Vol. 16—1962 - NorthEastern Weed Science Society

TABLEIII
Threshold Taste and Odor Concentration ot Various Phenolic' ,
Compounds(a) !
Component Geometric Mean Threshold-ug/l
~ ~
Phenol
2-CP
4-cp
2,h.-DCP
2,6-DCP
2,4,6!~TCP
-,..1000
4
"'1000
8
2
"'1000
(a) a~ter Burttschell e~ ~l (4)
7 1000
2
250
2
3
~1000
The data also indicate th~t any 2,4-DCPpresent in a lake
treated with 2,4-D would be there primarily'~san impurity ~roin
the ~ormulation. There is no evidence from this study to
suggest that,an appreciable oonoentration 0~'2,4-DCP would
arise ~rom the biological degradation o~ 2,4--D. I~ 2,4-DCP
is an intermediate degradation product, then apparently it
decomposes at about the same rate as 2,4-D.
The data also show that2,4-D does not Persist ~or any
appreciable length o~ time. This compound apparently reaches
its peak concentration soon a~ter application whereupon it ,
decreases to levels that reach ~ sensitivity o~ the analytical
method. In addition, very small amounts o~ 2,4-D, 13-50 ug/l, ,
were detected in the "~ree ~lowing" portion o~ the lake that .
came ~rom the initial 1.34 mg/l dosage. ThIs'may be an empirioal
reason why, in this particular study, the degradation o~ small
amounts o~ 2.4-D is not a signi~icant source o~ 2.4-DCP.
This study, perhaps, presents a more realistic picture of
the occurrence and persistence o~ 2,4-DCP in a 2,4-D- treated ,
lake than the carboy study reported here last'year (6). At '
that time, there was evidence that 2,4-DCP oouurred and
persisted at levels high enough to produce taetes and odors
according to the data o~ Burttschell. Since this investigation
was limited to one lake and one type o~ ~ormulation, however,
additional ~ield studies are needed to show tme.'e~fect o~
various concentrations of 2,4-Dand of other types of formulations
on taste and odor water quality. The previous carboy study
showed that the ooncentir-atn orr iot' 2,4-DCP impur,i ty varied considerably
with type and concentration of ~ormulation (6). The