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B.4.5. Treatment Toxicity
Even if the treatment system
systems does not employ an active substance, MERC will conduct at least
one set of toxicity tests as part of one trial at each location/salinity (Baltimore and Norfolk. The testing is
designed to meet IMO G9 requirements and uses test methods and species employed by the EPA for
Whole Effluent Toxicity (WET) testing of effluents (EPA 2002 and ASTM 2006).
A fish, an invertebrate and a plant (algae) will be used in all ballast discharge tests. Because the
Chesapeake Bay is a mesohaline aquatic environment with salinities ranging from 5 to 25 psu, estuarine
organisms will be used in these tests. The fish species used in the test will be the sheepshead minnow
(
Cyprinodon variegatus
), invertebrate will be a mysid (
Americamysis bahia
; formerly
Mysidopsis bahia
)
and the algal species will be
Isochrysis galbana
, all listed as estuarine test species in EPA’s Short-term
Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine
Organisms (EPA, 2002).
B.5.
Quality Control Requirements
There is potential for variability in any sample collection, analysis, or measurement activity. Field
variability generally contributes more than laboratory variability. Total study error can result from
between sampling unit variability (influenced by design error, inherent spatial variability) and within-
sampling-unit variability (due to sampling, analytical and data manipulation). MERC has implemented
Quality Management System, documented in the MERC Quality Management Plan, which describes
quality assurance and quality control (QA/QC) measures that are applied to all aspects of MERC BWTS
testing.
Quality assurance measures undertaken to assure the reliability of the data collected include:
•
Duplicate sampling to ensure sample representativeness with respect to sampling and handling
procedures. The acceptable range of relative percent difference between a sample and its duplicate is
20% unless specified otherwise in a specific test plan. Data falling outside this range is invalid.
•
Replicate analysis to ensure sample representativeness with respect to sample processing and
analysis. The acceptable range of relative standard deviation among replicate analyzes is 10%. Data
falling outside this range is invalid.
•
Calibration and maintenance procedures, schedules, and standards (if applicable) for all equipment
used in the test. For example, temperatures of refrigerators and incubators are verified with
independent thermometers on a regular basis. Calibration of pH probes is performed using
appropriate standard solution ranges, etc.
Quality control measures are actions to assure that defined standards are met in the analysis of data. These
measures are analyte or method specific and are defined within the relevant SOP. MERC quality control
measures include:
•
Method blanks to ensure the workspace, handling procedures, and reagents are free from
contamination.
•
Positive and negative controls establish that the method is working as designed.
•
Matrix spikes, to determine percent recoveries of specific analytical methods. Known quantities of
the analyte are added to the sample. After subtracting out the background level naturally present in
the unspiked sample, a percent recovery can be calculated by dividing the measured value by the
known spiked value.