Environmental dynamics of Benomyl and Thiabendazole

The comprehensive environmental dynamics of the heterocyclic Benzimidazole fungicides, Benomyl and Thiabendazole was investigated. This included examining their fate and distribution in the terrestrial and aquatic phases of a laboratory microcosm comprised of silty clay loam soil and plants. The soil component constituted a major relocation site, with approximately 45 and 75% of initial Benomyl (recovered as MBC) and Thiabendazole concentrations being recovered from the soil component of the microcosm, respectively, while 53 and 27% translocated into corn plants. The adsorption mechanism/s of these fungicides onto soil components were investigated using silty clay loam, silty loam and sandy soils as well as Ca-bentonite. These studies indicated that both fungicides were adsorbed to the highest degree on silty clay loam, followed by silty loam and sandy soils. Their adsorption on Ca-bentonite was found to be a function of the pH of the suspension, suggesting that in the presence of increasing ll *activity on the clay surfaces, Benomyl and Thiabendazole become protonated to form positively charged molecules. These may then react with the clay surfaces forming Fungicide-clay complexes. The effect of different CaCl, concentrations on the adsorption process demonstrated that an increase in the salt concentration, at a constant pH resulted in a decrease in the amounts of adsorbed fungicide. The transport of the fungicides (adsorbed onto soil particles) as a consequence of scdiment runoff into aquatic systems was also estimated. Results of the simulation of overland sediment runoff from sections of the Chowan river basin into the Meherrin river following a rainstorm, indicate that significant quantities of Benomyl and Thiabendazole could be transported into aquatic systems. Adsorption studies also indicated that the adsorption process is reversible. Thus, any significant increases in the pH of receiving bodies of water could result in the release of Benomyl and Thiabendazole from sediment causing a contamination of the aquatic system.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Environmental Sciences and Engineering

Department dc:contributor.department

Environmental Sciences and Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1986

Author dc:creator

• Balasubrahmanyam, Sunil K.

Chair dc:contributor.committeechair

• Boardman, Gregory D.

Committee members dc:contributor.committeemember

• Randall, Clifford W.
• Reneau, Raymond B. Jr.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Dc Identifier Other

etd-12182013-040027

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/50496