Mr. DOWNING. Doctor, we thank you, and the committee is pleased to know that there has been advance work done in the environmental field as far as ocean mining is concerned. How long have you all been engaged in this work? Mr. ROELS. We started in the spring of 1970. It is a little over 3 years now, Mr. Chairman. Mr. DOWNING. In the mining, would the effluent, falling back into the ocean, cause any environmental damage? Mr. ROELS. Well, we should distinguish here between the two types of mining systems which are currently being envisioned. One which has been tested, to our knowledge, is an airlift pumping. With airlift pumping, air is injected, as you know, in a pipe which is close to the ocean floor and at intermediate levels. That air travels to the surface very fast and brings with it, at great speed, bottom water nodules and some sediment. The fact that air is being injected is already an environmental advantage, meaning that, when the effluent is discharged at the surface it is very well aerated, indeed. As a matter of fact, it is oversaturated with air and oxygen. The question is then where would this water go? If it would fall immediately back to the sea floor there probably would be no problem. In the tests which we monitored on the Blake Plateau, this discharge water stayed at the surface. This could be an environmental advantage, because this deep water is rich in nutrients such as nitrates, phosphates and silicates so necessary for plant life. Once this is discharged at the surface, the marine food chain could be activated, provided the discharge was great enough. A potential disadvantage might be that, if too great a bloom was stimulated, eutrophication might occur. How ever, we know quite well from monitoring this test that no eutrophication will occur because the concentration of the deep water discharged at the surface was too low. If anything, some advantage will occur to the environment in that productivity will be stimulated. As far as the continuous bucket dredge system goes, we have not been able, in the one test which we have monitored in August and September of 1972 in the Pacific, to find any traces of deep water discharge problems. This is not surprising, since any deep water would be washed out of the buckets as they come up through the |