of 1 to 30 /ig/1, and its vertical distribution (surface deple- 

 tion, deep enrichment) is very similar to that of a major plant 

 nutrient — silicate (fig. 4). 



Fluxes of elements in association with sinking plankton detri- 

 tus were measured with particle interceptor traps at three depths 

 (range = 50-100 m) in coastal and open-ocean Pacific waters. 

 Observed rates of change for carbon, nitrogen, and phosphorus 

 and inferred rates of oxygen change varied widely in relation to 

 surface productivity. For example, oxygen utilization rates cal- 

 culated from the carbon fjux data were as high as 650 jul/T 1 / 

 year 1 at 100 m under upwelling conditions and as low as 

 18 jal/H/yr 1 at 1,000 m in the open ocean. The investigators 

 also concluded that quantities of passively sinking particulate 

 carbon, nitrogen, and phosphorus appear to be in excess of the 

 amounts required to meet the nutritional needs of the midwater 

 zooplankton, even in the open ocean when fluxes are relatively 

 low. 



Continuous culture experiments showed that natural popula- 

 tions of marine phytoplankton concentrate ionic copper. Con- 

 centration of copper was from two to six times higher in cells 

 from cultures containing 1 to 2 /xg copper per liter. Additional 

 observations were: 



(1) Effects of copper concentration varied between species; 



(2) Cell division was inhibited in one diatom species, Lepto- 

 cylindus danicus; 



(3) Copper was lethal to another diatom, Ceratulina bergonii; 



(4) Intracellular processes of chlorophyll synthesis or carbon 

 production were not inhibited; 



(5) Chlorophyll per cell increased slightly (thought to be 

 owing to reduction in cell division); 



(6) Primary production in the diatom, Skeletonema costatum, 

 did not decrease (only species on which this was tested). 



Cultured phytoplankton take up arsenic (As) in a period of 



2 to 3 days when grown in a media enriched with 5 to 25 ^g 

 As(V) per liter (fig. 5). Both the inorganic and methylated As 

 levels in the cells increased by about 50 percent in Skeletonema 

 costatum. The As content of Peridinium trochoidium increased 

 drastically under the same conditions, with cell concentrations 

 increasing from 5 to over 63 ppm. Cultures enriched with 

 As(III) exhibited similar uptake; however, enrichment with 

 dimethylated arsenic (DMA) caused no significant uptake of As. 



The As speciation in the culture media changed significantly 

 during the course of the experiment in cultures that had been 

 enriched with As(V) or As(III). Addition of DMA caused no 

 changes in As speciation other than those caused by the addition 

 itself. 



The continuing investigation of organic pollutants in the Gulf 

 of Mexico has established that phthalic acid ester plasticizers 

 (PAES) are a new class of marine pollutants. Phthalate esters 

 are found in virtually all samples from the Atlantic Ocean and 

 the Gulf of Mexico. For example, samples of water, sedi- 

 ment, and air from the Gulf of Mexico were found to con- 

 tain di-(2-ethylhexyl)phthaIate (DEHP) at concentrations often 

 higher than the well-known PCBs and DDTs. However, the 

 concentration of PAES in biota was lower than that of PCB or 

 DDT, suggesting that biological degradation may be a significant 

 removal mechanism for phthalates in the marine environment 

 (fig. 6). 



Preliminary analyses show that as much as 70 percent of the 

 phthalates in the Gulf of Mexico have been transported via the 

 atmosphere. The rates and mechanisms of organic pollutant 

 transport depend on the class compound. For example, organic 

 pollutants are transported to the atmosphere both in association 

 with particles and as a vapor. PCBs and DDTs are transported 

 primarily in the vapor phase; however, DEHP appears to be 

 distributed nearly equally between the vapor and particulate 



EQUIPMENT RACK 

 (POWER AND PROPULSION 

 EQUIPMENT) 



AIR 

 CURTAINS 



WIND 

 SCREENS 



ADJUSTABLE 

 FRITS 



TRUNCATED PYRAMID 



Figure 3. — The Bubble Interfacial Microlayer Sampler (BIMS) suspended between the twin hulls of a 4-meter long catamaran. 



