ESM220 Ecological Risk Assessment

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ESM220 Ecological Risk Assessment

• Feb 5, 2008
• Project Assignment 1 due
• Conceptual Models contd
• Ex risks of elevated CO2 to terrestrial
  ecosystems
• Flow Charting Basics
• Analysis of Exposure - Thursday

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What is a Conceptual Model?

• Portrays the system being assessed
• Diagram of the hypothesized causal relationship
  between the source of an agent and the response
  of the endpoint entities
• Describes the source, the receiving environment
  and the processes by which the receptors come to
  be exposed directly to the agents and indirectly
  to the effects of the agents on other
  environmental components
• Hypothetical, conceptual, descriptive - not
  quantitative

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Uses of conceptual models

• Defining the risk hypothesis main purpose
• Screening rule out implausible hazards from the
  assessment if no source, pathway, receptor or
  mechanism for harm can be developed
• Defining mathematical models
• Causality define mechanisms underlying
  relationships between observed effects and
  hypothesized causes work backward
• Heuristics learning by discovery
• Communication aids understanding by
  stakeholders and RM
• Life cycle definition origin, distribution and
  fate of agent

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Other chars of conceptual models

• Should contain exactly the sources, endpoints and
  pathways included in the assessment
• But sometimes more complex than the implemented
  model
• Conceptual models may be iterative
• Input to problem formulation process
• Screening assessment
• Elimination of unsuitable receptors, routes of
  exposure, potential sources
• during prob formulation process
• after results and new information

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Forms of Conceptual Models

• Diagram with some explanatory text
• Arrows depict the relationships between
  components of the system (sources, agents,
  affected entities)
• May be pictorial with entities as images
• May be map-based to show spatial relevance
• May be alternating states and processes
• Most are flow charts

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Flow Charts

• Tutorials
• Generic info on the www
• Software packages, e.g, Visio by MS
• Free ware, open source
• http//home.att.net/dexter.a.hansen/flowchart/flo
  wchart.htm
• http//www.esd.ornl.gov/programs/ecorisk/documents
  /tm186.pdf

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Creating Conceptual Models

• Techniques
• Build from basic relationships
• Break model into modules
• distinct spatial units, distinct processes,
  distinct entities (Fig 17.5)
• Linking of standard component modules
• Use generic components for sources, endpoint
  entities or processes which are repeated
• Receptor, source site conceptual models Figs
  17.6 .7
• Generic conceptual models
• Brain storming and pruning
• Representing implemented models
• ERA conceptual models should link to other
  conceptual models relevant to the RA same
  sources, routes of transport

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Analysis Plans

• Last step in problem formulation
• Defines data to be collected
• Models/statistical/ logical analyses that will be
  applied
• Type of results to be presented
• Milestones
• Completion date
• Resources and effort required
• QA plan specifies uncertainty
• Reference information - baseline

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• EPA AQUATOX Example
• http//www.epa.gov/waterscience/models/aquatox/tra
  ining/2006-day1notes.pdf

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