Abstract
Because of enhanced anthropogenic nitrogen input, eutrophication, hypoxia, and acidification threaten the health of aquatic ecosystems. To better understand the current state of research and emerging trends in this area, a bibliometric approach was applied to quantitatively evaluate global nitrogen research at the watershed scale. Using 9,748 articles selected from among 10,163 returned by a search in the Science Citation Index Expanded (SCI-Expanded) database from 1900 to 2011, spatial and temporal characteristics of the articles, authors, institutions, countries, and keywords are presented, and focal research areas are derived. Compared with the annual increase in all articles in the SCI-Expanded (4.5 %), the studies on nitrogen in watersheds increased more quickly (11.2 %), indicating an increasing interest in this area. The relationship between authors and their output was evaluated by a two-step function, in which 6,074 authors (26.8 %) publishing on this topic were key scientists who contributed 56.4 % of the total articles. Based on the number of authors, first authors, international collaborators, and citations, four types of authors were analyzed using cluster methods. The influence of the authors, institutions and countries was also analyzed in terms of publication and citation, and a co-occurrence analysis was used to assess cooperation among countries and research hotpots. The keywords were compared among countries to assist our understanding of interests of research and modes. From the analysis of the primary subjects and the co-occurrence of keywords, studies involving nitrogen’s environmental effects, the nitrogen process and models are increasing, which indicates that they are likely to become a primary research focus in the near future.
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References
Ashrafi, F., Mohammadhassanzadeh, H., Shokraneh, F., Valinejadi, A., Johari, K., Saemi, N., et al. (2012). Iranians’ contribution to world literature on neuroscience. Health Information and Libraries Journal, 29, 323–332.
Bornmann, L., & Marx, W. (2012). HistCite analysis of papers constituting the h index research front. Journal of Informetrics, 6, 285–288.
Canfield, D. E., Glazer, A. N., & Falkowski, P. G. (2010). The evolution and future of earth’s nitrogen cycle. Science, 330, 192–196.
Fu, H. Z., Wang, M. H., & Ho, Y. S. (2013). Mapping of drinking water research: A bibliometric analysis of research output during 1992-2011. Science of the Total Environment, 443, 757–765.
Galloway, J. N., Dentener, F. J., Capone, D. G., Boyer, E. W., Howarth, R. W., Seitzinger, S. P., et al. (2004). Nitrogen cycles: Past, present, and future. Biogeochemistry, 70, 153–226.
Ho, Y. S. (2013). The top-cited research works in the Science Citation Index Expanded. Scientometrics, 94, 1297–1312.
Ho, Y. S., Satoh, H., & Lin, S. Y. (2010). Japanese lung cancer research trends and performance in Science Citation Index. Internal Medicine, 49, 2219–2228.
Hu, J., Ma, Y. W., Zhang, L., Gan, F. X., & Ho, Y. S. (2010). A historical review and bibliometric analysis of research on lead in drinking water field from 1991 to 2007. Science of the Total Environment, 408, 1738–1744.
Kimura, S. D., Yan, X. Y., Hatano, R., Hayakawa, A., Kohyama, K., Ti, C. P., et al. (2012). Influence of agricultural activity on nitrogen budget in Chinese and Japanese Watersheds. Pedosphere, 22, 137–151.
Li, L. L., Ding, G. H., Feng, N., Wang, M. H., & Ho, Y. S. (2009). Global stem cell research trend: Bibliometric analysis as a tool for mapping of trends from 1991 to 2006. Scientometrics, 80, 39–58.
Li, T., Ho, Y. S., & Li, C. Y. (2008). Bibliometric analysis on global Parkinson’s disease research trends during 1991–2006. Neuroscience Letters, 441, 248–252.
Li, J. F., Wang, M. H., & Ho, Y. S. (2011). Trends in research on global climate change: A Science Citation Index Expanded-based analysis. Global and Planetary Change, 77, 13–20.
Persson, O. D., Danell, R., & Wiborg Schneider, J. (2009). How to use Bibexcel for various types of bibliometric analysis. In F. Åström, R. Danell, B. Larsen & J. Schneider (Eds.), In celebrating scholarly communication studies: A Festschrift for Olle Persson at his 60th Birthday (pp. 9–24). International Society for Scientometrics and Informetrics.
Rajagopal, T., Archunan, G., Surulinathi, M., & Ponmanickam, P. (2013). Research output in pheromone biology: a case study of India. Scientometrics, 94, 711–719.
Rockstrom, J., Steffen, W., Noone, K., Persson, A., Chapin, F. S., Lambin, E. F., et al. (2009). A safe operating space for humanity. Nature, 461, 472–475.
Suk, F. M., Lien, G. S., Yu, T. C., & Ho, Y. S. (2011). Global trends in Helicobacter pylori research from 1991 to 2008 analyzed with the Science Citation Index Expanded. European Journal of Gastroenterology and Hepatology, 23, 295–301.
Sun, J. S., Wang, M. H., & Ho, Y. S. (2012). A historical review and bibliometric analysis of research on estuary pollution. Marine Pollution Bulletin, 64, 13–21.
Swaney, D. P., Hong, B. G., Ti, C. P., Howarth, R. W., & Humborg, C. (2012). Net anthropogenic nitrogen inputs to watersheds and riverine N export to coastal waters: a brief overview. Current Opinion in Environmental Sustainability, 4, 203–211.
Townsend, A. R., Howarth, R. W., Bazzaz, F. A., Booth, M. S., Cleveland, C. C., Collinge, S. K., et al. (2003). Human health effects of a changing global nitrogen cycle. Frontiers in Ecology and the Environment, 1, 240–246.
Vitousek, P. M. (1994). Beyond global warming: Ecology and global change. Ecology, 75, 1861–1876.
Vitousek, P. M., Aber, J. D., Howarth, R. W., Likens, G. E., Matson, P. A., Schindler, D. W., et al. (1997). Human alteration of the global nitrogen cycle: Sources and consequences. Ecological Applications, 7, 737–750.
Vitousek, P. M., & Howarth, R. W. (1991). Nitrogen limitation on land and in the sea: How can it occur. Biogeochemistry, 13, 87–115.
Wen, H. C., Ho, Y. S., Jian, W. S., Li, H. C., & Hsu, Y. H. E. (2007). Scientific production of electronic health record research, 1991–2005. Computer Methods and Programs in Biomedicine, 86, 191–196.
Yu, J. J., Wang, M. H., Xu, M., & Ho, Y. S. (2012). A bibliometric analysis of research papers published on photosynthesis: 1992–2009. Photosynthetica, 50, 5–14.
Zhang, L. A., Wang, M. H., Hu, J., & Ho, Y. S. (2010a). A review of published wetland research, 1991–2008: Ecological engineering and ecosystem restoration. Ecological Engineering, 36, 973–980.
Zhang, G. F., Xie, S. D., & Ho, Y. S. (2010b). A bibliometric analysis of world volatile organic compounds research trends. Scientometrics, 83, 477–492.
Zhang, T., & Yang, X. J. (2013). Predicting nitrogen loading with land-cover composition: How can watershed size affect model performance? Environmental Management, 51, 96–107.
Zhi, W., & Ji, G. D. (2012). Constructed wetlands, 1991–2011: A review of research development, current trends, and future directions. Science of the Total Environment, 441, 19–27.
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Gao, W., Guo, HC. Nitrogen research at watershed scale: a bibliometric analysis during 1959–2011. Scientometrics 99, 737–753 (2014). https://doi.org/10.1007/s11192-014-1240-8
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DOI: https://doi.org/10.1007/s11192-014-1240-8