Agrochemical Fate and Movement - ACS Publications - American

Chapter 15

Pesticides in Ambient Air and Precipitation in Rural, Urban, and Isolated Areas of Eastern Iowa 1

Downloaded by STANFORD UNIV GREEN LIBR on September 20, 2012 | http://pubs.acs.org Publication Date: April 3, 2000 | doi: 10.1021/bk-2000-0751.ch015

M. E. Hochstedler, D. Larabee-Zierath, and G. R. Hallberg

University of Iowa Hygienic Laboratory, Iowa City, IA 52242

Atmospheric transport and deposition of pesticides are significant issues in better understanding human and environmental exposure. Pesticide concentrations in air and precipitation were measured over a one-year-period at four sites in Iowa chosen to characterize rural, urban and regional effects. Twenty-eight pesticides including twenty-one herbicides and seven insecticides were detected in precipitation during the sampling period, October 1996 through September 1997. Pesticide concentrations were greatest during the planting-growing season, April through August. Peak concentrations reached 0.96 ug/L for acetochlor, 1.1 ug/L for 2,4-D, and 3.5 ug/L for atrazine, all commonly used herbicides in Iowa. Concentrations were generally higher at the farm site but were present at all sites indicating distant transport. Measurable air concentrations were occasionally seen, but most were below detection limit for the volume of air sampled.

Iowa is noted for its extensive row-crop agriculture; 94% of the state's area is farmland. Most years over two-thirds of the state's land receives pesticide applications. It is estimated that Iowa applies more herbicide active ingredients than any other state in the USA (/). Preliminary studies of pesticides in precipitation in Iowa suggest that losses to the atmosphere may account for greater environmental losses than those measured in runoff or leached into groundwater. These studies indicated concentrations in rainfall near farm fields ranged as high as 40 ug/L for atrazine. Methyl parathion, malathion, and diazinon were detected in rainfall in Iowa City, but not in farm/rural samples, suggesting an urban input. These compounds are commonly used for lawn and garden insect control (1,2). Prior observations suggest that "scavenging" of pesticides, the incorporation of dissolved gases and particulates Current address: The Cadmus Group, Inc., Watham, MA 02154

© 2000 American Chemical Society

In Agrochemical Fate and Movement; Steinheimer, T., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2000.

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into precipitation, is responsible for their occurrence (1,3,4,5,6). While high concentrations have been observed in rainfall, air concentrations may be even greater, a consequence of incomplete scavenging. The regional occurrence of pesticide residues in precipitation would suggest that their occurrence in air is likely an important route of exposure to the general public, as well as to farmers. Pesticides in ambient air, dust and precipitation do contribute to inhalation and dermal exposures. To non-applicators, such as the general public, the data suggest that inhalation, as well as dermal contact, are routes of routine low-concentration exposure, similar to drinking water in parts of Iowa. Both air and precipitation are important sources of pesticide deposition in non-target areas. Our study sought to enhance the understanding of the route of human and environmental exposure to pesticides by measuring concentrations in air and precipitation over a one-year-period at four site locations in Iowa. We evaluated the significance of location for sample collection and explored the difference between wet and dry precipitation. Samples were analyzed for a large number of pesticides to extend the database on pesticide exposure. Materials and Methods Four site locations within Johnson County, Iowa, were chosen for our study. Figure 1 shows Johnson County in relationship to the rest of Iowa and the sampling site locations within the county. The Farm collection site, located three miles west of Iowa City, was used to characterize local transport effects. This site is surrounded by 260 acres of farmland. The Urban collection site was chosen to measure urban effects and distant transport from agriculture. It is located in an older residential neighborhood in central Iowa City. The Macbride collection site was chosen as a control in an attempt to find a site isolated from localized effects. This site is located ten miles outside of Iowa City in a recreational park which is undeveloped for agricultural or residential use. The Oakdale collection site was chosen for continued monitoring after the initial study. This site has characteristics common to all three and is located at the University of Iowa Hygienic Laboratory. It is near cropland, urban areas, uncultivated fields (pasture), and wooded park areas. A total of 222 precipitation samples, 124 dry deposition samples, and 288 air samples were collected and analyzed during the one year sampling period, October 1996 - September 1997. All samples were analyzed at the University of Iowa Hygienic Laboratory. Seventy-eight compounds were included in the protocols (See Table I). This list is based on those analytes routinely determined by gas chromatography in the Pesticide Residue Section of the University Hygienic Laboratory. Air Samples. Air samples were collected and measured using an adaptation of U.S. EPA Method IP-8 (7). Approximately 1.5 m of air was sampled over a 24-hour-period using a programmable, battery-operated pump operating at 3 L/min. The pump cycled 3



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Figure 1. Maps showing sampling sites in Johnson County, Iowa.


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Table I. Pesticides and related compounds included in the study. Number of detections in 634 samples from all matrices are given in parenthesis. Nitrogen Containing Compounds EPTC Butylate Propachlor Atrazine(59) Trifluralin(l) Metribuzin Cyanazine(16) Alachlor(2) Metolachlor(29) Pendimethalin(ll) Prometon Propazine Triallate Acetochlor(20) Bromacil Butachlor Simazine Carbaryl Carbofuran(l)

Organophosphate Insecticides Isofenphos Phorate Dimethoate Dyfonate Disulfoton Methyl parathion Parathion Ethoprophos Terbufos Diazinon Malathion Chlorpyrifos(3) Dichlorvos Metabolites Desethyl atrazine(ll) Desisopropyl atrazine(5)

Chlorinated Insecticides and Related Heptachlor(6) alpha-BHC beta-BHC Heptachlor epoxide Lindane(4) Endrin delta-BHC Endrin aldehyde(7) Aldrin Endrin ketone(l) Dieldrin(3) Endosulfanl(l) Endosulfan II DDT(3) DDD Endosulfan sulfate DDE(7) Methoxychlor

Chlorinated Herbicides and Related Compounds 2,4-D(14) Dicamba(6) Silvex(4) Bentazon(4) Picloram(4) Dichlorprop(15) Pentachlorophenol( 16) 2A5-T(2) Chloramben(2) Acifluorfen(l) Dinoseb Bromoxynil(2) 2,4-DB(l) Dacthal MCPP MCPA Triclopyr(l) Compounds Chlordane Toxaphene Aroclor 1016 Aroclor 1221 Aroclor 1232 Aroclor 1242 Aroclor 1248 Aroclor 1254 Aroclor 1260


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on for one minute and off for two, giving rise to a 1.5 m air sample per 24 hrs. Air samples were passed through a collection device consisting of an open glass tube, containing a specially cleaned polyurethane foam (PUF) plug. Airborne particulate matter was retained on a glass fiber pre-filter. PUF plugs were extracted in a Soxhlet extractor for 16 hours with 5% diethyl ether in n-hexane and the extracts concentrated to 3 mL in a Kuderna-Danish concentrator. They were then analyzed by gas chromatography using either electron capture or nitrogen-phosphorus detection. Because the extracts were relativelyfreeof artifacts, protocols for drinking water methods were used. The glass pre-filters were analyzed in the same manner to assess particulate loading. Precipitation and Dry Deposition Samples. Precipitation samples were collected using automated, wet/dry samplers of the design used for the National Atmospheric Precipitation Assessment Program (Aerochem Metrics Model 301, Bushnell, FL). This collector consisted of two buckets, each containing a large glass beaker. An automated cover was connected to a motor and sensor activated by water. Whenever the sensor detected rainwater, the motor moved the cover from one bucket to the other. Thus wet and dry precipitation were collected sequentially. The rainwater in the wet bucket remained covered to minimize evaporation loss. Samples were also collected in galvanized steel basins (hog pans) to provide adequate sample size during small rainfall events. These basins collected both wet and dry deposition, also known as bulk precipitation. The wet/dry collectors generally operated well through the winter months during snow events. Some difficulty was encountered when the collected snow melted, then refroze, breaking the container resulting in complete loss. Protocols defined in EPA Methods 507, 508 and 515.1 (8) were selected because low detection limits were a priority and samples were generally free of interferences. The precipitation samples were transferred to 1-L glass jars with Teflon lined polypropylene lids specifically cleaned for pesticide analysis. Precipitation collectors were rinsed with distilled water after sample removal and returned to the collector. Samples were refrigerated and extracted by solvent extraction within a 7-day holding period after collection. After concentration and exchange into n-hexane, the extracts were analyzed by gas chromatography with either electron capture or with nitrogen-phosphorus detectors. Samples were collected from the dry bucket beakers by rinsing each with 200 mL of acetone in the field. The acetone was transferred to 1-L jars for transport to the laboratory. The acetone extract was concentrated and exchanged into n-hexane for analysis by gas chromatography as above. Method detection limits (MDL) for all compounds generally ranged between 0.01-0.2 ug/L for rain and snow, depending on the analyte and the volume of sample collected. For air the range of detection limits for all compounds was 0.1-0.2 ug/m . Dry sampler detection limits were in the range of 0.05-0.2 ug/sample, also dependent on the analyte. Compounds not classified as herbicides or insecticides were included 3


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in the analytical protocol since they are target compounds in the methods used for this study. Polychlorinated biphenyPs (PCB's) have traditionally been determined by chlorinated hydrocarbon insecticide methods and are included in EPA Method 508. Pentachlorophenol, 4-nitrophenol and 3,5-dichlorobenzoic acid are included in EPA Method 515.1. QA/QC. The University Hygienic Laboratory follows very strict quality assurance and quality control (QA/QC) guidelines to maintain highest degrees of precision and accuracy. These procedures include, but are not limited to: daily instrument calibration verification, interference checks (blanks), standards verification, and assessment of extraction efficiencies as well as PUF plug capture efficiencies. Duplicate air samples were taken every other week at one site, rotating the four site locations. Not enough results from air samples were positive to give meaningful statistics for sample duplicates. One reagent blank was prepared for each set of air samples, to test for false positive results. 4-Nitrophenol was often tentatively identified by dual-column gas chromatography; however this result could not be confirmed by mass spectrometry at the concentrations observed. A field exposed spike, prepared by spiking 100 uL of known concentrations of analytes in acetone to the inlet side of the polyurethane foam plug, was taken monthly at each site for air sampling. These spikes generally averaged near 100% for chlorinated hydrocarbon insecticides with standard deviations between 8-14%. Field exposed spikes for acid herbicides gave lower recoveries with 2,4-D averaging 66 % and silvex averaging 80%. Recoveries of nitrogen containing herbicides were generally very good, typically averaging 100%, with standard deviations of 10%. Some pesticides were not recovered from field exposed spikes. Comparisons with spikes prepared in the laboratory suggests that butylate volatilizes from the collector, while trifluralin is poorly extracted from the PUF plug. Laboratory fortified blanks were prepared with each set of wet precipitation and dry deposition samples. Recoveries fell in the ranges specified by the EPA drinking water methods 507, 508, or 515.1. Blanks prepared with each set of samples showed no contamination. Results Figure 2 shows rainfall data from the Iowa Institute of Hydraulic Research, University of Iowa, during the sampling period with corresponding long-term averages. Notably, May was above normal and June and July were below normal. Pesticides were detected in all sample types: air, wet precipitation, dry deposition and bulk precipitation, at all four locations during the one year study. May and June were months of the highest frequency of pesticide detections. Thirty-four of the 78 compounds in the screening protocol were detected. Of the total of 634 samples collected, the most frequently detected pesticides and related compounds were atrazine (8.7%), metolachlor (4.6%), acetochlor (3.1%), cyanazine (2.5%), pentachlorophenol


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(2.5%), dichlorprop (2.4%), and 2,4-D (2.2%). These pesticides were found at all four sampling site locations. Figure 3 shows a comparison of atrazine in bulk precipitation and wet precipitation. The distinctions between the two do not seem to be significant. Precipitation. Atrazine occurrence in rainwater at each of the four sites is shown in Figure 4. As the most frequently detected pesticide, it was quantified at a maximum concentration of 3.5 ug/L at the Farm site in bulk precipitation. This is not surprising, atrazine is widely used in Iowa, and is the most frequently detected herbicide in most other water quality studies within the state (/). There were 8 million lb. of atrazine used on corn in Iowa in 1996 (P). Detected only during the spring and summer months of April through August, atrazine occurrence shows a definite seasonal trend. It is noteworthy that atrazine was detected more frequently at the Urban site than any of the others, including the Farm site. Figure 5 shows data for metolachlor, the second most frequently detected pesticide in this study. It is also widely used in Iowa. Its occurrence shows the same trend as atrazine, being detected only during the spring and summer months and at all four collection site. In contrast to the atrazine case, the concentrations of metolachlor were at or near the limit of detection. Consequently, the sensitivity of this measurement was very sample volume dependent. Figure 4 also illustrates the dependence of the determination upon sample volume. Some very low level detections may have been missed using this protocol. Acetochlor occurrence in rainwater at each of the four sites is shown in Figure 6. As the third most frequently detected pesticide, it was quantified at a maximum concentration of 1.1 ug/L at the Farm and Macbride sites. While the Macbride site was chosen to represent a non-agricultural source term, it is interesting to note that the same concentration was detected at the Macbride site as at the Farm site, where the pesticide was likely applied. Unlike atrazine and metolachlor, acetochlor does not have a long use-history on Iowa row crops. Figure 7 shows the levels of 2,4-D detected in rainwater at all four sites. It follows the same trends as atrazine, metolachlor, and acetochlor. It is noteworthy to point out that 2,4-D is the only herbicide of these 4 detected in rainwater which is currently registered for both agricultural and non-agricultural (commercial and residential) use. Table II shows chlorinated insecticides in all types of precipitation for all four sites. These insecticides, most of which are no longer registered for agricultural usage, were present in ultratrace amounts, and detected throughout the year, showing no seasonal trends. Air Samples. Table III shows results for pesticides in air samples collected using the PUF plug. Most detections were below the quantitation limit of 0.5 ug/sample. At the farm site 2,4-D was detected in air at a maximum concentration of 0.34 ug/sample. Both pentachlorophenol and endrin aldehyde were detected more frequently than any other pesticides and they were detected at all four sampling sites, and more frequently than any other pesticides. Other pesticides found in air include atrazine, cyanazine, dicamba and lindane. These were found in air samples collected in the fall (October and November) and also in the spring/summer (May through September). The


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Table II. Rain and bulk precipitation data for the chlorinated insecticides detected from each site for each sample. The value is the concentration found in each rainfall or snowfall event. Farm Oakdale Macbride Urban Month Analyte ug/L Analyte ug/L Analyte ug/L Analyte ug/L Oct-96 Nov-96 Dec-96 Heptachlor 0.0073 Jan-97 Heptachlor 0.016 Dieldrin 0.0093 0.016 Chlordane 0.037 Endosulfan I 0.0081 0.021 0.011 0.038 Heptachlor 0.035 Lindane 0.010 Chlordane 0.038 Lindane 0.0099 0.018 Feb-97 Mar-97 Apr-97 EK 0.0094 May-97 Jun-97 Dieldrin 0.0085 Dieldrin 0.0036 Jul-97 Aug-97 Sep-97 EK is endrin ketone 1



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Table III. Air sampler data for all analytes from each site. The value is the concentration in the air at each sampling. Farm Oakdale Macbride Urban Month Analyte ug/m Analyte ug/m Analyte ug/m Analyte ug/m Oct-96 PCP 0.072 0.07 PCP 0.032 Dicamba 0.018 PCP' 0.058 PCP 0.1 0.076 Nov-96 PCP 0.025 Cyanazine 0.11 Dec-96 Jan-97 Feb-97 Mar-97 EA 0.0097 Apr-97 May-97 EA 0.021 EA 0.031 Jun-97 2,4-D 0.34 Atrazine 0.14 Jui-97 Lindane 2,4-D 0.22 0.47 EA 0.0089 Aug-97 EA 0.0093 Atrazine 0.014 Sep-97 3

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relatively high concentration of lindane determined at the Farm site in July is fully consistent with the volatility of this insecticide, as inferred from its vapor pressure and its Henry's Law constant. Dry Samples. Table IV summarizes the dry sampler data. Generally, frequency of detection for all pesticides is less than observed with the wet sampler. However, analysis of the dry samples reveals that more different chemical classes of pesticides are deposited from the atmosphere in association with particulate matter than those observed in wet precipitation. Consequently, fundamentally different physicochemical processes are controlling deposition in the dry phase and the wet phase. The fewest detections were observed at the Macbride site. Approximately the same number of detections were observed for the Oakdale and the Farm sites. More pesticides were detected at the urban site than at any of the others. These detects represent a combination of herbicides and insecticides used in row crops together with several insecticides which are either banned in the U.S. or sold specifically for nonagricultural uses. These include DDT, along with its primary environmental degradate, DDE. Conclusions Seasonal variations in frequency of occurrence of pesticides in precipitation is observed for many currently used pesticides. These would include: triazine herbicides, chloroacetanilide herbicides, chlorophenoxy acid herbicides, organochlorine and organophosphate insecticides. These results are consistent with those reported by Hatfield, et al. (10) in which nearly 90% of the detections of atrazine, alachlor and metolachlor occurred between mid-April and early July. In addition, several pesticides which are banned from commerce have also been detected. These chemicals, no longer in use, do not show a seasonal trend and appear throughout the year in ultratrace concentrations. This would suggest that the major source of contamination is from recently applied pesticides. Since detections occurred at the Macbride site, a recreational area removed from cropland areas, as well as at the Urban site, these studies reaffirm the hypothesis that transport over long distances does occur. More detections occurred at the Urban site than any of the other sites. While it is likely that urban use may contribute somewhat to the frequency of detections, the most frequently detected compounds must originate from agricultural landscapes. Systematic differences in wet precipitation and bulk precipitation were not evident from the data collected, The number of detections in air was too few to make meaningful conclusions. Efforts must be made to lower detection limits by modifying collection techniques to permit larger sample volume.



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Table IV. Detections from the dry deposition sampler data from each site. The value is the total mass recovered from the collector. Farm Urban Month Analyte Analyte Oct-96 Chlorpyrifos Nov-96 Picloram Dec-96 DDE Jan-97 Feb-97 Mar-97 Apr-97 May-97 Picloram 0.27 PCP 0.5 Atrazine 0.11 Silvex 0.1 Atrazine 0.25 0.14 Cyanazine 0.04 Cyanazine Metolachlor 0.25 Pendimethalin 0.2 Jun-97 Atrazine 0.1 Chlorpyrifos Jul-97 Aug-97 PCP Sep-97 DDE DDT Atrazine Chlorpyrifos PCP is pentachlorophenol EA is endrin aldehyde 1

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Acknowledgment The authors wish to thank Ed Engroff, Leonard Marine, Carlos Rodriguez, Scott Hinz, and Mark Hurt for field sampling and field record analysis. Our thanks to Mary Jo Kline, Greg Jacobs, Dick Sweeting, Peter Ma, Rick Derrig, Bernie Kirby, Ryan Carter, and Karla Benninghoven for sample extraction. Thanks to Paul Beney, Pam Mollenhauer, Wayne Patton, and Vicki Reedy for sample analysis. Thank you to Matt Nonnenmann for assisting with data reduction. Our thanks also to Dr. Mary J.R. Gilchrist, Director of the University Hygienic Laboratory, for the support and time necessary to complete this work. A special thanks to the Center for Health Effects of Environmental Contamination (CHEEC) for their part in sponsoring the project. Literature Cited 1. Nations, B.K.; Hallberg, G.R. J. Environ. Qual. 1992, 21, 486-492. 2. Nations, B.K.; Hallberg, G.R.; Libra, R.D.; Kanwar, R.S. In Agricultural Research to Protect Water Quality; Soil and Water Conservation Society: Ankeny, IA, 1993, pp 142-145. 3. Ligocki, M.P.; Leuenberger, C.; Pankow, J.F. Atmos. Environ. 1985, 19, 16091617. 4. Atlas, E.: Giam, C.S. Science 1981, 211, 163-165, 5. Glotfelty, D.E.; Williams, G.H.; Freeman, H.P; Leech, M.M. In Long Range Transport of Pesticides; Kurtz, D.L.,ed.; Lewis Publishers: Chelsea, MI, 1990; pp 199-221. 6. Pesticides in the Atmosphere: Distribution, Trends, and Governing Factors, Majewski, M.S.; Capel, P.D., ed.; Ann Arbor Press, Inc.: Chelsea, MI, 1995; 214 pp. 7. EPA Method IP-8: Organochlorine and Other Pesticides, EPA Compendium of Methods for the Determination of Air Pollutants in Indoor Air. Draft published March 1989. 8. Methods for the Determination of Organic Compounds in Drinking Water EPA/600/4-88/-039 - December 1988 (Revised July 1991). 9. Hallberg, G.R. Derived from National Agricultural Statistical Service and Iowa State University Extension Service Surveys of Agrichemical Use and Practices. And updated from Mayerfeld, D.B., Hallberg, G.R., Miller, G.A., Wintersteen, W.K., Hartzler, R.G., Brown, S.S., Duffy, M.D., and DeWitt, J.R. Pest Management in Iowa: Planning for the Future; IFM 17, Iowa State University Extension, Ames, IA, 1996. 10. Hatfield, J.L.; Wesley, C.K.; Prueger, J.H.; Pfeiffer, R.L. J. Environ. Qual. 1996, 25, 259-264.


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