Characterization and origin of organic and inorganic pollution in urban soils in Pisa (Tuscany, Italy)

Metals in urban soils of Europe: A systematic review

Metal contamination of soils is widespread across Europe and is of great concern as it may impact food production, the supply of drinking water and human health (European Environment Agency, 2014; Panagos et al., 2013). Most research to date on soil metal contamination has focussed on agricultural soils (Tóth et al., 2016a). Current knowledge of the extent of urban soil metal contamination in Europe, however, is limited, especially for soils in recreational areas, which is particularly concerning as these areas may have a high footfall. Here, we conducted a systematic analysis of metal contamination in European urban soils based on 174 peer-reviewed studies spanning 143 urban sites and 29 European countries. The results show that reporting of data on urban soil metals is highly heterogeneous across the study area. Over half of all studies are from only five countries (Italy, Spain, UK, Poland and Serbia) and no data are available for 14 other European countries. The metals that most commonly exceed national safety thresholds are Pb, Zn, Cu, Cr and Ni. Elevated levels of these metals are usually attributed to anthropogenic sources, primarily traffic and industry. Some 22 % of urban sites studied show anthropogenic enrichment; this phenomenon is most common in Italy, Serbia and Finland. In contrast, 44 % of urban sites studied show geogenic metal enrichment; this is most common in Italy, the UK and Serbia. The dataset is subject to a sample size bias, whereby soil metal enrichment is identified more frequently in regions with more data. Future studies should focus on key knowledge gaps, such as urban soils in locations with current or historical heavy industrialisation and locations in central and eastern Europe. Study methods should be standardised to facilitate comparison of soil metal data from different studies and European safety thresholds should be identified for key elements.

Assessment of sources and pollution state of trace and toxic elements in street dust in a metropolitan city

Street dust and urban soil samples are significant part of environmental compartments to evaluate the contamination levels in urban and industrial zones. This study was carried out to ascertain the concentrations of trace and toxic elements in Izmir street dusts collected from 20 different sites dominating by industrial (four sites), residential (seven sites) and traffic (nine sites) areas, and also to figure out the exposure of adults and children to the elemental toxicity in dust. In order to measure the total and soluble concentrations of elements, the dust samples were analyzed with ICP-MS methodology. The results indicated that concentrations of anthropogenic-based elements are homogenously spread out in whole Izmir city in a similar way to crustal-based elements. This indicates that traffic and residential heating were dominant pollutant sources throughout the city dusts. The health risk assessment showed that elemental non-carcinogenic risks are lower than limit value. However, the cancer risks exceed the acceptable level for As and Cr. According to source apportionment analysis, seven factors were defined for trace elements for all site data.

The Complex Issue of Urban Trees—Stress Factor Accumulation and Ecological Service Possibilities

This review paper is the first that summarizes many aspects of the ecological role of trees in urban landscapes while considering their growth conditions. Research Highlights are: (i) Plant growth conditions in cities are worsening due to high urbanization rates and new stress factors; (ii) Urban trees are capable of alleviating the stress factors they are exposed to; (iii) The size and vitality of trees is related to the ecological services they can provide. Our review shows, in a clear way, that the phenomenon of human-related environmental degradation, which generates urban tree stress, can be effectively alleviated by the presence of trees. The first section reviews concerns related to urban environment degradation and its influence on trees. Intense urbanization affects the environment of plants, raising the mortality rate of urban trees. The second part deals with the dieback of city trees, its causes and scale. The average life expectancy of urban trees is relatively low and depends on factors such as the specific location, proper care and community involvement, among others. The third part concerns the ecological and economic advantages of trees in the city structure. Trees affect citizen safety and health, but also improve the soil and air environment. Finally, we present the drawbacks of tree planting and discuss if they are caused by the tree itself or rather by improper tree management. We collect the latest reports on the complicated state of urban trees, presenting new insights on the complex issue of trees situated in cities, struggling with stress factors. These stressors have evolved over the decades and emphasize the importance of tree presence in the city structure.