Canadian Cataloguing in Publication Data

Swain, L. G. (Leslie Grant), 1950-
Second Report on chemical sensitivity of BC lakes to acidic inputs

ISBN 0-7726-0709-5

1.  Limnology - British Columbia.
2.  Acid pollution of rivers, lake, etc. - British Columbia.
I.  British Columbia. Ministry of Environment and Parks.
II. Title  III. Title: Chemical Sensitivity of BC lakes to acidic inputs.


QH106.2.B7S82 1987    551.48'2'09711    C87-092177-0

TABLE OF CONTENTS

• Canadian Cataloguing in Publication Data
• Abstract
• Figures
  • Figure 1 Approximate Locations of Lakes Sampled for Mapping Sensitivity.
  • Figure 2 Percentage of Species Able to Exist at Various Lake Acidity Levels.
  • Figure 3 Lake Acidity Levels in British Columbia.
  • Figure 4 Lakes with pH less than 6.0.
  • Figure 5 Lake Sensitivity to Acid Rain.
  • Figure 6 Distribution of Lakes in British Columbia by each Sensitivity Rating Characteristic (1977-1986).
  • Figure 7 Regional Boundaries of the Ministry of Environment.
  • Figure 8 Lake Sensitivity to Acid Inputs: Based on Calcium.
  • Figure 9 Lake Sensitivity to Acid Inputs: Based on Alkalinity.
  • Figure 10 Present Lake Acidity: Based on pH.
  • Figure 11 Sensitive Environments to Acidic Deposition.
• Tables
  • Table 1. Lake Sensitivity Characteristics: Vancouver Island Region
  • Table 2. Lake Sensitivity Characteristics: Lower Mainland Region
  • Table 3. Lake Sensitivity Characteristics: Southern Interior Region
  • Table 4. Lake Sensitivity Characteristics: Kootenay Region
  • Table 5. Lake Sensitivity Characteristics: Northern Region
• Acknowledgements
• Introduction
• Discussion
• References Cited

ABSTRACT

Information is also provided on calculated relationships between total dissolved solids and several characteristics. Relationships with a high level of confidence exist for calcium, inflection point alkalinity and alkalinity to pH 4.5.

ACKNOWLEDGEMENTS

Ms. L. Rounds typed several drafts of this report.

To these people goes the credit for any information presented herein. As author, I must take responsibility for any inaccuracies

INTRODUCTION

The purpose of this document is to provide information on the status of lakes in British Columbia with respect to acidic inputs. Acidic inputs do not originate necessarily as acid precipitation, but also can originate as acidic waste water effluents discharged from industrial operations.

The information in this document relates solely to lakes and does not reflect river water quality. The reasons for this are:

1. Rivers and streams can reflect recent events such as snowmelt. An accurate representation of the water quality of a river or stream is not possible unless a large number of samples are obtained in one season
2. Lakes provide a zone in a watershed where short-term events such as snowmelt can be averaged out. This reduces the necessity to collect samples as frequently as would be the case for rivers and streams
3. The water quality of rivers and streams can vary along their length more than lakes due to the heterogeneous geological nature of drainage basins

DISCUSSION

In British Columbia, lake sensitivity is determined from measurments of the alkalinity and/or calcium present. Measurements of these characteristics were made at the Environmental Laboratory of the Ministry of Environment and Parks in Vancouver. Alkalinity provides the most direct measurement of sensitivity of a lake to acidic inputs, since it measures the carbonate-bicarbonate buffering capacity. Thses anions generally are in equilibrium with calcium and magnesium cations. In British Columbia, the chemical sensitivity of lakes is determined according to the following criteria for alkalinity and calcium.

Using these criteria a lake sensitivity map for British Columbia was prepared using data collected from 1977 to 1983. The preparation of this map initially required that two sensitivity maps based on calcium and alkalinity measurements had to be prepared. The lake sensitivity map was produced by overlaying these calcium and alkalinity maps ( Figure 5). The final map depicts the most sensitive rating from either of the initial maps, i.e. and area of high sensitivity on either map became an area of high sensitivity on the final map, an area of moderate and low sensitivity on the initial two maps became an area of moderate sensitivity on the final map.

• Those with 0.0 to 2.49 mg/L alkalinity comprise 0.8%
• Those with 2.5 to 4.99 mg/L alkalinity comprise 4.7%
• Those with 5.0 to 7.49 mg/L alkalinity comprise 3.3%
• Those with 7.5 to 9.99 mg/L alkalinity comprise 3.3%

Other relationships which do not have the same confidence level are listed below. These are provided for the benefit of other researchers.

REFERENCES CITED

• Saskatchewan Research Council. 1982. Evaluation of the Status of Surface Water Sensitivity Mapping for Acidic Deposition in Western Canada. Prepared for the Technical Committee, Western Canada Long Range Transport of Atmospheric Pollutants by the Coordinating Committee on Surface Waters. SRC Publication No. C-805-11-E-82. February.