Passive air sampling of organochlorine pesticides in Mexico.
The spatial and temporal variation of organochlorine pesticides (OCs) in air across Mexico was investigated by deploying passive samplers at eleven stations across the country during 2005-2006. Integrated samples were taken over three-month periods and quantified for DDT compounds, endosulfans, toxaphenes, components of technical chlordane, hexachlorocyclohexanes (HCHs), and dieldrin. Enantiomers of chiral chlordanes and o,p'-DDT were determined on chiral stationary phase columns as an indicator of source and age. Results are discussed in combination with pumped air samples taken at four other stations in southern Mexico during 2002-2004. DDT and its metabolites, endosulfan and toxaphene were the most abundant OCs detected in all sampling sites. Atmospheric concentrations of SigmaDDT (p,p'-DDT + o,p'-DDT + p,p'-DDE + o,p'-DDE + p,p'-DDD + o,p'-DDD) ranged from 15 to 2360 pg m(-3) with the highest concentrations found in southern Mexico and the lowest found in northern and central Mexico. A fresher DDT residue was observed at sites with greater DDT use and in the southern part of the country, as shown from the higher FDDTe = p,p'-DDT/(p,p'-DDT + p,p'-DDE) and nearly racemic o,p'-DDT. This agrees with the former heavy use of DDT in the endemic malarious area of the country. A local hotspot of endosulfan was identified at an agricultural area in Mazatlan, Sinaloa, with a annual mean concentration of SigmaENDO (endosulfans I + II + endosulfan sulfate) = 26,800 pg m(-3). At this site, higher concentrations of SigmaENDO were recorded during the winter (November to February) and spring (February to May) periods. From back trajectory analysis, this coincides with a shift in the air mass coming from the Pacific Ocean (May to November) to the inland agricultural area (November to May). The elevated SigmaENDO observed is likely due to the local agricultural usage. HCHs, chlordanes, transnonachlors, and dieldrin were more evenly distributed across the country likely due to them being aged residues and more diffuse in the environment. In contrast, hotspots of endosulfans, DDTs, and toxaphenes were observed as they were heavily used in localized agricultural or malarious regions of Mexico.
Wong
Fiona
F
Centre for Atmospheric Research Experiments, Science and Technology Branch, Environment Canada, 6248 Eighth Line, Egbert, ON, Canada.
Alegria
Henry A
HA
Bidleman
Terry F
TF
Alvarado
Víctor
V
Angeles
Felipe
F
Galarza
Alfredo Avila
AA
Bandala
Erick R
ER
Hinojosa
Idolina de la Cerda
Ide L
Estrada
Ignacio Galindo
IG
Reyes
Guillermo Galindo
GG
Gold-Bouchot
Gerardo
G
Zamora
Jose Vinicio Macías
JV
Murguía-González
Joaquín
J
Espinoza
Elias Ramirez
ER
D000393:Air Pollutants / Q000032:analysis*; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D008800:Mexico; D010575:Pesticides / Q000032:analysis*; D012621:Seasons
D000393:Air Pollutants; D006843:Hydrocarbons, Chlorinated; D010575:Pesticides