Fate of pesticides in the arid subtropics, Botswana, Southern Africa.
Journal article
Authors / Editors
Research Areas
No matching items found.
Publication Details
Author list: Shunthirasingham C, Mmereki BT, Masamba W, Oyiliagu CE, Lei YD, Wania F
Publisher: American Chemical Society
Publication year: 2010
Journal: Environmental Science and Technology (0013-936X)
Journal acronym: Environ Sci Technol
Volume number: 44
Issue number: 21
Start page: 8082
End page: 8
Number of pages: -8073
ISSN: 0013-936X
eISSN: 1520-5851
Languages: English-Great Britain (EN-GB)
Abstract
Despite a history of pesticide usage, few data exist on their concentrations in air and soil of Southern Africa. To add to the understanding of the processes controlling the fate of organic contaminants in arid regions, the levels, spatial trends, and seasonal variability of pesticides were studied in air and soil from Botswana. XAD resin-based passive air samplers (PAS) were deployed at 15 sites across the country from May 2006 to May 2007. Soil samples were collected from the vicinity of nine of the PAS sampling sites. In addition, 27 24-h high-volume air samples were collected in Maun, at the southeastern edge of the Okavango Delta, every two weeks for one year. Levels of pesticides in PAS were low, with α-endosulfan and lindane being most abundant. Concentrations in soils were extremely low and only soils with high organic carbon contained notable amounts of dieldrin and traces of other pesticides. In particular, air and soil from the Okavango Delta had very low levels even though the area had repeatedly been sprayed with DDT and endosulfan in the past. Air samples from Eastern Botswana, where the majority of the population lives, contained higher levels. Higher air concentrations of α-endosulfan occurred during summer and higher HCB levels occurred in winter. This seasonality was related with neither minor seasonal changes in temperature nor hydrological seasonal events such as the rainy season or the flooding of the Okavango Delta. Thus, the observed spatial and seasonal patterns are more likely related to pesticide usage pattern than to environmental factors or historical use. High temperature and low organic matter content limit the uptake capacity of most subtropical soils for pesticides. No evidence was found that sorption to dry mineral matter plays a major role. Arid soils in subtropical regions are therefore neither a major reservoir of organic contaminants nor do they constitute a significant long-term source of pesticides to the atmosphere.
Keywords
No matching items found.
Documents
No matching items found.
