Kinetic field dissipation and fate of endosulfan after application on theobroma cacao farm in tropical Southwestern Nigeria

Vaikosen, Edebi N. and Olu-Owolabi, Bamidele I. and Gibson, Lorraine T. and Adebowale, Kayode O. and Davidson, Christine M. and Asogwa, Uche (2019) Kinetic field dissipation and fate of endosulfan after application on theobroma cacao farm in tropical Southwestern Nigeria. Environmental Monitoring and Assessment, 191 (3). 196. ISSN 0167-6369 (https://doi.org/10.1007/s10661-019-7293-7)

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Abstract

Endosulfan, 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano,2,4,3-benzodioxathiepin-3-oxide, is still a pesticide of choice for most cocoa farmers in Southwestern Nigeria, in spite of its persistence, bioaccumulative, toxicological properties, and restriction. A single treatment of 1.4 kg ai/ha (0.5% ai) of technical grade endosulfan (Thiodan, 35EC) was applied to 0.0227 ha of cultivated Theobroma cacao L. (Cocoa) farm at the Cocoa Research Institute of Nigeria (CRIN). Levels of parent endosulfan (α-, β-endosulfan) and major metabolite (endosulfan sulfate) were determined in vegetation and surrounding matrices at days 0, 7, 14, 21, 28, 42, and 60 using GC-MS. Their kinetic variables were determined. Order of ∑endosulfan distribution at day 0 was dry foliage > fresh foliage > bark > pods > soil (0–15 cm). No residual endosulfan was found in cocoa seeds and subsurface soil (15–30 cm). Low residual levels in pods on day 0 may be due to endogenous enzymatic breakdown, with α-isomer more susceptible and α/β-endosulfan ratio being 0.90. Fell dry foliage as mulch was predominantly the receiving matrix for non-target endosulfan sprayed. Volatilization was key in endosulfan dissipation between days 0 and 7 from foliage surfaces (> 60% loss), while dissipation trend was bi-phasic and tri-phasic for vegetation and soil, respectively. ∑endosulfan loss at terminal day ranged between 40.60% (topsoil) and 99.47% (fresh foliage). Iteratively computed half-lives (DT′ 50 ) ranged from 6.48 to 30.13 days for ∑endosulfan in vegetation. Endosulfan was moderately persistent in pods—a potential source for cross contamination of seeds during harvest. Iteratively determined DT′ 50 and initial-final day DT 50 are highly correlated (R = 0.9525; n = 28) and no significant difference (P = 0.05) for both methods.

  • Item type:Article
    ID code:67260
    Dates:
    Date
    Event
    1 March 2019
    Published
    27 February 2019
    Published Online
    4 February 2019
    Accepted
    Subjects:Science > Chemistry
    Department:UNSPECIFIED
    Depositing user: Pure Administrator
    Date deposited:12 Mar 2019 11:03
    Last modified:09 Apr 2024 00:35
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/67260
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