Plasticity in spawning visits of female damselfish, Stegastes nigricans : effect of distance to mates

Both sexes of the damselfish Stegastes nigricans hold individual territories in which they feed on filamentous algae. At dawn, females visit males' territories to spawn, and the males guard the eggs until hatching. We examined how females' spawning behavior varied according to the distances to their mates. Females usually mated with a single male per morning. The distance to the territory of a mate (0.7–12.8 m) did not affect a female's total spawning time per morning, but affected the number of her spawning visits with that male. Females made many repeated spawning visits when spawning with males at short distances, while they spawned the entire clutch in one visit when spawning with males at long distances. This plasticity in female behavior appears to be related to two costs during the spawning visits: (1) intrusions by other fish to feed on algae in the female's territory during her absence, which may cause the female to return repeatedly to her territory for defense, and (2) attacks on the female by other territorial fish, which increased with the distance to their mates' territories. To minimize the sum of both costs, females should change the number of spawning visits depending on the distance to the males' territories. Received: 30 September 1996 / Accepted after revision: 17 March 1997     

The Truth About Science: A middle school curriculum teaching the scientific method and data analysis in an ecology context

The Truth About Science is a 40-lesson middle school curriculum module that teaches the process of scientific research, integrating mathematics and science concepts and skills. The goal of the curriculum is to teach students to think systematically and statistically about science inquiry. Students participate in each step of the scientific inquiry process, from asking testable research questions, designing unbiased experiments, and collecting their own data, to analyzing these data via graphical representations and statistical summaries, and communicating their research results as both poster and oral presentations. While the necessary statistical skills depend on difficult and abstract mathematical concepts, middle school students have been successful in applying them to their own research projects. The curriculum meets local and national standards in science and mathematics education and fills a gap in available educational materials. It has been piloted and revised through multiple iterations and published by the National Science Teachers Association Press. Feedback from teachers and students has been extremely positive.     

Characteristics of electrolysis, ozonation, and their combination process on treatment of municipal wastewater.

The characteristics of municipal wastewater treatment by electrolysis, ozonation, and combination processes of electrolysis and aeration using three gaseous species (nitrogen [N2], oxygen [O2], and ozone [O3]) were discussed in this research using ruthenium oxide (RuO2)-coated titanium anodes and stainless-steel (SUS304) cathodes. Electrolysis and electrolysis with nitrogen aeration were characterized by a rapid decrease in 5-day biochemical oxygen demand (BODs) and total nitrogen and a slow decrease in chemical oxygen demand (COD). In contrast, ozonation, electrolysis with oxygen aeration, and electrolysis with ozone aeration were characterized by transformation of persistent organic matter to biodegradable matter and preservation of total nitrogen. The best energy efficiency in removing BOD5 and total nitrogen was demonstrated by electrolysis, as a result of direct anodic oxidation and indirect oxidation with free chlorine produced from the chloride ion (Cl-) at the anodes. However, electrolysis with ozone aeration was found to be superior to the other processes, in terms of its energy efficiency in removing COD and its ability to remove COD completely, as a result of hydroxyl radical (*OH) production via cathodic reduction of ozone.     

Estrogenic and thyroid hormone activity of a series of hydroxy-polychlorinated biphenyls

A series of novel synthetic monohydroxy polychlorinated biphenyls (OH-PCBs) (5 trichloro-, 5 tetrachloro- and 5 pentachloro-compounds) have been characterized (1H and 13C NMR and high resolution MS) and their estrogenic and thyroid hormone activities assessed using a yeast two-hybrid assay, both with and without possible metabolic activation by rat liver S9 preparation. Moderate estrogenic activity was found for 2,3,4(')-trichlorobiphenyl-4-ol (compound 5) but this was eliminated when exposed to the S9 mix. 2,2('),3('),4,6-Pentachlorobiphenyl-3-ol (13) and 2('),3,3('),6-tetrachlorobiphenyl-4-ol (10) both showed weak estrogenicity in the absence of the S9 mix. The estrogenicity of compound (10) was enhanced 10-fold by exposure to S9 metabolic activation but that of compound (13) remained unchanged. 2('),4,5('),6-Tetrachlorobiphenyl-2-ol (6) showed strong thyroid hormonal activity (5% of that of T4) whereas 3('),4,6-trichlorobiphenyl-3-ol (4), compound (10) and 2,3('),4,5('),6-pentachlorobiphenyl-3-ol (14) showed moderate activity, and 2('),3,3('),5-tetrachlorobiphenyl-2-ol (8) and 3,3('),5,5('),6-pentachlorobiphenyl-2-ol (11) showed weak activity. The activity of (4) was eliminated by S9 metabolic activation whereas those of (6) and (14) were weakened and that of (10) remained unchanged.     

Comparison of PCDD/F and coplanar PCB concentrations in Japanese human adipose tissue collected in 1970-1971, 1994-1996 and 2000

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar biphenyls (Co-PCBs) were determined in Japanese human adipose tissues. Temporal trends were assessed by comparing data collected during 1970-1971, 1994-1996 and 2000. Mean TEQ levels of PCDD/Fs in human adipose tissue showed a significant decrease from 31.6 +/- 9.2 pg-TEQ/g fat wt in 1970-1971 to 11.9 +/- 7.4 pg-TEQ/g fat wt in 2000, and coplanar PCBs decreased from 35.4 +/- 21.9 pg-TEQ/g fat wt in 1970-1971 to 15.3 +/- 8.2 pg-TEQ/g fat wt in 2000. However, some PCB congener concentrations did not change during this time. A comparison of data using the latest PCB-TEQ showed no significant changes. Therefore, research on source characterization and monitoring of short-term temporal trends on these compounds should be carried out continuously.     

Dechlorination of hexachlorobiphenyl by using potassium-sodium alloy

2,2',4,4',5,5'-Hexachlorobiphenyl (HCB) was dechlorinated with potassium-sodium (K-Na) alloy under an inert gas atmosphere. Solvent effect was observed in the reaction. Dechlorination yields in benzene and cyclohexane were 99.9998%, and 99.99996%, respectively. The reaction was exothermic and proceeded at room temperature. In benzene, trace amounts of polychlorinated biphenyls (PCBs) as products by stepwise dechlorination and polychlorinated quarterphenyls as product of Wurtz-Fittig reaction were detected as reaction intermediate. Reaction products were biphenyl, cyclohexylbenzene, and dicyclohexyl. In cyclohexane, there were no products of Wurtz-Fittig reaction. Dechlorination at para-position preferred to that at ortho-position, judging from analysis of PCBs as intermediates of stepwise dechlorination.     

Environmental fate of pesticides used in Australian viticulture V. Behaviour of atrazine in the soils of the south Australian Riverland

The transport of the s‐triazine herbicide, atrazine, through the red, calcareous earth soils of the South Australian Riverland was investigated. Small, undisturbed soil cores were extracted from the inter‐row topsoil of a vineyard adjacent to the River Murray, approximately 10 km south‐west of Overland Corner, South Australia. The vines were grown in a deep (1–4 m) reddish brown, strongly alkaline, sandy loam with a low organic carbon content (<2%). Atrazine concentrations in the leachate were dependent on application rate and soil type. High application rates on subsoil gave high rates of leaching for a longer time compared to the same application rate on topsoil and/or lower application rates on either topsoil or subsoil. Overall, 37–65% of the applied atrazine was detected in the leachate from subsoil cores, 14–25% in topsoil core leachates. Small amounts of atrazine (< 10% of applied dose) were found only in the top 2 cm of the core profiles. The results suggest that this herbicide is somewhat mobile in such strongly alkaline, sandy loam soils and that the irrigated soils of this region are likely to be prone to leaching of atrazine, and therefore that groundwater supplies in this area may be at risk of contamination through use of triazine herbicides.     

Dissolution of polystyrene into cyclic monoterpenes present in tree essential oils

We examined dissolution of polystyrene (PS) into cyclic monoterpenes present in tree essential oils, in order to develop an environmentally friendly shrinking agent for expanded polystyrene. The relationship between the chemical structure of the monoterpenes and their dissolution power for PS was studied through the solubility parameter (δ) and apparent activation energy (E _a) for dissolution. (R)-Limonene and its structural isomers on a C=C bond have high solvent power for PS. This favorable solubility was explained by their solubility parameters. The occurrence of hydroxyl group in a solvent molecule, such as in terpinen-4-ol, reduced affinity for PS. Bicyclic monoterpenes and 1,8-cineole, which have sterically bulky structure, showed limited dissolution power even though they have solubility parameters similar to that of (R)-limonene. Their bulky structures would interfere with permeation of solvent into the PS matrix. Cyclic monoterpenes and PS were recovered almost quantitatively by simple steam distillation of the PS solution.     

Control of Mercury Emissions from a Municipal Solid Waste Incinerator in Japan

Abstract

The control of Hg emissions from a municipal solid waste incinerator (MSWI) is very important, because more than 78% of municipal solid waste (MSW) is incinerated. The Hg content of coal used in utility boilers is relatively low in Japan. In this study, recent trends in the Hg content of MSW in Japan and activated carbon (AC) injection as a control technology of Hg emission from an MSWI are discussed. The effect of AC injection on Hg removal from flue gas in an MSWI was investigated by pilot-scale experiments using a bag filter (BF). The injection of AC increases the Hg reduction ratio by 20–30% compared with cases without AC injection. The Hg reduction ratio increases as the flue gas temperature decreases. The Hg reduction ratio is closely related to the inlet Hg concentration and was expressed with a Langmuir-type adsorption isotherm.