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Lysimeter monitoring as assessment of the potential for revegetation to manage former iron industry settling ponds
Abstract
To assess the impact of metal-rich brownfields on groundwater quality, the fluxes in a Technosol developed on a former iron industry settling pond were studied. Intact soil monoliths (1m(2)×2m) were extracted and placed in lysimeters. Dynamics of fluxes of metals and solutes under varying vegetation cover were monitored over the course of four years. Soil hydraulic properties were also determined. Results showed that the Technosol has a high retention capacity for water and metals, in relation to its mineral components and resulting chemical and physical properties. As a consequence, metal fluxes were limited. However, soluble compounds, such as SO4(2-), were found at significant concentrations in the leachates. The presence of a dense and deeply-rooted vegetation cover limited water- and solute-fluxes by increasing evapotranspiration and water uptake, thereby reducing the risks of transfer of potentially toxic compounds to local groundwater sources. However, vegetation development may induce changes in soil chemical (e.g. pH, redox potential) and physical properties (e.g. structure), favoring metal mobilization and transport. Revegetation is a valuable management solution for former iron industry settling ponds, provided vegetation does not change soil physico-chemical conditions in the long term. Monitored natural attenuation is required.
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... The impact of compaction in these soils is greater than in natural soils because they already present a limited porosity (Grabosky et al., 2009). Furthermore, the backfill materials used may induce specific processes such as precipitation of carbonates that can narrow the pore size (Wissmeier and Barry, 2009;Yilmaz et al., 2013) and subsequently the water storage, exposing vegetation to water stress (Urban, 2013;Huot et al., 2015). ...
... K fs may be sensitive to the materials contained in Technosols. The K fs geometric mean of T soils was four times as high as that of Technosols constructed with a mixture of paper sludge (Séré et al., 2012) and two times that of Technosols composed of waste from the iron industry (Huot et al., 2015). In other cases, such as in Technosols containing rubble, K fs was highly variable, ranging from 5.6 to 66.7 µm s −1 ) (Scalenghe and Ferraris, 2009;Shuster et al., 2014;Yilmaz et al., 2018). ...
... To prevent run-off, the vegetation cover should be maintained in these areas. However, spatial planning should adapt the management to the properties of Technosols because the low available water content can expose plants to hydric stress (Huot et al., 2015;Urban, 2013). ...
In urban areas, episodes of extreme precipitation may generate run-off floods, but urban soils are seldom considered in spatial planning documents. Our aim was to assess the infiltration of vegetated urban soils and to identify the soil parameters affecting infiltration in order to explore the potential of these soils for run-off mitigation under a Mediterranean climate with extreme precipitation episodes. We compared vegetated soils in the “urban” zone of the Marseilles’ 16th district (France) either lying on former clay quarries or tile factories (T) or not (NT) and with different land-uses. We used a simplified method to measure field saturated hydraulic conductivity (Kfs), measured penetration resistance in the first 0.15 m (Qd) and analysed physico-chemical properties in the first horizon. Levels of run-off production were estimated according to Kfs and an adaptation of USDA Hydrologic Soil Groups. All soils were Technosols or Anthrosols regardless of their prior history. We found that land-use history influenced Kfs, with T soils and soils with current vegetated land-use younger than 13 years having lower Kfs than NT soils and soils with land-use older than 13 years. Soil organic matter content influenced Kfs positively when soils were young, while vegetation cover and penetration resistance (most of the soils had Qd > 2 MPa) had not a clear effect on Kfs. Overall, combining Kfs and soil depth, 14.3% of the T soils and 84.6% of the NT soils had low levels of run-off production. It is therefore recommended that 1) Technosols or Anthrosols should be characterised for their unique physico-chemical and physical properties but also for their land-use history, and 2) the infiltration of these soils should be considered in spatial planning documents.
... The discussion to follow is based on investigations of soils formed in different types of technogenic materials (e.g., construction debris, mine spoil, industrial sludge and ashes, excavated bedrock, stormwater sediments) reported in the literature and from the example of a Technosol developing on a former iron industry settling pond (blast furnace sludge) under forest cover and a temperate climate since ca. 60 years, as previously studied (Huot, 2013;Huot et al., 2013Huot et al., , 2014aHuot et al., , 2014bHuot et al., , 2015Lucisine et al., 2015;Cortet et al.). ...
... Leaching of soluble compounds (e.g., chlorides, sulfates, carbonates) driven by rainfall has often been documented in the first stages of weathering (e.g., Zikeli et al., 2002;Séré et al., 2010;Abel et al., 2014;Scholtus et al., 2009Scholtus et al., , 2014Huot et al., 2015;Santini and Fey, 2015). Mineral transformations are important indicators of the evolution of technogenic materials under environmental factors. ...
... However, the original mixture of technogenic constituents and related physicochemical conditions could favor processes that might usually take place in different climatic regions when occurring in natural soils (Séré, 2007). For instance, in temperate humid regions, anthropogenic gypsum from construction debris or industrial by-products is leached (e.g., Zikeli et al., 2002;Séré et al., 2010;Abel et al., 2014;Huot et al., 2015). This may lead to the accumulation of secondary gypsum in deeper layers, which is usually encountered in dry climatic conditions (Zikeli et al., 2005). ...
... Additionally, the study of Technosols -highly anthropized soils (IUSS, 2014) -was found to be very promising as they are submitted to a fast and intense pedogenesis (Huot et al., 2015a(Huot et al., , 2015bLeguédois et al., 2016). As a study model, they enable the monitoring of significant evolution of soil propertiesincluding soil porositywithin a short period of time (i.e. less than a decade) (Séré et al., 2010). ...
... Indeed by comparing soils within an anthropization gradienti.e. from the oldest to the youngestwith or without vegetation, evidences of changes of hydrodynamics have been highlighted. In a similar way, Huot et al. (2015aHuot et al. ( , 2015b used in situ lysimeters to bring to light changes in soil chemical and physical properties. And Scalenghe et al. (2016) brought to light mechanisms about soil organic matter evolution thanks to incubated microlysimeters. ...
Soil poral architecture controls soil functioning and is submitted to temporal changes. The monitoring of soil structure dynamics is complicated by inherent technical constraints in its measurement that are either punctual or complex. In this study, four soils, from a natural one to incrementally anthropized (including three Technosols: Spolic Toxic, Terric Transportic, Spolic Garbic Hydric), have been studied. Seven 2-m3 lysimetric columns have been setup to compare planted and non-planted treatments over 3 to 6 years. Data on the water balance and the hydrodynamics were continuously acquired. Differences were observed between the various soils as a function of their texture. The presence of vegetation also led to significant differences, especially in hot periods, between the vegetated and the bare soils treatments: the amount of water stored into the soil was up to 210 L m-2 higher for bare soil. Furthermore, the analysis of the “critical water storage capacity” highlighted differences in the hydrodynamics at two time scales. For vegetated soils, similar seasonal variations depending on the climatic conditions were observed for all soils, with higher SCRIT values in cold periods compared to hot periods (differences were up to 190 L m-2). These results were attributed to roots development over the climatic year that decreases water storage capacity and increases preferential flows. Besides, significant trend evolution was also observed but only for the youngest i.e. the most anthropized soils. Their total water storage capacity decreased down to 52%. It is possibly due to soil compaction, the increase of pore connectivity related to root development and the formation of organo-mineral associations. Our work promotes the association of monitored lysimeters as tool and the study of soils within a gradient of anthropization in order to describe a pedogenetic process like the dynamics of soil porosity.
... Leaching of soluble compounds (e.g., chlorides, sulfates, carbonates) driven by rainfall has often been documented in the first stages of weathering (e.g., Zikeli et al., 2002;Séré et al., 2010;Abel et al., 2014;Scholtus et al., 2009Scholtus et al., , 2014Huot et al., 2015;Santini and Fey, 2015). Mineral transformations are important indicators of the evolution of technogenic materials under environmental factors. ...
... However, the original mixture of technogenic constituents and related physico-chemical conditions could favor processes which might usually take place in different climatic regions when occurring in natural soils (Séré, 2007). For instance, in temperate humid regions, anthropogenic gypsum from construction debris or industrial by-products is leached (e.g., Zikeli et al., 2002;Séré et al., 2010;Abel et al., 2014;Huot et al., 2015). This may lead to the accumulation of secondary gypsum in deeper layers, which is usually encountered in dry climatic conditions (Zikeli et al., 2005). ...
Soils formed in technogenic parent materials are proliferating and their pedogenesis remains inadequately understood. Upon investigation of soils formed in various technogenic materials reported in the literature and of a Technosol developing on iron industry deposits, potential specificities of pedogenesis within technogenic materials are discussed. Analyses have shown that pedogenetic processes observed in these soils are similar to those occurring in natural soils. However, some particularities have been highlighted, such as the coexistence of processes rarely encountered simultaneously in natural environments or high rates of soil development during the first stages of weathering. Technogenic materials display highly diverse constituents, wide spatial variability, and temporal discontinuities as a result of human activities. These inherent features, in interaction with other soil-forming factors, may govern the pedogenesis by generating the following conditions: i) a high diversity of pedogenetic processes, including processes occurring usually in dissimilar climatic regions, ii) localized processes and distinct rates and orientations of soil development over short distance and iii) a succession and/or a superimposition of processes, constrained by the deposition of materials and human operations. This creates the potential for the simultaneity of processes coexisting rarely in natural soils developing in the same climatic region. These soils are likely to have a polycylic evolution and to evolve towards groups of soils other than Technosols, depending on the dominant processes. Further investigations of the processes and their potential interactions occurring in a larger range of soils formed in technogenic materials are required to better predict the evolution of these soils.
... Based on data from the Indonesian Ministry of Environment and Forestry (2020), Indonesia has a total mining concession area of 810,400 ha in 2019, 346,000 ha of which are forest areas. Open-pit mining of silica sand caused several negative impacts on the environment, i.e., vegetation cover loss, fauna and soil microbes decline, nutrient deficiency, soil acidification, and soil contamination with heavy metals, which are toxic for plant growth (Cristescu 2012;Huot 2015;Gastauer 2018;Diatin 2018;Syauqie 2019). ...
Bekti HS, Budi SW, Wibowo C. 2022. Arbuscular mycorrhizal fungi inoculum and soil ameliorants enhance the growth of Falcataria moluccana in revegetation of post-silica sand mining land in Sukabumi, Indonesia. Biodiversitas 23: 1181-1187. Open-pit mining of silica sand caused several negative impacts on the environment, especially inhibited plant growth. MycoSilvi is Arbuscular Mycorrhizal Fungi (AMF) inoculum enriched with Mycorrhizal Helper Bacteria (MHBs) which could increase plant growth and nutrient uptake in degraded soils. A ?eld experiment was conducted to study the growth response of F. moluccana (Miq.) Barneby & JW Grimes seedlings treated with MycoSilvi inoculation and soil ameliorants (lime and compost) in post-silica sand mining land. The experimental design used in this study was a completely randomized block design with a factorial scheme. The results showed that MycoSilvi inoculation combined with soil ameliorant significantly improved plant growth of F. moluccana and assisted plant survival within nine months after transplantation in the field. MycoSilvi inoculation and soil ameliorants also increased the number of bacteria in the soil rhizosphere compared with control treatment. This study indicated that revegetation with MycoSilvi inoculation and soil ameliorants could influence plant establishment and development of microbial soil communities in infertile soils, suggesting that it could be an effective method for further ecological rehabilitation in degraded land areas.
... In this way the global risk of pollution with mine waste is reduced (Pourrut et al., 2011, Teixera et al., 2011. Plants decrease the air dispersion, and their roots limit the transfer risk of polluters to other compartments of the ecosystem and also lower soil erosion (Hartley et al., 2012;Huot et al., 2015). Passive and active tehniques can be used for the phytoremediation of ponds and heap. ...
The objective of this study is to carry out a vegetation study at the Bozanta’s tailing pond, located 5 km away from Baia-Mare.Between 2016 and 2017, using the metric frame, the existing species were identified and the following phytocenothic and population indices were determined: presence, frequency, presence classes, and the average abundance-dominance. Soil samples were taken to perform the following physico-chemical analyses: pH, P, K, N, humus and heavy metals.The floral inventory shows the presence of six tree species, four species of and 30 herbaceous species. Eleven years after the pond closure, the surface is covered with: 30% vegetation coverage, 35% water gloss and the 35% difference is occupied by arid. The average abundance-dominant synthetic indicator showed that the highest coverage is found in Betula pendula, Salix caprea, and in the grass species, Phragmites australis.The results of physicochemical analyses of the substrate showed very wide ranges of pH and different amounts of phosphorus, potassium and humus, and low amounts of nitrogen. The presence and concentration of the following heavy metals were determined from three samples: Cd, Pb, Ni, Cr. In regards to lead and chromium level, the alert threshold has not been reached.
... These manufactured soils have specific physical and chemical characteristics along with potential toxicity problems (Leguédois et al., 2016). Technosols were shown to perform ecosystem services such as water regulation (Huot et al., 2015). The research on physical properties of soil plays a significant role for the evaluation of reclamation success (Dexter, 2004). ...
The simulation of moisture content in Nikopol manganese ore basin technosols was performed using the Penman-Monteith approach and evaluate the role of the dependence of soils surface albedo from the humidity in the intensity of evapotranspiration. The sod lithogenic soils on loess-like loam and pedozem were chosen as the objects of the investigation. The research was conducted during 2012–2014 years at the investigation station of the remediation within Nikopol manganese ore basin (city Pokrov, Ukraine). The evapotranspiration from the soil surface was calculated by means of Penman-Monteith equation. Root zone moisture depletion is evaluated as the difference between soil water content at field capacity (pF = 2.3) and actual soil water content. The Ks value which is a water stress factor equals 1.0 as long as soil water content is higher than readily available water. If soil water content is lower than readily available water, Ks decreases linearly from one to zero according to total available soil water consumed. The soil water balance is performed in ISAREG with a daily time. The evaluation of readily available water content was carried out based on Penman-Monteith model taking into account meteorological data, technosols water-physical properties and the dependence of soil surface albedo on soil humidity. The color of the surface of the sod-lithogenic soil on the loess-like loam varies from yellow (2.5Y 4/2) in wet condition to yellow-red (10YR 6/5) in the dry condition. Albedo of this soil depended on the humidity varies in the range 0.17–0.31. The surface color of the pedozem varies from very dark gray (10YR 3/1) in wet condition to light-gray (2.5YR 6/2) in the dry condition. Albedo of this soil depended on the humidity varies in the range 0.10–0.31. There is a linear relationship between the moisture content in the soil and albedo of the soil surface. Albedo changes along with the humidity are most significant in the sod-lithogenic soils on loess-like loams. This is confirmed by the greatest regression coefficient. Albedo changes along with the moisture content are least significant in the pedozem. The distributionі of this index for different teсhnosols are characterized by a high level of similarity of shape due to the fact that the overall climate factors are crucial in shaping the dynamics of moisture. The distributions can be most good represented as a complex mixture of normal distributions. It was found that water supplies monitoring before the start of the growing season can provide valuable information necessary for the selection of crops for cultivation in the current year. The results indicate the urgency of measures to save the winter rainfall on the fields.
... While soil contamination is rarely reversible (Siebielec et al., 2010), it is sometimes possible to use brownfields to produce non-alimentary crops for energy or textiles . In this way, the past industrial soils recover new functions and their imperviousness is reduced (Huot et al., 2015) . However, the costs associated with remediation of past pollution in brownfields can be an obstacle to their re- Among the many techniques used to create "green infrastructure" in urban areas, rooftop gardens are one. ...
This chapter of the IPBES Land Degradation and Restoration Assessment evaluates the effectiveness of current response strategies both for avoiding or mitigating land degradation and for restoring previously degraded lands. More specifically: it develops a framework to assess the effectiveness of existing interventions designed to avoid and reduce land degradation processes and to rehabilitate or restore various types of degraded lands (e.g., croplands, rangelands, forest lands, urban lands and wetlands) through the recovery of biodiversity, ecosystem structure and services; assesses how responses to land degradation and restoration vary according to site-specific characteristics, including the type and severity of degradation, underlying direct and indirect drivers, and effects on ecosystem services and quality of life; evaluates the effectiveness of various response options to direct drivers (e.g., better land management techniques, access to training) and indirect drivers (e.g., institutions, governance systems) of land degradation; examines the relative success of different institutional, governance and management response options to avoid, reduce and reverse land degradation across a range of economic, social, environmental, cultural, technical and political scenarios; and assesses different institutional, policy and governance responses to research and technology development.
... These manufactured soils have specific physical and chemical characteristics along with potential toxicity problems (Leguédois et al., 2016;Maltsev et al., 2017). Technosols were shown to perform ecosystem services such as water regulation (Huot et al., 2015). Research on physical properties of soil plays a significant role for the evaluation of reclamation success (Dexter, 2004). ...
The restoration of a stable and productive ecosystem after drastic disturbances to the natural environment due to mining and open-cast mining may be achieved by means of reclamation. Investigation of the hydrological budget of technosols is important task in developing adequate approaches to reclamation. Sod lithogenic soils on red-brown clay, on grey-green clay were chosen as the objects of the investigation. The simulation of moisture content in Nikopol Manganese Ore Basin technosols was performed using the Penman-Monteith approach and evaluated the role of the dependence of soils’ surface albedo on the humidity in the intensity of evapotranspiration. The research was conducted during 2013–2015 at the station for research on reclaimed land within the Nikopol Manganese Ore Basin (city Pokrov, Ukraine). The experimental area for the study of optimal modes of agricultural reclamation was created in 1968–1970. Precipitation in the investigated area was found to fall very unevenly in time. In 2013, the duration of the rainless period was 259 days, in 2014 – 264 days, in 2015 – 261 days. The maximum daily rainfall varies within 18–49 mm. There are significant interannual differences in the intensity of rainfall. The minimum total annual precipitation in 2014 was due to a decrease in atypical rainfall in late winter and early winter. The maximum annual rainfall in 2015 was caused by intense rainfall both in the spring and in mid-summer and late autumn. The average annual temperature was 11.1 ºC and the annual totals did not statistically significantly vary within the study period. The average wind speed and average atmospheric humidity are statistically significantly different from year to year. The technosols’ colour properties and surface albedo varied depending on the moisture content. There is a linear relationship between the moisture content in the soil and albedo of the soil surface. The evaluation of readily available water content was carried out based on the Penman-Monteith model taking into account meteorological data, the water-physical properties of the technosols and the dependence of soil surface albedo on soil humidity. The distribution of this index for different teсhnosols is characterized by a high level of similarity of shape due to the fact that the overall climate factors are crucial in shaping the dynamics of moisture. A complex mixture of normal distributions is the best model for representing the experimental data. The readily available water content distribution can best be represented as a mixture of two normal distributions. The relatively high moisture level is characterized for winter and spring periods. Water content in sod-lithogenic soils on red-brown clay over the period of research never reached the value of the permanent wilting point. In 2013, the period when the moisture content was less than the value of the permanent wilting point lasted 23 days, and in 2014 this period lasted 39 days. Thus, you can always expect the phenomenon of drought under typical climatic conditions for the technosols on grey-green clay. It was found that monitoring water supplies before the start of the growing season can provide valuable information necessary for the selection of crops for cultivation in the current year. The results indicate the urgency of measures to save the winter rainfall on the fields.
... Soil is a structurally porous and biologically active medium that fulfills a number of functions such as providing a habitat for organisms, climate regulation, cycling of elements and water purification. Soils contaminated by inorganic pollutants can lose some or all of these functions but they may also evolve under the influence of forcing factors such as climate, presence of organisms or human activity, and can spontaneously recover some functions when colonized by vegetation (Huot et al., 2015). Contaminated soils may contain large amounts of metals and metalloids whose fate is directly dependent on their evolution and function. ...
The thermal destruction of chemical munitions from World War I, on the site of “Place-à-Gaz”, induced intense local top soil contamination by arsenic and heavy metals. The heat treatment mineralized As from organoarsenic warfare agents, resulting in a singular mineral assemblage, composed of Zn, Cu and Fe arsenates and of an amorphous phase rich in Fe, As, Zn, Cu and Pb. The amorphous material was the principal carrier of As and metals in the central part of the site. The site undergoes environmental changes which may alter the stability of inorganic contaminants. To assess the impact of water saturation episodes and input of bioavailable organic matter on the biogeochemical cycles of metal(loid)s, a mesocosm study was conducted. Results showed that amorphous phase was instable in saturated conditions, and released contaminants in soil water. As previously observed on site, the most mobile contaminants were Zn and As. The addition of organic matter induced the immobilization of As by trapping of As V onto hydrous ferric oxides in the saturated soil. Microbial characterizations including counting, bacterial community structure, respiration, and determination of As IIIoxidizing activities were performed. Results showed that microorganisms actively contribute to the metabolisms of C and As.The addition of organic matter induced the increase of As III-oxidizing and As V-reducing microorganisms concentrations and modified the bacterial diversity. However, a negative effect of organic matter on the activity of As III oxidation was observed resulting in higher As III concentration in soil water. This study showed that the natural deposition of forest organic litter on the site, induced antagonist effects on the transfer of inorganic pollutants did not immobilize all the Zn and As and even contributed to As III transport to the surrounding environment. These results provide more information about the environmental impact of the Great War and more generally about the processes driving the behavior of metals/metalloids on polluted sites.
... Tove) at a density of 240 kg ha −1 . One replicate was studied, as previous studies demonstrated the validity of the hydrodynamic and vegetation development monitoring over a long period of time without replicates (Séré et al. 2012;Huot et al. 2015 Nine 0.480-m 3 lysimeters, along with three copies of three distinct constructed soils, were built at the Angers (France) Agrocampus in April 2013 and then subjected to atmospheric conditions (Fig. 2). The climate was temperate with a mean annual temperature of 12°C and a mean annual precipitation of 650 mm. ...
... Soils contaminated by inorganic pollutants can lose some or all of their functions but they may also evolve under the influence of forcing factors such as climate, presence of organisms or human activity, and can spontaneously recover some functions when colonized by vegetation (Huot et al., 2015). Contaminated soils may contain large amounts of metals and metalloids whose fate is directly dependent on their evolution and function. ...
A mesocosm study was conducted to assess the impact of water saturation episodes and of the input of bioavailable organic matter on the biogeochemical cycles of C and N, and on the behavior of metal(loid)s in a soil highly contaminated by the destruction of arsenical shells. An instrumented mesocosm was filled with contaminated soil taken from the "Place-à-Gaz" site. Four cycles of dry and wet periods of about one month were simulated for 276days. After two dry/wet cycles, organic litter sampled on the site was added above the topsoil. The nitrogen cycle was the most impacted by the wet/dry cycles, as evidenced by a denitrification microbial process in the saturated level. The concentrations of the two most mobile pollutants, Zn and As, in the soil water and in the mesocosm leachate were, respectively, in the 0.3-1.6mM and 20-110μM ranges. After 8months of experiment, about 83g·m(-3) of Zn and 3.5g·m(-3) of As were leached from the soil. These important quantities represent <1% of the solid stock of this contaminant. Dry/wet cycles had no major effect on Zn mobility. However, soil saturation induced the immobilization of As by trapping As V but enhanced As III mobility. These phenomena were amplified by the presence of bioavailable organic matter. The study showed that the natural deposition of forest organic litter allowed a part of the soil's biological function to be restored but did not immobilize all the Zn and As, and even contributed to transport of As III to the surrounding environment. The main hazard of this type of site, contaminated by organo-arsenic chemical weapons, is the constitution of a stock of As that may leach into the surrounding environment for several hundred years.
... Tove) at a density of 240 kg ha −1 . One replicate was studied, as previous studies demonstrated the validity of the hydrodynamic and vegetation development monitoring over a long period of time without replicates (Séré et al. 2012;Huot et al. 2015 Nine 0.480-m 3 lysimeters, along with three copies of three distinct constructed soils, were built at the Angers (France) Agrocampus in April 2013 and then subjected to atmospheric conditions (Fig. 2). The climate was temperate with a mean annual temperature of 12°C and a mean annual precipitation of 650 mm. ...
Purpose
The densification and expansion of urban areas will increase the streams of waste materials such as bricks, concrete and street sweeping waste. In parallel, green areas offer the potential to overcome many challenges that face growing/expanding cities but require the use of large amounts of natural resources such as natural topsoil and aggregates. In this work, various waste materials mixed with organic debris are tested for greening applications in urban environments as an alternative to the consumption of natural resources.
Materials and methods
Five combinations of artefacts were studied either as “growing material” (i.e. dedicated to plant growth) or “structural material” (as support for traffic). These constructed Technosols were studied in situ in lysimeters under two sets of contrasting climatic conditions at two sites in France (Angers, oceanic climate, and Homécourt semi-continental climate). They were planted with trees (Acer platanoides) and with ryegrass (Lolium perenne L.).
Results and discussion
Compared to natural soils, the constructed Technosols exhibited high porosities and highly saturated hydraulic conductivities (up to 0.76 m³ m⁻³, and to 34.74 cm h⁻¹, respectively). The physical properties–i.e. macroporosity and microporosity–of these artificial soils revealed high water supply for plants, with available soil water ranging from 0.5 to 2.9 mm cm⁻¹. Tree and ryegrass roots were able to grow in the entire soil volume available in the lysimeters. Organic matter nature and soil pH conditions appeared to be the main drivers of plant development.
Conclusions
Constructed Technosols are suitable for vegetation growth and constitute a valuable alternative to the consumption of natural arable earth for urban greening applications, e.g. gardens, parks, and tree lines. Furthermore, they can provide high levels of relevant ecosystem functions in cities such as water retention and infiltration, plant settlement, carbon sequestration and even biodiversity habitats.
... To determine future agronomic use, the following nutrients were measured: total nitrogen (total Kjeldahl nitrogen, nitrite and nitrate) in the soil, total phosphorus, total potassium and total carbon. The presence of high concentrations of nitrogen in the soil indicates a possible biological activity of the upper layers (Huot et al. 2015). Over time, the water-soluble compounds such as these nutrients, will be phased out due to leaching, vegetation cover and dynamics recharge the soil solution. ...
Construction of Technosols offers interesting alternatives to two current problems in the city of Vitoria- Gasteiz (Spain): waste recycling and degraded plot recovery. To evaluate the viability of their use, 6 types of Technosols were created by mixing four different byproducts from municipal waste treatment plants. The less than 40 mm size fraction material from the municipal construction and demolition waste treatment plant was used as the main ingredient, bio-stabilized material from the solid urban waste treatment plant mixed with triturated pruning was used as organic matter input, recycled bentonites and topsoil from the public plots of Vitoria-Gasteiz (Spain) completed the mixture. Mixes were prepared in triplicate and installed in 48 m2 cells along with another 4 control cells containing only one of the ingredients at the municipal landfill of Gardelegui. A monitoring program for different parameters on soil, eluates and natural leachates was established to test the Technosols’ capacity to sustain vegetation without negative impacts on the environment. The final objective is to test their ability to restore unused municipal plots. Results from the first year show that Technosols are a suitable option for degraded sites restoration and green infrastructure support. All controlled parameters on soil are within the limits set by autonomic legislation for land use as public park. The eluate analysis concludes for all studied parameters that all mixes would be classified by legislation as inert waste, except for the sulphate concentration (which exceeds the inert waste limit of 1 000 ppm), that currently would label the soil as non-hazardous. In the natural leachate analysis strongly basic pH values were present above 9.5, the limit allowed in Royal Decreet 849/1986, but acidified throughout the year moving towards neutrality, with final values between 7.31 and 7.51. Leachate from CDW30, TS15 and RB30 Technosols showed not allowed values with respect to sulfates and Fe during the last sampling, surpassing the limits of 2 mg/l and 2 000 mg/l respectively. All studied Technosols presented a low ecological potential risk (RI < 150) for heavy metals in soil and eluates.
Mining is one of the most essential economic activities. However, mining produces large volumes of waste. A prominent example is the potash industry, which generates millions of tons of tailings, approximately 90 % of which are comprised of sodium chloride. Precipitation events dissolve this sodium chloride and generate saline drainage. To minimize the amount of brine, the University of Kassel, in partnership with the Schmeisky environmental consultancy, is attempting to develop an evapotranspiration cover for potash tailings piles based on technosol application. To further the research in this field and to assess the drainage quality of technosols used for the evapotranspiration cover of mining tailings, one experiment with 8 nonweighing lysimeters was conducted above a potash tailings pile in Heringen, Germany. Lysimeters were filled with four different technosols composed of municipal solid waste incineration bottom ash and coal combustion residues. During three hydrological years, the drainage amount, pH and electrical conductivity were evaluated on a weekly basis. Monthly analyses included the concentrations of chloride, sodium, sulfate, calcium, potassium, nitrate, magnesium and ammonium, as well as chromium, nickel, zinc, copper, lead, cadmium, mercury and arsenic. Overall, it was observed that the pH of the drainage increased, whereas its electrical conductivity decreased due to the leaching of ions. Chemical elements generally decreased to lower limits for waste use. Moreover, higher ionic loads were verified in winter, and technosols with larger proportions of municipal solid waste incineration bottom ash presented higher total ionic loads during the evaluation time of the experiment.
Forest ecosystems can spontaneously establish themselves on former industrial sites contaminated by metals. The sustainable management of these sites by natural attenuation requires a better understanding of the relationships between soil biodiversity, metals and soil functioning in such ecosystems. In this context, a forest ecosystem growing on iron industry by-products containing potentially toxic metals as major elements was studied using a multiproxy approach including chemical soil properties, microstructure, meso- and macro-fauna. Fauna communities in the topsoil were characterized by a high abundance and taxonomic diversity, but also by an unusual predominance of epigeic and detritivorous species. Fauna community structures were partly explained by the presence not only of heavy metals (Zn, Cd), but also Fe and Mn, dominant metals in iron industry by-products. The uncommon structure of macrofauna communities could have effects on the soil functioning, such as limiting the incorporation and mixing of organic matter into the soil. Mesofauna communities contributed to the metal redistribution in the soil by integrating metals into organo-mineral associations. In terms of management, this study showed the feasibility of using natural attenuation to manage sites with high metal contents but low metal availability and favorable conditions for plant growth. However, the influence of soil biota on metal mobility and soil functioning needs to be further investigated in order to assess the sustainability of such management.
Smelter activities in the Lorraine region (North-East France) have lead to the creation of flotation ponds that were used to eliminate wastes, mainly slag. After industrial decline, some of these flotation ponds were colonized by vegetation and evolved to forest ecosystems. One of these old flotation ponds, situated in Pompey, close to Nancy (North-East France), was studied by collecting information on several physico-chemical and biological indicators. The main objective was to understand the biological functioning of this system, whose soil can be classified as a pure Technosol, characterised by a very complex stratified profile created by successive slag deposits. Soil is characterized by its apparent heterogeneity, but also its high agronomic fertility and particularly high metal contents. Holorganic horizons can vary from one to several centimetres. Macrofauna is characterized by a very low abundance of earthworms and a dominance of millipedes. Furthermore, whereas earthworms do accumulate metals, this is not the case for millipedes. Mesofauna is typical of a temperate forest system, dominated by Collembola. Soil organo-mineral associations showed a high proportion of faecal pellets from Oribatid mites, Isopods and Diplopods. Furthermore, Mn, which is highly associated to metals (especially Zn and Pb) seems to play an important role in organo-mineral associations, including bacteria. An organic fraction is also directly associated to Calcium, Pb and Cu. Vegetation presents a high diversity, with more than 70 species, with very low metal transfer to plants. Results from soil respirometry are typical from temperate forest ecosystems. All this information has been combined to propose a model for the biochemical functioning of a such Technosol.
The sustainable use and management of global soils is one of the greatest challenges for the future. In the urban ecosystem, soils play an essential role with their functions and ecosystem services. However, they are still poorly taken into consideration to enhance the sustainable development of urban ecosystems. This paper proposes a categorization of soils of urbanized areas, i.e., areas strongly affected by human activities, according to their ecosystem services. Focus is put first on ecosystem services provided by non-urban soils. Then, the characteristics and number of services provided by soil groups of urbanized areas and their importance are given for each soil group. Soils of urbanized areas are here defined as SUITMAs, because they include soils of urban, sensu stricto, industrial, traffic, mining, and military areas. This definition refers to a large number of soil types of strongly anthropized areas. SUITMAs were organized in four soil groups, i.e., (1) pseudo-natural soils, (2) vegetated engineered soils, (3) dumping site soils, and (4) sealed soils. For each soil group, examples for ecosystem services were given, evaluated, and ranked. This proposal contributes to foster the dialogue between urban spatial planning and soil scientists to improve both soil science in the city and recognition of SUITMAs regarding their role for the sustainable development of urban ecosystems and, in particular, to enhance multifunctional soils in urban areas.
Modelling of solute transport under transient flow conditions requires many input parameters, especially when using the nonequilibrium model. Most often, these parameters are not accurately measured but estimated by means of the inverse methods. Among different factors causing the nonuniqueness issues of estimated parameters, limited information content and correlations among parameters are the important ones. Therefore, it is necessary to evaluate these factors to better define optimisation approaches. In this study, sensitivity and estimability analysis were performed to evaluate sensitivity, estimability and correlations of parameters describing the equilibrium and nonequilibrium tracer transport in the field lysimeter. Estimability analysis was based on a sequential calculation algorithm of a sensitivity coefficient matrix. The comparison of estimability and sensitivity results indicated that estimability analysis is much more useful than sensitivity analysis. The former allows evaluation of the information content of the tracer breakthrough data and possible correlations among parameters. The estimability results indicated that the tracer breakthrough data contained limited information content for estimating the hydraulic and solute parameters in the nonequilibrium model. Furthermore, the high correlation between the first-order rate solute and water transfer coefficients was found based on those data. This study may be considered as warning for the use of tracer breakthrough data to investigate the nonequilibrium solute transport at the field lysimeter scale. This further suggests that additional data are required to increase the ability of estimating the hydraulic and solute parameters at the given experimental conditions.
Abstract
Purpose: The sustainable use and management of global soils is one of the greatest challenges for the future. In the urban ecosystem, soils play an essential role with their functions and ecosystem services. However, they are still poorly taken into consideration to enhance the sustainable development of urban ecosystems. This paper proposes a categorization of soils of urbanized areas, i.e., areas strongly affected by human activities, according to their ecosystem services.
Materials and methods : Focus is put first on ecosystem services provided by non-urban soils. Then, the characteristics and number of services provided by soil groups of urbanized areas and their importance are given for each soil group.
Results and discussion: Soils of urbanized areas are here defined as SUITMAs, because they include soils of urban, sensu stricto, industrial, traffic, mining, and military areas. This definition refers to a large number of soil types of strongly anthropized areas. SUITMAs were organized in four soil groups, i.e., (1) pseudo-natural soils, (2) vegetated engineered soils, (3) dumping
site soils, and (4) sealed soils. For each soil group, examples for ecosystem services were given, evaluated, and ranked.
Conclusions : This proposal contributes to foster the dialogue between urban spatial planning and soil scientists to improve both soil science in the city and recognition of SUITMAs regarding their role for the sustainable development of urban ecosystems and, in particular, to enhance multifunctional soils in urban areas.
Purpose
Technosols include soils dominated or strongly influenced by human-made materials. Similarly to natural soils, technogenic parent materials submitted to environmental factors undergo weathering and transformation processes. But the pedogenesis of Technosols remains little known. With this aim in view, a Technosol developing on purely technogenic materials resulting from an iron industry was thoroughly characterized in order to discuss the pedogenetic evolution of this Technosol using knowledge about the pedogenesis of natural soils.
Materials and methods
The studied site was a former settling pond where mainly sludge generated by wet cleaning of blast furnace fumes was dumped probably until the mid-twentieth century. Thereafter, the pond has been colonized by vegetation and is covered by a diversified forest. The soil was composed of contrasted layers. A 20-cm organic layer has developed at the surface. Samples were collected in the first 2 m which are under root influence. Elemental composition, agronomic parameters, mineralogy, as well as the physical and hydraulic properties of the soil materials were characterized.
Results and discussion
Some characteristics of the Technosol, e.g. elemental composition, mineralogy or profile stratification, resulted mainly from industrial processes. However, some properties of the Technosol can be compared with natural soils. Particularly, the presence of low periodic order minerals and physical and hydraulic properties were analogous to the properties of Andosols. However, alkaline pH and the carbonate contents made the Technosol closer to carbonated soils. Moreover, the presence of Mn oxides, high porosity and water retention were also encountered in Mn-bearing soils. Early pedogenic processes, e.g. development of organic surface layer and signs of mineral weathering, were observed. But transfers seemed to be rather limited and/or slow in the profile. However, the physical and chemical properties, e.g. high water retention and high pH, were rather favourable to element retention.
Conclusions
The evolution of the Technosol seems to be still limited in the profile, which could be explained by the high retention capacity of the soil. The presence of highly reactive mineral phases, such as low periodic order Mn oxides or allophane-like minerals, with high contents of carbonates is rarely encountered in the natural environment and may suggest an important potential for pedogenic evolution, which could be directed by the balance between the weathering processes of these phases.
Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (− 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r2 = 0.43 to 0.59). Our results suggested that beside considering average management induced changes in soil properties (e.g. cover crop introduction), a dynamic approach to hydrological modeling is required to capture over-seasonal (tillage driven) and short term (environmental driven) variability in hydraulic parameters.
The pectic nature of root mucilages suggests a hypothetical action of these substances on heavy metal flux into the root. In this study the existence of relations between heavy metals and root mucilages were verified and quantified. In order to obtain substantial amounts of pure root mucilages, two methods of collection were developed, using: (1) maize plants grown in the field and (2) hydroponic axenic cultures. The study of mucilage-metal binding was conducted using the dialysis method, which was developed in a previous work. Results show that root mucilages are able to bind metals. The importance of the binding depends on the nature of the cation, following the order Pb > Cu > Cd. These reactions could be due to exchange processes involving mucilage cations (Ca2+, Mg2+) and heavy metals. The role of mucilages on the retention of heavy metals in the rhizosphere is also discussed.
A new and relatively simple equation for the soil-water content-pressure head curve is described. The particular form of the equation enables one to derive closed-form analytical expressions for the relative hydraulic conductivity, when substituted in the predictive conductivity models of N. T. Burdine or Y. Mualem. The resulting expressions contain three independent parameters which may be obtained by fitting the proposed soil-water retention model to experimental data. Results obtained with the closed-form analytical expressions based on the Mualem theory are compared with observed hydraulic conductivity data for five soils with a wide range of hydraulic properties.
Modelling the water-flow in the vadose zone requires accurate hydraulic parameters
to be obtained at the relevant scale.Weighable lysimeters enable us to monitor hydraulic
data at an intermediate scale between lab and field scales and they can be used to optimise
these parameters. Parameter optimisation using inverse methods may be limited by the nonuniqueness
of the solution. In this contribution, an estimability method has been used to
assess the estimability of the van Genuchten–Mualem parameters, to evaluate the information
content of the data collected from a bare field lysimeter and to optimise the estimable
model parameters. Daily data were monitored from a 2 m3 lysimeter, filled with the soil of a
former coking plant: pressure heads and water contents were measured at three depths (50,
100, 150 cm), cumulative boundary water fluxes.Water-flow was represented using the onedimensional
single-porosity model implemented in HYDRUS-1D code. The estimability of
the 5 van Genuchten–Mualem hydraulic parameters and the information content of different
data were evaluated by sequentially calculating a sensitivity coefficient matrix. Optimisation
was achieved by the Levenberg-Marquardt algorithm. The estimability analysis revealed that
estimability of the soil hydraulic parameters, based on the combination of daily pressure
heads and water contents, was higher than those based on these data separately. In case of
2.4 being considered as a cut-off criterion for this study, all the parameters were considered
estimable from daily data in the decreasing order: θs, n, Ks, α, θr . Hydraulic parameters
were optimised in four scenarios: θs and n were estimated with reliability while α, Ks and
θr were uncertain. However, the narrow variations in measured data restricted parameter
optimisation.
Es wird ein kombiniertes Verfahren zur Messung der hydraulischen Leitfähigkeit vorgestellt. Durch die Verbindung des Verdunstungsverfahrens mit einem stationären Durchflußverfahren ist es möglich, die hydraulische Leitfähigkeit bis nahe Sättigung zu messen. Die Meßwerte beider Verfahren gehen ineinander über. Durch den Wechsel von Entwässerung und Wiederbefeuchtung bei der Durchflußmessung ist es möglich, hysterese Eigenschaften des Bodens im Saugspannungsbereich < 60 hPa zu quantifizieren. A combined procedure to quantify the unsaturated hydraulic conductivity is presented. It is possible to measure the hydraulic conductivity up to near saturation by combination of the evaporation method and a steady state flowing‐through procedure. The measured values of both procedures are comparable. The quantification of hysteresic properties in the suction range of less than 60 hPa of the soil is possible by means of the flowing‐through measurements.
This paper focuses on the relation between the structure of a constructed Technosol and its hydraulic characteristics during its early pedogenesis. The method is based on a 3-yr comparison of, on one hand, experimental measurements from an in situ gravitation lysimeter and, on the other hand, a modeling approach with HYDRUS-1D. The change of water flow patterns with time was described. It was consistent with previous results for constructed Technosol aggregation. Apart from seasonal variations, the specificity of the hydraulic functioning of the constructed Technosol was shown to be due to the nature of its technogenic parent materials. The in situ evolution of the hydrodynamics has been established and partly linked to external factors (climate, vegetation). The direct modeling and the optimization of the parameters over first a 3-yr period and then three 9-mo periods accurately represented global water flow trends at the pedon scale. However it failed to simulate precisely the main events, such as massive leachate outflow. An evolution with time of some of the hydraulic properties was shown, expressing the structuring of the soil. The existence of two distinct time-scales (slow and steady/fast and cyclic) of the evolution of hydraulic parameters was then formulated as a new hypothesis.
Life on Earth is sustained by a small volume of soil surrounding roots, called the rhizosphere. The soil is where most of the biodiversity on Earth exists, and the rhizosphere probably represents the most dynamic habitat on Earth; and certainly is the most important zone in terms of defining the quality and quantity of the Human terrestrial food resource. Despite its central importance to all life, we know very little about rhizosphere functioning, and have an extraordinary ignorance about how best we can manipulate it to our advantage. A major issue in research on rhizosphere processes is the intimate connection between the biology, physics and chemistry of the system which exhibits astonishing spatial and temporal heterogeneities. This review considers the unique biophysical and biogeochemical properties of the rhizosphere and draws some connections between them. Particular emphasis is put on how underlying processes affect rhizosphere ecology, to generate highly heterogeneous microenvironments. Rhiz
This paper focuses on the quantification of vegetation related water fluxes of forest stands in the temperate lowland of Flanders. The underlying reason of the research was to develop a methodology for assessing the impact of forests on the hydrological cycle in comparison to agriculture. The tested approach for calculating the water use by forests was based on the application of the soil water balance model WAVE. The study involved the collection of data from 14 forest stands, the calibration and validation of the WAVE model, and the comparison of the water use ( WU ) components ? transpiration, soil and interception evaporation ? between forest and cropland. For model calibration purposes simulated and measured time series of soil water content at different soil depths, period March 2000?August 2001, were compared. A multiple-site validation was conducted as well. Actual tree transpiration calculated with sap flow measurements in three forest stands gave similar results for two of the three stands of pine ( Pinus sylvestris L.), but WAVE overestimated the actual measured transpiration for a stand of poplar ( Populus sp.). A useful approach to compare the WU components of forest versus cropland is scenario analysis based on the validated WAVE model. The statistical Profile Analysis method was implemented to explore and analyse the simulated WU time series. With an average annual rainfall of 819 mm, the results reveal that forests in Flanders consume more water than agricultural crops. A 30 years average of 491 mm for 10 forests stands versus 398 mm for 10 cropped agricultural fields was derived. The WU components, on yearly basis, also differ between the two land use types (transpiration: 315 mm for forest and 261 mm for agricultural land use; soil evaporation: 47 mm and 131 mm, for forest and cropland, respectively). Forest canopy interception evaporation was estimated at 126 mm, while it was negligible for cropland.
Preferential flow may significantly affect the acceleration of contaminant transport, which can be described by the use of nonequilibrium models such as dual-porosity and dual-permeability models. Its modeling requires many parameters that are generally difficult to measure. The determination of the parameters in these nonequilibrium models from experimental measurements is a challenging task and is usually carried out using parameter optimization methods. In this study, prior to the identification process, an estimability analysis was carried out in order to determine the set of the most estimable parameters in the dual-porosity model from the available experimental data collected from the field lysimeter (pressure heads, water contents, cumulative percolation, and evaporation). The most estimable parameters were then identified, and the less estimable ones were fixed from previous studies, literature, or additional measures. The results obtained from the estimability analysis showed that five out of the eight parameters were estimable from the combination of daily pressure heads and water contents. The five estimable parameters were then identified using the Levenberg-Marquardt method implemented within one-dimensional finite-element model software. Saturated water contents in the mobile and immobile regions were impossible to estimate simultaneously due to their high correlation. When the water transfer coefficient was included in the identification procedure, the optimization results worsened due to its low estimability from pressure heads and water contents. Removing saturated water content in the immobile region and saturated hydraulic conductivity, which had a strong correlation with more estimable parameters, led to the improvement of the optimization results. As a result, the water transfer parameter was estimated with reliability.
To better understand formation, functioning and evolution of a Technosol developing on a former settling pond of iron industry under forest cover, organic matter (OM) of layers along the soil profile was investigated. Spectroscopic and molecular analyses of extractable OM gave information on OM origin and state of preservation. In the surface layer, OM fingerprints indicated fresh input from vegetation while they revealed well preserved anthropogenic compounds related to industrial processes in deeper layers. OM variability and distribution according to the layers recorded deposition cycles of industrial effluents into the pond. Thus, the Technosol can be considered as archives of past industrial activities. The preservation of anthropogenic OM could be connected with mineralogy, high metal contents and particular physical properties of the Technosol.
Preferential flow may significantly affect the acceleration of contaminant transport, which can be described by the use of nonequilibrium models such as dual-porosity and dual-permeability models. Its modeling requires many parameters that are generally difficult to measure. The determination of the parameters in these nonequilibrium models from experimental measurements is a challenging task and is usually carried out using parameter optimization methods. In this study, prior to the identification process, an estimability analysis was carried out in order to determine the set of the most estimable parameters in the dual-porosity model from the available experimental data collected from the field lysimeter (pressure heads, water contents, cumulative percolation, and evaporation). The most estimable parameters were then identified, and the less estimable ones were fixed from previous studies, literature, or additional measures. The results obtained from the estimability analysis showed that five out of the eight parameters were estimable from the combination of daily pressure heads and water contents. The five estimable parameters were then identified using the Levenberg-Marquardt method implemented within one-dimensional finite-element model software. Saturated water contents in the mobile and immobile regions were impossible to estimate simultaneously due to their high correlation. When the water transfer coefficient was included in the identification procedure, the optimization results worsened due to its low estimability from pressure heads and water contents. Removing saturated water content in the immobile region and saturated hydraulic conductivity, which had a strong correlation with more estimable parameters, led to the improvement of the optimization results. As a result, the water transfer parameter was estimated with reliability.
Large surface areas covered with man-made materials are subject to pedogenetic evolution. However, pedogenetic processes in the resulting Technosols are seldom fully assessed. This work was conducted to identify and characterize the processes occurring on deposits of industrial technogenic materials. A former settling pond of the iron and steel industry where a forest has established since termination of the industrial activity approximately 50 years ago was chosen. A 2-m deep pit was opened, and a series of layers of the soil profile were sampled. The macro- and micro-structure were studied, and soil samples were analysed for structural, chemical and mineralogical assessment (chemical analyses, X-ray diffraction, infrared and Mössbauer spectroscopies, scanning and transmission electron microscopies coupled with energy dispersion spectrometry). Results showed that the profile was composed of a succession of sub-horizontal layers arranged in two groups according to their structure and composition, linked to the composition of the industrial effluent. Group 1 was composed of iron-, carbonate- and aluminosilicate-rich layers exhibiting a compact structure. Group 2 contained manganese-rich layers with a friable structure. Pedogenetic processes of various intensities were detected at different depths. Besides an accumulation of organic matter at the surface, transformations of minerals were recorded all along the soil profile, with weathering, leaching and precipitation of new phases. Phenomena occurred primarily in specific zones, such as cracks and interfaces between two layers. In conclusion, the soil maintained characteristics of the original industrial material and displayed several stages of pedogenesis, which were controlled chronologically by climatic and biological factors.
This work is based on a recent UK£1.25M restoration project of a contaminated canal and adjacent brownfield land. The canal sediment contained extremely high concentrations of heavy metals and arsenic whilst adjacent brownfield land presented localised hotspots. Potential receptor risks had been identified in the context of trace element mobility to groundwater and entrainment of dust particulates; the engineering work was initiated due to concerns that the sediment was drying and was likely to release contaminants through leaching as anoxic conditions were removed. Extensive engineering of the canal site involved its narrowing through dredging, relocation of the sediment to the edges but within the canal basin, cement stabilisation, retainment by geotextile-lined gabions, then coverage with geotextile and capping with recycled soil-forming materials including green waste compost (GWC). The adjacent brownfield land received import of GWC as a soil improver to enhance biological activity, although subsequent studies indicated contaminants were already stabilised in the soil and biological activity on the brownfield site was not suppressed. The data suggest that GWC should be applied with caution due to its influence on trace element mobilisation. In this paper we question whether real ecological improvements have been achieved and have justified the high cost of the restoration. We conclude that this case study does not provide a realistic template for best restoration practice of brownfield land. A better alternative to the whole site may have been a less-engineered, more-ecological approach through enhancing natural processes of regeneration, contaminant stabilisation and attenuation. Management of the canal site to maintain a wet anoxic sediment, rather than abandonment and dereliction would provide a more sensitive and less costly solution. Vegetation cover alone may be sufficient to mitigate risk on urban brownfield land.
In order to measure the pH at the soil-root interface (rhizosphere) of growing roots, 4 different plant species (maize, wheat, chickpea and white clover) were grown in plexiglass boxes in a soil of pH 6.0. Nitrogen was supplied at different rates and in different forms (nitrate, ammonium and N2 fixation, resp.). After a growth period between 4 and 10 days the soil and the roots were infiltrated with agar (35–38°C) containing bromocresol purple as pH indicator. The pH in the rhizosphere was also measured by microelectrodes inserted into the agar.
Compared to the bulk soil (pH 6.0) in the rhizosphere of maize plants the pH increased to about 7.5 with NO3--N and dropped to about 4.0 with NH4+-N as the N supply. However, with NO3--N striking pH differences were seen both along the roots and between the various root zones of the maize plants. In contrast to maize, the pH of the rhizosphere of chickpea seedlings decreased to about 4.5 even when supplied with NO3--N. In white clover the rhizosphere pH depended on whether nitrogen was supplied as NO3--N or via N2 fixation (i.e. rhizobial infection): with N3--N the rhizosphere pH increased to about 6.5 and with N2 fixation decreased to about 4.5. In mixed culture of maize and chickpea there were striking differences in pH values in the rhizosphere varying from 4.5 to 7.0.
The results demonstrate the extent to which the pH in the rhizosphere can differ from that further from the roots, depending on plant species and nitrogen source. The method described in this paper offers a simple way to obtain an overall view of this pH pattern in the rhizosphere of intact roots.
Parameters of functions to describe soil hydraulic properties are derived from measurements by means of parameter estimation. Of crucial importance here is the choice of correct constraints in the parameter space. Often, the parameters are mere shape parameters without physical meaning, giving flexibility to the model. A fundamental requirement is that the hydraulic functions are monotonic: the retention function and the conductivity function can only decrease as the capillary suction increases. A stricter physical requirement for the conductivity function is that its decrease with respect to saturation is at least linear. This linear decrease would occur if all pores of a capillary bundle had an equal radius. In the first part of this contribution, we derive constraints for the so-called tortuosity parameter of the Mualem conductivity model, which allow highest possible flexibility on one hand and guarantee physical consistency on the other hand. In combination with the retention functions of Brooks and Corey, van Genuchten, or Durner, such a constraint can be expressed as a function of the pore-size distribution parameters. In the second part, we show that a common modification of retention models, which is applied to reach zero water content at finite suction, can lead to the physically unrealistic case of increasing water content with increasing suction. We propose a solution for this problem by slightly modifying these models and introducing a correct parameter constraint.
Maintaining, and if possible increasing, soil fertility is a major goal for sustainable forest management, because it determines to a large extent the site's capacity for wood production. As, generally, forest soils are poor, and the demand for wood is still increasing, the boundary of resilience of each ecosystem must be known.Several cases must be identified: the case of natural or native species forests, either planted or not, which are extensively managed and the case of intensively managed plantations.In this paper, input–output budgets are calculated according to temporal and spatial scales. The measurement of the main inputs and outputs is discussed.When all the fluxes entering and leaving the selected compartment are measured, the budget provides a realistic picture of the direction of change in soil fertility. In other cases, the validity of the budget has to be considered according to the proposed hypothesis.A balanced budget means that the element considered is not depleted from the soil. This does not mean that no changes occur in the ecosystem. A positive budget means that the element considered is accumulating in the system, which is not always favorable. A negative budget means the element considered is depleted in the system, but it has to be related to the available soil reserves and to the rate of flux into available pool to be a real index of risk for the ecosystem.Information from several case studies shows the interest of these budgets because (i) they are able to characterize depletion before the direct analysis of the system would be able to indicate it, and (ii) they give useful quantitative data for recommendations applicable to forest management. These budgets have the disadvantage of being labor-intensive and expensive. They are also site-specific and give little direct information for identifying the mechanisms of nutrient tranformations within the ecosystem. The relationships between forest production and nutrient availability are not sufficiently known to be able to quantify the variation in production when nutrient depletion is observed.On account of the difficulty in calculating such a budget, the most efficient strategy could be the following: (i) calculate budgets in a representative network of sites; (ii) relate the individual budgets to more easily available parameters; and (iii) propose more simple indicators for managers. Land classification and the potential impact of forest management is required for giving appropriate recommendations to managers.
Carbonate leaching rates in several soils in Switzerland and in the Lake Constance region were calculated and related to landscape development. The leached depth of the soil, the carbonate content and the soil density profile are sensitive to soil age. A first database of carbonate leaching and its relationship to soil age is presented. A simple relationship between the amount of precipitation and carbonate losses was found. Water draining from calcareous soils from subarctic to temperate areas was usually close to equilibrium with calcite and dolomite. Thus, the annual amount of rainfall and consequently the percolation are the most important factors in carbonate leaching. The influence of temperature is comparatively low. Carbonate dissolution rates amounted to approximately 1.7–3.0 mol m−2 year−1 if they are referred (normalised) to 1000 mm soil water fluxes. Soils on coarse parent material may have slightly lower carbonate dissolution rates in the order of approximately 1.7–2.2 mol m−2 year−1 (normalised to a 1000 mm output), while other sites with smaller grain sizes had slightly higher dissolution rates (2.2–3.0 mol m−2 year−1).
Purpose
For abandoned slag heaps, the spontaneous establishment of a vegetation cover is usually considered beneficial as it represents a means of phytostabilization. However, for slag containing heavy metals, such a vegetation cover has a potential long-term effect on the fate of the metals. The objective of this study was to investigate how the long-term spontaneous revegetation of a slag heap can affect the fractionation and the leachability of Cd, Zn, and Pb.
Materials and methods
Soils from two plots covered by either Armeria maritima or Agrostis tenuis and a bare plot soil were sampled from a slag heap from a zinc smelting plant and characterized. The Community Bureau of Reference (BCR) sequential extraction scheme was adopted to determine the metal pools. The leachability of Cd, Pb, and Zn was assessed by means of a leaching column experiment.
Results and discussion
Long-term presence of a plant cover increased the proportion of Zn in the most mobile fraction and Pb in the fraction bound to organic matter. Cd distribution was relatively unaffected. Overall, the metal leachability was enhanced in the revegetated soils, notably due to higher organic anion release. However, responses of metal behavior to revegetation depended on the established plant species. The highest leachability of Cd was found in the soil covered by Agrostis tenuis, while the highest leachability of both Zn and Pb was observed in the soil below Armeria maritima.
Conclusions
Any remediation strategy for metal-rich waste dumps by phytostabilization should take into careful consideration the potential long-term mobilization effect of plant establishment on heavy metals. We conclude that, when using pioneer plants for phytostabilization purposes, preference should be given to pseudo-metallophyte over hyperaccumulator species.
During the production of pig iron in a blast furnace, a Zn- and Pb-containing sludge is generated in the air pollution control system. This toxic waste can be landfilled after dewatering and pretreatment, which is very costly. The sludge particles contain large amounts of Fe and C that could be recycled in the furnace. However, the Zn content of the sludge is high, and the Zn input to the blast furnace must be limited, so Zn has to be removed. This paper describes a hydrometallurgical process whereby the sludge is leached under both acid (HCl) and oxidizing conditions. After the separation of the solids, which mainly contain C and Fe, from the leaching solution, the latter is passed through an anion exchanger to remove Zn and Pb and is recirculated to the reactor. Investigation of the leaching behavior showed that a pH below 1.5 and a redox potential above 650 mV are required to obtain high leaching efficiencies for Zn and Pb. Sequential extraction showed that the largest part of Zn and Pb is extracted in acid medium, whereas an additional 16−18% is extracted in oxidizing acid medium. XRD analysis showed that after acid leaching, Zn partially occurs as sfalerite and as Franklinite. Comparison of the leaching behavior of the sludge with that of sfalerite and Franklinite geochemical standards confirmed this and showed that sfalerite dissolves in acid oxidizing conditions, whereas the Franklinite does not. Calculations with the geochemical speciation program MINTEQA2 were compared with experimental results, and the process developed was tested in a pilot plant.
A simple analytic model is proposed which predicts the unsaturated
hydraulic conductivity curves by using the moisture content-capillary
head curve and the measured value of the hydraulic conductivity at
saturation. It is similar to the Childs and Collis-George (1950) model
but uses a modified assumption concerning the hydraulic conductivity of
the pore sequence in order to take into account the effect of the larger
pore section. A computational method is derived for the determination of
the residual water content and for the extrapolation of the water
content-capillary head curve as measured in a limited range. The
proposed model is compared with the existing practical models of
Averjanov (1950), Wyllie and Gardner (1958), and Millington and Quirk
(1961) on the basis of the measured data of 45 soils. It seems that the
new model is in better agreement with observations.
In order to prepare allophane and imogolite in the laboratory, solutions containing l–2× 10–3 M orthosilicic acid and 4–0.5 × 10–3 M A1C13 (SiO2/Al2O3 molar ratio; 0.5, 1.0, 2.0, 4.0 and 8.0) were heated at 95–100°C for 113 hours after addition of NaOH (NaOH/Al molar ratio; 1.0, 2.0, 2.8 and 3.0). Boehmite was found in the precipitates from all solutions with initial SiO2/Al2O3 ratios of 0.5. Imogolite was found with allophane II in the products from solutions with SiO2/Al2O3 ratios of 1.0 or greater and with NaOH/Al ratios of 2.8 or less (final pH 5.0), whereas allophane I was found in the precipitates from solutions with the same SiO2/Al2O3 ratios but with the NaOH/Al ratio of 3.0 (final pH = 5.0–6.3). The mode of formation, chemical composition, infrared spectra, electron micrographs, electron diffraction patterns and differential thermal analysis curves of synthetic imogolite and allophanes (I and II) were compared with those of their natural counterparts.
The adsorption of Zn2+, Pb2+, Cu2+, Co2+, and Cd2+ (M2+) by soils was measured at concentrations ranging from 10-7 to 10-2 M in 10-3 to 10-2 M CaCI2. Exchange between Ca2+ and M2+, and solubility products [M2+][OH−]2 indicate that M2+ is not precipitated as hydroxide but is adsorbed on cation-exchange sites. The proportion of selective adsorption sites with specified values of the selectivity coefficient calculated using Ca as reference ion, increased in the order montmorillonite < humus, kaolinite, < allophane. imogolite < halloysite, iron oxides. Raising the soil pH by Ca-saturation increased both the amount and affinity of adsorption. Selectivity of adsorption increased in the order Mg, Ca < Cd, Co < Zn < Cu, Pb, and the selectivity coefficient varied from < 1 to > 10 000. The formation of the coordination complexes of heavy metal with deprotonoted OH and COOH groups as ligands is suggested as a possible mechanism of selective adsorption.
Lead (Pb) from the traffic accumulates in roadside soils, which are usually vegetated to control erosion. Plants release soluble organic substances that bind Pb. Root macropores also create preferential pathways through which water can flow. Both these processes may enhance Pb mobility. We used large lysimeters to investigate the transport of Pb in a contaminated (445 mg Pb kg−1) soil under vegetation (Phacelia tanacetifolia). Despite the high soil pH (7.2), Pb leached into the drainage water during the 5-month experiment. The fast response of the system to intense rainfall events indicated the presence of preferential flow. By comparing Pb concentrations in filtered and unfiltered leachates, we found that Pb was leaching primarily on suspended material. An increase in Pb concentration in the leachate at the end of the experiment indicated the remobilization of Pb, possibly by decaying vegetation. We parameterized the dual-porosity MACRO model using the experimental results. The simple parameterization of MACRO used to simulate the Pb concentrations in the drainage water produced an overall model efficiency of 0.81: MACRO simulated the Pb concentrations well, but it failed to predict the observed increase of Pb in the leachate at the end of the experiment. The model gave the best prediction of Pb concentrations with a small partition coefficient (kd= 150 cm3 g−1). Long-term simulations of Pb mobility showed that for our specific conditions preferential flow was the main process determining the fate of Pb.
Lysimeters are valuable for studying the fate and transport of chemicals in soil. Large-scale field lysimeters are used to assess pesticide behaviour and radionuclide transport, and are assumed to represent natural field conditions better than laboratory columns. Field lysimeters are usually characterized by a free-draining lower boundary. As a result, the hydraulic gradient is disrupted, and leachate cannot be collected until the bottom of the lysimeter becomes saturated. We compared heterogeneously structured, free-drainage lysimeters and field soils with respect to water flow and solute transport. Numerical simulations were carried out in a two-dimensional heterogeneous sandy soil under unsaturated water flow conditions with the CHAIN_2D code. Three different soil structures (isotropic, horizontal, and vertical) were generated, and Miller–Miller similitude was used to scale the hydraulic properties of the soil. The results showed that ponding occurs at the bottom of the lysimeter for the three soil structures and that it occurred faster and was more pronounced with the vertical structure (preferential flow effect). Breakthrough curves of a conservative solute (bromide) showed that solutes are moving faster in the field than in the lysimeters. Fewer differences between lysimeters and field soils were found with the horizontal soil structure than with the isotropic and vertical structures.
The results of these field experiments illustrate that the use of plants for risk-management and remediation of contaminated
soils and groundwater clearly is promising. But, certainly in case of metal contamination, the long-term duration argues for
the incorporation in current practices of land use (agriculture, forestry,...) and landscape management.
Phytoremediation is an emerging technology for the remediation of mine tailings, a global problem for which conventional remediation
technologies are costly. There are two approaches to phytoremediation of mine tailings, phytoextraction and phytostabilization.
Phytoextraction involves translocation of heavy metals from mine tailings to the plant shoot biomass followed by plant harvest,
while phytostabilization focuses on establishing a vegetative cap that does not shoot accumulate metals but rather immobilizes
metals within the tailings. Phytoextraction is currently limited by low rates of metal removal which is a combination of low
biomass production and insufficiently high metal uptake into plant tissue. Phytostabilization is currently limited by a lack
of knowledge of the minimum amendments required (e.g., compost, irrigation) to support long-term plant establishment. This
review addresses both strategies within the context of two specific climate types: temperate and arid. In temperate environments,
mine tailings are a source of metal leachates and acid mine drainage that contaminate nearby waterways. Mine tailings in arid
regions are subject to eolian dispersion and water erosion. Examples of phytoremediation within each of these environments
are discussed. Current research suggests that phytoextraction, due to high implementation costs and long time frames, will
be limited to sites that have high land values and for which metal removal is required. Phytostabilization, due to lower costs
and easier implementation, will be a more commonly used approach. Complete restoration of mining sites is an unlikely outcome
for either approach.
Information is needed on the range of soil water contents for tillage. The objective of the work was to develop methods for the prediction of the soil water contents at which tillage may be done satisfactorily. Three water contents are considered: the lower (dry) limit, the optimum water content, and the upper (wet) limit. This paper makes a synthesis of published results from tillage and soil physics experiments and also includes some new experimental results. The effects of tillage are considered in relation to some “fixed points” including the lower plastic limit, field capacity and a new fixed point “the inflection point”. These considerations lead to methods for prediction of the lower (dry) tillage limit, the optimum water content, and the upper (wet) tillage limit in terms of the parameters of the van Genuchten equation for soil water retention. Predictions can be made in terms of soil composition through the use of pedotransfer functions for the parameters of the van Genuchten equation. The new methods will enable the effects of soil degradation and climate change on tillage work days to be estimated. The results are potentially mappable using geographic information systems.
Maintaining, and if possible increasing, soil fertility is a major goal for sustainable forest management, because it determines to a large extent the site's capacity for wood production. As, generally, forest soils are poor, and the demand for wood is still increasing, the boundary of resilience of each ecosystem must be known.Several cases must be identified: the case of natural or native species forests, either planted or not, which are extensively managed and the case of intensively managed plantations.In this paper, input–output budgets are calculated according to temporal and spatial scales. The measurement of the main inputs and outputs is discussed.When all the fluxes entering and leaving the selected compartment are measured, the budget provides a realistic picture of the direction of change in soil fertility. In other cases, the validity of the budget has to be considered according to the proposed hypothesis.A balanced budget means that the element considered is not depleted from the soil. This does not mean that no changes occur in the ecosystem. A positive budget means that the element considered is accumulating in the system, which is not always favorable. A negative budget means the element considered is depleted in the system, but it has to be related to the available soil reserves and to the rate of flux into available pool to be a real index of risk for the ecosystem.Information from several case studies shows the interest of these budgets because (i) they are able to characterize depletion before the direct analysis of the system would be able to indicate it, and (ii) they give useful quantitative data for recommendations applicable to forest management. These budgets have the disadvantage of being labor-intensive and expensive. They are also site-specific and give little direct information for identifying the mechanisms of nutrient tranformations within the ecosystem. The relationships between forest production and nutrient availability are not sufficiently known to be able to quantify the variation in production when nutrient depletion is observed.On account of the difficulty in calculating such a budget, the most efficient strategy could be the following: (i) calculate budgets in a representative network of sites; (ii) relate the individual budgets to more easily available parameters; and (iii) propose more simple indicators for managers. Land classification and the potential impact of forest management is required for giving appropriate recommendations to managers.
Evaporation experiments are commonly used to derive hydraulic properties of soils. In the simplified evaporation method, as proposed by Schindler [Schindler, U., 1980. Ein Schnellverfahren zur Messung der Wasserleitfähigkeit im teilgesättigten Boden an Stechzylinderproben. Arch. Acker- u. Pflanzenbau u. Bodenkd. Berlin 24, 1–7], the weight of a soil sample and pressure heads at two height levels are recorded at consecutive times. The evaluation of these measurements relies on linearization assumptions with respect to time, space and the water content–pressure head relationship. In this article, we investigate the errors that result from the linearization assumptions, and show how systematic and stochastic measurement errors affect the calculation of water retention and hydraulic conductivity data and the resulting fits of soil hydraulic functions. We find that linearization errors with respect to time are negligible if cubic Hermite splines are used for data interpolation. Linearizations in space lead to minor errors, even in the late stage of evaporation where strongly non-linear pressure head profiles emerge. A bias in the estimated retention function results from the negligence of a non-linear water content distribution in the sample at the begin of the evaporation process, and affects primarily coarse sands or soils with structured pore systems. This error can be avoided if an integral evaluation of the measurements is used. We introduce an applicable rejection criterion for unreliable hydraulic conductivity data near saturation, based on the error in the hydraulic gradient. Calibration errors of tensiometers lead to biased estimates of hydraulic properties in the wet range, whereas errors in tensiometer installation positions yield biases in the dry range. Random errors in data cause no significant bias, and parametric hydraulic functions can be estimated with small uncertainties, if water retention and conductivity functions are coupled and the underlying model structure is correct.
The depth at which plants are able to grow roots has important implications for the whole ecosystem hydrological balance, as well as for carbon and nutrient cycling. Here we summarize what we know about the maximum rooting depth of species belonging to the major terrestrial biomes. We found 290 observations of maximum rooting depth in the literature which covered 253 woody and herbaceous species. Maximum rooting depth ranged from 0.3 m for some tundra species to 68 m for Boscia albitrunca in the central Kalahari; 194 species had roots at least 2 m deep, 50 species had roots at a depth of 5 m or more, and 22 species had roots as deep as 10 m or more. The average for the globe was 4.6±0.5 m. Maximum rooting depth by biome was 2.0±0.3 m for boreal forest. 2.1±0.2 m for cropland, 9.5±2.4 m for desert, 5.2±0.8 m for sclerophyllous shrubland and forest, 3.9±0.4 m for temperate coniferous forest, 2.9±0.2 m for temperate deciduous forest, 2.6±0.2 m for temperate grassland, 3.7±0.5 m for tropical deciduous forest, 7.3±2.8 m for tropical evergreen forest, 15.0±5.4 m for tropical grassland/savanna, and 0.5±0.1 m for tundra. Grouping all the species across biomes (except croplands) by three basic functional groups: trees, shrubs, and herbaceous plants, the maximum rooting depth was 7.0±1.2 m for trees, 5.1±0.8 m for shrubs, and 2.6±0.1 m for herbaceous plants. These data show that deep root habits are quite common in woody and herbaceous species across most of the terrestrial biomes, far deeper than the traditional view has held up to now. This finding has important implications for a better understanding of ecosystem function and its application in developing ecosystem models.
This paper reviews the factors affecting trace metal behaviour in estuarine and riverine floodplain soils and sediments. Spatial occurrence of processes affecting metal mobility and availability in floodplains are largely determined by the topography. At the oxic-anoxic interface and in the anoxic layers of floodplain soils, especially redox-sensitive processes occur, which mainly result in the inclusion of metals in precipitates or the dissolution of metal-containing precipitates. Kinetics of these processes are of great importance for these soils as the location of the oxic-anoxic interface is subject to change due to fluctuating water table levels. Other important processes and factors affecting metal mobility in floodplain soils are adsorption/desorption processes, salinity, the presence of organic matter, sulphur and carbonates, pH and plant growth. Many authors report highly significant correlations between cation exchange capacity, clay or organic matter contents and metal contents in floodplain soils. Iron and manganese (hydr)oxides were found to be the main carriers for Cd, Zn and Ni under oxic conditions, whereas the organic fraction was most important for Cu. The mobility and availability of metals in a floodplain soil can be significantly reduced by the formation of metal sulphide precipitates under anoxic conditions. Ascending salinity in the flood water promotes metal desorption from the floodplain soil in the absence of sulphides, hence increases total metal concentrations in the water column. The net effect of the presence of organic matter can either be a decrease or an increase in metal mobility, whereas the presence of carbonates in calcareous floodplain soils or sediments constitutes an effective buffer against a pH decrease. Moreover, carbonates may also directly precipitate metals. Plants can affect the metal mobility in floodplain soils by oxidising their rhizosphere, taking up metals, excreting exudates and stimulating the activity of microbial symbionts in the rhizosphere.
During blast furnace operation, a cyanide-containing muddy waste referred to as blast furnace sludge is generated in large amounts. In Germany it was and is still common practice to pump this sludge into surface deposits. Depending on species, cyanide has very different toxicity. To this day there is no information about the type of cyanide occurring in blast furnace sludge deposits. In order to identify the type of cyanide we investigated by means of wet chemical and powder X-ray diffraction analyses 37 samples of three blast furnace deposits. Wet chemical results indicate that both the extremely toxic free cyanide (HCN and CN ) and toxic weak metal-cyanide complexes, for example [Zn(CN)4]2-, are not present in the sludge. By powder X-ray diffraction we identified the crystalline cyanide-containing compound potassium zinc hexacyanoferrate(II) nonahydrate, K2Zn3[Fe(CN)6]2 x 9H2O, as the cyanide-bearing compound. Our study is the first that identifies potassium zinc hexacyanoferrate(II) nonahydrate in the environment. As the iron-cyanide complex [Fe(CN)6] is not acutely toxic, any direct hazard comes from cyanide occurring in the investigated wastes. Under the predominant pH milieu of the sludge (pH about 8) the solubility of potassium zinc hexacyanoferrate(II) nonahydrate is low, thus minimizing the mobility of cyanide.
In this review of lysimeters, different aspects concerning soil-filling technique, lysimeter size and materials, and drainage-system type are discussed. The placement of lysimeters in the field is dealt with, as are other types of field measurements that can provide complementary information. Evaluations of various properties are based on the assumption that the lysimeters are to be used for estimating pesticide leaching. Guidelines for use in designing a suitable lysimeter experiment for this purpose are described, with special emphasis placed on using the results as a basis for pesticide registration. In this context, some general recommendations are identified. Concerning the lysimeter itself, stress is placed on the importance of using undisturbed soil monoliths. It is recommended that two soil types, i.e. sand and clay, be used and that the management practices carried out closely resemble normal farming practices. Further recommendations include weekly water sampling, two watering regimes, and use of the normal and double the normal application rate of pesticides.
Blast-furnace sludge is generated during the production of pig iron and is disposed of in the environment in large surface landfills. We investigated blast-furnace sludge samples of an abandoned landfill in order to determine its chemical and mineralogical nature and to evaluate some environmental hazards that may arise from this industrial waste. The mineralogical inventory, which was quantified by Rietveld refinement of XRD analyses using the fundamental-parameter approach, revealed that blast-furnace sludge is dominated by X-ray amorphous substances (with a mean of 590 g kg(-1)) including coke and (hydr)oxides of Fe, Si, Al, Zn, and Pb. Calcite (CaCO3) (136 g kg(-1)), dolomite (Ca,Mg[CO3]2) (14 g kg(-1)), quartz (SiO2) (55 g kg(-1)), kaolinite (Al2[OH]4Si2O5) (40 g kg(-1)), graphite (C) (27 g kg(-1)), and chemically not specified layered double hydroxides (28 g kg(-1)) were identified in almost all samples. Iron is present as magnetite (Fe3O4) (34 g kg(-1)), hematite (Fe2O3) (38 g kg(-1)), wuestite (FeO) (20 g kg(-1)) and alpha-iron (Fe0) (6 g kg(-1)). Chemically, blast-furnace sludge is dominated by C (190 g kg(-1)) and Fe (158 g kg(-1)) reflecting the process of pig-iron production. On the basis of total contents, environmentally problematic metals (including As) are Zn (32.6 g kg(-1)), Pb (10.3 g kg(-1)), Cd (81 mg kg(-1)), and As (129 mg kg(-1)). As the forested landfill is used by residents for leisure activities, the exposure assessment by pathway oral uptake of blast-furnace sludge particles by humans has to be critically evaluated, particularly as significant proportions of metals are acid-soluble. However, under the prevailing slightly alkaline pH values of the sludge (pH 7.6-9.2), the solubility of the metals is very low as indicated by low pore water concentrations. Currently, groundwater monitoring should be focused mainly on F- since the F- concentrations in the pore water of blast-furnace sludge are at high level (2.65-24.1 mg of F- L(-1)).
Formes de transfert des éléments solubles dans les eaux gravitaires d'une rendzine forestière
- Le Tacon
Le Tacon F. Formes de transfert des éléments solubles dans les eaux gravitaires d'une
rendzine forestière; PhD dissertation;1981.
World reference base for soil resources 2014
- IUSS Working Group WRB
Comparative analysis of the actual evapotranspiration of Flemish forest and cropland, using the soil water balance model WAVE
- Verstraeten