Manganese in freshwater and marine water

​​​Toxicant default guideline values for protecting aquatic ecosystems

October 2000

Extracted from Section 8.3.7 ‘Detailed descriptions of chemicals’ of the ANZECC & ARMCANZ (2000) guidelines.

The default guideline values (previously known as ‘trigger values’) and associated information in this technical brief should be used in accordance with the detailed guidance provided in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality.

Description of chemical

Manganese is commonly used in steel alloys and dry cell batteries as well as in paints, inks, glass, ceramics, fireworks and fertilisers (CCREM 1987). It is a common constituent of discharges from mining and smelting activities (Stubblefield et al. 1997). It is widely distributed in the earth’s crust, most commonly as MnO2. The current analytical practical quantitation limit (PQL) for manganese is 0.1 µg/L in fresh water and 2 µg/L in marine water (NSW EPA 2000).

Manganese is an essential trace element for microorganisms, plants and animals (CCREM 1987) and can be bioconcentrated up to four orders of magnitude, possibly to facilitate essential uses. It is present in natural waters in suspended form (similar to iron) although soluble forms may persist at low pH or low DO. Its toxicity is low compared to other trace metals and toxicity to brown trout Salmo trutta decreased significantly with increasing hardness (Stubblefield et al. 1997).

Freshwater guideline

Chronic data were available for manganese on only three taxonomic groups, so these data could only be used to derive an interim figure. More recent data (Stubblefield et al. 1997) determined an early life-stage IC25 to brown trout S. trutta of 4.67 mg/L at 30 mg/L hardness (CaCO3) and 8.68 mg/L at 450 mg/L hardness. It was preferred to use the acute data to derive a moderate reliability trigger value. Freshwater data (mg/L) were as follows (pH range 6.75 to 8.4):

Fish: three species, 48 to 96-hour LC50, 33.8 to 4540.0 mg/L (i.e. x 1000 µg/L); Chronic 28-day no observed effect concentration (NOEC) for additional species, Pimephales promelas, 1270 to 9990 µg/L (growth and mortality).

Amphibian: one species, Microhyla ornata, 2 to 4-day LC50, 14.3 to 16.6 mg/L.

Crustaceans: five species, 48 to 96-hour LC50/EC50, 4.7 mg/L (Daphnia magna) to 771 mg/L (Asellus aquaticus). An additional species, a harpacticoid copepod, had a 48-hour LC50 of 54 µg/L (0.054 mg/L), but this did not satisfy screening requirements.

Annelid: one species, Tubifex tubifex, 48 to 96-hour LC50, 171 to 208 mg/L.

Algae: one species, Chlorella vulgaris, NOEC, population growth, 4500 µg/L (4.5 mg/L).

Macrophyte: one species, Lemna minor, 96-hour EC50, growth, 32 mg/L.

A freshwater moderate reliability trigger value of 1900 µg/L was calculated for manganese using the statistical distribution method with 95% protection and an acute-to-chronic ratio (ACR) of 9.1.

Marine guideline

Marine data were available for only three taxonomic groups, and this did not include fish:

Crustaceans: two species, 10 µg/L (crab, 7-day lowest observed effect concentration [LOEC], mort.) to 70,000 µg/L. The low figure appears anomalous and needs to be checked.

Mollusc: one species, 48-hour LC50, 16,000 µg/L.

Algae: two species, a figure of 1500 µg/L for photosynthesis (EC50) is not suitable for use, 96-hour EC50, growth, 25,700 to 53,800 µg/L.

The marine dataset was more limited and there were some anomalies that may need to be checked. The outlying crab data and the photosynthesis EC50 for the alga were not used.

The marine dataset was more limited and there were some anomalies that may need to be checked. A marine low reliability trigger value at 80 µg/L was derived for manganese from the mollusc figure using an assessment factor (AF) of 200. This should only be used as an indicative interim working level.


ANZECC & ARMCANZ 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

CCREM 1987. Canadian water quality guidelines. Canadian Council of Resource and Environment Ministers, Ontario.

NSW EPA 2000. Analytical Chemistry Section, Table of Trigger Values 20 March 2000, LD33/11, Lidcombe, NSW.

Stubblefield WA, Brinkman SE, Davies PH, Garrison TD, Hockett JR & McIntyre MW 1997. Effects of water hardness on the toxicity of manganese to developing brown trout (Salmo trutta). Environmental Toxicology and Chemistry 16, 2082–2089.