1,721,025 research outputs found
The weight of human activities on the basin-coast system: the case of Emilia-Romagna Region (Northern Adriatic).
No full textContributo alla conoscenza del clima meteomarino della Sacca di Goro: misure correntometriche e mareografiche
No full text--
Risposte del litorale regionale alle secolari attività antropiche ed ai possibili cambiamenti climatici previsti per i prossimi decenni.
No full textIntegration of microplastic gravimetric separation protocol considering sediment texture and composition
No full textCoastal-lagoon environments are highly vulnerable and subject to multiple stressors, among which marine litter (ML) is a serious global issue. The predominant category of ML recorded along coasts mainly consists of artificial polymeric materials (Le et al., 2024). In the environment, macro-ML degrades into smaller items due to photo-thermo-oxidative degradation: Large Micro Plastics (LMP, 5 - 1 mm), Small Micro Plastic (SMP, 1 mm – 20 μm), nano Plastics (nP, ≤ 20 μm). These microplastics are defined as secondary. However, primary microplastics can also be found in the environment, which are produced in microscopic sizes for specific
purposes and various applications (Saeedi, 2024).
Many protocols have been developed to study and quantify the presence of SMP in various types of coastal
environments. Quantifying SMP along the sandy coasts of the northern Adriatic Sea remains challenging due
to the very fine dimensions of the sediments in which microplastic items are trapped. Therefore, the gravimetric
separation of microplastics from sediments using non-toxic and cost-effective saline solutions presents some
practical difficulties. The protocol conventionally used in the Adriatic area for sampling and analysis of SMP
(Palatinus et al., 2015) suggests adding 200 mL of saturated NaCl solution (density 1.2 g/cm3
) to 50 mL of
sampled sediment. This mixture is then stirred for 2 minutes to suspend the microplastic items embedded in
the sediments. According to the protocol, a waiting time of 4 minutes is required for sediment precipitation,
and then the supernatant can be collected and filtered in order to collect the microplastics on borosilicate glass
fiber filters (Whatman® microfiber filetrs GF/D, mesh size 2,7 μm).
However, the mentioned protocol does not provide information correlating sediment grain size with an
optimal waiting time to perform this procedure. From various tests conducted by our team, it has been observed
that the indicated waiting times are not sufficient to achieve the complete settlement of non-plastic particles,
particularly for samples containing an average of 69% fine sediments, rich in muddy fraction (d < 0.250 mm).
With this work, we suggest a possible integration to the protocol based on preliminary tests useful for
verifying the optimal waiting times for collecting the supernatant to be filtered, in relation to the textural and
compositional characteristics of the sediments. This integration helps to avoid both the deposition of a compact
solid matrix on the filter, which could mask the presence of the microplastics to be observed, and the damage
to the equipment used for vacuum filtration
Implementazione di un metodo di separazione granulometrica gravitazionale
No full textIn questo studio è stato testato un metodo per separare le diverse frazioni granulometriche senza l’utilizzo di agenti chimici, quindi mantenendo inalterate le caratteristiche chimico-fisiche delle varie frazioni separate. Il metodo si avvale del classica separazione umida per dividere la frazione sabbiosa da quella fine (<63 μm).
Mentre le frazioni siltose vengono separate da quelle argillose utilizzando il metodo di separazione gravitazionale in cilindri immersi in un bagno termostatico a 20 °C. Come fase disperdente è stata utilizzata solo acqua deionizzata, il surnatante contenente le particelle di argilla in sospensione è stato sifonato dopo che le frazioni più grossolane hanno sedimentato sul fondo. Il calcolo del tempo di sedimentazione è stato effettuato tramite la legge di Stokes. La procedura è stata testata su 3 repliche di suolo granulometricamnete eterogeneo. I risultati ottenuti confermano il buono grado di riproducibilità del metodo, in quanto la deviazione standard normalizzata risulta inferiore al 5% ed il grado di purezza delle frazioni granulometriche più fini è risultato del 90% per il silt e del 95% Per l’argilla. Questo metodo, semplice ed economico può quindi essere applicato in esperimenti sull’adsorbimento di contaminanti su diverse frazioni granulometriche data l’elevato grado di purezza raggiungibile
Natural and man-made coastal change of the Goro spit-lagoon system (Po Delta, Northern Italy)
No full text- …
