Aquatic Plant Science

The science of submerged aquatic plants in the aquarium hobby


    Hard water reduces heavy metal toxicity of fish

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    Lawrence So

    Posts : 21
    Join date : 2016-07-20
    Location : San Francisco, CA

    Hard water reduces heavy metal toxicity of fish

    Post by Lawrence So on Tue Aug 02, 2016 12:11 pm

    The aim of this study was to utilize static test for examining the acute toxicity of two essential elements, Cu and Zn, to a native fish, Capoeta fusca, by static bioassay. The acute toxicity of two heavy metals to C. fusca was determined in the soft, hard and very hard water (40, 150 and 380 mg/L as CaCO3). Results showed that toxicity of Cu and Zn decreased with increasing water hardness, so that water hardness had a significant effect on Cu and Zn toxicity on fish. Copper and Zn were more toxic in the soft water than in the hard water. The 96-hour lethal concentration for 50% (LC50) values for C. fusca were lower in the soft water compared with the hard and very hard water. The 96-hour LC50 for Cu at the soft, hard and very hard water was found to be 1.1, 5.4 and 7.5 mg/L, respectively, while the 96-hour LC50 for Zn at the soft, hard and very hard water was found to be 13.7, 74.4 and 102.9 mg/L, respectively.
    http://m.tih.sagepub.com/content/26/6/361.short

    Here's experimental evidence showing the lethal effects, LC50, of copper and zinc under varying harnesses of water.  Note the emphasis that this was about lethal effects, not sub-lethal effects.  Sub-lethal effects are much more insidious and impairs physiological function of organs, especially long-term exposure.

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