This field study aimed to assess the base line conditions of a long-term polluted shooting range in Argentina polluted with 428 mg kg-1 lead (Pb), to evaluate the establishment and development of Helianthus petiolaris plants and address the efficacy of the phytomanagement strategy through: i) element accumulation in plant tissues; ii) rhizosphere bacterial diversity changes by Illumina Miseq™ and iii) floral water and essential oil yield, composition and element concentration by GC-MS and ICP. After one life cycle growing in the polluted sites, in the roots of Helianthus petiolaris plants Pb concentration was between 195 and 304 mg kg-1 Pb. Only a limited fraction of the Pb was translocated to the aerial parts. The predominance of the genus Serratia in the rhizosphere of Helianthus petiolaris plants cultivated in the polluted sites and the decrees of the essential oil yield were some effects significantly associated with soil Pb concentration. No detectable Pb concentration was found in the floral water and essential oil obtained. Extractable Pb concentration in the soil reduced between 28-45 % after the harvest.

Both, in developed and developing countries, atmospheric pollution with particulate matter (PM) remains an important issue. Despite the health effects of poor air quality, studies on air pollution are often limited by the high costs of continuous monitoring and the need of extensive sampling. Furthermore, these particles are often enriched in potentially toxic trace elements and organics pollutants. This study evaluates both, the composition of atmospheric dust accumulated during a certain time-span on leaves of Hedera helix and Senecio cineraria, as well as the potential to use them as bio-monitors. The test plants were positioned nearby automatic air quality monitoring stations at four different sites with respectively high, moderate and low traffic intensity. Gravimetric deposition of PM10 and PM2.5 on leaves was consistent with data recorded by the monitoring stations and related to the weather conditions reported by Argentina´s National Meteorological service. To determine the presence of trace elements enriching the PM deposited on leaves, two analytical techniques were applied, XRF (not destructive) and ICP (destructive). The results indicated that only in the unpaved street location (site 2), PM10 and PM2.5 concentrations in the air exceeded WHO guidelines. However, several trace elements were found enriching PM deposited on leaves from all sites. Predominantly, increased concentrations of Cd, Cu, Ti, Mn, Zn and Fe were found, which were associated to construction, traffic and unpaved street sources. Furthermore, based on its high capability to sequester PM and trace elements Senecio cineraria can be take into consideration to be adopted as a bio-monitor or even for PM mitigation.

Extensive green roofs provide for many ecosystem services in urban environments. The efficacy of these services is influenced by the substrate characteristics and vegetational composition. Despite their key role in plant performance and productivity, or their contribution to nitrogen fixation or carbon sequestration, green roof microbial communities have received little attention so far. Here, we investigated whether microbial communities in extensive green roof substrates contain a core community, as well as whether they are affected by green roof plant diversity. Eleven green roofs, planted either with a mixture of grasses, wildflowers and succulents (Sedum spp.), or solely species of Sedum, were seasonally sampled to investigate prokaryotic and fungal communities via metabarcoding. Although Sedum-herbs-grasses roofs contained more plant species, we observed no discriminant microbial communities between both roof types, likely due to sharing the same substrate textures and the vegetational layers that became more similar throughout time. Examining key microbial taxa revealed that most taxa are also dominant phylotypes in soils across different biomes. Many bacterial core taxa are capable of nitrogen fixation and most fungal key taxa are stress-tolerant saprotrophs, endophytes, or both. Microbial community composition further revealed high similarities with aerial samples taken in urban environments. Considering the extreme edaphic conditions that periodically arise in green roof substrates, further investigation is warranted to determine the extent to which the dynamic and intriguing microbial communities are influenced by the aeromicrobiome.