Butylone (BTL) is a chiral synthetic cathinone available as a racemate and reported as contaminant in wastewater effluents. However, there are no studies on its impact on ecosystems and possible enantioselectivity in ecotoxicity. This work aimed to evaluate: (i) the possible ecotoxicity of BTL as racemate or its isolated (R)- and (S)- enantiomers using Daphnia magna; and (ii) the efficiency of advanced oxidation technologies (AOTs) in the removal of BTL and reduction of toxic effects caused by wastewaters. Enantiomers of BTL were obtained by liquid chromatography (LC) using a chiral semi-preparative column. Enantiomeric purity of each enantiomer was > 97 %. For toxicity assessment, a 9-day sub-chronic assay was performed with the racemate (at 0.10, 1.0 or 10 μg L
Antibiotics are often applied in aquaculture to prevent fish diseases. These substances can cause disturbances on receiving waters, when not properly eliminated from the aquaculture effluents. In this work, ozone (O3) was investigated as a possible oxidizing agent to remove fishery antibiotics from aquaculture effluents: florfenicol (FF), oxytetracycline (OTC), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and trimethoprim (TMP). Batch experiments were performed using ultrapure water and aquaculture effluents spiked with a mixture of target antibiotics at relatively high concentrations (10 mg L-1 each). OTC, SMX and TMP were fully removed (< 30 min) regardless of the tested conditions, mainly by O3 direct attack. In contrast, FF was partially removed in 30 min (∼ 10 and 60%, in aquaculture effluents and ultrapure water, respectively), but only in the presence of hydroxyl radicals (HO•), the FF concentrations reaching levels below the detection limits in ultrapure water after 60 min. In the case of SDM, its degradation was highly influenced by the selected water matrix, but with removals always higher than 68%. In continuous-flow experiments applying more environmentally relevant antibiotic concentrations (100 ng L-1 each) and low O3 doses (1.5 mg L-1), ozonation highly removed (> 98%) all tested antibiotics from aquaculture effluents with a hydraulic retention time (HRT) of 10 min, except FF (68%). Although by-products were detected in treated samples, zebrafish (Danio rerio) embryotoxicity tests did not show a toxicity increase by applying this ozonation treatment. Ozonation is thus a possible solution to remove antibiotics from aquaculture effluents. Still, full-scale studies in aquaculture farms are needed, and generation of HO• may be favoured to readily oxidize the FF antibiotic.
This article presents a comprehensive dataset of physicochemical data from two urban estuaries on the northern Portuguese coast, based on five sampling campaigns conducted between October 2021 and November 2022. The dataset includes: a) in-situ vertical profiles of water physicochemical parameters (temperature, salinity, pH, turbidity, dissolved oxygen concentration and saturation) collected at 8 sampling stations along the Lima estuary (during both ebb and flood tides) and at 11 stations along the Douro estuary (during flood tides); and b) chemical analyses data, including nutrients (nitrate, nitrite, phosphate, ammonium, and silica), chlorophyll a, total particulate matter, particulate organic matter, and key metal (copper, zinc, cadmium, iron, nickel, lead, manganese, and chromium) concentrations. For the Lima estuary, additional data on dissolved metals concentrations are provided, offering a detailed picture of metal contamination. This dataset provides valuable insights into the estuarine dynamics of two important temperate systems, with a particular focus on anthropogenic influences such as nutrient enrichment and metal contamination. The data have strong reuse potential in environmental monitoring, providing a baseline for assessing anthropogenic changes and offering quality-assured references for studies linking contaminant distribution with hydrodynamic patterns in estuarine environments. Furthermore, such data are relevant to supporting the implementing of environmental policies, such as the EU Water Framework Directive for transitional waters.
Estuaries along with their saltmarshes are extremely relevant areas to what ecosystems conservation is concerned. Not only do they provide unique conditions to house numerous species but can also play an important role in pollution mitigation. This study aimed to evaluate the role of saltmarsh plants in metals retention in the long term, using a previously monitored estuary as a case study (Lima river estuary). Seasonal sampling campaigns were carried out in 2022 to determine the metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) concentrations in vegetated and non-vegetated sediments, as well as in salt marsh plants at three sites within the estuarine area, Canogem, Salinas and Srª das Areias. Results showed saltmarsh plants, despite some seasonal variability, are concentrating metals in their rhizosediments (ratio metal in vegetated sediment / metal in non-vegetated sediment >1) and in their roots, namely Cd, Cu and Zn (ratio metal in plant roots / metal in non-vegetated sediment >1). This role seems to be maintained in the long term, with plant metal retention levels similar in 2009 and 2022, indicating plants are probably contributing to remove metals from the surface water. However, this feature seems to be decreasing in one of the sites, Srª das Areias, that showed signs of degradation. Thus, saltmarsh plants have the potential to retain metals in estuarine areas, contributing to reduce metals present in the aquatic environment and preventing them from spreading through the estuarine area, from reaching coastal areas and eventually from reaching underlying aquifers. Protection of this environment is mandatory and the promotion of re-vegetation of non-vegetated estuarine areas is needed so that the saltmarsh works as a nature-based solution that prevents and/or recovers impacted environments, in order that saltmarshes can continue to deliver their multiple co-benefits.
Over the past years, there has been an increasing concern about the occurrence of antineoplastic drugs in water bodies. The incomplete removal of these pharmaceuticals from wastewaters has been confirmed by several scientists, making it urgent to find a reliable technique or a combination of techniques capable to produce clean and safe water. In this work, the combination of nanofiltration and ozone (O3)-based processes (NF + O3, NF + O3/H2O2 and NF + O3/H2O2/UVA) was studied aiming to produce clean water from wastewater treatment plant (WWTP) secondary effluents to be safely discharged into water bodies, reused in daily practices such as aquaculture activities or for recharging aquifers used as abstraction sources for drinking water production. Nanofiltration was performed in a pilot-scale unit and O3-based processes in a continuous-flow column. The peroxone process (O3/H2O2) was considered the most promising technology to be coupled to nanofiltration, all the target pharmaceuticals being removed at an extent higher than 98% from WWTP secondary effluents, with a DOC reduction up to 92%. The applicability of the clean water stream for recharging aquifers used as abstraction sources for drinking water production was supported by a risk assessment approach, regarding the final concentrations of the target pharmaceuticals. Moreover, the toxicity of the nanofiltration retentate, a polluted stream generated from the nanofiltration system, was greatly decreased after the application of the peroxone process, which evidences the positive impact on the environment of implementing a NF + O3/H2O2 process.
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