Biogenic silica in wetlands and their relationship with soil and groundwater biogeochemistry in the Southeastern of Buenos Aires Province, Argentina

Abstract

Although phytoliths constitute part of the wetland suspended load, there are few studies focused on the quantification of them in the biogenic silica (BSi) pool. So, the aim of this paper is both to determine BSi content (diatoms and phytoliths) and its relationship with dissolved silica in surface waters, and the influence of soil and groundwater Si biogeochemistry in Los Padres wetland (Buenos Aires Province, Argentina). In the basin of the Los Padres wetland, dissolved silica (DSi) concentration is near 840 ± 232 lmol/L and 211.83 ± 275.92 lmol/L in groundwaters and surface waters, respectively. BSi represents an 5.6-22.1% of the total suspension material, and 8-34% of the total mineralogical components of the wetland bottom sediments. DSi and BSi vary seasonally, with highest BSi content (diatoms specifically) during the spring-summer in correlation to the lowest DSi concentration. DSi (660-917.5 lmol/L) and phytolith (3.35-5.84%) concentrations in the inflow stream are higher than in the wetland and its outflow stream (19.1-113 lmol/L; 0.45-3.2%, respectively), probably due to the high phytolith content in soils, the high silica concentration in the soil solution, and the groundwater inflow. Diatom content (5-16.8%) in the wetland and its outflow stream is higher than in the inflow stream (0.45-1.97%), controlling DSi in this system. The understanding of the groundwater-surface water interaction in an area is a significant element for determining the different components and the role that they play on the local biogeochemical cycle of Si.

Silica biogeochemical cycle in temperate ecosystems of the Pampean Plain, Argentina

“…The importance of silicon (second most abundant element in the earth's crust) is due to occurs in most of the minerales forming rocks and parent materials of soils (Sommer et al, 2006); and for its quality as an important nutrient that controls the functioning of terrestrial, marine, coastal and inland water ecosystems (Ragueneau et al, 2002;Conley, 2002;Farmer et al, 2005;Borrelli et al, 2012). Although there are several studies focused on the marine silica cycle, the interest in the terrestrial silica cycle has recently begun to increase, since it is involved in the global carbon cycle and much of the reactive Si reaching the oceans has undergone prior biological cycling on the continents through the biomineralization process (Conley, 2002).…”

Silicon accumulation controls carbon cycle in wetlands through modifying nutrients stoichiometry and lignin synthesis of Phragmites australis

“…Wetlands are characterized by active biogeochemical cycling of Si, exhibiting strong control on catchment scale Si fluxes (Struyf and Conley, 2009;Borrelli et al, 2012), and a strong impact on source and sink for Si from plants has been highlighted (e.g., Struyf et al, 2005Struyf et al, , 2007Struyf et al, , 2010Opdekamp et al, 2012). Owing to the annual defoliation and decomposition of P. australis in autumn and winter, the stored BSi can also be released through biomass decomposition, while uptake occurs during net primary productivity.…”

Reassessing Groundwater Potentials and Subsurface water Hydrochemistry in a Tropical Anambra Basin, Southeastern Nigeria

“…Silica analysis in Nando and Udi by Egbunike [53] and Aniebone [128] , showed that it ranged from <0.001 to 30 mg/l (Figure 18). Silica is the most plentiful element found in rocks and it is constantly present in natural waters [129][130][131] . The element is a foremost constituent of the structure of diatoms (Bacillariophyta), one of the major groups of the algae, and when algal growth takes place in a water silica levels drop as the diatom population increases.…”