Gensemer R W, Dixon D G, Greenberg B M
Department of Biology, University of Waterloo, Ontario, Canada.
Ecotoxicol Environ Saf. 1998 Jan;39(1):57-64. doi: 10.1006/eesa.1997.1606.
The ability of a commercial (Aldrich Chemical Co.) humic acid (AHA) to ameliorate the photo-induced toxicity of polycyclic aromatic hydrocarbons (PAHs) was examined using Lemna gibba L. (G3). Plants were exposed to anthracene and benzo(a)pyrene both with and without AHA and grown under visible light as well as lighting that simulates relative abundances of UV-A and UV-B in natural sunlight (SSR). Modest additions of 1.6 mg.L-1 AHA were sufficient to ameliorate the photo-induced toxicity of 2 mg.L-1 anthracene by improving growth rates to nearly 50% of controls and inducing minor recovery from complete chlorosis in the most highly affected plants. Benzo(a)pyrene induced minor, but significant, chlorosis under SSR, and AHA additions always increased growth rate and chlorophyll content, although to less of a degree than anthracene toxicity under SSR. The protective effects of AHA on anthracene toxicity increased linearly with increases in AHA concentrations up to 6.2 mg.L-1. Slopes of these relationships changed in the presence of UV light relative to visible light treatments; thus UV changed the extent to which AHA mediates PAH toxicity. However, the net effect was still for AHA to ameliorate PAH photo-induced toxicity even though UV has the potential to photooxidize AHA and enhance the production of potentially toxic reactive oxygen species from AHA photosensitization.
使用浮萍（Lemna gibba L. (G3)）研究了市售（奥德里奇化学公司）腐殖酸（AHA）改善多环芳烃（PAH）光诱导毒性的能力。植物分别在有和没有AHA的情况下暴露于蒽和苯并(a)芘，并在可见光以及模拟自然阳光中UV-A和UV-B相对丰度的光照（SSR）下生长。适度添加1.6 mg.L-1的AHA足以改善2 mg.L-1蒽的光诱导毒性，使生长速率提高到对照的近50%，并使受影响最严重的植物从完全失绿中稍有恢复。在SSR条件下，苯并(a)芘诱导了轻微但显著的失绿现象，添加AHA总能提高生长速率和叶绿素含量，尽管程度低于SSR条件下蒽的毒性。AHA对蒽毒性的保护作用随AHA浓度增加至6.2 mg.L-1呈线性增加。相对于可见光处理，在紫外光存在下这些关系的斜率发生了变化；因此，紫外线改变了AHA介导PAH毒性的程度。然而，即使紫外线有可能使AHA光氧化并增强AHA光敏化产生潜在有毒的活性氧物种，但总体效果仍然是AHA改善了PAH的光诱导毒性。
