The contemporary copper cycle of Asia

A regional stock and flow model for an industrial metal was developed based on the substance-flow framework. Using this model, the contemporary copper cycle of the Asian region was constructed by aggregating country-level production and import and export data for different stages of the copper cycle. The reliability and availability of data were assessed both qualitatively and quantitatively. Asia as a region is a net importer of copper. There is a significant build-up of copper in use at a rate of nearly 3TgCu/year. The per capita generation of copper waste (0.4kgCu/(capita-year)) and the rate of secondary recovery of copper are low compared with Europe and North America. Japan's rates of use, waste generation, and recycling of copper are all much larger than the continental average. A tremendous potential exists in the region to utilize the copper content of the in-use reservoir, and subsequently to enhance copper recycling rates in the future. A set of metrics for the copper cycle is suggested in order to address sustainability issues related to resource policy and the environmental management of copper.     

Occurrence, distribution, and ecological risk assessment of DDTs and heavy metals in surface sediments from Lake Awassa—Ethiopian Rift Valley Lake

Dichlorodiphenyltrichloroethanes (DDTs) and heavy metals are ubiquitous contaminants with high bioaccumulation and persistence in the environment, which can have adverse effects on humans and animals. Although applications of DDTs have been banned in many countries, developing countries like Ethiopia are still using these for agricultural and medicinal purposes. In addition, heavy metals are naturally present in the aquatic environment and distributed globally. In this study, the occurrence, distribution, and ecological risk of DDTs and heavy metals in surface sediments from one of the Ethiopian rift valley lakes were studied. Twenty-five surface sediment samples from Lake Awassa, Ethiopia were collected and analyzed for DDTs and heavy metals. Results showed that concentrations of total DDTs ranged from 3.64 to 40.2 ng/g dry weight. High levels of DDTs were observed in the vicinity of inflow river side and coastal areas with agricultural activities. The heavy metals content were followed the order Zn?>?Ni?>?Pb?>?Cu?>?Cr?>?Co?>?As?>?Cd?>?Hg. Correlation analysis and principal components analysis demonstrated that heavy metals were originated from both natural and anthropogenic inputs. The levels of DDE and DDD in surface sediments exceeded the sediment quality guideline values, indicating that adverse effects may occur to the lake. A method based on toxic-response factor for heavy metals revealed that the calculated potential ecological risk indices showed low ecological risk for the water body.     

Spider orientation and hub position in orb webs

Orb-web building spiders (Araneae: Araneoidea, Uloboridae) can be considered as territorial central place foragers. In territorial central place foragers, the optimal foraging arena is circular, with the forager sitting in its centre. In orb webs, the spider’s orientation (head up or head down) whilst waiting for prey on the hub of its web and the downwards–upwards asymmetry of its running speeds are the probable causes for the observed deviation of the hub from the web’s centre. Here, we present an analytical model and a more refined simulation model to analyse the relationships amongst the spider’s running speeds, its orientation whilst waiting for prey and the vertical asymmetry of orb webs. The results of our models suggest that (a) waiting for prey head down is generally favourable because it allows the spider to reach the prey in its web on average quicker than spiders waiting head up, (b) the downwards–upwards running speed asymmetry, together with the head-down orientation of most spiders, are likely causes for the observed vertical asymmetry of orb webs, (c) waiting head up can be advantageous for spiders whose downwards–upwards running speed asymmetry is small and who experience high prey tumbling rates and (d) spiders waiting head up should place their hub lower than similar spiders waiting head down.     

Effects of using arsenic–iron sludge wastes in brick making

The arsenic–iron sludge generated in most of the treatment systems around the world is discharged into the nearest watercourse, which leads to accumulative rise of arsenic and iron concentrations in water. In this study, attempts were made to use the arsenic–iron sludge in making bricks and to analyze the corresponding effects on brick properties. The water treatment plant sludge is extremely close to brick clay in chemical composition. So, the sludge could be a potential substitute for brick clay. This study involved the addition of sludge with ratios 3%, 6%, 9% and 12% of the total weight of sludge–clay mixture. The physical and chemical properties of the produced bricks were then determined and evaluated and compared to control brick made entirely from clay. Results of different tests indicated that the sludge proportion and firing temperature were the two key factors in determining the quality of bricks. The compressive strength of 3%, 6%, 9% and 12% sludge containing brick samples were found to be 14.1 MPa, 15.1 MPa, 9.4 MPa and 7.1 MPa, respectively. These results indicate that the compressive strength of prepared bricks initially increased and then decreased with the increase of sludge proportion. Leaching characteristics of burnt bricks were determined with the variation of pH at a constant temperature. The optimum amount of sludge that could be mixed with clay to produce good bonding of clay–sludge bricks was found to be 6% (safely maximum) by weight.     

Effect of losing on male fights of broad-horned flour beetle, Gnatocerus cornutus

Experience-dependent tactics of males trying to gain access to females were examined in the beetle Gnatocerus cornutus, which engages in male–male fighting for mates. In male fights, subsequent behavior is modified by winning and losing experiences. Males, therefore, may choose between several behavioral tactics to obtain a mate, based on his previous fighting experience. In G. cornutus, we examined for how long aggressive behaviors were modified by experiences of winning or losing, i.e., the duration of the prior experience effect. Losing decreased a male's frequency of fighting for 4 days, and few defeated males fought any male regardless of the opponent's size. By the fifth day, this effect disappeared. No modulation of male behavior due to winning was observed. Furthermore, the experience of losing not only decreased a male's aggressiveness but also switched the male behavior from fighting to dispersal from the fight site to another site. In future, it is necessary to clarify why the optimal term of the losing experience is 4 days in this beetle.     

Pre-copulatory sexual selection in the cigarette beetle Lasioderma serricorne

Traditional concepts of sexual selection and sexual conflict make different predictions about the costs and benefits to females of exposure to males with higher mating success. The traditional concepts of sexual selection assume that females benefit from their mate choices, whereas sexual conflict assumes that the females suffer greater costs by mating with males who have greater mating success and thus reduce their fitness. In order to understand how mate choice evolves, it is necessary to estimate the overall effect of mate choice on female fitness. However, relatively few studies have conducted that investigation. In this study, we investigated the direct and indirect effects of mating with attractive males on the fitness of females in the cigarette beetle Lasioderma serricorne. Mating with attractive males increased the number of female offspring but did not affect female longevity. Additionally, we found evidence that attractive males sire highly attractive sons. Thus, mating with an attractive male provides direct and indirect benefits but no fitness cost to female L. serricorne.     

Pore structure and adsorption properties of carbonized material prepared from waste paper

We have already reported the adsorptivity and pore structure of activated carbon made from waste newspaper in order to use the waste paper for purposes other than paper-making stock. However, manufacturing the activated carbon may not necessarily be an advantageous method based on environmental concerns and the effective use of the resource because the reaction during the activating process is endothermic and the amount of carbon consumed is significant. Here, we examine the pore structure and adsorption properties of waste newspaper used as an adsorbent in the form of a carbonized material. Waste newspaper was carbonized for 2 h in the temperature range 400°–1000°C. The specific surface area of the carbonized material obtained, 418 m²/g, was highest for the sample carbonized at 800°C, which was equal to or greater than that of commercially available charcoal. Moreover, the iodine adsorption number of 581 mg/g was the highest and the rate of adsorption was the fastest for the sample carbonized at 800°C. However, the humidity control capability was highest for the material carbonized at 600°–700°C. It has been determined that it is advantageous to carbonize waste paper at 800°C in order to use the carbonized material as an adsorbent, while carbonization at 600°–700°C is more advantageous for use as a humidity control material. Received: June 23, 2000 / Accepted: January 17, 2001     

Porous structure of activated carbon prepared from waste newspaper

In an earlier report, we presented a method for preparing activated carbon from waste newspaper as a way to recycle used paper for a purpose other than producing raw material for paper-making. In this article, we consider the porous structure of the activated carbon that affects its adsorption properties for various substances. The specific surface area of activated carbon prepared from waste newspaper was 838 m²/g, the micropore volume was 0.368 ml/g, and the mesopore volume was 0.138 ml/g, which is about the same as commercially available activated carbon. The activated carbon prepared from waste newspaper usually has a high content of ash, which makes little contribution to the adsorption properties. In particular, as compared with reagent-activated carbon, the quantities of mesopores with a pore radius of 3–25 nm and macropores with a pore radius of 25–250 nm were 8 and 14 times larger, respectively. Activated carbon prepared from waste newspaper has a well-developed porous structure, particularly in the mesopore and macropore ranges. Received: July 12, 1999 / Accepted: March 8, 2000