PESTICIDES IN SOILVILY, COI

DO -NOT ILENS-OVE

DDT Residues in Forest Floor and Soil After Aerial Spraying, Oregon-1965-68 '

R. F. Tarrant, D. G. Moore, W. B. Bollen, and B. R. Loper

ABSTRACTOne month after aerial application of DDT (12 oz/acre) toan eastern Oregon forest, 3 oz/acre of DDT residues (DDT,its isomers and metabolites—DDD, DDE, p,p'-DDT, ando,p'-DDT) were detected in the forest floor; 3 years later,the DDT content had decreased by more than 50%, and hadnot leached into the surface mineral soil.

At the time of spraying, water from two streams drainingthe sprayed area had a total DDT content of about 0.3 ppb.This low concentration decreased rapidly to levels belowlimits of analytical detection. No effect of the spraying wasnoted on soil microbial populations, nitrification mte, oramount of nitrate nitrogen in the soil.

Of the I2 oz of DDT applied per acre, about 26% reachedthe ground surface initially; and over 36 months, about 6%more was brought to the ground in litterfall. Thus, approx-imately one-third of the sprayed chemical reached the forestfloor. The need for more efficient aerial methods of chemicalapplication is evident.

IntroductionOnly a few studies have been concerned with residuesof DDT, its isomers and metabolites, in the forest en-vironment. Woodwell (41) determined DDT residuesin a forest in New Brunswick, Canada, which had beensprayed between 1952 and 1958 with a total of 4 lb/acreof DDT. He concluded that the maximum residue per-sistence time in forest soil would he 10 years and thato,p'-DDT was leached into the subsoil. Woodwell andMartin (42) reported that DDT residues in heavilysprayed forest soils in Maine and New Brunswick in-creased over a period of 3 years after final spraying.These authors hypothesized that DDT residues persistin the forest canopy and are carried to the soil by rainand litterfall.

From the Pacific Northwest Forest and Range Experiment Station.U. S. Department of Agriculture. Forest Service, Corvallis, Oreg.97330.

VOL. 6, No. I, JUNE 1972

Yule (43) stated, however, that Woodwell's hypothesisof differential weathering and preferential retention ofo,p'-DDT by New Brunswick forest soils is untenable.He concluded from a study in the same locality thatabout 16% of the DDT originally applied still remainedin surface soils after almost 20 years, but mainly in theform of the most toxic isomer, p,p'-DDT. He furtherdemonstrated that the acidic, highly organic, forestsurface soils held these DDT residues unavailable intoxic amounts to soil insects.

DDT residues were also measured in a northern Penn-sylvania forest soil, 380 days after aerial spraying ata rate of 0.5 lb/acre (9). The only environmentalchange reported was a significant accumulation of DDTin the forest floor and surface soil. One year afterspraying, no measurable increase in DDT residues wasnoted in fish, crayfish, or stream sediments. Belyed (4)studied DDT residues in soils and a related food chainin northern Maine forests. He concluded that DDTwould disappear from these soils in 10-12 years. Inwestern Washington, DDT was applied to the surfaceof a gravelly soil beneath a stand of Douglas-fir [Pseudo-tsuga menziesii (Mirb.) Franco] at 0.5 and 5.0 lb/acre(29). Regardless of application rate, less than 1% ofthe DDT applied leached through the surface soil.

In 1965, an opportunity to further study DDT residuesin forests resulted from a spray project conducted bythe U. S. Forest Service between June 10 and July 1 tocontrol a serious outbreak of the Douglas-fir tussockmoth (Hemerocampa pseudotsugata McD.) in easternOregon. Helicopters were used to spray 66,000 acresof forest with an insecticide formulation of 0.75 lb oftechnical grade DDT dissolved in 0.94 qt of hydro-carbon solvent and sufficient No. 2 fuel oil to make 1gal of solution at 60° F; the application rate was 12oz/ acre.

65

A number of public agencies have already conductedsurveillance and monitoring activities to determineresidues in fish and wildlife, cattle. and forage, and toascertain public health effects from the spray project(10,35). The present study reports observations of thepersistence of the applied DDT in the forest floor andsoil and some related effects for the first 3 years afterthe spray project.

The area studied was along a 1-mile transect in theMalheur National Forest of eastern Oregon. Elevationof the area is 5,700 feet. The subhumid continental cli-mate includes dry, warm summers (>100' F maximumtemperature) and cold winters ( —20° F minimumtemperature). The daily range of temperatures insummer is often 40 to 50 degrees and the monthlyrange may exceed 60 degrees. Annual precipitationaverages about 20 inches, one-third to one-half of whichis snow. Most moisture available to plants is stored inthe soil at the beginning of the growing season, and bymidsummer soils become very dry: summer flow insmall streams is intermittent.

The soil of the study area, representative of perhapsseveral million acres of eastern Oregon forest land, istentatively identified as a member of the Klicker series.This is a well-drained, moderately fine-textured, forestedsoil developed in residuum from basalt bedrock; smallfragments of the basaltic parent material occur through-out the solum, and rock outcrops are common through-out the area. The A horizon, which may contain volcanicash, ranges in texture from silt loam to silty clay loam,with the percent clay increasing gradually with soildepth. The soils are slightly acidic throughout thesolum which ranges in depth from 15 to 35 inches.Permeability is moderate, and surface runoff is medium.Major tree species in the study area which partiallydetermine the amount of litter and duff on the forestfloor are ponderosa pine [Pin gs ponderosa (Laws).1.White fir [A hies concolor (Gord. & Glend..) Undid,and Douglas-fir [Psettchnsit,i,,a menziesii (Mirb.) Francol.

Sampling Procedures

Five 1/10-acre plots were established along the transectnearest to equidistant points where maximum uniformityof stand composition and density could be found. Withineach of the five plots, four sampling points were ran-domly selected. At each point, the forest floor over a4-sq-ft area was carefully removed, and I -qt samplesof soil were collected at each of two depths, 0 to 3inches and 3 to 6 inches, in step-like trenches. Extremecare was taken to avoid contaminating the lower samplewith material from above, and all tools were cleanedfrequently with acetone. Samples were placed in new 1-qtpaper freezer containers, stored during the day inportable cooler chests, and frozen the same day they

were collected. Samples of forest floor and soil werecollected prior to the spray project, 1 month after thespraying, and at 1-year intervals. Litterfall, throughfallprecipitation, and water samples from streams were col-lected every 6 months.

Eight trays, each with a surface area of 10.9 sq ft, wererandomly placed throughout each sample plot to collectlitterfall, and four 1-gal containers fitted with funnelshaving openings approximately I sq ft in size wererandomly located in each sample plot to collect pre-cipitation. Water samples from the east and west forksof Rattlesnake Creek within 50 feet of their confluencewere taken in I-gal containers, submerged just deepenough to prevent undue disturbance of bottom sedi-ments.

Analytical ProceduresSoil samples were air-dried, ground, passed through a10-mesh sieve, mixed, and subsampled. For samplesintended for microbial analysis. the sieve was cleanedwith 30% ethanol and flamed between collections ofeach sample. Frozen litter and forest floor samples werechopped with dry ice, mixed, and subsampled. All sam-ples, including water, were stored at 0' F until extracted.

EXTRACTION

Soils: A 100-g subsample was extracted with 41:59hexane:acetone (azeotropic) in a Soxhlet extractor for16 hours (27).

Litter and forest floor: A 25-g subsample was extractedwith acetone in a Soxhlet extractor for 16 hours.

Water: Volumes up to 4.000 ml were extracted withhexane in a continuous-cyclin g liquid-liquid extractorfor 16 hours.

CLEANUP

The soil and litter extracts were transferred to separa-tors funnels. Water was added to form a 2:1 water-acetone solution. The pesticides were partitioned intohexane b y shaking with three 100-ml aliquots of hex-ane ( /7).

The hexane extracts of soil, litter. and water were driedwith anhydrous sodium sulfate. evaporated to a smallvolume (5- to 10-m1), and transferred to a I5-g Florisilcolumn (40). The pesticides were eluted from thecolumn with 100 nil of 1:3 dichloromethane:hexane.Dichloromethane was removed by evaporation. andsamples were transferred to volumetric flasks for an-alysis.

A NALYSIS

The concentration of DDE. 0.p'-DDT, DDD, and p,p'-DDT was quantified in a MicroTek 2000 MF gaschromatograph with a I30-me tritium electron capturedetector. This system gave good individual peak resolu-tion at the following retention times: DDE, 5.2 minutes;

66

P ESTICIDES M ONITORING J OURNAL.

o,p'-DDT, 6.8 minutes; DDD, 8.0 minutes; and p,p'-DDT, 9.5 minutes. Other operating parameters were:

Column: Pyrex glass, 180 cm x 2 mm i.d.,packed with 5% QF-1 (0.7 of length)and 5% DC-11 (0.3 of length) on60/80 mesh Gas Chrom Q, precon-ditioned for 48 hours at 220° C.

Temperature: Column 185° CDetector 190° CInjector 205' C

Carrier gas: Nitrogen at 30 ml/min

Minimum residue levels- for quantitative determinationswere 0.001 ppm for soil, 0.01 ppm for forest floor andlitter, and 0.01 pph for water. Average percent recoveryand range for DDT isomers and metabolites were asfollows:

FOREST FLOORFORM OF SOIL. AND LITER WATER

DDT (PPM) (PPM) (PP"( )

DDE 99(92-103) 97(93-100) 99(98-100)o.p'-DDT 82(71-99) 99(96-100) 98(97-100)DDD 82(78-91) 85(80-94) 94(93-95)p.p'-DDT 97(92-100) 94(90-97) 99(98-100)

NOTE: ( ) range.

CONFIRMATION

It is most necessary to positively identify any apparentDDT determined by gas-liquid chromatography (GLC),especially in samples of materials to which no knownDDT application was made. A number of industrialpollutants are similar to DDT in structure and prop-erties and can interfere with the detection or identifica-tion of DDT (19,22,28,30,31); some naturally occur-ring plant or soil substances may also he potentialsources of analytical error in determining the presenceof chlorinated hydrocarbon compounds (/4,20). Toconfirm apparent DDT residues in this study, abouthalf the samples were analyzed by GLC with a chloride-specific, microcoulometric detection system (InfotronicsInstrument Corp.). This step confirmed that substanceswith the same retention time as the DDT standardsdetected by the electron capture detector did containchlorine, but did not rule out the possible misinterpreta-tion of polychlorinated biphenyls (PCB's) as DDTisomers and metabolites. Therefore, all samples analyzedwith the microcoulometric detector were hydrolyzedwith alcoholic potassium hydroxide which would chem-ically alter DDT and DDD, but not PCB's (17).Hydrolyzed samples were then re-analyzed by bothelectron capture and microcoulometric detection sys-tems. DDD, o,p1-DDT, and p,p'-DDT peaks disappearedafter hydrolysis, indicating that PCB's were not presentin detectable qualities and that the quantitative measure-ment of DDT isomers and metabolites by the electroncapture detection system was correct.

VOL. 6, No. I. JUNE 1972

The mass spectrophotometer provides the most positivemeans of identifying pesticides in biological samples;but in this study, only a few forest floor samples con-tained sufficient DDT to use this instrument. Two com-posite samples of forest floor from two different plotswere extracted and purified for this particular analysis.The DDT isomers and metabolites were separated bychromatography of the final hexane extract on 500-p,silica gel H thin layer plates developed with 4:96 ben-zene:hexane. DDT standards were co-chromatographedon both edges of the 20- by 20-cm plates. Afterdevelopment, a 15-cm strip in the middle of the platewas covered, and the DDT standards were located byspraying the edge of the plate with 0.5% silver nitrateand exposing to UV light for 15 minutes. The o,p1-DDT,p.p'-DDT, and DDE were scraped from the appropriatesection of the center of the plate, extracted from thesilica gel with hexane, and analyzed by gas chroma-tography (electron capture detector). The pesticidesseparated by the thin layer method had the same re-tention times as the standards.

Extracts containing the individual pesticides were in-troduced into a Model CH 7 (Varian Mat. Bmg. H.)mass spectrometer with a direct inlet probe. The massspectra for o,p'-DDT, p,p'-DDT, and DDE isolatedfrom the forest floor samples agreed with spectra ofappropriate standards and with published spectra (34).Sample spectra compared with published PCB spectra(3) indicated no PCB's present in the isolated pesticides.All confirmation steps gave positive evidence that thesubstances isolated and measured were indeed DDTisomers and metabolites and that PCB's were not presentin detectable quantities.

MICROBIAL ANALYSIS

The number of bacteria in soil was estimated by platingsterile tap water dilutions of soil on sodium albuminateagar; mold counts were made on plates of peptone-glucose-acid agar (37). In each case, five plates werepoured of each dilution: 1:50, 1:500, and 1:5,000 formolds; 1:5,000. 1:50,000, and 1:500,000 for bacteria.Mold colony counts were made on plates showingapproximately 30 to 100 colonies after 3 days' incuba-tion; major genera were differentiated as mucors, Peni-cillium, and Aspergillus after 3 to 7 days. Total bacteriaand Streptomyces were counted on plates showingcolonies in the range of 50 to 300 after 10 to 14 days'incubation; Streptomyces were differentiated and theirnumbers expressed as a percentage of the total count.Incubation was 28° C.

Nitrite and nitrate were determined colorimetrically bythe diazotization (2) and phenoldisulfonic acid (18)methods. respectively. For the nitrification study, 200ppm N was added as ammonium sulfate to 100 g of soil(oven-dry basis) in 1-pt bottles. Moisture was adjusted

67

3.00 1.0re.1

y4 Mineral Soil 0-to depth2.50 III Mineral Soil 3- 10 I, inch depth

2.00

0

1.5

1 . 0 0

0.5

',71771■ r73.—12 24

Months Aft,- Spraying.16

to 50% of water-holding capacity, and the bottles werecapped with polyethylene film and incubated for 30 daysat 28° C. Distilled water sufficient for a 1:5 dilutionwas then added, and the samples shaken for 15 minutes.After pH was measured, nitrite and nitrate in thesupernatant were determined.

Results and DiscussionFOREST FLOOR SAMPLES

A very small amount (0.13 ppm) of "apparent" totalDDT residues (p,p'-DDE, p,p-DDD, o,p'- and p,p'-DDT) were found in prespray samples of the forestfloor (Table 1); this was not confirmed as DDT, itsisomers and metabolites by means other than GLCbecause of its insignificant contribution (<0.01 oz/acre) to the totals found after spraying. One monthafter spraying, concentration of total DDT in the forestfloor was slightly more than 7.5 ppm (Table 1), or 3.08oz/acre (Fig. 1). Thus, an estimated 26% of theapplied DDT (12 oz/acre) reached the forest floorshortly after spraying. DDT residues in the forest floordecreased steadily with time, and at the end of 3 years,more than half the DDT originally added had disap-peared. Volatilization, chemical or photochemicaldegradation, and bacterial decomposition are possibleremoval mechanisms ( /2).

TABLE I. Concentration of DDT isomers and metabolitesin the forest floor before and after aerial spraying,

Oregon-1965-68

MONTHSAFTER

SPRAYING

RESIDUES IN PPM ON A DRY-WEIGHT BASIS

p,p'-DDE o,p'-DDT p,p'-DDD p,p'-DDTTOTALDDT

0 .008 .025 .008 .089 .1301 .190 1.294 .348 5.708 7.540

12 .214 .957 .352 3.914 5.43724 .298 .584 .198 3.332 4.41236 .096 .473 .114 2.641 3.324

' Each va ue for DDE, DDD, o,p'- and p,p'-DDT represents theaverage of duplicate determinations on 20 replicate samples. Therelationship between concentrations of all isomers and metabolitesand months after spraying is negatively linear and significant at the5% probability level.

SOIL SAMPLES

DDT did not leach from the forest floor to underlyingmineral soil. Apparent total DDT in prespray sampleswas 0.006 ppm (Table 2, or 0.05 oz/acre (Fig. I) atthe 0- to 3-inch depth; at the 3- to 6-inch depth, totalDDT concentration was 0.002 ppm, or 0.02 oz/acre.One month after spraying, these levels had not changed,indicating that the forest floor effectively intercepted thespray solution. One year after spraying, the residue levelof total DDT in soil at the 0- to 3-inch depth was 0.26oz/acre; at the 3- to 6-inch depth, it was 0.05 oz/acre.This small difference in residues I month after sprayingand I year later was attributed to the physical actionof soil animals and, most probably, to minor, unavoid-able contamination during sampling. DDT has a solu-

FIGURE 1.—Total DDT in forest floor and mineral soilduring 36 months after aerial spraying, Oregon-1965-68

bility in water of only about I ppb (7), and thus, doesnot leach readily in soil (16,29,33). At the end of thesecond year, total DDT at the upper and lower soildepth has decreased to 0.11 and 0.03 oz/acre, respec-tively, and by the end of 3 years, was at prespray levels.

LITTERFALL SAMPLES

DDT in litterfall totaled 0.73 oz/acre over the 3-yearsampling period, about 6% of the original application(Fig. 2). DDT concentration decreased with time at agreater rate than it did in the forest floor and soil(Table 3), suggesting that photochemical decompositionand volatilization may be effective mechanisms of chem-ical degradation in tree canopies exposed to sunlight.DDT concentration is also reduced in successive litter-fall samples because of the constantly decreasingproportion of needles and twigs originally subjected tothe spray. The contribution of DDT from litterfall tothe forest floor after spraying did not contribute stronglyto total amount observed. Total loss of DDT from theforest floor over 3 years amounted to 2.46 oz/acre, morethan three times the amount brought down in litterfallover the same period.

THROUGHFALL PRECIPITATION SAMPLES

Additions of DDT to the forest floor by throughfallprecipitation were insignificant-0.02 oz/acre for the3-year period following application (Fig. 2) Concentra-tions varied with season (summer-fall vs. winter-spring)and, in general, showed a gradual decrease with time(Table 4). DDT concentrations in samples representingthe dry summer and fall months were approximatelythree times greater than those for the wet winter-spring

68

PESTICIDES MONITORING JOURNAL

RESIDUES IN PPM ON A DRY-WEIGHT BAS S 1MONTHS

AFTERSPRAYING p,p'-DDE o,p'-DDT p,p'-DDD p,p'-DDT

TOTALDDT

0 7 122 1 1, 2 4 25-30 31-36

Months After Spraying

101,20311

^ 00,01g1)1311 pre,ii 000

V %

A- A_ A 4

a.L l

TABLE 2.-Concentration of DDT isomers and metabolitesin surface soil before and after aerial spraying,

Oregon-1965-68

TABLE 3.-Concentration of DDT isomers and metabolitesadded to the forest floor in litterfall after aerial

spraying, Oregon-1965-68

0- to 3-inch depth

0 .001 .002 - .003 .0061 .001 .001 - .004 .006

12 .003 .005 - .021 .02924 .001 .002 - .009 .01236 - .001 - .005 .006

3- to 6-inch depth

0 - .001 - .001 .0021 .001 - .001 .002

12 - .002 - .004 .00624 - .001 - .002 .00336 .001 - .001 .002

NOTE: - not detected.Each va ue for DDE, DDD, o,p'- and p,p'-DDT represents theaverage of duplicate determinations on 20 replicate samples.

FIGURE 2.-Total DDT brought to forest floor in litterfalland throughfall precipitation during 36 months after aerial

spraying, Oregon-1965-68

season. Precipitation samples for the 13- to 18-monthperiod after treatment contained higher DDT concen-trations than expected relative to the amount of rainfallfor the period and the concentrations found at 6 and30 months. However, the DDT levels, their seasonalvariations, and the total range in concentrations foundin this study are consistent with normal climatologicalvariations and similar to those reported for other regions( /,36,39).

VOL. 6, NO. I, J UNE 1972

MONTHSAFTER

SPRAYING

RESIDUES IN PPM ON A DRY-WEIGHT BASIS I

p,p'-DDE o,p'-DDT p,p'-DDD p,p'-DDTTOTALDDT

0-6 .66 1.57 .44 8.65 11.327-12 .19 1.65 .30 8.18 10.32

13-18 .13 1.06 .22 5.71 7.1219-24 .15 1.07 .26 6.01 7.4925-30 .09 .62 .13 3.08 3.9231-36 .07 .47 .10 2.44 3.08

I Each va ue for DDE, DDD, o,p'- and p,p'-DDT represents theaverage of duplicate determinations on • 20 replicate samples. Therelationship between concentrations of DDT isomers and metabolitesand months after spraying is negatively linear and significant at the5% probability level in all cases.

TABLE 4.-Concentration of DDT added to the forest floorin throughfall precipitation after aerial spraying,

Oregon-1965-68

MONTHSAFTER

SPRAYINGPRECIPITATION

(MM)TOTAL DDT RESIDUE 2

(PPB )

0-67-12

13-1819-2425-3031-36

162212185455110241

.176.075.364.066.103.036

Rainfall level extrapolated from monthly climatological data forBurns, Oregon, using Mean Annual Precipitation Isohyetal Map,U. S. Weather Bureau River Forecast Center, Portland, July 1964.Total DDT residue includes p,p'-DDE, o,p'-DDT, p,p'-DDD andp,p'-DDT. DDE residue accounted for an average 6.58% of totalDDT residue and showed no statistically significant change with time.

At the end of 3 years, DDT concentrations in through-fall precipitation had decreased appreciably, but stillwere 5 to 10 times greater than levels found in samplesfrom an untreated forested area in western Oregon;however, the total amount of DDT brought down overthis period in throughfall precipitation was negligiblecompared with that part of the intended application thatinitially reached the forest floor or was deposited inlitterfall. Thus, throughfall precipitation was not a sig-nificant factor in determining the fate of applied DDTor in maintaining DDT concentrations in the forest floor.

DDT IN STREAMWATER SAMPLES

Streamwater was monitored in Rattlesnake Creek imme-diately above the confluence of the east and west forks,both of which flow from the sprayed area. The maximumtotal DDT concentration found over a period of 31/2years after spraying was 0.277 ppb; this was in a sampletaken a few hours after spraying (Table 5). This levelwas similar to those reported from North Carolina (15)and northeastern California (5) and less than thosefrom northern Pennsylvania (9) and New Brunswick(44). Most samples, including those taken 31/2 yearsafter the spraying, contained concentrations of DDTnear the lower limit of detection (0.01 ppb).

69

DATEDAYS FROM

TIME OFSPRAYING

.010

.032

.010

.010

.277

.022

.015

.104.031.028.014

RATTLESNAKE CREEKEAST FORK WEST FORK

19655/24 -306/19 -46/23 17/14 218/26 64

11/17 147

19666/7 3497/19 391

11/9 505

742869

19687/16 1,131

11/12 1,251

19677/4

11/7

TABLE 6.-Soil microbial populations, nitrate nitrogen con-tent, and nitrification rate before treatment and during

24 months after aerially spraying with DDT at12 oz/acre, Oregon-1965-68

TABLE 5.-Total DDT content of streamwater flowing fromsprayed area-before treatment and during 3 years

after treatment, Oregon-1965-68TOTAL DDT RESIDUES IN PPB

NOTE: - = not detected.Blank = levels of DDT isomers and metabolites less than 0.01ppb but greater than 0.002 ppb.

Surveillance operations by the Bureau of Sport Fisheriesand Wildlife (2.5) indicated that the DDT spraying hadlittle effect on the waters and organisms of MalheurLake, toward which Rattlesnake Creek flows. Levels oftotal DDT accumulation in the food chain of Rattle-snake Creek were very low in all components of thesampled community (8).

MICROBIAL SOIL PROPERTIES AND NITROGENRELATIONS

The small amount of DDT in the top 6 inches ofmineral soil had no significant effect on microbial pop-ulations, soil nitrification rate, or amount of nitratenitrogen (Table 6). A number of findings similar tothese are found in the literature; these reports, however.are based on laboratory studies in which DDT wasadded to soil at extremely high rates-50-2,000 lb/acre(13,21,24,26,32). Effects of pesticide residues on mi-crobes in agricultural soils are usually negligible whenthe chemicals are used at recommended field rates (6,11,23). Such field rates were usually much greater thanthose encountered in this study. Thus, it may be con-cluded that the small amount of total DDT residue insoil found after low-volume aerial spraying to controlinsects is not hazardous to soil microbes or their rolein maintaining soil fertility.

FATE OF AERIALLY APPLIED DDT

Of a total aerial application of 12 oz of DDT per acre,26% reached the forest floor initially, 6% was brought tothe forest floor in litterfall over a 3-year period, and afraction of 1% of the total was washed from the treecanopy over 3 years (Table 7). Thus, about one-thirdof the total application reached the forest floor.

SOILVARIABLE AND UNIT DEPTHOF MEASUREMENT ( INCHES )

MONTHS AFTER AERIAL SPRAYING I

0 1 12 24

Total bacteria-millions/g of soil 0-3 2.51 2.81 3.46 7.58

3-6 1.83 2.05 4.04 4.51Streptomyces-

percent of totalbacteria 0-3 15.25 23.63 27.25 63.81

3-6 13.13 19.50 35.56 34.00Total molds-

thousands/g of soil 0-3 338.19 302.88 464.69 168.313-6 93.88 33.88 323.31 35.06

Penicillia-percentof total molds 0-3 78.23 94.46 95.06 62.72

3-6 77.10 68.45 82.78 68.45Nitrate nitrogen

in soil-ppm 0-3 58.00 40.94 7.00 17.503-6 5.81 4.31 1.63 2.13

Nitrification of addedammonium sulfate-percent of total 0-3 9.59 -.56 -.50 -.17added 3-6 .27 .04 -.26 -.13

' Results of regression analysis indicated no significant rela ion be-tween soil DDT content and any of the variables measured at the5% probability level.

TABLE 7.-Total DDT deposited on the ground surface(forest floor) during 3 years after aerially spraying of

DDT at 12 oz/acre, Oregon-1965-68

SOURCE OF DDTAT GROUND SURFACE

TOTAL DDT

01/ ACREPERCENT OF

TOTAL APPLIED

Initial deposit from spraying 3.08 25.66Total deposit during 3 years from:

Litterfall .74 6.17

Throughfall precipitation .02 .01

Total, all sources 3.84 31.84

Because this study did not include direct measurementof the amounts of DDT that reached the forest canopy,the extent of chemical loss from drift during sprayingor by volatilization or degradation in the canopy afterspraying cannot be assessed. In a study in Arizona, lessthan 50% of aerially sprayed insecticides were depositedon the agricultural target during summer months (38);in the same study, the distance from the spray aircraftto the target was inversely correlated with amount ofon-target chemical application. Aircraft spraying forestlands must fly at far greater heights than those operatingover level agricultural fields. Thus, the comparativelylow amount of on-target application suggested by thepresent study is not surprising. This finding reaffirmsthat efficient methods of aerial spraying must be de-veloped in order to avoid great loss of chemical tonontarget areas.

Sec Appendix for chemical names of compounds discussed in thispaper.

70 PESTICIDES MONITORING JOURNAL

LITERATURE CITED

(I) Abbott, D. C., R. B. Harrison, J. O'G. Tatton, and J.Thomson. 1965. Organochlorine pesticides in the atmos-pheric environment. Nature 208:1317-1318.American Public Health Association. 1955. Standardmethods for examination of water, sewage, and indus-trial wastes. Ed. 10, 522 p.Bagley, G. E., W. L. Reichel, and E. Cromartie. 1970.Identification of polychlorinated biphenyls in two baldeagles by combined gas-liquid chromatography-massspectometry. J. Assoc. Off. Anal. Chem. 53:251-261.Be/yea, Glenn Y. 1967. A study of DDT residues in soilsand in a related food chain in northern Maine forests.Univ. Maine, M.S. thesis, 80 p.Bischoff, Arthur I., and Jack D. Linn. /967. Completereport on the evaluation of the effects on fish and wild-life of the Douglas fir tussock moth control project inCalifornia. Calif. Dep. Fish Game, 4 p.Boller), W. B. 1961. Interactions between pesticides andsoil microorganisms. Ann. Rev. Microbiol. 15:69-92.Bowman, M. C., F. Acree, Jr., and M. K. Corbett. /960.Insecticide solubility: solubility of carbon-14 DDT inwater. J. Agric. Food Chem. 8:406-408.Brocksen, Robert W., John D. McIntyre, and Gerald E.Davis. 1968. Accumulation of DDT in the food chainof Rattlesnake Creek. In Surveillance report, 1965Burns Project; Douglas-fir tussock moth control. USDAForest Serv., Pac. Northwest Reg., p. 12-13.Cole, H., D. Barry, and D. E. H. Frea •. /967. DDTlevels in fish, streams, stream sediments, and soil beforeand after DDT aerial spray application for fall canker-worm in northern Pennsylvania. Bull. Environ. Contam.Toxicol. 2:127-146.Crouch, Glenn L., and Randall F. Perkins (eds.). 1968.Surveillance report, 1965 Burns Project; Douglas-firtussock moth control. USDA Forest Serv. Pac. North-west Reg., 20 p.Domsch, K. 1963. Einflusse von pflanzenschutzmittelnauf die bodenmikroflora; sammelbericht [Influence ofplant protection chemicals on the soil microflora; reviewof the literature]. Berlin. Biol. Bundesanst. f. land-u.Forstwirt Mitt. 107, 52 p.Edwards, C. A. 1964. Factors affecting the persistence ofinsecticides in soil. Soils and Fert. 27:451-454.Eno, Charles P., and Paul H. Everett. 1958. Effects ofsoil applications of ten chlorinated hydrocarbon in-secticides on soil microorganisms and the growth ofstringless black Valentine beans. Soil Sci. Soc. Am.Proc. 22:235-238.Frazier, B. E., G. Chesters, and G. B. Lee. /970. "Ap-parent" organochlorine insecticide contents of soilssampled in 1910. Pestic. Monit. J. 4(2):67-70.Grzenda, Alfred R., H. Page Nicholson, John I. Teasley,and James H. Patric. /964. DDT residues in mountainstream water as influenced by treatment practices. J.Econ. Etomol. 57:615-618.Guenzi, W. D., and W. E. Beard. /967. Movementand persistence of DDT and lindane in soil columns.Soil Sci. Soc. Am. Proc. 31:644-647.Hamence, J. H., P. S. Hall, and D. J. Caverly. 1965.The identification and determination of chlorinatedpesticides residues. Analyst 90:649-656.

VOL. 6, No. 1, JUNE 1972

Harper, H. J. 1924. The accurate determination of ni-trates in soils. Ind. Eng. Chem. 16:180-183.Holmes, D. C., J. H. Simmons, and J. O'G. Talton.1967. Chlorinated hydrocarbons in British wildlife.Nature 216:227-229.

(20) Hylin, John W., R. E. Spenger, and F. A. Gunther.1969. Potential interferences in certain pesticide resi-due analyses from organochlorine compounds occur-ring naturally in plants. Residue Rev. 26:127-138.

(2/) Jones, L. W. 1956. The effects of some pesticides onmicrobial activity of the soil. Utah Agric. Exp. Stn.Bull. 390, 17 p.Koeman, J. H., M. C. ten Noever de Brauw, and R. H.de Vos. 1969. Chlorinated biphenyls in fish, mussels,and birds from the River Rhine and the Netherlandscoastal area. Nature 221:1126-1128.Martin, J. P. 1963. Influence of pesticide residues onsoil microbiological and chemical properties. ResidueRev. 4:96-129.Martin, J. P., R. B. Harding, G. H. Cannel', and L. D.Anderson. 1959. Influence of five annual field applica-tions of organic insecticides on soil biological and physi-cal properties. Soil Sci. 87:334-338.Morton, W. Mark. /968. Surveillance of Malheur Lakeand tributaries. In Surveillance report, 1965 BurnsProject; Douglas-fir tussock moth control. Glenn L.Crouch and Randall F. Perkins (eds.). USDA ForestServ. Pac. Northwest Reg., p. 11-12.Pathak, A. N., H. Shankar, and K. S. Awasthi. 1961.Effect of some pesticides on available nutrients and soilmicroflora. J. Indian Soc. Soil Sci. 9:197-200.Pionke, H. B., G. Chesters, and D. E. Armstrong. /968.Extraction of chlorinated hydrocarbon insecticides fromsoils. Agron. J. 60:289-292.Reynolds, Lincoln M. 1969. Polychlorobiphenyls (PCB's)and their interference with pesticide residue analysis.Bull. Environ. Contam. Toxicol. 4:128-143.Riekerk, H., and S. P. Gessel. 1968. The movement ofDDT in forest soil solutions. Soil Sci. Soc. Am. Proc.32:595-596.Risebrough, R. W., D. B. Peakall, S. G. Herman, M. N.Kirven, and P. Rieche. 1968. Polychlorinated biphenylsin the global ecosystem. Nature 220:1098-1102.Risebrough, R. W., P. Reiche, and H. S. Olcott. 1969.Current progress in the determination of polychlorinatedbiphenyls. Bull. Environ. Contam. Toxicol. 4:192-201.Shaw, W. M., and Brooks Robinson. 1960. Pesticideeffects in soils on nitrification and plant growth. SoilSci. 90:320-323.Smith, Virgil K. /968. Long-term movement of DDTapplied to soil for termite control. Pestic. Monit. J. 2(1):55-57.Sphon, J. A., and J. N. Damico. /970. The mass spectraof some chlorinated aromatic pesticidal compounds. Org .Mass Spectrom. 3:51-62.Strickler, Gerald S., and Paul J. Edgerton. 1970.Monitoring DDT residues on forage plants followinga forest insect control program. Pestic. Monit. J. 4(3):106-110.

71

Tarrant, K. R., and J. O'G. Tatum. /968. Organochlo-rine pesticides in rainwater in the British Isles. Nature219:725-727.Waksrnan, S. A., and E. B. Fred. 1922. A tentative out-line of the plate method for determining the number ofmicroorganisms in the soil. Soil Sci. 14:27-28.Ware, G. W., W. P. Cahill, P. D. Gerhardt, and J. M.Witt. 1970. Pesticide drift. IV. On-target deposits fromaerial application of insecticides. J. Econ. Entomol. 63:1982-1983.Weibel, S. R., R. B. Weidner, J. M. Cohen, and A. 0.Christianson. 1966. Pesticides and other contaminants

in rainfall and runoff. J. Am. Water Works Assoc. 58:1075-1084.Wood, Bobby J. 1966. Elution of dieldrin and endrinfrom Florisil. J. Assoc. Off. Anal. Chem. 49:472-473.Woodwell, George M. 1961. The persistence of DDTin a forest soil. Forest Sci. 7:194-196.Woodwell, G. M., and F. T. Martin. 1964. Persistenceof DDT in soils of heavily sprayed forest stands. Science145:481-483.Yule, W. N. 1970. DDT residues in forest soils. Bull.Environ. Contam. Toxicol. 5:139-143.

(44) Yule, W. N., and A. D. Tomlin. 1970. DDT in foreststreams. Bull. Environ. Contam. Toxicol. 5:479-488.

Reproduced by the FOREST SERVICE, U. S. Departmentof Agriculture, for official use

from thePesticides Monitoring Journal,

Vol. 6, No. 1, June 1972

72

P ESTICIDES M ON ITORING J OURNAL

*U.S. GOVERNMENT PRINTING OFFICE: 1972-796-455/8 Region No. 10

IJ ; •■;., • !- could Irc tla ,r lor a plant to convert a,i• kilo a lcm.: on. r IH , Is -Mild) are sensitive seiisitiv1 to 2,4-1)11

tHly !ad, the Tietive.":171-1/11 to active 24-1).". II; ; t this convei •joil and

hoe ,. ths I; e: • d 1)y the

(ii'.con‘. ; ! I , • I I • convcH:I

c• s•,1 ' • 1i

" : ••SelcCtVity :10 11(" : • ' I'environmental faetor;,,

'iktCflt 1above, can 1);2. destroyci hy l . st tha.;•••i tio;i1over the peas 01 from \v 'id i(i ii, 51 0 ay cause blov,:ii-a s;;;•1 todarna;,,,i due \vairy cuticle on the ;caves,id ptfuji into the plant may hein fluClir-ri cl ' IlIII1Llably by 1110 (-.;: \vetting agents in fl y) solutioi-i.Tempciattne eac, have a VCiy toiLed eli-v 00 11,,s moveurc h t, and thaactivity of the heibicid: vii' in a plant. This may result in ieduccdselectivity betwe,2n two plant spacicr:.

From the mouthwash US:I to tlic; fins 'sr applying att;zine, to his CON1,.010 SeleetiV o. 115 ton or be highly belic .m1 to society.knowledge must continually 1);:::),JI.It in OrC1(..',Y to oust Cfri-;CtiVely inc theselective pi-opei Oft of nun Letbieides.

Robert 1. Twialit

1:()Ie..1.ty Science:, 1.-.11to,toory

U. S. ho;est

011 ts till :f It, S I

"Pei is 11,c tendency ol a cheinl, cc;mpound

tinaltc;red on prsPnc of ,tic)

(if applieation Inc thod and II: A C, Of

(1Cter11; 1: 1 1iI:', i i th of Pe,si;t•sncc of

given elieinicA canno t be sitiod 10 (roc alOe on 11-(.; la1I (,1:1•-.11,,f,

use in dissimilarIn a papei included ii the pioceeclins of this course, Norris (/)

"persistence" as t1)(! ChenliC;11 C(M -::i; 0 1:11C.1 to

unaltered fonn. li e also covered M. some detnil the

cletennine pet

In this plesentstion 1 will sternmeii7.0,

Several insccIicides and ineibcid:sr oft: tit 1. 1: y •

fol-esl. s. Result ,: of thess: field and laotatc•ry studies are m r..s t, valuable lu

assessing the cluthoninente,1 eft- I' of cc y ,•;Tiic 1 t.1,-,'(.1

forest production.

132

Pek : sisicnce of Two Inccticides inOi-egon Fore.sts

DDT

The largest all-hel i c:rptet insect spray pojerI ei,er cot:ducted I,:

U.S. Forest SCIVii ,-2 \ `,.Y• osn betw:en Jut: 10 :IA T'1 ) id,

eastemmm Oregon. To C 0Iki 0 .. tious outht. :t 1., of

moth (//rP:eroc;s:::1) M:D.), t-,o.(HOOsprayed with I)1;; the tale of 12 ounces per 0crc„

since shor t ir P i, t he see hun g S t.udicd per •ri ,:s ,

aerially 111)f in the forest floor and soil (111. A cc's

(0.13 pp111) of "apparent - DDT \\as found in pcsic.,,) s.:

forest floor (Table 1). One month after sprayin: co-csnitratici

the forest floor was slightly mote than 7,5 ppm. 11,iseri on v. I:ht

1

5 4ici;les Pest ea, mitkof a „ ,14 .1ef1 Fo yos, r.

t3,41e fek, . ivy s *le 0 ,1 CoRvef 47

3-6-inch thpth01

122436

Table 1. Concentration of total DDT in the forestfloor before and after aerial spraying.

Months TotalAftel

DDTSpraying (p 1-)111)

0 0.1301 7.540

12 5.43724 4.41236 3.324

forest floor, this concentration amounted to 3.08 ounces per acre. Thus,about 26 percent of the intended DDT application of 12 ounces per acrereached the forest floor shortly after spraying.

DDT in the forest floor decreased steadily with time. At the end of thethird year after spraying, more than half the DDT originally added to theforest floor had disvpcared. Mechanisms of removal of DDT fioin theforest floor may include volatilization, chemical or photochemicaldegradation, w • hacterial decomposition.

DDT did no: leach from the forest floor to underlying soil (Table 2).Concentratioi; app-irent DDT in prespray samples was 0.006 ppm at the

Tab' 2. — Concentration of total DDT in sut facesoil before and after aerial spraying.

•Months TotalAke! DDTSpraying (ppm)

0 0-3-inch depth

0.006.006

12 .02924 .01236 .006

0-3-inch depth and about 0.002 ppm at 3-(.1 inches. One month oftenspraying, these DDT levels had not changed, indicating that- the fore ::,tfloor effectively intercepted the spray solution. One year after spraying,DDT in the surface soil was at 0.029 ppm and in the lover sod, 0.006ppni. This small increase is attributed to the physical action of soil animalsand, most probably, to minor, unavoidable- contamination duringsampling. 1)])T lies a solubility in water of only about I ppm (2, 8, 9).

At the end of the second year, DDT had (L.:creased to 0.012 ed 0.003ppm, respectively, in the upper and lower ■,;;j1 depth, By the era- of 3

years, DDT in mineral soil was at presprayDDT concentration in litterfall decrefsod v i ii time a greate, late

than it did in the forest floor and soil (fable 3). Phooeliemicaldecomposition and volatilization may bo ef fective ine,:hanirlif., of cheti-ilealdegradation in tree canopies expu.A t ai sunlialit. DDT concentr:.:tionalso reduced in successive litterfall because of the constantlydecreasing proportion of medics and tv..1s originally subjected to the,spray.

Table 3. — Concentration of total DDT addedto the forest floor in litterfall afteraerial spraying.

Months Total

After DDT

Spraying (ppm)

0-6 1L327-12 10.32

13-18 7.1219-24 7.4925-30 3.9231-36 3.08

The input of DDT to the forest floor from lilted -all after spraying didnot contrilite strongly to total amount observed. Total loss of DDT f7o;11

.002 the forest floor over 3 years amounted to -'.46 ounces per acre, 11111:

.002 three times the amount brought down in litterfall mer the same period.

.006 Additions of DDT to the forest floor by throughfall precipitation were

.003 insignificant--0.02 ounce per acre for the 3-year period follow inz,

.002 application. Concentrations varied with season (summer-fall vs. winter-

134

135

spring) and, in gencrttr, showed a gradual ch'creasa with limc (Table 4).DDT concentratioiLt IT samples riutest.ttnting the dry summer and fallmont.ltt, were approximately three times (tuetttei than thos ,:t. for the wet

-witm-tt-sprite, t st.ttason. Precipitation for the 12- to 18-month periodafter tteatment contained higher DDT concentrations than expectedrelaiissit to the tenon:It of rainfall foi the period and the concentrationsfount.) at 6 and 30 ntot. ,H"ts. t:tetti, 11 Di)T levels ; their seasonalvariations . ; Ty. ) thts, total ra ive iiiconetttidtationt; found in this study arcCOO. .1 II 5. il ttittttl artitt.i.t.tts and P I thoLcreported for other In.,

Table 4. - Concentratio:1 of totttal l)D7 add.'d to theforest floor in throu.z!tfalt pretsipttstionafter aerial spraying.

Months TotalAfter

Residue(ppb)

5 0.1761-12 .075

13-18 .364io_71 .066

.1033 i -36 .036

At the

cut.,i years, L)Dit conccinitttiotts 11 throughfall precipitationbad decreastat. : a ) . ptetcitably but still %veto fl y to 10 times greater than let:cisfound in satttpltts front an unttletted fittutestccl area in western OreLon( tt ri publishcti) ti tit ta t) .t),ut the total amount of D1)1 OUght dOWn over thisporiod in tin itnThrall precipitation is infinitesimal compared with that partof the intend -4 application thstt ratrebed the forest floor or wasdeposited in hi tet 'Ilms, throu ltdttitIlpttaelpittation was not a significantfactor in detettictittintt,t, tier fata rin' in in maintaining DDTcomiceiti;it: n i i he FOTCSi Hotn.

Of a total actiattl applictd ion of 1.,01 V-;) acre , 26 percentreac i ttd tlitt ro tes! !Hot in t tially, 6 patcem v. at: Itta nt..,. lat to the (most floorin lif tc11;11 it t.ssr ..i.s.,.ttat j omod, and :a li.tctiot. oft I pUlt.A;11i of the totalwas waahed from the ittit..e, canopy over 3 years (Table 5). Thus, aboutone-thild of the total ttppli, ation reached the forest floor.

In Arizott.t, le:s than 50 percent of insitteti, tics aetially applied duringthe summer depositi!d on - tinut in agricultural spraying. The

Table 5. 'Iota] DDT deposited on the ground surface (forest floor) (vie;_3 years after aerially spraying DDT at 12 ouncts per acre.

Tota l !AilSource of DDT

at Ground Surface Outicesper acre

Percent ofIota) Applied

initial deposit 3.03 25.6()

Total deposit ovci 3 years fromLitter fall .74 6.17"fitroughfall precipitation .02 .01

Total, all sources 3.84 3). 8 t);

distance from the spray aircraft to the target 1,n..a.s to becorrelated with amount of on-target chemical application (12). lircriftspraying forest lands must fly at far greater heights thenover level agricultural fields. Thus, the comparatively . hizh arc:ow-it of D1..Y1reachinla, the foicst floor is not surprisiTa. This fiiHifi2 itaffitrits tItatefficient methods of acrial spraying musl. bra developed if 1 .12 are to 1

undue loss of chemical to nontarget ateP,S.

PHORAJT:Phorate (Thimet) is a highly toxic systemic orpnophospite

used heavily in cotton production and also on SOnie

southwestern United States. This chemical eont:ols insects On C011,2,1!

up to 5 months, but residues in soil have disappeared long berf)ft,.

Climatic conditions in southwestern United Sttates, of course, ate rtt,t,tt.tIlt,..different from those in the Douglas fir regt011 of the Pacific Nor thwtast.

Phorate was broadcast on the ;of est floor at rates of 1, 10, tut.td100 pounds per acre in a stand of young Pacific silver fir at each of ttaowestern Oregon locations in May 1966 (3). Persisteit.s e of phoratc cr,id itsmetabolites (measured as phosphorothielate stiltno) wos deicrmin..2.!the end of each of the first two seasons after application. Tt-ttpurpose of this expetiment was to determitic wht-tther pht.'a oltitdprotect youn i; trees a .:rinst aphids and vdiethor residua p2o;istem:csimilar to that in warmer climates.

Mean concentrations in the forest floor after 6 months were 2.04-,0.58-, and 631-ppm ph orate and 2.78-, 26.56-, and 238-ppin metabolitefor the 1-, 10-, and 100-pound-per-acre rates, respectively. Completedegradation WaS quite rapid at the two lower rates as indicated by total

136 137

resid'des of 8./10 and ().03 perocill In chemical applied for the forest flowand iiurface 12 inches of soil combined. Al the 100-pound talc, however,0 0peicen' tic total cl: ..; : cal applied 3is still present in the forest floor

j hiti 3 tt ii, i; ,:iLttabolites. Some dowirward movement had1. hen pl a ce, ltwi less Li perc,mt of the total residue N\3:, found belowthe ll-ineh rfn 8 months, nicasorable levels of both phorate

of iis v.;ic thr foresi flooiInd soil. At the

lateill ipph, 1.10.11 poinick perflute.

Thds study L, IL cannot pletliet !be hellavi—, andporsit,:itc..., 0 folk.:si ,:;110,2,1on. from ple',..i(rusexperience undci aglicultural in this fomect studypersisted beyond (lie lirst ov;lii , wecan piribably due to a combinationof faei . ,is. Dining the suilnitin toonths,microliird activity is low beciicst ofdry in th e fores t, soil. Chemical clegriidation did take p iercelower riles, but the highest late of chemical applied was srifficiently toxicessent: . to stop the already lov: level of mlerobial activity. Bythe time the soil moistine simply increasod with fail rains, soil tempera-tures hi .d already dropped to loss titan optimum and microdial activityremained low until the following spling.

PeH 01. Ilcibicides,l'otn 16:11)1( . 1; 1 ,s, C' molly used in die Paeific Nciithwest I II contiol

tin y/tinted vegetation: 2,2,-D, amitole, 2,d,5-T, and picloram. 'nosechemicals :Ire 11 ,m;d,:! I pCiSiA l; nt. All of them are degraded hi theforest hut: lhhtIm tLLict ratcs (6).

10 RAI foiL:st 1.0;e!, 1 t. rapidly of all (figure 1).Iii laboratoiy studies, 35 days' i ncithatirm, only 6 percent icinainedof a total'application of 2A-I --) at the rate of 2 pounds per 3C1C: and only 5percent Ill Lied of a d-pound fi t acre application. The rate of 2,4-Ddegradation is slowed somewhat wheii elftn i 2,4,5-T or piclota q n is applied

but at ter 35 (Iays, total dciradafiun i, the same OS for 7,4-I)alone.

i:Ti,fty0 f; 21 incubation, only 20gees-It of a 2-pi)und-p,!Yaci p 1 ) 'aof antilrole remained in forestfloH IICH iil. PL.f:.!.tonc(... :irr,..ted when 2m) \vas

than that of 2,1-1') orbut anti 11'0 days, only 1.l peiceill of a 2-pound-per-ecie

application and I pOICCIIt of a 4-pound-1 ' ei-acie application remained inred aldei best floor matelial.

120

100

90

CO

a5 roa2-

0LU

25

1 3

0 20 O CO IC3 .(2; 10,:

1 . 1%,1E (day;;)

Figure J. -- Recovery of MI), amitrode, and picloram from iedalder forest floor material. Source: No Is 1970(a).

Picloram (trader-nail Tordon) is a relatively new of coyi--td.able potential use in controlling unwanted .1. 1 fyirsi-rilyapplied at a lower rate than 2/1-1) or 2,4,5-.1 be:combination with them. V, The.n picloram yeas applied at 0.5 pound por acrewith and without 2,44) at 2 pound., OILcre, tlicte w'asdifference in persistence. of picloram (6). After '1'60 s,than 60 percent of the initial appltairflim of piclorant rcfitTh-ied tliforest floor.

Results of these laboratory studios have been confirmed b y field.of operational spraying. A number of monitorin$ observat;ons Ii v.',:srr

Oregon and Washington have indicated that when forest 1:ni1swith herbicides during the spring growing sea.;on ineasuLilide quantities orherbicides are not present in streamwatcr during:the first fall Sti.:hrains did not introduce measurable amounts of herbieid,ts in theflowing through the small seattercd treatment units froreoperational vegetational control ineasul es. These ate tine for2,4-1), 2,4,5-T, and amity- 01,2. Even in CLCS \\lick., a faHy

of a r, ECISIR'd Ls tle;11Cd oitlI herbicides and w-hoL• the ti:.'ettnentunit is oriented for a considerable distance along the ne. ai, no

measurable amount of herbicide was found after the first fall mains (4).

Thus, unless a heavy application of chemical is mihie directly into the

stream, the major potential for stream contamination from herbicide

50

138 139

li the Itirest is limn II Ivy I 1011 or ino \ einent resullin ill ovellaudof ‘,..;tc■ and sediment silo) fly after tipplication. Stich conditions ()cmonly 1,1:left

Piclomm is sometimes applied with pheao,sy herbicides in the summerfor bred 1 ulihniA 1,i),,Vc1 Tin .: i:Ner for;!st hipAis, III 1 Is

st;,h atteatnn : after th.: IH.t \t/stet.u .a'uthet.

-N-Rintorr ('IIlCIlsy :flift,.r;1110 fal!are surricieml \ intense to cause td,;:‘,:it tatht:-.1.Wine). I I .s ra..,1111.1;1{", il111010i1 1.! 'Ill i;;by the potportion of the \s, atesahed that k treatett (5). lit i.adtconttnninmion was very lo\v 0 n ooasjinuni of 1 ppb found 0!dy oni.";sample.

C.

In aneioh . u Urupnu fü iVSt, IC:WC 1111 of the D1)1rettchitit, tio . I s, 0. rIt'll' 00r..d sin ayinz had disappeared ill the end ofthe his! 3 y( afier splayitT, t" 'date of the applied 12,Di \'a: present inthe end of 3

, •.- ! ‘tu Co.'dittl ot-dd tics of ti 1)0.1(1 ) to):ic systemis013plft. . pl.,. ale cle , ratiod quite rapidly 540.0 ap-plicatiou eilhet 1 (1' 10 poun,h,per acie. Iiowavet, at an

tt tt t (rt." p.2,H,..cAlt Of ti's' chr,:nlic:11'tilt in t1l Fort.,, -...1 flout .1 -1(1. alto) 6 months. Ai thc,

100 potind-itta-e.'k. ! nat,e, a total :s. ridtrt Of 4.50 pounds pc] acre \vas stillpreseni ntot-J11 from Co ,. stuck; un (bc, ) 10051 c 0 11 OkOI1Sate .at,aacc C. the same. chemical used ona,t,nicult w al 0.ty, M .,./arlitet

D most rapid!)'. Amitrole alsod:Trtnti.;s brit p.c0nm1, are of somewhat !only]ptasist, u,t, fits rains anel applicationof ti e.. e h tulls . , ds indieaht, ev,te, that 2,4-D, ?,4,5-T, 11)1) temitotl..residutn, not avtd1thle for tiansport to streamwater after havaig

one stenn.al..

Literature Cited- -

Abbot, I). C., Cr. 1/. Parr -roil, J. O'G. Tattoo, and J. Ihomson. 1965.

Organochlotine pesticides ill the atmottplterit, envir(nment. Nature 21,t't:

1317-13113. -

Gttcirt.i, W. I)., and W. E. Beafcl. 1967. Movem aitd pei:dstert ,.:e of 1)1)T

and litudit le i sot! column ,- SOIl Sci. Soc.:. A Pro:. 31, 6).-1,1-6z7.

Moore, D. G., E. L. Ilok,,mnIte, and P. 1 7 . Slratd. 1969.persfstonce in it fortn,t soil Abstr. in Northwt.:,t 1. 43: 40,

Loi,ar) A. 1968. Stream coataminatton by 1,0.f1tir.t.

on forest land. In: Res, Proitk Rep., W. Soc. Weed Sci., pp. 33-3.4.

LoLan A. 1969. -Herbicide- runoff fin i forest lands sprayed to

sumincr. In: Res. Pro41. Rep., W. Soc. Weed S. .p. 24-26.

Norris, I,Ofj.an A, 1970(a). DttL,,radation of lierhieldes 9 tlYr lktor.

In: Tree Growth and Forest Soils, C. T. '3(a:i.,;4st T1" :.o1 C, 13. 1)

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