Browsing by Author "Cooper, William J."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Effect of pH and dissolved organic matter on the photochemical fate of acetamipridPublication . Pinto, M.I.; Salgado, Ricardo; Laia, C. A. T.; Branco, L.; Vale, C.; Cooper, William J.; Burrows, Hugh D.; Noronha, J. P.In this study the effect of pH and dissolved organic matter (DOM) on the photodegradation rate of acetamiprid (ACT) was studied. Observed photodegradation rate constants in the range of 0.0010 – 0.0026 h-1 and 24 – 36 h-1 were obtained using a solar simulator (290-800 nm) and a medium pressure mercury (MP Hg) lamp, respectively. In both experiments an increase in pH from 5 to 9 did not significantly change the photodegradation rate constant of ACT. A different behaviour was found for ACT degradation in the presence of DOM. When samples were irradiated with MP Hg lamp the observed photodegradation rate constant of ACT decreased with an increase of DOM concentration.
- The effect of chloride ions and organic matter on the photodegradation of acetamiprid in saline watersPublication . Pinto, M. I.; Salgado, Ricardo; Laia, C.A.T.; Cooper, William J.; Sontag, J.; Burrows, Hugh D.; Branco, L.; Vale, C.; Noronha, J. P.The photodegradation kinetics of the neonicotinoid insecticide acetamiprid (ACT) was investigated under different conditions of pH, salinity and dissolved organic matter (DOM). Photodegradation of ACT in saline and freshwaters followed pseudo-first-order kinetics. Varying pH from 5 to 9 did not significantly affect the photodegradation rate constants (kp) of ACT. Addition of chloride ions increased significantly the value of kp. In the presence of AHA, 10 mg L−1, kp was reduced to approximately 34% of that in sodium chloride solutions 35 g L−1 The observed inhibition may be a consequence of the antioxidant properties of DOM and/or the shading of DOM in the solution. In coastal waters, kp showed a tendency to increase with increasing of salinity and to decrease in the presence of DOM. This is an important outcome since coastal lagoons are important and dynamic systems that are likely to be highly influenced by global climate changes.