Environmental Chemistry - 552 Chesapeake Bay Study

Example of Environmental Sampling, Analysis, Modeling, and Quality Assurance in Environmental Measurements and Baseline Studies

References:
"An Elemental Ratioing Technique for Assessing Concentration Data From a Complex Water System" Kingston and Greenberg, Environmental International, Vol. 10, pp. 153-161, 1984. (assignment)

Report, The Characterization of the Chesapeake Bay: "A Systematic Analysis of the Toxic Trace Elements," by Kingston et. al., NBSIR 83-2698, NBS, 1983.

Problem:

Decline in water quality in the Chesapeake Bay in general, decline in fish and crab harvests, obvious pollution and environmental degradation.

Goal:

Establish a determination of the state of the Bay and determine a baseline for future comparison.

Resources:

Specific Parameter:

This portion of the study is to establish the elemental content of the water column and the suspended particulate elemental loading in the entire Chesapeake Bay.

Additional Problem that arose during the study.

Question: What is natural and what is anthropogenic and how can we tell the difference? We can only manage anthropogenic inputs.

Chesapeake Bay Study

Study of inorganic baseline levels of trace and toxic elements in the water column, specifically:

Cd, Ce, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sc, Sn, Th, U, Zn

Chesapeake Bay Background

Largest estuary in the United States

One of the worlds most biologically productive estuaries

Population living close to the Bay

Large drainage area covering portions of:

Five state capitols included in the drainage basin

Drainage basin includes:

99% of all waste entering the Bay will not be flushed into the Atlantic Ocean. Thus, all but 1% of the wastes that enter the Bay will stay in the Bay.

Average depth < 7 meters (22 feet)

Waste from Industry, Agriculture, Municipal, Residential, Government

60% of phosphate is from sewage treatment plants (Anthropogenic)

60% of nitrate is from atmospheric deposition & agricultural runoff (Anthropogenic)

Origin of heavy and trace metals unknown.

Planning

Define Problem

- Which elements, analyzed without compromise, sampled at what locations at what depths?

Choose:

Methods of Sampling
(without contaminating)
Methods of Sample Storage
(maintain integrity)
Methods for Instrumental Analysis
Techniques and Personnel to perform
Sampling, Analysis preparation, etc.
Data Analysis
Model Development

Method of Sampling

Judgmental:
One meter under surface and 1 meter above bottom using specially constructed sampling equipment.

Method of Sample Storage/ Technique

Particulate: Filtering in class-100 clean laboratory aboard ship, Filter size fraction 0.45 µ filters of two single lots.

Aqueous fraction: Acidify with sub-boiling double distilled nitric acid.

Storage: In pre acid, leached 1L polyethylene bottles for a single lot of polymer and pre-tested.

Methods of Analysis

Neutron Activation Analysis (NAA)
Graphite Furnace Atomic Absorption Spectrometry (GFAAS)

Method of sample preparation for analysis
All preparations were in Class-100 clean laboratory

Aqueous portion-

Solid Phase Chelation (SPC) separation
SPC then elution in acid matrix (GFAAS)
SPC resin direct analysis by (NAA)

Particulate portion-

0.45 µm filtration, direct analysis of filters
Neutron Activation Analysis (NAA)
Acid decomposition then (GFAAS)

Data Analysis

Elaborate statistical analysis of groups, batches in sampling, preparation and analysis. (Quality Control)

Requirement
55 blanks taken along with 102 bulk aqueous samples and 102 sets of particulate samples.

Blank analysis and sample trend analysis prior to data correction.

Develop Hypothesis about anthropogenic versus natural material present and develop a method for detection of anthropogenic sources.

Test Hypothesis

Develop an Environmental Model for this purpose.

Evaluate data using Model demonstrate conclusions.

Other Analytical Considerations and Tasks:

Design sampling and experiments
Build equipment
Prepare reagents
Install equipment on ship
Sampling time ~ 5 weeks of boat time
Test equipment
Perform sample preparation
Perform instrumental analysis
Perform data analysis
Develop insightful conclusions
Develop hypotheses and test them
Write reports
Present Results
Etc.

Did it accomplish the goals?

What was learned?

What did it cost?

What did this study cost?

Over $700 million has been spent trying to clean up the Bay.

How? The study was feasible and data of quality was obtained.

What was learned?

What the baseline concentrations are in the water column for both particulate and dissolved metals.

Methods of sampling that work.

Methods of chemical processing that work.

Appropriate statistical and mathematical data treatment.

How to do an appropriate baseline study.

That we know how to do the measurements correctly at very low levels if experts in this field of measurements are employed.

How to tell the difference between natural concentration and anthropogenic contributions in particulates in water systems.

Some specific sources of anthropogenic metal contamination in this particular system.

Let's look at the Study, Methods Results, Hypotheses, Model, and Conclusions as an Example

Relating to Chapters 1, 2, 3, 4, 5, Modeling, Sampling, Analysis, etc.

Ref:
"An Elemental Ratioing Technique for Assessing Concentration Data From a Complex Water System" Kingston and Greenberg, Environmental International, Vol. 10, pp. 153-161, 1984.

Notes Table of Contents

Environmental Chemistry Home Page

Duquesne University Home Page

Revised 6/14/98.