Ucisik Ahmed Suheyl, Trapp Stefan
Institute of Environment & Resources, Technical University of Denmark, Bygningstorvet 115, DK-2800 Kgs. Lyngby, Denmark.
Environ Toxicol Chem. 2006 Sep;25(9):2455-60. doi: 10.1897/05-457r.1.
Phenol is an intermediate in the metabolism of plants, but it also is a high-volume production compound frequently found in the environment. The relation between removal, uptake, accumulation, and toxicity of phenol in willow trees (Salix viminalis) was determined. Willows were exposed to phenol levels up to 1000 mg/L in hydroponic solution and sand, respectively. The change on water transpiration of the trees was used to determine toxic effects. In both hydroponic solution and sand, only small inhibition of transpiration was detected up to phenol concentrations of 250 mg/L. For concentrations of 500 mg/L or greater, transpiration fell to 50% or less, and the trees wilted. The trees exposed to 1000 mg/L wilted and eventually died. For initial nominal concentrations of 1000 mg/L, a significantly higher amount of phenol remained at the end of the experiment compared to the amount remaining with all other concentrations. Phenol loss was approximately 90% for the trees that survived, except for trees exposed to the lowest concentration (10 mg/L). The loss of phenol was only 15 to 18% in experiments performed without trees. The results demonstrate a clear relation between removal, accumulation, and toxic effects of phenol in trees. Phenol levels of less than 250 mg/L could be degraded by "in planta" metabolism; therefore, no significant buildup of phenol nor any toxic effects in plants occurred. With higher levels, phenol was still degraded quickly, but an accumulation in trees accompanied by severe toxic effects occurred. Phytoremediation of phenol would be best with concentrations in water or soil solution of less than 250 mg/L, at which the degradation of phenol by willows or associated bacteria is rapid and efficient and the toxic effects on trees are negligible.
苯酚是植物新陈代谢的中间产物，但它也是一种在环境中经常出现的大量生产的化合物。研究了柳树（Salix viminalis）对苯酚的去除、吸收、积累与毒性之间的关系。柳树分别在水培溶液和沙子中暴露于高达1000 mg/L的苯酚水平下。通过树木水分蒸腾的变化来确定毒性效应。在水培溶液和沙子中，苯酚浓度高达250 mg/L时，仅检测到对蒸腾作用的轻微抑制。对于500 mg/L或更高的浓度，蒸腾作用降至50%或更低，树木枯萎。暴露于1000 mg/L的树木枯萎并最终死亡。对于初始标称浓度为1000 mg/L的情况，与所有其他浓度相比，实验结束时残留的苯酚量显著更高。存活的树木中苯酚损失约为90%，但暴露于最低浓度（10 mg/L）的树木除外。在无树木的实验中，苯酚损失仅为15%至18%。结果表明树木对苯酚的去除、积累与毒性效应之间存在明显关系。低于250 mg/L的苯酚水平可通过“植物体内”代谢降解；因此，植物体内没有苯酚的显著积累，也没有任何毒性效应。对于更高的水平，苯酚仍能快速降解，但树木中会出现积累并伴有严重的毒性效应。对于水或土壤溶液中浓度低于250 mg/L的苯酚进行植物修复效果最佳，此时柳树或相关细菌对苯酚的降解迅速且高效，对树木的毒性效应可忽略不计。
