Are benthic nutrient fluxes from intertidal mudflats driven by surface sediment characteristics?

Abstract

Are benthic nutrient fluxes from intertidal mudflats driven by surface sediment characteristics?

Linking sediment biodegradability with its origin in shallow coastal environments

“…This suggests that anthropogenic inputs, such as sewage discharges or agricultural runoff, rich in fecal matter would be positively impacting the PO4 fluxes from the sediment. The RDA also showed a positive relationship between the PO4 flux and the Org-P and Fe-P contents, as previously observed for the same sediments (Louis et al, 2021). This may highlight the concomitance of Org-P mineralization 580…”

“…The measurement method of NH4 + and PO4 fluxes was totally described in the companion paper Louis et al (2021).…”

“…Canonical redundancy analysis (RDA) and variance partitioning were used to explain the spatial variability of the NH4 + and PO4 fluxes 110 and the mineralization rates into independent parameters related to 1) the variation of SOM composition and origin and 2) the variation of the chemical composition and physical properties of sediment. All study sites were macrotidal mudflats, located in Brittany, north-western France, and have been already fully 115 described in a companion paper (Louis et al, 2021). Overall, 200 sediment samples were collected on 45 sites and classified into 12 mudflats (Fig.…”

“…and organic P (Org-P) contents, which represented the pool of potentially bioavailable P. The analytical method was totally described in the companion paper Louis et al (2021). Briefly, the Fe-P content was determined using a Dithionite-Bicarbonate solution (Ruttenberg et al, 1992), and the Org-P content was quantified by calculating the difference between the total P and inorganic P (sums of Fe-bound P, Ca-bound P and detrital P) contents as described in Andrieux-Loyer et al (2008).…”

How the origin of sedimentary organic matter impacts the benthic nutrient fluxes in shallow coastal mudflats

“…The composition of SOM was studied by a combination of isotopic (δ 13 C and δ 15 N values) and lipid (aliphatic hydrocarbons (n-alkanes and hopanes), sterols and stanols, fatty acids, fatty alcohols, and aromatic hydrocarbons including polycyclic aromatic hydrocarbons-PAH) analyses classically used to investigate the sources of SOM [Freese et al, 2008, Volkman et al, 2000. The ability of sediments to release NH + 4 and PO 3− 4 fluxes through diffusion were determined using incubations with intact sediment cores under the same ambient experimental conditions (dark, controlled temperature, artificial overlying water) [Louis et al, 2021]. Finally such a dataset allows the use of canonical redundancy analysis (RDA) and variance partitioning in order to explain the spatial variability of the NH + 4 and PO 3− 4 fluxes as independent parameters related to (i) the variation of the SOM origin (elemental and isotopic ratios, lipid markers) and (ii) the variation of the elemental composition (N, P, C) and physical properties (grain size, porosity) of the sediment [from Louis et al, 2021].…”