• Energy Research

The presence of estrogenic mycotoxins, such as zearalenone (ZEN), in surface waters is an emerging environmental issue. Little is known about its phototransformation behavior, which may influence its environmental fate. In this context, the phototransformation of ZEN was investigated in pure water, river water and estuarine water using simulated sunlight irradiation. Kinetic studies revealed that two concomitant processes contribute to the fate of ZEN under solar irradiation: photoisomerization and photodegradation. This phototransformation followed a pseudo-first order kinetics. ZEN degrades quickly in natural waters and slowly in deionized water, with half-lives (t1/2) of 28 ± 4 min (estuarine water), 136 ± 21 min (river water) and 1777 ± 412 min (deionized water). The effects of different water constituents on the phototransformation of ZEN in aqueous solution have been assessed (NaCl, Ca2+, Mg2+, Fe3+, NO3- and oxalate ions, synthetic seawater, Fe(III)-oxalate and Mg(II)-oxalate complexes, humic acids, fulvic acids and XAD-4 fraction). In the presence of synthetic seawater salt (t1/2 = 18 ± 5 min) and Fe(III)-oxalate complexes (t1/2 = 61 ± 9 min), the transformation rate increased considerably in relation to other water constituents tested. The solution pH also had a considerable effect in the kinetics with maximum transformation rates occurring around pH 8.5. These results allow us to conclude that phototransformation by solar radiation can be an important degradation pathway of ZEN in natural waters.

The negative effects induced in marine organisms by Climate Change related abiotic factors consequences, namely ocean warming, are well-known. However, few works studied the combined impacts of ocean warming and contaminants, as pharmaceutical drugs. Carbamazepine (CBZ) and cetirizine (CTZ) occur in the marine environment, showing negative effects in marine organisms. This study aimed to evaluate the impacts of ocean warming on the effects of CBZ and CTZ, when acting individually and combined (drug vs drug), in the edible clam Ruditapes philippinarum. For that, drugs concentration, bioconcentration factors and biochemical parameters, related with clam's metabolic capacity and oxidative stress, were evaluated after 28 days exposure to environmentally relevant scenarios of these stressors. The results showed limited impacts of the drugs (single and combined) at control and warming condition. Indeed, it appeared that warming improved the oxidative status of contaminated clams (higher reduced to oxidized glutathione ratio, lower lipid peroxidation and protein carbonylation levels), especially when both drugs were combined. This may result from clam's defence mechanisms activation and reduced metabolic capacity that, respectively, increased elimination and limited production of reactive oxygen species. At low stress levels, defence mechanisms were not activated which resulted into oxidative stress. The present findings highlighted that under higher stress levels clams may be able to activate defence strategies that were sufficient to avoid cellular damages and loss of redox homeostasis. Nevertheless, low concentrations were tested in the present study and the observed responses may greatly change under increased pollution levels or temperatures. Further research on this topic is needed since marine heat waves are increasing in frequency and intensity and pollution levels of some pharmaceuticals are also increasing in coastal systems.

Highly used antibiotics, such as amoxicillin (AMX), are frequently detected in the aquatic environment due to contaminated effluent disposal, alerting for the possible induction of antimicrobial resistance. In this study, the photodegradation of AMX under simulated solar radiation and environmental influencing factors affecting this process (pH, salinity, and presence of humic substances or reactive oxygen species scavengers) were evaluated to further understand its persistency in the aquatic environment. Photodegradation of AMX was shown to be faster at higher pH (t1/2 = 21.0 ± 0.6 h at pH 8.0; t1/2 = 8.0 ± 0.3 h at pH 9.0). On the other hand, photolysis was slower (t1/2 = 25.1 ± 0.7 h) for high salinity (NaCl). Through the use of •OH and 1O2 scavengers (propan-2-ol (20 mmol L−1) and sodium azide (5 mmol L−1), respectively), it was concluded that the main pathway for AMX photodegradation in phosphate buffer solution (PBS) is indirect photolysis via •OH. Freshwater and brackish water were also studied to evaluate matrix effects on the photodegradation, which were found to be significantly faster than in PBS (t1/2 = 12.5 ± 0.3 h in freshwater; t1/2 = 3.8 ± 0.3 h in brackish water; t1/2 = 21.0 ± 0.6 h in PBS, pH 8.0).

In coastal systems, pollutants as pharmaceutical drugs exert changes from the molecular to the organism level in marine bivalves. Besides pollutants, coastal systems are prone to changes in environmental parameters, as the alteration of salinity values because of Climate Change. Together, these stressors (pharmaceutical drugs and salinity changes) can exert different threats than each stressor acting individually; for example, salinity can change the physical-chemical properties of the drugs and/or the sensitivity of the organisms to them. However, limited information is available on this subject, with variable results, and for this reason, this study aimed to evaluate the impacts of salinity changes (15, 25 and 35) on the effects of the antiepileptic carbamazepine (CBZ, 1 μg/L) and the antihistamine cetirizine (CTZ, 0.6 μg/L), when acting individually and combined (CBZ + CTZ), in the edible clam Ruditapes philippinarum. After 28 days of exposure, drugs concentrations, bioconcentration factors and biochemical parameters, related to clam's metabolic capacity and oxidative stress were evaluated. The results showed that clams under low salinity suffered more changes in metabolic, antioxidant and biotransformation activities, in comparison with the remaining salinities under study. However, limited impacts were observed when comparing drug effects at low salinity. Indeed, it seemed that CTZ and CBZ + CTZ, under high salinity (salinity 35) were the worst exposure conditions for the clams, since they caused higher levels of cellular damage. It stands out that salinity changes altered the impact of pharmaceutical drugs on marine bivalves.

Abstract This work aims to test the adsorption process for the removal of the fish anaesthetic MS-222 from water using biochars obtained from agricultural biowastes ( Eucalyptus bark, peanut shells, walnut shells, peach stones, grape seeds and olive waste) as adsorbents. An industrial residue (primary paper mill sludge) and a commercial activated carbon were tested for comparison purposes. The starting materials and the resulting biochars were characterized by elemental and proximate analyses, total organic carbon, FTIR, 13 C and 1 H solid state NMR, and SEM. Also, specific surface area and porosity of biochars were determined. Then, batch kinetic and equilibrium experiments were performed on the adsorption of MS-222 onto the different produced biochars. The fastest kinetic was obtained using primary sludge pyrolysed (30 min to equilibrium attainment) and the highest biochars adsorption capacity was obtained using peanut shells (34 mg g −1 of maximum adsorption capacity, predicted by the Langmuir–Freundlich model). Commercial activated carbon reaches 349 mg g −1 of maximum adsorption capacity, as predicted by Langmuir model.