Proposal for a new reference group for the World Reference Base for Soil Resources (WRB) 2006: the Technosols 2 nd revised draft December 2, 2005

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1 Proposal for a new reference group for the World Reference Base for Soil Resources (WRB) 2006: the Technosols 2 nd revised draft December 2, 2005 D G Rossiter 1 Coördinator, Working group on Technosols, WRB International Institute for Geo-information Science & Earth Observation (ITC) P.O. Box 6, 7500AA Enschede, the Netherlands rossiter@itc.nl; web: Abstract This document proposes changes to the World Reference Base for Soil Resources (WRB) to better acommodate soils dominated by technic material. It is the second draft, aiming at the revision of the WRB to be submitted at the 2006 International Union of Soil Sciences (IUSS) meetings. Three new definitions are proposed: Artifacts are defined as solid or liquid material created by humans as part of an industrial or artisanal manufacturing process and found in the soil. Technic soil material is defined as material dominated by artifacts and having properties substantially different from those of natural soil materials, and recognizable as such in the soil. Human-transported soil material is defined as material moved into a pedon from a source area outside of its immediate vincinity by intentional human activity, and recognizable as such in the soil. Technosols is proposed as a new reference group, whose central concept is soils whose properties and pedogenesis are dominated by technic material or their origin as human-transported material. It also includes pavements underlain by unconsolidated material, as well as soils with a continuous impermeable constructed liner. The Technosols are to follow the Histosols and Anthrosols in the key to reference groups. Organic soils which otherwise qualify as Technosols are excluded from the Histosols. Soils from technic materials which otherwise would qualify as Anthrosols are likewise excluded from the Anthrosols and classified as Technosols. A list of qualifiers for Technosols is proposed. The first priority group of prefix qualifiers indicates how the soil qualified as a Technosol in the key: Ekranic (pavements), Lined, Technic or Spolic. This also serves as a sub-division of the Technosols Other prefix qualifiers are intergrades in key order, including (among others) Histic, Anthric, Hyperskeletic, Fluvic, Vitric, Andic and Hyperarenic. Suffix qualifiers are proposed for other characteristics which influence soil behaviour or where pedogenetic horizons have developed. Technic and Spolic suffix qualifiers are proposed for other groups where there is insufficient technic or human-transported material to qualify as Technosols but enough to influence soil behaviour. Compactic and various -toxic phases for contaminated soils are proposed, applicable to all groups. 1

2 Contents 1 Introduction 3 2 What is the soil we classify in the WRB? 4 3 The Technosols concept 5 4 Definitions Natural, artificial, technic Artifacts Human-transported material Technic soil material Technic hard rock The Technosols Reference Group Placement in the key Qualifiers for Technosols Prefix qualifiers (1): placement in Technosols Prefix qualifiers (2): integrades Suffix qualifiers Phase qualifiers The Technic and Spolic qualifiers for other reference groups Changes to current definitions References 15 2

3 1 Introduction The WRB The objectives of international soil classification are, first, to allow exchange of scientific knowledge of soil behaviour and properties and, second, to provide names for soilscape units at medium and small scales, especially for maps covering a region or continent. The World Reference Base for Soil Resources (WRB) (WRB) [8, 5] is the international soil classification system recognized by the International Union of Soil Sciences (IUSS), and hence by the International Council of Scientific Unions (ICSU). These objectives are as important in urban and industrial as in rural areas, yet the WRB, in common with most soil classifications, was based on a great deal of experience with agricultural, rangeland and forest soils, with scant attention to areas with intense human influence. The WRB is intended to be used to classify soil individuals ( pedons ) and correlate names for these in national and local soil classification systems, to a medium level of detail, roughly equivalent to Soil Taxonomy [19] subgroups. Much detail of practical importance, including substrates ( parent material ), detailed horizon sequences and thicknesses, and narrower limits for diagnostic features can be addressed in local or national systems. Thus, multiple local names will be correlated to a single WRB name. The WRB is also intended to be used as a map legend for small- and medium-scale soil maps [4, 4], up to 1: with prefix qualifiers and to 1: with full qualifiers. National or local soil classification systems must be used at larger mapping scales; in addition, mapping phases must be used for landform or use; these are not considered attributes of the soil itself. Objective of this document This paper proposes modifications to the WRB which, while respecting its purpose and structure, improve the classification of urban and industrial soils, in particular soils dominated by technical materials or extreme human interference. It is assumed that the reader is familiar with the current WRB, its objectives and classification principles. This paper follows the draft Proposal: Classification of urban and industrial soils in the WRB of 29- November This second version is still a working document for comments by all interested parties. Comments are solicited and should be directed to the author, who will attempt to harmonise them and revise this proposal accordingly. The WRB leadership will consider the final proposal and may itself alter it in line with concurrent revisions proposed by other working groups (in particular the Anthrosols group headed by Zhang Gan-lin). This document focuses exclusively on the definition of a new reference group, the Technosols. Many other issues in urban soil classification are ignored here, but were mentioned in the earlier draft. Previous work The present proposal owes much to recent activity in the classification of humaninfluenced and urban soils, especially at the SUITMA 2001 and 2003 [e.g. 18, 17] meetings, at international soil classification meetings in 2001 [e.g. 22] and 2004 [21], and by national working groups, e.g. in Germany [2]. At the 2004 international meeting a session was dedicated to the so-called Technosols, which were conceptually defined as human-transported and technic soils and separated from the Anthrosols 1. A wide-ranging effort on classification anthropogenic soils in general has been underway for some years in the USA by the ICOMANTH committee of Soil Taxonomy [9]. Also important were the profound work of Nachtergaele at the 2 nd International Conference on Soil Classification [14] in which he re-examines what we should classify in soil classification, and the extensive efforts of Lehmann [11] to define key concepts for technic soils, and a presentation of the author at EUROSOIL 2004 [16]. Comments on the previous document ( Proposal: Classification of urban and industrial soils in the WRB of 29-November-2004) were received from Nachtergaele, Ditzler, Ahrens, Galbraith, Lehmann, and Arnold; these are taken into account here. The major criticisms were: Use of subjective descriptions rather than quantitative criteria, especially dominated ; The use of human transport as a diagnostic criterion; it was felt that this requires knowledge that can not be inferred from examination of the soil itself. The major change from the earlier document are (1) an increased objectivity of definitions;... 1 This group name is misleading in that it implies that the group contains human-influenced soils of all types, including the Technosols here defined. Lehmann proposes that the Anthrosols be renamed Agrosols, but this is also misleading, implying that all agricultural soils are included. Something like Cultisols might be better. 3

4 2 What is the soil we classify in the WRB? Traditional definitions of soil are not always applicable to what we would like to consider soils in urban and industrial environments. This section reviews previous definitions and then proposes an operational definition of soil for the WRB which is necessary for the later definition of Technosols. The pedogenetic view of soil was succinctly expressed by van der Eyk et al. [26]: The most fundamental and, possibly, the only real difference between soil and other unconsolidated geological materials is that, in the case of soil, the materials have been organized by natural, non-depositional processes into horizons. These natural, non-depositional processes are also called pedogenesis. This view was taken over by the WRB 1998 [8]: The soil cover is a continuous natural body which has three spatial and one temporal dimension... It is formed by mineral and organic constituents and includes solid, liquid and gaseous phases. The constituents are organized in structures, specific for the pedological medium... [which] result from the history of the soil cover and from its actual dynamics and properties... This definition seems to exclude bodies with no organic matter or voids and bodies with no internal pedological organisation. This latter can not be strictly intended, otherwise many Regosols would be excluded 2. The word unconsolidated is not used in this definition, but is implicit in the requirement for three phases. It does not mention the land surface, so could apply to subaqueous soils. This definition does not clarify what is meant by a natural body. This is also true of the most recent edition of the Keys to Soil Taxonomy [20] and Soil Taxonomy [19], which define soil as: sand... a natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the following: horizons, or layers, that are 2 e.g. landslides, fresh floodplain deposits, or recent windblown distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment This seems to exclude raw materials from technic processes; indeed the phrase natural body would seem to exclude any man-affected soil, although that was certainly not the intention. The reference to the land surface seems to exclude sub-aqueous soils. So, what is intended by natural body? This goes back to the concepts of Dokuchaiev and Jenny, who conceived of the soil as an entity in its own right, the product of soil-forming processes over time. The dictionary definition of natural [24] includes phrases like caused by nature; not artificial and uncultivated, wild ; surely this is not adequate for soils, many, if not most, of which are at least in part humanaffected, as clearly shown by Dudal [6]. A simpler concept is used by plantetary scientists [e.g. 1] and civil engineers: soil is any unconsolidated material with a high specific surface area and (potentially) three phases (solid, liquid, gas). For example: The term soil, as used by the US Army, refers to the entire unconsolidated material that overlies and is distinguishable from bedrock. Soil is composed principally of the disintegrated and decomposed particles of rock. It also contains air and water as well as organic matter derived from the decomposition of plants and animals. Bedrock is considered to be the solid part of the earth s crust, consisting of massive formations broken only by occasional structural failures. [25, p. 4-1] This is probably closest to the popular idea of soil. Recently Nachtergaele [14] has reformulated the question what is soil? to the more practical what should soil scientists study?. He makes a strong case for converting soil science into epidermic material science, at least for soil classification and mapping. That is, our task is to give meaningful names to all bodies at the Earth s surface that form the interface between atmosphere, hydrosphere, lithosphere, biosphere and anthosphere. The only non-soil in this view is sediment under water of a defined depth, typically 2 m. In this way we can deal with all environmental issues in what he terms the surface buffer zone. Nachtergaele then divides the Earth s epidermis into four classes, two of he terms materials and the other 4

5 two soils in the traditional sense, all of which should be classified and mapped. Using civil engineering concepts, only the first would not be considered soil. Geomorphic materials Unalterted natural materials such as rock, ice and surface water. Plants may grow directly on rock (or on organic material trapped in crevices), and micro-soils form from decaying vegetative materials and trapped dust, so that truly unaltered material is not common; perhaps minimally altered is a better wording. This material includes open water between the atmosphere and underwater unconsolidated material or rock. Anthropomorphic materials Materials created or transformed by human activity and without significant alteration, either because time has been too short or because they are recalcitrant. Examples are mine spoils, building rubble, pavements, and sludges. These are the current Spolic Anthropic Regosols and are the central concept of the Technosols ( 4.6). Anthropedogenic soils Soils in the sense of WRB 2002 where at least the top 50cm is heavily influenced by human activity; these are the current (non-spolic) Anthrosols (if there is anthropeodgenesis 3 ) or Anthropic Regosols (otherwise). Pedogenic soils All other soils in the sense of the WRB. Definitions for WRB 2006 Soil: The unconsolidated material, or material consolidated by recent pedogenesis, that overlies and is distinguishable from almost continous hard rock, or which underlies nearly-continuous technic hard rock (pavement) or water within 2 m from the interface of the earth surface with the atmosphere. The mention of recent pedogenesis is to exclude consolidated horizons in exhumed paleosols, which are considered geological layers. The surface is the interface with the atmosphere. Thus soils on roofs are included. The lower limit is not defined so that the entire regolith becomes the object of study [3, 27]. 3 defined in WRB 2002 as long-continued cultivation We also propose a term for non-pedogenic consolidated material and open water that is near the surface and therefore needs to be represented on soil maps: Non-soil near-surface materials: All materials that do not meet the definition of soil but which occur within 2 m below the interface between the earth surface and atmosphere. 3 The Technosols concept These are soils whose properties and pedogenesis are dominated by their technic origin or other profound human influence such as transporation. This is thus the major difference in terms of genesis, geography, and use potential compared to the 30 existing groups which is required to propose a new WRB Reference Group: Genesis Made, placed or exposed by human activity; would not otherwise occur at the Earth s surface; pedogenesis in these soils is strongly affected by materials and their organisation; Geography Mostly in urban and industrial areas, in compact areas, although in a complex pattern associated with other groups. Use potential Strongly affected by the nature of the material or the human activity that placed it; more likely to be contaminated than soils from other groups. The Technosols group is intended [21] to include: Soils from technic materials whose properties are dominated by these, even if there is significant pedogenesis; Soils from transported natural materials whose properties are dominated by the action of transportation, mixing and dumping; Pavements underlain by unconsolidated materials; Soils with impermeable liners that prevent water and gas flux. The Technosols group is intended to exclude: Soils with significant pedogenesis formed in natural materials in situ or disturbed or transported by natural processes; 5

6 Raw soils formed in situ on natural materials including those disturbed or transported by natural processes; Soils formed on technic materials with pedogenesis sufficient to transform the technic material into a product that is indistinguishable from one produced from natural materials; Soils freshly-exposed by partial or complete excavation of pedogenetic horizons; Soils profoundly affected by human activity substantially in situ for agricultural purposes. The Technosols name The techno root has several derivations in English. The meaning here is double: 4 1. technic ( artificial ): something manufactured by humans, not found in nature. 2. technique, implying something built by humans, using some defined method such as transportation and earth moving; The Greek τ ɛχνικoς loses its ending, which is replaced with o when forming a compound, in this case with Latin sol. 4 Definitions We first present a series of definitions which allow us to discuss urban soils with more precision. We then define a new reference group, the Technosols, and discuss the concepts that lead to its technical definition. Finally, definitions of other groups must be modified. 4.1 Natural, artificial, technic The dictionary definitions of natural and artificial are somewhat circular: Natural: Existing in or caused by nature; not artificial. [24, Definition 1] Artificial: Produced by human art or effort rather than originating naturally. [24, Definition 1] 4 Another derivation not included here is technical, opposite of general or conceptual. Most of the densely habited Earth has been influenced by humans (cultivation, grazing, settlement... ); more sparesely inhabited and even uninhabited areas have been indirectly influenced by the results of human activity (e.g. dust storms caused by over-grazing). It seems futile to argue about what is really natural when most soils have at least some human influence [6, 7]. So for the purposes of the WRB we propose the following: Natural soil material: Unconsolidated material produced exclusively by natural processes. Natural soil: A soil where direct human influence is restricted to clearing or grazing, and with no added materials of any origin other than low doses of fertilizers. Natural cultivated soil: A soil where direct human influence is restricted to cultivation to a depth of 40 cm or less, and with no added materials other than those for agricultural purposes (e.g. fertilizers, lime, pesticides). Artificial soil: A soil whose present form is largely produced by human art or effort. [24, Definition 1] 4.2 Artifacts An artifact 5 is something in the soil recognizably made by humans. These are useful to identify colluviation, human occupation, and industrial processes, and are already mentioned (but not defined) in WRB 1998 in the context of anthropedogenic horizons and urbic soil material and qualifier. The suggested definition for WRB 2006 is: Artifact: Solid or liquid material created or modified by humans as part of an industrial or artisanal manufacturing process and indentifiable as such in the soil. This definition has several implications: Material : exclude spade marks, layering or mixing; these are not artifacts in themselves, but 5 Note that the spelling with e is Oxford, with i Webster; WRB generally follows European (UK) orthography, so we should use artefacts ; however, WRB 1998 uses artifacts, so we maintain that spelling. 6

7 rather evidence of human disturbance, in common with discoloured soil material in archaeological sites; Created or modified : Material can be completely artificial (e.g. plastics) and also a nonnatural composition of natural material (e.g. bitumen for asphalt); Liquid : include chemicals of industrial origin, including those transformed, but not chemically altered, for transport; Does not include mined material or transported soil; the change in properties is from the transportation (loosening, compaction, mixing of a single material) but not in the material itself (see 4.3 Human-transported material ); Does not include transported natural liquids in their original form; The human origin must be evident in the material itself, not from written records or inference; If it has been transformed so that its origin is no longer identifiable, it is no longer an artifact. Some examples of artifacts are: Synthetic solids (compounds not found in nature): slag, plastic; Synthetic liquids: creosote, refined hydrocarbons; Waste liquids: sludges (e.g. brewery, municipal); Natural materials recognizably reworked by humans, e.g. flint knives or arrowheads; Natural materials processed by humans into a form or composition not found in nature: pottery, bricks, concrete, asphalt, lead shot; Mixed materials such as building rubble; Industrial dusts (both natural and synthetic); Pavements and paving stones; Natural materials mimimally processed but mixed in a way not found in nature, such as organic garbage. 4.3 Human-transported material This is any material in the pedon to be classified brought from outside this pedon, often with machinery. This can be for agricultural purposes (e.g. largescale terracing, mine spoil revegetation), for human settlement, or simply to dispose of material that is unwanted in its original location (e.g. dredgings). The suggested definition for WRB 2006 is: Human-transported material (abbreviation HTM ): Any solid or liquid material moved into a pedon from a source area outside of its immediate vincinity by intentional human activity, usually with the aid of machinery, without substantial reworking or displacement by natural forces. This is a parent material for pedogenesis, by analogy to fluvial soil material and colluvium. This definition has several implications: The restriction to intentional excludes dusts from wind erosion or mass movement (e.g. slumps) caused by human activity. The intention must be inferred from the type of material and manner of deposition, not from historical records. Liquids can be of any viscosity and include slurries, liquid manures, hydrocarbons and other industrial chemicals transported by humans. If material originally transported by humans has been further moved by natural forces such as erosion (water or wind) or flooding, the human influence is reduced, and it is no longer HTM. It is a different substrate and could be referred to as e.g. colluvium from human-transported material ; Similarly, if the material is substantially reworked in situ (e.g. by frost) the human influence is reduced, and so it is no longer HTM. It could be referred to as e.g. cyroturbated soil material originally human-transported ; The requirement that materials be moved farther than from the immediate vincinity excludes materials from ditching, terracing etc. where the transported material is placed as close as possible to the source; the transportation is too local. HTM may be mixed with non-transported material, e.g. spoil that is partially plowed into underlying natural soil. Thus a soil layer may consist of part HTM and part non-transported (but reworked in situ) material. 7

8 HTM may have substantial pedogenesis and still be identified as such. HTM may be identified in several ways: 1. By evidence of deposition processes after transportation (e.g. voids, compaction, disorganised fragements of diagnostic horizons); 2. By artifacts (not always present), although isolated artifacts may be mixed into non-transported soil by plowing or bioturbation; 3. By absence of evidence of transportation by natural forces (e.g. layering from flooding) or reworking in situ (e.g. cryoturbation). 4. By absence of pedogenesis which masks evidence of deposition. In each case the classifier must state the specific evidence for HTM. Historical evidence, such as site plans, may be used as an indication of where to find HTM but is not diagnostic; this is the same as for fluvic soil material which must be identified only from morphology, not from records of flooding. Lehmann [12] has recently proposed an alloic qualifier (probably from the English allo- prefix, from the Gk. αλλóς, meaning other ) for soils in any group with a substantial amount of human-transported natural soil material; it seems desireable to (also?) have this material clearly defined, as in the present proposal. 4.4 Technic soil material This is un- or weakly-consolidated material created by humans, having properties unlike natural materials. Property differences can be in composition, coherence, reaction, and form, among others. The difference must be documented in each case; no comprehensive list can be given. The suggested definition for WRB 2006 is: Technic soil material: (from Gr. θɛχνικóς skilfully made or constructed [15, technic Def. 2]) Un- or weaklyconsolidated material dominated by artifacts, with properties substantially different from those of natural materials. Such material is always human-transported to its first location, but it may be moved by water (scouring and subsequent sedimentation), wind (especially technic dusts) or ice. It need not be where it was originally deposited by humans, as long as it can be identified. Thus HTM and technic materials are intersecting sets; neither is a subset of the other. The first part of the definition (dominance of artifacts) will usually be obvious in the field from the nature of the material and its arrangement. This may be supported by historical documents such as maps of settlements and industrial works, and records of industrial processes. The second part of the definition (property differences) will require careful documentation. An example is the work of Zikeli et al. [29] and Zevenbergen et al. [28], who show that many properties of soils with vitric and andic properties derived from lignite and fly ashes are strongly influenced by the composition of the parent material and can be clearly distinguished from natural Andosols. Technic soil material can have substantial pedogensis, so long as soil properties are distinguishable from those which could have developed from natural materials. Examples of such properties are elevated levels of heavy metals or radioactivity. 4.5 Technic hard rock This is consolidated material created by humans, having properties unlike natural materials. The major property differences with natural hard rock is the chemical and physical composition. The suggested definition for WRB 2006 is: Technic hard rock: (from Gr. θɛχνικóς skilfully made or constructed [15, technic Def. 2]) Consolidated material resulting from an industrial process, with properties substantially different from those of natural materials. 4.6 The Technosols Reference Group Definition of Technosols (TE) in the key: Other soils having: At the third position 1. 50% (by volume) or more humantransported or 20% (by volume) or more technic soil materials or both, in any single layer or combination totalling: (a) either 50 cm within 100 cm from the soil surface; or 8

9 (b) at least half of the depth to a lithic or paralithic contact shallower than 100 cm from the soil surface; or 2. a continuous (almost) impermeable constructed liner of any thickness within 100 cm from the soil surface; or 3. technic hard rock (pavement) within 5 cm of the surface and covering at least 95% of the horizontal extent of the pedon, underlain at some depth shallower than 200 cm by unconsolidated material. TECHNOSOLS (TE) This definition requires the classifier to first identify layers, then determine the volume composition of each layer, and then sum the layer thicknesses of layers that meet the volume requirements. The thickness requirement may not be averaged; that is, the required volume of material must be present in each part of the layer or set of layers. For example, a 10 cm layer of pure technic material placed on the surface of a natural soil does not qualify it as a Technosol, even though the total volume of the technic material, averaged over 50 cm, is indeed 20%. Qualifiers for other groups are proposed for these situations ( 4.9). In soils where technic material is interbedded with other HTM, classification as a Technosol can result from a total thickness of HTM, both technic and not, adding the individual layers, of 50 cm. For example, on revegetated mine spoils, both the spoil and cover are considered HTM, so a 30 cm layer of transported topsoil on 20 cm or more of spoil would meet the definition. The volume proportions are set at the point that the technic or human-transported material will dominate soil behaviour; these may be adjusted as enough actual soils are classified and their behaviour observed. We propose a fairly low limit for technic material (20% of a 50 cm thick layer) because of the strong property differences from natural materials, and a higher limit for non-technic transported material. This definition allows a cover of up to 50 cm of materials moved by natural processes, e.g. dusts, alluvium or colluvium, over the material that qualifies the soil as a Technosol. The explicit mention of soils with liners is intended for the case where liners are covered by insufficient HTM to meet the volume requirement. The explicit mention of pavements is new to WRB, and intended for the case where the pavement, either from human-transported natural stone or technic material such as concrete or asphalt, is too thin to meet the thickness requirementf of the first clause. 4.7 Placement in the key Technosols are to be placed third in the key, after Histosols (HS) and Anthrosols (AT). This avoids redefining other groups to exclude technic and humantransported material. Histosols By tradition and the proposed rationale to the WRB 2006 key [4], organic soils are separated from mineral soils at the first key position. However, organic soils from dredgings, fly ash etc. have markedly different properties than natural HS (including frequent contamination); their definition must be re-written to exclude these. So, the definition of Histosols (HS) should be modified to begin with the following clause: Soils not meeting the definition of Technosols; and... It is also possible to duplicate the entire Technosol definition at this point. Anthrosols Anthrosols (AT) and Technosols (TE) form the conceptual group of soils with strong human influence in WRB 2006 [4]. There is little conflict between AT at the second position and TE; but in case the required horizons for AT have been developed on technic material this should have priority (so these soils are TE), but if developed in non-technic HTM (e.g. clean fill) they are AT. An example is a Hortic Anthrosols developed on clean fill used for urban gardens. So, the definition of Anthrosols (AT) should begin: Other soils having less than 20% (by volume) technic soil material in any single layer or combination totalling 50 cm within 100 cm from the soil surface and either... Note the clause about lithic contacts is not needed for Anthrosols, because such shallow soils could not meet any of the diagnostic horizons required for placement in this group. 9

10 4.8 Qualifiers for Technosols We discuss the qualifiers according to the proposal of Deckers et al. [4, 3.3]: 1. Prefix: Strongly expressed characteristics and intergrades, possibly closed by a haplic qualifier; 2. Suffix: Weakly expressed characteristics and extragrades; 3. Phases: Soil surface characteristics or special soil horizons uncommon in that group, often not found in large contiguous areas Prefix qualifiers (1): placement in Technosols These are intended to indicate the main reason the soil was placed in the Technosols, as well as any intergrades. In other reference groups, the priority order is intensity of soil genesis; the corresponding order here is degree of difference from natural soils, followed by the intergrades. First, four prefix qualifiers indicate how the soil qualifies as a Technosol, i.e. which clause of the key it matches; this also serves as first subdivision of the Technosols: Ekranic (from Russian ekran screen, from Fr. écran screen ) 6 Lined having technic hard rock within 5 cm of the surface and covering at least 95% of the horizontal extent of the pedon, underlain at some depth shallower than 200 cm by unconsolidated material (in Technosols only) ; having a continuous (almost) impermeable constructed liner within the first 100 cm but not within 5 cm of the surface (in Technosols only) ; Technic meeting the requirement for technic soil material for placement in the Technosols (in Technosols only) ; Spolic meeting the requirement for human-transported soil material for placement in the Technosols (in Technosols only). 6 This name comes from Stroganova & Prokofieva [22], who coined the name Ekranozems (Russian ekran and zemlya = soil ) for these soils; this term has been widely used informally at the past two SUITMA meetings. Ekranic Technosols are thus allowed to have a thin covering of unconsolidated materials and also cracks in a mostly solid pavement, e.g. between paving stones. Lined Technosols are those with a deeper impermeable layer. The technic qualifier is used to clearly indicate those soils dominated by technic material. If it were not used, a haplic qualifier could be used to close the list; but this would come after all the intergrades (next section), and there would then be no way to distinguish integrades from technic materials to those from nontechnic HTM. These can be combined according to the usual rules in WRB. For example, a pavement underlain by sufficient unconsolidated technic material would be a Techni-ekranic Technosol; if underlain by non-technic spoil a Spoli-ekranic Technosol; and if underlain by natural soil simply an Ekranic Technosol Prefix qualifiers (2): integrades Then, integrades to other reference groups, in key order. Histic (Histosols) having organic soil material cumulatively either 40 cm or more thick if the bulk density is 0.1 kg dm -3 or more or 60 cm otherwise, and starting within 40 cm from the soil surface (in Technosols only) ; These may be Histi-technic or Histispolic. Anthric (Anthrosols) As currently defined; because of the proposed construction of the keys these would all be Anthri-technic Technosols (since soils with anthropedogenic horizons in spoil would key out as Spolic Anthrosols. Hyperskeletic (Hyperskeletic Leptosols) having more than 90% (by volume) gravel or other coarse fragments to a depth of 100 cm from the soil surface. Note the use of volume proportion to accommodate railroad ballasts and other tipped crushed rock. Lithic (Leptosols other than Hyperskeletic) as currently defined; 10

11 Cryic (Cryosols) as currently defined; Hortic (Hortic Anthrosols) as currently defined; Terric (Terric Anthrosols) as currently defined; Fluvic (Fluvisols) as currently defined; these are primarily water-transported technic materials; Gleyic (Gleysols) as currently defined; Vitric (Vitric Andosols) as currently defined; Andic (Andosols other than Vitric) as currently defined; Hyperarenic (Arenosols) having a texture of loamy fine sand or coarser throughout the upper 100 cm of the soil. This is used in preference to the already-defined arenic, which is a suffix qualifier with less stringent requirements. These will always be combined with one of the prefixes from the first group, with the first qualifier closest to the group name. For example, Fluvi-Technic for Technosols from technic material deposited by flowing water. These definitions imply certain changes to existing definitions; see Suffix qualifiers These are for weakly-expressed characteristics and extragrades, presented here in proposed priority order. The qualifiers for named diagnostic horizons are for the situations where such horizons have developed in material that is still recognizably human-transported, technic, lined or pavements. This list can be expanded (or contracted) based on actual soil descriptions; the list here is not necessarily complete or correct. These are not considered intergrades (prefix qualifiers) but rather secondary characteristics (suffix qualifiers). Garbic primarily composed of mixed household wastes (in Technosols only) ; Note this is quite different from the WRB 1998 qualifier of the same name which is defined based on proportion of organic garbage; if the waste is primarily organic the histic qualifier may also be used, e.g. Histi-Spolic Technosols (garbic). Reductic having anaerobic conditions caused by soil gases (e.g. methane, CO 2 ) (in Technosols only) ; Skeletic as currently defined; Arenic as currently defined; Voidic having > 10% by volume coarse ( > 5 mm) voids in all material that qualifies as hyperskeletic. (in Hyperskeletic Leptosols and Technosols only) ; Dialemmic having a regular pattern of fine material between paving stones (in Ekranic Technosols only) ; These are soils where flow is concentrated at the surface into the cracks between paving stones, leading to a horizontally-differentiated pattern of fluxes below the ekranic surface; Mollic as currently defined; Umbric as currently defined; Calcic as currently defined; Calcaric as currently defined Phase qualifiers By tradition, phases are used to name map units, not pedons, but this is a fuzzy distinction, since map units are made up of pedons. [P]hases are used to subdivide taxa according to the practical needs for the purposes of a particular survey or interpretation.... [P]hases are not a part of the taxonomy. Their nature is determined by the foreseeable uses of the soils in a particular survey area... phases represent a number of classifications superimposed on the taxonomic classification to give part of the flexibility that is needed for the wide variety of uses made of soil. [19, pp ] 11

12 The classic case is eroded phases, where the erosion results in thinner surface horizons but not enough to change the taxonomic class. The entire map unit may be eroded, but often the various pedons in the unit show different degrees of erosion. So an individual pedon could be named as eroded or not. In WRB 1998 [8] phases were suggested for special soil horizons or layers (e.g.ṫhe proposed tosca phase of Luvic Phaeozems), as well as thin horizons or layers that do not affect the taxonomic name but do affect interpretations, such as thin surface mantles of fluvic materials. The role of phases is expanded in the proposed reform of the qualifiers for WRB 2006 [4, 3.3], where they are used instead of qualifiers for surface characteristics (e.g. gilgai, hummocks, terracing, inundation). For urban soils it seems appropriate to use these for remarkable features that affect soil use but which are not associated with any specific layer or internal pedogenic process. We propose phases for compaction and contamination. Note these are not part of WRB as such; they are mentioned here to guide mappers. Compacted soils Soils can become severely compacted by non-internal pedogenic processes to the point where soil function is greatly affected. This can be by human intervention (e.g. tillage or traffic) whether the compaction is intentional or not, or by animals (domestic or wild, e.g. by water holes or restricted grazing areas). We propose a phase that can be used in all reference groups where it is documented: Compacted severely and nontemporarily compacted so that soil function is substantially changed (further as epi-, endo-). The determination of severely, non-temporarily, and substantial change must be made and documented by the classifer. Examples are greatly-reduced infiltration or a root-limiting layer such as a plow pan. These are always evaluated by comparison to nonaffected soils; the classifier must present evidence that the compacted soil was previously like the uncompacted soil with which it is being compared. Nontemporary compaction is one that will not be alleviated within a few years without human intervention, e.g. by freeze-thaw or animal activity. (Note: the WRB already has a densic modifier, but it is used only for cemented spodic horizons ( ortstein ), so this name is not available.) Contaminated soils WRB 1998 has a toxic qualifier, used only in the Histosols and Gleysols: Toxic: having, within 50 cm from the soil surface, ions other than aluminium, iron, sodium, calcium or magnesium, in concentrations toxic to plants Three aspects of this definition make it unsuitable for urban soils: (1) the exclusive use of ions as indicators, not considering organic compounds and metals, (2) the exclusive use of plants as test organisms, not considering animals (including humans) or soil fauna, (3) the restriction to two reference groups. Contamination of urban soils by metals [e.g. 13] and organics [e.g. 10] is widespread. It may affect human health by direct contact (fumes, dust, aerosols) or by high concentrations in plants eaten from gardens. Urban and industrial contamination can also affect soil ecology, especially the population of mesofauna. Finally, grazing animals may be affected by contaminants or mineral imbalences (e.g. excess or deficient Se [23]). To better distinguish these, we propose removing the current toxic qualifier and replacing it with four phase names: Herbotoxic having a sufficiently high or low concentration of ions other than those of Al, Fe, Na, Ca or Mg, to markedly affect plant growth. The ions of the named elements are dealt with either at the reference group or qualifier level, because they are so associated with pedogenetic processes. Note that both high and low concentrations can be toxic, the latter because of imbalances or absolute deficiencies. Anthrotoxic having sufficiently high and persistent concentrations of metals or organic compounds to markedly affect the health of humans who come in regular contact with the soil. Ecotoxic Zootoxic having sufficiently high and persistent concentrations of metals or organic compounds to markedly affect soil ecology, in particular the population of mesofauna. having sufficiently high and persistent concentrations of metals or 12

13 organic compounds to markedly affect the health of animals, including humans, who ingest plants grown on these soils. These phase names can be used in any reference group where they are documented. The contaminant can be specified more precisely in local classifications or map unit names. 4.9 The Technic and Spolic qualifiers for other reference groups A soil with either technic or human-transported material may not key out as a Technosol because its content of both materials is too low, or too deep in the profile, to meet the requirements. An example is a thin layer of technic material over a natural soil. This can occur in any reference group. We propose three qualifiers, in priority order, which can be used in any reference group other than Technosols: Technic containing more than 5% (by volume) technic soil materials in any layer or combination totalling 20 cm within the first 100 cm, or at least 20% of the depth to a lithic or paralithic contact if shallower or more than 80% technic soil materials in any layer at least 5 cm thick within the first 100 cm (not in Technosols. As with the definition of the Technosols, the thickness requirement may not be averaged; that is, the required 5% by volume of technic material must be present in each part of the layer or set of layers. The second clause is intended for soils with thin almost-pure technic layers. Endotechnic containing more than 20% (by volume) technic soil materials in any single layer or combination totalling 50 cm thick within the first 200 cm but not within the first 100 cm or more than 80% technic soil materials in any layer at least 10 cm thick within the first 200 cm (not in Technosols This is the same amount of technic material required for a Technosol, Spolic only deeper. So smaller amounts of technic material below 100 cm would not be named in WRB If an almost-pure technic layer occurs below 100 cm we require it to be at least 10 cm thick, as opposed to only 5 cm if shallower. containing more than 20% (by volume) human-transported soil materials in any single layer or combination totalling 20 cm either within the first 100 cm or at least half of the depth to a lithic or paralithic contact if shallower (not in Technosols It is difficult to imagine human-transported material below a natural soil more than 1 m thick (perhaps in the case of flooding or colluviation over spoil), so until such is documented we do not proposed an endospolic qualifier by analogy to the endotechnic qualifier Changes to current definitions The definition of the Technosols and their qualifiers proposed above required modifications to other definitions in WRB Diagnostic horizons 1. The vitric qualifier for the Technosols only makes sense once the definition of vitric horizon is modified as follows: 10% or more volcanic glass, technic glass, and other primary minerals in the fine earth fraction Similarly for the andic horizon: The andic horizon... is a horizon resulting from moderate weathering of mainly pyroclastic deposits. However, they may also be found in association with non-volcanic materials (e.g. loess, argilites, technic ashes and ferralitic weathering products). 3. Similiarly for the terric horizon, which is expanded to include sludges that have similar properties to earthy manures, if they meet the other criteria of the terric horizon. A terric horizon (from L. terra, earth) develops through addition of 13

14 earthy manures, compost, organicrich sludge or mud over a long period of time. It can also develop by colluviation of such materials... With these changes, andic, vitric, and terric horizons can form in technic material, but they are then classified with the Technosols and named by the relevant prefix qualifier. Regosols (RG) Reference Group In the current keys, the four technic substrate qualifiers (garbic, reductic, urbic, and spolic), as well as the general anthropic qualifier, should be eliminated. All these soils are now in the Technosols. Obsolete definitions The following definitions are no longer needed and should be removed: Anthropogeomorphic soil material 14

15 References [1] Bullock, M. A.; Stoker, C. R.; McKay, C. P.; & Zent, A. P A coupled soil-atmosphere model of H 2 O 2 on Mars. Icarus 107(1): [2] Burghardt, W Diskussionspapier zum Workshop Klassifikation von Stadtböden vom In Arbeitskreis Stadtböden und Arbeitskreis Bodensystematik: Workshop Klassifikation von Stadtböden, 09-Juni Essen (D): (unpublished) [3] Cremeens, D. L.; Brown, R. B.; & Huddleston, J. H. (eds.) Whole regolith pedology. SSSA Special Publication 34. Madison, WI: Soil Science Society of America [4] Deckers, J.; Spaargaren, O.; Nachtergaele, F.; Berding, F.; Ahrens, R.; Micheli, E.; & Schad, P. 2004? Towards a rationale for the key and the qualifiers of WRB Eurasian Soil Science in preparation [5] Deckers, J. A.; Nachtergaele, F. O.; & Spaargaren, O. C. (eds.) World Reference Base for soil resources : Introduction. Leuven: ACCO [6] Dudal, R The sixth factor of soil formation. In Krasnilikov, P. V. (ed.), Soil Classification Petrozavodsk, Russia [7] Dudal, R.; Nachtergaele, F.; & Purnell, M. F The human factor of soil formation. In 17th World Congress of Soil Science, pp. CD ROM, paper 93. Bangkok: International Union of Soil Sciences [8] FAO World Reference Base for Soil Resources. World Soil Resources Report 84. Rome: Food and Agriculture Organization of the United Nations [9] Galbraith, J. M International Committee for the Classification of Anthropogenic Soils (ICO- MANTH) Circular Letter no. 5. Circular letter, USDA-NRCS [10] Krauss, M. & Wilcke, W Polychlorinated naphthalenes in urban soils: analysis, concentrations, and relation to other persistent organic pollutants. Environmental Pollution 122(1):75 89 [11] Lehmann, A Proposals for the consideration of urban soils within the WRB (World Reference Base for Soil Resources). In Krasnilikov, P. V. (ed.), Soil Classification Petrozavodsk, Russia [12] Lehmann, A Refined proposal how to respect anthropogenic soils within the WRB. Working letter [13] Lu, Y.; Gong, Z.; Zhang, G.; & Burghardt, W Concentrations and chemical speciations of Cu, Zn, Pb and Cr of urban soils in Nanjing, China. Geoderma 115(1-2): [14] Nachtergaele, F The soils to be classified in the World Reference Base for Soil Resources. In Krasnilikov, P. V. (ed.), Soil Classification Petrozavodsk, Russia [15] Oxford University Press Oxford English Dictionary. On-line document. oed.com/ [16] Rossiter, D. G Classification of urban and industrial soils in the world reference base for soil resources. In EUROSOIL 2004: 2nd European Soil Science Conference September 2004, Freiburg im Bresgau (D) [17] Rossiter, D. G. & Burghardt, W Classification of urban and industrial soils in the World Reference Base for Soil Resources. In Morel, J.-L. (ed.), SUITMA Nancy (F). Conference CD-ROM: 1028.pdf [18] Sobocka, J Urban soils vs anthropogenic soils, their differentiation and classification. In Morel, J.-L. (ed.), SUITMA Nancy (F). Conference CD-ROM: 1079.pdf 15

16 [19] Soil Survey Staff Soil Taxonomy: a basic system of soil classification for making and interpreting soil surveys. Agricultural Handbook 436. Washington, DC: US Department of Agriculture Soil Conservation Service, 2nd edition [20] Soil Survey Staff Keys to Soil Taxonomy. Washington, DC: US Government Printing Office, 9th edition [21] Spaargaren, O Report on the trans-ural polar tour and the International Conference on Soil Classification WRB Newsletter 5:4 9 [22] Stroganova, M. & Prokofieva, T Urban soils classification for Russian cities of the taiga zone. In Micheli, E.; Nachtergaele, F. O.; Jones, R. J. A.; & Montanarella, L. (eds.), Soil Classification 2001 (European Soil Bureau Research Report No. 7, EUR EN), pp Luxembourg: Office for Official Publications of the European Community [23] Tan, J.; Zhu, W.; Wang, W.; Li, R.; Hou, S.; Wang, D.; & Yang, L Selenium in soil and endemic diseases in China. The Science of The Total Environment 284(1-3): [24] Thompson, D. (ed.) The concise Oxford dictionary of current English. Oxford: Oxford University Press, 9th edition [25] United States Army Military soils engineering. Field Manual Fort Leonard Wood, MO: US Army Engineer School, Change 1, 4 June 1997 edition [26] van der Eyk, J. J.; MacVicar, C. N.; & de Villiers, J. M Soils of the Tugela Basin: a study in subtropical Africa. Natal Town & Regional Planning Reports 15. Natal (RSA): Natal Town & Regional Planning Comission. [27] Zanner, C. & Graham, R Deep regolith: exploring the lower reaches of soil. Geoderma 126(1-2):1 3 [28] Zevenbergen, C.; Bradley, J. P.; Van Reeuwijk, L. P.; Shyam, A. K.; Hjelmar, O.; & Comans, R. N. J Clay formation and metal fixation during weathering of coal fly ash. Environmental Science & Technology 33(19): [29] Zikeli, S.; Kastler, M.; & Jahn, R Classification of anthrosols with vitric/andic properties derived from lignite ash. Geoderma 124: