Untreated hexamethylenetetramine (HMT) was discharged into the Tone River in the central area of Japan, and the risk management plan in the watershed area has been strengthened because HMT is the precursor of formaldehyde (FA) regulated by Japanese water supply law. The release of HMT could occur not only in steady but also in unsteady environmental conditions. In this context, no quantitative environmental risk assessments have dealt with the combined events of FA precursor outflow and natural disasters, such as a massive tsunami attack. In this study, we estimated the time course changes of HMT concentrations at the near water treatment plant (WTP) intakes due to tsunami run-up in the river after HMT discharge from facilities along the river during a massive tsunami attack, then potential ecological and health impacts were estimated. This method has a strong analytical ability to reveal the relationship between wave source and inland water run-up in consideration of 3D density flow. For ecological risk, the half maximal effective concentration (EC₅₀) was employed. We found that HMT concentration would not reach a level of concern even after the accident. For potential health risk in terms of the possible maximum inlet concentration of HMT at the WTP, the FA formation amount was 5.3 × 10⁻² mg/L, which was below the water quality standard.

中文翻译：

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大规模海啸袭击期间六亚甲基四胺向淀河释放的环境风险预测性案例研究

未经处理的六亚甲基四胺（HMT）被排放到日本中部地区的Tone河中，由于HMT是日本供水法规定的甲醛（FA）的前体，因此分水岭地区的风险管理计划得到了加强。HMT的释放不仅可以在稳定的环境条件下发生，而且可以在不稳定的环境条件下发生。在这种情况下，没有进行定量的环境风险评估来处理FA前体外流和自然灾害（例如大规模海啸袭击）的综合事件。在这项研究中，我们估计了在大规模海啸袭击期间，沿河设施排放HMT后，由于河中海啸加剧，近水处理厂（WTP）入口处HMT浓度随时间的变化。估计对健康的影响。考虑到3D密度流，该方法具有很强的分析能力，可以揭示波源与内陆水流上升之间的关系。对于生态风险，最大有效浓度的一半（EC₅₀）被雇用。我们发现，即使在事故发生后，HMT浓度也不会达到令人关注的水平。就潜在的健康风险而言，WTP处HMT的最大入口浓度可能是因为，FA的形成量为5.3×10 ^-2 mg / L，低于水质标准。