Ch. 6— Environmental Considerations • 237 



Box 6-F. — Deep Ocean Mining Environmental Study (DOMES) 



The objectives of the first phase of the DOMES program were: 



1. to estabUsh environmental baseUnes at three sites chosen as representative of the range of selected envi- 

 ronmental parameters likely to be encountered during nodule mining, 



2. to begin to develop the capability to predict potential environmental effects of nodule mining, and 



3. to contribute to the information base available to industry and government for development of appro- 

 priate environmental guidelines. 



Field work associated with the studies included upper water layer measurements of currents, light penetra- 

 tion, and plant pigments and the primary productivity, abundance, and species composition of zooplankton 

 and nekton. Temperature, salinity, suspended particulate matter, nutrients, and dissolved oxygen were meas- 

 ured throughout the water column. Current measurements were also made in the benthic boundary layer. 

 Abundance and distribution of benthic populations and characteristics of the sediments and pore water were 

 determined. In addition, the seasonal and spatial variability of chemical and biological parameters at four 

 oceanographic depth zones were studied: 



1. the surface mixed layer, 



2. the pycnocline, 



3. the bottom of the pycnocline to 1,300 feet, and 



4. 1 ,300 to 3,300 feet — were characterized for future comparison with measurements made during actual 

 mining activities. 



The second phase of the DOMES project focused on refining predictive capabilities through analysis of 

 data acquired during pilot-scale tests of mining systems. Two successful pilot-scale mining tests were moni- 

 tored in 1978, one using both hydraulic and air-lift mining systems, and one using air-lift only. Each test 

 saw hundreds of tons of manganese nodules brought from water depths of 13,000 to 16,400 feet to the surface. 

 These tests established the engineering feasibility of deepsea mining, provided the first opportunity to observe 

 actual effects of operations such as those envisioned for the next decade, and allowed comparisons of those 

 effects with earlier estimates of mining perturbations. During these tests, discharge volumes, particulate con- 

 centrations, and temperature were measured from each mining vessel; limited studies were made of the sur- 

 face and benthic plumes; and biological impact assessments were made. The second phase of DOMES con- 

 sisted of monitoring actual pilot-scale mining simulation tests. Its objectives were: 



• to observe actual environmental effects relevant to forecasting impacts, and 



• to refine the database for guideline development. 



SOURCE: U.S. Department of Commerce, NOAA, Office of Ocean Minerals and Energy Deep Seabed Mining, Final Programmatic Environmental Im- 

 pact Statement, Vol. 1, September 1981. 



seafloor directly in the mining path or nearby would 

 be disturbed by the collector and the subsequent 

 sediment plume. In addition, when the nodules 

 reached the mining ships, the remaining residue 

 (consisting of bottom water, sediments, and nod- 

 ule fragments) would be discharged over the side 

 of the ship, resulting in a surface discharge plume 

 that might also cause adverse impact. 



The Final Programmatic Environmental Impact 

 Statement concluded that of 20 to 30 possible neg- 

 ative impacts (see table 6-2) from deepsea mining, 

 only 3 were of sufficient concern to be investigated 

 as part of the 5-year research plan required by the 

 1980 Deep Seabed Hard Mineral Resources Act.*"^ 



"Public Law 96-283. 



The first of the three important impacts occurs 

 at the seabed. First, the collection equipment will 

 probably destroy benthic biota, an impact which — 

 as in the case of shallow water mining — appears 

 to be both adverse and unavoidable. The degree 

 of disturbance depends upon the kinds of equip- 

 ment used and the intensity of mining. The affected 

 biota include animals such as sea stars, britde stars, 

 sea urchins, sea cucumbers, polychaete worms, and 

 sea anemones. NOAA did not identify any ben- 

 thic endangered species in the area that may be af- 

 fected by bottom disturbance. Most benthic ani- 

 mals in the DOMES area appear to be tiny detritus 

 feeders that live in the upper centimeter of sedi- 

 ment and are fed by organic material that falls from 

 upper waters. A worst-case estimate is that the ben- 



