Safe utilization of arsenic-contaminated soil promoted by drip irrigation and chitosan aerogel: A case study in a...

Arsenic contamination of soil poses a serious threat to ecological systems. Because phytoremediation is often inefficient, facilitating the safe utilisation of contaminated agricultural land is increasingly important. In this study, a polyacrylic acid/chitosan composite aerogel (PAA/CA) was combined with an agronomic regime comprising drip irrigation and the intercropping of Brassica rapa L. ssp. chinensis and Zea mays L. to facilitate safe crop production and localised arsenic interception. PAA/CA exhibited a sheath-core biphasic structure, high arsenic adsorption capacity and strong hydrophilicity. The pot experiment showed that localised leaching under drip irrigation drove arsenic migration from the near-drip zone occupied by B. rapa L. ssp. chinensis towards the more distant Z. mays L. zone. Strategically placed, highly hydrophilic PAA/CA intercepted this water-driven arsenic flux. Compared with flood irrigation (T4), drip irrigation combined with aerogel application (T1) reduced arsenic accumulation in the edible parts of B. rapa L. ssp. chinensis by 36% and increased arsenic retention in the Z. mays L. root zone by 58%. Furthermore, the physical disintegration of the aerogel over time suggested its potential environmental compatibility. These findings provide proof of concept for the safe utilisation of arsenic-contaminated soil through synergy between microscale material barriers and macroscale hydraulic redistribution.