A concentration retrieving method using statistics is presented, which is applied in differential optical absorption spectroscopy (DOAS) for measuring the concentration of SO2. The method uses the standard deviation of the differential absorption to represents the gas concentration. Principle component analysis (PCA) method is used to process the differential absorption spectrum. In the method, the basis data for the concentration retrieval of SO2 is the combination of the PCA processing result, the correlation coefficient, and the standard deviation of the differential absorption. The method is applied to a continuous emission monitoring system (CEMS) with optical path length of 0.3 m. Its measuring range for SO2 concentration is 0-5 800 mg x m(-3). The nonlinear calibration and the temperature compensation for the system were executed. The full scale error of the retrieving concentration is less than 0.7% FS. And the measuring result is -4.54 mg x m(-3) when the concentration of SO2 is zero.

经调查,山东诸城烟区土壤含氮量稍微偏高,土壤速效磷、速效钾比较丰富,有机质较低,氯含量较高.经过3年土壤改良和采取减氮施肥措施后,土壤速效氮明显降低,速效磷、速效钾有所增加,尤其土壤有机质含量呈增高趋势,氯离子含量微有降低.调查数据说明,改良土壤措施可行,对烟草植株的生长发育、营养供应和烟叶香气的提高均起到了良好的促进作用.尽管土壤速效钾含量较丰富,但有效性较低,还应多施钾肥,适当补充锌肥.