国际标准中木质包装热处理最低温度的判定

目的]解决WTO《SPS协议》下植物检疫措施ISPM 15标准中热处理指标判定科学性的问题,避免因判定产生的误区导致该标准在执行过程中处理结果无效,降低有害生物疫情传播的风险.方法]设计了不同采样点样本温度试验,运用标准SN/T2371-2009中提及的美国森林产品实验室Simpson等人的预测模型理论公式,对木质包装堆放的样本内部温度分布进行理论推导,探讨样木内部温度分布对温度判定的影响、木质包装的堆放对最低温度判定的影响、窑体内温度场对温度判定的影响.结果]提出了一种科学判定标准中最低温度的方法和原则,即具有代表性的样木温度判定位置只需要控制在中心点附近即可,但建议将判定温度提高5％;最低温度的判定样木的厚度不是与最厚的木质包装一致,而是应该选择整窑包装中堆放紧密的总厚度最大值作为样本（如样本厚度是5 cm时,使用木材中心温度记录仪6 em样木;若样本厚度是6 cm,使用木材中心温度记录仪8 cm样木）;样木的位置需要根据窑体实测温度场的情况选择低温点放置;所有的影响因素中样木的厚度对温度判定的影响最大.结论]在这个原则和方法下,样木的指示温度可以作为整批处理对象是否符合国际标准的判定依据.

Judgment of Minimum Temperature in Heat Treatment of Wood Packaging in International Standards

Objective] To improve the scientificity of heat treatment judgement indicators mentioned in ISPM15 standard,avoid invalid execution results and reduce the risk of pest outbreak.Method] Temperature experiments were conducted in various sample plots,using prediction model theory formula provided by Simpson from USA Forest Products Laboratory mentioned in SN/T2371-2009,theoretical derivation was conducted on inner temperature of wood packaging stacking.Effects of inner temperature,wood packaging stacking and temperature field on judgement of temperature were discussed.Result] A scientific method and principle for judging minimum temperature was proposed,namely representative judgement position should be fixed around the central point,it was suggested that the judgement temperature should be improved by 5％ ; width of sample wood is not consistancy with the thickest wood packaging（for example,when wood width is 5 cm,wood center temperature recorder is 6 cm ; when wood width is 6 cm,temperature recorder is 8 cm） ; minimum temperature position for sample wood was selected according to measured temperature field; wood width has the most significant influence to temperature judgement.Conclusion] Under this principle and method,the indicated temperature of sample wood can be used as judgment evidence of whether the whole batch of objects are in accordance with international standards.