INTERNATIONAL MARITIME ORGANIZATION
E
IMO
SCIENTIFIC GROUP - 26th Meeting
22-25 April 2003
Agenda item 5.1
LC/SG 26/5
11 April 2003
ENGLISH ONLY
MONITORING OF THE MARINE ENVIRONMENT:
REPORTS AND ASSESSMENT OF MONITORING
A Field Survey for the Environmental Impact Assessment of
Disposal at Sea of Bauxite Residue
Submitted by Japan
SUMMARY
Executive summary:
In November 2002, the Japan Aluminium Association conducted a
field survey for the Environmental Impact Assessment of disposal at
sea of bauxite residue. The attached paper reports the results of this
survey. This Environmental Impact Assessment is being conducted in
accordance with the time schedule shown in document LC/SG 25/4/2,
Table 2. Additional information concerning the reusability of bauxite
residue, which builds on the information provided last year in
document LC/SG 25/4/3/Rev.1, is also presented.
Action to be taken:
To take note of and comment as appropriate.
Related documents:
LC/SG 25/4/2; LC/SG 25/4/3/Rev.1.
***
For reasons of economy, this document is printed in a limited number. Delegates are
kindly asked to bring their copies to meetings and not to request additional copies.
I:\LC\SG\26\5.doc
MED/RC/jjf
LC/SG 26/5
ANNEX
A Field Survey for the Environmental Impact Assessment of Disposal at Sea of Bauxite Residue
1.
INTRODUCTION
1.1
Japan presented a field survey plan for the disposal of bauxite residue at sea in the SG25 meeting.
According to this plan, we conducted in November 2002, a preliminary survey of the water quality, bottom
sediment and marine organisms at the disposal site and its surrounding waters. The purpose of this survey
is to determine whether bauxite residue actually exists or not at the bottom of the sea under the disposal
site and to know how the bauxite residue is accumulated. Some of the samples collected from this survey
have already been analyzed. Data on the analyzed samples is shown in this report. On the basis of the
results of this survey, the further work program to be proposed is also introduced in this report. The
program includes acquisition of more detailed basic data on the water quality, bottom sediment and marine
organisms, a bauxite residue distribution survey using a deep-sea camera, a simulation of diffusion and
deposition, and bioassay.
1.2
This paper also presents a progress in the study of utilization of bauxite residue for cement
production with the objective of reducing its quantity to be disposed at sea. Plant trials started last year to
utilize bauxite residue at one of the largest cement manufacturers. Although this is as yet in an
experimental stage, approximately 3,000 dry tonnes of bauxite residue has been shipped for this trial so far.
1.3
Analytical data on chemical contents of bauxite and bauxite residue were reported in the 25th SG
meeting. This paper provides additional data on 15 samples that were taken from 3 alumina plants in Japan.
2.
Preliminary Survey
2.1
Contents of Preliminary Survey
.1
The survey was conducted on November 4 through November 14, 2002 in the “Area B off the coast
of Shikoku” which is a ocean disposal site of bauxite residue. This site is located about 180 nautical miles
of south off Shikoku. The site lies on the “Shikoku Ocean Basin,” which is a flat ocean basin at a depth of
about 4,500 m (Fig. 1). The Area B for ocean disposal has been used as a disposal site of bauxite residue
since 1991. A total of approximately 1,400,000 tons (dry basis) of bauxite residue were disposed until 2001.
1
35°
200
10 00
1000
20 00
3000
34°
SHIKOKU
20 0
1000
1 000
40km
St.N20
200 0
Center Point
(St.C)
3000
33°
Reference
(St.R)
4000
4 00 0
20km
2 00
Nankai Trough
1 000
3 00 0
2 00 0
400 0
32°
St.E20
St.W40
20 0
1000
10 00
4000
40 00
3000
120km
St.W20
10 00
2000
Disposal Site
40 00
200
10 00
1000
30 00
40 00
31°
2 00
4000 3000
20 00
2000
2000
St.S20
Shikoku Basin
4 00 0
30 00
2000
3000
30°
4000
2000
2000
400 0
4 00 0
3000
2000
2000
2000
100 0
4 00 0
2000
2 000
200
1 000
29° 1000
4000
3000
1000
1 00 0
1000
2000
30 00
4000
30 00
2 00
1000
40 00
4 000
129°
130°
131°
132°
4000
3000
3 000
4000
0
100
300km
200
40 00
3 00 0
133°
3000
400 0
30 00
3000
2000
2000
3000
300 0
134°
135°
136°
137°
138°
139°
140°
Fig.1 Map of Disposal Site and Sampling Points
.2
The survey items and sampling procedure are shown in Table 1.
.3
One sampling point was placed in the center of the disposal site (St.C), and four sampling points
were placed 20 km away from the center point to north, south, east and west each (St. N20, St. S20, St. E20
and St. W20). A sampling point, 120km east to the center but with the identical flow regime and bottom
sediment characteristics was established as a reference sampling point (St.R).
One more sampling point
was added at 40km west (W40) to the center to make a total of seven sampling points (Fig. 1).
2
Table 1
Items
WATER QUALITY
SEDIMENT
St. C
○
○
St.
N20
−
○
Survey Items, Sampling Points and Procedure
Sampling Points
St.
St.
St.
S20
E20 W20
−
○
−
○
−
○
St.
W40
−
○
St. R
○
Procedure
Seawater samples were collected from each
sampling layer (0, 100, 200, 500, 1000, 2000 and
Bottom+10 m) with a Rosette water sampling
system (24 two-and-a-half-liter Niskin water
samplers + a CTD) (Photo 2) and analyzed for
bauxite residue index elements, trace elements,
nutrients, etc. Also, the turbidity to a depth of
1,500 m was measured with a recording-type
turbidity
meter
(ATU2000PK:
ALEC
ELECTRONICS CO., LTD.).
○
Bottom sediments were collected with a box-core
sampler (33 cm x 33 cm x 40 cm (the height of
sampled sediment)). The condition of the surface
of sediment at the bottom was photographed on
board a ship. Sub-core samples (a diameter of 94
mm) were also collected and analyzed for bauxite
residue index elements, trace elements, nutrients,
etc.
For bauxite residue index elements, samples were
collected every 1 cm up to a depth of 5 cm below
the surface of the sub-core collected from St. R, St.
C and St. W40.
Phytoplankton
Phytoplankton was collected from each
sampling layer (0, 100 and 200 m: euphotic
zone) with a Rosette water sampling
system.
Zooplankton
Zooplankton was collected with a NORPAC net by
vertical haul from a depth of 200 m to the surface
of the sea.
BIOLOGICAL DATA
Plankton
○
−
−
−
−
−
○
Micro-nekton
○
−
−
−
−
−
○
Meio-benthos
○
○
#
○
#
○
○
Micro-nekton was collected with the Isaacs-Kidd
Midwater Trawl (IKMT) by oblique tows from a
depth of 500 m to the surface of the sea.
Sub samples (a diameter of 34 mm) were collected
from the bottom sediment that was collected with
the box-core sampler. Sediment samples were
collected every 1 cm up to a depth of 5 cm below
the surface of the sub-core
Note#: Sampling of meio-benthos at points St.S20 (20 km to the south) and St.W20 (20 km to the west) was not conducted ,
since the collected sediment lost their shapes.
3
Photo 1
2.2
.1
Photo 2
Photo 3
Results of the Survey
In this survey, a thin layer of reddish brown material, which appears to be bauxite residue, was
visually observed at the sea floor of six sampling points: the center of the disposal site (St. C), four points
20 km to the north, south, east and west from the center (St. N20, St. S20, St. E20, and St. W20), and one
point 40 km to the west from the center (St. W40) (See Photo 4). The reddish brown material was not
observed on the surface at the reference point (St. R) 120 km away to the east from the center.
Photo 4
The surface of bottom sediment
at the center (St. C) of the disposal site
.2
The turbidity was measured every one meter below the surface of the sea up to a depth of 1,500 m
with a turbidity meter at the center point of the disposal site (St. C) and the reference point (St. R). The data
from all layers was below 1 ppm, and the results revealed that there was no turbidity. Also, suspended
solids (SS) was measured for seawater samples collected from the surface layer, depths of 100 m, 200 m,
500 m, 1,000 m and 2,000 m, and approximately 10 m above the sea floor at the same sampling points (St.
C and St. R). The SS data from all layers also had the concentration of below 1 ppm. Since this survey
revealed that the concentration of SS was low at 10 m above the sea floor, the sign of turbidity was not
4
observed near the sea floor. In order to obtain more detailed data, sequential photographing of the condition
of the sea floor with a deep-sea camera and sampling of non-disturbed sediment and water immediately
above the sea floor with a multiple corer will be carried out in the next survey.
.3
Since the disposal site is located at very deep water in the subtrophic ocean far off the coast, the
primary production in the surface layer is said to be low. For this reason, very small amount of biomass is
found at the deep-sea floor. Table 2 shows the composition and amount of meio-benthos collected from the
sediment at the center point (St. C) and the reference point (St. R). No difference was observed between
the sampling points. More detailed data on meio-benthos will be collected in the next survey.
As for phytoplankton (Table 3), zooplankton (Table 4) and micro-nekton (Table 5), no difference of their
composition and amount was observed between the center point of the disposal site (St. C) and the
reference point (St. R).
Table 2
Meio-Benthos Found in the Deep Sea Sediments
(Unit:Inds/10cm2)
Species Name＼Sampling Point
Layer(cm)
1 FORAMINIFERIDA
2 NEMATODA
3 Egg of LORICIFERA
4 MOLLUSCA
5 ARTHROPODA
6 OTHERS
Total
Table 3
0-1
1
24
2
2
6
35
Reference Point
1-2
2-3
3-4
1
+
+
27
14
8
+
3
2
5
4
+
2
4
1
38
23
13
4-5
+
8
1
9
0-1
1
26
4
+
2
4
38
Center Point
1-2
2-3
3-4
+
+
+
21
8
13
4
+
1
1
+
4
1
+
30
11
15
4-5
1
11
+
2
1
16
Phyto-Plankton Found in the Water Column
(Unit : cells/l)
Species Name
1
2
3
4
5
6
7
CYANOPHYCEAE
CRYPTOPHYCEAE
DINOPHYCEAE
CHRYSOPHYCEAE
BACILLARIOPHYCEAE
HAPTOPHYCEAE
PRASINOPHYCEAE
Total
0m
80
56
13
122
3,447
160
3,878
Reference Point
100m
200m
120
29
2
13
132
40
960
320
360
1,614
362
5
0m
20
18
7
351
4,647
80
5,123
Center Point
100m
2
60
30
56
800
948
200m
40
7
32
120
199
Table 4
Zoo-Plankton Found in the Water Column
(Unit:Inds/m3)
1
2
3
4
5
6
7
Species Name
CNIDARIA
ANNELIDA
OSTRACODA
COPEPODA
EUPHAUSIACEA
CHAETOGNATHA
CHORDATA
Total
Reference Point
5.6
4.7
53.3
1.9
8.5
4.6
78.6
Table 5
Center Point
6.6
0.9
8.5
53.3
3.8
6.5
12.2
91.8
Micro-Nekton Found in the Water Column
(Unit:Inds)
1
2
3
4
5
6
Species Name
GONOSTOMATIDAE
MYCTOPHIDAE
PHOSICHTHYIDAE
ANGUILLIFORMES
CONGRIDAE
OTHERS
Total
Reference Point
374
40
26
16
15
25
496
Center Point
534
32
32
11
5
38
652
3.
FUTURE WORK PROGRAMME
3.1
As the results of preliminary survey, the distribution and condition of reddish brown layer that
appears to be bauxite residue was confirmed on the sea floor at a depth of 4,500 m for the first time. At the
same time, basic information on the water quality, bottom sediment, and marine organisms was collected
around the disposal sites. However, to complete the environmental impact assessment, more detailed data
is required.
3.2
The next survey is scheduled in May 2003 to collect detailed data on the disposal site. The purpose
of this survey in May is to conduct the water quality, bottom sediment, and marine organisms surveys and
to get more information on the distribution and condition of reddish brown layer that appears to be bauxite
residue and the condition of turbidity, using an deep-sea camera. The details are shown in Table 6.
6
Table 6
Items
DEEP-SEA CAMERA
WATER QUALITY
SEDIMENT
BIOLOGICAL DATA
Meio-benthos
Micro-nekton
3.3
Survey Items, Purposes and Methods
Purposes
To get more information on the
distribution area of material derived
from bauxite residue at the sea floor
To identify the turbidity between the
surface of the sea and the bottom layer
and bauxite residue index elements
To determine the particle size of bottom
sediment by layer and to identify the
bauxite residue index elements
To identify meio-benthos inhabiting in
bottom sediment and determine the
species and number of individuals
To identify micro-nekton inhabiting near
the disposal site, determine the species
and number of individuals, and examine
whether or not bauxite residue index
elements
are
accumulated
in
micro-nekton
Methods
To observe the floor with an FDC(Finder-installed
Deep-sea Camera)
To sample water with a Rosette water sampling
system
To sample water directly above the sea floor with a
multiple corer
To sample sediment by layer with a multiple corer
To sample sediment by layer with a multiple corer
To sample micro-nekton with the Isaacs-Kidd
Midwater Trawl (IKMT) by oblique tows from a
depth of 500m to the surface of the sea
The preliminary survey revealed that the sea floor around the disposal point was covered with a
thin layer consisting presumably of certain sizes of bauxite residue. However, the particle size of the
bauxite residue is not uniform, ranging from the easily falling larger particles to the fine particles. It is also
assumed that the particles are falling in aggregate form to some extent. Considering the above, a detailed
numerical simulation analysis will be conducted, using data on the current velocity observed near the
disposal site, to determine on which layer and in what concentrations these particles fall and disperse.
3.4
Bauxite residue disposed into the sea is forced to go down as quickly as technically possible, with
subsequent gradual dispersion and settlement. In order to study the effects of bauxite residue dispersion
and sedimentation on various marine organisms, following bioassay will be carried out (Table 7).
- Bioaccumulation of toxic elements from bauxite residue in marine organisms :
Focusing on organisms in both low and high order of the food chain, some experiments will be
performed to consider accumulation of bauxite residue constituents in organisms.
- Study on the effects of turbidity which occurs during falling process of bauxite residue :
Acute toxicity tests will be performed, in order to consider the effect of momentary exposure of
phytoplankton, zooplankton and fish to colloidal suspension and eluate of bauxite residue.
- Study on the effects of bauxite residue sediments on benthic organisms :
Tests involving observation of behavior and determination of acute toxicity will be performed, in
order to consider the effect of bauxite residue deposits on the behavior and mortality of benthic
organisms.
7
Table 7
Items
Accumulation
Effects of
sedimentation
process
Experimental
organisms
polychaetes （ sand
worm
approximately 0.5g
in weight）
Fish
(e.g. red sea bream
or flounder
approximately 10 g
in weight)
Phytoplankton
Zooplankton
Fish
Effects after
sedimentation
Benthic organisms
Bivalves (e.g.
short-necked clam)
(shell length: 1∼
2cm)
Note: [
Proposed Bioassay using Bauxite Residue
Type of Experiment＊
Bioconcentration test
[Diet]
Duration of
experiment
28 days
Endpoint
Accumulation of As, Cr, etc.
Bioconcentration test
[Diet]
56 days
(accumulation
28days, excretion
28days)
Accumulation of As, Cr, etc.
Acute Toxicity Test
[Suspension]
Acute Toxicity Test
[Suspension]
8 days
Acute Toxicity Test
[Suspension]
Acute Toxicity Test
[Cover soil]
Observation of behavior
[Cover soil]
4 days
Confirmation of rate of
reproduction
Mortality / Percentage of
Immobility
Confirmation of condition of
particle attachment
Mortality, Confirmation of
condition of particle attachment
Mortality
Behavior
Behavior (siphon protrusion
percentage), Sand burrowing
percentage
] indicate method of exposure
8
24 hours
10 days
Repetition during
short period
4.
4.1
Utilization of Bauxite Residue to Minimize its Quantity Disposed at Sea
Utilization of Coarse Bauxite Residue for Cement Production
Photo 5
Classification of bauxite residue produces a coarse fraction
which accounts for about 10% of the total residue. Plant trial
to utilize this coarse residue started successfully in 2002 at
one
of
the
largest
cement
manufactures
in
Japan.
Approximately 3,000 dry tonnes of coarse residue has been
shipped so far for cement production. Use of the residue is
planned to be gradually increased in quantity with the cement
quality carefully checked.
Photo 6
Following Japan’s policy to promote a recycle-oriented
society, Japanese cement industry is trying intensively to use
various industrial wastes such as steel slug and coal ash as
substitutes of natural raw materials. Bauxite residue is one of
the candidate materials that could be used for this purpose.
However, to increase its quantity for utilization, there are
several problems to be solved, e.g., how to remove unsuitable
elements such as soda and chlorine contained in the bauxite residue. Attention should also be paid to its
handling to prevent dusting caused by fine fractions of bauxite residue. (Photo5: Shipment of bauxite
residue at alumina plant. Photo6: Charge of bauxite residue into cement process)
4.2
Utilization of Whole Bauxite Residue
As mentioned above, the coarse fraction classified is only 10% of whole bauxite residue. To be able to use
a larger quantity, the remaining fine fraction must be utilized as well. For the purpose of utilizing all of the
bauxite residue regardless of its classification, research and development work has been carried out.
Table 8 shows that fine fraction of bauxite residue contains more Na2O and less Fe2O3 than coarse fraction.
Table 8
Analysis of Coarse and Fine Fraction
Fine Residue
Coarse
Residue
Constituent（％）
24
20
Al2O3
12
14
SiO2
Fe2O3
50
42
Na2O
2
6
particle size（％）
8
1
+1000μm
30
3
1000∼500μm
According to our laboratory tests, the amount of
fine fraction that can be added to cement
production will be limited to 1% of cement
clinker, as compared with a few % for coarse
fraction. Larger scale tests are planned this year
to confirm the maximum possible addition of
bauxite residue, properties of cement produced,
preferable state of bauxite residue to be added
with respect to its handling, etc.
9
5.
Trace Elements in Bauxite Residue
In the last Scientific Group Meeting, results of extraction test of bauxite residue and chemical contents of
bauxite and bauxite residue were presented in Table 2-3 (LC/SG25/4/3/Rev.1) to show that bauxite residue
is uncontaminated.
In the discussion several questions were raised e.g., chemical data based on 3 samples
were too limited to provide a convincing argument about the characteristics of bauxite residue. A mass
balance would be necessary as well.
In reply to these questions, 5 samples were taken from each of the 3
alumina plants in Japan. Accumulated analytical data were given in Table 9.
Table 9 Chemical Composition of Trace Element in Bauxite and Residue
Element
Arsenic
Mercury
Fluorine
Vanadium
Chromium
Copper
Nickel
Cadmium
Lead
Zinc
Bauxite(mg/kg dry)
67
0.08
336
237
141
16
4
<0.5
18
27
Residue(mg/kg dry)
110
0.12
801
658
427
24
11
<0.5
40
43
Ratio
2.3
1.8
2.5
3.1
3.6
2.0
2.8
2.5
2.2
Note: Average of 15 samples taken from 3 alumina plants
1 ton of bauxite that Japanese alumina manufacturers are currently using generates 0.3 – 0.4 ton of bauxite
residue, depending on source of bauxite. It is accordingly assumed that after alumina is extracted in the
process, the various trace elements originally contained in the bauxite becomes concentrated by 2.5 – 3.5
times in the residue.
Table 9 shows residue/bauxite ratio of trace elements.
This demonstrates fairly
good mass balance of inputs and outputs with analytical precision taken into account.
that no trace elements were added or generated in the process.
10
This also confirms