The biotic contribution to the benthic stream sediment phosphorus buffer
- PDF / 855,610 Bytes
- 17 Pages / 547.087 x 737.008 pts Page_size
- 7 Downloads / 182 Views
(0123456789().,-volV) (0123456789().,-volV)
The biotic contribution to the benthic stream sediment phosphorus buffer Z. P. Simpson
. R. W. McDowell . L. M. Condron
Received: 7 May 2020 / Accepted: 8 October 2020 / Published online: 17 October 2020 Ó Springer Nature Switzerland AG 2020
Abstract Benthic stream sediments interact strongly with phosphorus (P) and can buffer dissolved reactive P (DRP) concentrations. The sediment P buffer can be measured with the sediment equilibrium phosphate concentration at net zero sorption (EPC0), which often correlates well with DRP. Yet, it is unclear how much of this P affinity in sediments is attributable to biotic (microbial P demand) or abiotic (sorption) processes. To clarify the role of biotic processes on EPC0, we used two experiments with benthic sediment from 12 streams. First, sediments sterilized by c-irradiation increased in EPC0 compared to fresh sediments by a median of 83%. This increase in EPC0 was likely a result of cell lysis, where microbial biomass P (2.4 to 22.6 mg P kg-1) was re-adsorbed to sediment surfaces. This data also shows that the sediment microbial biomass is a significant, yet under-reported biotic
stock of P in streams compared to their photic zone counterpart (i.e., periphyton). In a second experiment, fresh sediment EPC0 was measured after alleviating potential limitation of carbon (C) and nitrogen (N) for microbial growth. Sediment EPC0 did not change with C addition and decreased slightly (0.5 lg P L-1 or * 5% decrease) with N addition, suggesting these sediments strongly buffered DRP towards the EPC0 in spite of biotic demand. Together, these experiments suggest that sediment EPC0 was primarily abiotic in nature but that sediments may subsidize biotic P requirements through desorption. Further work is needed on whether this relation holds for streams with different substrate, geology, and nutrient inputs. Keywords Phosphorus Sediment Streams Microbial biomass Buffer EPC0
Responsible Editor: Amy M. Marcarelli.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10533-020-00709-z) contains supplementary material, which is available to authorized users. Z. P. Simpson (&) R. W. McDowell L. M. Condron Department of Soil and Physical Sciences, Lincoln University, Lincoln, New Zealand e-mail: [email protected] R. W. McDowell AgResearch, Lincoln Science Centre, Lincoln, New Zealand
Introduction Benthic sediments provide much of the phosphorus (P) attenuation observed in streams (Haggard and Sharpley 2007; Hamilton 2012). Sediments contain inorganic particles of varying sizes and geochemical characteristics derived from the parent material, which determine the sites available for P sorption (House 2003). Sediments also contain allochthonous and autochthonous stocks of organic matter (OM; Tank
123
64
et al. 2010; Kaplan and Cory 2016), providing fuel for the metabolism of sediment microbial biofilms (Battin et al. 2016). These characteristics make the sediment matrix a hotspot of bioge
Data Loading...
