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  1. Introduction Bruce Herbert Geology & Geophysics

  2. What is Environmental Geochemistry?

  3. Definition of Environmental Geology • Environmental geology applies geologic information to the solution, prediction and study of geologic problems such as: • Natural hazards: Floods, volcanic eruptions, earthquakes and tsunamis, and mass wasting events • Landscape evaluation: Land-use planning & siting critical facilities • Environmental quality and remediation: Risk assessment of contaminants in the environment, waste disposal, and remediation • Earth materials: Evaluation of mineral, petroleum, and water resources & engineering aspects of Earth materials.

  4. Scientific American: In developing countries, waterborne and sanitation-related diseases kill well over three million annually and disable hundreds of millions more, most of them younger than five years of age. The map shows the percent of urban populations with access to safe drinking water. Around the world a billion people lack access to safe water, and 1.8 billion do not have adequate sanitary facilities. Access to Clean Drinking Water

  5. Anthropogenic Compounds Figure 1.1 Global increase in synthetic organic production since 1930 (taken from Schwarzenbach et al., 1993)

  6. Anthropogenic Compounds Figure 1.2 Production and accumulation of DDT (taken from Schwarzenbach et al., 1993)

  7. Tenets of Environmental Geology Environmental geochemistry adapts the Concept of Uniformitarism to the prediction of important geologic processes that can affect living organisms and to the solution of environmental problems. • Modified Concept of Uniformitarism: the same Earth processes that are operating today, also operated in the past. Geologic processes that occurred in the recent past are our best indications of geologic processes that will happen in the future. • "The recent past may be the key to the near future" • An understanding of past geologic processes, scale of their effects, and the rates of their occurrences, allows environmental geologists to predict future occurrence and potential effects.

  8. Environmental Issues and Human Society • Currently, the expanding world population requires more resources; faces increasing losses from natural hazards; and contributes to growing pollution of the air, water, and land. • The activities of humans and their consequences are now comparable in magnitudes and rates as perturbations of the Earth's environment to many natural processes. • Many of these human perturbations are not beneficial to life on the planet. Committee on Status and Research Objectives in the Solid-Earth Sciences: A Critical Assessment (National Research Council). 1993. Solid-Earth Sciences & Society. National Academy Press. Washington, DC. 346 p.

  9. Environmental Issues and Human Society • Human societies face momentous decisions concerning their control of many future activities that require understanding the Earth. • The rates of changes have become so rapid that these issues cannot be ignored any longer if the Earth is to be managed as a sustainable habitat. • To accomplish sustainability will require all of our scientific understanding of the natural materials and processes, particularly the material and energy transfers linking the geosphere, hydrosphere, atmosphere, and biosphere. • Life prospers or fails at the surface of the Earth where these environments intersect Committee on Status and Research Objectives in the Solid-Earth Sciences: A Critical Assessment (National Research Council). 1993. Solid-Earth Sciences & Society. National Academy Press. Washington, DC. 346 p.

  10. Scale of Environmental Problems An understanding of past geologic processes, scale of their effects, and the rates of their occurrences, allows Environmental geologists to predict future occurrence and potential effects. • Given the size of the planet as well as its age (4.5 billion years), most geologic processes occur outside human experience • Scale denotes the resolution in the range of a measure quantity • Geologic processes occur at very large ranges of spatial scale, from planet-wide processes to chemical reactions on the surface of a mineral • Likewise, geologic processes occur at very large ranges of temporal scale. They can be very fast (occur over short time spans) such as earthquakes or they can occur over very long times, such as the erosion of mountains

  11. Spatial & Temporal Scales of Geologic Processes

  12. Observations and Scientific Investigations Geologic evidence for processes occurring at different time and space scales: How do we collect data? • Laboratory experiments • Point measurements over small areas such as aquifers • Large number of point measurements and remote sensing provides information over large spatial scales • Study the geologic record, which is the vast amount of rock that makes up the outermost layer of the Earth called the crust. Information on the processes that shaped the Earth is reflected in the properties of the rock layers that make up the geologic record • It is easier to measure over space than time

  13. Significant Scales of Time and Space • Human experience limits the geologic processes we can directly experience. • Due to technological advances in the 20th century, we can directly experience geologic events occurring all over Earth, as well as many nearby celestial bodies • The development of written history has extended our ability to experience geologic events from the lifetime of an individual (or several if oral histories are preserved, to several thousands of years. This, of course, is a very short time span compared to the great age of the Earth • Environmentally-significant geologic processes are mainly those that occurred over the last 100 thousand years BP or later

  14. Perturbed Environments

  15. Geochemical Perturbations of the Near-Surface Environment Four important characteristics distinguish geochemical perturbations of near-surface environments such as soils, aquifers, wetlands, and estuaries. • The degree of localization of a source is described as point or nonpoint sources • The loading history describes the variation over time in the amount of the perturbation • Source of geochemical perturbation: contaminant type • Nature of geologic system

  16. Geochemical Perturbations: Localization The degree of localization of a source is described as point or nonpoint sources. • Point source: a source characterized by the presence of an identifiable, small scale source • Examples: leaking storage tank, disposal pond, or a sanitary landfill • Nonpoint source: a larger-scale, relatively diffuse contamination originating from many smaller sources, whose location is often poorly known • Examples: agricultural pesticides and herbicides, nitrates from household disposal systems, salt from deicing highways, and acid rain

  17. Geochemical Perturbations: Loading History The pollutant loading history describes how the concentration or rate of production of a chemical varies with time • Pulse loading: short-term loading at fixed concentrations. Example: a spill • Continuous source loading: fixed concentrations that remain constant over time • Variable source loading: concentrations vary over time. This is the most common case • Example: a storage pond where chemical wastes are sporadically added

  18. Geochemical Perturbations: Contaminant Type Domenico and Schwartz (1990) grouped contaminants into six categories based upon classes of reaction type and mode of occurrence. • Radioactive contaminants • Trace metals • Nutrients • Other inorganic species: Salts and natural metals like Al • Organic contaminants • Biological contaminants

  19. Classes of Environmental Contaminants • Radioactive contaminants • Produced by the nuclear industry • Includes radionuclides 239Pu, 233U, 235U, 238U, 230Th, 226Ra, 222Rn (gas), 90Sr, 137Cs. • Health hazards include ionizing radiation and metal toxicity • Trace metals • Several major sources • Includes Al, As, Ba, Be, B, Cd, Cr, Co, Cu, Pb, Li, Mn, Hg, Mo, Ni, Se, Ag, Sr, Th, Sn, Ti, U, V, and Zn • Health hazards due to toxicity. May bioaccumulate.

  20. Classes of Environmental Contaminants • Nutrients • Several major sources including agriculture and sewage • Includes inorganic and organic sources of nitrogen, phosphorus, and other elements that are nutrients • Health hazards of nitrogen include methemoglobinemia and carcinogenicity of organo-nitrogen compounds. Phosphorus has lower health hazards due to low solubility of inorganic P compounds. Nutrients are important in disrupting ecosystem processes.

  21. Classes of Environmental Contaminants • Other inorganic species • These species are found in nontrace quantities and are major contributors to water salinity. Major ion salinity originates from saline brine contamination, agricultural and mining leachate, and industrial processes. • Includes the cations Ca2+, Mg2+, and Na+, and the anions Cl-, F, HS-, SO42-, HCO3-, CO3-, and H2CO3. • Health hazards of these species are not as serious. Contamination by saline waters can make fresh water supplies unfit for use.

  22. Classes of Environmental Contaminants • Organic contaminants • Major sources include the industrial, agricultural, and energy industries • Includes over 70,000 organic chemicals in use by human society. The EPA priority pollutant list has 116 different organic compounds. • Health hazards of these compounds are varied. They can be carcinogens or have toxic effects on organisms. Because of the large number of compounds, there is incomplete toxicological data on this group of contaminants. There is even less known about the long term ecological damage cause by the persistence of these chemicals in the environment.

  23. Classes of Environmental Contaminants • Biological contaminants • Major sources include animal waste from agricultural practices, sewage from centralized treatment facilities or septic tank systems, and sanitary landfills. • Includes pathogenic bacteria, viruses, or parasites. • Health hazards of these contaminants include disease and abdominal disorders.

  24. 25 Most Common Contaminants Detected in Groundwater at Hazardous Waste SitesDomenico & Schwartz, 1990

  25. Influence of Environmental Characteristics Al, Fe Ca, SO4, Si, CO3

  26. Building Geochemical Conceptual Models: Soil

  27. Building Geochemical Conceptual Models: Estuary

  28. Processes that Affect the Fate and Transport of Contaminants

  29. Geochemical Processes Affecting the Fate and Transport of Contaminants Much of the information required to understand the effects of contaminants released into the environment is centered on understanding and modeling the fate and transport of contaminants. Quantifying the fate and transport is required to perform a risk assessment or predict remediation effectiveness. • Transport/Mixing Processes • Aqueous phase transport: the pollutant is dissolved in water • Nonaqueous phase transport: liquid organic pollutants that form their own phase • Gaseous phase transport: important for volatile inorganics (ex. methylated arsenic) and organics (ex. petroleum)

  30. Geochemical Processes Affecting the Fate and Transport of Contaminants • Geochemical Processes • Hydrolysis and complexation reactions: reactions of the pollutant in solution • Precipitation/dissolution: reaction that transfers pollutant between the solid and liquid phase • Oxidation/reduction reactions: reaction where elements change oxidation state through electron transfer • Sorption and partitioning reactions: pollutant binding to a solid surface or moving into a 3-D material • Biochemical Processes • Microbial degradation of organics: enzyme catalyzed reactions • Microbial methylation of metals: enzyme catalyzed reactions which add a methyl group to a metal

  31. Contaminant Bioavailability and Ecotoxicology Environmental geochemistry is heavily involved in predicting the toxicity of contaminants in different environments. The toxicity of a contaminant is related to the contaminant's bioavailability. Bioavailability is dependent on the relative amounts of each chemical form of the contaminant. Chemical speciation, based on thermodynamics, is used to describe the activity (concentration) of the contaminant in its different forms in any phase.

  32. Contaminant Bioavailability and Ecotoxicology • Basic Premise of Ecotoxicology: The uncomplexed or free metal/organic is typically the most toxic form. • Bioavailability: the degree to which a contaminant is free for uptake by an organism and then affects that organism. • Chemical speciation: a quantitative description of the activities (concentrations) of different forms or species of a compound. Example: species of copper in an aqueous solution: • Cu2+(aq), CuCl+(aq), CuSO4˚(aq), CuOH+(aq),

  33. Contaminant Bioavailability and Ecotoxicology • Conceptual model linking geochemical processes to the bioavailability and toxicity of metal and organic pollutants.

  34. Conceptual Models of Perturbed Geologic Environments

  35. Element or Molecule (Contaminant) Geochemical Processes Affecting the Fate and Transport of Contaminants Molecular Scale Qualitative description of molecular-scale contaminant chemistry : physiochemical properties, specific reactivities Quantification of environmental factors : T, P, pH, Eh, Ionic strength, major ions, organic matter, colloids, microbial populations, NAPL and solid phases Local Macroscopic Systems Quantitative description of individual : environmental processes phase change, complexation, sorption, biodegradation, precipitation-dissolution, redox processes, microbial reactions Quantitative description of Quantitative description of ecosystem components, transport processes and structure and functioning geologic system structure Description of interactions and impacts of human activities , structures and/or policies Environmental Systems Quantitative description of dynamic behavior of chemical in the environmental system : modeling and field investigations

  36. Geochemical Processes Affecting theFate and Transport of Contaminants • Coupled solute transport, geochemical reactions, and biotic degradation in subsurface systems.

  37. NABIR Conceptualization of Biodegradation

  38. Geochemical Processes Affecting the Fate and Transport of Contaminants

  39. Risk Assessment and Risk Management

  40. So how bad is it?

  41. EPA National Water Quality Index: Rivers EPA Index of Watershed Indicators • 16%, better water quality • 36%, some problems • 21% , serious problems The Index characterizes the condition and vulnerability of aquatic systems in each of the 2,111 watersheds in the continental U.S.

  42. EPA National Water Quality Index: Rivers • 19% of all rivers were surveyed • Data reports percentage of impacted watersheds • Agricultural runoff was the dominant source of stressors

  43. Sediment Contamination in the US U.S. EPA Assessment of Sediment Contamination • 20,000 sites but covers • only 11% of the rivers, • lakes and coastline • High concern = watersheds • with >20 Tier 1 sites (known • adverse effects) and 75% • of all sites are Tier 1 & 2 EPA characterized sediment chemistry, sediment toxicity, and fish tissue residue data from individual monitoring stations throughout the nation

  44. The Estuarine Pollution Susceptibility Index NOAA’s National Estuarine Inventory • Built on a watershed- • based spatial framework • Assessments exist for • over 130 estuaries Susceptibility to pollution is defined by the dissolved concentration potential (DCP), the particle retention efficiency (PRE), and by the estimated loadings and predicted concentrations of nitrogen (N) and phosphorus (P).

  45. Sediment Delivery to Rivers and Streams from Cropland and Pastureland Hydrologic Unit Modeling of the US (HUMUS) project • Erosion based on SWAT • estimates • Uses several national- • level natural resource • and land use databases SWAT is a process model incorporating hydrology, weather, sedimentation, crop growth, and agricultural management.

  46. Potential Pesticide Runoff from Farm Fields Hydrologic Unit Modeling of the US (HUMUS) project • Loss based on process • model estimates • Total loss of pesticides • was estimated by summing • loss for all pesticides used This indicator was developed to show which watersheds have the greatest potential for the movement of agricultural pesticides from farm fields through surface water runoff.

  47. Society Interaction with the Natural Flow of Matter and Energy in Geologic Systems Florida Everglades Development has led to excessive nutrient and pesticide loading and disruption of natural hydrologic cycle through channelization in the 1960’s