Strand Stuart E, Dossett Michael, Harris Chad, Wang Xiaoping, Doty Sharon L
College of Forest Resources, University of Washington, Seattle, Washington 98195, USA.
Z Naturforsch C J Biosci. 2005 Mar-Apr;60(3-4):325-30.
In field-scale mass balance studies of poplar remediation of carbon tetrachloride (CT), more than 95% of the mass of CT was degraded with all of the CT chlorine accountable as chloride ion accumulation in the soil. Atmospheric loss of CT through leaf transpiration and trunk diffusion was insignificant. These findings are consistent with previously reported uptake and degradation of trichloroethylene (TCE) by poplar. Poplar phytoremediation of CT and TCE results in little decrease in aqueous concentration, since water is taken up at about the same rate as the chlorinated compounds. From this result we predict that phytoirrigation--the application of pumped contaminated groundwater to planted systems--will result in concentrations of the pollutants at the bottom of the root zone that are higher than permitted regulatory levels. Such plantations will be susceptible to loss of contaminants during rainfall events, possibly resulting in pollution of uncontaminated soil. Greenhouse studies of pollutant profiles in the media beneath poplar trees that were surface irrigated with TCE and CT confirmed that regulatory concentrations of these pollutants were not achieved in the root zone of the poplar; rather concentrations fell by less than 50%.
在杨树修复四氯化碳（CT）的田间尺度质量平衡研究中，超过95%的CT质量被降解，所有CT中的氯都以氯离子积累的形式存在于土壤中。通过叶片蒸腾和树干扩散造成的CT大气损失微不足道。这些发现与先前报道的杨树对三氯乙烯（TCE）的吸收和降解情况一致。杨树对CT和TCE的植物修复导致水相浓度几乎没有降低，因为水的吸收速率与氯化化合物的吸收速率大致相同。根据这一结果，我们预测植物灌溉——将抽取的受污染地下水应用于种植系统——将导致根区底部的污染物浓度高于监管允许水平。这样的种植园在降雨期间容易造成污染物流失，可能导致未受污染土壤受到污染。对用TCE和CT进行表面灌溉的杨树下方介质中污染物分布的温室研究证实，杨树的根区并未达到这些污染物的监管浓度；相反，浓度下降不到50%。
