Heavy Metals Contamination of Urban Soils—A Decade Study in the City of Lisbon, Portugal

Abstract

There is an intense and continuous growth of the world population living in cities. This increase in population means an increase in car traffic, an increase in new constructions and an increase in the production of waste that translates into an intensive use of land, particularly in terms of soil contaminants. Among other environmental contaminants, toxic metals, such as lead (Pb), cadmium (Cd), nickel (Ni) and chromium (Cr) represent a public health problem. In this study the content of toxic metals in Lisbon’s (Portugal) soils was determined. The study was conducted over approximately a decade in six city locations, with a total of about 700 samples. Each site has different urban characteristics: traffic zone, residential area, urban park and mixed areas. The study allowed to verify the heterogeneity of metal content values in the city soils and their dependence on local traffic. Metal contents were determined by graphite furnace atomic absorption spectroscopy (GFAAS). For each site the geo-accumulation index, pollution factor, degree of contamination, pollution load index and ecological risk factor were calculated. The mean concentrations of Cd, Cr, Ni and Pb in soils were 0.463, 44.0, 46.6 and 5.73 mg/kg of dry soil, respectively. In the last year of the study the values were 0.417, 51.5, 62.4 and 8.49 mg/kg of dry soil, respectively. Cd and Ni exceeded the typical content values of these metals in the earth’s crust, indicating their anthropogenic origin. The correlation analysis revealed a significant correlation between Cr and Ni, Cd and Ni and Cd and Pb contents in the city soils. Regarding the results obtained in this long monitoring campaign, Lisbon’s soils can be considered as having low levels of pollution by these metals.

Chemical Fractionation, Environmental, and Human Health Risk Assessment of Potentially Toxic Elements in Soil of Industrialised Urban Areas in Serbia

“…When comparing results of PTEs content obtained in this research with results from our previous research [4,73], levels of Mn were found to be similar, but Cr, Cu, Ni, Pb, and Zn concentrations were higher. On the other hand, Cr, Cu, Pb, and Zn content in soils in Novi Sad [74], Lisbon [79], and Thessaloniki [73] was similar, but Ni was somewhat lower than the levels measured in this research (Table 2). Similarities in terms of PTE content were also found in soils from Šabac [75] and Kragujevac [76], where concentrations of most of the examined elements were similar to those determined in this research, with the exception of the higher content of Cr in Kragujevac and Mn in Šabac.…”

Assessments of the Ecological and Health Risks of Potentially Toxic Metals in the Topsoils of Different Land Uses: A Case Study in Peninsular Malaysia

“…The use of Igeo in the soils has been widely reported in literature recently, including Guangzhou-Foshan urban soils of South China [ 45 ], Anshan industrial city (Northeast China) [ 21 ], a municipal solid waste dump in Uyo (Nigeria) [ 49 ], ithallium mining area of southwest Guizhou (China) [ 50 ], Harran Plain (Turkey) [ 51 ], trailer park in Nigeria [ 28 ], Houzhai River Watershed of Guizhou Province (China) [ 46 ], wheat cultivated and natural soils of pastoral lands in the Bai Cheng Region (Xinjiang, China) [ 52 ], Zhundong mining area in Xinjiang [ 53 ], a Ramsar site (Deepor Beel) (Guwahati, India) [ 54 ], Panzhihua (China) [ 55 ], and the city of Lisbon (Portugal) [ 56 ].…”

“…The use of ER and PERI has been widely reported in literature recently such as in polluted farmland soils from China [ 67 ], Guangzhou-Foshan urban soils of South China [ 45 ], Recife metropolitan region in Brazil [ 68 ], industrial area of Hyderabad (India) [ 61 ], iron ore mining in Pahang, Malaysia [ 69 ], in Anshan industrial city (Northeast China) [ 21 ], a municipal solid waste dump in Uyo (Nigeria) [ 62 ], paddy soils of Omor Rice Field, Nigeria [ 62 ], thallium mining area of southwest Guizhou (China) [ 50 ], Harran Plain (Turkey) [ 51 ], trailer park in Nigeria [ 28 ], a copper smelter in Khatoon Abad (Iran) (Nematollahi et al 2020), Houzhai River Watershed of Guizhou Province (China) [ 46 ], Kpone landfill site (Ghana) [ 63 ], wheat cultivated and natural soils of pastoral lands in the Bai Cheng Region (Xinjiang, China) [ 52 ], Zhundong mining area in Xinjiang [ 53 ], a Ramsar site (Deepor Beel) (Guwahati, India) [ 54 ], Panzhihua (China) [ 55 ], Southern Yunnan Province (China) [ 64 ], and the city of Lisbon (Portugal) [ 56 ].…”

Contamination Levels and the Ecological and Human Health Risks of Potentially Toxic Elements (PTEs) in Soil of Baoshan Area, Southwest China

“…Anthropogenically, the soil has been contaminated by fast industrial expansion and subsequent effluent discharge or exhaust emissions, agricultural fertilizers and pesticides, mining operations, population explosions, and subsequent urban dwelling pollution [6,[38][39][40][41][42][43][44][45]. Anthropogenic activities are generally regarded as being the primary source of PTEs in the soil in highly developed, urbanized and industrial urban areas [46][47][48][49], mining areas [5,[50][51][52], or agricultural sectors [41,53]. However, a large body of research on this subject supports the importance of the geological background in contributing to higher PTE contents in soil [2,[33][34][35][36][37]54,55].…”