Tracking the Pathway of Persistent Organic Pollutants and Plastics from Land to Sea: Analyzing their Presence in Atmospheric Deposition, Urban Dust, and Waterways in Bahía Blanca, Argentina

GIRONES, LAUTARO; VILLAFAÑE, BELEN; POZO, KARLA; ADARO, MARÍA EUGENIA; RONDA, ANA CAROLINA; MARCOVECCHIO, JORGE EDUARDO; ARIAS, ANDRES HUGO

Congreso; 43rd International Symposium on Halogenated Persistent Organic Pollutants (POPs); 2023

Introduction: Bahía Blanca is a coastal city in Argentina known for its industrial and commercial activities, including a petrochemical complex and a deep-water port. The city is surrounded by an estuary which is subject of environmental concern due to pollution resulting from inadequate management of these activities. In this study, our objective was to detect andquantify persistent organic pollutants (POPs) and microplastics (MPs) in various environmental compartments of Bahía Blanca, including sediments and water from waterways, atmospheric deposition, and urban dust.Methods: Sediments were collected from six waterways discharging into the Bahía Blanca estuary, including sewage and industrial discharges, as well as urban (Maldonado and Napostá) and non-urban streams. Atmospheric deposition and urban dust was sampled within the Bahía Blanca city. Water of Napostá and Maldonado streams was sampled along rainy and nonrainy days. Dichloro diphenyl trichloroethane and its metabolites (DDXs), hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), and polychlorinated diphenyls (PCBs) were analyzed using hexane-acetone Soxhlet extraction and clean-up on an acid silica column, and quantification were performed using gas chromatograph coupled to a triple quadrupole mass spectrometer. The MPs separation was performed by flotation with saturated NaCl solution followed by filtration of the supernatant for urban dust, river water and atmospheric deposition samples. The MPs were identified and classified with a stereoscopic magnifying glass.Results: The levels of DDXs, HCHs, PBDEs, and PCBs varied significantly between discharges, showing the highest levels at the sewage discharge area (1.73, 0.24, 1.21, and 3.9 ng/g dry weight, respectively), followed by the urban stream´s outlets. The concentration of MPs in the urban streams ranged from 0 to 19.71 MPs/L, with an average of 6.36 MPs/L. During rainy andnon-rainy days, the average estimated mass flow was 140,000 MPs/s (SD: 120,000) and 3,000 MPs/s (SD: 2,900), respectively. Urban dust levels ranged from 14.65 to 205.86 MPs/kg (mean of 60.92 MPs/kg), and MPs amount were significantly lower fewhours after the rainfall. Atmospheric deposition of MPs ranged from 0 to 86.81 MPs/m2/day (mean of 18.1 MPs/m2/day). The average size of plastic particles in urban dust, watercourses, and atmospheric deposition was 1.11-1.38 mm, with no significant difference between the compartments. Fibers were the dominant shape of plastics in the three environmental compartments, with average proportions of 89%, 85%, and 55% in stream water, atmospheric deposition, and urban dust, respectively, while fragments had mean values of 9%, 11%, and 38% in the same compartments.Discussion and Conclusion: The concentrations of POPs in the sediments of the urban streams were higher than those found inthe Bahia Blanca estuary, and positively correlated with levels observed in the coasts near each discharge in previous studies [1,2,3]. This point at these discharges as the main sources of POPs to the estuary. Analysis of plastics as POP carriers from the urban area is therefore relevant, and appropriate management could improve environmental quality in the estuary and beyond.The study revealed that the main source of plastics reaching the estuary is through surface runoff from storm water, with the plastics found in water, air, and urban dust having similar shapes and sizes. While previous studies have shown an association between POPs and plastics in the estuary [3], it is still unclear if the plastics found in the air, urban dust, and stream water areindeed carriers of POPs, and further research will be conducted in this direction. Overall, the study emphasizes the need for improved environmental management practices and additional research to better understand the sources and fate of these pollutants in the estuary. The presence of POPs and MPs in various environmental compartments underscores the urgency of addressing this issue to ensure the long-term sustainability of this critical ecosystem.