and 0.19 percent DTDP. The sum is nearly 0.5 percent on a dry- 
weight basis. 
The total content of organic phthalate esters in Tenneco 
Pond can only be guessed at since the vertical concentration 
distribution was not determined in this work. For a depth of 
0.04 m, the Tenneco Pond sediment volume for 40 x 10^ m^ of sur¬ 
face area is 1.6 x 10^ m^, or roughly 6.4 x 10^ kg on a weight 
basis. The measurements are thus compatible with the presence 
of 960 kg of DEHP, 900 kg of DIDP, and 1200 kg of DTDP, or a 
total of about 3,000 kg of these three organics. 
As discussed earlier, the State discharge permit allows 
Tenneco to release total organic extractables at a rate of 
2000 kg/year. It would appear that Tenneco discharge may be 
operating rather near the permit, depending on where the 
measurement is made: plant discharge or outfall from the dam. 
The pond is clearly acting as a secondary waste treatment facil¬ 
ity, and it is obvious that less organics have been flowing out 
of the pond than those that enter. The DBP content is low be¬ 
cause Tenneco has rarely manufactured it. 
The fact that the pond levels are now high should be inter¬ 
preted as a warning. As the pond sediment becomes increasingly 
saturated with these organics, they may eventually move out into 
the Morgan Creek conduit. Since the linear flow rates are much 
higher and the creek bed is rather narrow, it is important to 
consider the eventual saturation of the present sorptive capacity 
of the pond sediment. At a future time the allowed Tenneco dis¬ 
charge, 2000 kg/year, may become more likely to make a direct 
transit from the factory site to the Chester River, and to pos¬ 
sibly high localized concentrations in the river sediments. If 
this situation is allowed to continue without any further re¬ 
straint, one can not help but visualize a more pessimistic 
future for the sediment beds in the Chester River. 
The Chester River sediments exhibit ranges of 0.020 to 0.064 
ppm for DEHP and 0.23 to 0.85 ppm for DBP. Stations 3, 4, 5 and 
6 were deliberately localized at the apex of the oyster mortality. 
The data are not marked by major apparent differences from the 
site "R" at the river mouth. Since healthy oyster beds have been 
maintained downstream of sited 4-6, there is no framework pro¬ 
vided by the present data to assign alkyl phthalates as causally 
related to the 1973-75 oyster mortality. Of course, this is 
purely circumstantial reasoning, and the results can not be used 
to rule out the possibility. However, no oyster samples were 
saved . 
