Assessment of sulfonamide contamination in aquatic environments: A first report for Argentina and environmental risk assessment.

The global surge in pharmaceutical consumption, driven by increasing population and the demand for animal proteins, leads to the discharge of diverse pollutants, including antibiotic residues, into water bodies. Sulfonamides, being water-soluble compounds, can readily enter surface run-off, posing potential risks to non-target species despite their low environmental concentrations. Latin America has implemented intensive production systems highly dependent on antimicrobials for productivity and animal health, yet there is a paucity of information regarding their concentration in the region. The objective of this study was to evaluate the presence of sulfonamides in water and sediment samples and assess their potential ecological risks through an environmental risk assessment. The Río de la Plata basin collects the waters of the Paraguay, Paraná, and Uruguay rivers, together with their tributaries and various wetlands, passing through the provinces in Argentina known for their significant animal husbandry production. Two sampling campaigns were carried out for sediment, while only one campaign was conducted for surface waters. The samples were analyzed by high performance liquid chromatography tandem mass-spectrometry (HPLC-MS/MS). None of the examined sulfonamide antibiotics were detected in the sediment samples from both sampling campaigns. In contrast, sulfadiazine (95 %), sulfamethoxazole (91 %), and sulfathiazole (73 %) were detected in the water samples. Sulfadiazine was found in the concentration range of 8 to 128 ng/L, while sulfamethoxazole and sulfathiazole were observed at concentrations ranging from 3.0 to 32.5 ng/L and 2.9 to 8.1 ng/L, respectively. Based on the environmental risk assessment conducted using the sulfonamide concentrations, most samples indicated a medium risk for aquatic biota, with only one sample surpassing the high-risk threshold. This study represents the first report presenting data on the presence of sulfonamide antibiotics in the aquatic environment of Argentina.

First evidence of environmental bioaccumulation of pharmaceuticals on adult native anurans (Rhinella arenarum) from Argentina.

The presence of pharmaceutically active compounds (PhACs) in surface water is well known, whereas their natural occurrence in biota is much less explored. The aim of this work was to evaluate the bioaccumulation of PhACs in adult toads of the neotropical species Rhinella arenarum. Three sites were selected in Buenos Aires (Argentina): a reference site (Site 1), a site with direct discharge from a secondary wastewater treatment plant (WWTP) (Site 2) and a site 300 m downstream of the WWTP discharge (Site 3). Surface water samples, as well as muscle, liver and fat bodies of toads were collected, extracted and analyzed by LC-MS/MS. Highly significant differences in total PhACs concentration in surface water (p < 0.005) were detected between Site 2 and the other sites. These concentrations ranged from 0.37 to 52.46 ng/L at Site 1, 0.71-6950.37 ng/L at Site 2, and 0.12-75.45 ng/L at Site 3. In general, bioaccumulation of PhACs in toad tissues was similar between sites and tissues of each site. The highest concentrations were detected in the muscle of toads from Site 3 (1.06-87.24 ng/g dw), followed by liver (1.77-38.10 ng/g dw) and fat bodies (0.68-20.59 ng/g dw) from Site 1. Ibuprofen (6950 ng/L), acetaminophen (3277 ng/L) and valsartan (2504 ng/L) were the compounds with the highest concentrations in surface water from Site 2, whereas acetaminophen (87.2 ng/g dw, muscle from Site 3), desloratadine (38.1 ng/g dw, liver from Site 1), and phenazone (25.9 ng/g dw, liver from Site 1) were the ones that showed the highest concentrations in biota. This is the first time a field study has examined the environmental bioaccumulation of PhACs in anurans, demonstrating their potential for monitoring the status of natural ecosystems.

Occurrence and levels of glyphosate and AMPA in shallow lakes from the Pampean and Patagonian regions of Argentina.

Glyphosate (N-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide used to kill weeds that compete with commercial crops. In Argentina, the use of glyphosate-based herbicides increased dramatically (up to ∼200,000 tons on 2012) since the introduction of glyphosate-resistant crops, such as transgenic soy and resistant corn, and the adoption of non-till practices in the 1990's. Sallow lakes within the Pampa region may be potentially impacted by continuous herbicide usage. We surveyed 52 shallow lakes from the Pampa region (Buenos Aires Province, Argentina) to assess the occurrence and concentrations of glyphosate and its main degradation product (AMPA). For comparison, we also sampled 24 shallow lakes from an area with no agricultural use of glyphosate (Northern Patagonia). Glyphosate and AMPA were analyzed by UPLC-MS/MS ESI (±) in lake water, suspended particulate matter (SPM), and sediment samples. Within the Pampa region, glyphosate residues were detected in >40% of samples. Glyphosate residues were detected more frequently in sediment and surface water than in SPM samples. The mean (maximum) concentrations of glyphosate were 2.11 (4.52) µg l-1 for surface water; 0.10 (0.13) µg l-1 for SPM and 10.47 (20.34) µg kg-1 for sediment samples, respectively. Whereas, mean (maximum) concentrations of AMPA were 0.84 and (0.90) µg l-1 for surface water; 0.07 (0.07) µg l-1 for SPM; and 22.53 (32.89) µg kg-1 for sediment samples. The herbicide was not detected in samples from the Patagonian region. To our knowledge, this is the first study reporting the occurrence and concentrations of the herbicide in freshwater lakes of Argentina.

Water quality of the main tributaries of the Paraná Basin: glyphosate and AMPA in surface water and bottom sediments.

The Paraná River, the sixth largest in the world, is the receptor of pollution loads from tributaries traversing urban and industrialized areas plus agricultural expanses, particularly so in the river's middle and lower reaches along the Argentine sector. In the present study, we analyzed and discussed the main water quality parameters, sediment compositions, and content of the herbicide glyphosate plus its metabolite aminomethylphosphonic acid (AMPA) in water and sediments. Samples were obtained from distal positions in the principal tributaries of the Paraná and the main watercourse during surveys conducted in 2011 and 2012 to monitor the basin. Only 15 % of the water samples contained detectable concentrations of glyphosate at an average concentration of 0.60 µg/L, while no detectable levels of AMPA were observed. The herbicide and metabolite were primarily present in sediments of the middle and lower stretch's tributaries, there occurring at a respective average of 37 and 17 % in samples. The mean detectable concentrations measured were 742 and 521 µg/kg at mean, maximum, and minimum glyphosate/AMPA ratios of 2.76, 7.80, and 0.06, respectively. The detection of both compounds was correlated with the presence of sulfides and copper in the sediment matrix.