Pesticide retention in the watershed and in a small constructed wetland treating diffuse pollution

Abstract

Loss of pesticides is likely from watersheds where pesticides are used. The herbicides propachlor, linuron and metamitron, and the fungicides propiconazole, fenpropimorph and metribuzin and metalaxyl, were applied on an arable soil plot. A mass balance study showed that approximately 96% of the applied pesticides disappeared within the watershed. Three pesticides remained as residuals in the soil profile one year after the application. The 4% of the pesticides that were lost from the watershed gave peak concentrations, appearing immediately after spraying, reaching levels that can be hazardous to aquatic life. The constructed wetland situated in the first-order stream generally managed to lower the peak concentrations significantly. For the summer season, retention varied from 12 to 67% the first year. The second year, we observed both loss and retention. Increasing the wetland surface from 0.2% to 0.4% of the watershed area increased the average retention with 21% units the first year and 9% units the second year. Chemical properties of the pesticides could explain some of the behaviour in the watershed and in the wetland.

Pesticides in Norwegian Landfill Leachates

“…The aeration/wetland systems also showed more compounds in the treated leachate. The concentration levels in the outlet from the wetlands coincide with those found in previous studies from agricultural areas [11][12][13][14].…”

Mitigation of Agricultural Nonpoint-Source Pesticide Pollution in Artificial Wetland Ecosystems – A Review

“…These systems are more frequently used as they provide better efficiency regarding pesticide dissipation (Braskerud and Haarstad, 2003;Haarstad and Braskerud, 2005;Blankenberg et al, 2006).…”

“…-Efficiency rate is linked to the inlet load of pollutant (Moore et al, 2000;Moore, 2001b;Schulz and Peall, 2001;Paludan et al, 2002). -Wetland efficiency is inversely linked to velocity (Tanner et al, 1995;Dierberg et al, 2002;Haarstad and Braskerud, 2005;Nahlik and Mitsch, 2006;Avsar et al, 2007). -Efficiency depends on the whole system: substrate, vegetation and physicochemical conditions (Braskerud and Haarstad, 2003;Haarstad and Braskerud, 2005;Blankenberg et al, 2006).…”

Physical Parameters of Tropical Wetlands in Lake Victoria Basin: A Case Study of Kigwal/Kimondi, Nyando and Nzoia Wetlands

“…Higher temperatures probably decrease adsorption of hydrocarbons by soil particles and the adsorbed hydrocarbons are released to water. Solubility of hydrocarbons into water is also temperature dependent, thus leading to a decrease in adsorption when temperature rises [19][20][21][22].…”