Robinson Brett, Greven Marc, Green Steve, Sivakumaran Siva, Davidson Peter, Clothier Brent
HortResearch, Private Bag 11 030, Palmerston North, New Zealand.
Sci Total Environ. 2006 Jul 1;364(1-3):113-23. doi: 10.1016/j.scitotenv.2005.07.012. Epub 2005 Sep 16.
There have been conflicting reports as to the extent that copper-chromium-arsenic (CCA) treatments leach from timber. In New Zealand, vineyards utilise CCA-treated posts at a rate of 579 posts per hectare. This represents a potential CCA burden on the soil of 12, 21, and 17 kg/ha, respectively, for the three elements. Given a replacement rate of 4% per year, the use of CCA-treated posts may result in an accumulation of these elements in the soil, possibly leading to groundwater contamination. We undertook a general survey to determine the extent of CCA leaching from treated vineyard posts. Treated Pinus radiata posts were sampled at six sites around the Marlborough region of New Zealand to represent a range of post ages and soil types. For each post, above- and belowground wood samples were taken. As well, the soil adjacent to the post was sampled at a 50 mm horizontal and 100 mm vertical distances from the post. The belowground wood samples of the posts had significantly lower CCA concentrations than the aboveground portions, which were not significantly different from new posts. This indicates leaching. Soils surrounding the posts had significantly higher CCA concentrations than control soils. Higher CCA concentrations were measured under the posts than laterally. Some 25% of the samples exceeded 100 mg/kg As, the Australian National Environment Protection Council (ANEPC) guideline level for As in agricultural soil, and 10% exceeded 100 mg/kg Cr, the ANEPC limit for chromium. At one site, we found a significant positive correlation between post age and CCA-leaching. The CCA issue could be eliminated by using alternative posts, such as steel, concrete, or untreated woods such as Eucalyptus or beech. Alternatively, CCA-treated posts could, for example, be lacquered or otherwise protected, to reduce the rate of CCA leaching.
关于铜铬砷（CCA）处理剂从木材中沥出的程度，一直存在相互矛盾的报道。在新西兰，葡萄园每公顷使用579根经CCA处理的木桩。这分别意味着三种元素在土壤中的潜在CCA负担为每公顷12千克、21千克和17千克。考虑到每年4%的更换率，使用经CCA处理的木桩可能会导致这些元素在土壤中积累，进而可能导致地下水污染。我们进行了一项全面调查，以确定经处理的葡萄园木桩中CCA的沥出程度。在新西兰马尔堡地区周围的六个地点采集了经处理的辐射松木桩样本，以代表不同的木桩使用年限和土壤类型。对于每根木桩，采集了地上和地下的木材样本。此外，在距离木桩水平50毫米和垂直100毫米处采集了相邻土壤样本。木桩的地下木材样本中的CCA浓度明显低于地上部分，地上部分与新木桩的CCA浓度没有显著差异。这表明存在沥出现象。木桩周围土壤中的CCA浓度明显高于对照土壤。在木桩下方测得的CCA浓度高于侧面。约25%的样本中砷含量超过100毫克/千克，这是澳大利亚国家环境保护委员会（ANEPC）规定的农业土壤中砷的指导水平，10%的样本中铬含量超过100毫克/千克，这是ANEPC规定的铬的限量。在一个地点，我们发现木桩使用年限与CCA沥出之间存在显著的正相关关系。可以通过使用替代木桩，如钢铁、混凝土或未经处理的木材（如桉树或山毛榉）来消除CCA问题。或者，例如，可以对经CCA处理的木桩进行涂漆或以其他方式保护，以降低CCA的沥出率。
