Kinetics and adsorption of metolachlor and atrazine and the conversion products (deethylatrazine, deisopropylatrazine, hydroxyatrazine) in the soil profile of a river basin

Abstract

The adsorption kinetics and adsorption parameters of metolachlor, atrazine, deethylatrazine (DEA), deisopropylatrazine (DIA) and hydroxyatrazine (HA) were investigated in a soil profile in a maize field formed from recent alluvial deposits in a river basin in Greece. We used the batch equilibrium method modified to simulate field conditions as closely as possible for the use and practices related to soil applied pre-emergence herbicides. Pseudo-equilibrium times, determined by kinetic studies, were achieved after 16, 16, 24, 24 and 48 hours for metolachlor, DIA, DEA, HA and atrazine, respectively. At pseudo-equilibrium the percentage of the adsorbed amount increased in the order of DEA (10%) < DIA (14%) < atrazine (27%) < metolachlor (43%) ( HA (94%) which indicates that more than 57% of all compounds except for HA are in solution and available for transport to deeper soil layers when conditions similar to those simulated in the laboratory exist in the field. Adsorption isotherms of all compounds and in most of the cases correlated well with the Freundlich model and adsorption coefficients (K f ) decreased with increased soil depth. Principal component and multiple regression analyses confirmed the importance of the soil organic carbon content on the adsorption capacity of soils for all compounds except HA in the plough layers (0-40 cm). In the subsurface soils (40-110 cm) variables such as clay content and pH were more important. For HA, the K f values determined for the plough and subsurface soil layers were better correlated with clay content and pH. Also in the subsurface soils, the variation in organic carbon content was not correlated with the variation of K f values. Thus calculated K oc-f -values misrepresent the adsorptive capacity of these soils towards the compounds studied.

Evaluation of two pesticide leaching models in an irrigated field cropped with corn

“…The data used was derived from a 0.4 experimental field site in the Ardas River plain (41 37 0 N, 26 21 0 E) in north-eastern Greece and was presented elsewhere in detail (Fragkoulis, 2003;Vryzas et al, 2007;Antonopoulos et al, 2011). Ardas River plain is one of the most important areas nationwide for corn production, and is characterized by warm summers and wet and cold winters, where the average annual rainfall and temperature are 771 mm and 12 C, respectively.…”

Pesticide adsorption in relation to soil properties and soil type distribution in regional scale

“…Metolachlor sorption was measured by Wang et al [21], Singh et al [13], Liu et al [22], Weber et al [23], Vryzas et al [24] and Si et al [25]. Wang et al [21] showed good correlation between the K F coefficient and the OM.…”

“…Tel. : +420 2 24 correlation between the organic carbon content and the K D coefficient) assuming the organic carbon fraction in soil and the organic carbon partition coefficient (K OC ) [3]. However, also other factors may play an important role.…”

Feasibility Assessment of Data-Driven Models in Predicting Pollution Trends of Omerli Lake, Turkey

“…Since dissolved oxygen needs to be related to another set of variables, an ideal tool would be the multiple regression model (MLR; Hutchins et al 2007;Vryzas et al 2007). Multiple linear regression is the most straightforward analysis and is ideal when the relationships are linear; however, the results of this paper show that artificial neural network (ANN) seems to be the ideal model for more precise analysis.…”