Air-soil exchange of organochlorine pesticides in agricultural soils. 1. Field measurements using a novel in situ sampling device
Air-soil exchange of organochlorine pesticides in agricultural soils. 1. Field measurements using a novel in situ sampling device
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DOI：
10.1021/es020540r
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发表时间：
2003-04-01
影响因子：
11.4
通讯作者：
Harner, T
中科院分区：
文献类型：
--
作者：
Meijer, SN;Shoeib, M;Harner, T
本文介绍了在两种受污染的农业土壤中对一系列有机氯（OC）农药的土壤-空气分配进行原位测量的初步结果。在安大略省南部以集约化农业闻名的两个地区，烟草带和荷兰沼泽，进行了一项土壤调查，并利用该调查确定了几种有机碳农药的高水平。实验在每个地区的一个场地进行，使用圆盘状采样器对非常接近土壤表面的空气进行采样。通过将土壤的手性特征与装置采集的空气中的手性特征和周围空气中的手性特征进行比较，测试了采样空气的平衡状态。虽然结果表明，采样器下空气中104%的反式氯丹（TC）和顺式氯丹（CC）分别来自土壤，但这些结果的传播误差（TC的SO为34%，CC的SO为26%）太大，无法提供平衡的确凿证据。因此，本文用土壤-空气商（Q(SA)）代替土壤-空气分配系数（K-SA）。这个值是“真实”K-SA的近似值。结果表明，109 QSA与log K-OA呈线性关系，符合K- sa = 0.411rhophi(OC)K（OA）的关系式，其中rho为土壤密度（kg L-1）。利用这一关系，计算了空气和土壤的流失率。这一计算结果确定了一个强烈的差异，有利于土壤到空气的转移。这一梯度是通过在不同高度对其中一个区域的测量得到证实的。土壤-空气交换是有机有机农药整体命运的关键过程。这项研究的结果将提高我们模拟这一过程的能力，并解释土壤之间的差异。
Initial results are presented for in situ measurements of soil-air partitioning for a range of organochlorine (OC) pesticides in two contaminated agricultural soils. A soil survey was conducted and used to identify high levels of several OC pesticides in two regions of southern Ontario that are known for their intensive agriculture, the Tobacco Belt and the Holland Marsh. Experiments were conducted at one field in each region by sampling air very close to the soil surface using a disc-shaped sampler. The equilibrium status of the sampled air was tested by comparing the chiral signature of the soil with the signature in air sampled by the device and ambient air. Although results showed that 104% of trans-chlordane (TC) and 96% of cis-chlordane (CC) in the air under the sampler originated from the soil, the propagated errors in these results (34% SO for TC and 26% SO for CC) are too large to provide conclusive evidence for equilibrium. Therefore, a soil-air quotient (Q(SA)) is reported here instead of the soil-air partition coefficient (K-SA). This value is an approximation of the "true" K-SA. Results show a linear relationship between 109 QSA and log K-OA and fit in with the relationship K-SA = 0.411rhophi(OC)K(OA) where rho is the soil density (kg L-1). Using this relationship, fugacities were calculated in air and soil. Results of this calculation identify a strong disparity that favors soil-to-air transfer. This gradient is confirmed by measurements at different heights over one of the fields. Soil-air exchange is a key process in the overall fate of OC pesticides. The results from this study will improve our ability to model this process and account for differences between soils.