State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
Environ Pollut. 2019 Dec;255(Pt 1):113177. doi: 10.1016/j.envpol.2019.113177. Epub 2019 Sep 5.
The transport and retention of nanoplastics (NP, 200 nm nanopolystyrene) functionalized with surface carboxyl (NPC), sulfonic (NPS), low-density amino (negatively charged, NPA), and high-density amino (positively charged, NPA) groups in seawater-saturated sand with/without humic acid were examined to explore the role of NP surface functionalities. The mass percentages of NP recovered from the effluent (M) with a salinity of 35 practical salinity units (PSU) were ranked as follows: NPC (19.69%) > NPS (16.37%) > NPA (13.33%) > NPA (9.78%). The homoaggregation of NPS and NPA was observed in seawater. The transport of NPA exhibited a ripening phenomenon (i.e., a decrease in the transport rate with time) due to the high attraction of NP with previously deposited NP, whereas monodispersed NPA presented a low M value because of the electrostatic attraction between NPA and negatively charged sand. Retention experiments showed that the majority of NPC, NPS and NPA accumulated in a monolayer on the sand surface, whereas NPA accumulated in multiple layers. Suwannee River humic acid (SRHA) could remarkably improve the transportability of NPC, NPS, and NPA by increasing steric repulsion. The strong attraction between NPA and the deposited NPA in the presence of SRHA triggered the weak ripening phenomenon. As seawater salinity decreased from 35 PSU to 3.5 PSU, the increase in electrostatic repulsion of NP-NP and NP-sand enhanced the transport of NPC, NPS, and NPA, and the ripening of NPA breakthrough curves disappeared. In deionized water, NPC, NPS, and NPA achieved complete column breakthrough because the electrostatic repulsion between NP and sand intensified. However, the M values of NPA in 3.5 PSU seawater and deionized water presented limited increments of 15.49% and 23.67%, respectively. These results indicated that the fate of NP in sandy marine environments were strongly affected by NP surface functionalities, seawater salinity, and coexisting SRHA.
用功能化纳米塑料（NP，200nm 纳米聚苯乙烯）研究了在有/无腐殖酸的海水饱和砂中，NP 表面功能化对其传输和保留的影响。NP 表面功能化包括表面羧基（NPC）、磺酸基（NPS）、低浓度氨基（带负电荷，NPA）和高浓度氨基（带正电荷，NPA）。NP 从 35 个实用盐度单位（PSU）海水中的流出物（M）中的质量百分比如下：NPC（19.69%）>NPS（16.37%）>NPA（13.33%）>NPA（9.78%）。在海水中观察到 NPS 和 NPA 的同聚集体。NPA 的传输表现出老化现象（即随着时间的推移传输速率降低），这是由于 NP 与先前沉积的 NP 之间的高吸引力所致，而单分散 NPA 由于 NP 与带负电荷的砂之间的静电吸引力，M 值较低。保留实验表明，大多数 NPC、NPS 和 NPA 以单层形式积累在砂表面上，而 NPA 则以多层形式积累。苏万尼河腐殖酸（SRHA）可以通过增加空间排斥作用显著提高 NPC、NPS 和 NPA 的传输性。在 SRHA 的存在下，NPA 与先前沉积的 NPA 之间的强烈吸引力触发了较弱的老化现象。当海水盐度从 35 PSU 降低至 3.5 PSU 时，NP-NP 和 NP-砂之间的静电斥力增加，促进了 NPC、NPS 和 NPA 的传输，NPA 突破曲线的老化现象消失。在去离子水中，由于 NP 与砂之间的静电斥力增强，NPC、NPS 和 NPA 完全达到柱突破。然而，NPA 在 3.5 PSU 海水中和去离子水中的 M 值分别仅增加了 15.49%和 23.67%。这些结果表明，NP 在沙质海洋环境中的命运受到 NP 表面功能、海水盐度和共存 SRHA 的强烈影响。
