Effect of soil-applied fertilizers on arsenic transport and transformation mechanisms in the water-soil-rice system

Arsenic (As) pollution in paddy field appeared around the world， however， the study on the effect of fertilizer on As accumulation in water-soil-rice system remains unknown. This study investigated the effects of organic fertilizer (OF)， inorganic fertilizer (IOF)， and bio-organic fertilizer (BOF) on As transformation in water-soil-rice system under surface water (SW) and high-As groundwater (GW) irrigation conditions through potting experiments. The results indicated that IOF group had the lowest As in rice grain (0.34 mg/kg)， followed closely by BOF (0.36 mg/kg) and OF (0.43 mg/kg) under SW irrigation. Under SW irrigation， the lowest reduction in iron mineral dissolution and the lowest pore water As concentration were observed in the IOF group， which reduced the accumulation in rice grain. The BOF application resulted in the highest As content in the rice root but the transformation in rice was lowest， resulting in the lowest As content in the straw. High-As GW irrigation increased both the total and bioavailable As in the soil， and increased As absorption by rice， causing the As levels in rice grains to exceed the standard (GB2762-2017). According to the values of bioconcentration factor (BCF) and translocation factor (TF)， the IOF helped reduce As accumulation in rice under SW irrigation， whereas the OF effectively reduced As accumulation in rice grain under high-As GW irrigation. This study provides a theoretical basis and technical support for the prevention and control of As contamination of rice.