Cluster Analysis and Mapping Thematic Trends in the Environmental Studies: A Scientometric Study

This study examines the conceptual structure of environmental research indexed in the (ISC) database, identifying subfields and key dimensions of the environmental concept. Through quantitative analysis of studies from 1998 to 2023, the scientific structure of environmental research was explored, revealing main research clusters, conceptual dimensions, and key topics within each cluster. Using scientometric techniques and co-word analysis, 1,985 documents from the ISC database were analyzed to identify trends in environmental research during the specified period. Cluster analysis and strategic diagrams were employed to map the conceptual structure of the study, identify subfields, and explore relationships between them. The conceptual structure of this field comprises seven clusters: (1) Environmental law and ethics, (2) Environmental innovation ecosystem, (3) Iran’s economy and environment, (4) Urban pollution and sustainability, (5) Environmental behavior and awareness, (6) Environmental safety and health, and (7) Sustainable development education. Additionally, content analysis of articles published over 26 years identified emerging topics in environmental studies. The clusters reflect the key dimensions and topics within this field. The findings guide researchers and policymakers to allocate resources toward strategic, impactful, and underdeveloped areas. This study also aids in strategic planning, identifying research gaps, and clarifying future research directions.
Extended Abstract
1-Introduction        
Today, the world faces challenges stemming from environmental pollution. In recent decades, environmental studies have emerged as an interdisciplinary field to address escalating ecological challenges such as climate change, biodiversity loss, pollution, and natural resource crises. By integrating diverse disciplines—including ecology, economics, law, sociology, and modern technologies—this field seeks to balance sustainable development with ecosystem preservation.
Despite the vast volume of environmental research, the thematic dispersion and interdisciplinary nature of studies have made identifying core concepts, mapping subfield connections, and tracing the evolution of ideas a critical challenge. Scientometric studies using quantitative methods and visualization tools enable the analysis of co-citation networks, scientific collaborations, and keyword co-occurrence. This study adopts a scientometric approach and employs specialized software to identify dominant thematic clusters and core concepts in environmental research. By mapping the conceptual structure of this field, the research not only aids scholars in identifying future directions but also assists policymakers and funding institutions in aligning resources with priority areas. This effort represents a step toward harmonizing scientific endeavors with pressing environmental needs.
2-Materials and Methods
This applied research employs scientometric techniques, including co-word analysis and network analysis, to explore the intellectual structure of environmental studies. Data were processed using VOSviewer, UCINET, and BibExcel software. The dataset was extracted from the Islamic World Science Citation Center (ISC) database using the keyword “environment” and spans 26 years (1998–2023), comprising 1,985 documents. These documents included 8,236 author-provided keywords. After extracting plain text files from the ISC database, BibExcel was used to identify key terms (nouns or noun phrases) through natural language processing techniques. A frequency threshold of 6 was applied to filter out insignificant or erroneous terms, ensuring only meaningful keywords were kept. A symmetric matrix was generated in BibExcel and converted into a correlation matrix before being imported into VOSviewer for further analysis. The dataset underwent standardization to merge singular/plural forms, acronyms, and synonyms. For example, terms like “environmental education” and “eco-education” were unified under the most frequent variant. After standardization, 4,535 unique keywords remained. A 156x156 matrix was created, with diagonal cell values set to zero to exclude self-references. Cluster analysis was performed using the k-means method in VOSviewer to visualize thematic networks.
3- Results and Discussion
The keywords “environment” (frequency: 445), “sustainable development” (126), and “environmental education” (78) ranked as the top three most frequently terms. Co-word analysis revealed seven thematic clusters: (1) Environmental law and ethics, (2) Environmental innovation ecosystem, (3) Iran’s economy and environment, (4) Urban pollution and sustainability, (5) Environmental behavior and awareness, (6) Environmental safety and health, and (7) Sustainable development education. A strategic diagram analysis (based on centrality and density scores) categorized these clusters into four quadrants: The strategic diagram highlights Iran’s environmental research priorities and gaps. Quadrant I clusters (Economy and Environment, Behavior and Awareness) dominate because of their alignment with national challenges like balancing economic growth with ecological preservation and fostering public engagement in sustainability. These mature themes reflect Iran’s focus on mitigating industrial pollution and promoting environmental literacy. Quadrant II’s sustainable development education, though methodologically robust, remains siloed from core economic-environmental debates. Strengthening its linkages with policy frameworks and interdisciplinary collaborations could amplify its impact. Quadrant III’s emerging clusters (Innovation, Urban Pollution, Safety) suffer from conceptual fragmentation. For instance, Environmental Innovation lacks coherence, with sparse connections to practical applications like green technology. Similarly, Urban Pollution studies focus narrowly on cities like Tehran, overlooking systemic issues like heavy metal contamination. These areas demand targeted funding and interdisciplinary research to transition from marginal to mainstream status. Quadrant IV’s Environmental Law and Ethics holds potential but struggles with internal consistency. Integrating foundational concepts (e.g., citizen rights, compensation mechanisms) with macro-policy frameworks (e.g., circular economy models) could merge its role in shaping Iran’s environmental governance.
4- Conclusion
This study underscores the need to strengthen connections between core and peripheral clusters, enhance conceptual coherence, and adopt integrated policymaking in Iran’s environmental research. While economic-environmental interactions and behavioral studies dominate, emerging themes like innovation, urban sustainability, and environmental health remain underdeveloped.
To address these gaps, researchers and policymakers should prioritize: 1. Funding Emerging Themes: Redirect resources to understudied areas like environmental innovation and urban pollution to bridge research-practice gaps. 2. Interdisciplinary Collaboration: Foster partnerships among economists, technologists, educators, and legal experts to tackle complex environmental challenges holistically. 3. Policy Integration: Develop context-specific regulations (e.g., indigenous environmental laws) to support clusters like Environmental Law and Ethics. 4. Global Alignment: Align local research with global trends (e.g., ESG frameworks) while addressing Iran’s unique socio-ecological contexts. By addressing these priorities, Iran’s environmental research can evolve from foundational studies to actionable, globally relevant solutions, ensuring alignment with both national needs and international sustainability goals.