Japan Geoscience Union Meeting 2018

Presentation information

[EE] Evening Poster

A (Atmospheric and Hydrospheric Sciences) » A-HW Hydrology & Water Environment

[A-HW20] Materials transport and nutrient cycles in watersheds; Human and climate impacts

Mon. May 21, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Mitsuyo Saito(Graduate School of Environmental and Life Science, Okayama University), Shin-ichi Onodera(Graduate School of Integrated and Arts Sciences, Hiroshima University), Takahiro Hosono(熊本大学大学院先導機構, 共同), Adina Paytan(University of California Santa Cruz)

[AHW20-P24] Feasibility study for toxicity evaluation of river sediments by bioassay using Chironomus yoshimatsui

*Shinji Nakaya1, Kaito Misawa1, Kazunori Okajima1 (1.Department of Water Environment and Civil Engineering, Faculty of Engineering, Shinshu University)

Keywords:river sediment, bioassay, biologic toxicity

Huge numbers of anthropogenic toxic chemicals are newly produced every year and some chemicals are leaking into environment. River sediment is one of the largest sink of toxic chemicals. The toxic chemicals in river sediments are mobile with sediments via river flow and can spread toward seabed. However, there are too many chemicals produced annually to experimentally evaluate the risk of each chemical.
In this study, we measured the hatchability of Chironomus yoshimatsui and several toxic trace elements, which is extracted by batch test based on Environment Agency notification No.46 in 1991, in the river sediment and factory waste sludge samples to evaluate the biologic toxicity. Although the concentration of each toxic trace element in the samples is under the level specified in the environmental quality standards for water, the hatchability was zero or nearly zero for several river sediments and factory waste sludge. This indicates that the hatchability works as an indicator to biologic risk. The hatching rate also tends to decrease with the increase of arsenic in samples. Our study supports the toxicity evaluation of river sediments by bioassay using Chironomus yoshimatsui is feasible for the unknown chemicals and/or the combination of known toxic chemicals in a river sediment.