A massive buildup of alkyl phthalates manufactured by Tenneco 
was found in Tenneco Pond immediately adjacent to the factory 
waste water discharge plant. The levels show clearly that the 
pond sediments are serving as a sink, i.e., as a secondary waste 
treatment facility. 
Experimental measurements of Chester River sediments show no 
significant differences between the mortality zone and the Ches¬ 
ter River mouth where reasonably healthy oyster growth persists. 
The results for DBP and DEHP are very nearly identical in these 
regions in the Chester River: 0.02-0.85 ppm with average values 
of DBP (0.5 ppm) and DEHP (0.05 ppm). The DEHP/DBP ratio is 
0.1 + 0.07. 
The Tenneco Pond results are quite different: DEHP (1.5 x 
10^ ppm) and DBP (0.2 ppm). Tenneco has rarely made DBP. The 
difference in the DEHP/DBP ratio alone suggests that the alkyl 
phthalates in the Chester River may originate from Tenneco as 
well as other possible sources. Moreover, the estimated possible 
accumulation in Tenneco Pond—10^ kg of alkyl phthalates—sug¬ 
gests that the pond functions in part as a waste treatment 
facility. 
The greatest threat seems to be that the Tenneco Pond may be 
nearing the saturation state that it must reach eventually. In 
that case, one can confidently forecast a serious accumulation 
of the alkyl phthalates that will in time spread out into the 
Morgan Creek area. 
MICROBIAL TRANSFORMATION OF TIN 
Examination of physiochemical data (pH, temperature, 
salinity, dissolved oxygen) from four estuarine and three fresh¬ 
water sites shows only low dissolved oxygen near the bottom as a 
potential contributor to oyster mortality in the Chester River. 
All sediment and water samples examined contain microorga¬ 
nisms resistant to inorganic tin; resistant organisms comprised 
as much as 55 percent of the total aerobic, heterotrophic popu¬ 
lation detected. Most of the water and sediment samples con¬ 
tained organisms resistant to the organotin compound, 
dimethyltin chloride; such organisms comprised as much as 17 
percent of the total aerobic, heterotrophic population detected. 
Microbial populations are more sensitive to organotin than 
to inorganic tin. 
Microorganisms capable of converting inorganic tin to 
volatile tin compound(s) are widely distributed in the Chesa¬ 
peake ecosystem. 
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