Fate and transport of chlormequat in subsurface environments

• Published in: Environmental science and pollution research international 2010-07, Vol.17 (6), p.1245-1256
• Main Authors: Juhler, René K, Henriksen, Trine, Rosenbom, Annette E, Kjaer, Jeanne
• Format: Article
• Language: English
• Subjects: Adsorption; Aquatic environment; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bioavailability; CCC; Chloride; chlormequat; Chlormequat - analysis; Chlormequat - chemistry; Chlormequat - metabolism; Chlorocholine chloride; Clay; Climate change; Climatic conditions; Contaminated sediments; Contamination; Cycocel; Desorption; Drainage; Drainage water; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental impact; Environmental Monitoring; Environmental risk; Fertility; Fresh Water - chemistry; Freundlich isotherm; Geology; Groundwater; Growth regulators; Kinetics; Laboratories; Leaching; Membrane permeability; Moisture content; Permeability; Pesticides; Plant growth; Plant Growth Regulators - analysis; Plant Growth Regulators - chemistry; Plant Growth Regulators - metabolism; Pollution; Pore water; Precipitation; quaternary ammonium herbicides; Research Article; Sandy soils; soil; Soil adsorption; Soil fertility; Soil Pollutants - analysis; Soil Pollutants - chemistry; Soil Pollutants - metabolism; Soil pollution; Soil types; Soil water; Soils; Sorption; Studies; Surface water; Surface-groundwater relations; Vadose water; Waste Water Technology; Water analysis; Water balance; Water flow; Water Management; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Water Pollution Control; Water sampling
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-010-0303-5

Background, aim and scope Chlormequat (Cq) is a plant growth regulator used throughout the world. Despite indications of possible effects of Cq on mammalian health and fertility, little is known about its fate and transport in subsurface environments. The aim of this study was to determine the fate of Cq in three Danish subsurface environments, in particular with respect to retardation of Cq in the A and B horizons and the risk of leaching to the aquatic environment. The study combines laboratory fate studies of Cq sorption and dissipation with field scale monitoring of the concentration of Cq in the subsurface environment, including artificial drains. Materials and methods For the laboratory studies, soil was sampled from the A and B horizons at three Danish field research stations—two clayey till sites and one coarse sandy site. Adsorption and desorption were described by means of the distribution coefficient (K d) and the Freundlich adsorption coefficient (K F,ads). The dissipation rate was estimated using soil sampled from the A horizon at the three sites. Half life (DT₅₀) was calculated by approximation to first-order kinetics. A total of 282 water samples were collected at the sites under the field monitoring study— groundwater from shallow monitoring screens located 1.5-4.5 m b.g.s. at all three sites as well as drainage water from the two clayey sites and porewater from suction cups at the sandy site, in both cases from 1 m b.g.s. The samples were analysed using LC-MS/MS. The field monitoring study was supported by hydrological modelling, which provided an overall water balance and a description of soil water dynamics in the vadose zone. Results The DT₅₀ of Cq from the A horizon ranged from 21 to 61 days. The Cq concentration-dependant distribution coefficient (K d) ranged from 2 to 566 cm³/g (median 18 cm³/g), and was lowest in the sandy soil (both the A and B horizons). The K F,ads ranged from 3 to 23 (µg¹ ⁻ ¹/n (cm³)¹/n g⁻¹) with the exponent (1/n) ranging from 0.44 to 0.87, and was lowest in the soil from the sandy site. Desorption of Cq was very low for the soil types investigated (