Progress 10/01/08 to 09/30/13
Outputs
OUTPUTS: In 2008 and 2009 water samples were collected and analyzed for pesticides from four rivers in rice growing country every two weeks during the summer. From 2010 to 2012 samples were collected from the four sites on the Cache river and one site each on six tributaries. Sediment samples were also collected in 2010 and 2011. Water analysis in 2010 and 2011 was also done for pH, temperature, specific conductivity, turbidity, and total nitrogen. The aqueous stability of 5-ketoclomazone, a degradate of clomazone that is purported to be the biologically active form of the compound, was measured. The herbicidal activity of the hydrolysis product, 5-ketoclomazone acid, was measured against clomazone-susceptible barnyardgrass and other weeds and crops. Potential for using the 5-ketoclomazone acid as a pre-emergence or post-emergence herbicide was evaluated. The influence of nitrogen and presence of plants on phyto-remediation of pyrene in soil was measured in the greenhouse. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Rice pesticides were found more frequently in river water early in the spring and early summer when the pesticides were usually applied. Quinclorac and clomazone were the most frequently detected compounds and usually at the highest concentrations. The highest concentration for any compound was 123.2 ng/mL for clomazone at a tributary site on June 3, 2010. Stream flow on the main Cache river was measured at USGS gauging stations and was used to estimate the pesticide load (concentration x volume). Specific conductance was at times higher than normal, but not high enough to affect paddy rice. Turbidity, pH, temperature, and dissolved oxygen were not found in a range that would cause environmental problems. Rarely, approximately once per year or less, would a pesticide be at a concentration that might cause some kind of effect, such as affecting the microscopic structure of algae or marginally reducing the population of an aquatic plant. In each case it was a one-time occurrence, not a chronic condition. Two years worth of data showed that sediment was not acting as a sink for sorption of these compounds where they could be slowly released over time. 5-Ketoclomazone in water was shown to degrade to 5-ketoclomazone acid with a half-life of 30.5 min. The 5-ketoclomazone acid had herbicidal activity toward clomazone resistant barnyardgrass when applied foliarly or in nutrient solution. The activity in soil was very limited in time, making it unlikely to be used as a pre-emergence herbicide. Although it has foliar activity against barnyardgrass and other weeds, it also had activity toward major crops, making it unlikely to be used as a post-emergence herbicide.and it has activity against crops which makes it unlikely to be used as a post emergence herbicide. Pyrene, as a representative of polycyclic aromatic hydrocarbons, represents what could be present in soil as a result of a fuel or oil spill. The correct amount of inorganic nitrogen along with bermudagrass can enhance soil degradation as part of a soil remediation procedure.Degradation of pyrene in soil was affected by both the presence of bermudagrass and inorganic nitrogen. In the absence of plants, high levels of inorganic nitrogen decreased biodegradation. Addition of bermudagrass plants stimulated both pyrene degradation and the number of pyrene degrading microbes.
Publications
- O.A. Thompson, D.C. Wolf, J.D. Mattice, and G.J.Thoma. 2008. Influence of Nitrogen Addition and Plant Root Parameters on Phytoremediation of Pyrene-contaminated Soil. Water Air Soil Pollut. 189:37-47. J.D. Mattice, B.W. Skulman, and R.J. Norman. Environmental Implications of Pesticides in Rice Production. B.R. Wells Rice Research Studies. 2008. R.J. Norman, J.-F. Meullenet and K.A.K. Moldenhauer, editors. 165-174. J.D. Mattice, B.W Skulman, and R.J Norman. Environmental implications of pesticides in rice production. B.R. Wells Rice Research Studies. 2009. R.J. Norman, J.-F. Meullenet and K.A.K. Moldenhauer, editors. 123-132. J.D. Mattice, B.W Skulman, and R.J Norman, and E.E. Gbur Jr. Analysis of river water for rice pesticides in eastern Arkansas from 2002 to 2008. Journal of Soil and Water Conservation. 2010. 65(2):130-140. J.D. Mattice, A. Smartt, S. Teubl, T. Scott, and R.J. Norman. Environmental Implications of Pesticides in Rice Production. Research Series 591, B.R. Wells Rice Research Studies. 2010, R.J. Norman and K.A.K. Moldenhauer, editors. 141-153. Environmental Implications of Pesticides in Rice Production. J.D. Mattice, A. Smartt, T. Scott, and R.J. Norman, submitted to B.R. Wells Rice Research Studies for 2011.
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Water and sediment samples from four sites on the Cache River and from six tributaries were collected weekly from May 18 through July 6. Water was analyzed for clomazone, quinclorac, imazethapyr, propanil, four pesticides used in rice production, and 3,4-dichloroaniline, a degradation product of propanil. Water pH, specific conductance, temperature, dissolved oxygen and total nitrogen was also measured. Sediment was analyzed for the four pesticides and the degradation product. Results have been submitted for publication in the B.R. Wells Rice Research Studies. PARTICIPANTS: John Mattice. PI. Responsible for sample analysis and interpretation of results. Alden Smartt. Undergraduate student. Responsible for collecting samples, taking field measurements, extracting samples. Kristen Karnes. Undergraduate student. Responsible for collecting samples, taking field measurements, extracting samples. Undergraduates received training and experience in collecting samples, maintaining a lab notebook, and extracting samples. TARGET AUDIENCES: The target audience is rice producers in Arkansas. The unusual flooding in the spring provided an opportunity to see how reduced acreage planted along with flooding would affect the results compared to previous years results. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
There was extensive flooding in the sampling area during the spring which resulted in reduced acres planted and reduced pesticide use. This may account for reduced number of detections and reduced concentrations found in water. Compounds that may have been detected were washed off the fields early and could not be detected later. Fields that could not be planted had no pesticides applied at all. Sampling site RM was inaccessible for the first two sampling times, because the access road was under water. The gaging station for stream flow at Cotton Plant was washed out and data were unavailable until June 16. Although detection frequency was lower in 2011 than in 2010, the distribution between main channel and tributaries was almost exactly the same each year. In 2010 the frequency for the main channel was 68.1 percent, and for the tributaries it was 66.3 percent. In 2011 for the main channel it was 47.3 percent and for the tributaries it was 48.8 percent. There was more variability in pesticide concentrations in the tributaries than in the main river, and in 2011 the ten highest concentrations were found in tributaries. The highest concentration found was 32.1 ng/mL for quinclorac (Facet) at tributary site RA on June 7, and the second highest was 26.9 ng/mL for quinclorac at the same site on June 14. The highest concentration found in the main Cache was 10.1 ng/mL for clomazone on June 28 at site QM. Clomazone and quinclorac were the most frequently found pesticides. Clomazone was found more frequently than quinclorac (88 percent of possible detections vs 58 percent), but when found, quinclorac mean concentrations were up to 2.2 times higher than clomazone concentrations. Specific conductance in water in 2011 was lower than in 2010, and as in 2010 should not be high enough to affect yields of paddy rice. The historic 25th percentile for total estimated nitrogen concentration is 0.82 microg/mL (calculated) or 0.71 microg/mL (reported) meaning historic concentrations exceeded these values 75 percent of the time. Our values for 2011 exceeded the calculated value 78.2 percent of the time and the reported value 84.6 percent of the time. In 2011 no sediment samples contained detectable concentrations of the pesticides or degradation product. Sediment does not appear to be a sink for sorption of these pesticides which could then be released later.
Publications
- Environmental Implications of Pesticides in Rice Production. J.D. Mattice, A. Smartt, S. Teubl, T. Scott, and R.J. Norman. Research Series 591, B.R. Wells Rice Research Studies 2010, R.J. Norman and K.A.K. Moldenhauer, editors. Pages 141-153.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Water and sediment samples from four sites on the Cache River and from six tributaries were collected weekly from May 18 through July 8. Water was analyzed for clomazone, quinclorac, imazethapyr, propanil, four pesticides used in rice production, and 3,4-dichloroaniline, a degradation product of propanil. Water pH, specific conductance, temperature, dissolved oxygen and total nitrogen was also measured. Sediment was analyzed for the four pesticides and the degradation product. Results have been submitted for publication in the B.R. Wells Rice Research Studies. PARTICIPANTS: Alden Smartt and Silvia Teubl: Hourly undergraduate students in our department who collected samples and prepared samples for instrumental analysis. They received training on record keeping, fortifying QC samples,and doing some data processing of chromatographic results. TARGET AUDIENCES: Targets are scientists dealing with the environment, primarily water quality in agricultural areas. They will most likely see the written reports or journal article. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
There was more variability in pesticide concentrations in the tributaries than in the main river, and the highest concentrations were also found in tributaries. The highest concentration found was 123.2 ng/mL for clomazone (Command) at tributary site QC on June 3, and the second highest was 56.3 ng/mL for 3,4-dichloroaniline at the same site on May 25. The highest concentration found in the main Cache was 10.6 ng/mL for quinclorac on June 9 at site QM. Stream flow on the Cache varied more than concentration, therefore, low flow in the summer had little effect on concentration but substantially decreased the load (concentration times volume). Clomazone and quinclorac (Facet) were the most frequently found pesticides. Clomazone was found slightly more frequently than quinclorac (94% of possible detections vs 86%), but quinclorac was found at higher concentrations (mean of 4.3 ng/mL vs 0.4 ng/mL). Specific conductance in water was at times higher than the normal range of 0.2 to 0.5 mS/cm but not high enough to affect yields of paddy rice. Total estimated nitrogen concentration often exceeded the 0.86 microg/mL level recommended by EPA for this region. This is a recommended level for states to use in establishing their own standards and varies from region to region. The highest value found was 10.2 microg/mL at tributary site QC at the same time the high value of 123.2 ng/mL for clomazone was found. The total N values then decreased in a first order process over the next 20 days indicating there was likely a one-time introduction of the compound(s) followed by first order dissipation. The highest concentration found on the main Cache was 3.8 microg/mL. Pesticides were found in 25 of the 400 possible detections in sediment. When found, concentrations were low. Of those samples that contained detectable concentrations, the median concentration was 0.056 microg/g. Sediment does not appear to be a sink for sorption of these pesticides which could then be released later. Concentrations of pesticides in the main river varied less and were lower than on tributaries. Tributary site QC had unusually high values for clomazone, imazethapyr, and total nitrogen all on the same date, indicating an isolated event causing the spike in concentrations.
Publications
- Mattice, J.D., Skulman, B.W., Norman, R.J. Environmental implications of pesticides in rice production. B.R. Wells Rice Research Studies. 2009. R.J. Norman, J.-F. Meullenet and K.A.K. Moldenhauer, editors. 123-132.
- Mattice, J.D., Skulman, B.W., Norman, R.J., Gbur, E.E., Jr., Analysis of river water for rice pesticides in eastern Arkansas from 2002 to 2008. Journal of Soil and Water Conservation. 2010. 65(2):130-140.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Water samples were collected every two weeks during the rice growing season from four sites on each of four small rivers in the rice growing region of Arkansas and analyzed for pesticides used in rice production. The four streams that were sampled were relatively small to minimize dilution from water coming from areas not involved in rice production. Results have been submitted for publication in the B.R. Wells Rice Research Studies. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In 2009 there were 99 detections over 2 ppb which is 8.6 % if 100 % were detecting all compounds in all samples. Approximately 71 % of the samples had at least one compound. The most frequently detected compound was quinclorac which was detected in 37 % of the samples. Azoxystrobin was the second most frequently detected compound and clomazone was third. There were 53 samples that contained 1 compound, 18 contained 2 compounds, 2 contained 3 compounds, and 1 contained 4 compounds. Most (90%) of the detections were less than 5 ppb in water, which is a shift toward more concentrations in the low concentration range compared to other years. Most of the detections were from late May to mid July. The highest concentration was 15.4 ppb on April 16 for 2,4-D. Although the Cache River has 25% of the sampling sites, it had 34% of the detections in 2009. Chemicals used properly can benefit society, but if they accumulate in the wrong place at concentrations that are too high, they can have detrimental effects. This work is allowing us to determine if potential environmental problems are developing and will allow us to address them while they are still small and more easily solved.
Publications
- Environmental Implications of Pesticides in Rice Production. J.D. Mattice, B.W. Skulman, and R.J. Norman. B.R. Wells Rice Research Studies 2008. R.J. Norman, J.-F. Meullenet and K.A.K. Moldenhauer, editors. 165-174.
- J.D. Mattice, B.W. Skulman, R. J. Norman, and E. E. Gbur jr. Analysis of river water for rice pesticides in eastern Arkansas from 2002 - 2008. Accepted by Journal of Soil and Water Conservation.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: In 2008, water samples were collected from four sites on each of four rivers in eastern Arkansas during the rice growing season. They were analyzed for 13 pesticides and pesticide degradates used in rice production. The clomazone metabolite, 5-ketoclomazone, has been synthesized and the structure confirmed. The stability of 5-ketoclomazone in water has been measured, and the toxicity of the aqueous degradate of 5-ketoclomazone toward both clomazone resistant and susceptible barnyardgrass is being determined. Results as of Fall, 2008, for both projects were presented at the Weed Science workshop held at the University of Arkansas in the fall of 2008. A preliminary report for the water monitoring project has been submitted to the Arkansas Rice Research and Promotion Board, and the final report is being written. PARTICIPANTS: John D. Mattice, PI, analyzes water samples for rice pesticides for the water monitoring project. Analyzes water and plant tissue samples for clomazone and metabolites and degradates of clomazone. In collaboration with Jason Norsworthy designs and helps execute bioassays to determine phytotoxicity of rice, susceptible, and resistant barnyardgrass to compounds. Synthesized and purified the clomazone metabolite 5-ketoclomazone. In collaboration with Matt McIntosh has tentatively identified, pending further spectral data, the two degradates of the 5-ketoclomazone metabolite. Performed instrumental analysis of soil extracts containing pyrene. Jason Norsworthy initiated work on the clomazone project. Performs screening to identify resistant populations of barnyardgrass and obtains seed. Helps design experiments to measure activity and helps evaluate results. Matt McIntosh provides facilities and assistance for synthesizing the 5-ketoclomazone. Obtains nmr and Ir spectra of products. Provides expertise on potential behavior of these compounds in biological systems. Briggs Skullman collects water samples and performs extractions for instrumental analysis. Helps design and set up bioassays. Collaboration is with the University of Arkansas chemistry department where Dr. McIntosh works. A graduate student in his department will receive some training by obtaining spectra and synthesizing other compounds. TARGET AUDIENCES: The Arkansas Rice Research and Promotion Board is the target audience for the water monitoring project PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The outcome for the rice water monitoring is adding to the data base we have established showing the year to year variability in the parameters we are measuring in river water. These parameters include the highest concentrations detected each year, the most frequently detected compound, detection of the same compound on consecutive sampling dates, overall frequency of detection of compounds, percent distribution of concentrations in different concentration ranges, number of samples with multiple compounds. This year the frequency of detection of pesticides at a concentration of 2 ppb or more was 5.2% where 100% would occur if every compound were found in every sample. Eighty-eight percent of detections were less than 10 ppb, and 12% were between 10 and 30 ppb. Quinclorac was the most frequently detected compound with 33 detections. Of the samples that contained a compound, 40% contained more than one compound. Quinclorac and clomazone were most frequently detected on consecutive sampling dates. These were the two most frequently detected compounds and it occurred on the two rivers with the most detections. The 5-ketoclomazone project is showing that the metabolite has phytotoxic activity toward barnyardgrass. A degradate of the metabolite may also have activity. Experiments to provide data for dose-response curves of these compounds toward rice, susceptible barnyardgrass, and resistant barnyardgrass are underway. The stability of the metabolite in water and methanol has been measured. Knowing with certainty which compound(s) have activity may help use understand why some populations of barnyardgrass are developing resistance and also help us design a remedy.
Publications
- J.D. Mattice, B.W. Skulman, and R.J. Norman. (2008) Environmental Implications of Pesticides in Rice Production. Project report - February, 2008 B.R. Wells Rice Research Studies. 560:103-112.
- Thompson, Oriana A.; Wolf, Duane C.; Mattice, John D.; Thoma, Gregory J. (2008). Influence of Nitrogen Addition and Plant Root Parameters on Phytoremediation of Pyrene-contaminated Soil. Water, Air, & Soil Pollution, 189(1-4), 37-47.
- David Gealy, Karen Moldenhauer, John Mattice, and Wengui Yan. 2008. Developments in Rice Allelopathy: Searching for the Balance between Allelopathic Activity, Agronomic Viability and Commercial Acceptability. Keynote oral presentation at 5th world congress on allelopathy. Dr. Gealy was presenter.
- Duane C. Wolf, Kaaron J. Davis, John D. Mattice, Seong-Jae Kim, Of-Gew Kweon, Carl E. Cerniglia, and Greg J. Thoma. 2008. Pyrene biodegradation in two soils. Soil Science Society of America, abstract.
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Progress 01/01/07 to 12/31/07
Outputs
Water samples were collected every two weeks during the rice growing season from four sites on each of four small rivers in the rice growing region of Arkansas and analyzed for pesticides used in rice production. The four streams that were sampled were relatively small to minimize dilution from water coming from areas not involved in rice production. Results have been presented to producers at the Rice Field Days at Stuttgart, Arkansas, and are also posted at http://www.uark.edu/ua/ricepest/ricewater.html.
Impacts
In 2007 there were 102 detections over 2 ppb which is 6.3 % if 100 % were detecting all compounds in all samples. Approximately 57 % of the samples had at least one compound. The most frequently detected compound was quinclorac which was detected in 24 % of the samples. There were 46 samples that contained 1 compound, 25 contained 2 compounds, and 2 contained 3 compounds. Most (75 %) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentration was 25.5 ppb on June 20 for 2,4-D. Chemicals used properly can benefit society, but if they accumulate in the wrong place at concentrations that are too high, they can have detrimental effects. This work is allowing us to determine if potential environmental problems are developing and will allow us to address them while they are still small and more easily solved.
Publications
- Research Series 550, B.R. Wells Rice Research Series 2006, (August 2007), R.J. Norman, J.-F. Meullenet and K.A.K. Moldenhauer, editors. 197-204.
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Progress 01/01/06 to 12/31/06
Outputs
Water samples were collected every two weeks during the rice growing season from four sites on each of four small rivers in the rice growing region of Arkansas and analyzed for pesticides used in rice production. The four streams that were sampled were relatively small to minimize dilution from water coming from areas not involved in rice production. In 2006 there were 59 detections over 2 ppb which is 3.3 percent if 100 percent were detecting all compounds in all samples. Approximately 40 percent of the samples had at least one compound. The most frequently detected compound was clomazone which was detected in 20 percent of the samples. There were 44 samples that contained 1 compound, 6 contained 2 compounds, and 1 contained 3 compounds. Most (81 percent) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentration was 18 ppb in May for clomazone.
Impacts
Chemicals used properly can benefit society, but if they buildup in the wrong place at concentrations that are too high, they can have detrimental effects. This work will allow us to determine if potential problems are developing and allow us to address them while they are still small and more easily solved.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Water samples were collected every two weeks during the rice growing season from four sites on each of four small rivers in the rice growing region of Arkansas and analyzed for pesticides used in rice production. In 2005 there were 37 detections over 2 ppb which is 2.1 % if 100 % were detecting all compounds in all samples. Approximately 24 % of the samples had at least one compound. The most frequently detected compound was clomazone which was detected in 23 % of the samples. There were 26 samples that contained 1 compound, 4 contained 2 compounds, and 1 contained 3 compounds. The four streams that were sampled were relatively small to minimize dilution effects from a large body of water. Most (65 %) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentration was 20.9 ppb in on May 25 for clomazone.
Impacts
Chemicals used properly can benefit society, but if they buildup in the wrong place at concentrations that are too high, they can have detrimental effects. This work will allow use to determine if potential problems are developing and allow us to address them while they are still small and more easily solved.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/30/04
Outputs
Water samples were collected every two weeks during the rice growing season from four sites on each of four small rivers in the rice growing region of Arkansas and analyzed for pesticides used in rice production. In 2004 there were 77 detections over 2 ppb which is 5.4 % if 100 % were detecting all compounds in all samples. Approximately 44 % of the samples had at least one compound. The most frequently detected compound was quinclorac which was detected in 26 % of the samples. There were 63 samples that contained 1 compound and 14 contained 2 compounds. The four streams that were sampled were relatively small to minimize dilution effects from a large body of water. Most (82 %) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentration was 13 ppb in late July for quinclorac.
Impacts
Chemicals used properly can benefit society, but if they buildup in the wrong place at concentrations that are too high, they can have detrimental effects. This work will allow use to determine if potential problems are developing and allow us to address them while they are still small and more easily solved.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Water samples were collected every two weeks during the rice growing season from four sites on each of four small rivers in the rice growing region of Arkansas and analyzed for pesticides used in rice production. In 2003 there were 79 detections over 2 ppb which is 6.2 % if 100 % were detecting all compounds in all samples. Approximately 48 % of the samples had at least one compound. The most frequently detected compound was quinclorac which was detected in 37 % of the samples. There were 49 samples that contained 1 compound, 9 contained 2 compounds, and 1 each contained 3, 4, and 5 compounds. The four streams that were sampled were relatively small to minimize dilution effects from a large body of water. Most (87 %) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentration was 13 ppb in late July for molinate. A procedure for the analysis of several forms of the naturally occurring antibiotic
bacitracin in poultry litter using HPLC post-column derivatization with fluorescence detection procedure has been developed.
Impacts
Chemicals used properly can benefit society, but if they buildup in the wrong place at concentrations that are too high, they can have detrimental effects. This work will allow use to determine if potential problems are developing and allow us to address them while they are still small and more easily solved.
Publications
- Scott A. Senseman, Thomas C. Mueller, Melissa B. Riley, R. Don Wauchope, Chris Clegg, Roddy W. Young, Lloyd M. Southwick, H. Anson Moye, Jose A. Dumas, Wondi Mersie, John D. Mattice, Ross B. Leidy. 2003. Interlaboratory comparison of extraction efficiency of pesticides from surface and laboratory water using solid-phase extraction disks. J. Agric. Food Chem. 51, 3748-3752.
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Progress 01/01/02 to 12/31/02
Outputs
Water samples were collected every two weeks during the rice growing season from four sites on each of three small rivers in the rice growing region of Arkansas and analyzed for pesticides used in rice production. In 2002 there were 49 detections over 2 ppb which is 5.1 % if 100 % were detecting all compounds in all samples. Approximately 35 % of the samples had at least one compound. The most frequently detected compound was quinclorac which was detected in 29 % of the samples. There were 23 samples that contained 1 compound, 9 contained 2 compounds, 1 contained 3 compounds, and 1 contained 5 compounds. The three streams that were sampled were relatively small to minimize dilution effects from a large body of water. Most (78 %) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentration was 38 ppb in June for clomazone.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Water samples were collected every two weeks during the rice growing season from eight sites in the rice growing region of Arkansas and analyzed for pesticides used in rice production. In 2001 there were 68 detections over 2 ppb which is 12 % if 100% were detecting all compounds in all samples. Approximately 51% of the samples had at least one compound. The most frequently detected compound was quinclorac which was detected in 36% of the samples. There were 18 samples that contained 1 compound, 7 contained 2 compounds, 6 contained 3 compounds, 2 contained 4 compounds, and 2 contained 5 compounds. The two streams that were sampled were relatively small to minimize dilution effects from a large body of water. Most (71%) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentration was 48 ppb in July for molinate. The third year has been completed on a study to compare conventionally tilled cotton to no
till cotton on runoff of sediment and chemicals into an adjacent bayou. Parameters that are being investigated are total suspended solids, pH, conductivity, turbidity, alkalinity, nitrate, total phosphorous, potassium, and aldicarb, pyrithiobac, cyanazine, dicamba, and fluometuron. In the spring and early summer there is only 10 to 20 percent as much TSS leaving the conservation tilled fields as there is leaving the conventionally tilled fields. Later in the summer when the fields are more similar, plant cover and roots holding the soil, the runoff is more similar.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/00 to 12/31/00
Outputs
Water samples were collected every two weeks during the rice growing season from eight sites in the rice growing region of Arkansas and analyzed for pesticides used in rice production. In 2000 there were 53 detections over 2 ppb which is 9.2% if 100% were detecting all compounds in all samples. Approximately 63% of the samples had a least one compound. The most frequently detected compound was molinate which was detected in 39% of the samples. Of the 64 samples 28 contained 1 compound, 11 contained 2 compounds, and 1 contained 3 compounds. The two streams that were sampled were relatively small to minimize dilution effects from a large body of water. Most (72%) of the detections were less than 5 ppb in water. Most of the detections were from late May to mid July. The highest concentrations were in July for molinate with the highest concentration being 46 ppb. The second year has been completed on a study to compare conventionally tilled cotton to no till cotton on
runoff of sediment and chemicals into an adjacent bayou. Parameters that are being investigated are total suspended solids, pH, conductivity, turbidity, alkalinity, nitrate, total phosphorous, potassium, and aldicarb, pyrithiobac, cyanazine, dicamba, and fluometuron. The amount of sediment leaving the field in the conventionally tilled fields is at least twice as much as leaving the fields in the no till production fields, especially early in the season.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/99 to 12/31/99
Outputs
Water samples were collected every two weeks during the rice growing season from six sites in the rice growing region of Arkansas and analyzed for pesticides used in rice production. Over a three year period there have been 66 detections which is 3.6 percent if 100 percent were detecting all compounds in all samples. Approximately 29 percent of the samples had a least one compound. The most frequently detected compound was molinate which was detected in 18.2 percent of the samples. There were four instances where the same compound was detected in the same location in two consecutive sampling periods and once where a compound was detected in three consecutive periods. There were more detections in the two smaller streams which may be due to a dilution in the larger rivers. Most of the detections were less than 5 ppb in water. There does not appear to be any trend in change of frequency of detections or change in concentrations detected over time. The first year has
been completed on a study to compare conventionally tilled cotton to no till cotton on runoff of sediment and chemicals into an adjacent bayou. Parameters that are being investigated are total suspended solids, pH, conductivity, turbidity, alkalinity, nitrate, total phosphorous, potassium, and aldicarb, pyrithiobac, cyanazine, and fluometuron. Analysis of the first year's data has not been completed.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/98 to 12/31/98
Outputs
Some varieties of rice inhibit the growth of ducksalad and barnyardgrass either by allelopathy or competition. We have been searching for the compounds causing the effect if it is due to allelopathy. We are also attempting to assay rice leaf tissue in a manner not destructive to the plant to analyze for compounds that correlate with the effect whether they are the causative compounds or simply correlate with the effect. We have found 5 compounds in HPLC chromatograms that are present in much larger amounts in leaf extracts of rice plants showing the effect than in varieties that do not show the effect. In some cases the compounds are completely absent in the varieties not showing the effect. These compounds may serve as a marker to screen for weed controlling varieties of rice. Since the assay is nondestructive to the plant, it may also be able to identify individual plants that will show strong weed control activity. This would help breeders choose the best plants to
use to incorporate this trait into commercially useful rice. A monitoring program is in effect to measure frequency and water concentration of pesticides at six sampling sites in the rice growing region of Arkansas. Samples were collected at approximately 2 week intervals during the growing season during 1997 and 1998 and analyzed for 17 different pesticides. To date there have been detections in 2.7% of the instances where there could have been a detection. Approximately 25% of the compounds had a detection of at least one compound. The most frequently detected compound was molinate, which was found in 12.7% of the samples. Consecutive detections of the same compound at the same site occurred only for thiobencarb which was detected on June 3 (1 ppb), June 17 (0.5 ppb), and July 1 (1.4 ppb), 1997 at the same location. Work has just begun on a project to look at the effect of conventional till, reduced till, and no till management practices in cotton on the amount of pesticides,
sediment, and nutrients leaving the field as a function of management type.
Impacts
(N/A)
Publications
- Mattice, J.D., Park, S.K., and Lavy, T.L. 1998. Potential passive Empore C18 disk extraction for analysis of water containing fine particulates. Bull. Environ. Contam. Toxicol. 60:202-208.
- Book chapter. Searching for allelochemicals in rice that control ducksalad, Olofsdotter M., editor. 1998. Allelopathy in rice. Proceedings of the Workshop on Allelopathy in Rice, 25-27 Nov 1996. Manila (Philippines) International Rice Research Institute. 154 p (Pages 81-98).
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