我国典型土壤中纳米CuO的老化过程和作物有效性

Copper oxide nanoparticles (CuO NPs) are among the most common and toxic metal oxide nanoparticles. CuO NPs can be released into the soil environment through atmospheric deposition, sewage irrigation, application of biosolids and fertilizer or pesticides. In soil, there exist complex interactions between CuO NPs and soil components, which will change the surface properties and chemical speciation of CuO NPs, thus affect their bioavailability and environmental risks. In this proposal, 15-20 typical soil samples will be selected to represent the soil properties in China. Extended x-ray absorption fine structure, as well as batch experiments, soil incubation experiments and pot experiments are used (1) to systematically investigate the sorption, dissolution, aggregation, aging process and bioavailability of CuO NPs in some typical soils of China, (2) to establish the quantitative model between bioavailable Cu and soil properties such as pH, TOC, clay content and so on, and (3) to explore the action principal and mechanisms of soil properties on the aging and bioavailability of CuO NPs. The main factors that control the aging and bioavailability of CuO NPs will also be determined. This research will provide some basis for the environmental risk evaluation of CuO NPs in soil environment.

纳米CuO（CuO NPs）是最常见的也是毒性较强的金属氧化物纳米材料之一。CuO NPs可通过大气沉降、污水灌溉、污泥及化肥和农药的施用而进入土壤，并与土壤组分发生复杂的相互作用，可能会导致其表面性质及化学形态的改变，从而影响其生物有效性和环境风险。本项目拟选择能够代表我国土壤性质的15-20个典型土壤样品，基于同步辐射技术结合室内批平衡实验、土壤老化培养实验和盆栽实验，系统研究CuO NPs在我国典型土壤中的吸附、溶解、团聚行为及老化过程和作物有效性，建立有效态Cu与土壤性质（pH、CEC、TOC、粘粒含量等）之间的量化模型，探明土壤性质对CuO NPs老化行为和作物有效性的影响规律及机制，确定影响CuO NPs老化和作物有效性的主控因子，为科学评估CuO NPs的环境风险提供理论依据。

系统研究了纳米CuO在我国典型土壤中的吸附、溶解、团聚及老化过程和作物有效性，分别建立了吸附参数、溶解参数与土壤性质之间的量化模型以及沉降和老化动力学模型，揭示了纳米CuO在土壤中的老化规律，确定了影响其有效性的主控因子。主要结果如下：（1）球形纳米氧化铜(CuO NPs)、管状纳米氧化铜(CuO NTs)在土壤中的表观分配系数(KD)均值分别为338−6631 L/kg、1600−19944 L/kg，远高于Cu2+的KD值。CuO NPs的KD值和吸附参数KF值可用土壤pH进行预测，吸附参数N值可用土壤中K、Ca、CaCO3含量进行预测。（2）CuO NPs 在土壤溶液中的Cu2+溶出量为26.6−4194 µg/L，远高于CuO NTs和大颗粒氧化铜(CuO BPs)。CuO NPs的Cu2+溶出量可由pH和溶解性有机碳(DOC)含量进行预测。（3）CuO NPs在土壤溶液中首先和天然胶体发生异质团聚，此后80 nm的CuO仅在江西土壤溶液中有明显的团聚，而50 nm的CuO水合粒径急剧下降然后逐渐稳定。50 nm CuO的沉降速率及残留浓度均高于80 nm CuO。土壤溶液的pH和DOC含量是影响 CuO NPs稳定性的关键因素。（4）CuO NPs处理土壤中DTPA-Cu随老化时间的延长逐渐增加，与Cu(NO3)2处理呈现相反的规律。酸性土壤中，CuO NPs处理的DTPA-Cu 平衡浓度为93.3−98.7 mg/kg，显著高于碱性土壤中 (43.4−56.9 mg/kg)。酸性土壤中，DTPA-Cu平衡浓度顺序为CuO NPs>Cu(NO3)2>CuO BPs，而碱性土壤中为Cu(NO3)2> CuO NPs>CuO BPs。CuO NPs 溶解速率常数和溶解度可由土壤pH及游离铝或无定形铝进行预测。（5）广东红壤(酸性)中，Cu对油菜的生物有效性顺序为CuO NPs>Cu(NO3)2>CuO NTs≈CuO BPs；而河南潮土(碱性)中，顺序为CuO NPs≈Cu(NO3)2>CuO BPs≈CuO NTs。部分CuO NPs以纳米颗粒形式被油菜吸收和转运。上述研究结果为科学评估纳米CuO的环境风险提供了理论依据和数据支撑。