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An old industrial site (brownfield) located south of Paris in a flooding plain and containing demolition disposal as well as a burning zone for metal recovery is being regenerated to satisfy local need for public green space. The main objective of the described study was therefore to assess the risk of remobilisation of trace metals, PAH and PCB present. The research focused on vertical migration due to rainfall (non-saturated flow) and to river flooding (saturated flow). To assess the remobilisation risk, representative soil profiles were reconstituted and eluted in columns with artificial rain and filtered river water for 6 weeks with an equivalent of 25 mm d−1. Soil analysis showed that both zones are highly contaminated, exceeding the French environmental standards. Though the superficial metal content was much higher in the burning zone with levels of g kg−1 than that in the demolition zone, most metals showed higher levels in the eluents of the latter. The level of dissolved Zn in the burning zone eluent was 30 μg L−1, while in the demolition zone, it was 300 μg L−1, 40 times the admissible level. Zn was thereby correlated to aromaticity parameter HIX, indicating a link with organic matter transformation. The Cu was only significantly released under saturated condition (up to 80 μg L−1) in the demolition soil, indicating as implicated mechanism manganese and iron oxide reduction rather than organic matter transformation. Despite the high PAH and PCB soil contents, these pollutants were not released. The total PAH content in the effluent was 30 ng L−1 in average and did not significantly differ between the two zones and the types of hydrology. Only Zn and Cu issued from demolition zone presented an eco-toxicological risk. Crossed statistical analysis of the results showed that the role of the soil type is preponderant in the pollutant release and that temporary flooding condition would induce a lower impact on the groundwater quality than an equivalent amount of fallen rain. Though the burning site was far more contaminated in the upper soil than the demolition zone, it presented little risk compared to the demolition zone, more profound and more permeable. The latter showed therefore significative trace metal release, up to 2.1 kg ha−1 year−1 for zinc, doubling the local atmospheric deposition. [ABSTRACT FROM AUTHOR]

Due to its multiple functions, urban green is nowadays seen as a possible solution to mitigate global changes, getting so more attention from urban planners. This article develops a systemic function approach through a green intensity index with validation in two characteristic urban areas of Paris conurbation. Their vegetation was qualified and quantified with a shortened species classification system, based on three vertical layers, using field visits, remote sensing and street imagery. The collected data were transformed into urban green intensity index (UGII), using simplified functions based on species number, leaf surface and soil occupation for the five main functions of urban green as identified through bibliometric analysis: hydrology, climate, biodiversity, well-being and air pollution. Central city parts of the metropolis scored hereby low (UGII 3.7–8.9%) due to low biodiversity and absence of infiltration surface, while the suburbs with more green obtained higher values (UGII 36–38%), thanks to better biodiversity and more green per inhabitant. The proposed index allows a rapid assessment of urban green present and classification of three different types of neighbourhood according to their particular green functions biodiversity, hydrology and well-being. Moreover, the differentiation between public and private sectors makes it possible to assess the contribution of public green to the quality of the living environment, while incorporation of species in the index differentiates summer from winter cover, enabling adjustment of municipal green policies. [ABSTRACT FROM AUTHOR]