Fractionation of potentially toxic elements in urban soils from five European cities by means of a harmonised sequential extraction procedure

The revised (four-step) BCR sequential extraction procedure has been applied to fractionate the chromium, copper, iron, manganese, nickel, lead and zinc contents in urban soil samples from public-access areas in five European cities. A preliminary inter-laboratory comparison was conducted and showed that data obtained by different laboratories participating in the study were sufficiently harmonious for comparisons to be made between cities and land types (e.g. parks, roadside, riverbanks, etc.). Analyte recoveries by sequential extraction, with respect to direct aqua regia digestion, were generally acceptable (100 ± 15%). Iron, nickel and, at most sites, chromium were found mainly in association with the residual phase of the soil matrix. Copper was present in the reducible, oxidisable and residual fractions, whilst zinc was found in all four sequential extracts. Manganese was strongly associated with reducible material as, in some cities, was lead. This is of concern because high lead concentrations were present in some soils (>500 mg kg−1) and the potential exists for remobilisation under reducing conditions. As would be expected, extractable metal contents were generally highest in older, more heavily industrialised cities. Copper, lead and zinc showed marked (and often correlated) variations in concentrations between sites within the same city whereas manganese and, especially, iron, did not. No overall relationships were, however, found between analyte concentrations and land use, nor between analyte partitioning and land use

LEACHED SOILS IN SLOVENIA: PEDOLOGICAL PROPERTIES, SPATIAL DISTRIBUTION AND CLASSIFICATION

Eluvial-illuvial processes plays key role in pedogenesis, especially in the development of leached soils. As reported in Slovenian soil map 1 : 25.000 leached soils cover 2,3 % of Slovenian territory. They occur on different parent materials, mostly on flat relief preserved from erosion and colluvial processes. The aim of our study is the evaluation of their morpohological, physical and chemical properties, spatial distribution and dependency on soil forming factors, especially on parent material. Pedological properties are demonstrated according to analytical and descriptive data of 49 leached soils from the pedological base of Soil Information System of Slovenia. Obvious leaching processes are clearly recognized in almost all profiles of leached soils. Eluvial horizon in comparison to illuvial horizon has lower pH value, which is in average 4,4 and 4,6 for E and Bt horizon respectively, brighter color, lower base saturation (in average for 16,6 %) and lower CEC (in average for 5,5 mmolc 100 g -1 soil). On average ratio of clay content between illuvial and eluvial horizon is 1,63. In the 75 % of all studied leached soils this ratio is above 1,38. After evaluation, according to WRB classification, an argic horizon is identified only in 40 soil profiles, while other 9 profiles do not match criteria of sufficient textural differentiation or there is not enough data to classify them. Detailed overview of the WRB criteria for argic horizons (cation exchange capacity of clay fraction and base saturation in argic horizons) reveals that Luvisols and Alisols are the most widespread groups in Slovenia among leached soil. Against expectations based on different references, we do not determined Acrisols within Soil Map Database

Soil of the lower valley of the Dragonja river (Slovenia)

<p style="margin: 0cm 0cm 10pt;"><span style="line-height: 115%; font-family: 'TimesNewRomanPSMT','serif'; font-size: 9pt; mso-bidi-font-family: TimesNewRomanPSMT;">Soil of the lower valley of the river Dragonja developed under specific soil-forming factors. Soil development in the area was influenced by alluvial sediments originating from surrounding hills, mostly of flysch sequence rocks, as a parent material, Sub-Mediterranean climate and the vicinity of the sea. Different soil classification units (Gleysol and Fluvisol) were proposed for that soil in previous researches. The aim of our study was the evaluation of morphological, chemical and mineralogical characteristics of soil, based on detailed soil description and analyses, and to define the appropriate soil classification units. Field examinations revealed that the soil had a stable blocky or subangular structure and did not express substantial hydromorphic forms. Soil pH value was ranging from 6.9 to 7.5. In most locations electroconductivity (ECe) did not exceed 2 ds/m. Base saturation was high (up to 99 %), with a majority of Ca</span><span style="line-height: 115%; font-family: 'TimesNewRomanPSMT','serif'; font-size: 6pt; mso-bidi-font-family: TimesNewRomanPSMT;">2+ </span><span style="line-height: 115%; font-family: 'TimesNewRomanPSMT','serif'; font-size: 9pt; mso-bidi-font-family: TimesNewRomanPSMT;">ions. Exchangeable sodium percentage (ESP) was ranging from 0.2 to 3.8 %, which is higher compared to other Slovenian soils but does not pose a risk to soil structure. Soil has silty clay loam texture with up to 66 % of silt. Prevailing minerals were quartz, calcite and muscovite/illite. No presence of swelling clay mineral montmorillonite was detected. According to Slovenian soil classification, we classified the examined soil as alluvial soil. According to WRB soil classification, the soil was classified as Cambisol.</span></p

Vpliv začasne zasedbe kmetijskih zemljišč z deponijo gramoza ob gradbenih posegih na lastnosti tal

We addressed the condition of restored soil on alluvial plain in the south-eastern Slovenia after they have been given for the gravel deposit easement during construction. According to pre-investigation using soil probes, two soil profile pits were dug: Profile 1 on the area where excavated soils were deposited over original soilsand Profile 2 on the area where topsoil had been removed before gravel deposition and reapplied after the easement. Undisturbed and disturbed soil samples were collected and analyzed for physical and chemical properties. The results show that chemical properties were generally not the limiting factor for soil fertility. Compaction of the soil reduced hydraulic conductivity and resulted in water stagnation. The bulk density on the area where the material was deposited directly on the soil surface ranged from 1.41 to 1.77 g cm-3. The hydraulic conductivity of the saturated soil was practically impermeable at depths of 10, 20, and 30 cm, indicating compaction due to high mechanical load. At the area where topsoil was removed before deposition and restored after easement the hydraulic conductivity of the saturated soil was low to moderate. Removal of the topsoil before construction began was an appropriate action, but reclamation measures are also required

Eutric Cambisols – Slovenia’s best agricultural soils

This paper presents the main characteristics of Eutric Cambisols, their productivity potential expressed as land-rating, and their spatial distribution in Slovenia. Differences in soil properties were evaluated among the six predominant groups of Eutric Cambisols; classification was based on the parent material. In addition to individual characteristics affecting soil quality (texture, soil depth, amount of plant available water, pH, base saturation, cation exchange capacity), a comparison of land-rating values between the groups was also performed. We analysed 200 profiles excavated as part of the Slovenian Soil Mapping or other soil surveys conducted by the Center for Soil and Environmental Sciences, Biotechnical Faculty, University of Ljubljana. Our results show that Eutric Cambisols cover 15.5% of the area of Slovenia. Most Eutric Cambisols are on flysch (19.3%, 600 km²), followed by Eutric Cambisols on marl (12.7%, 398 km²). Eutric Cambisols on sandy gravel alluvial sediments, an important soil for crop production, cover 295 km² (9.4%). They have a favourable loamy texture and optimal pH. The flat terrain also contributes to this soil’s highest average weighted land-rating value (70 points). The average weighted land-rating value of all Eutric Cambisols is higher than the average weighted land-rating value of all agricultural and forest land in Slovenia, which is 36 points; this must be considered in spatial planning, as this type of land has a small share and above all, it must be protected from various degradations

Mineral composition, pedological characteristics and fractionation of selected chemical elements in soil of Maribor

The mineral composition, pedological characteristics and fractionation of selected chemical elements in the soil of Maribor were studied. The mineral composition reflects geological factors, especially the presence of igneous and metamorphic rocks in the surroundings of Maribor and in the Drava River catchment. Quartz prevails, followed by plagioclases, muscovite/illite, chlorite and dolomite. Potassium feldspar, amphiboles and calcite are also present in some samples. Relatively high pH values (6.9–7.4), high contents of plant-available phosphorous (13.5–185 mg/100 g of soil) and potassium in some samples reflect the anthropogenic influence on the pedological characteristics. The medians of the organic matter and carbonate contents are 8 % and 6.1 %, respectively. The majority of the samples belong to the sandy loam texture class, followed by loam class. Previous chemical analyses showed high contents of some potentially toxic elements (PTEs), especially Cu, Pb and Zn. We determined the fractionation of As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb and Zn using a sequential extraction procedure. All PTEs, except Mn, are mostly bound to organic matter and residual fraction soluble in aqua regia, meaning that they are relatively strongly bound to soil components. Arsenic, Co, Cr and Ni are particularly strongly bound. The contents in the first and second stage, which represent the most easily exchangeable fractions of PTEs, are negligible. The results indicate that the contents of studied PTEs in the soil of Maribor do not pose an environmental threat

Understanding the “acric” Illuvial soils in Slovenian soil classification in relation to Acrisols

The aim of our study was to clarify the use of the term “acric” in the Slovenian soil classification and its relation to the Acrisols of the World reference base for soil resources. A comprehensive review of Yugoslavian and Slovenian soil literature from 1960 to the present revealed that the term “acric” was first introduced into the classification of Yugoslav soils in 1973, based on FAO Legend (1968). “Acric” properties were most often associated with Illuvial soils (soils with argic horizons) of the Dinaric karst region. A detailed review and analysis of soil properties of 81 profiles with argic horizons from the Slovenian Soil Map database were done. Results clearly showed that soils with argic horizons are neither Acrisols nor Lixisols according to the latest WRB soil classification, as no soils with low activity clay in argic horizons have been proved so far. The base saturation and some recent measurements of effective base saturation indicate that Luvisols are the predominant Illuvial soils in Slovenia, with possible development to Alisols. Inconsistent use of the term “acric,” especially in the context of its translation to WRB reference group Acrisols, can lead to misunderstandings about the properties of such soils

Geochemical evidence of illuvial processes in clay-rich soils on limestones in a humid temperate climate

In environments with high precipitation, eluvial–illuvial processes play a key role in pedogenesis. Vertical translocation of clay leads to the formation of an argic horizon. Such soils are of global importance and formed on different rock substrates under different climatic conditions. However, the pedogenesis of clay-rich soils developed on limestone in humid temperate climates has not been sufficiently investigated. Therefore, this study aimed to evaluate the geochemical and mineral compositions and properties of Luvisols (10 profiles) from the Dinaric karst region and identify the geochemical indicators of eluvial–illuvial processes. The geochemical and mineral differences between the A, E, and Bt horizons could be explained by the pedogenic processes of biorecycling, migration, isomorphic substitution in minerals, surface adsorption to clay or Al/Fe oxide minerals, and precipitation from the soil solution. Illuviation is evident in the downward increase in Al2O3, Fe2O3, MgO, K2O, Ba, Co, Cr, Ga, Ni, Sc, Th, U, V, Y, and REE. Despite differences in the geochemical characteristics of the 10 studied profiles, eluvial–illuvial processes outweighed the heterogeneity of the soils from different sites and the probable contribution of allochthonous material to the soil. We established new textural and geochemical indicators that could explain the differences among horizons and profiles in light of the polygenetic origin of soil material and pedological processes

Historical overview of the use of the term acric in Slovenian soil classification

Pri poimenovanju in klasifikaciji tal se že vse od njenih začetkov soočamo z izzivi, ki izhajajo tako iz vpeljave tujih neznanih izrazov kot iz sprememb diagnostičnih meril in analitskih postopkov, s katerimi jih preverjamo. Pri prevajanju imen pedosistematskih enot Pedološke karte Slovenije (1 : 25.000) za namen mednarodnih publikacij in zemljevida tal Evrope, smo zasledili težave pri razumevanju akričnih tal. Akrična tla so v Pedološki karti opredeljena kot zelo kisla tla, z deležem bazičnih kationov na sorptivnem kompleksu tal manj kot 35% in sodijo med izprana tla. Merilo klasifikacije WRB za akričnost (qualifier acric) je majhna kationska izmenjalna kapaciteta glinene frakcije tal (< 24cmolc kg$^{-1}$ gline) ob hkratnem efektivnem deležu bazičnih kationov pod 50%. Tla z argičnim horizontom in akričnimi lastnostmi se uvrščajo v referenčno skupino Acrisols. Izprana akrična tla so se prevajala kot Acrisols, kar ne drži po merilih klasifikacije WRB in je lahko zavajajoče, predvsem za tuje bralce, ki ne poznajo tal v Sloveniji in meril slovenske klasifikacije. V prispevku smo preučili zgodovino rabe izraza akričnost v slovenski pedološki literaturi in klasifikaciji tal ter s tem izrazom povezane diagnostične lastnosti in merila. Ugotovili smo, da je bil izraz akričnost uveden leta 1973 na podlagi legende pedološke karte FAO iz leta 1968. V različnih obdobjih so uporabljali različna merila (horizonti, lastnosti, analitske metode), ki se niso posodabljala z razvojem mednarodne klasifikacije WRB

From soil quality to soil ecosystem services

Kakovost tal lahko definiramo kot kontinuirano sposobnost tal za zagotavljanje ekosistemskih storitev (ES). Znanost o tleh prepoznava pet glavnih funkcij tal, ki zagotavljajo ES: (i) primarna produkcija, (ii) čiščenje in uravnavanje vode, (iii) skladiščenje ogljika in uravnavanje podnebja, (iv) biotska pestrost in zagotavljanje habitatov ter (v) zagotavljanje in kroženje hranil. ES ocenjujemo po naslednjih pristopih: (i) na podlagi kazalnikov, pri katerih ocene ES tal temeljijo na poenostavljenih približkih izbranih lastnosti tal(ii) na empiričnih povezavah med lastnostmi tal in funkcijami tal (statični pristop) in (iii) na podlagi modeliranja talnih procesov v času (dinamični pristop). Število modelov in orodij za ocenjevanje ES tal narašča, vendar pa je vprašljivo, v kolikšni meri se ocene približajo realni porazdelitvi in zastopanosti posamezne ES v prostoru. Nujni so kakovostni vhodni podatki o tleh, izbor robustnih kazalnikov kakovosti tal za ocenjevanje ES in nadaljnji razvoj modelov ter orodij za ocenjevanje funkcij tal in ES v smeri zmanjševanja negotovosti. Slovenija šele postavlja koncept ES tal, zato je namen prispevka na osnovi pregleda literature osvetliti razvoj konceptov in pristopov njihovega ocenjevanja v mednarodnem prostoru