Bruce T. Bowman, Ph.D.

Environmental Quality, Renewable Energy
Manager, ManureNet and Agri-Environmental Archive
Photo of B.T. Bowman

Retired: August 31, 2006

Agriculture and Agri-Food Canada
London, ON 

 

Contact Bruce: bowmanarchive@gmail.com


Agri-Environmental Archives - Home

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Personal Biography:
  • B.S.A. (General Science), Ont. Agric. College, Univ. of Toronto - 1964
  • M.Sc. (Soil Science), Univ. of Guelph, Guelph, ON - 1966
  • Ph.D. (Soil Science/Analytical Chemistry) - Univ. of Minnesota, St. Paul, Minnesota - 1969


Research Interests:

Transport and dissipation processes of pesticides in soils; use of rainfall simulation techniques for studying the impact of tillage/cropping practices upon pesticide and nutrient movement in soils; use of rainfall simulator/grid lysimeters for the study of preferential water flow processes in soil; use of tension infiltrometers to characterize near-surface porosity of field soils.

Current Specialty:
  • Environmental Quality; Program Management; Information management and Web Site development, specifically related to renewable farm-based bio-energy systems, and sustainable development.

  • Archivist of Ontario Environmental Programs and Their Associated Reports - 1995 - present

Other Professional Activities:
  • Member: American Society of Agronomy (1967- 2008)
  • Scientific Authority, Research Sub-Program, Canada-Ontario Green Plan, 1992 - 1997
  • Member of International Review Panel for Swedish FOOD21 Environmental Program (1996 - 2001)
  • Program Manager, Ontario Research Enhancement Program - 1997 - 2000
  • Chair, Ontario Soil Water and Air Research and Services Committee - 1998 - 2000
  • Member, Waste Utilization Sub-Committee of Ontario Soil Water and Air Research and Services Committee (1997 - 2006).
  • Chair, Expert Committee on Manure Management, Canadian Agri-Food Research Council (CARC) - (1999 - 2006)
  • Member, Expert Committee on Greenhouse Gas Emissions and Carbon Sequestration, CARC - (2000 - 2006)
  • Member of International Scientific Working Group in Sweden, organizing, writing and publishing a 10-chapter publication on Sustainable Nutrient Management (2001-2004)
  • WebMaster for the Southern Crop Protection and Food Research Centre (1995-2002), Canada-Ontario Green Plan, Agri-Environmental Program Archives, and ManureNet Internet Web Sites (1995 - present).

 

Publication List
2005

Bergström, L., Bowman, B.T. & Sims, T. 2005. Definition of sustainable and non-sustainable issues in nutrient management of modern agriculture. Soil Use and Management 21: 76-81

Sims, J.T., Bergström, L., Bowman, B.T. & Oenema, O. 2005. Sustainble nutrient management for intensive animal agriculture: policies and practices for sustainability. Soil Use and Management 21:141-151.

2003

Farenhorst, A., Tomlin, A.D., and Bowman, B.T. 2003. Impact of herbicide application rates and crop residue type on earthworm weights. Bull. Environ. Contam. and Tox. 70(3): 477 - 484.

2002

Reynolds, W.D., B.T. Bowman, C.F. Drury, C.S. Tan and X. Lu. 2002. Indicators of Good Soil Physical Quality: Density and Storage Parameters. Geoderma 110: 131-146.

2000

Farenhorst, A., and B.T. Bowman. 2000. Sorption of Atrazine and Metolachlor by Earthworm Surface Castings and Soil. J. of Environmental Science and Health Part B - Pesticides Food Contaminants and Agricultural Wastes 35 : 157 - 173.

Farenhorst, A, Topp, E., Bowman, B.T., and Tomlin, A.D. 2000. Earthworms and the dissipation and distribution of atrazine in the soil profile. Soil Biology and Biochemistry 32:23 - 33.

Farenhorst, A., E. Topp, B.T. Bowman, and A. D. Tomlin. 2000. Earthworm Burrowing and Feeding Activity and the Potential for Atrazine Transport by Preferential Flow. Soil Biol. and Biochem. 32: 479 - 488.

Reynolds, W.D., B.T. Bowman, R.R. Brunke, C.F. Drury, and C.S. Tan. 2000 . Comparison of tension infiltrometer, pressure infiltrometer, and soil core estimates of saturated hydraulic conductivity. Soil Sci. Soc. Am. J. 64:478-484.

1998

Farenhorst, A., and B.T. Bowman. 1998. Competitive Sorption of Atrazine and Metolachlor in Soil. J. of Environmental Science and Health Part B - Pesticides Food Contaminants and Agricultural Wastes 33 : 671 - 682.

1994

Bowman, B.T.; Brunke, R.R.; Reynolds, W.D.; Wall, G.J. 1994. Rainfall Simulator-Grid Lysimeter System for Solute Transport Studies Using Large, Intact Soil Blocks. Journal of Environmental Quality 23:815 - 822.
 
View / Download Full Paper  [326 KB pdf]

Bowman, B.T., G.J. Wall, and D.J. King. 1994. Transport of herbicides and nutrients in surface runoff from corn cropland in southern Ontario. Can. J. Soil Sci. 74: 59 - 66.

Agyei, E.O., R.P. Rudra, W.T. Dickinson, B.T. Bowman and R. K. Gupta. 1994. Analysis and modeling of preferential flow. Paper - Amer. Soc. Agricultural. Engineers No. 94-2180: 9pp

1993

Bowman, B.T. 1993. Effect of formulation upon movement and dissipation of 14C-metolachlor and atrazine in field lysimeters. Can. J. Soil Sci. 73: 309 - 316.
  
View / Download Full Paper [164 KB pdf]

1992

Bowman, B.T. 1992. Mobility and persistence of isazofos in granular and microencapsulated formulations in two soils, using field lysimeters. Pesticide Sci. 36: 181 - 188.
 
View / Download Full Paper [223 KB pdf]

Bowman, B.T. 1992. Use of computer spreadsheet template to evaluate drifting gas-liquid chromatograph or high-pressure liquid chromatograph detector responses of pesticides. J. Chromat. Sci. 30: 184 - 186.
  View / Download Full Paper  [222 KB pdf]

1991

Bowman, B.T. 1991. Use of field lysimeters for comparison of mobility and persistence of granular and EC formulations of the soil insecticide isazofos. Environ. Toxicol. Chem. 10: 873 - 879.
 
View / Download Full Paper  [190 KB pdf]

Bowman, B.T. 1991. Mobility and dissipation studies of metribuzin, atrazine and their metabolites in plainfield sand, using field lysimeters. Environ. Toxicol. Chem. 10: 573 - 579.
 
View / Download Full Paper  [191 KB pdf]

1990

Bowman, B.T. 1990. Mobility and Persistence of alachlor, atrazine, and metolachlor in Plainfield sand, and atrazine and isazofos in Honeywood silt loam, using field lysimeters. Environ. Toxicol. Chem. 9: 453 - 461
 
View / Download Full Paper  [531 KB pdf]

1989

Bowman, B.T. 1989. Mobility and persistence of the herbicides atrazine, metolachlor and terbuthylazine in plainfield sand lysimeters. Environ. Toxicol. Chem. 8: 485 - 491.
  View / Download Full Paper [384 KB pdf]

1988

Bowman, B.T. 1988. Mobility and persistence of metolachlor and aldicarb in field lysimeters. J. Environ. Qual. 17: 689-694View / Download Full Paper  [239 KB pdf]

1985

Bowman, B.T. and W.W. Sans. 1985. Effect of temperature on the water solubility of insecticides. J. Environ. Sci. Health B20: 625 - 631.
  View / Download Full Paper [37 KB pdf]

Bowman, B.T. and W.W. Sans. 1985. Partitioning behavior of insecticides in soil-water systems. 1. Adsorbent concentration effects. J. Environ. Qual. 14: 265 - 269.
  View / Download Full Paper [68 KB pdf]

Bowman, B.T. and W.W. Sans. 1985. Partitioning behavior of insecticides in soil-water systems. 2. Desorption hysteresis effects. J. Environ. Qual. 14: 270 - 273. see additional notes below  
  View / Download Full Paper [56 KB pdf]

1984

Bowman, B.T. 1984. Numerical technique for estimating equilibrium concentrations from initial concentrations when using the Freundlich adsorption equation. J. Environ. Sci. Health B19: 313 - 321.
  View / Download Full Paper  [34 KB pdf]

1983

Bowman, B.T. and W.W. Sans . 1983. Determination of octanol-water partitioning coefficients (Kow) of 61 organophosphorus and carbamate insecticides and their relationship to respective water solubility (S) values. J. Environ. Sci. Health B18: 667 - 683 View / Download Full Paper  [80 KB pdf]

Bowman, B.T. and W.W. Sans. 1983. Further water solubility determinations of insecticidal compounds. J. Environ. Sci. Health B18: 221 - 227. View / Download Full Paper  [26 KB pdf]

1982

Bowman, B.T. 1982. Conversion of Freundlich adsorption K values to the mole fraction format and the use of Sy values to express relative adsorption of pesticides. Soil Sci. Soc. Amer. J. 46: 740 - 743.
  View / Download Full Paper  [80 KB pdf]

Bowman, B.T. and W.W. Sans . 1982. Adsorption, desorption, soil mobility, aqueous persistence and octanol-water partitioning coefficients of terbufos, terbufos sulfoxide and terbufos sulfone. J. Environ. Sci. Health B17: 447 - 462.   View / Download Full Paper  [70 KB pdf]

Bowman, B.T. and W.W. Sans . 1982. Influence of methods of pesticide application on subsequent desorption from soils. J. Agric. Food Chem. 30: 147 - 150.
  View / Download Full Paper  [91 KB pdf]

1981

Bowman, B.T.1981. Anomalies in the log Freundlich equation resulting in deviations in adsorption K values of pesticides and other organic compounds when the system of units is changed. J. Environ. Sci. Health B16: 113 - 123.   View / Download Full Paper  [63 KB pdf]

Harris C.R. and B.T. Bowman. 1981. The relationship of insecticide solubility in water to toxicity in soil. J. Econ. Entomol. 74: 210-212. View / Download Full Paper  [69 KB pdf]

Miles, J.R.W., B.T. Bowman, and C.R. Harris. 1981. Adsorption, desorption, soil mobility and aqueous persistence of fensulfothion and its sulfide and sulfone metabolites. J. Environ. Sci. Health B16: 309-324.
  View / Download Full Paper  [129 KB pdf]

1980

Bowman, B.T. and W.W. Sans. 1980. The stability of parathion and DDT in dilute iron solutions. J. Environ. Sci. Health B15: 233-246.  View / Download Full Paper  [117 KB pdf]

1979

Bowman, B.T. and W.W. Sans. 1979. The aqueous solubility of twenty-seven insecticides and related compounds. J. Environ. Sci. Health B14: 625-634.  View / Download Full Paper  [31 KB pdf]

Bowman, B.T. 1979. Method of repeated additions for generating pesticide adsorption-desorption isotherm data. Can. J. Soil Sci. 59: 435-437. View / Download Full Paper  [53 KB pdf]

1978

Bowman, B.T. 1978. Effect of fulvic acid on adsorption of methyl parathion and parathion by Ca2+- and Fe3+-montmorillonite suspensions. Soil Sci. Soc. Amer. J. 42: 441-446.
  View / Download Full Paper  [101 KB pdf]

1977

Bowman, B.T. and W.W. Sans. 1977. Adsorption of parathion, fenitrothion, methyl parathion, aminoparathion and paraoxon by Na+, Ca2+, and Fe3+ montmorillonite suspensions. Soil Sci. Soc. Amer. J. 41: 514-519.
  View / Download Full Paper  [100 KB pdf]

1976

Harris, C.R. and B.T. Bowman. 1976. Influence of cation content on the biological activity of fensulfothion in Plainfield sand. Soil Sci. Soc. Amer. J. 40: 385-389.   View / Download Full Paper  [78 KB pdf]

Up to 1975

Bowman, B.T. 1975. Effects of method of clay preparation on subsequent adsorption of the insecticide fensulfothion. Can. J.Soil Sci. 55: 105-110.  View / Download Full Paper  [98 KB pdf]

Bowman, B.T. 1973. The effect of saturating cations on the adsorption of Dasanit, 0,0-diethyl 0-[p-(methylsulfinylphenyl] phosphorothioate, by montmorillonite suspensions. Soil Sci. Soc. Amer. Proc. 37: 200-207.  View / Download Full Paper  [125 KB pdf]

Bowman, B.T., Russell S. Adams, Jr., and Stuart W. Fenton. 1970. Effect of water on malathion adsorption onto five montmorillonite systems. J. Agric. Food Chem. 18: 723-727.
  View / Download Full Paper  [129 KB pdf]

Bowman, B.T., R.L. Thomas, and D.E. Elrick. 1967. The movement of phytic acid in soil cores. Soil Sci. Soc. Amer. Proc. 31: 477-481.  View / Download Fulll Paper  [123 KB pdf]

Thomas, R.L. and B.T. Bowman. 1966. The occurrence of high molecular weight organic phosphorus compounds in soil. Soil Sci. Soc. Amer. Proc. 30: 799-801.

 

Ph.D. Thesis

THE EFFECT OF WATER UPON MALATHION ADSORPTION ONTO FIVE MONTMORILLONITE SYSTEMS - B.T. Bowman, Ph.D. Thesis, December 1969, University of Minnesota
   View / Download Thesis  [1579 KB pdf] 


Posters

Preferential Water Flow and Solute Transport Studies Using Large Intact Soil Block Lysimeters - G. Reinken, B.T. Bowman, R.R. Brunke, W.D. Reynolds and F. Führ - presented at 1998 American Society of Agronomy Meetings, Oct. 18-23, 1998, Baltimore, MD.


Some Abstracts:

Farenhorst, A., and B.T. Bowman. 2000. Sorption of Atrazine and Metolachlor by Earthworm Surface Castings and Soil. J. of Environmental Science and Health Part B - Pesticides Food Contaminants and Agricultural Wastes 35 : 157 - 173.

Atrazine and metolachlor were more strongly retained on earthworm (Lumbricus terrestris L.) castings than on soil, suggesting that earthworm castings at the surface or at depth can reduce herbicide movement in soil. Herbicide sorption by castings was related to the food source available to the earthworms. Both atrazine and metolachlor sorption increased with increasing organic carbon (C) content in castings, and Freundlich constants (Kf values) generally decreased in the order: soybean-fed > corn-fed > not-fed-earthworm-castings. The amount of atrazine or metolachlor sorbed per unit organic carbon (Koc values) was significantly greater for corn-castings compared with other castings, or soil, suggesting that the composition of organic matter in castings is also an important factor in determining the retention of herbicides in soils. Herbicide desorption was dependent on both the initial herbicide concentration, and the type of absorbent. At small equilibrium herbicide concentrations, atrazine desorption was significantly greater from soil than from any of the three casting treatments. At large equilibrium herbicide concentrations, however, the greater organic C content in castings had no significant effect on atrazine desorption, relative to soil. For metolachlor, regardless of the equilibrium herbicide concentration, desorption from soybean- and corn-castings treatments was always less than desorption from soil and not-fed earthworm castings treatments. The results of this study indicate that, under field conditions, the extent of herbicide retention on earthworm castings will tend to be related to crop and crop residue management practices.
 

Farenhorst, A., E. Topp, B.T. Bowman, and A.D. Tomlin. 2000. Earthworms and the dissipation and distribution of atrazine in the soil profile. Soil Biology and Biochemistry 32:23 - 33.

The influence of earthworms (Lumbricus terrestris L.) on the persistence and transport of 14C-labelled atrazine [2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine] in soil was studied in laboratory incubations using flask microcosms, and packed columns. In soil microcosm incubations (12°C or 30°C), [U-ring-14C]atrazine was dissipated and mineralized more rapidly in soil pre-incubated with earthworms (e.g. soil containing worm castings) than in soil without earthworms. Earthworms added to soil following herbicide application accelerated the formation of non-extractable (soil-bound) atrazine residues, as well as reducing atrazine mineralization rates, compared to soil that did not contain earthworms. In packed soil columns (24 cm x 6.3 cm i.d. diameter), earthworms promoted the formation of non-extractable residues, and modified the vertical distribution of herbicide residues. Following a 68-d incubation of soil columns (12°C) receiving a surface application of [U-ring-14C]atrazine-sprayed corn leaves, total non-extractable radioactivity in soil columns containing earthworms was 21% greater than that in soils without earthworms. Earthworm consumption of the [U-ring-14C]atrazine-sprayed corn leaves and subsequent activity translocated 60% of the total radioactivity below 4 cm. In contrast, more than 65% of the initially applied [U-ring-14C]atrazine remained in the top 4 cm surface layer in columns containing no earthworms. Earthworms also influenced the distribution of herbicide residues in the soil matrix, depositing about twice as much MeOH-extractable radioactivity in their burrow linings as in the surrounding soil. The implications of these findings for weed and environmental management are discussed.

Farenhorst, A., E. Topp, B.T. Bowman, and A. D. Tomlin. 2000. Earthworm Burrowing and Feeding Activity and the Potential for Atrazine Transport by Preferential Flow. Soil Biol. and Biochem. 32: 479 - 488.

Soil columns with established burrow structures were subjected to 14 and 47 mm h-1 rainstorms to study the impact of Lumbricus terrestris L. feeding activity on preferential atrazine transport in soil. Earthworm treatments for the soil columns were as follows: earthworms introduced one day prior to herbicide applications, earthworms introduced nine days after herbicide applications, and earthworm-free soils. Rainfall was applied at 9, 18, 29, 40, and 51 days following [U-ring-14C]atrazine applications onto crop residues at the soil surface. Concentration of radioactivity in leachate was greatest during the first rainfall simulation and decreased through four subsequent simulated rainfall simulations. Preferential herbicide transport through earthworm burrows occurred during all rainfall simulations, but total atrazine and metabolites in leachate at the end of five rainfall simulations were approximately 2× greater in the absence than in the presence of earthworms. Earthworm feeding activity reduced the potential for herbicide leaching by ingesting and transporting herbicide residues away from the soil surface, and increasing the amount of non-extractable (non-leachable) herbicide residues in the soil. For a more realistic assessment of herbicide movement in no-till soils, studies using intact soil columns should include representatives of the native earthworm population to account for their contribution to herbicide leaching.

Farenhorst, A., and B.T. Bowman. 1998. Competitive Sorption of Atrazine and Metolachlor in Soil. J. Environ. Sci. & Health B33(6): 671 - 682.

Atrazine and metolachlor co-application to soil created competitive sorption between the two herbicides, producing smaller partitioning coefficients than for separate atrazine and metolachlor applications. The partitioning coefficients for both compounds were also less when applied in a commercial formulation, compared with separate analytical-grade applications. Since the Freundlich slope of the isotherms was less than unity (0.83 to 0.87), the sorption strength of the herbicides decreased with increasing solution concentrations. Based on the Freundlich adsorption values obtained, this study concludes that atrazine and metolachlor co-applications on agricultural fields have the potential to increase the mobility of these herbicides in soil, thereby also increasing the risk for groundwater contamination.

Bowman, B.T.; Brunke, R.R.; Reynolds, W.D.; Wall, G.J. 1994. Rainfall Simulator Grid Lysimeter System for Solute Transport Studies Using Large, Intact Soil Blocks. Journal of Environmental Quality 23:815 - 822

A grid lysimeter system and sample collection, containment, and storage techniques were developed for detailed laboratory studies of water and solute movement through intact soil blocks. This was done because existing designs and techniques bad important deficiencies and were limited in their range of capabilities. Intact 46-cm soil cubes were isolated, then contained within a polyurethane foam shell, which formed a stable, intimate soil bond, was impermeable to water and strong enough to support a large soil block, while sufficiently elastic to accommodate soil shrink-swell with changing water content without rupturing. The soil blocks were instrumented with solution delivery, collection, and monitoring systems. A dripper-based simulator delivered steady rainfall ranging from 4.8 to 30.0 mm h-1. The solution collection system was a 10 by 10 grid of cells (3.8 by 3.8 by 1.3 cm deep) milled into an aluminum block, which individually drained into collection tubes housed within a vacuum chamber. The collection grid permitted characterization of spatial and temporal water and solute movement through the block. The solution monitoring system consisted of side-by-side tensiometer pairs and time domain reflectometry (TDR) probes inserted horizontally through the foam shell at four depths in the block. As a partial test of the system, a bromide (Br-) tracer breakthough curve (saturated flow) was generated at a simulated rainfall rate of 19.2 mm h-1. Flow data indicated that 85% of the water in the block was bypassed by the Br-, and that >99% of the water flow passed through only 26% of the basal area of the block. The water flow pattern in the solution collector exhibited no evidence of preferential flow along the interface between the soil and the outer polyurethane shell. It was concluded that the rainfall simulator-grid lysimeter system was operating effectively.

Bowman, B.T. 1991. Mobility and dissipation studies of metribuzin, atrazine and their metabolites in plainfield sand, using field lysimeters. Environ. Toxicol. Chem. 10: 573 - 579.

Mobility and persistence of metribuzin (LEXONE DF) and its metabolites (deaminated, DA; diketo, DK; deaminated-diketo, DADK) were studied using 75 cm x 15 cm field lysimeters packed with with Plainfield sand, and subjected to two moisture (rainfall, supplementary watering). Atrazine was applied to lysimeters as an internal reference. Each lysimeter consisted of 24 lysimeters, divided into two moisture of six pairs each. Effluent was monitored for metribuzin, DK, DADK, atrazine and desethylatrazine. Selected core pairs were sectioned (7 x 10 cm) and analyzed to determine mobility persistence for each chemical at weeks 1, 2, 4, 8, 12 and 21. No chemicals moved more than 30 cm, nor were detected in effluent of cores receiving rainfall. In cores supplementary watering, substantial amounts of metribuzin moved more than 30 cm by week 2 and eluted on 21 occasions during the study. DADK and DK were much more mobile than metribuzin in the lysimeters, eluting more frequently than metribuzin. Metribuzin and metabolites were considerably more mobile than atrazine or desethylatrazine in Plainfield sand. Metribuzin disappearance closely followed first-order kinetics with T1/2 values of 3.08 and 2.04 weeks, respectively, for rainfall and supplementary watering treatments. The primary degradation pathway for metribuzin was through the DK intermediate rather than the DA intermediate.

Bowman, B.T.1991. Use of field lysimeters for comparison of mobility and persistence of granular and EC formulations of the soil insecticide isazofos. Environ. Toxicol. Chem. 10: 873 - 879.

Mobility and persistence of two formulations of the insecticide isazofos were compared using 75 cm x 15 cm field lysimeters, packed Plainfield sand, and using two moisture regimes (natural rainfall, Supplementary Watering). Atrazine was applied to all lysimeters as an internal reference. Effluent was monitored for isazofos, its metabolite CGA17193, atrazine and desethylatrazine. Selected cores were sectioned and analyzed for each chemical at weeks 1, 2, 4, 8, 12 and 21. None of the applied chemicals or their metabolites leached from soil cores receiving only rainfall throughout the 21 week study. The mobility ranking under Supplementary Watering in Plainfield sand cores was: CGA17193 >>desethylatrazine > atrazine > isazofos EC > isazofos granular. The first-order half-live of isazofos was 2.0 and 2.7 weeks, respectively, in EC and granular formulations. Evaporative losses accounted for 44 to 67 % and 72 to 100 % of incident precipitation on the Supplementary Watering and Rainfall lysimeters, respectively.

Bowman, B.T. and W.W. Sans. 1985. Partitioning behavior of insecticides in soil-water systems. 1. Adsorbent concentration effects. J. Environ. Qual. 14: 265 - 269.

Adsorption studies were conducted to determine whether adsorbent concentration (soil-solution ratio) affected insecticide adsorption by soils and clays. Adsorption isotherms were obtained for several insecticides in Bondhead sandy loam and Ca-saturated illite suspensions using adsorbent concentrations that varied over several orders of magnitude. There was no evidence that altering adsorbent concentration exerted any influence on partitioning of insecticides between the adsorbent and solution phases. The centrifugation process, which in effect greatly increased adsorbent concentration t the bottom of the centrifugation tube, did not change the partitioning of the insecticides between the two phases. Dieldrin (1,2,3,4,10,10-hexachloro -exo-6,7-epoxyl, 4,4a,5,6,7,8,8a-octahydro -1,4-endo,exo-5,8 -dimethanophthalene), unlike the other insecticides, exhibited strong concentration-dependent adsorption by glass surfaces, which invalidated the use of normal "blank" (no adsorbent) sample for determining the initial solute concentration. Since glass adsorption appeared quite irreversible in aqueous solution, a sequential blank/sample adsorption technique was adopted whereby the stock solution was initially equilibrated in the glass bottle, then a small aliquot was removed for analysis before adding the adsorbent for its equilibration period. This technique produced consistent adsorption data that showed no evidence of being influenced by adsorbent concentration.
Additional Index Words: soil-solution ratio, isotherm, adsorption, parathion, dieldrin, chlorpyrifos, fensulfothion sulfone

Bowman, B.T.and W.W. Sans. 1985. Partitioning behavior of insecticides in soil-water systems. 2. Desorption hysteresis effects. J. Environ. Qual. 14: 270 - 273.

This investigation was undertaken to determine whether desorption hysteresis effects were dependent upon methods used in obtaining desorption data. Adsorption-desorption isotherms were obtained for two organophosphorus insecticides in aqueous suspensions of a clay, a sandy loam, and an organic soil. Desorption isotherms were obtained using both the consecutive desorption method and the dilution method. In the consecutive method, the same sample (after adsorption step) was put through a series of equilibrium- centrifugation steps in which, following equilibration, the adsorbent was thrown down by centrifugation, and part of the supernatant pesticide solution was replaced by distilled water before re-equilibration. In the dilution method, a series of replicate samples (same adsorbent weight), after the adsorption step, were diluted to different volumes with distilled water, re-equilibrated, then centrifuged to separate the phases. With the exception of one insecticide-soil system (where both methods produced minimal hysteresis), hysteresis effects were considerably reduced by using the dilution method. Repeated centrifugation appeared to be associated with the appearance of hysteresis effects observed using the consecutive desorption method. A short discussion is included on the improper use of desorption data to construct "single-point desorption isotherms", which has created confusion in the literature (see below). Additional Keywords: irreversibility, non-singularity, isotherm, organic matter.

 

Presentation List

  1. Advances in Manure Management and Areas of Research Need  [86 KB pps] - Climate Change Funding Initiative in Agriculture -  Mid-Program Review,  March 21-22, 2002,  Winnipeg, MB
     

  2. Livestock Manure Treatment Technologies:  Environmental Impacts  [1706  KB pps]- AIC-sponsored "National Conference on Agricultural Nutrients and their Impact on Rural Water Quality", April 30, 2002,  Waterloo, Ontario  
     

  3. ManureNet - A Case Study in Information Sharing  [198 KB pps]- CARC "Knowledge Transfer Workshop", Winnipeg, October 25-27, 2002 
     

  4. Manure Storage, Handling and Application Practices which Mitigate GHG Emissions for Hog Operations.[2062 KB pps]  Workshop on Climate Change Strategy in the Hog Industry, December 9, 2002, Hull, QC   PDF version
     

  5. "An Assessment of the Economics of Adopting Stewardship Practices in Livestock Production, in Response to Environmental and Societal Concerns" [234 KB pps) - A presentation at the Final Workshop of the Climate Change Funding in Agriculture (CCFIA), Winnipeg, MB - Jan. 19, 2004. - An overview of the Discussion Paper + focussed comments on manure policy/regulatory barriers.
     

  6. Manure – A Multi-Purpose Resource: "Things are Changing in the Barnyard! [1387 KB pps] - A presentation to the Soil and Crop Improvement Association of Nova Scotia, Truro, NS, Feb. 22, 2005 
     

  7. Re-defining Confined Livestock Farming: Making Carbon Work for Us. [946 KB pps] - presented at CARC Annual Meeting, Ottawa, ON, April 21, 2005
     

  8. Re-Defining Confined Livestock Farming: Farm-based Renewable Energy Systems [691 KB pps] - A presentation to the Rural Ontario Municipal Association (ROMA), Toronto, Ontario, June 2, 2005
     

  9. Integrated Manure Biogas Systems: Impacts on Farmers & Their Rural Communities [1227 KB pps] - A presentation to the conference, "Enhancing Biogas Opportunities in Alberta", Edmonton, AB April 3, 2006

 


 

Pitfalls in Generating Desorption Isotherms

Taken from:

Bowman, B.T. and W.W. Sans. 1985. Partitioning behavior of insecticides in soil-water systems. 2. Desorption hysteresis effects. J. Environ. Qual. 14: 270 - 273
  View / Download Full Paper [56 KB pdf]

Graphical representation of adsorption-desorption isotherms

In the figure above, a graphical representation of an adsorption-desorption isotherm system is shown, where the "adsorption" branch is depicted by A-B-C. Three desorption isotherms are shown, (A-A1-A2; B-B1-B2; C-C1-C2), each having a "unique", separate origin on the adsorption branch at A,B, & C, respectively. There are numerous references in the literature where researchers have mistakenly joined the "first" desorption points (A1-B1-C1) from their respective adsorption points (A,B,C). This "single-point" desorption (A1-B1-C1), depicted by the dotted line, has "no physical meaning or interpretation".

Desorption isotherms can be constructed ONLY by successive removals of solute from the "same" system, and replacing the volume with water (or weak electrolyte, such a CaCl2). For each adsorption isotherm, it is possible to construct a "family" of desorption isotherms, each with an unique origin on the adsorption branch.

"Single-point" isotherms are easily identified by the fact that their slopes are "greater" than that of the respective adsorption isotherm. In fact, true desorption isotherms always have slopes equal to, or less than the slope of the parent adsorption isotherm.

 

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last revised: 04/07/2017