Ecological Effects of Benzyl Chloride on Different Korean Aquatic Indigenous Species Using an Artificial Stream Mesocosm Simulating a Chemical Spill

In this study, an artificial stream mesocosm consisting of a head tank, faster-flowing riffle section, gravel section, pool section, lower-run section, and tail tank was installed to simulate a chemical spill in a river. The responses of freshwater periphyton algae, crustacea (Moina macrocopa), freshwater worm (Limnodrilus hoffmeisteri), benthic midge (Glyptotendipes tokunagai), and fish (Zacco platypus and Aphyocypris chinensis) were observed after exposure to benzyl chloride (classified as an accident preparedness substance, APS) at concentrations of 1, 2, and 4 µL/L for 22.5 h. Higher concentrations increased the inhibition (photosynthetic efficiency decrease) of periphyton algae and the mortality of M. macrocopa, whereas the reproduction of the female cladoceran decreased in the 4 µL/L treatment. Mortality of fish did not occur or was lower (≤20%) at all concentrations; however, toxic symptoms were observed for some time after chemical exposure termination and later, symptoms receded. G. tokunagai mortality increased at all concentrations except the control after seven days, and no significant toxic effects were observed in L. hoffmeisteri. The hazardous concentration of benzyl chloride was calculated as 94 µg/L. This study showed the different sensitivities of each species to benzyl chloride. The findings can assist in environmental risk assessment of APSs after chemical spills to protect Korean aquatic species.

APPLICATION OF CONTROLLED SOURCE AUDIO MAGNETOTELLURIC (CSAMT) AT GEOTHERMAL

<p class="abstrak">CSAMT or Controlled Source Audio-Magnetotelluric is one of the Geophysics methods to determine the resistivity of rock under earth surface. CSAMT method utilizes artificial stream and injected into the ground, the frequency of artificial sources ranging from 0.1 Hz to 10 kHz, CSAMT data source effect correction is inverted. From the inversion results showed that there is a layer having resistivity values ranged between 2.5 Ω.m – 15 Ω.m, which is interpreted that the layer is clay.</p><p class="abstrak"><span lang="EN-US"><br /></span></p>

A simple, inexpensive artificial stream for rearing Ephemeroptera from sandy substrates

We describe a simple, inexpensive artificial stream to rear mayflies from sandy bottom streams. It consisted of a 151 L tub containing sand and water from a local stream. A small submersible pump circulated the water and netting was placed over the tub to collect adults. The stream was operated in a heated greenhouse. This artificial stream was remarkably productive. We collected over 2100 adult mayflies representing 6 genera along with several Trichoptera and Diptera adults. This stream was productive for 55 weeks with minimal maintenance.