) the individually measured test size method. Using specimens from the 200–250 μm sieve fraction range collected in multinet samples from the North Atlantic, we find that sieving does not constrain size sufficiently well to isolate changes in weight driven by variations in test wall thickness and density from those driven by size. We estimate that these SNW data are associated with an uncertainty, or error bar, of about ±11%. Errors associated with the narrow sieve fraction method may be reduced by decreasing the size of the sieve window, by using larger tests and by increasing the number tests employed. In situations where numerous large tests are unavailable, however, substantial errors associated with this sieve method remain unavoidable. In such circumstances the individually measured test size method provides a better means for estimating SNW because, as our results show, this method isolates changes in weight driven by variations in test wall thickness and density from those driven by size.

Laser-diffraction and pipette-method grain sizing of Dutch sediments: correlations for fine fractions of marine, fluvial, and loess samples

To evaluate correlations between silt and clay fractions determined by pipette method and laser diffraction, samples from Dutch fine marine, fluvial, and loess deposits were analysed by both methods. For fluvial deposits, correlations for fractions <2 and >50 μm were excellent (R2 > 0.95), those for 2–4, 4–8, 16–32 and 32–50 μm were satisfactory (R2 = 0.80 – 0.95), while that for the fraction 8–16 μm had an R2 of only 0.68. For marine deposits, correlations for <2 and >50 μm were in the same range, but those of all other fractions except 8–16 μm were lower. In the loess samples, correlations for all but the 8–16 μm fraction were unsatisfactory. Laser diffraction gave 42% of pipette clay in marine samples, and 62% in fluvial and loess samples if regressions are forced through 0. Sand fractions detected by laser diffraction were 107% of the sieve fraction in marine samples, and 99% in the fluvial samples. Correlations for fractions smaller than reference size are generally better than those for individual size fractions. Both the 2 μm and the 50 μm boundary cause problems in the comparison. The first because of platy shape of clay minerals, and the second due to both a change in method in the pipette/sieving procedure, and to non-sphericity of particles. Apparently, correlations for clay- and silt-size fractions obtained by pipette method and laser diffraction will be different for each type of sediment.

Preliminary observations on living <i>Krithe praetexta praetexta</i> (Sars, 1866), <i>Sarsicytheridea bradii</i> (Norman, 1865) and other marine ostracods in aquaria

More than fifty years ago, Elofson (1941) showed that it is fully possible to maintain living cultures of marine ostracods in aquaria. He concentrated particularly on determining the generation length of several species. In this study, we provide some preliminary observations on the mode of life and morphological variations of marine ostracods kept in aquaria. They derive from a water depth of 40m in the Gullmar Fjord (58°17′N and 11°29′E), west coast of Sweden. The dominant species are Krithe praetexta praetexta (Sars, 1866) and Sarsicytheridea bradii (Norman, 1865). Other species housed in the aquaria are: Jonesia acuminata (Norman, 1865), Palmoconcha guttata (Norman, 1865), Palmoconcha laevata (Norman, 1865), Cytheropteron latissimum (Norman, 1865), Pterygocythereis jonesii (Baird, 1850), Acanthocythereis dunelmensis (Norman, 1865), Robertsonites tuberculatus (Sars, 1866), Elofsonella concinna (Jones, 1857) and Argilloecia conoidea (Sars, 1923).MATERIAL AND METHODSThe study was carried out at the Kristineberg Marine Research Station, west coast of Sweden, from July of 1992 to June of 1994. Sediment from a depth of 40 m in the Gullmar Fjord was sieved to remove the macrofauna and frozen, then thawed to constitute a 10–20 mm thick sediment layer in two 501 aquaria. The sediment consisted of 8 % sand (>63 μm), 44 % silt (>3.9 μm) and 49 % clay (<3.9 μm), and with a water content of 71 % ± 5% (σ = 2.4). Ostracods from the ≥250 μm sieve fraction of the dredge sample (from a depth of 40 m) were added to the aquaria. They were kept. . .

Oxidation rate of elemental sulfur particles with a wide range of sizes

An equation is proposed that describes the oxidation rate of elemental sulfur particles with a wide range of sizes, such as would be found in fertilizers. The only information needed is the mean oxidation rate constant over the period of interest and, from a sieve analysis, the proportions of the total mass in each sieve fraction (ratio of upper to lower size < to 2).

Corrigenda - Oxidation rate of elemental sulfur particles with a wide range of sizes

An equation is proposed that describes the oxidation rate of elemental sulfur particles with a wide range of sizes, such as would be found in fertilizers. The only information needed is the mean oxidation rate constant over the period of interest and, from a sieve analysis, the proportions of the total mass in each sieve fraction (ratio of upper to lower size < to 2).