Dynamics of microcystins-LR and -RR in the phytoplanktivorous silver carp in a sub-chronic toxicity experiment

A sub-chronic toxicity experiment was conducted to examine tissue distribution and depuration of two microcystins (microcystin-LR and microcystin -RR) in the phytoplanktivorous filter-feeding silver carp during a course of 80 days. Two large tanks (A, B) were used, and in Tank A, the fish were fed naturally with fresh Microcystis viridis cells (collected from a eutrophic pond) throughout the experiment, while in Tank B, the food of the fish were M. viridis cells for the first 40 days and then changed to artificial carp feed. High Performance Liquid Chromatography (HPLC) was used to measure MC-LR and MC-RR in the M. viridis cells, the seston, and the intestine, blood, liver and muscle tissue of silver carp at an interval of 20 days. MC-RR and MC-LR in the collected Microcystis cells varied between 268-580 and 110-292 microg g(-1) DW, respectively. In Tank A, MC-RR and MC-LR varied between 41.5-99.5 and 6.9-15.8 microg g(-1) DW in the seston, respectively. The maximum MC-RR in the blood, liver and muscle of the fish was 49.7, 17.8 and 1.77 microg g(-1) DW, respectively. No MC-LR was detectable in the muscle and blood samples of the silver carp in spite of the abundant presence of this toxin in the intestines (for the liver, there was only one case when a relatively minor quantity was detected). These findings contrast with previous experimental results on rainbow trout. Perhaps silver carp has a mechanism to degrade MC-LR actively and to inhibit MC-LR transportation across the intestines. The depuration of MC-RR concentrations occurred slowly than uptakes in blood, liver and muscle, and the depuration rate was in the order of blood>liver>muscle. The grazing ability of silver carp on toxic cyanobacteria suggests an applicability of using phytoplanktivorous fish to counteract cyanotoxin contamination in eutrophic waters.     

Improvement in the feeding method to an inclined conveyor designed for the recycling of foundry sand

 The goal of the inclined conveyor method for particle shape separation is to process a large amount of feed material for recycling technology. The high feed rate has been achieved because the movement of particles is faster than for other previously introduced equipment. The separation performance of the apparatus was tested with foundry sand. A large amount of sand was treated, and various processing capacities were studied experimentally. The feed method was improved from point to line with wide troughs to process the higher feed rate. We succeeded in attaining a feed rate of 1.49 × 10⁻³ kg/s with a 0.3-m trough. The space filling, which was an important factor in deciding the capacity of the feed rate, was defined. This method is useful for any kind of line-feed method. Received: March 25, 2002 / Accepted: August 5, 2002     

Salivary cortisol and cortisone levels,and breast milk dioxin concentrations in Vietnamese primiparas

There is a great deal of concern regarding the adverse effects of polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) present in Agent Orange and other herbicides on Vietnam's population and ecosystems. The purpose of this study was to determine the effect of dioxin exposure on adrenal steroids in saliva, and dioxin levels in breast milk, of primiparas in an Agent Orange/dioxin hot-spot and a non-exposed area in Vietnam on the basis of epidemiological research. The subjects were 35 lactating women who had recently given birth to their first or second child. A further sub-study involved eight primiparas from each area. All subjects were aged between 20 and 30 years with infants aged between 4 and 16 weeks. The mean concentration of PCDD, PCDF, and PCDD?+?PCDF toxic equivalents (TEQ) in breast milk in the hot-spot area was significantly higher than in the non-exposed area. Cortisol and cortisone levels in the saliva of primiparas in the hot-spot area were also significantly higher than those in the non-exposed area. There was a significant negative correlation between cortisol and the cortisol/cortisone ratio and PCDD?+?PCDF and PCDF TEQ levels in the hot-spot area. Furthermore, the correlation between cortisol and cortisone and the PCDD + PCDF, PCDD, and PCDF TEQ in the combination of hot spot + non-exposed area was significant according to the curve (bell style). Our results suggest that Agent Orange/dioxin exposure still exerts a major influence on the salivary hormones of the Vietnamese population.     

Efficient waste and pollution abatements for regions in Japan

This paper computes efficient industrial waste and air pollutants abatements for 47 regions in Japan for the period 1992–2002. The variable-returns-to-scale (VRS) data envelopment analysis (DEA) with a single output (real GDP) and seven inputs (labor, real public capital stock, real private capital stock, industrial waste, sulfur oxide, nitrogen oxide, and soot and dust) is used to compute target wastes of each region for each year. The efficient abatement ratios of each region in each year are obtained by comparing the actual to the target amount of a pollutant. Our major findings are: (1) Most regions in Japan have significant room to reduce their pollution since there is a wide gap between efficient and inefficient regions; (2) For each air pollutant, approximately 25–33% of Japan's prefectures can reduce their output by more than 50% without harming regional GDP, and approximately one-third of prefectures can reduce industrial waste more than 30%; (3) Hokkaido is the least efficient region for all years studied and for all waste and pollutants, and target abatement ratios there drastically worsened in the last two sample years; (4) Tokyo, Saitama, Yamanashi, Shiga, Nara, and Tottori are efficient with respect to each type of industrial waste and pollution throughout the study period; (5) many regions in the bottom quartile with respect to real per capita income have significant room to reduce their waste and pollution output; and (6) many regions where energy-intensive industries dominate produce excessive amounts of waste and air pollution compared to other regions.