Abstract
Urban soils are characterised by a strong anthropogenic influence. Potentially toxic elements were studied in various horizons of 35 urban soils in Havana, Cuba, classified as Urbic or Garbic Technosols. Pseudo-total, available, and acid-oxalate extractable concentrations were determined. The pseudo-total concentrations were generally higher than the average values for the world’s soils but similar to those published for urban soils. In a few cases, very high values of copper or lead were found. Nickel and chromium concentrations exceeded the maximum allowable concentrations for agricultural soils in 22% and 12% of samples. Vanadium concentrations were always very high. There was minimum enrichment of most samples in Co, Mn, As, Cd, Cr, Cu, and Ni, but outliers reached moderate or significant enrichment. Enrichment was significant for V, while for Pb, Zn, and Hg the median values denoted moderate enrichment, but outliers reached significant enrichment in Zn and extremely high enrichment in Pb and Hg. The available elements amounted to between 0.07% of the pseudo-total vanadium and 30% lead and cadmium. The published toxicity limits for bioavailable Cd, Mn, Ni, and Pb were exceeded in 14%, 39%, 10%, and 56% of samples, respectively. The concentrations of pseudo-total total iron, cobalt, chromium, and nickel, and available cobalt, nickel and titanium were significantly lower in soils with gleyic properties (reducing conditions).
Highlights
Soils in urban environments are strongly influenced by man, whose activity is based in these environments
This paper aims to study the concentrations and forms of potentially toxic elements (PTEs) in urban soils in the province of Havana, as a contribution to the knowledge of the quality of these soils, and to identify the possible origin of these elements
The pseudo-total concentrations for most PTEs did not exceed the maximum concentrations allowed in agricultural soils
Summary
Soils in urban environments are strongly influenced by man, whose activity is based in these environments. The anthropogenic influence alters the processes of soil formation, often changing the direction of soil evolution. The human perturbation may vary in intensity, giving rise to a wide range of urban soils from quasi-natural to strongly disturbed soils. Human influence can interfere more or less intensely with the natural processes of soil formation, can provide exogenous materials, including pollutants, and can eventually build new soils by providing organic or mineral materials from which new processes of soil formation will start. Urban soils provide considerable ecosystem services, such as supporting plant growth, including urban agriculture; taking part in biogeochemical cycles; contributing to Environments 2020, 7, 43; doi:10.3390/environments7060043 www.mdpi.com/journal/environments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
