Workshop 2.0: Trends, Loadings, and Spatial Patterns
LEMN Workshop 2.0: "Trends, Loadings, and Spatial Patterns" was a binational workshop that was held at the Stull Interpretive Center, Presque Isle State Park, Erie, Pennsylvania from September 11th to 12th, 2000.
Workshop Agenda: Download (PDF)
Workshop 2.0 (Trends, Loadings, and Spatial Patterns) was hosted by Mr. Kelly Burch (PADEP) with financial assistance from the Pennsylvania Sea Grant. Twenty-three scientists & managers attended the two-day meeting on September 11-12, 2000. The workshop was characterized by a series of presentations interspersed with break-out sessions and round table discussions. Two additional workshops focusing on Mechanisms & Processes and Ecosystem Implications are planned to follow (TBD).
This workshop was designed to be a review session to ask the following questions:
- What are the major classes of contaminants?
- Where are they located in the lake?
- Where are they located in the food web?
- Is our monitoring good enough to detect problems?
A series of GIS-based presentations that used maps of the location of different chemicals in the Lake Erie basin sediments revealed some very clear groupings of chemicals:
- urban/industrial chemicals (PCBs, PAHs, heavy metals such as mercury and lead). These tended to be located primarily at harbours and downstream of large cities
- rural-related chemicals (nutrients, pesticides). Major areas of contamination are located in and at mouths of rivers
- other chemicals tend to arrive in the lake largely through atmospheric deposition
Based upon the co-occurrence of these suites of chemicals, the workshop participants concluded that we can summarize chemicals into 5 classes:
- PCB, mercury, dieldrin; industrial source; 'legacy' chemicals
- PAHs; industrial & urban sources; active inputs
- Agrochemicals; pesticides/herbicides + nitrates; nutrients
- Dioxin/furans [atmospheric inputs important]
- chemicals of emerging concern; probably urban
The survey and discussion produced consensus on several important issues. Some can be construed as good news; others are cause for concern:
- The new GIS techology lets us make detailed maps of the distribution of chemicals. This permits one to easily see patterns that would be difficult to detect from mathematical or model-based approaches alone. Consequently, the delineation of problem areas and location of the source of problems is getting much easier to identify, even though monitoring resources are limited.
- Because classes of compounds seem to be problems only in particular areas, we don't have to sample everywhere for all of the compounds
- Levels of many 'legacy' compounds (formerly used; now banned) are declining.
- The vast majority of compounds are buried in the sediments. Relatively speaking, there are minuscule quantities in the biota (but see the 'causes for concern' below).
Causes for Concern
- In many areas, the detection limits used by agencies to monitor chemicals (especially legacy chemicals) are higher than levels thought to have probable effects in biota.
- There is no funding available to continue monitoring for any project.
- Agricultural and rural use trends are increasing at an alarmingly rapid rate. Many feel that chemical contaminants stemming from these activities will be the next major threat to the ecosystem.
- Major changes in the behaviour of chemicals in the ecosystem are linked to biological changes in the food web [zebra mussels, Hexagenia mayflies, plankton]. Changes in the distribution and abundance of these organisms cause changes in energy and contaminant transfer patterns. Therefore we must understand the biology of the animals making up the food web to solve our most serious contamination problems.
- We need a full literature review of the contaminant trends among biological compartments of the ecosystem. This work is in progress.
- There is need for a group to oversee and recommend procedures for standardizing the types of data collection and reporting.
- There is need for a standard data repository, like STORET.
- There is need to address and understand the biological processes involving contaminant transfers. This will be the topic of the next LEMP Research Needs workshop in the series.
- We must discuss how to integrate the need for mass balance/budget modelling (which predict how things will change) with the need to understand the transfer processes within the system. This will be a topic of a later LEMP Research Needs workshop in the series.
- We must integrate knowledge and research about in-lake processes with information on inputs from the rivers. As a first step, an integrative workshop will be held at the conclusion of the Detroit River 'State of the Strait', and 'Lake Erie in the Millennium' binational conferences in Windsor, Ontario, 29 March 2001