How physical alteration of technic materials affects mobility and phytoavailabilty of metals in urban soils?

Evaluating the effect of historical development on urban soils using microartifacts and geochemical indices

The proposed research is devoted to the effects of the urbanization on the soil cover through the assessment of common organic and inorganic pollutants as well as anthropogenic microartifacts (MAs) over 20 sites characterizing different land use areas within the city of Tyumen, Russia. The analytical methods included measurements of physical-chemical properties of soils (total organic carbon content, pH, and texture), the total concentrations of potentially toxic elements (V, Cr, Co, Ni, Cu, Zn, As, Sr, and Pb) using X-ray fluorescence analysis, and the concentrations of 12 priority polycyclic aromatic hydrocarbons using high-performance liquid chromatography, and the evaluation of the composition of anthropogenic MAs assemblies by optical microscopy. The results of the study showed that the soils of all studied sites within the industrial areas were characterized by a high level of combined pollution with elements and compounds. For other sites, the duration of urbanization was the strongest factor that influenced the levels of pollution. The sites with the highest pollution levels were also characterized by the highest proportion and diversity of MAs. In contrast to the urban soils of the cities in North America and Western Europe, anthropogenic MAs associated with the use of coal (ash, slag, and silicon spheres) were present, but to a far lesser extent. Apparently, this is due to the fairly late development and intensive growth of Tyumen in the second half of the twentieth century, as well as the use of natural gas and fuel oil. At the same time, MAs associated with construction and domestic debris prevailed both in the soils of demolition sites and residential areas, which indirectly indicates the rapid and chaotic nature of urbanization, characteristic of Tyumen.

Effects of Different In Situ Remediation Strategies for an As-Polluted Soil on Human Health Risk, Soil Properties, and Vegetation

The demand for soils for recreational uses, gardening, or others in urban and periurban areas is increasing, and thus the presence of polluted technosols in these areas requires nature-based in situ remediation technologies. In this context, the capacity of three amendments, namely zero valent iron nanoparticles (nZVI), compost and a mixture of compost and biochar, to immobilise As in a polluted technosol simultaneously cultivated with Lolium perenne L. were tested and compared. The characteristics of the soil were comprehensively characterised by chemical and X-ray analysis to determine As contents, distribution, and mineralogy. As mobility was evaluated by the RBA methodology and then potential human health risks, both carcinogenic and non-carcinogenic, were assessed in all treatments. The nZVI treatment reduced risks due to the As immobilisation obtained (41% As decrease, RBA test), whereas the organic amendments did not imply any significant reduction of the RBA values. As to soil properties, the organic treatments applied lowered the pH values, increasing cation exchange capacity, and carbon and nutrient contents. To determine impacts over plant production, fresh biomass, As, Ca, Fe, K, Mg, Na and P were measured in Lolium under the different treatments. Notably, organic amendments improved As extraction by plants (57% increase), as well as fresh biomass (56% increase). On the contrary, nZVI diminished As extraction (65% decrease) and promoted a fresh biomass decrease of 57% due to nutrients immobilisation (61% decrease of P in plants tissues).

Trace Elements in Soils and Vegetables from Market Gardens of Urban Areas in Marrakech City

The consumption of vegetables grown on soils polluted by trace elements can cause a serious threat for animal and human health and disturb the functioning of the ecosystem. The aim of this work is to determine the concentrations of As, Cd, Co, Cr, Cu, Ni, Pb, Mn, and Zn in soils and different vegetables from market gardens of urban areas in Marrakech city in order to investigate human health risk through ingestion of contaminated vegetables. Plant transfer factor (TF), daily intake of metals (DIM), and health risk index (HRI) were calculated. The concentrations of all metals studied in the garden top soils were within the threshold values. The Cu, Zn, Co, Mn, and As concentration in the edible parts of vegetables were within the safe limits. However, Cd and Pb in Malva parviflora and Cd in Brassica rapa, and Cr and Ni in Coriandrum sativum exceeded their permissible limits. The TF for these nine metals varied between 0.01 and 1.35. The classification of TEs according to their TF is as follows: Cu > Zn > Cd > Ni > Cr > Pb > Mn > Co > As. The maximum value was recorded in Coriandrum sativum while the minimum value was recorded in Cynara cardunculus. The HRI values were within the safe limit (< one) except for Pb in Malva parviflora. This can lead to risks to the health of the human population, especially children, consuming contaminated plants. Thus, the monitoring and prevention of health risks related to the consumption of plants grown in (peri)urban areas are necessary and essential to propose recommendations to both gardeners and decision-makers.