Ambient Water Quality Guidelines for Manganese

Overview Report

Prepared pursuant to Section 2(e) of the
Environment Management Act, 1981

Original signed by Margaret Eckenfelder
Assistant Deputy Minister
Environment and Lands HQ Division
January, 2001

National Library of Canada Cataloguing in Publication Data
Nagpal, N. K.
Ambient water quality guidelines for manganese

Includes bibliographical references: p.
ISBN 0-7726-4444-6

1. Water quality - Standards - British Columbia.
2. Manganese - Environmental aspects - British Columbia.
I. British Columbia. Water Management Branch. II. Title.

TD227.B7N34 2001 363.739'462'09711 C2001-960006-2

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TABLE OF CONTENTS

Summary

Tables

• Table 1: Examples of the Recommended Guidelines to Protect Freshwater Aquatic Life from Toxic Effects of Manganese

Preface

Introduction

Recommended Guidelines

Application of the Guidelines

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Summary

This document is one in a series that establishes ambient water quality guidelines for British Columbia. It is primarily based on the thesis submitted by P. S. Reimer, Department of Chemical and Bio-Resource Engineering, University of British Columbia, Vancouver, BC, in partial fulfillment of requirements for the Master of Science degree. The report sets guidelines for manganese (Mn) to protect aquatic life in the freshwater environment only. The guidelines are summarized in Table 1. The Ministry of Environment, Lands and Parks (MELP) supported this work by providing:

1. data on manganese toxicity relevant to aquatic organisms found in British Columbia, and
2. professional guidance and review of the thesis report.

Manganese guidelines were not set for agricultural (irrigation and livestock watering), wildlife and industrial water uses, since suitable data documenting the effects of manganese for these uses were not available in the literature. Appropriate documentation by Health Canada should be referred to for details on guidelines for the protection of drinking and recreational (e.g., swimming) water uses. Health Canada recommended an aesthetic objective of 0.05 mg/L manganese in drinking water to protect against staining (e.g., plumbing), but deemed it unnecessary to provide guidance to protect from manganese toxicity in drinking and recreational waters.

Manganese, an essential trace element for aquatic and terrestrial biota, is only slightly to moderately toxic to aquatic organisms in excessive amounts. It is present in almost all organisms, and often ameliorates the hazard posed by other metals. Hence, most jurisdictions in the international arena have not promulgated manganese guidelines to protect freshwater and marine life. Nevertheless, manganese concentrations in the environment may be well above the aquatic toxicity levels in effluents originating from base and precious metal mines, municipal sewage and sludge and landfills. A more detailed discussion on water quality guidelines for manganese is presented in the main body of the report.

Manganese preferentially binds to particulate matter. Typically, 90% to 95% of the total waterborne manganese residue is associated with the particulate matter. However, soluble species of the metal are considered to be the most toxic as they are readily available for biological reactions. It is, therefore, recommended that the proposed guidelines should be interpreted in terms of the dissolved metal fraction when the total manganese concentration in the environment exceeds the guideline due to particulate matter and adverse effects due to manganese are not obvious.