• Abstract and Figures
• Public Full-text

Occurrence of Cotton Pesticides in Surface Water of the Mississippi Embayment £ Michael Thurman, Lisa R. Zimmerman, Elisabeth A. Scribner, and Richard H. Coupe Jr. This fact sheet introduces a study of the fluometuron is a cotton herbicide used The three most-used pesticides are nonpoint-source occurrence of pesticides primarily in Mississippi and in the herbicides (monosodium methylarsonate, in water of the cotton-growing areas of eastern coastal plain (fig. 2; Battaglin and trifluralin, and fluometuron). the Southern United States with special Goolsby, 1995) but is little used in other emphasis on the Mississippi Embayment cotton-growing areas. Study Area (fig. 1). This study is being conducted by the U.S. Geological Survey (USGS) The geographic usage information A major area for cotton production in Organic Geochemistry Research Group, displayed in figure 2 can be useful for the United States is the Mississippi which investigates the fate and transport designing regional water-quality surveys Embayment (figs. 1 and 4). The area of agricultural chemicals in the and for methods-development strategies consists of parts of Arkansas, Kentucky, environment. The purpose of this fact for a compound such as fluometuron. Louisiana, Mississippi, Missouri, and sheet is to give an overview of the cotton- Another method to visualize cotton Tennessee. Rainfall amounts of as much growing areas of the United States, to pesticide usage in the United States is the as 60 inches per year and relatively flat, provide usage data for cotton pesticides bar graph shown in figure 3. The com­ only slightly permeable soils in the United States, to present pounds shown account for nearly all of characterized by large runoff volumes and information on the types of pesticide the pesticides used in cotton-growing low relief are typical of this area. Major compounds and concentrations that have areas (Gianessi and Anderson, 1995). pesticides used in the area include been found thus far in the Mississippi Embayment, and to discuss current areas of cotton pesticide research. Introduction Contamination of water in the Midcontinental United States from pesticide application to row crops (corn and soybeans) has been a major water- quality issue during the past decade. Perhaps equally important to water quality in the Southern United States is the application of pesticides to cotton, which receives three to five times greater application of pesticides per acre than does corn or soybeans. In spite of the greater use of pesticides, few regional water-quality studies have addressed pesticide occurrence in water of the Southern United States. Cotton-growing areas of the United States encompassing the States (fig. 1) extend from the East Coast Mississippi Embayment (The Carolinas) to the Mississippi Embayment. the Texas High Plains, and EXPLANATION the arid deserts of the Southwest Estimated harvested (Arizona and California). These areas of cotton, in acres the country have different climate, I I No data or 0 precipitation, and soil types, which result I 1 - 2,500 in different weed and insect pressures, as 2,501 -10.000 well as different runoff potentials; therefore, pesticide-usage, runoff, and 10,001 - 30,000 leaching patterns are often different. 30,001 - 70,000 Because of these considerations, the 0 50 100 MILES More than 70.000 types and amounts of pesticides applied 0 50 100 KILOMETERS may vary considerably throughout the Figure 1. Estimated harvested cotton in the United States, 1987 (data from Battaglin and Goolsby, 1995). cotton-growing areas. For example, U.S. Department of the Interior USGS Fact Sheet FS-022-98 U.S. Geological Survey May 1998 in the aquatic environment are being used. Enzyme-linked immunosorbent assay (ELISA) has been developed for fluometuron (Strategic Diagnostics, Inc., Newark, Delaware). This immunoassay is portable, provides rapid results, and is less expensive than conventional methods. Initial analyses have shown very good correlation between GC/MS and ELISA. Three general factors are important in defining transport, fate, and toxicity of pesticides in the aquatic environment (fig. 5). Pesticide usage, such as EXPLANATION illustrated in figures 2 and 3, provides Fluometuron use, in pounds basic source information. Chemical of active ingredient structure affects the physical properties I | No data or 0 13,501-10,000 and, thus, the persistence and mobility of I 11-1.000 110,001 - 50,000 the pesticides. Site hydrology determines 11,001 - 3,500 I More than 50,000 runoff and leaching potentials. Evaluation Figure 2. Fluometuron use in cotton-growing areas of the United States, 1987 (data from Battaglin and of all factors will enable improved Goolsby, 1995). understanding of the processes of nonpoint-source contamination and of the occurrence of cotton pesticides in surface and ground water. " to 5,000,000 03 C Occurrence of Cotton Pesticides =6 g Herbicide 5, £ 4,000,000 in Surface Water Insecticide OJ >* | "1 3,000,000 i : The major herbicides and their CD C metabolites that have been detected in H- C _ O CD surface water of the Mississippi ~ -D 2,000,000 j 1 ] 3.® i - Embayment are shown in figure 6. The ° a. < & 1,000,000 most-detected compound was fluometuron with a mean concentration ^ of 2. 1 |ig/L, a median of 0.40 |ig/L, and a o i , i .i,!. ; ,:«.ili.l.!.ll.111lMi.fi p<5 CCCOJCWJDCCCJD A CD CD CD c tn en £ 7; -5. "> "5. ^ = 2 =5 2°.E = £ S 8 £ .2 5 §« S tS £££ §£|-o>^ i: c^ t: CU ^'^;?OQO O c (-^r^frc5 CD _ :3 «E mO^fc-o ^ ^ "> 0) t s» QE--OJ <N Pesticide Figure 3. Cotton pesticide usage in the United States, 1990-93 (data from Gianessi and Anderson, 1995). monosodium methylarsonate, Water samples were extracted and fluometuron, cyanazine, pendimethalin, analyzed by gas chromatography/mass methyl parathion, and trifluralin. spectrometry (GC/MS) for the detection and quantitation of the major cotton Methods of Study pesticides. The method consists of using solid-phase extraction (SPE) for the Surface-water samples were collected isolation of the compounds followed by at 64 sites in the Mississippi Embayment elution with ethyl acetate (an organic from January-December 1996 in solvent) and analysis by gas conjunction with the LJSGS National chromatography with identification by Water-Quality Assessment (NAWQA) mass spectrometry using selected ion Program. The locations of the sampling detection (Thurman and others, 1990). - - Boundary of the Mississippi sites are shown in figure 4. Fixed sites The detection limit was 0.05 |ig/L Embayment study unit of the National Water-Quality were sampled weekly for 1 year, and (micrograms per liter) for all herbicides Assessment Program reconnaissance sites were sampled one and 0.01 ^g/L for all insecticides. Fixed sampling site time. Samples were filtered through glass- lissance sampling fiber filters (1.0 micron) and stored on ice In addition to the standard approach of until analyzed at the USGS laboratory in GC/MS for chemical analyses, other Figure 4. Location of surface-water sampling sites in Lawrence, Kansas. methods for the evaluation of pesticides the Mississippi Embayment. organophosphate insecticide that is used detected most frequently (3 percent) and Site extensively (nearly 0.7 million pounds in the highest concentrations. This result hydrology Pesticide annually in the cotton-growing areas, see is consistent with the fact that endosulfan usage fig. 3). Methyl parathion was detected is the only organochlorine that is still Fate, next most frequently, with 18 percent used legally in cotton-growing areas. transport, detections. It is the most-used insecticide Organochlorine insecticides, especially and toxicity in the cotton-growing areas, with more DDT, were used intensively on cotton than 3.3 million pounds applied annually during past years; therefore, more (fig. 3). However, because it is a volatile detailed monitoring by the USGS is Chemical insecticide, it is detected less frequently underway for DDT and its metabolites structure" and at lower concentrations in surface using passive sampling methods, such as Figure 5. Critical factors affecting the fate, transport, water than dicrotophos, which is much semipermeable membrane devices and toxicity of pesticides in the environment. less volatile. The third most-detected (SPMDs). Work with SPMDs shows that compound was profenofos at 12 percent DDT and other organochlorine maximum of 50 (jg/L (fig. 6). The detections. This organophosphate insecticides are present in surface water demethyl metabolites, demethylfluo- insecticide is used nearly three times as at detectable levels (Bastian and others, meturon and demethylnorflurazon, were much as dicrotophos, yet it is found in 1997). also commonly detected. lower concentrations and less frequently. Apparently the shorter half-life of Current Research In general, cotton pesticides are profenofos (about 7 days versus 10 to soluble in water, from 0.3 to 1,000 mg/L 15 days for dicrotophos) permits it to be Additional research by the USGS in (milligrams per liter). Experience from more rapidly decomposed in soil, and as the cotton-growing areas includes studies in the corn- and soybean-growing a result, the parent compound occurs less development of a bacterial-growth assay areas of the United States indicates that at frequently in surface water. using the luminescent organism Vibrio a water solubility greater than 5 mg/L Of the organochlorine insecticides that fischeri. Results from this analytical compounds are readily carried by surface were detected (fig. 8), endosulfan was method are being compared with runoff and occur in surface water. Cyanazine, fluometuron, and norflurazon have water solubilites greater than Number of samples = 330 Percent detections x /I ; 5 mg/L. On the other hand, pesticides <, less than 90th percentikT ; such as pendimethalin and trifluralin Mean 1 1 j (fig. 3) have a solubility less than 1 mg/L : and generally are not detected in surface runoff in the Mississippi Embayment.

Load more

  4

Copy Link