International Journal of Environmental Research and Public Health Article Assessment of Soil Contamination with Potentially Toxic Elements and Soil Ecotoxicity of Botanical Garden in Brno, Czech Republic: Are Urban Botanical Gardens More Polluted Than Urban Parks? Vaclav Pecina 1,2 , Martin Brtnicky 1,2,3,* , Marie Balkova 3 , Jitka Hegrova 4 , Martina Buckova 4, Tivadar Baltazar 2 , Roman Licbinsky 4 and Maja Radziemska 2,5,* 1 Faculty of Chemistry, Institute of Chemistry and Technology of Environmental Protection, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic; [email protected] 2 Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrition, Faculty of AgriSciences, Mendel University in Brno, Zemedelska 1, 613 00 Brno, Czech Republic; [email protected] 3 Department of Geology and Soil Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic; [email protected] 4 Transport Research Centre, Lisenska 33a, 636 00 Brno, Czech Republic; [email protected] (J.H.); [email protected] (M.B.); [email protected] (R.L.) 5 Institute of Environmental Engineering, Warsaw University of Life Sciences, 159 Nowoursynowska, Citation: Pecina, V.; Brtnicky, M.; 02-776 Warsaw, Poland Balkova, M.; Hegrova, J.; Buckova, * Correspondence: [email protected] (M.B.); [email protected] (M.R.); M.; Baltazar, T.; Licbinsky, R.; Tel.: +420-607-036-907 (M.B.); +48-2259-353-70 (M.R.) Radziemska, M. Assessment of Soil Contamination with Potentially Toxic Abstract: Though botanical gardens are an important and widely visited component of urban green Elements and Soil Ecotoxicity of spaces (UGS) worldwide, their pollution is rarely studied. The aim of this study was to assess Botanical Garden in Brno, Czech botanical garden soil contamination and ecotoxicity and to evaluate whether urban botanical gardens Republic: Are Urban Botanical are more contaminated than urban parks. Soil assessments showed serious contamination with Cd, Gardens More Polluted Than Urban Pb and Zn, emitted predominantly by traffic, agrochemicals and past construction and demolition Parks? Int. J. Environ. Res. Public Health 2021, 18, 7622. https:// waste. The discovery of hazardous historical ecological burden in the UGS calls for the necessity of doi.org/10.3390/ijerph18147622 detailed surveys of such areas. Despite prevailing moderate-to-heavy contamination, the soil was only slightly ecotoxic. Maximum immobilisation inhibition of Daphnia magna reached 15%. Growth Academic Editors: Bozena Smreczak, of Sinapis alba L. was predominantly stimulated (73%), and Desmodesmus subspicatus Chodat was Alicja Kicinska, Eleonora Wcisło and exclusively stimulated, possibly due to soil alkalinity and fertiliser-related nutrients. The hypothesis Giulia Maisto of a higher contamination of urban botanical gardens compared to urban parks was confirmed. However, urban parks can face a greater risk of soil ecotoxicity, hypothetically due to decreased Received: 21 April 2021 activity of soil organisms resulting from adverse soil conditions caused by active recreation. The Accepted: 14 July 2021 results highlight the need for an increased focus on botanical and ornamental gardens when assessing Published: 17 July 2021 and managing UGS as areas potentially more burdened with contamination. Publisher’s Note: MDPI stays neutral Keywords: urban green spaces; ornamental garden; soil toxicity; construction and demolition waste; with regard to jurisdictional claims in contamination; risk assessment published maps and institutional affil- iations. 1. Introduction Urban soil pollution by anthropogenic activities is an important research topic [1,2]. Copyright: © 2021 by the authors. Reduced soil quality poses a risk to human health and urban ecosystems [3–6]. Typically, Licensee MDPI, Basel, Switzerland. This article is an open access article soil in industrial areas or near roads contains the highest pollution levels due to the distributed under the terms and continuous emission of potentially toxic elements (PTEs) [7,8]. Industry, traffic [9,10] and conditions of the Creative Commons coal combustion [4,10] emit high concentrations of PTEs and represent the most important Attribution (CC BY) license (https:// sources of pollution in cities. creativecommons.org/licenses/by/ Urban green spaces (UGS) and their soils are an essential component of urban ecosys- 4.0/). tems [3,11,12]. They improve city dwellers’ living conditions through functions such as Int. J. Environ. Res. Public Health 2021, 18, 7622. https://doi.org/10.3390/ijerph18147622 https://www.mdpi.com/journal/ijerph Int. J. Environ. Res. Public Health 2021, 18, 7622 2 of 13 climate regulation, sustaining biogeochemical cycles, water flow regulation, runoff mitiga- tion and pollutant retention [6,11,13–15]. UGS are often considered less polluted [16,17] and sometimes even used to determine background values for environmental contamination assessment [18,19]. However, due to their potential to retain and store pollutants, they may become hotspots of accumulated pollution. PTEs bind to the soil organic matter [1] of UGS and remain persistent in soil [20]. When assessing UGS pollution with PTEs, great attention is paid to public urban parks (e.g., Setälä et al. [6]; Urrutia-Goyes et al. [21]; Gu et al. [22]; Brtnický et al. [23]; Han et al. [24]). However, research rarely focuses on arboretums, botanical and ornamental gardens [10,25], despite their worldwide prevalence in urban areas and importance to local communities. Botanical gardens and arboretums represent artificial but stable environments [26]. They were first introduced in the 16th century. There are 1775 registered in 148 countries according to the current definition of Botanic Gardens Conservation International [27], and more than 3000 have been registered according to the previous definition [28]. In addition to their focus on scientific research, conservation and education, botanical gardens and arboretums are popular tourist sites visited by approximately 500 million visitors per year [27] with a strong social relevance [29,30]. Cavender and Donnelly [13] even urge their increased involvement with urban forestry to improve sustainability of cities and human lives. The greater focus on urban parks research may be due to residents’ higher frequency of visits, thus increasing the risk of exposure to soil pollutants. Additionally, the possibility of direct contact with contaminated soil is usually less likely in botanical gardens owing to the different nature of activities. Active and regular management of botanical gardens through fertilisers and various pesticides [9,25,26], on the other hand, can result in a higher risk of soil contamination. For example, Orecchio [31] found botanical garden soil contaminated with polycyclic aromatic hydrocarbons. Similarly, the potential of a higher load of PTEs in ornamental gardens was indicated by Biasioli et al. [32]. Martín et al. [10] even refer to botanical gardens as excellent tools to evaluate pollution. Thus, despite the lower risks to visitors, botanical gardens can hypothetically be more hazardous contamination hotspots of PTEs in urban areas. To verify this hypothesis, several sub-steps were performed: (1) assessment of soil contamination with PTEs (As, Cd, Cr, Cu, Ni, Pb and Zn) in the botanical garden, (2) as- sessment of the spatial distribution of PTEs, (3) assessment of the soil ecotoxicity and (4) comparison of the contamination of botanical and ornamental gardens to urban parks. 2. Materials and Methods 2.1. Study Site The studied botanical garden (and arboretum) is located in Brno, Czech Republic, at an altitude of 220–250 m a. s. l. in an area with an average total precipitation of approximately 550 mm/year and average annual temperature of 8.4 ◦C. The soil is primarily clayey with a high CaO content or artificial batch formed after clay mining. The arboretum was founded in 1938 on two hectares and was extended to eleven hectares in 1967. Until then, the area had a predominantly agricultural use. The lower section of the garden was adjacent to the construction landfill, and demolition waste remained after the bombing of the city during World War II. The northern section was bordered by an allotment and an agricultural area. Currently, a university campus, a dormitory, a sports area, an unmanaged green space, roads and tram tracks surround the garden. The garden grounds include an administrative building with classrooms, greenhouses and water features. It serves as a purpose-built educational facility and is also used by students for recreation and relaxation. 2.2. Soil Sampling and Laboratory Analysis A total of 37 samples were collected from the botanical garden topsoil (0–5 cm), and two comparative samples were collected near the road and tram stops outside the garden. The Int. J. Environ. Res. Public Health 2021, 18, x 3 of 15 Int. J. Environ. Res. Public Health 2021, 18, 7622 3 of 13 2.2. Soil Sampling and Laboratory Analysis A total of 37 samples were collected from the botanical garden topsoil (0–5 cm), and two comparative samples were collected near the road and tram stops outside the garden. samplesThe samples were were taken taken from thefrom regular the regular sampling sampling network network with a with 5 m spacing a 5 m spacing (Figure (Figure1). Three 1). subsamplesThree subsamples within a within radius ofa 0.5radius m from of 0.5 the m sampling from the point sampling were collected