Epilithon isotope composition as an environmental archive in rivers receiving wastewater

Abstract

Epilithon is a complex community of autotrophic and heterotrophic organisms that includes inert, organic and inorganic material and is attached to the surface of submersed rocks. Water samples collected in the Grand River (southwestern Ontario) in April 2011 showed that ammonium concentrations decreased downstream, whereas nitrate varied, largely dependent on weather conditions (concentrations of both chemical species were higher during winter). Epilithon δ15N-TN downstream from the Kitchener wastewater treatment plant oscillated between 0.4 to 23.2‰, and δ13C-TC around -27‰. The wastewater treatment plant effluent consisted of δ15N-NO3- between 12 and 16‰, with a decreasing trend as it traveled downstream; δ15N-NH4+ became enriched downstream (as high as 31‰). Average values for δ13C-DIC were -10.1‰ and δ13C-DOC -26.8‰. It is proposed that the nitrogen and carbon isotope composition of epilithon could be used as a short- or medium-term environmental archive, as it reflects in-stream processes, such as ammonia oxidation, in a river impacted by treated wastewater. The interpretation provided here was limited due to the ample range of events and potential sources, specifically when the nitrogen isotopic composition of nitrate and ammonium was similar. Epilithon is easily collected, processed and analysed and proved to be valuable tool to describe changes in river and stream geochemistry.

Epilithon δ15N signatures indicate the origins of nitrogen loading and its seasonal dynamics in a volcanic Lake

“…Indeed, consistent with our expectations and with previous research into macroalgal and epilithic δ 15 N signatures in several non-lacustrine aquatic ecosystems (Bentivoglio et al, 2016;Cejudo et al, 2014;Dailer et al, 2010;Jona-Lasinio et al, 2015;Pastor et al, 2014), we found that the magnitude and type of input reaching the lake littoral zone varied strongly in space and time. Accordingly, the δ 15 N values associated with these inputs were found to vary across sites and seasonally.…”

“…There is a strong need therefore for an accurate, practical and fast environmental monitoring tool. In marine, coastal, transitional water and lotic ecosystems, macroalgal and epilithic δ 15 N signatures have proved to be successful in determining the types and space-time variability of nitrogen loads (Bentivoglio et al, 2016;Cejudo et al, 2014;Cole et al, 2004;Dailer et al, 2010;Gartner et al, 2002;Jona-Lasinio et al, 2015;Orlandi et al, 2014, Pastor et al, 2013Peipoch et al, 2012;Schiller et al, 2009;Titlyanov et al, 2011;Vizzini et al, 2005), while in lacustrine ecosystems there is a lack of knowledge concerning epilithic δ 15 N signatures.…”

“…Given their ability to assimilate and store N inputs in their tissues, macroalgae (in marine ecosystems) and epilithon (in river ecosystems) can provide information on anthropogenic N loadings based on changes in their isotopic signatures (Cejudo et al, 2014;Cole et al, 2004;Costanzo et al, 2005;Jones et al, 2004;Pastor et al, 2014;Schiller et al, 2009;Yokoyama and Ishihi, 2006), even on short time scales (Orlandi et al, 2014), reflecting space-time variability in N availability (Jona-Lasinio et al, 2015;Vizzini et al, 2005). Several studies have been performed on macroalgal δ 15 N signatures in marine coastal ecosystems (Cole et al, 2004;Dailer et al, 2010;Gartner et al, 2002;Titlyanov et al, 2011) and coastal brackish lakes (Jona-Lasinio et al, 2015) and lagoons (Vizzini et al, 2005).…”

“…Several studies have been performed on macroalgal δ 15 N signatures in marine coastal ecosystems (Cole et al, 2004;Dailer et al, 2010;Gartner et al, 2002;Titlyanov et al, 2011) and coastal brackish lakes (Jona-Lasinio et al, 2015) and lagoons (Vizzini et al, 2005). Recent studies have applied stable isotope analysis to epilithic δ 15 N signatures to evaluate the effect of anthropic land use on rivers (Bentivoglio et al, 2016;Cejudo et al, 2014;Pastor et al, 2013Pastor et al, , 2014Peipoch et al, 2012;Schiller et al, 2009). However, in spite of its widespread presence, epilithon is poorly understood as an ecological indicator of nitrogen pollution.…”

Decolorization of mono azo dye methyl orange with Epilithon biofilm: effects of physico-chemical parameters

“…Epilithon biofilms are composed principally of algae, bacteria, protozoa and other smaller invertebrates (Cejudo, 2014) that are embedded in extracellular polymeric substance (EPS) including proteins, organic acids and minerals (Azim, 2005). The abundance and structure of these biofilms are dependent on the physico-chemical and environmental conditions (Sabater, 1998;Hillebrand, 2000).…”