Inland saline ecosystems suffer multiple stresses (e.g., high radiation, salinity, water scarcity) that may compromise essential ecosystem functions such as organic matter decomposition. Here, we ...investigated the effects of drought on microbial colonization and decomposition of Sarcocornia fruticosa woody stems across different habitats in a saline watershed: on the dry floodplain, submerged in the stream channel and at the shoreline (first submerged, then emerged). Unexpectedly, weight loss was not enhanced in the submerged stems, while decomposition process differed between habitats. On the floodplain, it was dominated by fungi and high cellulolytic activity; in submerged conditions, a diverse community of bacteria and high ligninolytic activity dominated; and, on the shoreline, enzyme activities were like submerged conditions, but with a fungal community similar to the dry conditions. Results indicate distinct degradation paths being driven by different stress factors: strong water scarcity and photodegradation in dry conditions, and high salinity and reduced oxygen in wet conditions. This suggests that fungi are more resistant to drought, and bacteria to salinity. Overall, in saline watersheds, variations in multiple stress factors exert distinct environmental filters on bacteria and fungi and their role in the decomposition of plant material, affecting carbon cycling and microbial interactions.
Different stress factors, such as salinity, sunlight radiation and oxygen concentration, along with water availability, have varying impacts on the microbial decomposition of plant material. In the floodplain, this process is primarily driven by fungi and hydrolytic activities. In contrast, the saline stream channel sees a dominance of bacteria and ligninolytic activity. However, microbial activities are significantly compromised at the intermittent shoreline.
This study aimed to assess the effectiveness of biochar from sewage sludge -BSS- and from pruning trees -BPT- (addition dose of 6% d.w.) to immobilise metals in acidic (pH ∼ 4.7) and basic (pH ∼ 7.4) ...mine soils under variable flooding conditions, and to determine biochar influence on plant (Sarcocornia fruticosa -Sf-) growth and metal uptake. BSS had lower pH (∼8.2 vs. ∼ 9.8), CaCO3 (∼71 vs. ∼ 85 g kg−1), total organic carbon (∼354 vs. ∼ 656 g kg−1) and higher water soluble organic carbon (WSOC ∼ 0.15 vs ∼ 0.06 mg kg−1) than BPT. PVC columns (15 × 30 cm) were prepared with the following treatments (n = 4): 1) no Biochar-no Sf; 2) no Biochar-Sf; 3) BSS-no Sf; 4) BSS-Sf; 5) BPT-no Sf; 6) BPT-Sf. Changes in water table level (WL) were simulated for 303 days with tap water (upper 0–15 cm alternating flooding-drying conditions, lower 15–30 cm always underwater). The pH, redox potential (Eh), temperature and porewater WSOC, Zn, Cd and Pb concentrations were regularly measured, and plants were removed at the end and length, fresh weight and metal concentrations in tissues measured. In the basic soil, there were no consistent evidences that BSS and BPT were effective decreasing porewater metal concentrations and reducing metal uptake in plants. Sf contributed to mobilise Zn, and in less extent Cd, in the upper soil layer, regardless of the type of biochar, and this effect increased with aging. In the acidic soil, BSS and BPT were effective increasing the pH and decreasing porewater metals. BSS increased its efficiency with aging, which can be mainly attributable to the more reduced conditions that induced (lower Eh values) due to its higher WSOC content. Biochar was effective hindering metal mobilisation by Sf and reducing plant's metal uptake (e.g. reduction in roots: ∼7 fold for Zn, ∼19-fold for Cd and ∼ 2-fold for Pb). BSS was more effective promoting Sf growth (fresh weight) than BPT. Therefore, in relation with the use of biochar from sewage sludge and from pruning trees as soil amendments under flooding-non flooding conditions, we can conclude that it can be a useful option in acidic mine soils for decreasing water soluble metals and improving plant growth. However, in basic mine soils, we have no evidences to support the advantages of using these two types of biochar as amendments. Hence, the use of biochar in metal-polluted wetlands has environmental implications that must be planned for each specific case in order to optimize the positive aspects (wetland as sinks of pollutants) and reduce the drawbacks (wetland as source of pollutants).
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•Hydric mine soils were amended with biochar from sewage sludge and pruning trees.•Biochar did not modify the pH and porewater metals in hydric basic mine soils.•Biochar increased the pH and decreased porewater metals in hydric acidic mine soils.•Flooding regime, temperature and plants modulated biochar effectiveness.•Biochar reduced plant's metal uptake in acidic but not in basic hydric mine soils.
This study aims to characterize soil properties and to investigate how these parameters, including soil salinity, are related to zonation and distributional patterns of halophytic plants occurring at ...edges of the Djendli Sabkha (northeastern Algeria). Soil samples were collected from four stations at Sabkha edges with seven samples for each station. Physicochemical soil parameters were analysed in each vegetation belt of halophytes. Relationships between soil traits were tested to determine spatial variation and their effects on vegetation cover of the principal halophyte species. The influence of pedological factors on the distribution and establishment of halophytes was considered using a redundancy analysis (RDA) and generalized linear models. Positive correlations were found between organic matter, carbon and nitrogen which were negatively correlated with electrical conductivity (EC), pH, gypsum, Na+ and Cl− concentrations. Sharp limits were found between halophyte communities even though there is a gradual change in the physicochemical environment along the gradient centre-to-edge of the Sabkha. RDA showed that edaphic variables that best explained the data were EC, pH, organic matter (OM), carbon and nitrogen contents, Na+ and Cl− concentrations. Sarcocornia fruticosa grew under higher soil salinity (EC=7.2–13.8dS/m) compared to Suaeda fruticosa and Suaeda vermiculata that afford moderate soil salinity, than Atriplex halimus established in soils with low EC values (5.5–7.3dS/m) but with high values of OM, carbon and nitrogen contents and low values of Na+, Cl− and pH. Sarcocornia fruticosa grew in soils characterized with high pH, Na+, Cl− values but relatively low in OM, carbon and nitrogen contents.
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•Soil salinity, pH, gypsum, Na, Cl are negatively correlated with organic matter (OM), C and N•Sarcocornia fruticosa grew under high soil salinity, pH, Na, Cl, near moist lake edges•Gypsum contents influenced the variation of vegetation cover of halophyte plants•Suaeda fruticosa and Su. vermiculata grew in moderate saline soils, Atriplex halimus in low saline soils rich in OM, C, and N•Halophyte ranges ensued along soil gradients following species‐specific tolerance levels
Pollination is a key process in the life cycle of most plant species, but very little is known about airborne pollen dispersal in salt marsh anemophilous halophytes. We analyzed the temporal and ...spatial dynamics of airborne pollen dispersal, using portable volumetric pollen traps, for six anemophilous Chenopodiaceae halophytic species in tidal salt marshes. In addition, we studied the effects of air temperature and wind speed on airborne pollen dispersal. Our study shows high levels of temporal and spatial constraint on airborne pollen dispersal. We recorded the lowest airborne pollen concentrations at air temperatures lower than 22 °C and wind speeds higher than 6 m s−1. These environmental conditions set up a narrow temporal pollination window during morning hours. We also recorded severe spatial limitation for pollen dispersal in three of the six halophytes studied, which presented airborne pollen concentrations that were 9 to 53 times smaller only 5 m away from source populations than within those populations. These results show that even related species colonizing the same ecosystem may show contrasted airborne pollen spatial dispersal dynamics that depend on several environmental factors. This should be taken into account for estimates of vegetation composition based on pollen production in aerobiological and paleopalinological studies. The restricted airborne pollen dispersal recorded would promote geitonogamy and limit interpopulation genetic exchange to the dispersal of their hydrochorous fruits.
•Airborne pollen concentrations decreased c. 90% at temperatures lower than 22 °C.•Airborne pollen concentrations decreased c. 90% at wind speed higher than 6 m s−1.•Environmental conditions set up a narrow temporal pollination window.•Airborne pollen was mostly dispersed during a few morning hours.•Pollen concentration decreased markedly 5 m away in 3 of the 6 halophytes studied.
The work was conducted at La Pletera salt marsh (NE Spain) to investigate the potential for atmospheric carbon capture of perennial Sarcocornia fruticosa (L.) Scott and annual Salicornia patula Duval ...Jouve and subsequent carbon integration and storage into S. fruticosa and S. patula soils respectively, at 0–5 and 5–20 cm depth. S. fruticosa amounts of aboveground (aC), belowground (bC) and litter (lC) carbon were 2300%, 350% and 3000% higher than S. patula according to the respective plant, root and litter biomass. This dramatic difference was reflected in soil organic carbon (SOC) values, much higher in S. fruticosa soil at 0–5 cm depth with 17.07 ± 5.83 g kg−1 than S. patula soil with 5.89 ± 1.68 g kg−1, namely 189% increase. Similarly, SOC increased by 109% in S. fruticosa soil at 5–20 cm depth. This perennial species can accumulate great amount of decaying debris at surface, which would gradually decompose by microbial activity to increase the soil organic carbon stock. Furthermore, the organic carbon incorporated is of better quality because contains higher fractions of glomalin, a stable organic compound known for its important role in soil aggregate stability. In fact, glomalin related soil protein (GRSP) was 292% and 182% higher in S. fruticosa than S. patula at the two depths respectively. By contrast, the low amount and nature of decaying debris produced in S. patula are easily mineralized and lesser organic carbon is consequently incorporated into soil. Lower SOC and GRSP affected the soil aggregate stability (WSA) in the 0.25–2 mm and 2–5.6 mm aggregate fractions, considerably more detachable in S. patula soil. Moreover, this soil exhibited the highest mineralization coefficient (Qm) at both depths, 125% and 175% higher than S. fruticosa soil respectively, and a major sensitivity to carbon loss. The PCA further highlighted the ability of S. fruticosa habitat to act as a carbon sink. Results may be valuable for salt marsh vegetation management addressed to mitigate climate change and increase ecosystem services.
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•Salt marsh soils relevant for organic carbon assimilation and storage•Glomalin production in salt marsh soils as important recalcitrant form of carbon•Major ability of conservative carbon dynamics in soil under Sarcocornia fruticosa•Annual characteristics of Salicornia patula cause carbon assimilation constraint.
Coexistence impact of pollutants of different nature on halophytes tolerance to metal excess has not been thoroughly examined, and plant functional responses described so far do not follow a clear ...pattern. Using the Cu-tolerant halophyte Sarcocornia fruticosa as a model species, we conducted a greenhouse experiment to evaluate the impact of two concentration of copper (0 and 12 mM CuSO4) in combination with three nitrate levels (2, 14 and 50 mM KNO3) on plant growth, photosynthetic apparatus performance and ROS-scavenging enzymes system. The results revealed that S. fruticosa was able to grow adequately even when exposed to high concentrations of copper and nitrate. This response was linked to the plant capacity to uptake and retain a large amount of copper in its roots (up to 1500 mg kg−1 Cu), preventing its transport to aerial parts. This control of translocation was further magnified with nitrate concentration increment. Likewise, although Cu excess impaired S. fruticosa carbon assimilation capacity, the plant was able to downregulate its light-harvesting complexes function, as indicated its lowers ETR values, especially at 12 mM Cu + 50 mM NO3. This downregulation would contribute to avoid excess energy absorption and transformation. In addition, this strategy of avoiding excess energy was accompanied by the upregulation of all ROS-scavenging enzymes, a response that was further enhanced by the increase in nitrate concentration. Therefore, we conclude that the coexistence of nitrate would favor S. fruticosa tolerance to copper excess, and this effect is mediated by the combined activation of several tolerance mechanisms.
•Role of nitrate on the Cu tolerance of the halophytic S. fruticosa remain unknown.•Nitrate reduces Cu excess impact on photosynthetic apparatus yield under Cu stress.•Nitrate had a positive effect on photosystem light harvest energy efficiency.•Nitrate contribute to maintain plant water use efficiency.•Enzyme oxidative machinery was modulated by nitrate presence.
Seed germination and seedling establishment are very sensitive plant stages to metal pollution. Many halophyte species colonizing salt marshes are able to germinate and establish in highly ...contaminated habitats and low marsh halophyte species seem to show higher tolerance to metals than high marsh species. We analyzed the effects of copper, zinc and nickel in concentrations up to 2000 μM on seed germination and seedling growth in two closely related species of Sarcocornia, S. perennis, a low marsh species, and S. fruticosa, a high marsh species. Germination of both halophytes was not affected by any metal concentration, and their seedling growth, mainly radicle length, was reduced by increasing metal concentrations. Seedlings of S. perennis showed higher tolerance to the three metals than those of S. fruticosa. Our results are useful for designing ecotoxicological bioassays and planning phytoremediation projects in salt marshes.
•Germination of S. perennis and S. fruticosa was not affected by any metal concentration.•Seedling growth, mainly radicle length, was reduced by increasing metal concentrations.•Seedlings of S. perennis showed higher tolerance to metals than those of S. fruticosa.
Treatment of tannery wastewater is problematic due to high and variable concentrations of complex pollutants often combined with high salinity levels. Two series of horizontal subsurface flow ...constructed wetlands (CWs) planted with
Arundo donax and
Sarcocornia fruticosa were set up after a conventional biological treatment system operating at a tannery site. The aim of the CWs was polishing organics and nitrogen from the high salinity effluent (2.2–6.6 g Cl
− L
−1). Both plant species established and grew well in the CW.
Arundo, however, had more vigorous growth and a higher capacity to take up nutrients. The CWs were efficient in removing COD and BOD
5 with removal efficiencies varying between 51 and 80% for COD (inlet: 68–425 mg L
−1) and between 53 and 90% for BOD
5 (inlet: 16–220 mg L
−1). Mass removal rates were up to 615 kg COD ha
−1 d
−1 and 363 BOD
5 kg ha
−1 d
−1. Removal efficiencies were 40–93% for total P, 31–89% for NH
4
+ and 41–90% for Total Kjeldahl Nitrogen. CW systems planted with salt tolerant plant species are a promising solution for polishing saline secondary effluent from the tannery industry to levels fulfilling the discharge standards.
► High salinity tannery wastewater can successfully be treated in constructed wetlands. ►
Arundo and
Sarcocornia tolerate high salinity tannery wastewater. ► Removal efficiencies of up to 80% for COD (inlet: 68–425 mg L
−1) were achieved. ► The effluent coming from the constructed wetlands fulfilled the discharge standards. ► For operational flexibility CW should be established with beds in series.
Ria Formosa lagoon is a coastal system in the south of Portugal, characterized by sediments contaminated from urban and industrial pollution emissions. In this study, sediments from two contrasted ...metal contamination level sites, colonized by Sarcocornia fruticosa were used in an on-site experimentation. The heavy metal removal efficiencies of S. fruticosa with and without bioaugmentation using autochthonous metal resistant isolated yeast (Saccharomyces cerevisiae) were compared.
After 15 days of incubation, the total amount of metal concentration (Cd, Pb, Ni, Cr, and Cu) in sediments and plant matter were compared. We found a striking difference between heavily contaminated site and less contaminated site. Metal reductions in heavily contaminated site were generated more by S. fruticosa which was inoculated with S. cerevisiae. In the less contaminated sediments, the higher percentage reductions were achieved with S. fruticosa alone. Our results indicate that despite the phytoremediation potential of S. fruticosa, the addition of S. cerevisiae, increases the plant phytoremediation capacity.
Pools of Zn, Cu, Cd and Co in leaf, stem and root tissues of
Sarcocornia fruticosa,
Sarcocornia perennis,
Halimione portulacoides and
Spartina maritima were analyzed on a bimonthly basis, in a Tagus ...estuary salt marsh. All the major concentrations were found in the root tissues, being the concentrations in the aboveground organs neglectable for sediment budget proposes, as seen by the low root-aboveground translocation. Metal annual accumulation, root turnovers and cycling coefficients were also assessed.
S. maritima showed the higher root turnovers and cycling coefficients for most of the analyzed metals, making this a phytostabilizer specie. By contrast the low root turnover, cycling coefficient and low root necromass generation makes
S. perennis the most suitable specie for phytoremediation processes. Although the high amounts of metal return to the sediments, due to root senescence, salt marshes can still be considered sinks of heavy metals, cycling heavy metals mostly between sediment and root.
The efficiency of the phytoremediative processes and metal budgets are greatly influenced by the turnover periods and necromass generation.
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