Mapping the scientific research on non-point source pollution: a bibliometric analysis.

A bibliometric analysis was conducted to examine the progress and future research trends of non-point source (NPS) pollution during the years 1991-2015 based on the Science Citation Index Expanded (SCI-Expanded) of Web of Science (WoS). The publications referencing NPS pollution were analyzed including the following aspects: document type, publication language, publication output and characteristics, subject category, source journal, distribution of country and institution, author keywords, etc. The results indicate that the study of NPS pollution demonstrated a sharply increasing trend since 1991. Article and English were the most commonly used document type and language. Environmental sciences and ecology, water resources, and engineering were the top three subject categories. Water science and technology ranked first in distribution of journal, followed by Science of the total environment and Environmental Monitoring and Assessment. The USA took a leading position in both quantity and quality, playing an important role in the research field of NPS pollution, followed by the UK and China. The most productive institution was the Chinese Academy of Sciences (Chinese Acad Sci), followed by Beijing Normal University and US Department of Agriculture's Agricultural Research Service (USDA ARS). The analysis of author keywords indicates that the major hotspots of NPS pollution from 1991 to 2015 contained "water," "model," "agriculture," "nitrogen," "phosphorus," etc. The results provide a comprehensive understanding of NPS pollution research and help readers to establish the future research directions.