社会化媒体不仅深刻影响和改变着人们的生活方式，也改变着环境舆情的形成与扩散的方式。随着公众的环境维权意识增强及传播意愿不断提升，环境舆情传播呈多主体、多维度、多层次态势。本研究采用定量和定性相结合的方法，在分析社会化媒体舆情生态系统的基础上，揭示了环境舆情扩散主体的行为特征，研究了社会化媒体中环境舆情的扩散动力与扩散路径。在此基础上，剖析了影响社会化媒体舆情扩散的因素，建构了环境舆情信息阅读量预测模型及环境舆情风险测量指标体系，并提出了环境舆情风险防范策略。 环境风险的社会放大效应、群体极化导致的情绪偏激、移情效应情感投射加强代入感是环境舆情风险的主要来源。社会化媒体中环境舆情扩散主体分布广泛且诉求多元。研究发现，环境舆情扩散中网民以中青年为主，女性比例高于男性。来自城市和环境污染地的网民环境风险感知度更高。有家庭子女的用户，对环境的敏感程度更强烈。环保意识水平、环境风险认知水平、用户需求是影响网民的扩散意愿主要因素。用户需求正向影响网民对环境污染信息的转发意愿。信息类型和呈现形式影响用户的转发行为，信息来源影响网民的信任程度和转发意愿，社交关系的强度影响网民的环境信息的交流行为。 社会化媒体中环境舆情的扩散是环境舆情生态系统各要素在内部动力和外部动力共同驱动下的结果。环境舆情主体会受到环境舆情事件、个体心理、社会化媒体舆情的传播环境以及现实社会中环境利益关系等多因素的复合影响。环境事件本身的危害性、敏感度和公共性特征赋予环境舆情主体以强大的动力，驱使网民不断参与环境舆情的扩散。基于安全需求、尊重需求、认知需求、社交需求、利他行为的共同成为网民环境舆情扩散的内生动力。 转型期社会的环境矛盾积累与现实沟通渠道的不畅，叠加作用于社会化媒体中的环境舆情事件，使得社会化媒体成为环境舆情情感与诉求表达的主要渠道。环境舆情主体间现实关系的敏感复杂则营造了环境舆情扩散的现实空间。意见领袖的转发扩散推动着环境舆情信息在更大范围内的传播，网民的环境诉求与环境管理部门舆情回应的错位，影响着环境舆情主体的环境风险感知，进一步推动了网民对环境舆情信息扩散的行为，是社会化媒体中环境舆情扩散的外部动力。 关系网已成为社会化媒体中环境舆情扩散的重要渠道。事件的见证者是关系网中环境舆情信息的主要来源，网民的积极转发形成舆情扩散的接力，环境管理部门、主流媒体介入汇聚成扩散合力，环境舆情信息的流转呈现出多层级扩散特点。在环境舆情的扩散路径结构中，每一个扩散主体都可能作为一个节点参与到多个扩散链条的传播活动中。不同属性的节点对环境舆情的扩散起到不同的作用。转发量大、参与人数多的舆情信息呈现出单核爆发式的扩散结构。单点引爆形成环境舆情扩散的基本单元，多节点联动触发推动环境舆情的多层级扩散，节点间层级链接拓展了环境舆情扩散路径的的深度。 社会化媒体中环境舆情扩散受多种因素的影响。环境舆情信息的阅读量与转发量、评论量、点赞量呈显著正相关，转发量、点赞量、评论量为建构环境舆情信息阅读量预测模型提供了基础。环境事件性质影响舆情信息的扩散力和关注度，公众的传播行为助推环境舆情的形成与扩散，意见领袖的传播影响环境风险舆情的能量和走向，不同的风险传播模式、话语形态和民众渴求的信息解读模式成为影响环境舆情扩散的重要因素。环境风险的社会放大、官方舆情处置不当、不法分子借机炒作等因素易引发环境舆情风险。 依据社会化媒体中环境舆情风险的测量指标，建构了基于Yaahp的环境舆情风险评估结构模型，为感知社会化媒体中环境舆情风险提供参考。媒体与环境管理部分及时回应公众对环境问题的关切，建立公开透明的工作机制，不断提升与公众的环境风险沟通能力有助于化解舆情风险。了解环境舆情扩散规律是舆情风险防范的基础。保障公众环境风险知情权，控制对环境风险的社会放大效应；优化环境舆情的传播生态，提高环境风险传播主体的舆情素养，社会化媒体中环境舆情风险防范需要多方共同的努力。 关键词：社会化媒体；环境舆情扩散；环境舆情风险防范

 Social media not only profoundly influences and changes people's way of life, but also changes the way of the formation and diffusion of environmental public opinion. With the enhancement of the public's awareness of environmental rights protection and the increasing willingness to spread, the spread of environmental opinion is becoming multi-subject, multi-dimensional and multi-level. By using both quantitative and qualitative research method, this study reveals the behavior characteristics of the subject of environmental public opinion diffusion, and studies the motive and path of diffusion of the environmental public opinion in social media on the basis of analyzing the social media public opinion ecosystem. On this basis, this paper analyzes the factors that affect the spread of public opinion in social media, constructs the prediction model of environmental public opinion information reading quantity and the index system of environmental public opinion risk measurement, and puts forward the risk prevention strategy of environmental public opinion. The social amplification effect of environmental risk, the emotional extreme caused by group polarization, the empathy effect and the emotional projection strengthening the sense of subrogation are the main sources of environmental public opinion risk. In social media, the main body of environmental public opinion diffusion is widely distributed and the appeal is multi-element. The study found that in the spread of environmental public opinion, netizens are mainly young and middle-aged, and the proportion of women is higher than that of men. Netizens from urban and environmentally mental polluted areas have a higher perception of environmental risk. Users with children are more sensitive to the environment. Environmental awareness level, environmental risk cognition level and user demand are the main factors that affect the diffusion willingness of netizens. Positive user demand affects the netizen's willingness to transmit information about environmental pollution. The type of information and the form of rendering affect the user's forwarding behavior. The source of information affects the level of trust of netizens and the willingness to forward, and the intensity of social relations affects the communication behavior of netizens' environmental information. The diffusion of environmental public opinion in social media is the result of the combination of internal power and external power of various elements of environmental public opinion ecosystem. The subject of environmental public opinion will be influenced by many factors, such as environmental public opinion events, individual psychology, the communication environment of social media public opinion, and the relationship of environmental interests in the real society. The harmfulness, sensitivity and public characteristics of environmental events themselves give the subject of environmental opinion a strong motive, which drives netizens to continuously participate in the spread of environmental public opinion. The security needs, demand for respect, cognitive needs, social needs, altruistic behavior become the endogenous driving force for the netizens to spread environmental public opinion. The accumulation of environmental contradictions in the transitional society and the poor communication channels in reality, superimposed on the environmental public opinion events in the social media, make the social media become the main channel to express the emotion and appeal of environmental public opinion. The sensitivity and complexity of the realistic relationship among the subjects of environmental public opinion creates the realistic space for the spread of environmental public opinion. The forwarding and diffusion of opinion leaders promotes the spread of the information of environmental public opinion in a wider scope. The dislocation of the environmental demand of netizens and the Environmental Management Department’s response to the public opinion, affects the environmental risk perception of the subject of environmental public opinion, and further promotes the Internet users’ behavior of spreading the information of environmental public opinion, and is the external motive for the spread of environmental public opinion. Relationship network has become an important channel for the spread of environmental public opinion in social media. The witness of the event is the main source of environmental public opinion information in the network, The active participation of netizens forms the relay of the spread of public opinion, the intervention of Environmental management department and mainstream media converges into the diffusion force, and the circulation of environmental public opinion information presents the characteristics of multi-level diffusion. In the diffusion path structure of environmental public opinion, each diffusion subject may participate as a node in the propagation activities of multiple diffusion chains. The nodes of different attributes play different roles in the diffusion of environmental public opinion. The public opinion information with a large number of forwarders and participants presents a single-nucleus explosive diffusion structure. Single-point detonation forms the basic unit of environmental public opinion diffusion. Multi-node linkage triggers and promotes the multi-level diffusion of environmental public opinion. Inter-node hierarchical links expand the depth of environmental public opinion diffusion path. The spread of environmental public opinion in social media is influenced by many factors. The reading amount of environmental public opinion information is positively correlated with the amount of forwarding and the amount of comment and the amount of praise. The amount of forwarding, the amount of praise and the amount of comments provide the basis for the construction of the prediction model of environmental public opinion information reading volume. The nature of environmental events affects the diffusive force and attention of public opinion information, and the communication behavior of the people boosts the formation and diffusion of environmental opinion, and the communication of opinion leaders affects the energy and trend of environmental risk public opinion. The different modes of risk communication, discourse forms and the information interpretation modes that the population craves have become the important factors that affect the spread of environmental opinion. Social amplification of environmental risks, improper disposal of official public opinion, illegal elements to hype and other factors easily trigger environmental public opinion risk. According to the measurement index of environmental public opinion risk in social media, the structure model of environmental public opinion risk assessment based on Yaahp was constructed, which provided reference for perceiving the risk of environmental public opinion in social media. The media and environmental management components’s responding to public concerns about environmental issues in a timely manner, establishing open and transparent working mechanisms, and continuously improving their ability to communicate with the public on environmental risks, which can help to defuse the risks of public opinion. Understanding the law of environmental public opinion diffusion is the basis of public opinion risk prevention. In order to protect the public’s right to know about the environmental risk, control the social amplification effect of environmental risks, optimize the environment of environmental opinion dissemination, improve the public opinion literacy of the environmental risk communication subject, prevention of environmental public opinion risk in social media needs the joint efforts of multiple parties. Keywords: Social media, Environmental public opinion diffusion, Risk prevention of environmental public opinion