Endosulfan Transport: I. Integrative Assessment of Airborne and Waterborne Pathways

Abstract

To reduce endosulfan (C9H6O3Cl6S; 6,7,8,9,10,10-hexachloro-1,5, 5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin 3-oxide) contamination in rivers and waterways, it is important to know the relative significances of airborne transport pathways (including spray drift, vapor transport, and dust transport) and waterborne transport pathways (including overland and stream runoff). This work uses an integrated modeling approach to assess the absolute and relative contributions of these pathways to riverine endosulfan concentrations. The modeling framework involves two parts: a set of simple models for each transport pathway, and a model for the physical and chemical processes acting on endosulfan in river water. An averaging process is used to calculate the effects of transport pathways at the regional scale. The results show that spray drift, vapor transport, and runoff are all significant pathways. Dust transport is found to be insignificant. Spray drift and vapor transport both contribute low-level but nearly continuous inputs to the riverine endosulfan load during spraying season in a large cotton (Gossypium hirsutum L.)-growing area, whereas runoff provides occasional but higher inputs. These findings are supported by broad agreement between model predictions and observed typical riverine endosulfan concentrations in two rivers.

Research and practice: environmental action for improving water quality in cotton catchments since 1990

“…Many substantial publications generated from this program eventually appeared in the peer-reviewed literature in 2001 (Connolly et al 2001;Kennedy et al 2001;Kumar and Chapman 2001;Leonard et al 2001;Raupach et al 2001aRaupach et al , 2001bWoods et al 2001) and in a book published by Oxford University Press for the American Chemical Society in 2007 (Schofield et al 2007;Crossan et al 2007;Kennedy et al 2007;Silburn and Kennedy 2007;Simpson 2007). But the periodic reports and workshops conducted as part of the program by the management team enabled serious discussion and the relevance of the research to the industry to be much better understood, publicised more broadly as The Cotton Model (Cox Inall Communications 1998).…”

“…No agrochemical has ever been studied more intensively than endosulfan as in this research program and several of the papers published as a result are outstanding in their quality. For example, the two papers by Raupach et al (2001aRaupach et al ( , 2001b (Figs 3 and 4) dealt with the relative magnitude of the possible mechanisms of endosulfan's transport off sites of applicationas aerial drift, vapour, runoff or on dust. Mathematical models were prepared and validated with intensive data sampling at various distances from sites of application.…”

“…4. Location of endosulfan environmental transport study (Raupach et al 2001a(Raupach et al , 2001b focus area, in the mid and lower reaches of the Namoi River catchment, northern New South Wales, Australia. This study modelled transport of endosulfan aerially as drift and vapour or on dust, or as reabsorption into farm water and by runoff into rivers.…”

Toxicity of endosulfan to Atalophlebia spp. (Ephemeroptera) in the laboratory, mesocosm, and field

“…The off‐field movement of endosulfan may occur via three main routes, i.e., vapor transport, spray drift, and run‐off from land during storm events. Spray drift and vapor transport result in regular but low‐level inputs of endosulfan into the riverine environment [9]. In contrast, runoff provides less frequent but much higher inputs of endosulfan into rivers [9], resulting in elevated endosulfan concentrations that may persist for several days [10,11].…”

Endosulfan Transport: II. Modeling Airborne Dispersal and Deposition by Spray and Vapor

“…This paper is the second of a pair, which have the overall aims of quantifying the magnitude, behavior, and relative importance of each of four major pathways (spray drift, vapor transport, dust transport, and runoff) by which endosulfan can move from farms to rivers, and elucidating management implications. The first paper (Raupach et al, 2001; henceforth Paper I) provides an overview, in which process models and data are combined to assess the contributions of each major transport pathway to riverine endosulfan concentrations. This paper provides modeling details for the airborne pathways.…”