Transpiration of Scots pine in Flanders growing on soil with irregular substratum

An investigation was carried out to compare the water balance of Scots pine in Flanders growing on soils with contrasted water availability. Based on sap flow measurements transpiration of Scots pine was determined for two small plots on cover sands resting on a clayey substratum of varying depths (shallow and deep). Soil water content (SWC) was relatively low (0.12–0.21 m³ m⁻³) in the upper topsoil (0–0.75 m) in both plots. However, it was always higher in the shallow plot (by 3–27%) than in the deep plot. The difference between SWC in both plots was more pronounced in the deeper soil layers (0.75–1.5 m). Sap flow was measured in seven sample pine trees on each plot from May to October 2000 using the heat field deformation (HFD) method. Transpiration of the individual trees in the deep plot was 22% lower than in trees in the shallow plot. The difference decreased to 15% after scaling up to the stand level due to a higher density of trees growing in the deep plot. It was hypothesized that higher water uptake in the shallow plot was possibly caused by structural differences between the root systems of trees growing in plots with variable soil texture. The sapwood in shallow-plot trees was 1 cm less deep than in trees growing in the deep plot (as measured by biometric and sap flow pattern methods). Sap flow radial patterns suggested a higher involvement of sinker roots for water uptake in the deep clayey substratum plot. This was in agreement with higher activity of the inner xylem in trees on the deep plot under higher evaporative demands. However, the fraction of the inner xylem to the whole-tree water supply was nearly three-fold lower than the outer xylem, which appeared to provide water presumably from the superficial roots. The fraction of these roots, estimated according to sap flow radial patterns, was around 10% higher in trees on the shallow plot. This caused 30% higher sap flow in the stem outer xylem there. Transpiration of the pine stands was limited under high evaporative demands in both plots by the low availability of soil water. The limitation was greater in the deep plot and persisted throughout the whole growing season.     

Sap flux – a real time assessment of health status in Norway spruce

Top dieback of Norway spruce (Picea abies), triggered by drought in 2004–2006, has been observed in Southeast Norway and trees died within four years after appearance of the first symptoms. The aim of our study was to use sap flux measurements as a diagnostic method for assessment of tree vitality. We used the heat field deformation method to monitor the sap flux density (SFD) in four pairs of healthy and declining trees in situ. To provide retrospective information on hydraulic performance of the trees we took samples for wood anatomical analysis. After felling the trees we used the modified differential translucence method (MDT) as a proxy for the SFD measurements. Healthy trees had three times higher SFD values as declining trees. In some healthy trees we detected decreasing SFD with time. The MDT method agreed with the SFD measurements. In conclusion, we detected sap flux dysfunction in declining trees and showed that the SFD reduction may occur during a short period, prior to occurrence of any visual symptoms. We suggest incorporating the SFD measurements into the repertoire of diagnostic tools in forest pathology.     

Influence of Fucoidans on Hemostatic System

Three structurally different fucoidans from the brown seaweeds Saccharina latissima (SL), Fucus vesiculosus (FV), and Cladosiphon okamuranus (CO), two chemically modified fucoidans with a higher degree of sulfation (SL-S, CO-S), and a synthetic totally sulfated octasaccharide (OS), related to fucoidans, were assessed on anticoagulant and antithrombotic activities in different in vitro experiments. The effects were shown to depend on the structural features of the compounds tested. Native fucoidan SL with a degree of sulfation (DS) of 1.3 was found to be the most active sample, fucoidan FV (DS 0.9) demonstrated moderate activity, while the polysaccharide CO (DS 0.4) was inactive in all performed experiments, even at high concentrations. Additional introduction of sulfate groups into fucoidan SL slightly decreased the anticoagulant effect of SL-S, while sulfation of CO, giving rise to the preparation CO-S, increased the activity dramatically. The high level of anticoagulant activity of polysaccharides SL, SL-S, and CO-S was explained by their ability to form ternary complexes with ATIII-Xa and ATIII-IIa, as well as to bind directly to thrombin. Synthetic per-O-sulfated octasaccharide OS showed moderate anticoagulant effect, determined mainly by the interaction of OS with the factor Xa in the presence of ATIII. Comparable tendencies were observed in the antithrombotic properties of the compounds tested.     

Biological activity of carbonic nano-structures—comparison via enzymatic bioassay

Purpose

The aim of the work is to compare the biological activity of carbonic nano-structures of natural and artificial origination, namely, humic substances (HS) and fullerenols.

Materials and methods

The representative of the fullerenol group, С₆₀О_y(OH)_x where у?+?x?=?20–22, was chosen. Enzyme-based luminescent bioassay was applied to evaluate toxicity and antioxidant properties of HS and fullerenol (F); chemiluminescent luminol method was used to study a content of reactive oxygen species (ROS) in the solutions. Toxicity of the bioactive compounds was evaluated using effective concentrations ЕС₅₀; detoxification coefficients D_OxT were applied to study and compare antioxidant activity of the compounds. Antioxidant activity and ranges of active concentrations of the bioactive compounds were determined in model solutions of organic and inorganic oxidizers—1,4-benzoquinone and potassium ferricianide.

Results and discussion

Values of ЕС₅₀ revealed higher toxicity of HS than F (0.005 and 0.108 g L^?1, respectively); detoxifying concentrations of F were found to be lower. Antioxidant ability of HS was demonstrated to be time-dependent; the 50-min preliminary incubation in oxidizer solutions was suggested as optimal for the detoxification procedure. On the contrary, F’ antioxidant effect demonstrated independency on time. Antioxidant effect of HS did not depend on amphiphilic characteristics of the media (values of D_OxT were 1.3 in the solutions of organic and inorganic oxidizers), while this of F was found to depend: it was maximal (D_OxT?=?2.0) in solutions of organic oxidizer, 1,4-benzoquinone.

Conclusions

Both HS and F demonstrated toxicity and low-concentration antioxidant ability; however, quantitative characteristics of their effects were different. The differences were explained with HS polyfunctionality, higher ability to decrease ROS content, non-rigidity, and diffusion restrictions in their solutions. Antioxidant effect of the bioactive compounds was presumably attributed to catalytic redox activity of their π-fragments. The paper demonstrates a high potential of luminescent enzymatic bioassay to study biological activity of nano-structures of natural and artificial origination.

     

The amount of recycled crust in sources of mantle-derived melts

Plate tectonic processes introduce basaltic crust (as eclogite) into the peridotitic mantle. The proportions of these two sources in mantle melts are poorly understood. Silica-rich melts formed from eclogite react with peridotite, converting it to olivine-free pyroxenite. Partial melts of this hybrid pyroxenite are higher in nickel and silicon but poorer in manganese, calcium, and magnesium than melts of peridotite. Olivine phenocrysts' compositions record these differences and were used to quantify the contributions of pyroxenite-derived melts in mid-ocean ridge basalts (10 to 30%), ocean island and continental basalts (many >60%), and komatiites (20 to 30%). These results imply involvement of 2 to 20% (up to 28%) of recycled crust in mantle melting.     

Tracing Organic Footprints from Industrial Effluent Discharge in Recalcitrant Riverine Chromophoric Dissolved Organic Matter

Excitation?Cemission matrix fluorescence spectroscopy, combined with parallel factor analysis and measurements of UV absorption and dissolved organic carbon (DOC) concentrations, was used to trace the footprints of industrial effluents discharged into the lower Kishon River (Israel). The lower Kishon River typifies streams that are affected by seawater tidal intrusion and represents an extreme case of severe long-term pollution caused mainly by a variety of industrial effluents. The industrial effluents may contribute about 90%, in terms of biochemical oxygen demand, of the total organic carbon discharged into the lower Kishon River. Water samples were collected along the river, including the points of effluent discharge from industrial plants, between November 2005 and September 2006. Two types of fluorescent components characterized the fluorescence of the lower Kishon River water: component I corresponded to humic-like matter and component II spectrally resembled material known to be associated with biological productivity, but different from typical tryptophan-like fluorophore. These fluorescent components and other substances that absorbed light at 254 nm contributed to the DOC pool that resisted riverine microbial degradation under laboratory conditions, and that constitutes up to 70% of the overall riverine DOC. The variations in DOC concentration, absorbance at 254 nm, and concentration of humic-like matter (characterized by component I) correlated with the distance from the sea and the water electrical conductivity, and were linked to seawater tidal intrusion. The increased concentration of component II, as well as its enlarged fraction in the overall riverine DOC pool, was found to be associated with the location of major inputs of the industrial effluents. These findings support the use of this fluorescent component as an indicator of industrial pollution in such severely contaminated riverine systems.     

Stored water use and transpiration in Scots pine: a modeling analysis with ANAFORE

We estimated daily use of stored water by Scots pine (Pinus sylvestris L.) trees growing in a temperate climate with the ANAFORE model (ANAlysis of FORest Ecosystems) and compared the simulation results with sap flow measurements. The original model was expanded with a dynamic water flow and storage model that simulates sap flow dynamics in an individual tree. ANAFORE was able to accurately simulate diurnal patterns of measured sap flow under microclimatic conditions that differ from those of the calibration period. Strong relationships were found between stored water use and several tree characteristics (diameter at breast height, sapwood area, leaf area), but not with tree height. Relative to transpiration, stored water use varied over time (between < 1% and 44% of daily transpiration). On days when transpiration was high, trees were more dependent on stored water, indicating that the contribution of internal water to transpiration is not a constant in the water budget of trees.