Efficient mitigation of arsenic accumulation in rice seedlings using in situ formed hydrous titanium oxide from aqueous titanyl amendment

Abstract

The Arsenic (As) accumulation problem of plants has to be solved when exploring scattered As micro-polluted water as a new irrigation water source for food production. Herein, efficient As immobilization (1 mg-As/L) was realized by simply adding TiOSO4 (TOS) solution in the irrigation water during rice seedling cultivation. The free soluble As in the rice culture was reduced by 99.4%. Most of the As was enriched in hydrous titanium oxide (HTO) formed from in situ TOS hydrolysis (HTO-TOS), which possessed a very high specific surface area (347.6 m2/g) and the most abundant adsorption-active hydroxyl group. Adding TOS (100 mg/L) is tens of times better than adding TiO2 nanoparticles and is even better than commercial HTO at a dosage up to 1000 mg/L in As-immobilization ability. On the one hand, TOS treatment transformed soluble As to insoluble forms by the strong complexation between freshly formed active HTO and As. On the other hand, a barrier of titanium and iron plaque was formed on root surface. Benefiting from these two aspects, the As contents in rice roots and shoots were reduced by 74.6% and 95.6%, respectively. The TOS treatment strategy had no adverse influence on rice growth while promoted the root growth by 39.4% and alleviated the oxidative stress of rice seedlings. Considering its simple application manner and good As control performance, TOS treatment has great potential on in situ remediation of As-contaminated water and soil during cultivating diverse agricultural plants.