Влияние микрорельефа и степени выгорания поверхности на водно-физические свойства торфяной залежи и характеристики химического состава вод постпирогенных болот Западной Сибири

The aim of this study was to examine the diurnal and seasonal variations in the sensitivity of leaf lamina (Klam) hydraulic conductance to irradiance in bur oak (Quercus macrocarpa Michx.) and trembling aspen (Populus tremuloides Michx.), which vary in their responses of Klam to irradiance. Klam was determined using the high-pressure method and the measurements were carried out in June, August and September. The irradiance response of Klam in bur oak was present throughout the day and declined in senescing leaves. In trembling aspen, Klam declined from morning to late afternoon and drastically decreased before the onset of leaf senescence, but it was not sensitive to irradiance. In both tree species, the capacity of the petioles to supply water to leaf lamina changed during the day in accordance with the ability of the leaf lamina to transport water. Petiole hydraulic conductivity (Kpet) declined during the season in bur oak leaves, while it tended to increase in trembling aspen leaves. There was no correlation between the Klam values and air temperature or light intensity at the time of leaf collection. For trembling aspen, Kpet was negatively correlated with the air temperature suggesting sensitivity to drought. We conclude that the water transport properties of petioles and leaf lamina in the two studied tree species reflect their ecological adaptations. Trembling aspen leaves have high hydraulic conductivity and high stomatal conductance regardless of the irradiance level, consistent with the rapid growth and high demand for water. In contrast, the increased lamina hydraulic conductivity and stomatal conductance under high irradiance in bur oak trees reflect a water conservation strategy.

In-channel water treatment systems remove excess nutrients through biological, chemical, and physical processes associated with the hyporheic zone. However, the impact of surface and groundwater interactions on these treatment processes is poorly understood. This research aims to assess the influence of varying groundwater conditions (neutral, drainage water, and groundwater seepage) and different bed sediment hydraulic conductivities on nitrogen and phosphorus dynamics in in-channel treatment systems. A flume containing bed sediment was used to study changes in surface water quality under different groundwater and bed sediment conditions. Compared to inlet and outlet concentrations, dissolved reactive phosphorus (DRP) and ammoniacal nitrogen (NH4-N) levels in the surface water increased by 11–65% and 10–51%, respectively, while nitrate (NO3-N) concentrations decreased by 11% under groundwater seepage conditions. The increase in NH4-N was due to ammonification, while the decrease in NO3-N was due to denitrification and mixing and dilution with the groundwater. The upward groundwater flux through the bed sediment transported both DRP and NH4-N into the surface water. Low hydraulic (LH) conductivity sediment led to greater changes in nutrient concentration than high hydraulic (HH) conductivity sediment (DRP increased by 65% and NH4-N by 51% for LH, compared to 11% and 10% for HH, respectively). However, HH conductivity sediment led to greater variations in pH and Eh values. The findings could assist the design and monitoring of in-channel treatment systems where groundwater and surface water interact.

Bioretention systems are used to treat stormwater. Using coarser filter media than commonly recommended with high saturated hydraulic conductivities may increase annual runoff volume capture, facilitate smaller filters, less overflow and adaptation to cold winters. However, this may affect water quality treatment negatively. Therefore, we investigated total and dissolved metal treatment at three full scale bioretention systems with a coarse filter material and saturated hydraulic conductivities >1500mm/h in Malmö/Sweden. One bioretention system was designed with a coarse sand-based filter medium, another with coarse sand-based filter medium and a submerged zone and the third with a 50:50 mixture of coarse sand and pumice as filter medium. The study included 19 rain events, partly during winter season when road salt was applied. The results suggest that also filter media with high hydraulic conductivity can be an effective option when metal treatment is targeted. The two systems with coarse sand filter media treated total metals effectively with median removals >80% for Cu, Pb and Zn and median removals >35% for Ni and Cr. Dissolved metal treatment was variable reaching from effective treatment for dissolved Cu, Pb and Zn with median removals >60% to overall leaching of dissolved Cd, Ni and Cr. Applying a submerged zone did not showed benefits for total or dissolved metal removal. Further, treatment of total and partly dissolved metals was significantly impaired due to pumice addition of the filter media, discouraging pumice as a filter media amendment. Coarser filter materials could be recommended for sites with space limitations or when frozen ground is expected in winter. Further, they can generally reduce clogging risks and untreated overflows.

Electric-hydraulic conductivity correlation in fractured crystalline bedrock: Central Landfill, Rhode Island, USA

We sampled fish communities, water temperature, water chemistry, physical habitat, and catchment characteristics for 94 stream sites selected randomly throughout the Northern Lakes and Forests ecoregion and used those data to explicitly model reference conditions and assess ecological stream condition at each site via a regional normalization framework. The streams we sampled were first order through fourth order, and the catchments ranged from 0.9 to 458 km2. We developed multiple linear regression (MLR) models that predicted fish community metrics, water chemistry characteristics, and local physical habitat from catchment characteristics; we used these models to compare existing conditions with the conditions that would be expected based on the regression models. Our results indicated that the fish communities were relatively unimpaired because the catchment variables associated with human‐induced land use change were important in only 1 of the 10 fish metric models. Agricultural land use was a significant variable in the MLR equation for species of Lepomis (sunfish). Agricultural land use and urban land use were both significant variables in all of the MLR models predicting water chemistry variables; urban land use was a significant variable in the MLR model predicting the percent coverage of all instream cover types. Regional normalization indicated that none of the sites were impaired based on fish community attributes. However, our analysis based on water chemistry metrics indicated that 22– 35% of the sites were impaired and that, based on physical habitat, 6–14% of the sites were impaired. A comparison with other published studies of the ecoregion suggested that the regional normalization process correctly characterized stream condition.

Hydraulic conductivity tests were performed on geosynthetic clay liners (GCLs) exhumed from composite barriers (i.e., geomembrane over GCL) in four landfill covers using three dilute permeant waters: type II deionized water (DW), 0.01M CaCl2 (so called “standard water” (SW)), and a typical water having average characteristics of eluent from cover soils (“average water” (AW)). Depending on the exhumed state of the GCL, very different (up to four orders of magnitude) hydraulic conductivities were obtained with DW, AW, and SW. When macroscopic features were present in the GCL, similar hydraulic conductivities (1×10−9–2×10−7 m/s) were obtained with SW and AW, but lower hydraulic conductivities were obtained with DW (1×10−11–3×10−10 m/s). For GCLs without macroscopic features, much higher hydraulic conductivities were obtained with SW (1×10−9–2×10−7 m/s) than AW or DW (<2×10−11 m/s) if the exhumed GCL had lower water content (<46 %), whereas similar hydraulic conductivities (<5×10−11 m/s) were obtained with all three waters if the GCL had higher water content (>53 %). For GCLs with lower water contents, permeation with AW or DW had minimal effect on the composition of bound cations. In contrast, permeation with SW reduced the mole fraction of monovalent bound cations. These findings demonstrate that the chemistry of the permeant water can have a significant effect on the hydraulic conductivity of exhumed GCLs even when the permeant water is dilute. To simulate typical conditions, a solution containing 1.3 mM NaCl and 0.8 mM CaCl2 is recommended as the permeant water (73.8 mg of anhydrous NaCl and 87.0 mg of anhydrous CaCl2/L DW). A conservative assessment of hydraulic conductivity can be obtained using 0.3 mM NaCl and 1.9 mM CaCl2 (15.5 mg of anhydrous NaCl and 214.6 mg CaCl2/L DW).

Continuous cover management on peatland forests has gained interest in recent years, in part because the tree biomass with significant evapotranspiration capacity retained in selection cuttings could be used as a tool to optimize the site water table level (WTL) from both tree growth and environmental perspectives. This study reports WTL responses from six field trials established on fertile Norway-spruce-dominated drained peatland forests across Finland. At each site, replicates of different intensity selection cuttings (removing 17–74% of stand basal area) or clear-cut in parallel with intact control stands were established and monitored for WTL for 2–5 post-harvest years. Observed WTL rose after selection cuttings and the response increased with harvest intensity and depended on the reference WTL, i.e. larger responses were found during dry summers or in more southern location. Selection cuttings removing about 50% of stand basal area raised WTL typically by 15–40%. Using a process-based ecohydrological model, tested against data from the field trials, we show that the role of tree stand in controlling WTL clearly decreases along the latitudinal climate gradient in Finland. This suggests that the potential of controlling WTL using selection cuttings is more prominent in southern compared to northern Finland. Predictions with future climate (2070–2099) further indicated a general decrease of WTL and that the importance of the tree stand in controlling WTL will increase especially in northern Finland. The results overall thus suggest that selection cuttings can be used as a tool to control WTL in boreal drained peatland forests, and the potential is likely to increase in future climate.

Streambed hydraulic conductivity is of great importance in the analysis of stream‐aquifer interactions and stream ecosystems. We investigated streambed vertical hydraulic conductivity (Kv) with two connected depths in three rivers of Nebraska. Our results demonstrated that streambed Kv in the upper sediment layer was much higher than that in the sediment of the lower layer. We speculate that hyporheic processes can result in larger streambed Kv in the upper layer. Specifically, water exchange through upwelling and downwelling zones can lead to bigger pore spaces and a more unconsolidated structure of sediments in the upper layer. The upward movement of gas produced by redox processes can loosen the sediments and further enlarge pore spaces in the upper layers. Also, permeability can increase as a result of expanded pore spaces caused by invertebrate activities in the upper part of streambed. The higher Kv will likely enhance exchange processes between stream and sediments.

In this paper, we assessed long-term changes in water table level of the Great Vasyugan Mire, water chemistry and the removal of mineral and organic substances in the mire-river system in the taiga zone of Western Siberia under the conditions of forest reclamation, pyrogenic factor and climate change. In the drained area of the Great Vasyugan Mire, a significant decrease in water table levels and an increase in the amplitude of their fluctuations by 1.6 times were noted. The effect of the pyrogenic factor is expressed, on the contrary, in an increase in water table levels due to surface burnout. In the water of the drained part of the Great Vasyugan Mire, an increase in the concentrations of Са2+, Mg2+, Fetotal, Cl-, К+, Na+, Cl-, SО42–, NO3-, DOC was noted. An increase in the content of NH+4, Feобщ, Cl-, SO42-, NO-3, and DOC is observed in river waters. An indicator of the effect of the pyrogenic factor on the chemical composition is an increase in the pH value and the content of K+, Na+, SО42–, NО–3, HCО3– ions, as well as Са2+, Mg2+, Feобщ. In connection with the overgrowth of the ditches, the process of self-healing of the mire is observed, and backwater zones are formed near the ditches and the amplitude of level fluctuations increases, as a result, the chemical composition of the waters of the drained and natural areas of the Great Vasyugan Mire in certain periods has minimal differences. Studies have shown that the removal of mineral and organic substances from the drained area of the great Vasyugan Mire prevailed in the high-water year 2018 and amounted to 2054 tons, of which the removal of DOC was equal to 47% or 969 tons. In the future, climate change, an increase in air temperature and precipitation in the region are likely, will contribute to the removal of biogenic elements and organic substances from mires and increase their concentration in river waters.

Some anatomical characteristics in leaves relating to hydraulic conductance and stomatal conductance were examined in six temperate deciduous tree species. The fourth power of the radius of the conducting elements in xylem ( r 4) and the area of mesophyll and epidermal cells per unit length of leaf cross-section ( u ) were high in leaves with high hydraulic conductance (L). Stomatal conductance ( g s) and stomatal sensitivity to an increase in leaf water potential ( s i) correlated positively with the length of stomatal pore ( l ), but negatively with the guard cell width ( z ) and the length of the dorsal side of the guard cells ( l d). Stomatal sensitivity to a decrease in leaf water potential ( s d) correlated negatively with l and positively with z and l d. The anatomical characteristics associated with hydraulic conductance ( r 4 and u ) and those associated with stomatal conductance and sensitivity to changes of leaf water potential ( l , z and l d) were correlated. We conclude that hydraulic conductance may depend on anatomical characteristics of xylem, mesophyll and epidermis, and stomatal conductance and its sensitivity to changing water potential may depend on anatomical characteristics of stomata. The correlation of shoot hydraulic conductance with stomatal conductance and its sensitivity may be based largely on the correlation between the anatomical characteristics of the water conducting system and stomata in these trees.

Degradation by drainage threatens biodiversity and globally important peatland ecosystem functions such as long-term carbon sequestration in peat. Restoration aims at safeguarding peatland values by recovering natural hydrology. Long-term effects of drainage and subsequent restoration, especially related to within-site variation of water table level and pore water chemistry, are poorly known. We studied hydrological variation at 38 boreal Sphagnum peatland sites (pristine, drained and restored) in Finland. The average water table level was significantly lower at Drained than Pristine sites especially near the ditches. We also observed large pore water chemical differences between Drained and Pristine sites, such as higher DOC concentration at the sites drained several decades earlier. Furthermore, there were large differences in water chemistry between the samples collected from ditches and from the peat strips between the ditches. For example, the ditch water had apparently higher minerogenic influence, while DOC concentrations were highest in peat strips. The water table level was, on average, at the targeted level of Pristine sites at 5 years ago restored (Res 5) and 10 years ago restored (Res 10) sites. The Res 10 sites were more similar to the Pristine sites in water chemical composition than were the Drained sites. Water chemical differences between ditches and peat strips were smaller at the Res 5 and Res 10 than at Drained sites indicating, on average, successful decrease of drainage-induced within-site variation in water chemistry. Our results suggest more pronounced water table inclination towards the old ditches at Res 10 than at Res 5 sites. While this pattern may be an early warning sign for incomplete recovery of hydrology in long-term, we found no chemical evidence supporting this assumption yet. Our study suggests that restoration can result in significant recovery of peatland hydrology within 10 years, while some deviation from pristine hydrology is still typical. Restoration appears to have potential to reduce leaching of nutrients and DOC to downstream waters in the long term, but practitioners should be prepared for temporary increase of leaching of N and P for at least 5 years after restoration of boreal Sphagnum peatlands.

The effective removal of excess heavy metals from surface stormwater is an important environmental goal due to their potential toxicity to aquatic organisms. In-channel stormwater treatment systems (ICSTS) are often used to remove pollutants from stormwater-impacted streams. However, the impact of hydraulic conditions on treatment performance is not well characterised. This research investigates the impact of varying groundwater conditions and bed media hydraulic conductivity on the dynamics of aluminium (Al), copper (Cu), and zinc (Zn) in ICSTS. Experiments conducted in a 19-m flume with gravel, bed media, and surface water under seepage, drainage, and neutral groundwater conditions revealed significant variations in heavy metal retention and release. Under groundwater seepage, there was an average decrease of dissolved Zn in the outlet and an increase in both total and dissolved Cu (5% for Zn; 16% for Cu) when using high hydraulic conductivity media (HH). Low hydraulic conductivity media (LH) under seepage led to a greater increase of dissolved and total Zn and Cu (7% for Zn; 44%–56% for Cu). Under drainage conditions, there was a decrease in dissolved Zn and Cu loads (14% for Zn; 15%–18% for Cu) with HH media and greater variation in pH and redox potential (Eh). Drainage with LH media resulted in lower Zn loads (8%) and an increase in total and dissolved Cu loads (34%–65%). Lower Zn concentrations were also observed in the groundwater (25%–46% decrease) after draining through the bed media, while Cu increased around 200% but only when using LH media. Total aluminium increased in concentration and loads while dissolved Al decreased in all scenarios. This research highlights the importance of designing ICSTS that promote drainage and high hydraulic conductivity bed sediment to enhance metal retention. It also emphasises the need for ongoing monitoring and maintenance to prevent clogging, contaminant release, and long-term performance decline.

<p>Changes in surface runoff from permafrost thaw in mountain catchments can be estimated using numerical cryo-hydrogeology models. However, such models can be complex from a numerical standpoint due to the need to simulate transient thermo-hydrologic feedbacks in highly heterogenous geological settings. Models that also seek to quantify water movement and water-budget contributions from ground-ice thaw must further account for changes in water/ice saturation to continually estimate and update the physical properties that control heat and water transfer in the ground (i.e., thermal and hydraulic conductivity) during the model execution. This has important implications for permafrost hydrology modelling efforts in arid mountain watersheds like the High Andes, where water security is threatened by climate change and the role of permafrost in the hydrologic cycle is unclear.</p><p>In this contribution the coupled finite element codes TEMP/W and SEEP/W are used to illustrate ground thermal and hydrologic dynamics for different geological scenarios within a hypothetical mountain slope, characteristic of the High Andes at an altitude of up to 6000 m. The 3 km-long, two dimensional cross-sectional model was developed based on a simplified topography, and ground temperatures and climate data collected within the region. In the first scenario, a uniform hydraulic conductivity is applied to the full model domain. A second scenario simulates a case where the hydraulic conductivity of the ground in the upper 200 m is an order of magnitude higher than for the rest of the model (i.e., as in fractured bedrock or unconsolidated sediment). The scenarios were subjected to a 1,000-yr seasonally cyclic climate forcing, followed by 1,000 years of warming superimposed on inter-annual variability at an average warming rate of 4 deg/100 year.</p><p>Model experiments show that the applied variations in hydraulic conductivity support vastly different permafrost and ground ice-content distributions under identical climate forcing. Compared to the uniform hydraulic conductivity case, the scenario with high hydraulic conductivity upper layer produces an increase in the heterogeneity of ice-rich permafrost under the stable climate forcing, and a slightly accelerated rate of permafrost thaw under climate warming. Higher recharge and discharge fluxes across the model surface are also predicted for the high hydraulic conductivity scenario.</p><p>The divergence in the results is attributed to preferential flow paths that develop near the model surface in the higher hydraulic conductivity case, which in turn leads to increased spatial complexity in advective heat transfer. This can have profound effects on predictive models aiming to estimate rates of permafrost thaw and discharge behaviour under climate warming, and highlights the need for awareness of uncertainties associated with estimated or assumed thermal and hydrologic properties in modelling large mountain catchments.</p>

A design procedure is proposed to minimize water infiltration into landfills by optimizing the water diversion length of inclined covers with capillary barrier effect (CCBE). This design procedure is based on a conceptual, mathematical and numerical approach and aims at selecting materials and optimizing layer thickness. Selection among candidate materials is made based on their hydraulic conductivity functions and on a threshold infiltration rate imposed on the designer. The capillary break layer (CBL; bottom layer) is characterized by a weak capillarity, while the moisture retention layer (MRL; upper layer) is characterized by a compromise between strong capillarity and high hydraulic conductivity. The thickness of the CBL corresponds to the height where suction reaches its maximum value for a given infiltration rate. This height can be calculated using the Kisch [Géotechnique 9 (1959)] model. The optimal thickness of the MRL is determined by applying an adaptation of the Ross [Water Resources Research 26 (1990)] model. The results obtained using the proposed design procedure were compared to those obtained from numerical simulations performed using a finite element unsaturated seepage software. The procedure was applied for two cover systems; one where deinking by-products (DBP) were used as MRL and sand as CBL and another where sand was used as MRL and gravel as CBL. Using this procedure, it has been shown that an infiltration control system composed of thin layers of sand over gravel is highly efficient in terms of diversion length and that its efficiency can be enhanced by placing a hydraulic barrier – such as a layer of DBP – above the MRL.

Geosynthetic clay liners (GCLs) were exhumed from final covers with composite barriers (geomembrane over GCL) at two municipal solid waste landfills in the USA. Preferential flow and high hydraulic conductivity (>2 × 10−9 m/s) was observed in eight of the 18 GCL samples collected from both sites. At one site, manganese oxide precipitate was concomitant with bundles of needle-punched fibers that conducted preferential flow. Nearly complete replacement of Na by Ca on the bentonite surface occurred in all GCL samples. GCLs with and without preferential flow could not be differentiated by physical and chemical properties commonly used to differentiate GCLs with high and low hydraulic conductivities (exhumed water content, swell index, mole fraction monovalent cations, soluble cation concentrations). The relative abundance of soluble cations in the pore water of GCLs exhibiting preferential flow was comparable to the relative abundance in the subgrade pore water, whereas the pore water in GCLs with distributed flow was more sodic than the pore water in the subgrade. Hydration experiments indicated that bentonite in GCLs initially hydrates in a zone surrounding bundles of needle-punching fibers. Cation exchange during this hydration process may create zones of higher hydraulic conductivity surrounding the fiber bundle, permitting preferential flow.