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Problems with dumping of red mud in shallow waters. A critical review of selected literature
Aquaculture,
267
2 (1973) 267-280
0 Elsevier Scientik Publishing Company, Amsterdam - Printed in The Netherlands
PROBLEMS A CRITICAL
WITH DUMPING REVIEW
OF RED MUD IN SHALLOW
OF SELECTED
WATERS.
LITERATURE
VOLKERT DETHLEFSEN Institut fiir Kiisten- und Binnenfischerei der Bundesforschungsanstalt fiir Fischerei, Laboratorium 219 Cuxhaven, Kapitiin-Alexander-Strafie. (F.R. Germany)
Hamburg.
HARALD ROSENTHAL Biologische Germany)
Anstalt
Helgoland,
Zentrale
Hamburg-Altona,
2 Hamburg
SO, Palmaille 9. (F.R.
(Received March 29, 1973)
Red mud is an industrial waste originating from the production of aluminium from bauxite. Since the difficulties connected with the removal of red mud are increasing and the possibilities for land deposition are restricted, German aluminium-producers wanted to dump their wastes in the southern North Sea. Several experiments were carried out to assess the effects on marine organisms. Red mud proved to be harmful to a variety of organisms; the most predominant effect was agglutination of gill tissues. Regarding the very severe effects of suspended red mud on different marine organisms the authors refuse the proposed dumping project. Taking into account the special hydrographic situation of the German Bight, which cannot be compared with that of other dumping areas and further knowing that the North Sea is one of the most important fishery areas of the world, it is concluded that dumping of red mud would endanger the stocks of bottom fish and fauna and should therefore take place in regions without any fishing activities with depth greater than 3000 m.
INTRODUCTION
Red mud is an unpleasant industrial residue resulting from the production of aluminium. The composition of red mud, the intensive red colour is caused mainly by its contents in iron oxides varies considerably depending on the origin of the bauxites and on different dressing processes. (Table 1). 0.5 to 1.0 tons of red mud are produced with every ton of Al* 03. In
268 TABLE 1 Examples for the composition Compound
of different
red muds Percentages: Baudart (1966)
&O,
Al,O, (water soluble) SO,
Hegenbarth (1973)
Rosenthal (1971)
a
b
5.75 38.75 20.3 _ 13.0
20.0 30.0 13.0
48.0 20.0
9.0
9.0
6.0
(bound)
20.7 31.9 0.5 16.6 10.3
Na,O
5.0
(water soluble)
0.9
CaO TiO
5.0 5.5 0.2
Mr$xides “,Os Ash content (weight loss) Cr,O, Carbonates P,O,
2.0 7.0
3.0 5.0
0.1
0.2
14.0 0.2 -
10.0
0.7 7.4
_
11.0
_ 3.0 _
0.1
0.3 0.2
1970, 870 000 tons of red mud were produced in the Federal Republic of Germany; most of it was deposited on land reservoirs. In consequence of the further development of production capacities of various factories probably more than 3 million tons will have to be disposed of in 1980. In 1973 a new aluminium plant will start manufacturing Australian bauxites near Stade (Elbe). 800 000 tons of red mud (wet weight) will be produced yearly. At present, it seems to be impossible to buy suitable ground for land-deposition in the neighbourhood of the plant. Aluswisse, another aluminium producer plans to build up an oxide plant near Wilhelmshaven in 1976. It is intended to wash the red mud produced at the beginning of the manufacturing process on factory-owned ground on which additional buildings will find a place. Due to the hig costs of transport the possibilities for land deposition are restricted to locations situated near to the oxide plants.
269 Since other countries (France, Great Britain, Jamaica, Japan, Italy, and U.S.A.) are dumping red mud into the sea, the southern North Sea has been considered a suitable dumping area, especially because the plants are or will be situated near the coast. But the North Sea is one of the most important fishery areas of the world and the waste-water load, not only in coastal areas, is already very high, so the question of dumping red mud must be examined very thoroughly. EXPERIENCES THE SEA
OF THE COUNTRIES
WHICH DUMP RED MUD INTO
France Already in 1965, public protests induced French experts from the Institut des PCches to give their decision to a red mud dumping project in the bay of Cassis (Mediterranean). These experts stated authoritatively that red mud should be discharged through a pipeline of 7 km length at a
q q
dead zone. normal
very
bottom
high fauna.
density lower
of
red
density
mod of
red
mud
Fig. 1. Dumping of red mud in the bay of Cassis by a pipeline of 7 km length into a canyon depth, which is declining to 2000 m. The spreading of red mud is restricted (After Bourcier,
350 m 1969).
270
depth of 350 m into a zone declining by 35-40s down to 2000 m. (Fig. 1). The capacity of this canyon is 33,6 milliard m3, enough not to be filled up in four centuries (Baudart, 1966, Gaugenheim et al., 1965, Bourcier, 1968). This dumping procedure by pipeline ensures that red mud does not remount to the surface. Intensive investigations in the dumping area have shown that a dead zone has been established in the centre of the inlet and only organisms able to offer resistance live near the border of the red mud field. (Fig. 1). Great Britain
Since 1939 an aluminium industry has been in existance at the mouth of the river Severn into the Bristol Channel. The red mud produced here was partly mi%ed with sand and then pumped into basins surrounded by dams. This method was practicable up to 1966. After that, the thickened mud was resuspended by water and a ship transported it into the estuary with a tidal range of 12 m maximum. The red mud stain, clearly visible at the beginning of the dumping, is immediately mixed up with sea water and rapidly transported seaward by tidal currents. But the red mud was still pumped into the reservoirs before dumping and in the basin it certainly underwent an additional cleansing step, in the course of which the alkali was neutralized. The resuspension with water when sucked into the dumping vessel certainly changes the adhesive nature of red mud. Altogether, in a period of 6 years until the plant was closed, a total of about 263 000 tons of red mud (dry weight) were introduced into the estuary. Acute injuries have not been established (Davis, 1972). Germany
Following the French experiences in the bay of Cassis, the German aluminium producers were recommended to initiate an experimental dumping in the southern North Sea in order to prove whether red mud can be deposited punctiform in rather shallow waters (40 m) with tidal currents. The Bundesforschungsanstalt fur Fischerei, Hamburg, in cooperation with the Deutsches Hydrographisches Institut, Hamburg, selected an area at 55’ 5’N, 05” 30’E where in a period of 20 days altogether 15 000 tons of red mud were unloaded, in portions of 1000 tons per shipload. During these dumping experiments, different investigations were made on the behaviour of red mud and on the effects on fish and bottom fauna.
271 CHEMICAL
AND PHYSICAL
INVESTIGATIONS
ON RED MUD
With the exception of Hydroxylsodalith red mud contains only minerals naturally occurring in the environment. These minerals are not soluble under normal conditions. Chemical analyses showed that the contents of chromium, lead and sodium were different from those normally found in sediments. The pH of the liquid in which the red mud is suspended is 12.8. During the process of dumping, an increase in the pH of the sea water of pH 0.2 was registered. The pH of deposited red mud is 8.4; sediments covered by a layer of red mud are not influenced. (Nauke. 1973). Recent experiments on red mud originating from dressing of Australian Weipa bauxites showed that iron and aluminium compositions are dissolved in the liquid in which red mud particles are suspended. When contacting sea water, these compositions precipitate and form yellowish white heavily hydrated flakes (Nauke, 1973). X-ray-fluorescence analyses proved the presence of A13+, Fe2 +, Ca2 +, Cl- and S2 - . The quantitative determination of aluminium showed that the precipitate consisted of 15.6% Al2 03. This means that during the dumping of the liquid of 1 kg red mud an aluminium composition containing 0.51 g aluminium flakes out. It is not quite clear if the adhesive nature of red mud particles is due to those precipitates which occur during neutralisation by sea water. French scientists calculated that together with 800 000 tons of dry red mud particles 2.4 million m3 of alkaline water would be introduced, which would cause the precipitation of 25000 tons of magnesium. Sea water contains about 1.4 g Mg/l so that theoretically all magnesium would vanish from a water cube with a length of 270 m. As a result of movements and currents and the buffer capacity of sea water, the disappearance of magnesium is not complete but in the zones where red mud and sea water are mixed during dumping a considerably reduced content of magnesium salts could be registered (Gaugenheim et al. 1965). Due to the cohesion of the very small particles (4-5 1-1diameter) and due to the high density, most of the red mud sinks to the bottom after being dumped, the rest remains susperided for a long time and colours the surface-water layers an intensive red. The experimental dumping in the North Sea showed that red mud extended over the ground unexpectedly fast. (Fig. 2). When dumping was finished, altogether an area of 250 km2 was covered by a thin layer of red mud. Red mud particles could be found 9 knots WNW of the original dumping point. The content of suspended matter, which is normally 0.8- 1.O mg/l, increased to a maximum of 1.7 mg/l.
272 3.5.-
l&5.-18.5.1971
5.5.1971
5000
t.
11000
t.
. . 24.5.-26.5.1971
.
15000
.
l.
I 0 m
closed
red
0
5 - 20
m
less
more
mud
than
fhan
20
t.
1 5
10 sm
layer %
% 5
O/O
Fig. 2 Spreading of red mud in the sauthem North Sea in the couise of an experimental dumping of 15000 tons in the area 55’ lO’N, 5’ 30’E. The circles indicate the positions of van Veen-grabs. (After Nauke, 1973).
JNVESTIGATIONS ORGANISMS
ON THE EFFECTS OF RED MUD ON MARINE
(a) Bottom Fauna The bottom meiofauna in the dumping area was investigated by Apelt (197 1). The main representatives of the area under survey were Nematoda. The number of individuals varies considerably from station to station and even from sample to sample. These, variations are caused by fluctuations in the population density depending on the locality and on the season. Apelt sums up, that the red mud dumped during this test did not kill the bottom meiofauna. At the end of the test the indivudual numbers from the centre and the neighbouring regions of the dumping area were the same or even higher than at the beginning of the investigation. Apelt does not consider one can conclude that the meiofauna is not influenced when covered by a layer of red mud. A prerequisite for a detailed assessment of harmful effects would be accurate data on the status quo in the 3 years (to eliminate seasonal fluctuations) prior to the beginning of dumping.
273
Rachor (197 l), who investigated the bottom-macrofauna without being able to state any harmful effects is of the same opinion. The contents of the intestines of some nematodes and mussels were of red colour due to red mud (Apelt, 1971). Rachor (1971) found red mud built within the tubes of annelids. (b) Experiments
with Net Cages.
Dethlefsen (I.C.E.S., 1972) carried out experiments with net cages. (2 X 2 X 2 m; Fig. 3) in which cod (Gadus morrhua were placed. The cages were sunk for 29 hours and for 5 days. During the 29-hour test, 1 ton and during the 5-day test, 3 tons of red mud were dumped at a distance of about 100-400 m from the submerged cages which were kept IO m and 4 m, respectively, over the ground, total water depth being 40 m.
aluminium
frame-
bottom
wire-
(4 - 10
m) 100 kg
\
ain anchor
Fig. 3. Net cage used to assess the effects of red mud on cod (Gudus morrhua). The aluminium frame, in which the nets were inserted measured 2 x 2 x 2 m.
274 No cod died in the course of the 29-hour experiment. The 5-day experiment showed cod deaths to be 13.6% (10 m over the ground), and 58.8% (4 m over the ground), respectively. Controlling experiments were accomplished within the same month in an area near Heligoland (54” 8’N, 07” 58’E), where the water was not contaminated by red mud (depth 40 m). No cod died in the course of the 29-hour and the 5-day test. The supporting laboratory investigations showed that the gills of all cod killed during the test were heavily agglutinated by red mud particles. This agglutination could not be washed away, not even by rather rough methods. (c) Laboratory Investigations The adhesive nature of red mud particles was also found by Halsband and Halsband ( 197 1) who kept eel (Anguilla anguilla), plaice (Pleuroonectes platessa) and shrimps (Crangon crangon) in aquaria. The agglutinations proved to be so fixed to the gills of the test organisms that they were not able or only very slowly to free themselves after being transferred to clean water. 100
Fig. 4. Laboratory experiment on the sedimention of red mud in artificially moved sea water. The concentration sinks to 20% from the initial concentration in less than 10 hours. (After Paffenhiifer, 1972).
Most of the representatives of locomotive macrobenthos investigated by Greve and Kinne (1971b) (Aster@ rubens, Echoncardium cordatum, Ophiura texturata, Ophiura albida, Psammechinus miliaris, and Eupagurus bernhardus) freed themselves from adhering red mud after being replaced in uncontaminated water. But the time required for the cleansing procedure differed considerably from species to species. Adhesive effects have also been reported by Rosenthal (1971), who used the development of embryos and larvae of herring (&pea harengus)
275 as criteria to judge damaging effects of red mud. The percentage of survival of artificially fertilized and incubated eggs was reduced to about 40-50% (controls 90%), when these eggs were exposed to various concentrations of suspended red mud (1, 2, 5, and 10 ml/l). The red mud particles adhered to the surface of the egg membrane forming an almost regular layer. This behaviour of red mud particles certainly interferes with the gaseous exchange between egg and the surrounding medium; it causes inssufficient oxygen supply to the embryos when development is proceeding and this is the reason for the high mortalities. The investigation further showed that the complete agglutination of the egg surface is almost independent of the initial concentration of red mud particles; lower concentrations merely require a longer period of contact to produce the same effects. In some cases the mouth of newly hatched herring larvae was blocked by red mud particles (Fig.5): it is not known if the larvae are able
Fig. 5. Larva of herring (Ckqea kengus) which has been reared artificially and confronted mud. Red mud particlei stopped up the mouth opening and the oesophagus of the larva. Rosenthal, 1971).
to red (After
to get rid of it prior to the end of the yolk sac stages when feeding normally starts. Paffenhijfer (197 1 and 1972) found delayed growth, increased mortality and lower dry-weight when he investigated juvenile stages of the planctonic copepod, Calanus helgolandicus. Another important finding was that the copepods obviously fed on red mud particles. This finding, together with that of Apelt (197 l), indicates that filter feeding organisms, which are not able to select their food particles, are forced to ingest red
276 mud; therefore the intestine is filled with indigestible material and the normal demand for nourishment cannot be satisfied. The results of Winter’s (197 1) experiments on the influence of turbidity-creating substances on the filter-feeding behaviour of Mvtilus edulis confirm the findings mentioned above. Other experiments on the effects of red mud were carried out by Kayser ( 197 l), Halsband and Halsband ( 197 1) aFd Dethlefsen (1972b) on different planktonic algae, and by Greve (1972), and Grave and Kinne ( 197 1a) on Pleurobrachia pileus and Beroe gracilis. The impairment of the test organisms found in these investigations are, in the opinion of the authors, caused mainly by the physical and mechanical properties of red mud. The institutes involved in the investigations, therefore, decided authoritatively that no dumping of red mud into the North Sea should take place. CONCLUSIONS The dumping of red mud is not the only example for the disposal of waste sludges into the sea. Pearce (1970) and Anonymus (1972) provide information on disposal of large quantities of sewage sludges into the New York Bight for more than a century. The authors of the investigation conclude, after having investigated the benthic communities, crustaceans, bacteria, and zooplankton, that the disposal of sewage sludges had a significant and often deleterious effect on the living resources of the New York Bight. In their preliminary report on the effects of sludge disposal at sea (Firth of Clyde) Mackay and Topping (1970) found some indication of quantitative changes in the fauna. The discharged sludge becomes distributed over a wide area and little obvious harm to the environment has resulted. But the authors point out that these results are rather preliminary. Shelton (1970) investigated a disposal area at the mouth of the Thames where five million tons of sludge are dumped annually. Howell and Shelton (1970) found that the deposition of china clay in St. Austell and Mevagissey Bays has a marked effect on the bottom fauna. These workers cite an unpublished work of Miss N. Sproston (1945) who examined the effects of suspended clay upon species of pelagic fish. No recognizable effect of mica particles, which are present in china clay, upon the gills of fish taken from polluted water could be demonstrated. Portmann (1970) who carried out a sedimentological study in St. Austell and Mevagissey bays, reports that the majority of the china clay waste discharged has been deposited on the sea bed of the bay and has stayed in a small area. This lack of transportation is due to the very weak currents in this area. Mackay et al. (1972) illuminated another problem
277 -connected with the dumping of sludges, that is the increasing heavy metal contamination of sediments and animals. But domestic sewages as well as china clay wastes are not comparable with red mud because of the almost complete absence of adhesive properties. Particles of the oozy bottom of the Wattensea have a similar size to those of red mud but agglutination of the gills of organisms living in this bottom has never been observed. Red mud concentrations used in the laboratory experiments were always higher than those found during experimental dumping. (1) As can be seen from Fig. 2 there has been a continuous red mud layer in the centre of dumping during the experimental dumping; benthic organisms were confronted with really high concentrations which were almost reaching 100%. (2) Most of the authors cited gave the initial concentrations of red mud, which existed at the beginning of the tests. Fig. 4 shows that red mud is depositing in artificially moved sea water so after only a few hours the actual concentrations are about 70-80% lower than those used initially. In addition to that one should regard the different possible compositions of red mud and differing procedures of storing of red mud. These differences certainly result in different properties of the wastes so that the influence on organisms cannot always be the same. The red mud led into the Bristol Chaneel cannot be compared with the material coming from German aluminium production, because it had been treated with sand and water before being disposed of. Besides that, the quantities dumped into the Bristol Channel in 6 years’ were the same which would have been dumped by the State plant annually, without increasing production capacities. ‘In France it was accepted that a dead zone would be established in the prospective dumping area, because almost no fishing takes place there. Due to the special topographic situation this zone would be very small and restricted. The almost total absence of bottom currents ensures that the red mud would not spread from the initial dumping point. In the shallow North Sea, which is one of the most productive fishery areas of the world, only a punctiform deposition of red mud would have been acceptable in order to keep the interferences with fisheries as small as possible. As the red mud proved to spread unexpectedly fast, some consideration was given to the proposal to use this behavior by diluting the red mud in the propeller stream of the dumping vessel and to change the
disposal area from dumping to dumping. The procedure of dilution of wastes in the propeller water of ships is carried out succesfully with wastes of TiOz production near the Island of Heligoland (Weichart, 1970). In the case of red mud a joint authoritative statement from Bundesforschungsanstalt fir Fischerei, Institut ftir Meeresforschung, Bremerhaven, and Biologische Anstalt Helgoland, makes evident that this special dumping procedure would endanger the most important commercially used flat fish stocks such as sole (Solea solea) turbot (Psetta maxima), plaice (Pleuronectes platessa), lemon sole (Microstomus kitt), dab (Limanda limanda). These flat fishes which live on or in the bottom is a rule do not flee at once if they are endangered, as do pelagic fish like herring (&pea harengus), sprat (Spmttus sprattus), cod (Gadus morrhueu), haddock (Mekznogrammus aeglef‘inus) etc. Flat fishes would try to hide in the bottom, so they would not be able to flee the damaging effects of red mud, which sinks down to the bottom at 40 m depth in less than 1 minute. This finding wa obtained by echo-sounding experiments during dumping. Even if fishes were able to escape from the dumping area this must be regarded as harmful to the stocks because of the undesirable reduction of their environment by the steadily spreading red mud. But the removal of red mud seems to be possible without dumping it in the North Sea. There are different examples which show that red mud can be used by other industries. Red mud with higher contents of iron (more than 39%) was used for production of steel soon after the second world war (Hegenbarth, 1972). But the iron content of red mud from Australian Weipa bauxites is too low to allow profitable manufacturing procedures, Small quantities of red mud are added to tiles for roofing. At present it is investigated whether red mud can be used as material for root building, for sanitary landfill, and for melioration of coastal areas. But these procedures cannot remove all the red mud produced in the Federal Republic of Germany in the future. From the standpoint of fisheries there are no objections to dumping the red mud dutside the fishery areas, outside the North Sea at depths greater than 3000 m. The red mud could be loaded into ships, which transported bauxites from Australia to Europe; these ships could unload the red mud over the Atlantic Ocean wlien they return to Australia. ZUSAMMENFASSUNG Rotschlamm ist ein industrielles Abfallprodukt, das bei der Produktion von Aluminium aus Bauxit entsteht. Wegen zunehmender Schwierigkeiten bei der Beseitigung van Rotschlamm und der begrenzten Miiglichkeit einer Deponie an Land beabsichtig-
‘79 ten deutsche Al-Hersteller, diese Abfallprodukte in der siidlichen Nordsee zu versenken. In einem Verklappungsexperiment, bei dem innerhalb von 20 Tagen 15 000 to Rotschlamm versenkt wurden, wurden Schidigungen von Fischen und eine besonders rasche Verbreitung des Rotschlamms festgestellt, von dem man zundchst erwartet hatte, daB er sich punktf6rmig an der Versenkungsstelle anhgufen wiirde. Da such eine Reihe von Laboratoriumsuntersuchungen z.T. schwerwiegende Beeintrgch tigungen der Versuchsorganismen erbrach ten, lehnten die mit diesem Projekt befassten Institute das Verklappungsvorhaben in einer gemeinsamen gutachterlichen Stellungnahme ab. Die besondere hydrographische Situation der Nordsee (flach mit starken Strijmungen) sowie die Tatsache, daB die Nordsee eines der wichtigsten Fischereigebiete der Welt ist, lassen es angeraten erscheinen, derartige Verklappungsprojekte ausserhalb dieses Gebietes etwas aber 3000m Wassertiefe durchzufiihren. REFERENCES Anonymus (1972) The Effects of Waste Disposal in the New York Bight. Summary, Final Report. L!S. Department of Commerce, April, 1972. Apelt, G. (1971) Untersuchungen iiber die Boden-Meiofauna im Rotschlammverklappungsgebiet nordwestiich der Weiaen Bank. 3. Kolloqium zum Schwerpunktprogramm der DFG ‘Litoralforschung Abwasser in Kiistentihe’, Bremerhaven, 10/12/1971. Baudart, G.-A. (1966) Le rejet i la mer. Revue de I’Aluminium. 177- 180. Bourder, M. (1969) Ecoulement des Boues-rouges dans le canyon de la cassidaigne (Ddcembre, 1968). Thetys, 1, 779-182. Davis, V.E. (1972) Erfahrungen bei der Versenkung von Rotschlamm im Meer. [Manuscript presented at the Hauptversammlung der Gesellschaft Deutscher Metallhiitterund Bergleute e.V. in Stuttgart 1972. To be published in 1973.1 Dethlefsen, V. (1972) uber den EinfluR von Rotschlamm auf die Besiedlungsdichte von Griinalgen. Arch. Fischerriwiss., 23, 68-72. Dethlefsen, V. (1972) On the effects of red mud on marine organisms. C.M. (Council Meeting) I.C.E.S. (International Council for the Exploration of the Sea) Fish. Improvements Cttee., E 7 [mimeo] p. l- 7. Gaugenheim, A., Chedin, J., Drach, P., Lacombe, H., Larras, J., Vincotte, J. (Eds.) (1965). Rapport de la Commission d’6xperts charg6s d’examiner les problbmes PO&S par le project de d&versement du boues rouges dam le baie de Cassis. Ministire des Traveaux Publics et des Transports. Minis&e de l’lndustiie. I- 17. Greve, W. (1972) Okologische Untersuchungen an Pleurobrachia pileus. 2. Laboratoriumsuntersuchungen. Helgolinder Wiss. Meeresunters 23, 141- 164. Greve, W. und Kinne, 0. (1971) Untersuchungen zum Einflui3 von industriellen Abw&ern auf Makrozooplankton der Deutschen Bucht. 3. Kolloquium zum Schwetpunktprogramm der DFG 'LitQOrQifOrSChUng Abwasser in Kiistentihe’, Bremerhaven 10/12/1971. Greve, W. und Kinne, 0. (1971). Uber die Reaktion einiger Vertreter des vagilen Makrobenthos auf die Konfrontation mit Rotschlamm. 3. Kolloquium zum Schwerpunktprogramm der DFG ‘Litoralforschung Abwasser in Klstenntihe’, Bremerhaven, 10/12/1911. Halsband, E. und Halsband, I. (1971) Physiologische Studien zur Ermittlung des Schldlichkeitsgrades von ‘Rotschlamm’ in Seewasser. Wasser. Luft, Betrieb, 15, 268-273.
280 Hegenbarth, R. (1972) Bemiihungen des Martinswerkes ZUI Verwertung von Rotschlamm (Ferrosilt*). [ Manuscript to be published in 19731. Howeu, B.R. and Shelton, R.G.J. (1970) The effect of china clay on the bottom fauna of St. Austell and Mevagissey Bays. J. Mar. Biol. Ass. UK., 50, 593-607. Kayser, H. (1971) Abwasserteste an Kulturen mariner Planktonalgen. 3. Kolloquium zum Schwerpunktprogramm
der DFG
‘Litoralforschung
Abwasser
in Kiistennahe’,
Bremerhaven,
10/12/1972. Mackay, D.,W. and Topping G. (1970) Preliminary report on the effects of sludge disposal at sea. Effluent Water Treat. J. 7 pp. Mackay, D.W., Hclcrow, W. and Thornton, I. (1972) Sludge dumping in the Firth of Clyde. Mar. Poll. Bull., 3 (1) 7-10. Nauke, H. (1973) Rotschlammverklappungen in der Nordsee - geologische Ergebnisse eines GroRversuchs. Dt. Hydrogr. Z., im Druck. Paffenhofer, G.A. (1971) EinfluR von Rotschlamm auf Mortalitat und Korpergewicht von Jungstadien des marinen planktischen Copepoden Calanus helgolandicus. Naturwiss., 58, p. 625. Paffenhofer, G.-A. (1972) The effects of suspended ‘red mud’ on mortality, body weight, and growth of the marine planktonic copepod, Calanus helgolandicus, Water, Air and Soil Poll., 1, 314-321. Pearce, J.B. (1970) The effects of solid waste disposal on benthic communities in the New York Bight. FA.0. Techn. Conf marine Poll, Rome, FIR:MP/70/E - 99, 1-12. Portmann, J.E. (1970) The effect of china clay on the sediments of St. Austell and Mevagissey Bays; J. Mar. Biol. Ass. UK., 50, 577-591. Pulley, T.E. (1950) Effect of aluminium chloride in small concentrations on various marine organisms. Texas. J. Sci., 2, 405-411 Rachor; E. (1971) Der Bestand der Makro-Bodenfauna in einem durch Rotschlammverklappungen beeinfluRten Gebiet in der Deutschen Bucht. 3. Kolloquium zum Schwerpunktprogramm der DFG ‘LitoralforschungAbwasser in Kiistenniihe’, Bremerhaven, 10/12/1971. Rosenthal, H. (1971) Wirkungen von ‘Rotschlamm’ auf Embryonen und Larven des Herings; Clupea harengus. HelgoLinder wiss. Meeresunters., 22, 366- 376. Shelton, R.G. (1970) The effects of the dumping of sewage sludge on the fauna of the outer Thames Estuary. C.M. E.8, International Council for the Exploration of the Sea (LCES.). 9 PP. Weichart, G. (1970) Chemical and Physical investigations in the German Bight on marine pollution caused by wastes of a TiO,-Factory. F.A.O. Conf marine Poll., FIR:MP/70/E - 44, l-2. Winter, J. (1970) Long-term Laboratory Experiments on the Influence of Ferric Hydroxide Flakes on the Filter-feeding Behaviour, Growth, Iron Content and Mortality on Mytilus edulis L. FAO Conf marine Poll., FIR:MP/70/E - 112, l-11.
267
2 (1973) 267-280
0 Elsevier Scientik Publishing Company, Amsterdam - Printed in The Netherlands
PROBLEMS A CRITICAL
WITH DUMPING REVIEW
OF RED MUD IN SHALLOW
OF SELECTED
WATERS.
LITERATURE
VOLKERT DETHLEFSEN Institut fiir Kiisten- und Binnenfischerei der Bundesforschungsanstalt fiir Fischerei, Laboratorium 219 Cuxhaven, Kapitiin-Alexander-Strafie. (F.R. Germany)
Hamburg.
HARALD ROSENTHAL Biologische Germany)
Anstalt
Helgoland,
Zentrale
Hamburg-Altona,
2 Hamburg
SO, Palmaille 9. (F.R.
(Received March 29, 1973)
Red mud is an industrial waste originating from the production of aluminium from bauxite. Since the difficulties connected with the removal of red mud are increasing and the possibilities for land deposition are restricted, German aluminium-producers wanted to dump their wastes in the southern North Sea. Several experiments were carried out to assess the effects on marine organisms. Red mud proved to be harmful to a variety of organisms; the most predominant effect was agglutination of gill tissues. Regarding the very severe effects of suspended red mud on different marine organisms the authors refuse the proposed dumping project. Taking into account the special hydrographic situation of the German Bight, which cannot be compared with that of other dumping areas and further knowing that the North Sea is one of the most important fishery areas of the world, it is concluded that dumping of red mud would endanger the stocks of bottom fish and fauna and should therefore take place in regions without any fishing activities with depth greater than 3000 m.
INTRODUCTION
Red mud is an unpleasant industrial residue resulting from the production of aluminium. The composition of red mud, the intensive red colour is caused mainly by its contents in iron oxides varies considerably depending on the origin of the bauxites and on different dressing processes. (Table 1). 0.5 to 1.0 tons of red mud are produced with every ton of Al* 03. In
268 TABLE 1 Examples for the composition Compound
of different
red muds Percentages: Baudart (1966)
&O,
Al,O, (water soluble) SO,
Hegenbarth (1973)
Rosenthal (1971)
a
b
5.75 38.75 20.3 _ 13.0
20.0 30.0 13.0
48.0 20.0
9.0
9.0
6.0
(bound)
20.7 31.9 0.5 16.6 10.3
Na,O
5.0
(water soluble)
0.9
CaO TiO
5.0 5.5 0.2
Mr$xides “,Os Ash content (weight loss) Cr,O, Carbonates P,O,
2.0 7.0
3.0 5.0
0.1
0.2
14.0 0.2 -
10.0
0.7 7.4
_
11.0
_ 3.0 _
0.1
0.3 0.2
1970, 870 000 tons of red mud were produced in the Federal Republic of Germany; most of it was deposited on land reservoirs. In consequence of the further development of production capacities of various factories probably more than 3 million tons will have to be disposed of in 1980. In 1973 a new aluminium plant will start manufacturing Australian bauxites near Stade (Elbe). 800 000 tons of red mud (wet weight) will be produced yearly. At present, it seems to be impossible to buy suitable ground for land-deposition in the neighbourhood of the plant. Aluswisse, another aluminium producer plans to build up an oxide plant near Wilhelmshaven in 1976. It is intended to wash the red mud produced at the beginning of the manufacturing process on factory-owned ground on which additional buildings will find a place. Due to the hig costs of transport the possibilities for land deposition are restricted to locations situated near to the oxide plants.
269 Since other countries (France, Great Britain, Jamaica, Japan, Italy, and U.S.A.) are dumping red mud into the sea, the southern North Sea has been considered a suitable dumping area, especially because the plants are or will be situated near the coast. But the North Sea is one of the most important fishery areas of the world and the waste-water load, not only in coastal areas, is already very high, so the question of dumping red mud must be examined very thoroughly. EXPERIENCES THE SEA
OF THE COUNTRIES
WHICH DUMP RED MUD INTO
France Already in 1965, public protests induced French experts from the Institut des PCches to give their decision to a red mud dumping project in the bay of Cassis (Mediterranean). These experts stated authoritatively that red mud should be discharged through a pipeline of 7 km length at a
q q
dead zone. normal
very
bottom
high fauna.
density lower
of
red
density
mod of
red
mud
Fig. 1. Dumping of red mud in the bay of Cassis by a pipeline of 7 km length into a canyon depth, which is declining to 2000 m. The spreading of red mud is restricted (After Bourcier,
350 m 1969).
270
depth of 350 m into a zone declining by 35-40s down to 2000 m. (Fig. 1). The capacity of this canyon is 33,6 milliard m3, enough not to be filled up in four centuries (Baudart, 1966, Gaugenheim et al., 1965, Bourcier, 1968). This dumping procedure by pipeline ensures that red mud does not remount to the surface. Intensive investigations in the dumping area have shown that a dead zone has been established in the centre of the inlet and only organisms able to offer resistance live near the border of the red mud field. (Fig. 1). Great Britain
Since 1939 an aluminium industry has been in existance at the mouth of the river Severn into the Bristol Channel. The red mud produced here was partly mi%ed with sand and then pumped into basins surrounded by dams. This method was practicable up to 1966. After that, the thickened mud was resuspended by water and a ship transported it into the estuary with a tidal range of 12 m maximum. The red mud stain, clearly visible at the beginning of the dumping, is immediately mixed up with sea water and rapidly transported seaward by tidal currents. But the red mud was still pumped into the reservoirs before dumping and in the basin it certainly underwent an additional cleansing step, in the course of which the alkali was neutralized. The resuspension with water when sucked into the dumping vessel certainly changes the adhesive nature of red mud. Altogether, in a period of 6 years until the plant was closed, a total of about 263 000 tons of red mud (dry weight) were introduced into the estuary. Acute injuries have not been established (Davis, 1972). Germany
Following the French experiences in the bay of Cassis, the German aluminium producers were recommended to initiate an experimental dumping in the southern North Sea in order to prove whether red mud can be deposited punctiform in rather shallow waters (40 m) with tidal currents. The Bundesforschungsanstalt fur Fischerei, Hamburg, in cooperation with the Deutsches Hydrographisches Institut, Hamburg, selected an area at 55’ 5’N, 05” 30’E where in a period of 20 days altogether 15 000 tons of red mud were unloaded, in portions of 1000 tons per shipload. During these dumping experiments, different investigations were made on the behaviour of red mud and on the effects on fish and bottom fauna.
271 CHEMICAL
AND PHYSICAL
INVESTIGATIONS
ON RED MUD
With the exception of Hydroxylsodalith red mud contains only minerals naturally occurring in the environment. These minerals are not soluble under normal conditions. Chemical analyses showed that the contents of chromium, lead and sodium were different from those normally found in sediments. The pH of the liquid in which the red mud is suspended is 12.8. During the process of dumping, an increase in the pH of the sea water of pH 0.2 was registered. The pH of deposited red mud is 8.4; sediments covered by a layer of red mud are not influenced. (Nauke. 1973). Recent experiments on red mud originating from dressing of Australian Weipa bauxites showed that iron and aluminium compositions are dissolved in the liquid in which red mud particles are suspended. When contacting sea water, these compositions precipitate and form yellowish white heavily hydrated flakes (Nauke, 1973). X-ray-fluorescence analyses proved the presence of A13+, Fe2 +, Ca2 +, Cl- and S2 - . The quantitative determination of aluminium showed that the precipitate consisted of 15.6% Al2 03. This means that during the dumping of the liquid of 1 kg red mud an aluminium composition containing 0.51 g aluminium flakes out. It is not quite clear if the adhesive nature of red mud particles is due to those precipitates which occur during neutralisation by sea water. French scientists calculated that together with 800 000 tons of dry red mud particles 2.4 million m3 of alkaline water would be introduced, which would cause the precipitation of 25000 tons of magnesium. Sea water contains about 1.4 g Mg/l so that theoretically all magnesium would vanish from a water cube with a length of 270 m. As a result of movements and currents and the buffer capacity of sea water, the disappearance of magnesium is not complete but in the zones where red mud and sea water are mixed during dumping a considerably reduced content of magnesium salts could be registered (Gaugenheim et al. 1965). Due to the cohesion of the very small particles (4-5 1-1diameter) and due to the high density, most of the red mud sinks to the bottom after being dumped, the rest remains susperided for a long time and colours the surface-water layers an intensive red. The experimental dumping in the North Sea showed that red mud extended over the ground unexpectedly fast. (Fig. 2). When dumping was finished, altogether an area of 250 km2 was covered by a thin layer of red mud. Red mud particles could be found 9 knots WNW of the original dumping point. The content of suspended matter, which is normally 0.8- 1.O mg/l, increased to a maximum of 1.7 mg/l.
272 3.5.-
l&5.-18.5.1971
5.5.1971
5000
t.
11000
t.
. . 24.5.-26.5.1971
.
15000
.
l.
I 0 m
closed
red
0
5 - 20
m
less
more
mud
than
fhan
20
t.
1 5
10 sm
layer %
% 5
O/O
Fig. 2 Spreading of red mud in the sauthem North Sea in the couise of an experimental dumping of 15000 tons in the area 55’ lO’N, 5’ 30’E. The circles indicate the positions of van Veen-grabs. (After Nauke, 1973).
JNVESTIGATIONS ORGANISMS
ON THE EFFECTS OF RED MUD ON MARINE
(a) Bottom Fauna The bottom meiofauna in the dumping area was investigated by Apelt (197 1). The main representatives of the area under survey were Nematoda. The number of individuals varies considerably from station to station and even from sample to sample. These, variations are caused by fluctuations in the population density depending on the locality and on the season. Apelt sums up, that the red mud dumped during this test did not kill the bottom meiofauna. At the end of the test the indivudual numbers from the centre and the neighbouring regions of the dumping area were the same or even higher than at the beginning of the investigation. Apelt does not consider one can conclude that the meiofauna is not influenced when covered by a layer of red mud. A prerequisite for a detailed assessment of harmful effects would be accurate data on the status quo in the 3 years (to eliminate seasonal fluctuations) prior to the beginning of dumping.
273
Rachor (197 l), who investigated the bottom-macrofauna without being able to state any harmful effects is of the same opinion. The contents of the intestines of some nematodes and mussels were of red colour due to red mud (Apelt, 1971). Rachor (1971) found red mud built within the tubes of annelids. (b) Experiments
with Net Cages.
Dethlefsen (I.C.E.S., 1972) carried out experiments with net cages. (2 X 2 X 2 m; Fig. 3) in which cod (Gadus morrhua were placed. The cages were sunk for 29 hours and for 5 days. During the 29-hour test, 1 ton and during the 5-day test, 3 tons of red mud were dumped at a distance of about 100-400 m from the submerged cages which were kept IO m and 4 m, respectively, over the ground, total water depth being 40 m.
aluminium
frame-
bottom
wire-
(4 - 10
m) 100 kg
\
ain anchor
Fig. 3. Net cage used to assess the effects of red mud on cod (Gudus morrhua). The aluminium frame, in which the nets were inserted measured 2 x 2 x 2 m.
274 No cod died in the course of the 29-hour experiment. The 5-day experiment showed cod deaths to be 13.6% (10 m over the ground), and 58.8% (4 m over the ground), respectively. Controlling experiments were accomplished within the same month in an area near Heligoland (54” 8’N, 07” 58’E), where the water was not contaminated by red mud (depth 40 m). No cod died in the course of the 29-hour and the 5-day test. The supporting laboratory investigations showed that the gills of all cod killed during the test were heavily agglutinated by red mud particles. This agglutination could not be washed away, not even by rather rough methods. (c) Laboratory Investigations The adhesive nature of red mud particles was also found by Halsband and Halsband ( 197 1) who kept eel (Anguilla anguilla), plaice (Pleuroonectes platessa) and shrimps (Crangon crangon) in aquaria. The agglutinations proved to be so fixed to the gills of the test organisms that they were not able or only very slowly to free themselves after being transferred to clean water. 100
Fig. 4. Laboratory experiment on the sedimention of red mud in artificially moved sea water. The concentration sinks to 20% from the initial concentration in less than 10 hours. (After Paffenhiifer, 1972).
Most of the representatives of locomotive macrobenthos investigated by Greve and Kinne (1971b) (Aster@ rubens, Echoncardium cordatum, Ophiura texturata, Ophiura albida, Psammechinus miliaris, and Eupagurus bernhardus) freed themselves from adhering red mud after being replaced in uncontaminated water. But the time required for the cleansing procedure differed considerably from species to species. Adhesive effects have also been reported by Rosenthal (1971), who used the development of embryos and larvae of herring (&pea harengus)
275 as criteria to judge damaging effects of red mud. The percentage of survival of artificially fertilized and incubated eggs was reduced to about 40-50% (controls 90%), when these eggs were exposed to various concentrations of suspended red mud (1, 2, 5, and 10 ml/l). The red mud particles adhered to the surface of the egg membrane forming an almost regular layer. This behaviour of red mud particles certainly interferes with the gaseous exchange between egg and the surrounding medium; it causes inssufficient oxygen supply to the embryos when development is proceeding and this is the reason for the high mortalities. The investigation further showed that the complete agglutination of the egg surface is almost independent of the initial concentration of red mud particles; lower concentrations merely require a longer period of contact to produce the same effects. In some cases the mouth of newly hatched herring larvae was blocked by red mud particles (Fig.5): it is not known if the larvae are able
Fig. 5. Larva of herring (Ckqea kengus) which has been reared artificially and confronted mud. Red mud particlei stopped up the mouth opening and the oesophagus of the larva. Rosenthal, 1971).
to red (After
to get rid of it prior to the end of the yolk sac stages when feeding normally starts. Paffenhijfer (197 1 and 1972) found delayed growth, increased mortality and lower dry-weight when he investigated juvenile stages of the planctonic copepod, Calanus helgolandicus. Another important finding was that the copepods obviously fed on red mud particles. This finding, together with that of Apelt (197 l), indicates that filter feeding organisms, which are not able to select their food particles, are forced to ingest red
276 mud; therefore the intestine is filled with indigestible material and the normal demand for nourishment cannot be satisfied. The results of Winter’s (197 1) experiments on the influence of turbidity-creating substances on the filter-feeding behaviour of Mvtilus edulis confirm the findings mentioned above. Other experiments on the effects of red mud were carried out by Kayser ( 197 l), Halsband and Halsband ( 197 1) aFd Dethlefsen (1972b) on different planktonic algae, and by Greve (1972), and Grave and Kinne ( 197 1a) on Pleurobrachia pileus and Beroe gracilis. The impairment of the test organisms found in these investigations are, in the opinion of the authors, caused mainly by the physical and mechanical properties of red mud. The institutes involved in the investigations, therefore, decided authoritatively that no dumping of red mud into the North Sea should take place. CONCLUSIONS The dumping of red mud is not the only example for the disposal of waste sludges into the sea. Pearce (1970) and Anonymus (1972) provide information on disposal of large quantities of sewage sludges into the New York Bight for more than a century. The authors of the investigation conclude, after having investigated the benthic communities, crustaceans, bacteria, and zooplankton, that the disposal of sewage sludges had a significant and often deleterious effect on the living resources of the New York Bight. In their preliminary report on the effects of sludge disposal at sea (Firth of Clyde) Mackay and Topping (1970) found some indication of quantitative changes in the fauna. The discharged sludge becomes distributed over a wide area and little obvious harm to the environment has resulted. But the authors point out that these results are rather preliminary. Shelton (1970) investigated a disposal area at the mouth of the Thames where five million tons of sludge are dumped annually. Howell and Shelton (1970) found that the deposition of china clay in St. Austell and Mevagissey Bays has a marked effect on the bottom fauna. These workers cite an unpublished work of Miss N. Sproston (1945) who examined the effects of suspended clay upon species of pelagic fish. No recognizable effect of mica particles, which are present in china clay, upon the gills of fish taken from polluted water could be demonstrated. Portmann (1970) who carried out a sedimentological study in St. Austell and Mevagissey bays, reports that the majority of the china clay waste discharged has been deposited on the sea bed of the bay and has stayed in a small area. This lack of transportation is due to the very weak currents in this area. Mackay et al. (1972) illuminated another problem
277 -connected with the dumping of sludges, that is the increasing heavy metal contamination of sediments and animals. But domestic sewages as well as china clay wastes are not comparable with red mud because of the almost complete absence of adhesive properties. Particles of the oozy bottom of the Wattensea have a similar size to those of red mud but agglutination of the gills of organisms living in this bottom has never been observed. Red mud concentrations used in the laboratory experiments were always higher than those found during experimental dumping. (1) As can be seen from Fig. 2 there has been a continuous red mud layer in the centre of dumping during the experimental dumping; benthic organisms were confronted with really high concentrations which were almost reaching 100%. (2) Most of the authors cited gave the initial concentrations of red mud, which existed at the beginning of the tests. Fig. 4 shows that red mud is depositing in artificially moved sea water so after only a few hours the actual concentrations are about 70-80% lower than those used initially. In addition to that one should regard the different possible compositions of red mud and differing procedures of storing of red mud. These differences certainly result in different properties of the wastes so that the influence on organisms cannot always be the same. The red mud led into the Bristol Chaneel cannot be compared with the material coming from German aluminium production, because it had been treated with sand and water before being disposed of. Besides that, the quantities dumped into the Bristol Channel in 6 years’ were the same which would have been dumped by the State plant annually, without increasing production capacities. ‘In France it was accepted that a dead zone would be established in the prospective dumping area, because almost no fishing takes place there. Due to the special topographic situation this zone would be very small and restricted. The almost total absence of bottom currents ensures that the red mud would not spread from the initial dumping point. In the shallow North Sea, which is one of the most productive fishery areas of the world, only a punctiform deposition of red mud would have been acceptable in order to keep the interferences with fisheries as small as possible. As the red mud proved to spread unexpectedly fast, some consideration was given to the proposal to use this behavior by diluting the red mud in the propeller stream of the dumping vessel and to change the
disposal area from dumping to dumping. The procedure of dilution of wastes in the propeller water of ships is carried out succesfully with wastes of TiOz production near the Island of Heligoland (Weichart, 1970). In the case of red mud a joint authoritative statement from Bundesforschungsanstalt fir Fischerei, Institut ftir Meeresforschung, Bremerhaven, and Biologische Anstalt Helgoland, makes evident that this special dumping procedure would endanger the most important commercially used flat fish stocks such as sole (Solea solea) turbot (Psetta maxima), plaice (Pleuronectes platessa), lemon sole (Microstomus kitt), dab (Limanda limanda). These flat fishes which live on or in the bottom is a rule do not flee at once if they are endangered, as do pelagic fish like herring (&pea harengus), sprat (Spmttus sprattus), cod (Gadus morrhueu), haddock (Mekznogrammus aeglef‘inus) etc. Flat fishes would try to hide in the bottom, so they would not be able to flee the damaging effects of red mud, which sinks down to the bottom at 40 m depth in less than 1 minute. This finding wa obtained by echo-sounding experiments during dumping. Even if fishes were able to escape from the dumping area this must be regarded as harmful to the stocks because of the undesirable reduction of their environment by the steadily spreading red mud. But the removal of red mud seems to be possible without dumping it in the North Sea. There are different examples which show that red mud can be used by other industries. Red mud with higher contents of iron (more than 39%) was used for production of steel soon after the second world war (Hegenbarth, 1972). But the iron content of red mud from Australian Weipa bauxites is too low to allow profitable manufacturing procedures, Small quantities of red mud are added to tiles for roofing. At present it is investigated whether red mud can be used as material for root building, for sanitary landfill, and for melioration of coastal areas. But these procedures cannot remove all the red mud produced in the Federal Republic of Germany in the future. From the standpoint of fisheries there are no objections to dumping the red mud dutside the fishery areas, outside the North Sea at depths greater than 3000 m. The red mud could be loaded into ships, which transported bauxites from Australia to Europe; these ships could unload the red mud over the Atlantic Ocean wlien they return to Australia. ZUSAMMENFASSUNG Rotschlamm ist ein industrielles Abfallprodukt, das bei der Produktion von Aluminium aus Bauxit entsteht. Wegen zunehmender Schwierigkeiten bei der Beseitigung van Rotschlamm und der begrenzten Miiglichkeit einer Deponie an Land beabsichtig-
‘79 ten deutsche Al-Hersteller, diese Abfallprodukte in der siidlichen Nordsee zu versenken. In einem Verklappungsexperiment, bei dem innerhalb von 20 Tagen 15 000 to Rotschlamm versenkt wurden, wurden Schidigungen von Fischen und eine besonders rasche Verbreitung des Rotschlamms festgestellt, von dem man zundchst erwartet hatte, daB er sich punktf6rmig an der Versenkungsstelle anhgufen wiirde. Da such eine Reihe von Laboratoriumsuntersuchungen z.T. schwerwiegende Beeintrgch tigungen der Versuchsorganismen erbrach ten, lehnten die mit diesem Projekt befassten Institute das Verklappungsvorhaben in einer gemeinsamen gutachterlichen Stellungnahme ab. Die besondere hydrographische Situation der Nordsee (flach mit starken Strijmungen) sowie die Tatsache, daB die Nordsee eines der wichtigsten Fischereigebiete der Welt ist, lassen es angeraten erscheinen, derartige Verklappungsprojekte ausserhalb dieses Gebietes etwas aber 3000m Wassertiefe durchzufiihren. REFERENCES Anonymus (1972) The Effects of Waste Disposal in the New York Bight. Summary, Final Report. L!S. Department of Commerce, April, 1972. Apelt, G. (1971) Untersuchungen iiber die Boden-Meiofauna im Rotschlammverklappungsgebiet nordwestiich der Weiaen Bank. 3. Kolloqium zum Schwerpunktprogramm der DFG ‘Litoralforschung Abwasser in Kiistentihe’, Bremerhaven, 10/12/1971. Baudart, G.-A. (1966) Le rejet i la mer. Revue de I’Aluminium. 177- 180. Bourder, M. (1969) Ecoulement des Boues-rouges dans le canyon de la cassidaigne (Ddcembre, 1968). Thetys, 1, 779-182. Davis, V.E. (1972) Erfahrungen bei der Versenkung von Rotschlamm im Meer. [Manuscript presented at the Hauptversammlung der Gesellschaft Deutscher Metallhiitterund Bergleute e.V. in Stuttgart 1972. To be published in 1973.1 Dethlefsen, V. (1972) uber den EinfluR von Rotschlamm auf die Besiedlungsdichte von Griinalgen. Arch. Fischerriwiss., 23, 68-72. Dethlefsen, V. (1972) On the effects of red mud on marine organisms. C.M. (Council Meeting) I.C.E.S. (International Council for the Exploration of the Sea) Fish. Improvements Cttee., E 7 [mimeo] p. l- 7. Gaugenheim, A., Chedin, J., Drach, P., Lacombe, H., Larras, J., Vincotte, J. (Eds.) (1965). Rapport de la Commission d’6xperts charg6s d’examiner les problbmes PO&S par le project de d&versement du boues rouges dam le baie de Cassis. Ministire des Traveaux Publics et des Transports. Minis&e de l’lndustiie. I- 17. Greve, W. (1972) Okologische Untersuchungen an Pleurobrachia pileus. 2. Laboratoriumsuntersuchungen. Helgolinder Wiss. Meeresunters 23, 141- 164. Greve, W. und Kinne, 0. (1971) Untersuchungen zum Einflui3 von industriellen Abw&ern auf Makrozooplankton der Deutschen Bucht. 3. Kolloquium zum Schwetpunktprogramm der DFG 'LitQOrQifOrSChUng Abwasser in Kiistentihe’, Bremerhaven 10/12/1971. Greve, W. und Kinne, 0. (1971). Uber die Reaktion einiger Vertreter des vagilen Makrobenthos auf die Konfrontation mit Rotschlamm. 3. Kolloquium zum Schwerpunktprogramm der DFG ‘Litoralforschung Abwasser in Klstenntihe’, Bremerhaven, 10/12/1911. Halsband, E. und Halsband, I. (1971) Physiologische Studien zur Ermittlung des Schldlichkeitsgrades von ‘Rotschlamm’ in Seewasser. Wasser. Luft, Betrieb, 15, 268-273.
280 Hegenbarth, R. (1972) Bemiihungen des Martinswerkes ZUI Verwertung von Rotschlamm (Ferrosilt*). [ Manuscript to be published in 19731. Howeu, B.R. and Shelton, R.G.J. (1970) The effect of china clay on the bottom fauna of St. Austell and Mevagissey Bays. J. Mar. Biol. Ass. UK., 50, 593-607. Kayser, H. (1971) Abwasserteste an Kulturen mariner Planktonalgen. 3. Kolloquium zum Schwerpunktprogramm
der DFG
‘Litoralforschung
Abwasser
in Kiistennahe’,
Bremerhaven,
10/12/1972. Mackay, D.,W. and Topping G. (1970) Preliminary report on the effects of sludge disposal at sea. Effluent Water Treat. J. 7 pp. Mackay, D.W., Hclcrow, W. and Thornton, I. (1972) Sludge dumping in the Firth of Clyde. Mar. Poll. Bull., 3 (1) 7-10. Nauke, H. (1973) Rotschlammverklappungen in der Nordsee - geologische Ergebnisse eines GroRversuchs. Dt. Hydrogr. Z., im Druck. Paffenhofer, G.A. (1971) EinfluR von Rotschlamm auf Mortalitat und Korpergewicht von Jungstadien des marinen planktischen Copepoden Calanus helgolandicus. Naturwiss., 58, p. 625. Paffenhofer, G.-A. (1972) The effects of suspended ‘red mud’ on mortality, body weight, and growth of the marine planktonic copepod, Calanus helgolandicus, Water, Air and Soil Poll., 1, 314-321. Pearce, J.B. (1970) The effects of solid waste disposal on benthic communities in the New York Bight. FA.0. Techn. Conf marine Poll, Rome, FIR:MP/70/E - 99, 1-12. Portmann, J.E. (1970) The effect of china clay on the sediments of St. Austell and Mevagissey Bays; J. Mar. Biol. Ass. UK., 50, 577-591. Pulley, T.E. (1950) Effect of aluminium chloride in small concentrations on various marine organisms. Texas. J. Sci., 2, 405-411 Rachor; E. (1971) Der Bestand der Makro-Bodenfauna in einem durch Rotschlammverklappungen beeinfluRten Gebiet in der Deutschen Bucht. 3. Kolloquium zum Schwerpunktprogramm der DFG ‘LitoralforschungAbwasser in Kiistenniihe’, Bremerhaven, 10/12/1971. Rosenthal, H. (1971) Wirkungen von ‘Rotschlamm’ auf Embryonen und Larven des Herings; Clupea harengus. HelgoLinder wiss. Meeresunters., 22, 366- 376. Shelton, R.G. (1970) The effects of the dumping of sewage sludge on the fauna of the outer Thames Estuary. C.M. E.8, International Council for the Exploration of the Sea (LCES.). 9 PP. Weichart, G. (1970) Chemical and Physical investigations in the German Bight on marine pollution caused by wastes of a TiO,-Factory. F.A.O. Conf marine Poll., FIR:MP/70/E - 44, l-2. Winter, J. (1970) Long-term Laboratory Experiments on the Influence of Ferric Hydroxide Flakes on the Filter-feeding Behaviour, Growth, Iron Content and Mortality on Mytilus edulis L. FAO Conf marine Poll., FIR:MP/70/E - 112, l-11.