RESUMEN
The COVID-19 pandemic has had a deep impact on the way we perceive our world. This study explores its effect on Urban Green Space (UGS) perception in Buenos Aires City (CABA), Argentina. We provide a detailed overview of the distribution of UGS in CABA, along with socio-economic analysis and visitors' profile and perception before and during the restrictive measures adopted by the national authorities to contain the COVID-19 outbreak (July to December of 2020). We conducted a series of surveys based on open and closed questions. Before the pandemic, surveys were carried out in situ in eight parks of six districts, randomly chosen. During the confinement, online surveys were conducted. According to our results, the mean UGS density in CABA is 6.09 m2 /person, but marked differences between districts exist, ranging from 0.02 m2 /person to 17.68 m2 /person. This uneven distribution causes differences in the quality of life of CABA inhabitants, perhaps more pronounced during reduced-mobility situations like COVID-19 confinement. Socio economic analysis were done linking multidimensional poverty, COVID-19 positive cases and urban mobility in CABA. Regarding UGS visitors, before the confinement, the majority of respondents were employees or students; during the confinement, employees and retirees predominated. When asked to choose important attributes to describe their perception about the UGS from a given list, respondents selected "calm," "green," and "sounds of nature," without differences before and during the confinement. However, when asked about the UGS role, the main answer was "a place to be with nature" before the confinement and "an important place in the city" during it. Understanding how society perceives the UGS, especially during crises, is essential to rethink the urban landscape and prepare our cities, towards biophilic cities and for a more sustainable future.
RESUMEN
In the present work, a remediation bioprocess based on the use of a native isolate of Chlorella vulgaris immobilized in an alginate matrix inside a polylactic acid (PLA) device is proposed. This microalga immobilized in alginate beads was previously shown to be useful for the reduction of several chemical and microbial contaminants present in the highly polluted water from the Matanza-Riachuelo watershed. However, these beads had a relatively short shelf life in the natural environment. To overcome this limitation, a 3D-printed PLA device was designed. PLA is a biocompatible and biodegradable material suitable for biotechnological applications. We used Erlenmeyers and stirred-tank bioreactors fed batch with Murashige Skoog (MS) culture medium or water from the Cildáñez stream (one of the water bodies of the aforementioned watershed) to estimate the growth kinetics parameters and the bioremediation capacity of immobilized-microalgal cells as an unconfined system (UcS) or a confined system (CfS) inside PLA devices on Cildáñez water. Although alga's growth parameters were maximum in the UcS fed with MS medium as substrate, successful bioremediation of the target water was possible using the CfS: all inorganic nitrogen forms and total phosphorus were reduced at least by 90% after 5 days of bioprocess in an agitated bioreactor, whereas aerobic mesophilic bacteria decreased by about 85%. The number of coliforms also decreased. Standardized cytotoxicity tests using Allium cepa seeds carried out to prove the effectiveness of the bioremediation process, confirmed the high degree of decontamination achieved by the use of immobilized microalga confined in a 3D-printable PLA-device.