Lateral Water Research Articles

Evaluation of Groundwater Inflow into an Iron Mine Surrounded by an Imperfect Grout Curtain

Grout curtains are often used to manage lateral water inflow. However, grout curtains constructed in extremely fractured rocks are not very effective, which poses a challenge for mine drainage and mining operations. So, it is crucial to consider the curtain’s effectiveness when evaluating water inflow. Large-scale pumping tests and groundwater numerical simulation were used in this study to evaluate the water inflow at an iron mine surrounded by an imperfect grout curtain. The effectiveness of the curtain was determined by comparing the hydraulic differences on both sides of the curtain and flow fields at pre- and post-grouting stages and three preferential seepage paths were identified. Given the mine’s complex boundary conditions, the telescopic mesh refinement modeling method was used; regional and local models were established using FEFLOW. The predicted inflow due to the gap in the curtain was 13,880 m3/day, accounting for 37.1% of the total 37,340 m3/day of water that still flowed into the mine. Two countermeasures, surface curtain remediation and underground grouting, were used to decrease water inflow and restore mine productivity.

Implications of terrain resolution on modeling rainfall-triggered landslides using a TIN- based model

This study employs a distributed eco-hydrological-landslide model, the tRIBS-VEGGIE-Landslide, to evaluate the influence of terrain resolution on the hydro-geomorphological processes involved in slope stability analysis. The model implements a Triangulated Irregular Network (TIN) to describe the topography starting from a grid-DEM. Five grid-DEM resolutions of the case study basin, i.e., 10, 20, 30 and 70 m, are used to derive the corresponding TINs. The results show that using irregular meshes reduces the loss of accuracy with coarser resolutions in the derived slope distribution in comparison to slope distributions estimated from the original grid-based DEM. From a hydrological perspective, the impact of resolution on soil moisture patterns and on slope stability is significant mostly when lateral water exchanges are allowed. The degrading of resolution leads to a reduction of the predicted unstable areas, with respect to the highest resolution case, from about 15% (20 m) to more than 40% (70 m).

Water permeability evaluation of fault zone in underground coal mines

A large number of mine water inrush data show that a fault zone is often a good water inrush channel. The fault zone internal architecture is very complex. The fault zone exhibits commonly heterogeneous and anisotropic permeability. Water permeability evaluation of fault zones has always been a difficult problem for mine hydrogeologists. This paper presents a semiquantitative permeability evaluation method of mine fault zones based on fault sealing, which evaluates the fault zone overall and partial lateral and vertical water permeabilities. First, a simplified conceptual model of the fault zone is applied to analyze the effects of lithology juxtaposition, fault rock plugging, fracture closure and hydraulic fracturing on groundwater flow. Second, corresponding to the 4 above influence mechanisms, a total of 6 evaluation indexes are obtained, including the juxtaposition probability of aquifers, juxtaposition of aquifers and aquicludes, fault shale content (FSC), aquifer water pressure, plastic deformation index of mudstone, and fault rock plastic deformation index. Finally, the juxtaposition probability of aquifers is used to evaluate the overall lateral permeability, while the juxtaposition of aquifers and aquicludes and FSC are employed to evaluate the partial lateral permeability. The aquifer water pressure is analyzed to evaluate the overall vertical permeability, while the mudstone and fault rock plastic deformation indexes are adopted to evaluate the partial vertical permeability. The overall lateral and vertical permeability grades are high and low, respectively, and the partial lateral and vertical permeability grades include 5 grades ranging from very high to very low. The evaluation method in this paper is applied to evaluate the water permeability of the F1 normal fault in the Nantun coal mine. The F1 fault water permeability evaluation results are consistent with underground exposure and geophysical data, which verifies the feasibility and rationality of this method.

Study of counteracting the secondary flow in open channel bends

In terms of the importance of reducing the influences of curvature induced circulation secondary flow, several counteracting techniques/measures have been studied. Although the previous techniques have obtained good results yet, they involve fixed and permanent construction works in the channel. Most of the techniques have a negative impact on navigation, and may be damaged under extreme flow conditions. Therefore, the use of new technique has become very significant and must be studied. The aim of this paper to study a new technique as an indirect tool to counteract the impact of the secondary flow on the banks and bed at channel bends by re-distribution of the main flow velocity in the curved section through water jets. In a previous experiment, air bubbles are induced as a bubble screen (air media) with an appropriate velocity, through a porous tube placed near the outer bank in the sharply open channel bend 193°. In this paper, one of the previous experiments is modeled with the same shape and conditions, however, the induced air bubbles from the porous tube in the experiment are replaced by a water screen to act as a source of momentum. A numerical model FLUENT was implemented and a realizable K-ε turbulent model was used to scrutinize and predict the velocity pattern in the channel bend. The impact of the change in lateral water jets flow from the porous tube was also investigated and results presented and compared. The results revealed that the water screen technique contributes in reducing the downward movement of the secondary circulation, dragging the flow upward, leading to the distribution of the secondary circulation, and shifting the core of maximum downstream velocities away from the outer bank towards the inner bank at the junction of generated circulation. The results also showed that the water screen is able to counteract the effect of the main flow circulation cells provided that this secondary flow is not less than 20% of the main flow and the corresponding velocity is also not less than 40% of the main flow velocity.

COMPUTATIONAL METHODOLOGY TO ANALYZE THE EFFECT OF MASS TRANSFER RATE ON ATTENUATION OF LEAKED CARBON DIOXIDE IN SHALLOW AQUIFERS

Exsolution and re-dissolution of CO2 gas within heterogeneous porous media are investigated using experimental data and mathematical modeling. In a set of bench-scale experiments, water saturated with CO2 under a given pressure is injected into a 2-D water-saturated porous media system, causing CO2 gas to exsolve and migrate upwards. A layer of fine sand mimicking a heterogeneity within a shallow aquifer is present in the tank to study accumulation and trapping of exsolved CO2. Then, clean water is injected into the system and the accumulated CO2 dissolves back into the flowing water. Simulated exsolution and dissolution mass transfer processes are studied using both nearequilibrium and kinetic approaches and compared to experimental data under conditions that do and do not include lateral background water flow. The mathematical model is based on the mixed hybrid finite element method that allows for accurate simulation of both advection- and diffusion- dominated processes.

Future changes in the Dominant Source Layer of riparian lateral water fluxes in a subhumid Mediterranean catchment

The ‘Dominant Source Layer’ (DSL) is defined as the riparian zone (RZ) depth stratum that contributes the most to water and solute fluxes to streams. The concept can be used to explain timing and amount of matter transferred from RZs to streams in forest headwaters. Here, we investigated the potential impact of future climate changes on the long-term position of the DSL in a subhumid Mediterranean headwater catchment. We used the rainfall-runoff model PERSiST to simulate reference (1981–2000) and future (2081–2100) stream runoff. The latter were simulated using synthetic temperature, precipitation, and inter-event length scenarios in order to simulate possible effects of changes in temperature, rainfall amount, and rainfall event frequency and intensity. Simulated stream runoff was then used to estimate RZ groundwater tables and the proportion of lateral water flux at every depth in the riparian profile; and hence the DSL. Our simulations indicated that future changes in temperature and precipitation will have a similar impact on the long-term DSL position. Nearly all scenarios projected that, together with reductions in stream runoff and water exports, the DSL will move down in the future, by as much as ca. 30 cm. Shallow organic-rich layers in the RZ will only be hydrologically activated during sporadic, large rainfall episodes predicted for the most extreme inter-event length scenarios. Consequently, terrestrial organic matter inputs to streams will decrease, likely reducing catchment organic matter exports and stream dissolved organic carbon concentrations. This study highlights the importance of identifying vertical, hydrologically active layers in the RZ for a better understanding of the potential impact of future climate on lateral water transfer and their relationship with surface water quality and carbon cycling.

Characterization of European lampreys and fishes by their longitudinal and lateral distribution traits

This study aims to complement existing fish-based assessment approaches by classifying European lampreys and fish species according to their probability of occurrence in six different longitudinal river regions and five types of floodplain water bodies under unimpaired conditions. The main objective was to provide for the first time harmonized occurrence traits for European lampreys and fishes in both longitudinal and lateral dimensions of floodplain river systems in a Fish Region Index (FRI) and Floodplain Fish Index (FFI), respectively.Altogether 163 lamprey and fish species established in European rivers have been scored according to their longitudinal and lateral occurrence probabilities. The species-specific Fish Region and Floodplain Fish indices and their variances inform about species’ occurrence probabilities, dispersal traits and potential species inventories of different river regions and floodplain waters. The final scores allow identifying characteristic fish assemblages, i.e. a set of type-specific species for the different longitudinal river regions and lateral floodplain water bodies.The species-specific index values and variances serve to calculate summary metrics for the total fish assemblage (FRItotal and FFItotal) as macro-scale indicators for the deviation of the total fish assemblage from a reference state. The resulting index values indicate degradation as well as rehabilitation success at the level of fish assemblages, i.e. at an ecologically relevant macro-scale. Both species-specific and total assemblage indices are directly comparable among all biogeographic regions of Europe independent of the local species pool. As such, the indices serve as assemblage indicators for the fish-based assessment of the ecological status of water body types and river regions in floodplain river systems, which are required in particular for the assessment of large floodplain rivers.

Coupling of the CAS‐LSM Land‐Surface Model With the CAS‐FGOALS‐g3 Climate System Model

AbstractThe land‐surface model of the Chinese Academy of Sciences (CAS‐LSM), which includes lateral flow, water use, nitrogen discharge and river transport, soil freeze‐thaw front dynamics, and urban planning, was implemented in the Flexible Global Ocean‐Atmosphere‐Land System model, grid‐point version 3 (CAS‐FGOALS‐g3) to investigate the climatic effects of eco‐hydrological processes and human activities. Simulations were conducted using the land‐atmospheric component setup of CAS‐FGOALS‐g3 with given sea‐surface temperatures and sea‐ice distributions to assess its new capabilities. It was shown that anthropogenic groundwater use led to increased latent heat flux of about 20 W∙m−2 in three groundwater overexploitation areas: North India, northern China, and central United States. The groundwater lateral flow accompanied by this exploitation has led to deepening water table depth in these regions. The derived permafrost extent from the soil freeze‐thaw front (FTF) was comparable to observations, and the inclusion of FTF dynamics enabled simulations of seasonal variations in freeze‐thaw processes and related eco‐hydrological effects. Inclusion of riverine nitrogen transport and its joint implementation with the human activity scheme showed large dissolved inorganic nitrogen concentrations in major rivers around the globe, including western Europe, eastern China, and the U.S. Midwest, which were affected by nitrogen retention and surface water use during transport. The results suggest that the model is a useful tool for studying the effects of land‐surface processes on global climate, especially those influenced by human interventions.

ФОРМЫ МИГРАЦИИ НИКЕЛЯ И МЕДИ В УЛЬТРАПРЕСНЫХ ВОДАХ ЦЕНТРАЛЬНОЙ ЧАСТИ КОЛЬСКОГО РЕГИОНА

The article presents the waters study results, the composition of which is formed in various hydrogeochemical and ecological conditions. All investigated waters are ultrafresh: TDS of streams and springs does not exceed 30 mg/l, water of Lake Imandra at sampling points is 40 and 73 mg/l. All waters are calcium bicarbonate, but the lake’s waters have an increased content of sulfate ion, chloride ion, and especially sodium. This composition is due to the influence of wastewater from the Kola MMC. It is shown that the 7 km stream is mainly groundwater discharge; however, judging by the concentrations of heavy metals and aluminum, the lateral soil water runoff also takes part in the formation of the stream’s water composition. For all studied waters, the gross concentrations of Ni and Cu hardly change after filtration through a membrane filter with a pore size of 0.45 μm, that is, these metals migrate in a dissolved form (a combination of colloidal and truly dissolved forms). The similarity of the results of determining the migratory forms of Ni and Cu in ultra-fresh waters by experimental and calculation methods is shown. Therefore, according to the assessment of the ratio of suspended, colloidal and truly dissolved forms of copper and nickel based on the results of an experiment using filtration and equilibrium dialysis, in the waters under consideration, the truly dissolved form of migration of Ni and Cu is predominant. The application of physicochemical modeling using the HydroGeo software package made it possible to show that nickel migrates mainly in the form of the Ni2+ ion, and copper in combination with the organic ligands Cu(FА) and Cu(FА2)2-. In addition, it was found that with an increase in the pH value of waters, the proportion of complex compounds increases and the amount of simple ions Ni2+ and Cu2+ decreases

Rice Yield Related to Fertilizers Applied by Farmers on Two Areas of Marginal Peat Soil in Bengkulu Indonesia

The research was intended to identify amounts of fertilizers applied by small-scale farmers related to rice yield cultivated on marginal peat soils in irrigated paddy fields in Bengkulu. The study was conducted at two peat areas; Pekik Nyaring Village, Air Hitam irrigated rice fields in Central Bengkulu and Sumber Makmur Village, Air Manjuto irrigated areas, Mukomuko Bengkulu Province from June to September 2020. A combination of purposive, snowballing samples was used to find 65 farmers as key informants. Collected data and information about fertilizers applied by farmers for paddy cultivation. Multiple regression analysis was used to find cumulative and partial contribution and significance effect of the fertilizers applied to rice yields. The result showed that fertilizers applied by the farmers significantly increase rice yield but the fertilizers played not great portion and urea fertilizer gave the highest contribution. Rice yield harvested by farmers was lower compare to the average rice productivity in Bengkulu because the doses of fertilizers applied were lower than the recommend dose. Rice yield can be improved through increasing the fertilizers dose. Optimum dose of fertilizers applied should be 567 kg Urea ha-1, 323 kg SP-36 ha-1, 790 kg ha-1 or 912 kg NPK ha-1. High soil porosity and lateral water conductivity however may cause inefficiency of fertilizers applied in marginal peat soils because soluble nutrients in peat solution carried out the fertilizers from root zone by water flow.

Experimental Study of Rainfall Infiltration in an Analog Fracture‐matrix System

In this study, an experimental apparatus was developed to investigate unsaturated infiltration in an analog fracture‐matrix system. Fracture and adjacent matrix is simulated by sands with various particle sizes. Four rainfall infiltration experiments were performed on the analog fracture‐matrix system at a constant rainfall rate of 100 mm/h. The process of rainfall infiltration is measured by a combination method of tensiometers and quick moisture apparatus. The measured results reveal that fracture‐matrix interactions certainly exert influences on the hydraulic behaviour of unsaturated fractured matrix, and the fluid flow mainly infiltrates along the nonuniform paths within the matrix. Moreover, it is observed that the influences are greater when using a coarser sand to mimic the fracture. Specifically, the wetting phase in the matrix moves faster than that in the fracture; the fracture, therefore, acts as a vertical capillary barrier, but there exists lateral water exchange from the matrix to the fracture. Overall, this study has demonstrated the importance of fracture/matrix interactions, which should be considered when dealing with unsaturated flow through permeable matrices.

Reduce the intensity of siltation of bulk reservoirs for irrigation and hydropower purposes

The results of field studies to study the siltation of a reservoir and the dynamics of their siltation are presented. The article presents designs that allow reducing the amount of sediment entering the reservoir bowl. The structure will contain spillways located perpendicular to the bed of the supply channel, elements of connecting structures, a sediment storage facility, and a lateral water outlet to the sediment storage facility. The reservoir sediment has a mark below the bottom of the supply channel and above the maximum water level in the reservoir and a wall of large pebbles that act as a filter for residual turbid water in the channel. In the basin of the deposit storage, a road is provided for trucks and equipment to carry out its seasonal cleaning.

Falsification‐Oriented Signature‐Based Evaluation for Guiding the Development of Land Surface Models and the Enhancement of Observations

AbstractWe develop a novel framework for rigorously evaluating land surface models (LSMs) against observations by recognizing the asymmetry between verification‐ and falsification‐oriented approaches. The former approach cannot completely verify LSMs even though it exhausts every case of consistency between the model predictions and observations, whereas the latter only requires a single case of inconsistency to reveal that there must be something wrong. We argue that it is such an inconsistency that stimulates further development of the models and enhancement of the observations. We therefore propose a falsification‐oriented signature‐based evaluation framework to identify cases of inconsistency between model predictions and observations by extracting signatures based on a set of key assumptions. We apply this framework to evaluate an ensemble of simulations from the Noah‐MP LSM against observations over the continental United States under the three assumptions of water mass conservation, no lateral water flow, and a sufficiently long period of time. Regions showing inconsistencies between the Noah‐MP ensemble simulations and the observations are located in the western mountainous areas, the Yellowstone river basin, the lower Floridan aquifer, the Niobrara river basin at the north tip of the Ogallala aquifer, and the basins downstream of the Balcones fault zones in Texas. These regions coincide with the sites where both advances in theoretical modeling and new observational data (e.g., from the Critical Zone Observatories) have emerged.

A comparison of three model output statistics approaches for the bias correction of simulated soil moisture

AbstractErrors in the physics schemes and parameters of a land surface model can lead to large errors/bias in simulated soil moisture. In addition, large bias in simulated soil moisture may be caused by soil lateral water flow that is not described in a land surface model. In the present study, three model output statistics (MOS) approaches (a linear regression based MOS, a rescaling based MOS and a cumulative distribution function matching based MOS) are proposed to correct these biases and errors at stations that have soil moisture observations. Results show that the biases/errors in simulated soil moisture were significantly corrected by the three MOS approaches. The best performance was obtained for the linear regression MOS model consisting of four separate linear regression MOS models for different seasons throughout the year (MOS‐SN). However, for the linear regression MOS and the rescaling MOS, a few months' data may also be used for MOS correction when the same seasonal period is used for both model fitting and prediction. With respect to goodness of fit and performance, the linear regression MOS model is better than the rescaling MOS model, and the MOS‐SN is slightly better than the nonlinear cumulative distribution function matching approach. For sites where soil moisture observations are much shorter, or more intermittent, than meteorological observations, the linear regression MOS approaches can be used to reconstruct missing historic soil moisture data. All MOS approaches can also be used to correct the errors/bias in forecast soil moisture from weather or climate models at sites with soil moisture observations.

Controlled treatment of a high velocity anisotropic aquifer model contaminated by hexachlorocyclohexanes.

Xanthan gels were assessed to control the reductive dechlorination of hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs) in a strong permeability contrast and high velocity sedimentary aquifer. An alkaline degradation was selected because of the low cost of NaOH and Ca(OH)2. The rheology of alkaline xanthan gels and their ability to deliver alkalinity homogeneously, while maintaining the latter, were studied. Whereas the xanthan gels behaved like non-Newtonian shear-thinning fluids, alkalinity and Ca(OH)2 microparticles had detrimental effects, yet, the latter decreased with the shear-rate. Breakthrough curves for the NaOH and Ca(OH)2 in xanthan solutions, carried out in the lowest permeability soil (9.9μm2), demonstrated the excellent transmission of alkalinity, while moderate pressure gradients were applied. Injection velocities ranging from 1.8 to 3.8mh-1 are anticipated in the field, given the permeability range from 9.9 to 848.7μm2. Despite a permeability contrast of 8.7 in an anisotropic aquifer model, the NaOH and the Ca(OH)2 both in xanthan gels spread only 5- and 7-times faster in the higher permeability zone, demonstrating that the delivery was enhanced. Moreover, the alkaline gels which were injected into a high permeability layer under lateral water flow, showed a persistent blocking effect and longevity (timescale of weeks), in contrast to the alkaline solution in absence of xanthan. Kinetics of alkaline dechlorination carried out on the historically contaminated soil, using the Ca(OH)2 suspension in xanthan solution, showed that HCHs were converted in TCBs by dehydrodechlorination, whereas the latter were then degraded by reductive hydrogenolysis. Degradation kinetics were achieved within 30h for the major and most reactive fraction of HCHs.

Modeling Aquifer Flow Behavior in Low-Dip Edge-Water Drive Gas Reservoirs

Water encroachment from aquifers into hydrocarbon reservoirs plays a crucial role in water production and, consequently, in prediction of hydrocarbon field performance. In this regard, several analytical and numerical models have been introduced to calculate water influx. While many studies have been conducted on water influx calculations in hydrocarbon reservoirs, the authors were unable to find any previous study describing aquifer behavior in relation to low-dip reservoirs. In this study, we investigated aquifer behavior in this specific reservoir type from two perspectives: First, water encroachment mechanisms from an aquifer into a low-dip reservoir were assessed, using a numerical gridded approach. Second, we evaluated the validity of analytical and numerical models used in commercial reservoir simulators for low-dip, edge-water drive (LDEWD) reservoirs. We applied the findings of this study to a LDEWD in a heterogeneous carbonate gas reservoir in the Middle East. This was the first study to identify that the major water influx was from the outer corner of the reservoir in the low-dip, edge-water aquifer. We have referred to this phenomenon as outer corner water encroachment (OCWE). We also showed that commonly available analytical and numerical models could not capture either a precise water movement profile or the water influx volume for LDEWD aquifers. The simulation results from prediction models used with actual field data showed that lateral water movement from the outer corner of the reservoir (OCWE movement) was the main contributor to water encroachment and production—and that the vertical water coning phenomenon was not significant in heterogeneous carbonate reservoirs.

A Hybrid Approach Calculating Lateral Spreading Induced by Seismic Liquefaction

Liquefaction-induced lateral spreading has caused severe damages to the infrastructures. To predict the liquefaction-induced lateral spreading, a hybrid approach was proposed based on the Newmark sliding-block model. One-dimensional effective stress analysis based on the borehole investigation of the site was conducted to obtain the triggering time of liquefaction and acceleration time history. Shear wave velocity of the liquefiable soil was used to estimate the residual shear strength of liquefiable soil. The limit equilibrium analysis was conducted to determine the yield acceleration corresponding with the residual shear strength of liquefied soil. The liquefaction-induced lateral spreading was calculated based on the Newmark sliding-block model. A case study based on Wildlife Site Array during the 1987 Superstition Hills earthquake was conducted to evaluate the performance of the hybrid approach. The results showed that the hybrid approach was capable of predicting liquefaction-induced lateral spreading and the calculated lateral spreading was 1.5 times the observed displacement in terms of Wildlife Site Array. Numerical simulations with two other constitutive models of liquefiable sand were conducted in terms of effective stress analyses to reproduce the change of lateral spreading and excess pore water ratio over the dynamic time of Wildlife Site Array. Results of numerical simulations indicated that the lateral spreading varied with the triggering time of liquefaction when different constitutive models were used. The simulations using PM4sand and UBC3D-PLM constitutive models predicted 5.2 times and 4 times the observed lateral spreading, respectively. To obtain the site response, the motions recorded at and below the ground surface were analyzed using the Hilbert–Huang transform. The low-frequency content of the motion below the ground surface was amplified at the ground surface, and the liquefaction effect resulted in a shift of the frequency content. By comparing the response spectra of the entire ground surface motion and the ground surface motion from the beginning to the triggering time of liquefaction, the liquefaction effect at the site was confirmed.

Assessment of the spatial variability of apparent electrical conductivity in a tile drained catchment in Fensholt subcatchment, Jutland, Denmark for improved small-scale prediction of highly reducing areas

The implementation of a targeted, site-specific approach on reducing the nitrogen load from agriculture requires fine-scale assessment of soil heterogeneity. In this study, the soil heterogeneity was described through the spatial heterogeneity of the apparent electrical conductivity values (ECa) and its implications to the patterns of redox potential values (Eh) in an intensely tile drained agricultural area. Piezometers and platinum-tipped redox probes for water level and Eh measurements were installed in transects along the assumed subsurface lateral water flow direction at different depths overlying the tile drains. Water level and Eh were determined from February to August 2017. A statistical analysis of the average ECa and slope measurements of each transect showed that they could be classified into four operational soil combinations (SC): high ECa, low slope (SC-1), low ECa, low slope (SC-2), high ECa, high slope (SC-3), low ECa, high slope (SC-4). A significant correlation between the inverted electrical conductivity (EC) values, clay and soil organic carbon (SOC) content suggested that the EC correlates with clay content. The high clay percentage associated with high ECa is assumed to facilitate development of anoxic microsites which led to more reducing conditions. Due to the generally reducing conditions and higher occurrence of saturated piezometers, transects under SC-1 were considered to have the most potential for intense nitrate reduction. In a tile drained setting, classifications based on average ECa and slope values may be utilized as parameters for a simple mapping tool for improved fine scale prediction of potential hotspots for nitrate reduction.

Characteristics of sulfide bearing soil materials in peat extraction areas in N-Finland

Concern has been raised about the potential formation of acid sulfate soils and associated environmental problems related to peat extraction and, thus, peat, sediment and till characteristics of 15 well drained peat extraction fields were investigated in northern and northwestern Finland. The aim was to identify and characterize the occurrence/abundance of potential acid (hypersulfidic) and actual acid sulfate soil materials as well as metals with regards to their depositional environment (marine/non-marine), black schists and soil material properties. Sulfide-bearing marine sediments were commonly found; the highest contents and thickness of sulfide sediments were found in areas <50 m above the current sea level (a.c.s.l.), while the sulfide contents were relatively low in the mineral soil materials (mainly till) in the non-marine areas (>100 m a.c.s.l.). The highest content of sulfides in sediments was typically found just below the peat layer. The sulfides existed mostly as pyrite (up to 3.5 wt% S) but were occasionally also mixed with more reactive metastable sulfide (Fe:S ratio in the order of 1:1), which coincide with high Fe concentrations, indicating that an abundance of Fe2+ can diminish the rate of pyrite formation. Sediments contained very high amounts of potential acidity, but in-field oxidation of the sediments was very limited. Although the sulfur contents were much lower (max 0.3% S), several of the till samples still became acidic (pH < 4) upon oxidation, and contained, thus, some amounts of potential acidity due to a pore buffering capacity. Consequently, during peat extraction most of the acidity is still retained in sediments limiting environmental consequences and, thus, focus should be on appropriate management to prevent oxidation and leaching after peat extraction has been finished. Locally high Mn and Zn concentrations were found in the sediments in black schist areas, indicating that Zn and Mn have migrated with the ground water from the schists to the sediment layers. In several black schist areas, the peat layer contained high amounts of sulfides with a corresponding high potential acidity as well as elevated As, Pb and Zn. This indicates an upward transport of sulfur and some metals (As, Pb and Zn) through capillary rise and/or plant uptake and/or through lateral water transport from surrounding black schist affected soil material. Air pollution, i.e. atmospheric distribution, was most likely a source for high concentrations of Cd, Hg and Sr concentrations in the peat.

Performance of adhesive waterproofing as regardsof lateral water filtration

Performance of adhesive waterproofing as regardsof lateral water filtration