Investigation On Lead Contamination Of Rice Over Fujian Province

A field investigation was conducted over Fujian Province in order to realize Pb contamination of rice grains.118 rice varieties,395 rice samples and the corresponding surface soil samples were collected from 40 counties (or cities, districts) over Fujian Province. Lead concentration in rice grains, total Pb and DTPA-extractable Pb in the soils were determined. The main results were as follows:(1) Total Pb contents of the soils were between 4.70 - 849.6 mg·kg-1, most of which were below the limit for acidic agricultural soil (250 mg·kg-1, pH≤6.5) of Environmental quality standard for soils of China. DTPA-extractable soil Pb varied from 1.81 mg·-kg-1 to 210.0 mg·kg-1,7.1% of which was above the limit for agricultural soil (DTPA-extractable Pb≤28 mg·kg-1) of Standard for heavy-metal pollution classification for agricultural soils in Fujian Province.(2) The average Pb concentration in the grains of each rice varieties was between 0.04 mg·kg-1 and 0.23 mg·kg-1 with the highest Pb concentration being 0.57 mg·kg-1. The Pb content of 23.3% of the grains samples was higher than the limit for rice grains stipulated by Chinese government (0.2 mg·kg-1).(3) The soil-to-grain accumulation factors (CF) based on available soil Pb were between 0.003 and 0.159. Three groups of rice were divided according to their accumulation coefficients:high accumulation variety (CF> 0.05), medium accumulation variety (CF between 0.01 and 0.05), and low accumulation variety (CF< 0.01).(4) The Pb contamination of rice grains was much more serious than that of soil. This situation may be attributed to Pb deposition from atmosphere.