Adsorption-desorption and leaching behavior of diuron on selected Kenyan agricultural soils.

In this work, the adsorption-desorption dynamics of diuron in three typical Kenyan agricultural soils, Nzoia (NZ), Thika (TH) and Machakos (MK) was investigated. The equilibrium adsorption data, tested against three classical nonlinear adsorption isotherms, was best described by the Freundlich model. The Freundlich adsorption constant, (K), increased in the order MK > TH > NZ soil.

Insights on adsorption of carbamazepine onto iron oxide modified diatomaceous earth: Kinetics, isotherms, thermodynamics, and mechanisms.

To ameliorate adsorbent recovery by an external magnetic field, naturally occurring diatomaceous earth (DE) was modified with iron-oxide, characterized and applied for adsorption of carbamazepine (CBZ) from synthetic wastewater using batch equilibration method. The fabricated adsorbent was characterized using XRF, XRD, SEM-EDX, FT-IR, BET surface area analysis, VSM and pH of point of zero charge (pH) determination. The adsorption rate was described by the pseudo-first-order (PFO) model suggesting a physisorption controlled rate-determining step.

Biodegradation of carbofuran in soils within Nzoia River Basin, Kenya.

Carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) has been used within the Nzoia River Basin (NRB), especially in Bunyala Rice Irrigation Schemes, in Kenya for the control of pests. In this study, the capacity of native bacteria to degrade carbofuran in soils from NRB was investigated. A gram positive, rod-shaped bacteria capable of degrading carbofuran was isolated through liquid cultures with carbofuran as the only carbon and nitrogen source.

Chlorpyrifos degradation in soils with different treatment regimes within Nzoia River Drainage Basin, Kenya.

Two organic amendments, filter mud compost and Tithonia diversifolia leaves generated within a sugarcane growing area were used to enhance the degradation of chlorpyrifos in soil. Filter mud compost and T. diversifolia leaves significantly enhanced degradation of chlorpyrifos in soils (p < 0.

The dissipation of carbofuran in two soils with different pesticide application histories within Nzoia River Drainage Basin, Kenya.

The dissipation of carbofuran from soils within the Nzoia River Drainage Basin in Kenya was studied under real field conditions for 112 days. Results showed significantly enhanced dissipation of carbofuran with half life (DT50) values of 8 days (p = 0.038) in soils with prior exposure to carbofuran compared to 19 days in soils with no application history.

Effects of carbon amendment on in situ atrazine degradation and total microbial biomass.

This study elucidates the effects of carbon amendment on metabolic degradation of atrazine (6-chloro-N(2)-ethyl-N(4)-isopropyl-1,3,5-triazine-2,4-diamine) and total microbial biomass in soil. Degradation of (14)C-ring-labelled atrazine was monitored in laboratory incubations of soils supplemented with 0, 10, 100 and 1000 μg g(-1) sucrose concentrations. An experiment to determine the effect of carbon amendment on total microbial biomass and soil respiration was carried out with different concentrations of sucrose and non-labelled atrazine.

Biodegradation of s-triazine herbicide atrazine by Enterobacter cloacae and Burkholderia cepacia sp. from long-term treated sugarcane-cultivated soils in Kenya.

In this study soils from sugarcane-cultivated fields were screened for bacterial species capable of atrazine (6-chloro-N²-ethyl-N⁴-isopropyl-1,3,5-triazine-2,4-diamine) degradation due to long exposure of the soils to this herbicide. To enrich for atrazine degraders, Minimal Salt Medium containing atrazine as the sole N source and glucose as the C source was inoculated with soils impacted with this herbicide and incubated. Bacterial growth was monitored by measuring optical density.

The dissipation of hexazinone in tropical soils under semi-controlled field conditions in Kenya.

The dissipation of hexazinone (Velpar) in two tropical soil types in Kenya was studied under field and semi-controlled conditions for a period of 84 days. The dissipation was found to be very rapid and this could be attributed to adverse weather conditions including high initial rainfall as well as to low soil-organic-matter content, volatilization, surface run-off and biodegradation. The DT(50) values of dissipation obtained by first order kinetics were 20 days and 21.