Omil Beatriz, Piñeiro Verónica, Merino Agustín
Department of Soil Science and Agricultural Chemistry, Escuela Politécnica Superior, University of Santiago de Compostela, E-27002 Lugo, Spain.
Sci Total Environ. 2007 Aug 1;381(1-3):157-68. doi: 10.1016/j.scitotenv.2007.04.004. Epub 2007 May 11.
Wood ash, a by-product generated in power plants, can be used to fertilize forest plantations to replenish nutrients lost during harvesting. Although wood ash generally contains low levels of trace metals, release of some of these may occur soon after ash application in acid soils. The risk of heavy metal contamination associated with application of mixed wood ash was assessed in six Pinus radiata D. Don plantations, on two types of mineral soil differing in texture, drainage and CECe. Four of the stands received a single application of 4500 kg ha(-1) (March 2003), and in the other two stands the same treatment was applied over three consecutive years (2003-2005). Trace metal (Cd, Cr, Cu, Mn, Ni, Pb, Zn) concentrations were monitored throughout the 3 years in different components of the forest ecosystem--soil solid fraction, soil solution, tree needles, ground vegetation and different mushroom species. Repeated applications of wood ash led to moderate increases in soil extractable Mn and Zn, and Mn in all mushrooms species. However, the maximum concentrations did not reach levels potentially harmful to organisms. Concentrations of Zn, Cu and Cd decreased in some mushroom species, probably because of increased soil pH caused by the treatment. Heavy metal concentrations in tree needles and ground vegetation were not altered. Although the risk of heavy metal contamination appears to be low, the long-term effects of wood ash application must be assessed.
木灰是发电厂产生的一种副产品，可用于给人工林施肥，以补充采伐过程中流失的养分。虽然木灰通常含有低水平的痕量金属，但在酸性土壤中施用木灰后，其中一些痕量金属可能很快就会释放出来。在六个辐射松人工林中，对两种质地、排水和有效阳离子交换量不同的矿质土壤上施用混合木灰相关的重金属污染风险进行了评估。其中四个林分单次施用4500千克/公顷（2003年3月），另外两个林分在连续三年（2003 - 2005年）进行相同处理。在3年期间，对森林生态系统的不同组分——土壤固相部分、土壤溶液、树叶、地面植被和不同蘑菇种类，监测了痕量金属（镉、铬、铜、锰、镍、铅、锌）的浓度。重复施用木灰导致土壤中可提取的锰和锌以及所有蘑菇种类中的锰适度增加。然而，最大浓度未达到对生物体可能有害的水平。某些蘑菇种类中锌、铜和镉的浓度下降，可能是由于处理导致土壤pH值升高。树叶和地面植被中的重金属浓度未改变。虽然重金属污染风险似乎较低，但必须评估施用木灰的长期影响。
