Vol. 15â1961 - NorthEastern Weed Science Society
Vol. 15â1961 - NorthEastern Weed Science Society Vol. 15â1961 - NorthEastern Weed Science Society
396. WHATHAPPENS TO PHENOXYHERBICIDES .WHENAPPLIED TO A WATERSHEDAREA by A. W. Winston, Jr. and P. M. Rittyl '. Water supply people responsible for maintaining reservoirs of wholesome water frequently ask about. the effects on water , quality when brush in the surrounding watershed areas is chemically sprayed. What are the breakdown products and how" might they affect water supplies are two of the questions sanitary engineers ask concerning phenoxy herbicides. No discussion will be made here regarding the direct toxicity of 2,4-D and related materials. The wide use of 2,4-D, 2,4,5-T and similar compounds over many years now provides excellent practical assurance of the lack of toxicity. Discussed here will be the products of decomposition by soil microflora and their effects on water supplies. A. MICROBIAL DEGRADATION Bacterial decomposition of 2,4-D, 2,4,5-T, silvex and related chemicals is well reported in the literature. At least eight species of bacteria are known to feed actively on chlorinated phenoxy herbicides. Corynebacterium sp. (8) decomposed 80%of a 1,000 parts per million (ppm) concentration of 2,4-D in four hours, releasing chlorine as the free chloride ion. Bacterium globiforme (1), which is readily found in garden and woods soils, Flavobacterium aguatile (5) and F. peregrenum (12), two species of Achromobacter (2, 12), and a Mycoplana sp. (14) all have been identified as capable of destroying phenoxy compounds. Work conducted by the senior author of this paper shows still another species of bacterium that feeds actively on phenoxy compounds. This bacterium has been identified as PseUdomonas cruciviae, and is one whose source of isolation and habitat 1s soil (3). P. cruciviae fed equally as well on 2,4 dichlorophenol, pentachlorophenol, and unsubstituted phenol. The hypothesis has been made that soil and water bacteria would convert 2,4-D, 2,4,5-T and related chemicals back to diand trichlorophenols (2,4). Both of these free phenols can cause taste and odor problems in extremely low concentrations. A study was undertaken to evaluate this hypothesis and to positively determine the end decomposition products formed after exposure to bacterial action. 1 The Dow Chemical Company, Midland, Michigan.
- 397. B. PROCEDURE Laboratory apparatus used in these mainly of a source of supply of phenoxy (since biological oxidation by previously bacteria occurs generally under aerobic experiments solutions, mentioned conditions) consisted an aerator, species of a settling chamber and a proportioning pump to provide continuous feed at a set rate. The effluent solutions were collected and chemically analyzed to determine components or degradation products. Seeding of the aerator to obtain phenol digesting bacteria was done in two ways. Activated sludge from an industrial waste treatment plant which treats both sanitary and industrial wastes" provided bacterial "seed" for half of the test equipment. However, since bacteria which decompose these compounds are reported to be found generally in nature (3, 6, 9, 13), a collection of soil samples was gathered from a typical watershed area and used for comparison in the other half of the laboratory setup. These watershed soil samples were taken from areas on which no prior application of any herbicides has been made. C. RESULTS Known amounts (i.e., 55 ppm) of phenoxy herbicides were fed to the influent of the systems. After 3D-hour exposures to the bacterial CUltures, effluent samples were removed and exhaustively analyzed. Beside odor and taste threshold tests, the Gibbs test to determine free phenols with a sensitivity of 10 parts per billion (ppb) was used. Furthermore, to increase this sensitiVity, after color formation with the Gibbs method, a further solvent extraction was made so as to concentrate color and thus increase sensitivity of the test. With the analytical tests then having a sensitivity of 0.5 ppb, no free phenols were detectable. Microflora from either the general waste seeding or from watershed soil samples had decomposed the phenoxy compounds to carbon dioxide, inorganic chlorides and water. A quantitative release of the chloride ion had occurred during the bacterial decomposition (II). In the effluents there was no detectable dichlorophenol nor trichlorophenol residue. The oxygen consumption was that which theoretically would be required to affect complete oxidation. Free phenols as such were also introduced into the system for further tests on biological oxidation. The phenols were reduced in a similar manner. Confirmation of this work with regard to 2,4-D has been reported by TIogoff and Reid (8). Their summary states, "An organism • • • • • • Corynebacterium sp. • • • • decomposes 2,4-D acid in relatively large amounts in synthetic medium. Indications are that complete destruction of the molecule follows ring rupture."
- Page 346 and 347: 346 • .Absornt:j.Qn Qn Exchange R
- Page 348 and 349: 348. The' chrona tog ram."WaS first
- Page 350 and 351: 350. PROGRESSREPORTON A STUDYOF THE
- Page 352 and 353: 352. 7. Fluctuating warm and cold w
- Page 354 and 355: 354. A clos.e correlation was found
- Page 356 and 357: 356. 1 THE ANATOMICAL NATUREO:BTHE
- Page 358 and 359: 358. The 2,4,5-TP was most effectiv
- Page 360 and 361: Table I. Effect. of Pre-emergence T
- Page 362 and 363: INTRODUCIIOB: THEEFFECTOF WEEDCOMPE
- Page 364 and 365: 1";. 1958 JFab1e I (cont ' d) Treat
- Page 366 and 367: 366. fiE USE OF FENACFOR QUACKGRASS
- Page 368 and 369: 36$. SUMMARY: Based on a I).umber o
- Page 370 and 371: - Table 1. Chemicals and Rates Used
- Page 372 and 373: 372. On spring plowed plots I where
- Page 374 and 375: Table 1. Treat.ments Used and Stand
- Page 376 and 377: 37t. PRELIMINARYRESULTSONTHE CONTRO
- Page 378 and 379: 378. CHEMICAL TREATMENTS FORTHECONT
- Page 380 and 381: Table ;. Visual RatiDgs and Stand C
- Page 382 and 383: ANN11AL WEEDCONTROL IN SILAGECORN1
- Page 384 and 385: TABLEI. field Corn tiead Control an
- Page 386 and 387: Sunderiand,' Mass..Experiment: In t
- Page 388 and 389: ) ) BBLB I. QuackgT88S Control in F
- Page 390 and 391: TABLEIII. Quackgr888 Control in Fie
- Page 392 and 393: 392. herbicides. In senerel."we.had
- Page 394 and 395: 394. RESULTS§e PISCUSSION In Augus
- Page 398 and 399: D. TASTEAND ODORSTUDIES Taste and o
- Page 400 and 401: herbicides produces aquantit.at.ive
- Page 402 and 403: 4('2. • A DECADEOF BRUSHCONl'ROL
- Page 404 and 405: areas, fre1.uently the crews l'UIrL
- Page 406 and 407: 406. During June and July 1959 a pr
- Page 408 and 409: 408. Numerous chemicals have been u
- Page 410 and 411: " A Progress Report on Urab * Brush
- Page 412 and 413: 412.
- Page 414 and 415: 414. Urab is an effective chemical
- Page 416 and 417: 416. application. Atrazine has a wa
- Page 418 and 419: 418. COMPARISONOF TECHNIQUESANDSPEC
- Page 420 and 421: Table I - Results of chemicals appl
- Page 422 and 423: 422. Results and Discussion Data fr
- Page 424 and 425: 424. THE CONNECTICUT ARBORETUM RIGH
- Page 426 and 427: 426. (Kalmia angustifolia) ,huckleb
- Page 428 and 429: 42$. TABLEI (cont'd.) Technique For
- Page 430 and 431: 43". by Leonard and Crafts (15) mos
- Page 432 and 433: 432. awareness of the need for good
- Page 434 and 435: 434. RECOMMENDAT:I"'NS FOR THE USE
- Page 436 and 437: 436. The recommended materials for
- Page 438 and 439: 438. NATURALANDSCAJ:'ING WITHHERBIC
- Page 440 and 441: 440. STATEHIGHWAYHERBICIDE POLICIES
- Page 442 and 443: 442. There is a matter of judgment
- Page 444 and 445: 444. DATAON STATEHIGHWAYHERBICIDE P
-<br />
397.<br />
B. PROCEDURE<br />
Laboratory apparatus used in these<br />
mainly of a source of supply of phenoxy<br />
(since biological oxidation by previously<br />
bacteria occurs generally under aerobic<br />
experiments<br />
solutions,<br />
mentioned<br />
conditions)<br />
consisted<br />
an aerator,<br />
species<br />
of<br />
a settling<br />
chamber and a proportioning pump to provide continuous feed at<br />
a set rate. The effluent solutions were collected and<br />
chemically analyzed to determine components or degradation<br />
products.<br />
Seeding of the aerator to obtain phenol digesting bacteria<br />
was done in two ways. Activated sludge from an industrial<br />
waste treatment plant which treats both sanitary and industrial<br />
wastes" provided bacterial "seed" for half of the test equipment.<br />
However, since bacteria which decompose these compounds are<br />
reported to be found generally in nature (3, 6, 9, 13), a<br />
collection of soil samples was gathered from a typical watershed<br />
area and used for comparison in the other half of the laboratory<br />
setup. These watershed soil samples were taken from areas on<br />
which no prior application of any herbicides has been made.<br />
C. RESULTS<br />
Known amounts (i.e., 55 ppm) of phenoxy herbicides were fed<br />
to the influent of the systems. After 3D-hour exposures to the<br />
bacterial CUltures, effluent samples were removed and exhaustively<br />
analyzed. Beside odor and taste threshold tests, the<br />
Gibbs test to determine free phenols with a sensitivity of 10<br />
parts per billion (ppb) was used. Furthermore, to increase this<br />
sensitiVity, after color formation with the Gibbs method, a<br />
further solvent extraction was made so as to concentrate color<br />
and thus increase sensitivity of the test. With the analytical<br />
tests then having a sensitivity of 0.5 ppb, no free phenols were<br />
detectable. Microflora from either the general waste seeding or<br />
from watershed soil samples had decomposed the phenoxy compounds<br />
to carbon dioxide, inorganic chlorides and water. A quantitative<br />
release of the chloride ion had occurred during the bacterial<br />
decomposition (II). In the effluents there was no detectable<br />
dichlorophenol nor trichlorophenol residue. The oxygen consumption<br />
was that which theoretically would be required to affect<br />
complete oxidation. Free phenols as such were also introduced<br />
into the system for further tests on biological oxidation. The<br />
phenols were reduced in a similar manner.<br />
Confirmation of this work with regard to 2,4-D has been<br />
reported by TIogoff and Reid (8). Their summary states, "An<br />
organism • • • • • • Corynebacterium sp. • • • • decomposes<br />
2,4-D acid in relatively large amounts in synthetic medium.<br />
Indications are that complete destruction of the molecule follows<br />
ring rupture."