Classification of soils in urban agglomerations

CATENA

vol. 16, p. 269-275

Cremlingen 1989 ]

C L A S S I F I C A T I O N O F SOILS IN URBAN AGGLOMERATIONS H.-P. Biume, Kiel Summary

den der/aus Auftr~ige(n) auf. Ein Auftrag wird als anthropogene Pedogenese Sealed surfaces, modified soils with nat- angesehen, woraus die Klassifikation als ural development and soils of, or on Auftragsboden oder Urbic Anthrosol anthropogenic deposits are encountered folgt, teils als anthropogene Lithogenese, in urban agglomerations. Some authors woraus dann keine klassifikatorische consider the deposition of soil material Sonderstellung folgt. Aus pedogenetisin urban environments as anthropogenic chen und ~Skologischen Griinden ist letzpedogenesis, and hence classify soils on teres vorzuziehen. Die Einheit "Urthis materials as "Auftragsb6den" (De- bic Anthrosol" der revidierten Legende posit soils) or Urbic Anthrosols. If, how- der Weltbodenkarte sollte daher verworever, this deposition of soil material is fen werden. B~Sden aus/neben Miillconsidered to be anthropogenic lithogen- oder Kl~irschlammdeponien sowie iiber esis, no new soil classification unit is nec- schadhaften Erdgasleitungen enthalten essary, and the unit "Urbic Anthrosol" Methan in der Bodenluft, sind redoxiof the revised legend of the world soil morph ver~indert und sollten daher in der map can be dropped. This is preferable Klassifikation eine eigene Einheit bilden. for ecological and pedogenetic reasons. But soils on or near landfills and sewage sludge and over gaspipe leaks contain 1 Introduction methane in their atmosphere and their redox regime results in special morpho- Mapping soil distribution in urban aglogical features. They should be assigned glomerations yields three major cateto a special unit; the name Methanosol gories: is suggested. 1. Sealed surfaces

Zusammenfassung: Zur Kiassifikation der Biiden stiidtischer Verdichtungsr~ume In st~idtischen Verdichtungsr~iumen treten versiegelte BiSden, ver~inderte B/Sden natiirlicher Entwicklung und BoISSN 0341-8162 (~)1989 by CATENAVERLAG, D-3302 Cremlingen-Destedt,W. Germany 0341-8162/89/5011851/US$ 2.00 + 0.25

2. Modified soils with natural development and 3. Soils of/on deposits. This article discusses how such soils can be classified. According to the West German and international systems of soil classification, classification should,

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in principle, use criteria of pedogenesis (ARBEITSKREIS DBG 1985, FAOUNESCO 1988).

2

Soils of sealed surfaces

The soils of sealed surfaces have mostly been levelled and compacted. In the case of complete sealing, as under asphalt roads and buildings, the soils or soil remains are preserved as fossils; with less complete sealing, as under cobbles or slag, atmospheric influences continue to act, and the soils provide rooting space e.g. for roadside trees. Sealed soils should be mapped on large scale maps, and their percentage coverage should be noted on small scale maps. On the Map of Soil Associations of West Berlin (scale 1:50 000; GRENZIUS & BLUME 1985) and on the Soil Map of Kiel and Surroundings (scale 1:20 000; CORDSEN et al. 1988) the degree of surface sealing is shown in five classes: little (0-15% sealed), moderate (10-50%), medium (45-75%), strong (70-90%) and very strong (85-100%), the percentages having been determined from aerial photographs (according to BC)CKER 1985). Sealed surfaces may be covered by soil substrates secondarily, either from dust accumulation or deliberate application; natural or "garden" vegetation may be present, e.g. on flat roofs (DARIUS & DREPPER 1984).

3

Modified soils with natural development

In Central Europe, the category of modified soils with natural development has primarily included forest soils with a range of properties that vary according to age, parent material, topography, and CATEN~An

climate. Frequently, intermediate use as farmland has resulted in these soils being influenced by mixing, liming, fertilization, drainage, or irrigation. Specific urban modifications followed. They include (CRAUL 1985, GRENZIUS 1987): greater depth to groundwater (lowering of water table or elevation of surface by deposits or additions of substrate) disruption of the soil profile by mixing and levelling removal of topsoil addition of small amounts of material (easily mixed into existing topsoil) compaction by traffic or construction site preparation alkalization by sewage and waste contamination • fertilization in gardens • pollution from burning, traffic, industries. The soils modified in these ways in urban agglomerations have been studied and described by various authors. For instance, RUNGE (1975), BLUME (1982), and GRENZIUS (1987) described such soils in Berlin, BILLWITZ & BREUSTE (1980) in Halle, SCHRAPS (1987) in Bochum, and DUMANSKI et al. (1979) in Ottawa. The soil classification system used in the Federal Republic of Germany permits additions of natural or artificial substrates up to 40 cm thick to be tolerated, because these are generally mixed with the underlying material immediately or

Interdisciplinary Journal of SOIL S C I E N C E - - H Y D R O L O G Y - - G E O M O R P H O L O G Y

Soils in Urban Agglomerations

later. Often, a thin layer of topsoil removed at construction sites before excavation is applied to the soil surface; in other cases the levelling of uneven surfaces has resulted in the deposition of soil material removed from elsewhere. Similar soil redistribution occurs in agricultural practice. Soils modified in such ways can be classified within the systems for natural soils in the same way as farmland soils (FAO-UNESCO 1988). Eutrophic, calcareous and/or drained soils mostly occur (e.g. Eutric or Calcaric Cambisol, formerly Dystric Cambisol). In addition, the German classification distinguishes soils that are strongly influenced by man (AKB 1985):

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Soils containing methane but which otherwise have a natural development may, under certain circumstances, be present near landfills. If the landfill lies in a former gravelpit, conditions are favourable for landfill gas to spread far sideways and to induce reducing conditions in neighbouring soils. Typical phenomena are the black colour of the soil (caused by metal sulphides) and the morbidity of deep-rooted trees (BLUME et al. 1983, MOUIMOU 1983). Where sand is overlain by impermeable loam conditons are especially favourable for the lateral movement of methane (up to 50 m) (BLUME et al. 1979). Soils with reduced horizons but whose oxygen deficiency is not caused by excess water may, however, also be formed by natural • Hortisols with Ah>4 dm as a result processes under the influence of volcanof repeated incorporation of organic ism. KERPEN (1960) and PALMER & fertilizers and waste, reworking and CHILDS (1985) described soils in which geothermal CO2 and other gases had bioturbation during gardening displaced soil oxygen, causing reducing • Rigosols with Ah>3 dm caused by conditions: Iron was reduced and redisrepeated trenchploughing (e.g. of tributed, it accumulated as ferihydrite in park areas) the topsoil (especially along root channels) and in neighbouring soils. In the revised legend of the Soil Map of the World, Hortisols are called 4 Soils on/from deposits Fimie Anthrosols, and Rigosols Arie Anthroso|s. In both cases, however, the Soils on/from deposits have developed minimum thickness of altered topsoil is on at least 4 dm (AKB 1985) or 5 dm 50 cm (FAOfl3NESCO 1988). (FAO/UNESCO 1988) of deposited natThere is also a need to designate ural (mining waste, excavation material) soils that have been mixed deeply or technogenic (rubble, slag, domestic once, and soils that contain methane. waste) matter which is then altered in "Mixed soils" are found where pits have situ by soil-forming processes. These subbeen refilled with the original mate- strates vary markedly in their properties, rial. RUNGE (1975) classified them especially the technogenic ones (KINas Regosols. The soils of cemeteries, NER et al. 1986). Some authors condescribed as "Nekrosols" by BLUME sider the substrate deposition to be an (1982) and GRENZIUS (1987), are anthropogenic lithogenesis; others view deeply mixed and enriched with organic it as pedogenesis. This results in different matter to great depths. suggestions on how these soils should be CATENA--An Interdisciplinary Journal of SOIL S C 1 E N C E ~ Y D R O L O G Y ~ E O M O R P H O L O G Y

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classified. The proponents of anthropogenic pedogenesis suggest that these soils be classified as "AuftragsbiSden" (Deposit Soils) (AG BODENKUNDE 1982, ARBEITSKREIS DBG 1985). Deposols (SCHRODER, pers. comm.), or Urbic Anthrosols (FAO-UNESCO 1988) and be assigned to the Anthrosols. With subdivision according to the nature and origin of the parent material, as practised in the West German system, the frequent occurrence of mixed and interlayered natural and technogenic materials must be accounted for. Those authors who consider that substrate deposition is a process of anthropogenic pedogenesis often point at parallels in the genesis of Fluvisols or Fimic Anthrosols. The development of these soils however, is characterized by the repeated addition of small amounts of material which is subsequently incorporated into the underlying material. The topsoil of Fimic Anthrosols consists of a mixture of the underlying and added substrate (effected by ploughing). In cities, however, large amounts of material are usually deposited at one time (landfills) and are generally not mixed intimately with the underlying material. Soils of this type sometimes contain contaminants. This problem is not specific for urban areas: cropland may also contain toxic levels of heavy metals after the frequent application of sewage sludge; so may natural soils on ultrabasic rock. If, on the other hand, the deposition of substrate is considered to be an anthropogenie lithogenesis, the soils may be classified according to their development and resulting horizonation, just as soils on natural substrates are classified. The main soil-forming processes are humus accumulation, structure formation,

gleying, dacalcification, and acidification. The following soils have frequently been encountered in urban agglomerations (GRENZIUS 1987, CORDSEN et al. 1988, soil units of the West German system) : a) Lockersyrosem with Ai-C, b) Regosol with Ah-C (<2% CaCO3), c) Pararendzina with Ah-C CaCO3),

(>2%

d) Gley with Ah-Gr, (all on redeposited natural or technogenic parent material). According to FAO-UNESCO (1988): a) Eutric Regosol or Eutric Leptosol (if developed on rubble over thin concrete slabs) with ochric A, b) Umbric Regosol, c) Calcaric Regosol, d) Eutric or Umbric Gleysol with Ah(Cg)-Cr. On deposits in Berlin, Cg and Cr horizons were observed to develop within years, resulting in Gleysols, and Ah horizons developed within decades, resulting in Regosols. A classification according to genetic principles is also sensible ecologically. For example, Calcaric Regosols that have developed on rubble resemble analogue soils on natural parent material in their species diversity and abundance of associated plants and soil organisms, but differ strongly from fresh rubble deposits (WEIGMANN et al. 1981). In Gleysols on artificial substrates oxygen deficiency is much the same as on natural Gleysols.

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The Arbeitskreis Bodensystematik of the D B G suggests a classification according to the existing system including the statement of the parent material ("soil form"). Soils developed on anthropogenic substrates could be characterized by the prefix "Depo-" (e.g. DepoPararendzina) in the West German soil classification system. Soils in which pedogenesis proceeds in an atypical direction because of the nature of the parent material are special cases. Examples include soils on sewage sludge and domestic waste. These substrates contain a large amount of protein-rich easily degradable organic matter. Microbial activity continues over long periods (40-80 years) and, with compaction and subsequent oxygen deficiency, anaerobic breakdown causes the build-up o f methane and other landfill gases. Soils on such material contain at least 5% of methane in their atmosphere and they are black from metal sulphides. Their topsoil is rich in humified matter, and root channels and aggregate surfaces are coloured by oxidized iron compounds (Agh). SIEM et al. (1987) suggest calling such soils "Methanosols'. So far, the following subunits have been observed: • Ochric Methanosol with ochric A above a reduced methanous C (Cr) • Umbric Methanosol with umbric A above an oxidized Cg and a Cr • Gleyic Methanosol with ochric A and a reduced C with groundwater influence • Stagnic Methanosol with ochric A and a mottled B by stagnating surface water above a methanous reduced C. CATENA--An Interdisciplinary Journal of SOIL SCIENCE

Soils on sulphide-rich mining wastes (Ruhr District, K E R T H 1988) have a similar morphological appearence, AohC horizonation from groundwater influence, and additional strong acidification (which should also be considered in their classification). Similar soils are, however, also found in nature: groundwater-influenced Thionic Fluvisols from sulfide-rich mud, often with free methane, are similar both morphologically and genetically, and can be very acid (Dystric Thionic Gleysols). Natural soils with reduction in the absence of groundwater also occur near volcanic fumaroles where CO2 and CH4 gases permeate the soil ( B L U M E 1988).

5

Conclusions

The soils of urban agglomerations should be classified similarly to those of the open landscape on the basis of their development and diagnostic properties, even if their parent material is of anthropogenic origin. The latter is the case if natural substrates are redeposited or if the substrate consists o f man-made material. The unit "Urbic Anthrosols" of the FAO-UNESCO legend should be dropped. It would make sense to denote the human influence on lithogenesis by the prefix "Depo'. A calcareous Gleysol with umbric epipedon and redoximorphous appearance due to a high water table formed on rubble containing bricks would then be called an Umbric Depo-Calearic Gleysol. On the other hand the two units Fimic and Aric Anthrosol should be retained, since here man has exerted influence on pedogenesis itself by repeated addition of organic matter and turbation. Soils with oxygen deficiency not caused by excess water, but in which the

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l i b e r a t i o n o f m e t h a n e a n d other gases has caused reduced c o n d i t i o n s should form a distinct class, with the suggested n a m e "Methanosol". They could be subdivided into Ochric, U m b r i c , Gleyic, a n d Stagnic M t h a n o s o l s . I f only the subsoil (deeper t h a n 50 cm) is influenced by m e t h a n e , as is the case in m a n y soils of otherwise n a t u r a l d e v e l o p m e n t in the vicinity o f landfills, this should be n o t e d in the s u b u n i t only. A M e t h a n o d y s t r i c C a m b i s o l w o u l d t h e n be a n acid C a m bisol c o n t a m i n a t e d by m e t h a n e in the way described above. Sealed soils should also be assigned to a p r o p e r unit. T h u s would enable the complete soil m a p p i n g of u r b a n areas.

BOCKER, R. (1985): Bodenversiegelung - Verlust vegetationsbedeckter Fl/ichen in Ballungsr~iumen.Landschaft und Stadt 17, 57-61. CORDSEN, E., SlEM, H.-K., BLUME, H.-P. & FINNERN, H. (1988): Bodenkarte 1:20 000 Stadt Kiel und Umgebung. Geolog. Landesamt Kiel.

References

GRENZIUS, R. (1987): Die BiSden Berlins (W), mit Karte. Diss. Techn. Univ. Berlin. GRENZIUS, R. & BLUME, H.-P. (1985): 01.01 BodengeseUschaften, 1:50 000; im Umweltatlas Berlin. Kulturbuchv. Berlin. KERPEN, W, (1960): Die B/~den des Versuchsgutes Rengen. Wissenschaftl. Berichte Landw. Fak. Bonn 5, Landwirtschaftsverlag Hiltrup.

AG BODENKUNDE DER GEOLOG. LAN-

DES.g,MTER (1982): Bodenkundl. Kartieranleitung. Schweizerbart, Stuttgart. ARBEITSKREIS BODENSYSTEMATIK DER D B G (1985): Systematik der B/Sden der BRD. Mitteilgn. Dtsch. Bodenkdl. Gesellsch. 44, 1-91. BILLWITZ, K. & BREUSTE, J. (1980): Anthropogene Bodenver/inderungenim Stadtgebiet von Halle/Saale. Wissenschaftl. Z. Univ. Halle 29, 25-43. BLUME, H.-P. (1982): B/Sden des Verdichtungsraumes Berlin. Mitteilgn. Deutsch. Bodenkdl. Ges. 33, 269-280. BLUME, H.-P, (1987): Bodenkartierung yon st/idtischen Verdichtungsr§umen. Die Heimat (Neumtinster) 94, 280-288. BLUME, H.-P. (1988): The fate of iron during soil formation in humid-temperate environments. In: I.W. Stucki et al. (eds.), Iron in soils and clay minerals. 749-777. D. Reidel Publ., Dordrecht. B L U M E , H.-P., HOFMANN, I., MOUIMOU, D. & ZINGK, M. (1983): Bodengesellschaftauf und neben einer Miilldeponie. Z. Pflanzenern. u. Bodenkde 146, 62-71. BLUME, H.-P., BORNKAMM, R. & SUKOPP, H. (1979): Vegetationssch~iden und Bodenver~inderungen in der Umgebung einer Miilldeponie. Z. f. Kulturtechn. und Flurberein. 20, 65-79.

CRAUL, P.J. (1985): A description of urban soils and their desired characteristics. J. Agriculture 11, 330-339. DARIUS, F. & DREPPER, $. (1984): RasenD/icher in Westberlin. Das Gartenamt 33, 309315. DUMANSKI, J., MARSCHALL, J.B. & HOFFMANN, E.C. (1979): Soil capability analysis for regional land use planing. A study of the Ottawa urban fringe, Canada. Can. J. Soil Sci. 59, 363-390. FAO-UNESCO (1988): Soil map of the world, revised legend; world soil, resources report 60. FAO-Rom.

KERTH, M. (1988): Die Oxidation des Pyrits - - dominierender chemischer Verwitterungsvorgang in Berghaldenrohb/Sdendes Ruhrgebietes. Mitteilgn. Dtsch. Bodenkdl. Gesellsch. 56, 375-380. KINNER, V., KOTI'ER, L & NICLAUSS, M. (1986): Branchentypische Inventarisierung von bodenkontaminationen. UBA-Texte 31/86, Umweltbundesamt Berlin. MOUIMOU, D. (1983): Genese, Dynamik udn Okologie der b/Sden auf und neben Miilldeponien. Diss. Inst. Ftir Okologie, Techn. Univ. Berlin. PALMER, R. & CHILDS, C. (1985):Iron oxide pans in Taranaki Soils. Soil Res, Report SR 7. New Zealand Soil Bureau, New Plymouth. RUNGE, M. (1975): Westberliner B/Sdenanthropogener Litho- oder Pedogenese. Diss. Inst. f'tir Okologie, Techn. Univ. Berlin. SCHRAPS, W.C. (1987): Bodenkartierung st/idtischer Freifl~ichen. Mitteilgn. Dtsch. Bodenkundl. Gesellsch. 53, 269-274.

CATENA An Interdisciplinary Journal of SOIL SCIENCE--HYDROLOOY--GEOMORPHOLOGY

Soils in Urban Agglomerations

SEEM, H.-K., CORDSEN, E., BLUME, H.-P. & FINNERN, H. (1987): Klassifizierung von BiSden anthropogener Lithogenese - - vorgestellt am Beispiel von B~Sdenim Stadtgebiet Kiel. Mitteilgn. Deutsch. Bodenkdl. Gesellsch. 55, 831836. WEIGMANN, G., BLUME, H.-P., MATTES, H. & SUKOPP, H. (1981): C)kologie im Hochschulunterricht. In: G. Trommer & W. Riedel (Ed.), Didaktik der ¢3kologie. Aulis, KSln.

Address of author: H.-P. Blume

Institut f'fir Pfianzenern/ihrung und Bodenkunde Olshausenstr. 40 D-2300 Kiel 1 BRD

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