Occurrence, uptake, and health risk assessment of nonylphenol in soil-celery system simulating long-term reclaimed water irrigation.

Reclaimed water (RW) irrigation provides an effective method to alleviate freshwater resources shortage. However, the residual endocrine disrupting chemicals in RW may cause potential risks to the environment and human body. Pot experiments were conducted to study the occurrence and environmental behavior of nonylphenol (NP) in soil-celery system simulating long-term RW irrigation, and exposure to NP was assessed to identify human health risks. Celery was grown on soil with different initial NP concentrations (0.126-22.9 mg·kg-1) to simulate the different irrigation years. After harvest, the NP concentrations in roots, stems and leaves were 0.26-1.51, 0.21-0.45 and 0.33-0.74 mg·kg-1, respectively. The NP concentrations in soil at depths of 5, 10 and 15 cm were 0.047-1.75, 0.088-1.77 and 0.048-1.07 mg·kg-1, respectively. The results showed a limited NP enrichment capacity of celery and low residual rates of NP in soil-celery system, which were between 6.33% and 26.3%. Both the bioconcentration factors (BCFs) and the residual rates of NP decreased with the initial NP concentrations in soil. The total noncancer hazard quotients (HQs) for human exposure to NP from celery and soil had the order of 10-4-10-3, which was lower than the acceptable risk level of 1 and showed safe conditions under long-term RW irrigation.