Springer Theses Impacts of Selenium on the Biogeochemical Cycles of Mercury in Terrestrial Ecosystems in Mercury Mining Areas Bearbeitet von Hua Zhang 1. Auflage 2014. Buch. xxii, 193 S. Hardcover ISBN 978 3 642 54918 2 Format (B x L): 15,5 x 23,5 cm Gewicht: 491 g Weitere Fachgebiete > Geologie, Geographie, Klima, Umwelt > Geologie und Nachbarwissenschaften > Geochemie Zu Leseprobe schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, ebooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte.
Contents Part I Introduction 1 Research Background.... 3 1.1 General Background............................. 3 1.1.1 Mercury Pollution is One of China s Major Environmental Problems.................... 3 1.1.2 SINOMER Project........................ 4 1.2 Physical and Chemical Properties of Mercury and Selenium.................................. 5 1.2.1 Physical and Chemical Properties of Mercury..... 5 1.2.2 Physical and Chemical Properties of Selenium..... 7 1.3 Environmental Toxicology of Mercury and Selenium...... 7 1.3.1 Toxicity and Health Risks of Mercury Exposure... 7 1.3.2 Toxicity and Health Benefits/Risks of Selenium Exposure...................... 11 1.4 Evidence for Topic Selection....................... 12 1.4.1 Selenium is a Natural Mercury Antagonist....... 12 1.4.2 Selenium Pollution in Hg Mining Areas must be Considered....................... 12 References......................................... 14 2 Advances in Research on the Mechanisms of Selenium Mercury Interactions and Health Risk Assessment.... 17 2.1 Selenium Mercury Interactions and Their Mechanisms in Aquatic Ecosystems........................... 18 2.2 Selenium Mercury Interactions and Their Mechanisms in Terrestrial Ecosystems.......................... 20 2.3 Mechanisms of Selenium Mercury Interactions in Mammals (and Humans)........................ 22 2.3.1 Protective Effects of Selenium Against Mercury Toxicity and the Mechanisms Thereof........... 22 2.3.2 Implications of the Physiological Significance and Metabolic Processes of Selenium for the Toxicity of Mercury Exposure........... 26 xiii
xiv Contents 2.4 New Model for the Assessment of the Health Risks of Mercury and a Relevant Proposal.................. 27 References......................................... 30 3 Research Subject, Methods and Significance... 35 3.1 Research Subject............................... 35 3.2 Methods..................................... 35 3.2.1 Sample Collection and Preparation............. 35 3.2.2 Analytical Method........................ 39 3.3 Significance of this Study......................... 44 References......................................... 44 4 Overview of the Study Area (Wanshan)... 47 4.1 Study Area.................................... 47 4.2 Overview of Mine Area........................... 47 4.3 Geomorphology and Climate....................... 49 4.4 Water System in the Mine Area..................... 50 4.5 Agriculture and Population in the Mine Area............ 50 4.6 Geology of the Area............................. 51 References......................................... 51 Part II Biogeochemical Cycles of Mercury and Selenium and Their Interactions in River System 5 Biogeochemical Cycles of Mercury in River System.... 55 5.1 Speciation, Tempo-Spatial Distribution and Migration of Total Mercury............................... 55 5.1.1 Total Mercury........................... 55 5.1.2 Particulate Mercury, Total Suspended Solid, SO 2-4 and Ca 2 +... 64 5.1.3 Dissolved Mercury........................ 66 5.1.4 Reactive Mercury......................... 67 5.2 Speciation, Tempo-Spatial Distribution and Migration of Methylmercury............................... 68 5.2.1 Unfiltered Methylmercury................... 68 5.2.2 Ratio of Methylmercury to Total Mercury (%MeHg).............................. 75 5.2.3 Dissolved- and Particulate- Methylmercury....... 76 5.3 Chapter Summary............................... 79 5.3.1 Total Mercury........................... 79 5.3.2 Methylmercury........................... 80 References......................................... 80
Contents xv 6 Biogeochemical Cycles of Selenium in River System... 83 6.1 Distribution, Source and Migration of Dissolved Total Selenium................................. 84 6.1.1 The Regional Distribution in Surface Water....... 84 6.1.2 Potential Sources......................... 84 6.1.3 The Local Background Concentrations.......... 88 6.1.4 Comparison with Other Regions............... 88 6.1.5 Relationship with Sulfate, ph, and DOC......... 89 6.2 Distribution and Migration Characteristics of Selenium Speciation........................... 90 6.2.1 Se(VI)................................. 90 6.2.2 Se(IV)................................. 92 6.2.3 Se(org)................................ 93 6.3 Risk Consideration.............................. 93 6.3.1 River Water............................. 93 6.3.2 Spring Water............................ 94 6.4 Chapter Summary............................... 95 References......................................... 95 7 Interactions of Mercury and Selenium in River System... 99 References......................................... 101 Part III Biogeochemical Cycles of Mercury and Selenium and Their Interactions in Soil-Rice System 8 Biogeochemical Cycles of Mercury in Soil-Rice System... 105 8.1 Mercury in Paddy Soil........................... 105 8.2 Mercury in Rice Grain........................... 106 8.3 Relationship Between Mercury in Rice and in Soil........ 107 8.4 Mercury Distribution in Different Parts of Rice.......... 113 8.5 Chapter Summary............................... 114 References......................................... 115 9 Biogeochemical Cycles of Selenium in Soil-Rice System... 117 9.1 Selenium in Soil................................ 118 9.2 Selenium in Rice Grain........................... 122 9.3 Relationship Between Selenium in Rice and in Soil....... 123 9.4 Selenium Distribution in Different Parts of Rice.......... 125 9.5 Fractionation of the Selenium in Soil................. 125 9.5.1 Water-Soluble Selenium.................... 125 9.5.2 Ligand-Exchangeable Selenium............... 127
xvi Contents 9.5.3 Organic-Bound Selenium.................... 128 9.5.4 Fe/Mn/Al Oxide-, Amorphous Material-, Hydrate- and Carbonate-Bound Selenium........ 129 9.5.5 Sulfide-Bound Selenium.................... 129 9.5.6 Residual-Bound Selenium................... 130 9.6 Chapter Summary............................... 130 References......................................... 131 10 Interactions of Mercury and Selenium in Soil-Rice System... 135 10.1 Selenium Levels Versus Mercury Levels in Grains........ 135 10.2 Selenium Levels Versus Mercury Levels in Soil.......... 137 10.3 Selenium Translocation Versus Mercury Translocation in Soil-Rice System............................. 137 10.4 Distribution Pattern of Selenium Versus that of Mercury in Different Parts of Rice......................... 137 10.5 Possible Mechanisms of Formation of Hg Se Complex in Rhizosphere/Root............................. 140 10.6 Suppression Effect of Selenium on Uptake and Translocation of Mercury in Rice................. 141 10.7 Impacts of Mercury on the Bioavailability of Selenium in Paddy Soil.................................. 145 10.8 Chapter Summary............................... 146 References......................................... 147 Part IV Health Risk Assessment for Human Exposure to Mercury and Selenium 11 Health Risk Assessment for Human Exposure to Mercury... 153 11.1 Calculation of Probable Daily Intake.................. 153 11.2 Mercury Levels in Different Exposure Media............ 155 11.3 Probable Daily Intake Levels....................... 155 11.4 Contributions to Mercury Exposure form Different Media... 156 11.5 Risk Considerations............................. 156 11.6 General Characteristics of Mercury Exposure............ 158 11.7 Food Consumption Advisories...................... 160 11.8 Percentage of Total Population Under Potential Health Risk................................... 161 11.9 Comments on Criteria of Mercury Risk Assessment....... 161 11.10 Chapter Summary............................... 162 References......................................... 163
Contents xvii 12 Health Risk Assessment for Human Exposure to Selenium.... 167 12.1 Calculation of Probable Daily Intake.................. 168 12.2 Selenium Levels in Different Exposure Media........... 169 12.3 Probable Daily Intake Levels....................... 169 12.4 Contributions to Selenium Exposure form Different Media............................ 169 12.5 Risk Considerations............................. 170 12.6 Chapter Summary............................... 171 References......................................... 171 13 Health Risk Assessment for Human Exposure of Mercury and Selenium Considering Selenium Mercury Interactions... 173 13.1 Proposal for a New Criterion....................... 176 13.2 Comparison of Different Criteria.................... 177 13.2.1 Scenario I, Criteria Considering Only Mercury.... 177 13.2.2 Scenario II, Criteria Considering Only Selenium... 179 13.2.3 Scenario III, Criteria Considering Mercury and Selenium Independently................. 181 13.2.4 Scenario IV, Criteria Considering Selenium Mercury Interactions............................. 182 13.3 Implications................................... 183 13.4 Chapter Summary............................... 184 References......................................... 185 Part V Conclusions and Prospect 14 Conclusions... 189 14.1 River System.................................. 190 14.2 Rice-Soil System............................... 190 14.3 Risk Considerations............................. 191 15 Research Needs and Future Outlook... 193
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