In addition to the water quality monitoring programme,
monitoring of sediment toxicity is recommended in the EIA to ensure that the
disposal activities are not causing sediments adjacent to the pits of the mud disposal facility to become toxic to
marine life. This programme will
employ standard techniques for sediment toxicity testing which are detailed in
the following sections of this Manual.
The ecotoxicological testing programme shall feature a suite
of tests that include three phylogenetically distinct species that interact
with bedded sediments in different ways.
Unacceptable impacts will have occurred if the levels of contaminants in
the sediments collected in the area of the active pits are shown to have caused
toxicity to marine fauna. The
findings of the sediment toxicity tests shall be compared to the results of the
sediments chemistry.
The objective of this task is to determine if there are any
changes and/or trends caused by disposal activities in the toxicity of
sediments adjacent to the pits as a result of disposal activities.
In accordance with the prediction of the EIA and the
objectives of the Study, the impact hypothesis for this task shall be as
follows:
There is no increase in
sediment toxicity over time at individual stations or a trend of increasing
toxicity with proximity to the pit.
The null hypothesis which should be statistically tested is
as follows:
H0 Sediment collected at sites adjacent
to the active pits exhibits no
greater toxicity than sediment collected at sites remote from the
facility.
In order to determine whether contaminated sediment placed
in the active pits represents an
ecological risk to biota in areas adjacent to the mud pit, ecotoxicological
evaluations shall be performed on sediment collected from these surrounding
areas.
The toxicological testing programme should feature a suite
of tests that includes three phylogenetically distinct species that interact
with bedded sediments in different ways.
The testing programme shall include whole-sediment, or solid-phase
toxicity tests using the epibenthic amphipod, Ampelisca abdita, the burrowing polychaete, Neanthes arenaceodentata, and free-swimming larvae of bivalves (Mytilus galloprovincialis) or other
equivalent species. The species to
be used, either international or local, for the toxicity testing should be
confirmed with EPD/AFCD before commencement of the testing.
The experimental designs for assessing the impacts of disposal
of contaminated mud in either the East
of Sha Chau facility or the South Brothers facility on the toxicity of
sediments in remote and adjacent areas take into account the following factors:
·
The
null hypotheses being tested;
·
Location
of other potential sources of contaminants in the North Lantau region, eg, Pearl River;
·
Predictions
taken from the EIA on sediment plume locations; and,
·
Expected
statistical treatment of the data.
Sediment samples shall be collected from two treatment
areas. The first treatment is
represented by samples taken from two stations in an area close to the active pits (Near-Field) and the
second treatment is represented by samples collected from stations in a
reference area (Far-Field) (Figure 5.4a and 5.4b). At each of the stations, five replicate
composite grab samples shall be taken and used for the sediment toxicity
tests. The stations shall be
sampled twice per year (wet season and dry season). The sediment sampling shall be carried out when the pits are
active. The precise positions of
the sampling stations should be confirmed in advance of the commencement of
disposal activities and agreed with EPD based on the detailed design of the
disposal facility.
Each of the toxicological tests shall be evaluated for
statistically significant increases in toxicity. Statistically significant toxicity shall be determined by
performing an analysis of variance (ANOVA) test that compares the responses
observed in the test treatments with those of the reference treatments. At the end of the monitoring programme
changes in the toxicity of the sediments over time shall be evaluated through
the use of two-factor ANOVA incorporating both spatial and temporal scales of
variation.
Once the data have been evaluated for significance, it is
important to identify potential causes of toxicity and the biological
significance of the observed effects.
The cause of the observed effects needs to be distinguished between 1)
non-persistent contaminants, 2) persistent contaminants, and 3) physical
factors. It is most important to
determine if the cause of the toxicity is due to persistent contaminants that
are derived from the contaminated sediment placed in the pits (eg metals,
pesticides, PAHs, TBT), to non-persistent contaminants (eg sulfides, ammonia,
salinity) or to physical factors (eg grain size).
If the toxicity is due to persistent contaminants that are
associated with disposal operations, the operations plan for the active pitsmay not be effective enough
at managing the containment of contaminated sediment to acceptable levels and
thus should be modified. If the
observed toxicity is due to non-persistent contaminants, the effects may be due
to the pit but they are transient.
The toxicity of these types of contaminants can be assimilated by the
environment in relatively short time periods, and are thus less harmful. If the effects are related to physical
factors, they are again of less concern and would not likely require changes in
the facility operations
plan.
As non-contaminant factors and physical factors can confound
toxicity test interpretation, the ET shall monitor ammonia, sulfides,
interstitial salinity, and sediment-grain size. Each of these factors has been observed to elicit a Atoxic@
response in test organisms, however, they are not factors related to persistent
contaminants of concern. This
information shall be used to investigate any observed toxicity responses and
determine whether the response is due to persistent contaminants or to more
transient factors.
The amphipod toxicity test with Ampelisca abdita (or a
equivalent species as agreed with EPD/AFCD prior to conduct of the toxicity
test) shall evaluate survival following a 10-day exposure to test
sediment. Procedures shall follow
those outlined in PSEP (1995) ([1]) and CEDD's Environmental
Laboratory Guidance Document (1996) (2). The amphipod benthic test shall be
conducted as a static test and shall be performed with 175 ml of sediment and
800 ml of overlying seawater placed in a 1-L glass jar. At test initiation, each of five
replicate test chambers shall be seeded with 20 amphipods. Test chambers shall be maintained at 20°C and shall be checked daily
throughout the test to establish trends in sediment avoidance. After the 10-day exposure, the benthic
tests shall be terminated by sieving the sediments and enumerating the live and
dead amphipods.
The test on Neanthes arenaceodentata (or
a equivalent species as agreed with EPD/AFCD prior to conduct of the toxicity
test) shall evaluate polychaete survival and growth following a 20-day
exposure to test sediment. Test
methods will follow those outlined in PSEP (1995) (3). The test shall be conducted as a static
test, performed in 175 ml of sediment and 800 ml of overlying seawater in 1-L
glass jars. At test initiation,
each of five replicate test chambers shall be seeded with five
polychaetes. Test chambers shall
be maintained at 20°C and shall be checked daily to record
mortality and sediment avoidance.
To promote growth, worms shall be fed TetraMarin8 every third
day throughout the test. After 20
days, the N. arenaceodentata test
shall be terminated by sieving each test chamber and enumerating both live and
dead organisms. Surviving
polychaetes shall be dried and weighed for each test chamber. Average dry weight shall be compared to
initial biomass to determine mean growth for each test chamber.
The larval-development toxicity test shall be performed with
fertilized bivalve embryos eg Mytilus
galloprovincialis or a equivalent species as agreed with
EPD/AFCD prior to conduct of the toxicity test, and shall evaluate
larval survival and development following a 48 to 96-hour exposure to test
sediments. This procedure shall
follow those outlined in PSEP (1995) ([1]). This test shall be conducted in 20 mg of test sediment with
800 ml of seawater in 1-L glass jars.
At test initiation, test jars shall be seeded with 20 to 40 embryos per
ml. Test chambers shall be
maintained at 16°C. At termination, overlying water shall
be decanted and subsamples drawn from the supernatant. Survival and normal larval development
shall then determined under an inverted compound microscope.
In each of the sediment tests, a
native/seawater control (consisting of sediment from the amphipod or polychaete
collection site or clean seawater for the larval test) shall be tested
concurrently with the test sediments.
The control treatment should be included to determine the health of the
test organisms. Sediments
collected from the reference stations shall also be tested concurrently with
test sediments to provide a basis for statistical comparison. For the larval tests, grain-size
controls shall be tested concurrently with the test sediments to discern any
effects related to sediment grain size.
Additionally, a water-only reference toxicant test using cadmium (from
CdCl2) or copper (from CuNO3) shall be conducted with
each batch of test organisms. This
reference-toxicant test provides a measure of relative sensitivity for each
group of test organisms. All
toxicity tests shall be completed and reported within 2 months from collection
of the samples.
Prior to the commencement of disposal activities, the data
collection parameters and testing protocols described above shall be reviewed
and revised where necessary and agreed with the relevant government departments
(eg EPD/AFCD).
Procedures for sampling shall be as for the sediment
chemistry for Sediment Quality Monitoring as detailed in Section 4.8 of
this Manual. Shipments of the
sediments shall be packaged in ice-boxes in order to maintain the sediments at
a constant temperature of 4oC and dispatched by express courier for
immediate testing.
To ensure the quality and integrity of the ecotoxicological
data and subsequent analyses, a QA/QC control program shall be followed that
meets or exceeds the QA/QC program outlined in Chapter 4 of A Testing of Dredged Material for Marine
Disposal: Environment Laboratory
Guidance Document. The QA/QC
program for the facility ecotoxicological program is described below.
Upon sample receipt, samples shall be held at 4° ± 2° C in the dark until required
for testing. Sediment holding
times for biological testing begin the day of sample collection and shall be
kept at a minimum. The holding
time for sediment intended for biological testing shall be 6 weeks. Chain-of-custody forms shall accompany
each batch of samples to track samples and to provide temperature data before
and after shipping.
Clean seawater for holding test organisms shall be
sand-filtered seawater piped directly into the testing laboratory. Seawater used for test water and
control water should be additionally gravity-feed filtered through a 0.45 -mm filter before use for all
test species. Bioassay seawater
should be continually monitored for water quality and the presence of algal
blooms.
Procedures for calibration and maintenance of water quality
equipment shall follow MSL protocols.
All measuring and testing equipment used on this Project should be
traceable to the data collected and should be calibrated before use.
The pH meters used for obtaining water quality data must be
calibrated daily before use according to MSL-M-045, Calibration and Use of pH
Meters. The calibration shall be
documented on the pH Meter Calibration Record sheet. Maintenance on pH meters shall be performed monthly. Maintenance should include visual
inspection, cleaning probes in 0.1 M HCl, and cleaning any corroded contacts.
Refractometers used for obtaining water quality data shall
be calibrated monthly using IAPO Standard Seawater according to MSL-M-048,
Calibration and Use of Refractometers.
The calibration should be documented on the Refractometer Calibration
Record sheet. Refractometers
should be inspected visually and cleaned monthly.
Digital thermometer calibrations shall be performed monthly
by comparison to a certified mercury thermometer as specified in MSL-M-047,
Calibration and Use of Thermometers.
The calibration shall be documented on a Thermometer Calibration Record. Maintenance should include visual
inspection and cleaning of salt and corrosion from connectors and contacts.
Dissolved oxygen meters should be calibrated daily before
use according to MSL-M-046, Calibration and Use of Dissolved Oxygen
Meters. The calibration should be
documented on the Dissolved Oxygen Meter Calibration Record. Maintenance should be performed once
monthly and should include visual inspection, cleaning the probe, and replacing
of probe membrane.
The Fisher Accumet 1003 pH/selective ion electrode meter
with ammonia electrode should be maintained according to manufacturer’s
instructions. The meter should be
calibrated on each day of use with three concentrations of NH4Cl
standards bracketing the expected test concentrations of ammonia. The ammonia probe should be stored in
0.02 M NH4Cl when not in use.
In addition to QA/QC mentioned above, a series of reviews by
qualified laboratory personnel should be implemented to ensure that the data
generated for this Project meets the data quality objectives. These reviews should include the
following:
·
Data
should be reviewed periodically by laboratory personnel to ensure that sample
testing activities are completely and adequately documented.
·
Sample
holding times, sample integrity, test animal handling and acclimation,
equipment calibration, water quality measurements, reference toxicity results,
observations, and control survival shall be reviewed by qualified laboratory
personnel. The results of QC
measurements shall be compared to pre-established criteria as a measure of data
acceptability.
·
A
final data audit by the Quality Assurance Officer shall be performed prior to
submission of the data and report.
This audit will ensure that the data are accurate, traceable,
defensible, and complete, as compared to the Manual. The audit procedure (MSL-Q-005, Quality Assurance Data
Audits) is a statistical, randomized check which involves comparing selected
reported values to the original data.
This procedure is designed to ensure a 95 percent chance of detecting
whether one percent or more reported values disagree with the original data.
The overall quality assurance objective for this Project is
to implement procedures that will ensure the collection of representative data
that is of acceptable and defensible quality. The data quality objectives for the ecotoxicological tests
shall be devised with reference to the previous data quality objectives
established for the previous monitoring programmes for the East of Sha Chau
CMPs.
A negative control provides a measure of test organism
health. Negative control treatment
shall be running concurrent to each toxicity test as a measure of the test
organism's health. For the
amphipod (eg Ampelisca sp ) and
polychaete (eg Neanthes sp) toxicity
tests, the negative control should consist of clean, native sediment that is to
be collected from the test organism's natural habitat. For the bivalve larval test, the
negative control should consist of clean seawater. Acceptable limits for the negative controls shall be defined
with reference to the limits established for the East of Sha Chau CMP
monitoring programmes. If survival
or normal development do not meet the acceptability criteria, all data should
be evaluated and the test may need to be repeated.
Water quality measurements provide documentation of
environmental conditions within the test chambers during the exposure. Temperature, dissolved oxygen, pH, and
salinity shall be measured daily throughout the test. Conditions that are acceptable to maintain the health of the
test organisms shall be defined with reference to the acceptable conditions
defined for the East Sha Chau CMP monitoring programmes. If test conditions are outside the
acceptability criteria, the data will need to be qualified.
The positive control provides a relative measure of test
organism sensitivity. For each of
the bioassays for the active pits, a separate reference-toxicant test should be
performed with each batch of test organisms. The results of the reference-toxicant tests shall be
compared with control charts generated by the testing laboratory for that
species and toxicant. Those
results within two standard deviations of the cumulative mean are considered to
be similar in sensitivity to previous test populations. For amphipods (eg A. abdita) the reference-toxicant test shall be performed with
cadmium in the form of cadmium chloride; for polychaetes (eg N. arenaceodentata) and bivalve larvae
reference-toxicant tests shall be performed with copper as copper nitrate. If the test results are outside the
control limits, the data will need to be qualified.