Persistence, degradation, and movement of triclopyr and its ethylene glycol butyl ether ester in a forest soil

Abstract

Triclopyr, [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid, and its ethylene glycol butyl ether ester (EGBE), equivalent to 3.5 mg of the acid, were applied, separately, to the top layers of columns (40 cm X 8.9 cm i.d.) packed with a loam soil or with quartz sand. Water, equivalent to 2.5 cm of precipitation, was leached through each column every second day. After 54 days, residues were found only in the top 10-cm layers of the soils; they were triclopyr and the metabolites 3,5,6-trichloro-2-pyridinol (TP) and 2methoxy-3,5,6-trichloropyridine, accounting for about 5, 85, and 10%, respectively, of the total of the residues which, in turn, was equivalent to 65% of the amount applied initially to the top layers. No residues were detected in the lower soil layers or the eluates. Triclopyr-treated sand: Found were 10 and 65%, respectively, in the sand and the eluates after 54 days. EGBE-treated sand: All residues were in the eluates after only 34 days. All residues from sand and eluates were in the form of triclopyr, except a few eluates from the latter treatment with traces of EGBE or TP.

Best Management Practices for Silvicultural Chemicals and the Science Behind Them

“…Glyphosate is almost immobile in soil and is not thought to move through the soil below 15 cm (EPA, 1993). Triclopyr has been found to move to depths of 10-30 cm (Lee et al, 1985, Stephenson et al, 1990. Hexazinone, perhaps the most studied non-phenoxy forestry herbicide, has been detected at depths down to 75 cm, but more commonly is not detected below about 50 cm (Roy et al, 1989, Feng and Navratil 1990, Allender 1991, Michael et al, 1999.…”

Isolation and characterization of a chlorinated-pyridinol-degrading bacterium

“…3,5,6-Trichloro-2-pyridinol (TCP) has been detected as a major metabolite in environments where the herbicides chlorpyrifos and triclopyr had been applied (3,6,10,12,15,21). TCP is also present in raw wastewater originating from a chlorpyrifos-producing facility.…”

Sensitive voltammetric method for rapid determination of pyridine herbicide triclopyr on bare boron-doped diamond electrode

“…At this point it should be noted that this process is not influenced by the ionization of TCP molecule, taking account on the pK a values of TCP. These are 2.68 [55] for carboxylic group; the pK a value for the TCP pyridinium cation was not found in the literature, nevertheless for structurarly similar chloropyridine derivatives substituted with carboxylic group these are in the range from 3.2 to 4.4 [18], i.e. lower pK a values than the pK a value of pyridinium cation itself (pK a = 5.23).…”