Abstract
The stable nitrogen (N) isotope ratio (δ15N) has been used to examine the anthropogenic N input (i.e., septic water, wastewater, and manure) to aquatic ecosystems, because anthropogenic N generally has a δ15N signature distinct from that found in nature. Aquatic organisms and the derived organic matter such as sediments are reported to become increasingly enriched in 15N as the human population density increases in watersheds. However, little is known about the relationship in steppe ecosystems, where the livestock population is greater than that of humans. Here, we conducted a preliminary study in the Selenga river mainstream watershed in Mongolia, which covers an area of approximately 300,000 km2. A multiple regression analysis revealed that the δ15N of the riverine sediment was significantly affected by the human population density and more significantly by livestock population density. The population density, including both humans and livestock, significantly influenced δ15N of the macrophytic Potamogeton spp. The results showed that δ15N of riverine organic matter can be an indicator of the human and livestock population density, which is likely associated with the status of N cycles in livestock-dominated watersheds.
References
Anderson C, Cabana G (2006) Does δ15N in river food webs reflect the intensity and origin of N loads from the watershed? Sci Total Environ 367:968–978
Anonymous (1990) National atlas of the Mongolian People’s Republic (in Russian and English). Academy of Sciences of Mongolia, Ulan Baataar
Benson ER, O’Neil JM, Dennison WC (2008) Using the aquatic macrophyte Vallisneria americana (wild celery) as a nutrient bioindicator. Hydrobiologia 596:187–196
Boone RB, Lackett JM, Galvin KA, Ojima DS, Tucker CJ (2007) Links and broken chains: evidence of human-caused changes in land cover in remotely sensed images. Environ Sci Policy 10:135–149
Cabana G, Rasmussen JB (1996) Comparison of aquatic food chains using nitrogen isotopes. Proc Natl Acad Sci USA 93:10844–10847
Elliott EM, Brush GS (2006) Sedimented organic nitrogen isotopes in freshwater wetlands record long-term changes in watershed nitrogen source and land use. Environ Sci Technol 40:2910–2916
Grubov VL (2001) Key to the vascular plants of Mongolia, vol I. Science, Enfield
Heaton THE (1986) Isotopic studies of nitrogen pollution in the hydrosphere and atmosphere: a review. Chem Geol 59:87–102
Hodell DA, Schelske CL (1998) Production, sedimentation, and isotopic composition of organic matter in Lake Ontario. Limnol Oceanogr 43:200–214
Humphrey C, Sneath D (1999) The end of nomadism? Society, state and the environment in Inner Asia. Duke University Press, Durham
Hyodo F, Tsugeki N, Azuma J, Urabe J, Nakanishi M, Wada E (2008) Changes in stable isotopes, lignin-derived phenols, and fossil pigments in sediments of Lake Biwa, Japan: implications for anthropogenic effects over the last 100 years. Sci Total Environ 403:139–147
Kendall C (1998) Tracing nitrogen sources and cycles in catchments. In: Kendall C, McDonnell JJ (eds) Isotope tracers in catchment hydrology. Elsevier, Amsterdam, pp 519–576
Kohzu A, Miyajima T, Tayasu I, Yoshimizu C, Hyodo F, Matsui K, Nakano T, Wada E, Fujita N, Nagata T (2008) Use of stable nitrogen isotope signatures of riparian macrophytes as an indicator of anthropogenic N inputs to river ecosystems. Environ Sci Technol 42:7837–7841
Kohzu A, Tayasu I, Yoshimizu C, Maruyama A, Kohmatsu Y, Hyodo F, Onoda Y, Igeta A, Matsui K, Nakano T, Wada E, Nagata T, Takemon Y (2009) Nitrogen-stable isotopic signatures of basal food items, primary consumers and omnivores in rivers with different levels of human impact. Ecol Res 24:127–136
Kozhov M (1963) Lake Baikal and its life. Dr. Junk, The Hague
Ma X, Yasunari T, Ohata T, Natsagdorj L, Davaa G, Oyunbaatar D (2003) Hydrological regime analysis of the Selenge River basin, Mongolia. Hydrol Process 17:2929–2945
McClelland JW, Valiela I, Michener RH (1997) Nitrogen-stable isotope signatures in estuarine food webs: a record of increasing urbanization in coastal watersheds. Limnol Oceanogr 42:930–937
Mearns R (2004) Sustaining livelihoods on Mongolia’s pastoral commons: insights from a participatory poverty assessment. Dev Change 35:107–139
Neupert RF (1999) Population, nomadic pastoralism and the environment in the Mongolian plateau. Popul Environ 20:413–441
Ogawa NO, Koitabashi T, Oda H, Nakamura T, Ohkouchi N, Wada E (2001) Fluctuations of nitrogen isotope ratio of gobiid fish (Isaza) specimens and sediments in Lake Biwa, Japan, during the 20th century. Limnol Oceanogr 46:1228–1236
Retzer V, Reudenbach C (2005) Modelling the carrying capacity and coexistence of pika and livestock in the mountain steppe of the South Gobi, Mongolia. Ecol Model 189:89–104
Retzer V, Nadrowski K, Miehe G (2006) Variation of precipitation and its effect on phytomass production and consumption by livestock and large wild herbivores along an altitudinal gradient during a drought, South Gobi, Mongolia. J Arid Environ 66:135–150
Saizen I, Maekawa A, Yamamura N (2010) Spatial analysis of time-series changes in livestock distribution by detection of local spatial associations in Mongolia. Appl Geogr 30:639–649
Schmidt-Nielsen K (1984) Scaling: Why is animal size so important? Cambridge University Press, Cambridge
Tachiiri K, Shinoda M, Klinkenberg B, Morinaga Y (2008) Assessing Mongolian snow disaster risk using livestock and satellite data. J Arid Environ 72:2251–2263
Umezawa Y, Miyajima T, Yamamuro M, Kayanne H, Koike I (2002) Fine-scale mapping of land-derived nitrogen in coral reefs by δ15N in macroalgae. Limnol Oceanogr 47:1405–1416
Wada E, Hattori A (1991) Nitrogen in the sea. CRC, Boca Raton
Acknowledgments
We appreciate the helpful comments on the earlier draft of this manuscript afforded by the two anonymous reviewers. This study was supported by the Research Institute for Humanity and Nature (P3-1 and D-04), by a grant-in-aid from JSPS to N.F., and partly by a Special Coordination Fund for Promoting Sciences and Technology from the Japanese Ministry of Education, Science, and Culture.
Author information
Authors and Affiliations
Corresponding author
Appendix
Appendix
See Table 2.
Rights and permissions
About this article
Cite this article
Hyodo, F., Nishikawa, J., Kohzu, A. et al. Variation in nitrogen isotopic composition in the Selenga river watershed, Mongolia. Limnology 13, 155–161 (2012). https://doi.org/10.1007/s10201-011-0351-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10201-011-0351-7