Department of Environmental Science and Technology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Saitama-city, Saitama 338-8570, Japan; Department of Zoology and Environmental Management, Faculty of Science, University of Kelaniya, Kelaniya 11600, Sri Lanka E-mail:
Department of Environmental Science and Technology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Saitama-city, Saitama 338-8570, Japan.
Water Sci Technol. 2023 Jun;87(12):3095-3107. doi: 10.2166/wst.2023.177.
The study of the modulation of the toxicity of heavy metals by coexisting chemicals in the environment is vital for realistic ecological risk assessment. Our study was aimed at determining possible toxicity modulations of Cd by humic acid (HA) using the Allium cepa test system. A. cepa bulbs were exposed to Cd (1 and 5 mg/L) and HA (10 mg/L) individually or in mixtures. The root lengths of the bulbs and cytogenetic endpoints in root meristematic cells, including the mitotic index (MI), nuclear abnormalities (NAs), and chromosomal abnormalities (CAs), were determined. The results revealed that the MIs of A. cepa co-exposed to HA and Cd were significantly recovered by >15% compared with those of A. cepa subjected to Cd-only treatments, and this response was more sensitive than the phytotoxic response (root length). Furthermore, the burden of NAs was significantly decreased in the co-exposed bulbs by >20% compared with bulbs with Cd-only treatments. The frequencies of CAs were also reduced in the bulbs co-exposed to HA and 1 and 5 mg/L Cd by >15 and >25%, respectively, compared with bulbs receiving Cd-only treatments. Therefore, our findings indicated that HA plays a significant protective role in Cd toxicity in A. cepa.
研究环境中共存化学物质对重金属毒性的调节作用对于现实的生态风险评估至关重要。本研究旨在使用洋葱根尖细胞试验系统，确定腐殖酸（HA）对 Cd 可能产生的毒性调节作用。将洋葱鳞茎分别暴露于 Cd（1 和 5mg/L）和 HA（10mg/L）中，或同时暴露于两者中。测定了鳞茎的根长和根尖分生细胞的细胞遗传学终点，包括有丝分裂指数（MI）、核异常（NAs）和染色体异常（CAs）。结果表明，与单独暴露于 Cd 的洋葱相比，同时暴露于 HA 和 Cd 的洋葱的 MI 恢复了超过 15%，其响应比植物毒性响应（根长）更为敏感。此外，与单独暴露于 Cd 的洋葱相比，同时暴露于 HA 和 1 和 5mg/L Cd 的洋葱中的 NAs 负担减少了超过 20%。同时暴露于 HA 和 1 和 5mg/L Cd 的洋葱中的 CAs 频率也分别减少了超过 15%和 25%。因此，我们的研究结果表明，HA 在 Cd 对洋葱根尖的毒性中具有重要的保护作用。
