Effects of Acid pH on Embryonic and Juvenile Freshwater Fish

The effects of sulfuric acid on embryos, larvae, and juvenile fish were examined using standard bioassay techniques, as well as in a preference/ avoidance behavioral test. The objectives were to compare the sensitivities of the various ages of fish to acid and to assess the use of the behavioral test in a hazard assessment program. In an 8-day static renewal bioassay, embryos and larvae of the fathead minnow were not affected at a pH of 4.92 and above, but pH 3.57 produced complete mortality prior to hatching. In 96- hr acute bioassays, 8-wk juvenile fathead minnows survived 100% at pH\u27s of 5.02 to 7.38, while complete mortality occurred at pH\u27s below 3.90. At pH 4.29, only 15% of the population survived. Similar results were obtained with 12-wk animals. Juvenile bluegill sunfish (8 wk) and fathead minnows (6 and 14 wk) also were exposed to various concentrations of sulfuric acid in a preference/avoidance bioassay. Both 14-wk fathead minnows and 8-wk bluegill sunfish avoided acid pH\u27s below pH 6.0, while the 6-wk fathead minnows avoided all acid levels tested (i.e., pH 6.19 and below). Therefore, the 6-wk fathead minnows appeared to be the most sensitive to acid stress. Based on these findings, juvenile fish, given a choice, would tend to avoid acid levels that might not prove lethal to them. Therefore, the preference/ avoidance bioassay should not be used alone but could be an important tool in evaluating sublethal effects in a multistage hazard assessment program

Thermal Radiation From Carbon Nanotube in Terahertz Range

The thermal radiation from an isolated finite-length carbon nanotube (CNT) is theoretically investigated both in near- and far-field zones. The formation of the discrete spectrum in metallic CNTs in the terahertz range is demonstrated due to the reflection of strongly slowed-down surface-plasmon modes from CNT ends. The effect does not appear in semiconductor CNTs. The concept of CNT as a thermal nanoantenna is proposed.Comment: 5 pages, 3 figure