生态语言学作为一门兴起的交叉学科，其中产生的两个分支——豪根模式和韩礼德模式近些年来正受到学界广泛的关注。生态话语分析作为韩礼德模式的主要实现形式，近年来在语篇分析中的地位也越来越得到彰显。本文采用了何伟、高然和刘佳欢（2021）提出的对生态语言学扩展后的评价系统作为理论框架，开展中美日三家主流媒体关于日本核污水报道这一事件的生态话语分析，比较其在生态取向分布特点、评价资源对分布特点贡献上的异同。研究发现中国媒体在这一生态事件中传递的生态有益型话语显著多于日方和美方，而日方和美方之间则无显著差异。同时，中日的生态有益型话语主要来自态度资源的贡献，美方则来自介入资源。通过揭露三家媒体背后的生态取向，该研究为今后的媒体更好地利用评价资源传递积极的生态声音提供了启发。

Ecolinguistics, as an emerging interdisciplinary subject, has gained widespread attention in recent years, particularly for its two major branches, the Haugen model and the Hallidayan model. Ecological discourse analysis, as the main manifestation of the Hallidayan model, has increasingly become prominent in discourse analysis. This thesis aims to conduct an analysis of ecological discourses in the reporting of Japan's nuclear-contaminated water issue by three media outlets in China, Japan, and America using the ecological theoretical framework from the perspective of Appraisal adapted by He, Gao and Liu (2021). By comparing the distribution of ecological orientation and the contribution of appraisal resources to the distribution among the three media, we found that Chinese media conveyed significantly more eco-beneficial discourse in this ecological event compared to the Japanese and American sides, while no significant differences were observed between the Japanese and American media. Besides, we also figured out that eco-beneficial discourse between China and Japan was primarily derived from the contribution of attitude resources, whereas that of American stemmed from engagement resources. By uncovering the ecological orientations behind these media outlets, the thesis could offer inspiration for future media and help them better utilize appraisal resources in conveying positive ecological messages.