Trace and major element contents, microbial communities, and enzymatic activities of urban soils of Marrakech city along an anthropization gradient
Due to their close proximity with the population, urban soils are extensively affected by human activities that release considerable technogenic inputs resulting in an overall soil degradation and leading to an increase of water-extractable fraction of trace elements. This work aimed to determine the influence of anthropization on trace and major element concentrations and to assess how it might also affect soil biochemical and microbiological parameters in an urban area of Marrakech city, Morocco.
Materials and methods
The work was carried out on nine topsoils located along an anthropogenic gradient from a suburban area to the city center. The percentage of technogenic fraction (TGF) (e.g., building material, plastic, wood, metallic material, bones, glass, paper, fabric) was used to quantify the degree of human interference in the different soils. Physicochemical parameters were measured: pH (in water solution), TOC (Anne method), TKN, and Olsen phosphorus. The total fraction of trace and major elements (ISO NF 11446) and their water-soluble fraction were analyzed with an ICP-OES. Enumeration of cultivable microorganisms (bacteria, fungi, actinomycetes) was conducted on culture media. Dehydrogenase, alkaline phosphatase, and urease activities were colorimetrically measured, and the structure and diversity of soil bacterial communities were determined by denaturing gradient gel electrophoresis (DGGE) technique.
Results and discussion
In general, trace and major element concentrations showed increasing levels along the anthropogenic gradient, except for Ca, Mg, B, and Cd. However, trace element concentrations remained below the standard international limits for soils. Total numbers of microorganisms (bacteria, fungi, and actinomycetes) varied significantly among sites, with bacterial counts directly related to the anthropogenic gradient, significantly increasing from suburban area to the city center. Dehydrogenase activity decreased throughout the anthropogenic gradient, while phosphatase and urease activities varied between sites independently of the gradient. DGGE profiles showed that bacterial diversity was higher in the most anthropized soils, where their community structure seemed to be influenced by the total concentrations of Zn, As, Cr, Cu, Ni, Pb, and the technogenic fraction.
Overall, trace and major element concentrations and the technogenic fraction were higher with increasing levels of urbanization. Microbiological and biochemical parameters appeared significantly influenced by the anthropogenic inputs without being systematically inhibited along the anthropogenic gradient. Dehydrogenase activity decreased along the anthropization gradient, and thus may be used as a proxy to assess the effect of anthropization on soil biological functions.
KeywordsEcosystem services SUITMA’s soils Metal contamination Soil enzymes Technogenic fraction Technogenic soils
The authors would like to thank the scientific collaboration of CBQF under the Fundação Ciência e Tecnologia (FCT) project [UID/Multi/50016/2013].
The study is financially supported by Centre National de Recherche Scientifique et Techniques [grant no. PPR 22/2015] and by the project PhytoSudoe (SOE1/P5/E0189) - Demostração de melhorias na biodiversidade do solo, funcionalidade e serviços ambientais de locais contaminados e/ou degradados sob intervenção de fito-tecnologias dentro da região Interreg Sudoe, funded by FEDER - Fundo Europeu de Desenvolvimento Regional under Programa INTERREG.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Alef K, Nannipieri P (1995) Methods in applied soil microbiology and biochemistry. Academic Press, LondonGoogle Scholar
- Anne P (1945) Sur le dosage rapide du carbone organique des sols. Ann. Agr 2: 161–172Google Scholar
- Boon N, De Windt W, Verstraete W, Top EM (2001) Evaluation of nested PCR-DGGE (denaturing gradient gel electrophoresis) with group-specific 16S rRNA primers for the analysis of bacterial communities from different wastewater treatment plants. FEMS Microbiol Ecol 39:101–112Google Scholar
- Calvarro LM, Santiago-Martin A, Gomez JQ, Gonzalez-Huecas C, Quintana JR, Vazquez A, Lafuente AL, Rodriguez-Fernandez TM, Vera RZ (2014) Biological activity in metal-contaminated calcareous agricultural soils: the role of the organic matter composition and the particle size distribution. Environ Sci Pollut Res 21(9):6176–6187CrossRefGoogle Scholar
- Ding Y, Liu Y, Liu S, Li Z, Tan X, Huang X, Zeng G, Zhou L, Zheng B (2016) Biochar to improve soil fertility. A review. Agron. Sustain. Dev. 36:36. https://doi.org/10.1007/s13593-016-0372-z
- El Faiz M (2002) Marrakech patrimoine en péril. Actes Sud / Edit, ArlesGoogle Scholar
- Gevorgyan GA, Ghazaryan KA, Movsesyan HS, Zhamharyan HG (2017) Human health risk assessment of heavy metal pollution in soils around Kapan mining area, Armenia. Electron J Nat Sci 2:29–33Google Scholar
- Hafeez F, Spor A, Breuil MC, Schwartz C, Martin-Laurent F, Philippot L (2012) Distribution of bacteria and nitrogen-cycling microbial communities along constructed technosol depth-profiles. J Hazard Mater 15:231–232 88–97Google Scholar
- Haut-commissariat au plan (2014) Ressensement général de la population et de l’habitat-2014. http://www.hcp.ma/. Accessed 30 March 2017
- Hu B, Jia X, Hu J, Xu D, Xia F, Li Y (2017) Assessment of heavy metal pollution and health risks in the soil-plant-human system in the Yangtze River Delta, China. Int J Environ Res Public Health 14:1–18Google Scholar
- Ita RE, Anwana ED (2017) Geochemical assessment of heavy metal contamination in rural and urban wetlands in Akwa Ibom State, Nigeria. NY Sci J 10(11):43–51 ISSN 1554–0200 (print); ISSN 2375-723X (online)Google Scholar
- IUSS Working Group WRB (2015) World Reference Base for Soil Resources 2014, Update 2015. International soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports No. 106. FAO, RomeGoogle Scholar
- Kabata-Pendias A (2011) Trace elements in soils and plants. CRC Press, FloridaGoogle Scholar
- Lane DJ (1991) 16S/23S sequencing. In: Stackebrandt E, Goodfellow M (eds) Nucleic acid techniques in bacterial systematics. Wiley, Chichester, pp 171–204Google Scholar
- Levin MJ, Kim KHJ, Morel JL, Burghardt W, Charzynski P, Shaw RK, IUSS Working Group SUITMA (2017) Soils within Cities. Schweizerbart Science Publishers, StuttgartGoogle Scholar
- Minnikova T, Denisova T, Mandzhieva S, Kolesnikov S, Minkina T, Chaplygin V, Burachevskaya MV, Sushkova SN, Bauer TV (2017) Assessing the effect of heavy metals from the Novocherkassk power station emissions on the biological activity of soils in the adjacent areas. J Geochem Explor 174:70–78CrossRefGoogle Scholar
- Muller G (1969) Index of geoaccumulation in sediments of the Rhine River. J Geol 2:109–118Google Scholar
- Muyzer G, De Waal EC, Uiterlinden AG (1993) Profiling of complex microbial populations by denaturating gradient gel electrophoresis analysis of polymerase chain reaction amplified genes coding for 16S rRNA. Appl Environ Microbiol 59:695–700Google Scholar
- Pouyat RV, Szlavecz K, Yesilonis ID, Groffman PM, Schwarz K (2010) Chemical, physical, and biological characteristics of urban soils. In: Aitkenhead-Peterson J, Volder A (eds) Urban ecosystem ecology, agronomy monographs 55. Madison, pp 119–152Google Scholar
- Thalmann A (1968) Zur Methodik der Bestimmung der Dehydrogenaseaktivitat im Boden mittels Triphenyltetrazoliumchlorid (TTC). In: Alef K, Nannipieri P (eds) Methods in Applied Soil Microbiology and Biochemistry. Academic Press, London, pp 228–230Google Scholar
- United Nations (2014) Department of Economic and Social Affairs, Population Division. World Urbanization Prospects: The 2014 Revision, Highlights (ST/ESA/SER.A/352)Google Scholar
- Utobo EB, Tewari L (2015) Soil enzymes as bioindicators of soil ecosystem status. Appl Ecol Environ Res 13(1):147–169Google Scholar
- Wilbaux Q (2001) La médina de Marrakech Formation des espaces urbains d'une ancienne capitale de Maroc. L'Harmattan, ParisGoogle Scholar
- Wolińska A, Stępniewska Z (2012) Dehydrogenase activity in the soil environment, dehydrogenases, Canuto RA (ed). InTech. https://doi.org/10.5772/48294