Volume 7/Number 1/January 1976

Elbe. No major changes in the benthos were detected and the observed decline of some important elements of zoo- plankton in the North Sea during the sixties seemed unrelated to the rise of the rich year classes in the stocks of plaice and of gadoids. The hypotheses to account for the rise were discussed: first, the possible shift in timing (as part of a climatic change) of the spring plankton outburst towards the spawning season of these fishes so that their larvae exploited the food available to them to a better advantage; second the larval plaice and gadoids may have suffered less predation by adult herring or have gained food that might have earlier been eaten by herring. No evidence was presented to decide between the two hypotheses and indeed it is possible that both postulated events occurred at the same time.

D. CUSHING

Organic Pollutants in the Sea: A Discussion

Despite the great increase in research effort on many aspects of sea pollution in recent years, our knowledge of what happens to organic pollutants in the marine environ- ment, and of the effects they may produce, is still very limited. While this is particularly evident in respect of the vast array of synthetic substances so widely used now in industry, there are still formidable gaps in our under- standing of such common and ubiquitous pollutants as oil and sewage.

Does sewage have an important enriching effect on the sea or is there such an imbalance in the nutrients it contains as to give rise to risks of eutrophication and blooms of unwanted and even toxic algae? Is oil destroyed naturally by microorganisms or do some fractions persist in marine animals? Is the worst behind us in regard to contamination by pesticide residues such as DDT and dieldrin and by other persistant halogenated hydrocarbons used in industry? Are there other unrecognized risks arising from lesser-known chlorinated hydrocarbons or have we pinpointed the potential hazards in time and taken the right steps to avoid trouble in the future? Are there organic substances accumulating in sediments and have we sufficiently sophis- ticated equipment for recognizing their presence and for assessing their significance as hazards to fish, shellfish and other marine life? Are we satisfied that we know where the risks to public health might lie and how to avoid them?

These are some of the questions examined in the papers presented at a Discussion Meeting organized by Dr H. A. Cole and Dr J. E. Smith at the Royal Society in London on 4 - 5 July 1974. The Papers are included in a special volume of the Proceedings of the Royal Society, Series B, Volume 189, Issue No. 1096, 1975.

OECD Mediterranean Environmental Report

Stronger government action over the deterioration of the coastal environment is urged in a pilot study drawn up for OECD's Environment Committee. Though dealing specifically with coastal areas of member countries on the

Mediterranean, the study is relevant to other countries facing similar problems stemming from tourism, energy, transport, urban and industrial development in coastal areas.

The seriousness of the problem is due in particular to the increasing concentration of populations and activities on coastal land. In the countries participating in the study - France, Greece, Italy, Spain and Yugoslavia - the popu- lation in coastal areas is increasing 3 or 4 times faster than the total population.

In addition to a secretariat analysis viewing the Mediterranian problem from various angles, the study contains recommendations by an expert group from the five countries. These chiefly advocate "in depth" planning to relieve the coastline proper and to provide better land use, and the siting whenever possible of the transport infra- structure some distance away from the coastline. The group also warns against increasing the discharge of wastes on land, in the air or inland waters as a result of reducing discharges in the sea, and argues in favour of integrated management of all these factors. Copies of the report, "Mediterranean Pilot Study on Environmental Degradation and Pollution from Coastal Development", are available from: OECD News Division, 2 rue Andr6 Pascal, 75775 Paris Cedex 16, France.

Assessing Potential Ocean Pollutants

Since July 1972, a group of American environmental scientists have been meeting, under the auspices of the U.S. National Academy of Sciences, in an attempt to establish procedures for predicting which materials might jeopardize future ocean resources. Thousands of substances enter the ocean system through industrial, agricultural, and domestic activities, and hundreds of new chemicals are added to the list each year. Very little work has been done to assess the potential effect of these compounds, and the group chose four compounds for a trial investigation: mercury, PCB's, asbestos, and tetracycline. The chemical characteristics of each potential pollutant that would make it a danger to the marine environment were determined, and the production and release to the environment were evaluated. In addition, if the pollutant occurred in nature, the man-induced and natural fluxes in the environment were compared. Trans- port of the material within the environment was assessed by examining data from the atmosphere, rivers, sewer outfalls, marine waters and dredged materials. The concentration and residence times of the material in such environmental reservoirs as the atmosphere, mixed and deep ocean layers, and biosphere were estimated, and the ultimate environ- mental fate of the material studied.

As a result of this initial study it was decided that a task force should assemble data on a wider range of potential ocean pollutants including: hospital wastes, agricultural wastes, litter, synthetic organic chemicals, dumped materials and transuranic elements. The task force started work in June 1973, and for 3 months probed the widely- dispersed information sources for pertinent data. Nearly 1200 pages of background reports were produced. A

workshop was then held with 3 main objectives. (1) To assess and extend our information base and technical ability for handling unanticipated effects of man's products and activities in the marine system. (2) To appraise the method used to accumulate information in the task force and evaluate the background reports. (3) To predict future effects that might arise from the use of the materials considered and to formulate recommendations for action.

Marine Pollution Bulletin

The deliberations of that workshop, together with relevant material from the background papers, have been collected together in a report, which is now available. (US National Academy of Sciences. Assessing potential ocean pollutants, xx, 438p. Washington D.C., Nat. Acad. Sci. U.S., 1975) Orders to: Printing and Publishing Office, Nat. Acad. Sci. U.S., 2101 Constitution Ave., NW, Washington, D.C., 20418, U.S.A.

Environmental Study of the Disposal of Red Mud Waste

Alkaline red mud is a waste product of extracting alumina from bauxite and it is produced in large quantities. This report examines the ecological consequences of red mud waste during the first 18 months of operation of a refinery in the Northern Territory of Australia.

In the process of extracting alumina from bauxite with caustic soda, approximately half of the ore is waste material which is disposed of as an alkaline red mud slurry.

At tile refinery on the Gove Peninsula in the Northern Territory of Australia, this waste is slurried with sea water and pumped into a settling pond (present area is approx- imately 73 ha) at a rate of one million tonnes per annum. Additional sea water is pumped into the pond to neutralize the free alkali, and the supernatant liquor discharged into the sea.

This report describes the chemistry of the wastes, the method of their disposal and the influence on the environs after the first 18 months of operation. Disposal P rocedure

As the bauxite is mined by an open cut strip mining operation to a depth of only 3 - 4 m, it would be impractical to return the red mud to the mined areas because of the difficulties associated with restoring the vegetation cover of the red mud over such a large area. In addition, the effects on the only freshwater supply (via the aquifer) could not be predicted. Also, in view of the long distance from the mine to the plant site (over 20 km) pumping the slurry back would be impractical. Ocean dumping via a pipeline or vessel was not considered, as the nearest point where ocean depths are greater than 200 m is over 500 km from the Grove Peninsula.

The topography is only slightly undulating and so the natural swamp areas were selected for the pond sites.

This method of disposal results in a deposit of red mud solids on land and the discharge of supernatant into the sea, whereas in most other refineries the total red mud waste is either ocean dumped or completely land enclosed with the caustic elements of the supernatant recycled. Monitor ing Programme

Monthly samples of water are taken at nine stations located along the course of the creek which drains the supernatant from the settling pond, and at a further sixteen stations set out in three transects across Drimmie Arm (Stations 1-25 Fig. 1).

4

Samples are also collected at monthly intervals from the pipeheads discharging both red mud and sea water into the pond (PH1 and 2) and from the supernatant outflow points at the sluice gates (DB1 and DB2) which are located at the head and midway along the creek. Samples from stations 1-25 have been analysed for pH, alkalinity (OH-, CO32-) and magnesium ion concentration. The samples collected from pipeheads and sluice gates since the initiation of

Scale 1:56,000

Pipeheads

Red mud pond

Security pond

"- DB r

>1-5

8

Ore conveyor

lg l a 17

DRIMMIE ARM

2S 24 2.3

22 21

Fig. 1 Location of sampling stations.