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- Table 15. Summary of aquatic phytotoxicity data for manganese
- Table 16. Summary of freshwater invertebrate toxicity data for manganese
- Table 17. Summary of saltwater/marine invertebrate toxicity data for Manganese
m.3Aquatic plantsm.3.1MMTNo information was available on the toxicity of MMT to aquatic plants. m.3.2ManganeseManganese is widely distributed in the earth’s crust, most commonly as MnO2. It is present in natural waters in suspended form (similar to iron) although soluble forms may persist at low pH or low dissolved oxygen (ANZECC and ARMCANZ, 2000). The information presented below indicate that Mn is slightly to moderately toxic to freshwater and marine aquatic plants with acute LC(EC)50 values in the range of 4.98 mg/L or greater (Mensink et al., 1995). Freshwater aquatic toxicity data for Mn were available for 7 aquatic plant species including 2 macrophytes and 5 species of algae. The data are summarised in Table 15.
Two studies have investigated the effects of Mn to marine diatoms (Fisher and Jones, 1981, as cited by USEPA, 2000; Rosko and Rachlin, 1975, as cited by USEPA, 2000). The 96-hour EC50 (growth) values for diatoms (Asterionella japonica and Nitzschia closterium) range from 25.7 to 53.8 mg/L. m.4Aquatic invertebratesm.4.1MMTThe acute (48 hour) toxicity of MMT (95% purity) was studied in cultured neonates (<24 hours old) of the freshwater crustacean Daphnia magna (waterfleas) under static test conditions (Analytical Bio-chemistry Laboratories, Inc., 1990). The study was undertaken with measured MMT concentrations (means) of 0, 0.29, 0.65, 1.0, 2.0, and 3.5 mg/L. Measured concentrations were less than estimated nominal concentrations, presumably due to photodegradation of MMT. Test dilution water had hardness 172 mg/L (as CaCO3), alkalinity 192 mg/L (as CaCO3), pH 7.9, and conductivity 325 Mhos/cm. The 48-hour EC50 was 0.83 mg/L (95% C.I. 0.70 to 0.99 mg/L). The 4-hour and 24-hour EC50 were 0.87 and 0.94 mg/L, respectively. The 48-hour NOEL, based on the absence of immobility and abnormal effects, was 0.29 mg/L. Abnormal effects including immobility and surfacing were observed with the mean measured MMT concentrations of 0.65 mg/L and greater under test concentrations. Acknowledging data limitations, these results for Daphnia magna suggest that MMT may be considered highly toxic to aquatic invertebrates, with acute LC(EC)50 values in the range of <1 mg/L (Mensink et al., 1995). m.4.2ManganeseThe information presented below indicates that Mn is slightly to moderately toxic to freshwater and marine invertebrates with acute and chronic LC(EC)50 values in the range of 1 to 10 mg/L (Mensink et al., 1995). Manganese is a neurotoxin and can block the release of neurotransmitters such as acetylcholine, while inhibiting acetylcholine esterase activity (Skukla and Singhal, 1984, as cited by MacDonald et al., 1988). Acute and chronic toxicity data for Mn are available for several species of freshwater invertebrates with acute and chronic LC50 values ranging from 12.6 and 9 mg/L, respectively. Sublethal effects including intoxication and aberrant reproduction have been recorded above 4.7 mg/L. The data are summarised in Table 16.
a. Maximum acceptable threshold concentration (MATC) is a hypothetical threshold concentration that is the geometric mean between the NOEC and LOEC concentration. Manganese toxicity data are available for several species of marine invertebrates with acute toxicity (mortality) in the range of between 16 to 75 mg/L and chronic EC50 values in the range of 1 to 10 mg/L (refer Table 17). Table 17. Summary of saltwater/marine invertebrate toxicity data for Manganese
* ANZECC and ARMCANZ (2000) noted the apparent spurious data generated in this study for lower tested concentrations of manganese. MacDonald et al. (1988) noted that embryos of the crab species Cancer anthonyi live on the outside of the adult crab and may receive a higher exposure than many other aquatic organisms, explaining the higher sensitivity compared to other aquatic organisms. MacDonald et al. (1988) suggest that adverse effects of metals such as Mn may not be expressed within the typical time frame of standard toxicity tests (e.g. 96 hours), and that effects of Mn may not be fully expressed until at least 120 hours. However as they indicated, the increased rate of effects they noted at 120 hours in the toxicity test coincided with a peak in metamorphosis and hatching of viable embryos, which may be a more sensitive life stage. Other confounding factors in the tests, such as disease, cannot be excluded. Eggs of the marine crab Carcius maenas can accumulate Mn during ovogenesis (Martin, 1976a, as cited in MacDonald et al., 1988). Further, eggs of the marine crab Cancer irroratus can accumulate Mn following exclusion, due to their selective adsorption to the chitinous vitelline membrane (Martin, 1976b, as cited in MacDonald et al., 1988). Bioconcentration of Mn by these crab species, may explain the high sensitivity of these species to Mn relative to other marine organisms (e.g. Rao and Saxema, 1981, as cited in MacDonald et al., 1988; Morgan et al., 1986, as cited in USEPA, 2000). Watling (1983) investigated the effects of Mn on settlement of the oyster Crassostrea gigas, finding no effects on larval settlement or larval behaviour (as evidenced by foot extension and crawling movement) when exposed to 0.02 mg/L. This was the highest concentration tested. The author suggested that minor effects in growth of 51-day old young (spats) may have been evident following 14-days exposure to Mn at the lowest concentration tested (i.e. 0.01 mg/L). However, further testing would be required to verify this hypothesis, and spat growth recovered following removal to clean seawater for 14 days. Directory: data -> assets -> word doc -> 0020 word doc -> Commonwealth of Australia 2002 word doc -> Commonwealth of Australia 2000 word doc -> Rail safety news issue 6 – October 2011 word doc -> Review of Multiple Chemical Sensitivity: Identifying word doc -> Board Endorsed October 2009 amended 13-09-11 with extra units 0020 -> Rail safety news issue 5 may 2011 0020 -> The arts ripple effect: valuing the arts in communities 0020 -> Monash university accident research centre report documentation page 0020 -> Section 1: Working with the Government and the Parliament 6 1Summary 6 0020 -> Bachelor of Computer Science and Bachelor of Economics (61010) Applicability of the general provisions 11 47. 1 Download 0.91 Mb. Share with your friends:
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