[Effects of phosphorus-containing substances on arsenic uptake by rice]

The disodium hydrogen phosphate (DSP) and hydroxyapatite (HAP) were added into arsenic contaminated soil, then rice pot experiment was conducted to study the effects of phosphorus (P)-containing substances on arsenic (As) uptake by rice. The results showed that: DSP and HAP significantly increased soil pH and the contents of available P in soil (P < 0.05), activating soil arsenic. And DSP was stronger than HAP in improving the migration ability of As in soil. DSP and HAP treatments both significantly reduced the contents of total As in root, as well as total As and inorganic As in brown rice. But HAP significantly increased total As contents in stem. DSP and HAP treatments had better reducing effects on inorganic As than on total As in brown rice. And DSP had the same reducing effects as HAP on total As and inorganic As in brown rice. Analysis results showed that the contents of As in rice were affected by the antagonism between P and As and the increase of As bio-availability in soil. The antagonism played the major role in this study and it was clearly exhibited in both root and rice. Lower dosage (< or = 0.12 g x kg(-1)) of DSP and HAP increased total biomass of rice and brown rice yield, but with the increase of P addition, the two kinds of P-containing substances obviously inhibited the growth of rice, and inhibition by HAP was relatively light.