Chlorinated hydrocarbons in sewage

Chlorinated hydrocarbons in sewage

Marine PollutionBulletin Ecological problems with a floating bridge across the Strait of Georgia will have to be examined, such as the effec~ on migra...

131KB Sizes 2 Downloads 48 Views

Marine PollutionBulletin Ecological problems with a floating bridge across the Strait of Georgia will have to be examined, such as the effec~ on migrating salmon species, both in their journey toward the sea as juveniles and in their return to their native streams to spawn as adults,

Controve r y O v e r Tailin s Disnosal

P 1) ~ --]l'OrO----


A proposal to discharge tailings from a molybdenum mine at Kitsault, British Columbia, into Alice Arm at the head of Observatory Inlet on the northern coast of British Columbia has been challenged by the Nishga Native Indians. They claim that the marine food chain will be unfavourably affected, and this in turn will have an adverse effect on fishing carried out traditionally by the Indians in this inlet system. A federal order-in-council was approved in April 1979 setting up special Alice Arm Tailings Deposit Regulations, which would exempt the mine operators from having to abide by existing regulations set up under the Fisheries Act. The existing regulations require that suspended solids in effluent from a mining operation not exceed25 ppm. The mine proposes to discharge tailings (the finely ground rock from molybdenum extraction) through an outfall discharging at 50 m depth in Alice Arm, which has a maximum depth of 380 m. A threshold sill of 30 m depth separates deep water in Alice Arm from that in the main part of Observatory Inlet. Production will be at 12,000 tonnes of ore per day on an ore body that is expected to last 26 years with a total production of 100 million tonnes of tailings. There was an earlier mine operation at the same site, from 1967 tp 1972, with production of molybdenum from 6,000 tonnes of ore dally. The tailings at that time were dumped into Lime Creek, draining into Alice Arm, and ultimately ended up on the bottom of Alice Arm. In the House of Commons on 8 July 1980, when the Honourable Romeo Le Blanc, the Minister of Fisheries and Oceans, was questioned on this matter, he stated the issue will be reviewed. The Nishga tribal council wants all work on the project to stop until a full inquiry can be held.

Chlorinated -" t l-y a-r o c a r D o n s


L.,~wa~, In order to evaluate the effects of municipal waste waters on populations of mussel, crab and holothurians and on the chlorinated hydrocarbon content of sediments, 300 1. per day of settled sewage were added to an experimental basin 65 m s and 0.6 m deep in the lagoon of Strunjan in the Northern Adriatic. A lagoon of similar size was used as a control. The pesticide and PCB content of the fauna and the sediments from the lagoons and from offshore waters within 14 nautical miles of the coast were determined, In the case of mussels and crabs only the edible parts were used for analysis after homogenization. Because this technique is difficult with holothurians, cold acid extraction of the organochlorine compounds was used. Sediments were dried, homogenized" and extracted. All extracts were concentrated to dryness and solvent extracted, treating part of the extract with alkaline ethanol as a preliminary step in 276

the determination of aldrin, DDT and Dieldrin, using chromatographic methods. The results showed that the sediments in the polluted basin contained about three times the concentration of DDT and its derivatives, and PCBs, as the unpolluted basin. This higher concentration was due to the sewage because all the other samples, including those taken in the sea areas, showed much lower values. In these samples from the sea area an increase in chlorinated hydrocarbon content was detected nearer the shore. The influence of sediment composition on the fauna examined was to cause a two or threefold increase in chlorinated hydrocarbon content in the holothurians which are deposit feeders and mussels which are filter feeders but this was not the case with crab, which is a predator and scavenger. The results of sediment analysis showed differences in DDT and PCB concentration which could be explained by the proximity of the sampling areas to sources of pollution, as well as to the size of the sediment particle; since the chlorinated hydrocarbons are held by the surface physical property of adsorption by the particles and the surface of a given weight of sediment increases as the particles become smaller, fine particles were formed to contain a greater proportion of hydrocarbon than the larger grains. These results are reported by I. Salihoglu (Turkey), J Faganeli and J. Stirn (Yugoslavia) in Rev. Int. Oc~anogr. M~d.Vol. 58, 1980.

Salvors ncourageu to Combat OilPollution A new agreement which alters the standard Lloyds rules governing salvage of stricken vessels at sea is seen by the oil tanker industry as a significant step forward in dealing with the threat of pollution. The changes to Lloyds standard salvage agreement, known as Lloyd's Open Form (LOP) have modified the strict 'no cure no pay' stipulations previously in effect which, it was felt, gave insufficient economic incentive to salvors to use their best efforts to avoid pollution in the course of saving a laden tanker in trouble. The outcome of two year's of talks by a Lloyd's working party representing salvors, shipowners, oil companies and underwriters is a new LOF that guarantees payment of salvors costs - a 'no cure, some pay' clause - if government authorities require the vessel to be sunk to prevent pollution. Previously the salvor was rewarded on the basis of the value of the ship, cargo and freight saved, but not for any actions in preventing pollution and potential pollution liability. Four out of every five salvage operations are conducted under LOF and another clause added to the modified agreement covers the 'Flying Dutchman syndrome' where ports refuse entry to a leaking tanker, as illustrated in 1979 when the damaged tanker Andros Patria remained under tow at sea for 50 days unable to find an Atlantic port willing to accept her until all her oil was removed from the vessel. To encourage salvors to assist a vessel potentially likely to be similarly treated the new clause allows salvors to end their services if they and the vessel owners disagree over a safe place to take the vessel.