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Fate of Pesticides in the Arid Subtropics, Botswana, Southern Africa

机译：南部非洲博茨瓦纳干旱亚热带地区的农药命运

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摘要

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, atthe southeastern edge of the Okavango Delta, every two weeks for one year. Levels of pesticides in PAS were low, with a-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 a-endosulfan occurred during summer and higher HCB levels occurred in winter. This seasonally 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.
机译：尽管有使用农药的历史，但关于南部非洲空气和土壤中其浓度的数据很少。为了进一步了解控制干旱地区有机污染物命运的过程，对博茨瓦纳空气和土壤中农药的水平，空间趋势和季节变化进行了研究。 2006年5月至2007年5月，XAD树脂基被动空气采样器（PAS）部署在全国15个站点。从9个PAS采样站点附近收集了土壤样本。此外，为期一年，每两周在奥卡万戈三角洲东南边缘的马恩（Maun）收集27个24小时大量空气样本。 PAS中的农药含量低，α-硫丹和林丹含量最高。土壤中的浓度极低，只有有机碳含量高的土壤中才含有大量的狄氏剂和痕量其他农药。特别是，即使过去曾多次向该地区喷洒了滴滴涕和硫丹，但奥卡万戈三角洲的空气和土壤水平却很低。夏季空气中α-硫丹的浓度较高，冬季时HCB浓度较高。这个季节与温度的微小季节变化或雨季或Okavango三角洲的洪水等水文季节事件均无关。因此，观察到的空间和季节模式更可能与农药使用模式有关，而不是与环境因素或历史使用有关。高温和低有机质含量限制了大多数亚热带土壤对农药的吸收能力。没有证据表明吸附到干燥矿物质上起主要作用。因此，亚热带地区的干旱土壤既不是主要的有机污染物库，也不是向大气排放农药的长期重要来源。

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  • 来源
    《Environmental Science & Technology》 |2010年第21期|p.8082-8088|共7页
  • 作者

    CHUBASHINI SHUNTHIRASINGHAM; BAAGI T. MMEREKI; WELLINGTON MASAMBA; CATHERINE E. OYILIAGU; YING D. LEI; FRANK WANIA;

  • 作者单位

    Department of Physical and Environmental Sciences,University of Toronto Scarborough, 1265 Military Trail,Toronto, Ontario, Canada M1C 1A3,Department of Chemistry, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A3;

    rnDepartment of Chemistry, University of Botswana, Gaborone, Botswana;

    rnHarry Oppenheimer Okavango Research Centre, University of Botswana, Maun, Botswana;

    rnDepartment of Physical and Environmental Sciences,University of Toronto Scarborough, 1265 Military Trail,Toronto, Ontario, Canada M1C 1A3;

    rnDepartment of Physical and Environmental Sciences,University of Toronto Scarborough, 1265 Military Trail,Toronto, Ontario, Canada M1C 1A3;

    rnDepartment of Physical and Environmental Sciences,University of Toronto Scarborough, 1265 Military Trail,Toronto, Ontario, Canada M1C 1A3,Department of Chemistry, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A3;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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