Kong Yu, Li Xiaona, Tao Mengna, Cao Xuesong, Wang Zhenyu, Xing Baoshan
Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
J Hazard Mater. 2023 Oct 5;459:132071. doi: 10.1016/j.jhazmat.2023.132071. Epub 2023 Jul 17.
Multiple water-chemistry factors determine nanoplastics aggregation and thus change their bioavailability and ecological risks in natural aquatic environments. However, the dominant factors and their interactive mechanisms remain elusive. In this study, polystyrene nanoplastics (PSNPs) showed greater colloidal stability in Li Lake water compared to ultrapure water. The RDA and PARAFAC results suggested that dissolved organic carbon, humic acid (HA) in particular, Ca, and pH are critical factors influencing PSNPs aggregation. Batch experiments showed that the critical coagulation concentration (CCC) of PSNPs was increased with pH increase; HA increased the CCC of PSNPs in NaCl by 2.6-fold but decreased that in CaCl by 1.8-fold. Moreover, cations increased the adsorption of HA on PSNPs. The DFT results suggested that HA-cations complexes (E = -1.10 eV and -0.51 eV for HA-Ca and HA-Na, respectively) but not HA alone (E = -0.33 eV) are the main scenarios for their adsorption on PSNPs, and a cation-π mechanism between PSNPs and HA-cations complexes dominates PSNPs aggregation in this scenario. The findings are significant for better understanding the environmental process and fate of nanoplastics in aquatic environments. ENVIRONMENTAL IMPLICATION: Nanoplastics are kinds of emerging contaminants. Nanoplastic aggregation determines their bioavailability and toxic risks to ecological health. Herein, the hydrodynamic sizes of PSNPs in local Li Lake water was tested and a redundancy analysis was performed to examine the key water-chemistry factors driving PSNPs aggregation. Moreover, the mechanisms in PSNPs aggregation driven by multiple dominant water-chemistry factors including cations, pH, and DOC were firstly unveiled by combining experimental characterization and theoretical computations. This work improves our understanding of the environmental fate of nanoplastics and provides a theoretical basis for the risk assessment and control of nanoplastics in real aquatic environments.
多种水化学因素决定了纳米塑料的聚集，从而改变了它们在天然水生环境中的生物可利用性和生态风险。然而，主导因素及其相互作用机制仍然不明。在本研究中，与超纯水相比，聚苯乙烯纳米塑料（PSNPs）在蠡湖水中表现出更高的胶体稳定性。冗余分析（RDA）和平行因子分析（PARAFAC）结果表明，溶解有机碳，特别是腐殖酸（HA）、钙和pH值是影响PSNPs聚集的关键因素。批次实验表明，PSNPs的临界聚沉浓度（CCC）随pH值升高而增加；HA使PSNPs在NaCl中的CCC增加了2.6倍，但在CaCl中降低了1.8倍。此外，阳离子增加了HA在PSNPs上的吸附。密度泛函理论（DFT）结果表明，HA-阳离子络合物（HA-Ca和HA-Na的E分别为-1.10 eV和-0.51 eV）而非单独的HA（E = -0.33 eV）是其吸附在PSNPs上的主要情况，并且在这种情况下，PSNPs与HA-阳离子络合物之间的阳离子-π机制主导PSNPs的聚集。这些发现对于更好地理解纳米塑料在水生环境中的环境过程和归宿具有重要意义。环境意义：纳米塑料是一类新兴污染物。纳米塑料的聚集决定了它们的生物可利用性以及对生态健康的毒性风险。在此，测试了当地蠡湖水中PSNPs的流体动力学尺寸，并进行了冗余分析以检查驱动PSNPs聚集的关键水化学因素。此外，首次通过结合实验表征和理论计算揭示了由阳离子、pH值和溶解性有机碳等多种主要水化学因素驱动PSNPs聚集的机制。这项工作增进了我们对纳米塑料环境归宿的理解，并为实际水生环境中纳米塑料的风险评估和控制提供了理论依据。
