作为近年来备受关注的新型碳纳米材料，氧化石墨烯(GO)已逐渐被广泛应用到人类的生产生活中。随着GO的生产使用量不断增长，在生产、储存、运输、使用及回收处理的过程中，GO纳米颗粒不可避免的会通过多种途径进入到土壤-地下水系统中，对生态环境及人类健康造成潜在的污染风险。本文以GO纳米颗粒为主要研究对象，通过室内实验及数值模拟的研究方法，系统考察多孔介质理化性质(粒径、成分、含水率、非均质性等)及水化学因素(离子强度(IS)及类型、pH、腐殖酸(HA)等)协同影响下GO在多孔介质中的运移行为。主要研究结论如下： 1.介质粒径影响GO在一维(1-D)饱和及非饱和均质石英砂多孔介质中的运移行为。饱和均质石英砂多孔介质中，1 mM NaCl IS条件下GO运移能力较高，介质粒径变化对GO运移影响较小，穿透率均高于92.5%。20mM NaCl IS条件下GO运移能力较低，介质粒径变化则对其运移影响较大，随着多孔介质粒径降低，GO的穿透率由43.6%下降到0%。非饱和均质石英砂多孔介质中，GO在多孔介质中运移能力与饱和条件下相比较低，且两种IS条件下介质粒径变化均对GO运移有较大影响。随着多孔介质粒径的降低，1 mM NaCl IS条件下GO的穿透率由91.1%下降到60.4%；20mM NaCl IS条件下GO的穿透率由36.1%降低到0.0%。 2.介质成分对GO运移具有较大影响，GO在1-D饱和均质灰岩介质中运移能力与石英砂介质中相比较低。电解质类型及浓度、pH、HA等水化学因素对GO在灰岩介质中运移影响较大。GO在灰岩介质中的运移随着溶液IS的升高而降低，随着IS由0.1mM NaCl上升至10.0mM NaCl，GO的穿透率从65.2%下降至7.8%。与Cl-相比，溶液中S²⁻的存在提高了GO在灰岩介质中的运移能力， 0.15mM和1.5mM Na₂S IS条件下，GO的穿透率为73.5%和57.0%。灰岩介质中溶液的pH变化对GO运移影响较小，随着溶液pH由9.5下降至4.5，GO的穿透率由51.7%下降至40.3%。溶液中HA的存在显著增强了 GO在灰岩介质中的运移，随着溶液中HA的浓度由0㎎ L⁻¹上升至5㎎ L⁻¹， GO在灰岩介质中的穿透率由45.4%上升至92.7%。 3.多孔介质非均质性显著影响GO的运移及释放，优势流主导GO在1-D饱和及非饱和非均质多孔介质中的运移及释放过程。饱和条件下，粗砂区为非均质结构中的快流区，细砂区为慢流区，1mM NaCl IS条件下，GO运移能力较高(穿透率均高于90.0%)，其在快流区与慢流区均有穿透；20mM IS条件下，GO运移能力降低(穿透率低于57.2%)，且仅在快流区有穿透。非饱和条件下，细砂区含水率较高而成为快流区，粗砂区含水率极低成为慢流区，两种IS条件下(1mM及20mM NaCl)几乎全部的GO都通过快流区穿透。运移过程中沉积在多孔介质中的GO能在溶液IS降低的条件下被释放，且非饱和条件下GO的释放量与饱和条件下相比较低，表明除了溶液IS条件，可能存在其他因素影响GO在非饱和非均质石英砂多孔介质中的沉积及释放。 4.GO在饱和二维(2-D)多孔介质中的运移行为与1-D介质中有所不同。饱和2-D多孔介质中，GO颗粒能在横向弥散作用下沿垂直水流方向运移，密度差对其污染羽运移影响不大。饱和2-D非均质多孔介质中，GO在粗砂区随优势流快速运移。随着溶液IS的升高及介质粒径的降低，GO在2-D均质多孔介质中的穿透率由99.1%下降至45.1%，非均质多孔介质中的穿透率由86.4%下降至51.3%，且环境条件不变时，GO在石英砂表面的沉积过程不可逆。部分运移过程中(20mM IS条件下)沉积的GO能在溶液IS降低条件下瞬时释放。非均质条件下，释放的GO运移过程受非均质介质中优势流影响。 5.根据GO运移实验结果，建立相应的沉积动力学模型对GO运移行为进行模拟。模型能较好模拟GO在多孔介质中的运移行为，模型结果与实验结果具有较高拟合度。 本文系统研究了不同环境因素下地下水系统中GO的运移及沉积行为，研究结果有助于深入了解GO在地下水系统中的环境行为，为准确预测及评估地下水系统中GO的环境风险提供科学依据，具有重要的潜在应用价值。 关键词：氧化石墨烯；纳米颗粒；运移；多孔介质；介质粒径；非均质；含水率；石英砂；灰岩；腐殖酸；离子强度；pH

 As a high-profile carbon nanomaterial, graphene oxide (GO) has been widely used in human life and industry. With the rapidly increasing applications and production, GO will unavoidably be released into the soil and groundwater systems through various pathways, causing the potential pollution risk for environment. In this study, experiments and numerical models were conducted for understanding the transport behaviors of GO nanoparticles in porous media under various media physicochemical properties (e.g. sand grain size, chemical composition, moisture and heterogeneity) and aquatic chemistry conditions (e.g. ionic strength (IS) or type, pH and humic acid). The main conclusion for this research are as follows: 1.Sand grain size had a strong influence on the transport and retention of GO in one-dimensional (1-D) saturated and unsaturated quartz sand porous media. Under saturated conditions, GO had high mobility at 1 mM NaCl IS condition with the mass recovery higher than 92.5%, and the variety of sand grain size barely influenced the transport behavior of GO. When the solution IS was 20 mM NaCl, GO mobility was reduced and decreased with the grain size, which mass recovery was ranged from 43.6% to 0.0%. Under unsaturated conditions, GO mobility was lower than that in saturated porous media, and sand grain size variety had an important influence on GO transport at both 1 mM and 20 mM NaCl. With the grain size reduction, the mass recovery of GO were decreased from 91.1% to 60.4% and 36.1% to 0.0% at 1 and 20 mM NaCl separately. 2.The media chemical composition greatly affect GO transport. Compared with quartz sand, GO mobility in 1-D limestone media was limited and influenced by several aquatic chemistry conditions such as electrolyte type and concentration, pH and HA concentration. Transport of GO was decreased with the increasing solution IS in limestone media. With the IS condition increased from 0.1 to 10.0 Mm NaCl, the mass recovery of GO reduced from 65.2% to 7.8%. Compared with Cl⁻, the presence of S²⁻ promoted GO transport in limestone media, the mass recovery of GO were 73.5%o and 57.0% at the IS conditions of 0.15 and 1.5 mM Na₂S separately. Solution pH showed slight effect on the transport of GO in limestone with the mass recovery range from 40.3% to 51.7%. GO mobility was enhanced with the presence of HA, the mass recovery of GO increased from 45.4% to 92.1% with the HA concentration increased from 0 ㎎ L⁻¹ to 5 ㎎ L⁻¹. 3.The structural heterogeneity significantly influence the transport and retention of GO in 1-D saturated and unsaturated porous media. GO retention and transport in 1-D heterogeneous porous media was dominated by the preferential flow phenomena. Under saturated conditions, the coarse sand with higher hydraulic conductivity was the fast flow domain, and the fine sand was the slow flow domain. At 1 mM NaCl IS condition, GO mobility was high (mass recovery higher than 90.0%) and delivered from both fast and slow flow domain. At 20 mM NaCl IS condition, GO mobility was reduced (mass recovery lower than 57.2%) and only delivered from fast flow domain. Under unsaturated conditions, fine sand with higher moisture content became the fast flow domain, and the coarse sand was the slow flow domain. Almost all of GO delivered from fast flow domain at both 1 and 20 mM NaCl IS conditions. The previous retained GO particles could be released by reducing solution IS, and the released amount of GO was lower under unsaturated conditions than saturated conditions. This result indicated that in addition to IS conditions, other mechanisms might contribute to the retention and release of GO in structured heterogeneous porous media under unsaturated conditions. 4.Transport behavior of GO in saturated two-dimensional (2-D) porous media showed something different from that in 1-D porous media. GO can be transported vertically through dispersion in 2-D porous media without vertical flows, and the density had negligible influence on its transport. In 2-D heterogenous porous media, GO moved fastly in coarse sand following with the preferential flow. GO transport decreased with the increasing solution IS and decreasing sand grain size, with the mass recovery ranged from 99.1% to 45.1% in 2-D homogeneous porous media, and 86.4% to 51.3% in 2-D heterogenous porous media. The retention of GO under higher IS condition (20 mM NaCl) was irreversible when the experimental conditions were unchanged. Some of the previous retained GO particles could be instantaneously released with the reducing solution IS, and the released process of GO in 2-D heterogenous porous media was influenced by preferential flow. 5.Based on the experimental data, various of kinetic deposition models were well applied to describe the transport and retention of GO in porous media, and model simulations fitted the observed experimental data very well. This work systematically studied the fate and transport of GO in the groundwater system. This research may contribute to the detailed understanding of GO environmental behavior in the groundwater system, and provide scientific basis for the accurate prediction and assessment of GO environmental risk in the groundwater systems, having an important potential application value. Keywords: Grahene Oxide; Nanoparticles; Transport; Porous Media; Grain Size; Heterogeneity; Moisture; Quartz Sand; Limestone; Humic Acid; Ionic Strength; pH