the grain size and what have you. In our studies we used several 

 methods. The standard organic carbon test in dichromate titra- 

 tion, combustion, and also a rather simple method using hydro- 

 gen peroxide and digesting the material. We found variations 

 from zero in the sand, which is rather obvious, to as high as 

 33 percent in the marsh where Distichlis is quite heavy. It 

 would grade all the way through there with an average of perhaps 

 about 14 percent organic material. Sediments on the marsh 

 were mainly silts, that is, greater than 50 percent silt and ac- 

 tually mainly silt and clay with fine sand mixed in. They are 

 firm. From what Dr. Redfield says I would guess that they are 

 similar to the Barnstable silts. 



Redfield: This is Newport ? 



Stevenson: Newport and other marshes in the same area. They are firm 



and have little peat-like qualities such as you find sometimes in 

 New England where the organic material is very high. 



Oppenheimer: I would like to say that when you are working with marine sedi- 

 ments you have to be very cautious about generalizations because 

 within a matter of one or two feet you will find environments 

 changing almost abruptly from perhaps a sand and shell mixture 

 to clay. The organic content and the amount of available space 

 for the organisms that may live in the sediment will vary pro- 

 portionately to that environment. So if you go out in the field 

 and make a survey over a pond or an area, and you take random 

 samples, this is by no means a good distribution of the organ- 

 isms which might exist. I have taken samples within three 

 inches of each other that varied in population by over 100 per- 

 cent and one may have only one species of microorganism, 

 namely bacteria, in the clay. The next adjacent spot, which 

 may be sand, will have flagellates, ciliates, amoebas, and dia- 

 toms just within a matter of a couple of inches. Again sand is 

 a rather confusing term. It is supposed to be nonproductive. 

 Very few people have really looked at it with the thought in mind 

 that sand is porous and therefore it may have a steady state or- 

 ganic production which is higher than clay, but purely by turbid- 

 ity currents which might be going through the sand you will find 

 that the organic material is washed away, while the organic mat- 

 erial in the clay remains. So, productive -wise you might find 

 that the sands are far more productive of organic material than 

 the clays although it does not appear that way in nature. 



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