@article {120,
	title = {Sulfate reduction in lake sediments inhabited by the isoetid macrophytes Littorelia uniflora and isoetes lacustris},
	journal = {Aquatic Botany},
	volume = {60},
	year = {1998},
	note = {Cited By (since 1996):22Export Date: 11 November 2013Source: Scopus},
	month = {1998///},
	pages = {307 - 324},
	abstract = {Sulfur cycling was examined in sediments inhabited with the isoetids Littorella uniflora and Isoetes lacustris in the oligotrophic soft-water Lake Kalgaard, Denmark. Based on short-term tracer incubations sulfate reduction was measured along a transect from the shore (0.6 m) to profundal sediments (4.6 m). The sulfate reduction rates were low (0.008-0.8 mmol m-2 d-1) in the sandy shallow sediments with low organic content (\&lt; 1.3 mmol C g-1 sed DW) and high redox potentials (\&gt; 100 mV), whereas sulfate reduction was higher at the deeper sites (2.7-4.6 mmol m-2 d-1) with high organic content (max. 11.5 mmol C g-1 sed DW) and lower redox potentials (\&lt; 100 mV). High concentrations of dissolved organic carbon (DOC) were found in the low particulate organic sediments (up to 18.4 mM), and most of the DOC pool consisted of acetate (40-77\%). Reoxidation of sulfides due to root oxygen release was probably important at all sites and a positive efflux of sulfate across the sediment-water interface was measured, attaining rates (up to 4.8 mmol m-2 d-1) similar to the sulfate reduction rates. Reoxidation of sulfides was also manifested by high fraction (\&gt; 80\%) of reduced sulfides being accumulated as elemental sulfur or pyrite (chromium reducible sulfur, CRS). The largest pools of CRS were found in high organic sediment with vertical distributions resembling those of the sulfate reduction rates. The overall effect of isoetid growth on sulfur cycling in the rhizosphere is a suppression of sulfate reduction in low organic sediments and the governing of sulfide reoxictation in sediments with higher organic content.},
	keywords = {Dissolved organic carbon, Freshwater, Submerged macrophytes, Sulfate reduction, Sulfur pools},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0032051759\&partnerID=40\&md5=cedb9f2713f49909e7234473be0de561},
	author = {Holmer, M. and Jensen, H.S. and Christensen, K.K. and Wigand, C. and Andersen, F.O.}
}
@article {83,
	title = {Water velocity and irradiance effects on internal transport and metabolism of methane in submerged Isoetes alpinus and Potamogeton crispus},
	journal = {Aquatic Botany},
	volume = {79},
	year = {2004},
	note = {Cited By (since 1996):3Export Date: 11 November 2013Source: Scopus},
	month = {2004///},
	pages = {189 - 202},
	abstract = {Submerged aquatic macrophytes are important methane (CH4) transport pathways, but little is known about how water velocity and illumination affect plant CH4 transport. We studied CH4 transport in vitro in fully-submerged plants of two aquatic macrophytes, Isoetes alpinus and Potamogeton crispus, comparing transport between two water velocities (0.5 and 90 mm s-1) and light versus dark treatments at the shoots. In I. alpinus, CH4 taken up by the roots accumulated in the lacunar system of the leaves at concentrations \&gt;40 μmol l-1 at both flow rates, but there was no release from the shoots to the water at flow = 0.5 mm s-1, whereas at 90 mm s-1 release from the shoots to the water was always \&gt;0.15 μmol (CH4 g-1 dry wt. h-1). Uptake of CH4 by the roots was 1.5 times greater at the higher than the lower water velocity. In P. crispus, a gradient in lacunar [CH4] developed from the base to the apex of the shoot and was steeper at the higher than the lower water velocity. CH4 release rates from the shoots were \&lt;0.1 μmol (CH4 g-1 dry wt. h-1) at both water velocities in this species, due to CH 4 consumption by epiphytic methanotrophic bacteria. Irradiance and its associated root aeration had no effect on CH4 transport in I. alpinus, but decreased root to shoot CH4 transport and release more than 10-fold in P. crispus, apparently by alleviating effects of hypoxia on the root-associated methanotrophic bacteria. Our data support the view that plant-associated methanotrophs are important CH4 sinks in freshwater habitats, and demonstrate the importance of flow velocity in the CH4 dynamics of submerged macrophytes. {\textcopyright} 2004 Elsevier B.V. All rights reserved.},
	keywords = {CH4, Diffusion, Lacunar system, O2, Submerged macrophytes},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-2642545092\&partnerID=40\&md5=9d9974a9e87e34dbe2225f98137ef822},
	author = {Sorrell, B.K. and Downes, M.T.}
}
