Temporal Variability of Nitrogen Stable Isotopes in Primary Uptake Compartments in Four Streams Differing in Human Impacts

详细信息    查看全文

• 作者：Ada Pastor ; Joan Llu铆s Riera ; Marc Peipoch ; L铆dia Ca帽as ; Miquel Ribot ; Esperan莽a Gacia ; Eug猫nia Mart铆 ; Francesc Sabater
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：June 17, 2014
• 年：2014
• 卷：48
• 期：12
• 页码：6612-6619
• 全文大小：356K
• 年卷期：v.48,no.12(June 17, 2014)
• ISSN：1520-5851

文摘

Understanding the variability of the natural abundance in nitrogen stable isotopes (expressed as 未¹⁵N) of primary uptake compartments (PUCs; e.g., epilithon or macrophytes) is important due to the multiple applications of stable isotopes in freshwater research and can give insights into environmental and anthropogenic factors controlling N dynamics in streams. While previous research has shown how 未¹⁵N of PUCs varies with 未¹⁵N of dissolved inorganic N (DIN) among streams, less is known about how 未¹⁵N of PUCs varies over time. Here, we examined monthly variation of 未¹⁵N of PUCs and of DIN species (nitrate and ammonium) over a year, and compared it among streams with contrasting human impacts and PUC types. Our results showed no evidence of isotopic seasonal patterns. Temporal variability in 未¹⁵N-PUCs increased with human impact, being the highest in the urban stream, probably influenced by the high variability of 未¹⁵N-DIN. Among compartments, in-stream PUCs characterized by fast turnover rates, such as filamentous algae, showed the highest temporal variability in 未¹⁵N values (from 鈭?.6 to 23.2 鈥?. Our study elucidates some of the environmental and biological controls of temporal variability of 未¹⁵N in streams, which should be taken into account when using stable isotopes as an ecological tool.