Relative mobilities of atrazine, five atrazine degradates, metolachlor, and simazine in soils of iowa

Abstract

Abstract-The relative mobilities of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), five atrazine degradates, metolachlor (2-chloro-N-[2-ethyl-5-methylphenyl]-N-[2-methoxy-1-methylethyl]-acetamide), and simazine (2-chloro-4,6-bis-[ethylamino]-s-triazine) were determined in both surface and subsurface soils from five locations in Iowa by soil thin-layer chromatography (STLC). Based on mobility of the compounds, four groups were identified from this study. Deethylatrazine (2-chloro-4-amino-6-isopropylaminos-triazine) was the most mobile compound. The intermediate mobility group included atrazine, deisopropylatrazine (2-chloro-4-ethylamino-6-amino-s-triazine), and didealkylatrazine (2-chloro-4,6-diamino-s-triazine). The less mobile group included metolachlor and simazine, and the nearly immobile group consisted of ammeline (4,6-diamine-s-triazine-2-ol) and hydroxyatrazine (2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine). A clear division between the intermediate and less mobile group was not seen in all soils. Mobilities of all eight compounds in this study were negatively correlated with soil organic matter content (p Յ 0.05) and positively correlated (except for didealkylatrazine) with sand content (p Յ 0.05). The greatest degree of mobility for the compounds studied was seen in Fruitland (sandy) and Nashua (sandy clay loam) subsurface soils, which also had the least organic matter contents. The mobility relationship of atrazine, deethylatrazine, and deisopropylatrazine in this study (deethylatrazine Ն atrazine Ն deisopropylatrazine) is consistent with groundwater monitoring reports. Similar mobilities of atrazine, deisopropylatrazine, and didealkylatrazine in some soils of this study suggest that didealkylatrazine is mobile enough to reach groundwater and therefore should be looked for in routine monitoring.

Fate of Atrazine and Atrazine Degradates in Soils of Iowa

“…Relative mobilities of ATR, DEA, DIA, DDA, and HYA were also assessed in our laboratory by using STLC [10]. Surface and subsurface soils from the five locations in Iowa mentioned previously (Table 1 ) were used in this study.…”

Mass Balance of Metolachlor in a Grassed Phytoremediation System

“…Metolachlor and its metabolites are also slightly mobile in soil (8); in several leaching studies, approximately 1% of applied metolachlor leached through soil columns, while selected metolachlor degradates appeared to be more mobile in soil (9,10).…”

Use of Undisturbed Soil Columns under Controlled Conditions To Study the Fate of [14C]Deethylatrazine

“…Although the relative mobility of DEHYA was not determined in the soil TLC study mentioned (Kruger et al, 1996), it would likely be less mobile than DEA inasmuch as two other hydroxy s-triazine analogues (hydroxyatrazine and ammeline) were less mobile than DEA in that study. Russell et al (1968) indicated that the protonated hydroxy species of s-triazines is bound to clay, which may restrict vertical movement and entrance into groundwater.…”

“…Only a partial displacement of soil water occurs with each addition of rainfall (Thomas and Phillips, 1979). In a study comparing relative mobilities of ATR and degradates using soil TLC (Kruger et al, 1996), DDA and ATR exhibited similar mobilities, and both were significantly less mobile than DEA in this soil type. Therefore, DDA formed in surface or subsurface soils would move through the soil matrix at a slower rate than DEA.…”