Abstract:Saline wetlands have received limited attention from researchers and this neglect has often resulted in their degradation and limited conservation, and insufficient information to design conservation and management plans. Gallocanta Lake is a nature reserve of international importance for winter birds. The importance of the soil here, which supports niches and protected habitats for certain species of birds, has been recognized more recently. The soil of Gallocanta Lake undergoes strong oscillations of saturat… Show more
“…Furthermore, site C, which is closer to the centre of the lake, had a higher conductivity compared to A and B (45 ± 4 mS/cm). Chlorine and bicarbonate concentrations were not measured in this study but concentrations reported previously, considering cross-shore variations, reached up to 1890 and 14 mM, respectively 23 , 30 . Figure 1 Study site.…”
“…S6 ). Dissolved sulphide and iron sulphides such as framboidal pyrite, which can form in sediments containing ferrous iron and sulphide 26 , have been previously detected in Gallocanta Lake 25 , 26 , 30 . Also, in site B purple bacteria were observed in the water overlying the sediment cores immediately after collection, suggesting further sulphide oxidation on the water–sediment interface (Fig.…”
Section: Sulphur Cycling Processes In a Sulphate Rich Systemmentioning
The sulphur cycle has a key role on the fate of nutrients through its several interconnected reactions. Although sulphur cycling in aquatic ecosystems has been thoroughly studied since the early 70’s, its characterisation in saline endorheic lakes still deserves further exploration. Gallocanta Lake (NE Spain) is an ephemeral saline inland lake whose main sulphate source is found on the lake bed minerals and leads to dissolved sulphate concentrations higher than those of seawater. An integrative study including geochemical and isotopic characterization of surface water, porewater and sediment has been performed to address how sulphur cycling is constrained by the geological background. In freshwater and marine environments, sulphate concentration decreases with depth are commonly associated with bacterial sulphate reduction (BSR). However, in Gallocanta Lake sulphate concentrations in porewater increase from 60 mM at the water–sediment interface to 230 mM at 25 cm depth. This extreme increase could be caused by dissolution of the sulphate rich mineral epsomite (MgSO4·7H2O). Sulphur isotopic data was used to validate this hypothesis and demonstrate the occurrence of BSR near the water–sediment interface. This dynamic prevents methane production and release from the anoxic sediment, which is advantageous in the current context of global warming. These results underline that geological context should be considered in future biogeochemical studies of inland lakes with higher potential availability of electron acceptors in the lake bed compared to the water column.
“…Furthermore, site C, which is closer to the centre of the lake, had a higher conductivity compared to A and B (45 ± 4 mS/cm). Chlorine and bicarbonate concentrations were not measured in this study but concentrations reported previously, considering cross-shore variations, reached up to 1890 and 14 mM, respectively 23 , 30 . Figure 1 Study site.…”
“…S6 ). Dissolved sulphide and iron sulphides such as framboidal pyrite, which can form in sediments containing ferrous iron and sulphide 26 , have been previously detected in Gallocanta Lake 25 , 26 , 30 . Also, in site B purple bacteria were observed in the water overlying the sediment cores immediately after collection, suggesting further sulphide oxidation on the water–sediment interface (Fig.…”
Section: Sulphur Cycling Processes In a Sulphate Rich Systemmentioning
The sulphur cycle has a key role on the fate of nutrients through its several interconnected reactions. Although sulphur cycling in aquatic ecosystems has been thoroughly studied since the early 70’s, its characterisation in saline endorheic lakes still deserves further exploration. Gallocanta Lake (NE Spain) is an ephemeral saline inland lake whose main sulphate source is found on the lake bed minerals and leads to dissolved sulphate concentrations higher than those of seawater. An integrative study including geochemical and isotopic characterization of surface water, porewater and sediment has been performed to address how sulphur cycling is constrained by the geological background. In freshwater and marine environments, sulphate concentration decreases with depth are commonly associated with bacterial sulphate reduction (BSR). However, in Gallocanta Lake sulphate concentrations in porewater increase from 60 mM at the water–sediment interface to 230 mM at 25 cm depth. This extreme increase could be caused by dissolution of the sulphate rich mineral epsomite (MgSO4·7H2O). Sulphur isotopic data was used to validate this hypothesis and demonstrate the occurrence of BSR near the water–sediment interface. This dynamic prevents methane production and release from the anoxic sediment, which is advantageous in the current context of global warming. These results underline that geological context should be considered in future biogeochemical studies of inland lakes with higher potential availability of electron acceptors in the lake bed compared to the water column.
“…events (Tian et al, 2017), the P released into the surface water of Gallocanta Lake may accumulate in the soil at the lake edge, especially under anaerobic conditions (Castañeda et al, 2017), as probably occurs at GA19 (7.4 mg kg -1 , Table 2).…”
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“…The Indicator of Reduction in Soils (IRIS) is one of three U.S.‐approved techniques (NRCS, 2015) used to demonstrate soils are reducing (Berkowitz & Sallee, 2011; Castañeda, Luna, & Rabenhorst, 2017; Hodges, King, Pett‐Ridge, & Thompson, 2018). Iron‐oxide IRIS rely on iron reduction (Jenkinson & Franzmeier, 2006; Castenson & Rabenhorst, 2006).…”
Indicator of Reduction In Soils (IRIS) technology is an important tool for identifying hydric soils, but it does not allow the user to monitor in real time. IRIS uses metal‐oxide coatings on a polyvinyl chloride surface that, under anaerobic conditions, are removed to varying degrees over a 4‐wk incubation period, during which time the user is not cognizant of the outcome. We document the viability of an alternative IRIS approach using clear‐IRIS tubes, made from cellulose acetate butyrate, that can be continuously monitored in situ with a Wi‐Fi–enabled video camera. This work shows that IRIS and clear‐IRIS tubes are statistically equivalent. Manganese‐oxide coated clear‐IRIS tubes correlated well with IRIS tubes (r = .79) and ferrous‐oxide had a high correlation (r = .97). A time‐series analysis showed that rain‐driven soil saturation induced IRIS metal‐oxide reduction and controlled the rate. Clear‐IRIS tubes enable remote sensing of metal‐oxide removal over time.
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