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Measured concentrations of herbicides and model predictions of atrazine fate in the Patuxent River estuary.
J Environ Qual. 2004 Mar-Apr; 33(2):594-604.JE

Abstract

The environmental fate of herbicides in estuaries is poorly understood. Estuarine physical transport processes and the episodic nature of herbicide release into surface waters complicate interpretation of water concentration measurements and allocation of sources. Water concentrations of herbicides and two triazine degradation products (CIAT [6-amino-2-chloro-4-isopropylamino-s-triazine] and CEAT [6-amino-2-chloro-4-ethylamino-s-triazine]) were measured in surface water from four sites on 40 d from 4 Apr. through 29 July 19% in the Patuxent River estuary, part of the Chesapeake Bay system. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) was most persistent and present in the highest concentrations (maximum = 1.29 microg/L). Metolachlor [2-chloro-6'-ethyl-N-(2-methoxy-1-methylethyl)-o-acetoluidide], CIAT, CEAT, and simazine (1-chloro-3,5-bisethylamino-2,4,6-triazine) were frequently detected with maximum concentration values of 0.61, 1.1, 0.76, and 0.49 microg/L, respectively. A physical transport model was used to interpret atrazine concentrations in the context of estuarine water transport, giving estimates of in situ degradation rates and total transport. The estimated half-life of atrazine in the turbid, shallow upper estuary was t(1/2) = 20 d, but was much longer (t(1/2) = 100 d) in the deeper lower estuary. Although most (93%) atrazine entered the estuary upstream via the river, simulations suggested additional inputs directly to the lower estuary. The total atrazine load to the estuary from 5 April to 15 July was 71 kg with 48% loss by degradation and 31% exported to the Chesapeake Bay. Atrazine persistence in the estuary is directly related to river flows into the estuary. Low flows will increase atrazine residence time in the upper estuary and increase degradation losses.

Authors+Show Affiliations

USDA-ARS, Environmental Quality Laboratory, Building 007, Room 225, Beltsville, MD 20705, USA. mcconnel@ba.ars.usda.govNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

15074811

Citation

McConnell, Laura L., et al. "Measured Concentrations of Herbicides and Model Predictions of Atrazine Fate in the Patuxent River Estuary." Journal of Environmental Quality, vol. 33, no. 2, 2004, pp. 594-604.
McConnell LL, Harman-Fetcho JA, Hagy JD. Measured concentrations of herbicides and model predictions of atrazine fate in the Patuxent River estuary. J Environ Qual. 2004;33(2):594-604.
McConnell, L. L., Harman-Fetcho, J. A., & Hagy, J. D. (2004). Measured concentrations of herbicides and model predictions of atrazine fate in the Patuxent River estuary. Journal of Environmental Quality, 33(2), 594-604.
McConnell LL, Harman-Fetcho JA, Hagy JD. Measured Concentrations of Herbicides and Model Predictions of Atrazine Fate in the Patuxent River Estuary. J Environ Qual. 2004 Mar-Apr;33(2):594-604. PubMed PMID: 15074811.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Measured concentrations of herbicides and model predictions of atrazine fate in the Patuxent River estuary. AU - McConnell,Laura L, AU - Harman-Fetcho,Jennifer A, AU - Hagy,James D,3rd PY - 2004/4/13/pubmed PY - 2004/6/16/medline PY - 2004/4/13/entrez SP - 594 EP - 604 JF - Journal of environmental quality JO - J Environ Qual VL - 33 IS - 2 N2 - The environmental fate of herbicides in estuaries is poorly understood. Estuarine physical transport processes and the episodic nature of herbicide release into surface waters complicate interpretation of water concentration measurements and allocation of sources. Water concentrations of herbicides and two triazine degradation products (CIAT [6-amino-2-chloro-4-isopropylamino-s-triazine] and CEAT [6-amino-2-chloro-4-ethylamino-s-triazine]) were measured in surface water from four sites on 40 d from 4 Apr. through 29 July 19% in the Patuxent River estuary, part of the Chesapeake Bay system. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) was most persistent and present in the highest concentrations (maximum = 1.29 microg/L). Metolachlor [2-chloro-6'-ethyl-N-(2-methoxy-1-methylethyl)-o-acetoluidide], CIAT, CEAT, and simazine (1-chloro-3,5-bisethylamino-2,4,6-triazine) were frequently detected with maximum concentration values of 0.61, 1.1, 0.76, and 0.49 microg/L, respectively. A physical transport model was used to interpret atrazine concentrations in the context of estuarine water transport, giving estimates of in situ degradation rates and total transport. The estimated half-life of atrazine in the turbid, shallow upper estuary was t(1/2) = 20 d, but was much longer (t(1/2) = 100 d) in the deeper lower estuary. Although most (93%) atrazine entered the estuary upstream via the river, simulations suggested additional inputs directly to the lower estuary. The total atrazine load to the estuary from 5 April to 15 July was 71 kg with 48% loss by degradation and 31% exported to the Chesapeake Bay. Atrazine persistence in the estuary is directly related to river flows into the estuary. Low flows will increase atrazine residence time in the upper estuary and increase degradation losses. SN - 0047-2425 UR - https://www.unboundmedicine.com/medline/citation/15074811/Measured_concentrations_of_herbicides_and_model_predictions_of_atrazine_fate_in_the_Patuxent_River_estuary_ DB - PRIME DP - Unbound Medicine ER -