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Acid Deposition Effects on Geochemical Cycling and Biological Availability of Trace Elements . Subgroup on Metals of the Tn-Academy Committee on Acid Deposition Academia de la Investigacion Cientifica of Mexico Roval Society of Canada National Academy of Sciences of the United States of America NATIONAL ACADEMY PRESS Washington, D.C. 1985
NOTICE: This report is a result of a joint project of the U.S. National Academy of Sciences, the Royal Society of Canada, and the Academia de la Investigation Cientifica of Mexico. On behalf of the National Academy of Sciences, the project was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, National Academy of Engineering, and Institute of Medicine. The members of the committee responsible for this report were jointly chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by the National Academy of Sciences, the Royal Society of Canada, and the Academia de la Investigacion Cientifica of Mexico. . Printed in the United States of America
Tri-Academy Committee on Acid Deposition Jointly organized under the auspices of the National Academy of Sciences (NAB) of the United States of America, the Royal Society of Canada (RSC), and the Academia de la Investigation Cientificia (AIC) of Mexico Ellis Cowling, North Carolina State University, Cochairman for NAS Maxwell J. Dunbar, McGill University, Cochairman for RSC Alejandro Velasco Levy, Universidad Nacional Autonoma de Mexico, Cochairman for AIC Peter G. C. Campbell, Universite du Quebec* Cristina Cortinas de Nava, Ciodad Universitaria, Mexico City James N . Galloway, Univer s ity of Virg inia* Warren Godson, Atmosphere Environment Service, Canada Eville Gorham, University of Minnesota Wilmot Hess, National Center for Atmospheric Research, U.S.A. George M. Hidy, Environmental Research and Technology, Inc., U.S.A. Thomas Hutchinson, University of Toronto James R. Kramer, McMaster University Stephen Norton, University of Maine David W. Schindler, Freshwater Research Institute, Canada Pamela Stokes, University of Toronto* George Tomlinson II, Domtar Inc., Canada Carlos Vazquez Yanes, Universidad Nacional Autonoma de Mexico Gregory Wetstone, Environmental Law Institute, U.S.A.** Andrew Forester, Staff Officer (RSC) William M. Stigliani, Staff Officer (NAS) Myron F. Uman, Staff Officer (NAB) Lorenzo Uribe, Staff Officer (AIC) *Member of Subgroup on Metals. **Current address: Health and Environment Subcommittee, Congress of the United States of America. · · ~
PREFACE The Tri-Academy Committee on Acid Deposition was formed in 1981 to develop cooperative activities between the Royal Society of Canada, the Academia de la Investigation Cientificia of Mexico, and the National Academy of Sciences of the United States of America. The committee is charged with reviewing the adequacy of current and prospective research and activities related to solving environmental problems that result from acid deposition. The impetus for this report was the determination by the committee that the possible interaction between acid deposition and the natural cycling of trace metals is an area of particular interest and concern. The Subgroup on Metals was formed to address this topic in detail. Three members of the committee, Peter G. C. Campbell, Pamela M. Stokes, and James N. Galloway served on the ~ ~~ "~~-~ -- ~= ~ -ace-" Much of the staff subgroup. They are the authors of this report. _ _ support was provided bv William M. Stigliani of the u.S. National _ _= ~ ~ ~ _ _ _ _ , Academy of Sciences staff. The task of the subgroup was to examine possible interactions among the following phenomena: acid precipitation; the atmospheric deposition of trace metals; the geochemical cycling of both these deposited metals and those initially present in the geological substrate; the biological availability of these metals. Emphasis has been placed on atmospheric deposition of air pollutants {H2SO4, HNO3, metals) in areas remote from point sources. Effects on both terrestrial and aquatic ecosystems have been considered, again in regions affected by long-range atmospheric transport rather than in more heavily impacted areas close to pollution sources. Conclusions and recommendations for further research are presented at the end of this report. v
CONTENTS LIST OF FIGURES AND TABLES 1. INTRODUCTION 2. STATE OF RNC~LEDGE OF ME:TAL-pH-=OSYS=M TN=RACTIONS 3. CONCLUSIONS AND RECOMMENDATIONS REFERENCES APPENDIX: TABULATION OF STATE OF KNOWLEDGE ON ME:TAL-pH ECOSYSTEM INTERACTIONS FOR SPECIFIC METALS vii · · ~ V11 1 1 4 44 47 ; 65
LIST FIGURES AND TABLES Figure 1.1 Figure 2.1 Figure 2.2 Table 2.1 Table 2 .2 Table 2.3 Table 2 .4 Table 2 .5 Framework of relevant questions pertaining to trace metals Typical pH adsorption curve for divalent cations on hydrous metal oxides (pH50 values may range from about 3 to 8) Relationship between pa and total (unfiltered) Al concentrations in Swedish lakes Median Concentrations of Metals in Total Wet Deposition ~ ug/~) Calculated Speciation of Dissolved Trace Metals in a Typical Rainwater (pa 4.14, pC1 4.88) Mean Values of Data Reported from All Seasons for Dry Fraction of Total Deposition Adsorption of Trace Metals on Colloidal Metal Hydroxides Possible Physicochemical Forms of Trace Metals in Natural Waters ~ 3 10 13 6 7 8 11 18 Table 2.6 Ion-Exchangeable Metal as a Proportion of Total Filterable Metal (<0.4 um) in Various Fresh Waters 20 Table 2.7 Table 2.8 Table 2.9 Trace Metals Exhibiting Increases in Concentration in Response to Acidification Effect of Acidification on the Calculated Speciation of Dissolved Trace Metals in a Typical Surface Water from the Canadian Shield Calculated "Inherent Toxicities. of Some Metals viii 23 24 29
Table 2.10 Table 2.11 Table 2.12 Table 2 .13 Table 2. ~ 4 Table A. 1 Table A.2 Values of peso for the Adsorption of Trace Metals on Natural Sediments Influence of pa on the Speciation of Sediment-Bound Trace Metals Trace Metals Released from Sediments in Response to Acidification Summary of Answers to Framework Questions Interactions Between Atmospheric Deposition and Metal Biogeochemistry Aluminum Arsenic Beryllium 33 34 35 40 42 66 67 68 Table A.4 Cadmium 69 Table A.5 Cobalt 70 Table A.6 Copper 71 Table A.7 Lead 72 Table A.8 Manganese 73 Table A.9 Mercury 74 Table A.10 Molybdenum 75 Table A.ll Nickel Table A.12 Selenium Table A.13 Silver Table A.14 Tellurium Table A.15 Thallium Table A.16 Tin Table A.17 Vanadium Table A. 18 Zinc 76 77 78 79 80 81 82 83 ix