Melamine has received increasing public attention as a persistent, mobile and toxic (PMT) substance. To better assess environmental exposure and risks of melamine and related triazines (cyromazine, ammeline, and atrazine), a new passive sampling method based on the diffusive gradients in thin films (DGT) technique has been developed and validated in this study. The studied triazines were adsorbed quickly and strongly by the selected mixed cation exchange (MCX) binding gels. This MCX-DGT can linearly accumulate these chemicals over at least 5 days, with neither significant individual influence from pH (6–8), ionic strength (0.01–0.5 M) or dissolved organic matter (0–10 M), or interaction effects. Field applications in Southern China showed that DGT performed well in both sewage treatment plant (STP) and river samples. Melamine was found to be the dominant triazine with the concentrations at μg·L⁻¹ in the STP and receiving river. Surprisingly, much higher concentration of melanine was found in the STP effluent than influent, and appeared to be some of the highest concentrations reported in STPs worldwide to date. Comparable melamine and atrazine concentraions in the STP effluent and receiving river suggested other sources to the river. The MCX-DGT sampler developed here was demonstrated to be reliable and robust for measuring the triazines in waters, and is promising as an in situ tool in understanding the occurrence, sources, and fate of the emerging PMT substances in aquatic environment.

三聚氰胺作为一种持久性、流动性和有毒 (PMT) 物质越来越受到公众的关注。为了更好地评估三聚氰胺和相关三嗪（环丙氨嗪、苯胺和阿特拉津）的环境暴露和风险，本研究开发并验证了一种基于薄膜扩散梯度 (DGT) 技术的新型被动采样方法。所研究的三嗪被选定的混合阳离子交换 (MCX) 结合凝胶快速而强烈地吸附。这种 MCX-DGT 可以在至少 5 天内线性积累这些化学物质，不受 pH (6–8)、离子强度 (0.01–0.5 M) 或溶解有机物 (0–10 M) 或相互作用影响的显着个体影响. 在华南地区的现场应用表明，DGT 在污水处理厂 (STP) 和河流样品中均表现良好。^-1在 STP 和接收河中。令人惊讶的是，在 STP 流出物中发现的黑色素浓度比流入物中高得多，并且似乎是迄今为止全球 STP 中报告的最高浓度之一。STP 出水和接收河中的三聚氰胺和莠去津浓度相当，表明该河还有其他来源。此处开发的 MCX-DGT 采样器被证明在测量水中三嗪方面是可靠和稳健的，并且有望作为了解水生环境中新兴 PMT 物质的发生、来源和归宿的原位工具。