| The statistical characteristics of plant uptake factor (PUF) of As,Cd and Pb for rice/wheat cereal were analyzed and summarized based on collected data in China. The data were selected and distinguished between field investigation and glasshouse experiment in which metal salts were added to clean soils as grown media. Results showed that the PUF median and range of As,Cd and Pb for rice cereal were 0.026 (0.004-0.090),0.150 (0.014-1.470),0.005 (0.001-0.031) and 0.010 (0.003-0.033),0.360 (0.056-1.700),0.002 (0.001-0.019) for field investigation and salt added experiment respectively. The PUF median and range of As,Cd and Pb for wheat cereal were 0.010 (0.001-0.110),0.190 (0.030-2.110),0.017(0.001-0.075) and 0.010 (0.003-0.028),0.150 (0.055-0.730),0.001 (0.001-0.014) for field investigation and salt added experiment respectively. Significant PUF distribution differences were found between field investigation and salt added experiment. PUF provided not exactly predictive ability of metal uptake by crops since the PUF values were influenced by a variety of factors including the soil contamination levels,basic soils characteristics,the cultivation of the crops and other environmental conditions. However,the ln(PUF) followed Gaussian distribution (R2=0.38-0.94) which is useful for general risk assessment and soil benchmark derivation of contaminated croplands. Use of these statistical models is restricted to the range of data they have been derived,as extrapolation outside this range is often unreliable. Soil properties and surrounding environment of the crops should also be in accordance with the conditions PUF derived. |
