【作者】 杨华；

【导师】 杨刚； 钟贵江；

【作者基本信息】 四川农业大学 ， 资源与环境硕士（专业学位）， 2025， 硕士

【摘要】 土壤镉（Cd）污染因其高毒性和生物累积性严重威胁农业生态安全,而微塑料（PS-MPs）作为新型污染物可通过载体效应提高Cd的生物有效性,加剧Cd的毒理效应。然而,现有研究多聚焦单一污染物毒性效应,对MPs-Cd复合体系的Cd积累转运特征、及其对水稻的复合毒性与叶面阻控相关机理仍缺乏系统研究。因此,本研究选择水稻作为研究对象,通过盆栽试验,系统探究不同浓度PS-MPs与Cd单一及复合污染对土壤特性、水稻生长生理及Cd累积转运的影响,通过解析复合污染效应机制,揭示污染物交互作用对水稻的毒性效应。基于毒性试验结果,采用叶面喷施Si-NPs阻控剂的干预策略,系统研究不同施用浓度和时期对上述指标的调控效应,阐明Si-NPs对水稻生长生理和Cd累积转运的调控机理。研究结果如下:（1）PS-MPs与Cd污染提高了土壤碱解氮和有效磷含量,有机质和速效钾含量无显著变化。PS-MPs与Cd抑制了水稻根系对土壤养分的吸收,抑制了水稻生长产量及光合作用,提高了水稻体内MDA含量和抗氧化酶（SOD/CAT/POD）活性,诱导氧化应激反应,导致光和生理受损。单一污染时,PS-MPs与Cd诱导的胁迫影响随其浓度增加而增强;复合污染时,PS-MPs与Cd形成协同毒理效应,加剧了对水稻的毒害。高浓度的PS-MPs与Cd复合处理下水稻株高、地上鲜重和净光合速率分别较对照处理显著降低了15.7%、12.8%和29.6%（P<0.05）,受损最为严重。PS-MPs与Cd污染还抑制了矿质元素在水稻体内的积累和迁移,使地上部分矿质元素含量降低,影响了籽粒品质。（2）PS-MPs与Cd污染降低了土壤p H和残渣态Cd占比,增强了土壤Cd的迁移毒性,促进了水稻根部对土壤Cd的吸收。PS-MPs与Cd污染促进了Cd由根部到籽粒的迁移积累;在Cd污染土壤上,PS-MPs促进了Cd的迁移积累,形成了协同效应。高浓度的PS-MPs与Cd复合处理使得BCF_{植株/土壤}、TF_{地上/地下}、TF_籽粒/叶和TF_籽粒/壳分别较对照处理显著提高了426.2%、93.9%、94.6%和114.0%（P<0.05）,由于PS-MPs具有载体效应,籽粒Cd大量积累,威胁粮食安全。（3）叶面喷施Si-NPs降低了土壤有机质、碱解氮与有效磷含量,促进了水稻根系养分的吸收,提高了水稻生长产量及光合速率,缓解了PS-MPs与Cd胁迫导致的氧化损伤,使MDA含量和抗氧化酶（SOD/CAT/POD）活性下调。抽穗期单施1500 mg·L^-1Si-NPs处理效果最佳,使株高、地上鲜重和净光合速率分别较对照组显著提高了14.3%、8.6%和70.3%（P<0.05）。此外,Si-NPs促进了水稻各部位矿质元素的积累,促进了水稻的生理生化活动,尤其提高了籽粒矿质元素含量,对籽粒的营养价值有重要意义。（4）叶面喷施Si-NPs提高了土壤p H和残渣态Cd含量与占比,降低了土壤Cd的迁移毒性,抑制了水稻根部对土壤Cd的吸收;叶面喷施Si-NPs将Cd以草酸态大量富集在叶片里,抑制了Cd从叶片到籽粒的再分配。抽穗期单施1500mg·L^-1Si-NPs处理为最佳处理,其BCF_{植株/土壤}、TF_籽粒/叶和TF_籽粒/壳分别较对照处理显著降低了41.5%、71.7%和36.4%（P<0.05）,TF_叶/茎提高了113.4%。综上所述,本研究系统探讨了不同浓度PS-MPs与Cd单一及复合污染对土壤理化性质、水稻生长产量及生理生化指标的影响,明确了不同浓度PS-MPs与Cd单一及复合污染下土壤-水稻系统Cd的积累、转运与赋存相关特征;系统探明了PS-MPs与Cd复合污染下叶面喷施Si-NPs对土壤理化性质、水稻生长产量及生理生化指标的影响,阐明了叶面喷施Si-NPs对土壤-水稻系统Cd积累、转运及赋存的影响及潜在机理。更多还原

【Abstract】 Soil cadmium（Cd）pollution is a serious threat to agro-ecological safety due to its high toxicity and bioaccumulation,while microplastics（PS-MPs）as a new type of pollutants can increase the biological toxicity of Cd through the carrier effect and exacerbate the toxicological effects of Cd.However,most of the existing studies focused on the toxic effects of single pollutants,and there is still a lack of systematic research on the Cd accumulation and transport characteristics of the MPs-Cd composite system,as well as its composite toxicity and foliar blocking and controlling mechanism on rice.Therefore,in this study,we chose rice as the research object,and systematically investigated the effects of single and composite pollutants of different concentrations of PS-MPs and Cd on soil properties,growth and physiology of rice,and Cd accumulation and transportation through potting experiments,so as to analyze the mechanism of composite pollutant effects and to reveal the toxicity of pollutant interactions on rice.Based on the results of the toxicity test,the intervention strategy of foliar spraying of Si-NPs blocker was adopted to systematically study the regulatory effects of different application concentrations and periods on the above indexes,and to elucidate the regulatory mechanism of Si-NPs on the growth and physiology of rice and the accumulation and transportation of Cd.The results of the study are as follows:（1）PS-MPs and Cd pollution increased soil alkaline dissolved nitrogen（AN）and effective phosphorus（EP）content,while organic matter（OM）and fast-acting potassium（FAK）content did not change significantly.PS-MPs and Cd inhibited the absorption of soil nutrients by rice roots,suppressed the growth and yield of rice,inhibited photosynthesis,and increased the content of MDA and the activity of antioxidant enzymes（SOD/CAT/POD）,induced oxidative stress,and resulted in the impairment of Light and physiology.physiological functions were impaired.The stress effects induced by PS-MPs and Cd were enhanced with the increase of their concentrations in single contamination;in compound contamination,PS-MPs and Cd formed a synergistic toxicological effect,which exacerbated the toxicity to rice.Rice plant height,aboveground fresh weight,and net photosynthetic rate were significantly reduced by 15.7%,12.8%,and 29.6%,respectively（P<0.05）under the high concentration of PS-MPs and Cd composite treatment compared with the control treatment,which was the most severely damaged.PS-MPs and Cd contamination also inhibited the accumulation and migration of mineral elements in the rice body,which reduced the content of mineral elements in aboveground parts,and affected the quality of the seed grain.（2）PS-MPs with Cd pollution decreased soil p H and residue state Cd percentage,enhanced soil Cd transport toxicity,and promoted the uptake of soil Cd by rice roots.PS-MPs with Cd pollution promoted the transport accumulation of Cd from roots to seeds;on Cd-contaminated soils,PS-MPs facilitated the transport accumulation of Cd,creating a synergistic effect.The high concentration of PS-MPs and Cd composite treatment resulted in a significant increase of 426.2%,93.9%,94.6%and 114.0%（P<0.05）in BCF_plant/soil,TF_{aboveground/underground},TF_seed/leafand TF _seed/hull,respectively,compared with the control treatment,which threatened food security due to the large accumulation of Cd in the seeds as a result of the carrier effect of PS-MPs.（3）Foliar spraying of Si-NPs reduced soil organic matter,alkaline dissolved nitrogen（ADN）and effective phosphorus（EP）content,promoted nutrient uptake by the rice root system,increased rice growth and yield as well as photosynthetic rate,alleviated oxidative damage caused by PS-MPs and Cd stress,and resulted in down-regulation of MDA content and activities of antioxidant enzymes（SOD/CAT/POD）.The treatment of 1500 mg-L-1 Si-NPs alone at the tasseling stage was the most effective,resulting in a significant increase in plant height,aboveground fresh weight and net photosynthetic rate by 14.3%,8.6%and 70.3%,respectively,compared with the control（P<0.05）.In addition,Si-NPs promoted the accumulation of mineral elements in various parts of rice,facilitated the physiological and biochemical activities of rice,and especially increased the mineral element content of seeds,which is important for the nutritional value of seeds.（4）Foliar application of Si-NPs increased the soil p H and the content and percentage of Cd in residue state,reduced the transport toxicity of soil Cd,and inhibited the uptake of soil Cd by rice roots;foliar application of Si-NPs enriched Cd in oxalic acid state in large quantities in the leaves,and inhibited the redistribution of Cd from the leaves to the seeds.The single application of 1500 mg-L-1 Si-NPs treatment at the tasseling stage was the best treatment,which significantly reduced the BCF_plant/soil,TF_seed/leaf,and TF_seed/hullby 41.5%,71.7%,and 36.4%,respectively,and increased the TF _leaf/stemby 113.4%compared with that of the control treatment（P<0.05）.In summary,this study systematically investigated the effects of different concentrations of PS-MPs and Cd single and composite pollution on soil physicochemical properties,rice growth and yield,and physiological and biochemical indexes,and clarified the characteristics related to the accumulation,transport and storage of Cd in the soil-rice system under the single and composite pollution of different concentrations of PS-MPs and Cd;it also systematically explored the effects of foliar spraying of Si The effects of foliar spraying of Si-NPs on soil physicochemical properties,rice growth and yield,and physiological and biochemical indexes under the combined pollution of PS-MPs and Cd were systematically investigated,and the effects of foliar spraying of Si-NPs on the accumulation,transport and storage of Cd in the soil-rice system were elucidated,as well as the potential mechanisms.更多还原