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A comparison of statistical methods for deriving freshwater quality criteria for the protection of aquatic organisms Full text
2014
Xing, Liqun | Liu, Hongling | Zhang, Xiaowei | Hecker, Markus | Giesy, John P. | Yu, Hongxia
Species sensitivity distributions (SSDs) are increasingly used in both ecological risk assessment and derivation of water quality criteria. However, there has been debate about the choice of an appropriate approach for derivation of water quality criteria based on SSDs because the various methods can generate different values. The objective of this study was to compare the differences among various methods. Data sets of acute toxicities of 12 substances to aquatic organisms, representing a range of classes with different modes of action, were studied. Nine typical statistical approaches, including parametric and nonparametric methods, were used to construct SSDs for 12 chemicals. Water quality criteria, expressed as hazardous concentration for 5 % of species (HC₅), were derived by use of several approaches. All approaches produced comparable results, and the data generated by the different approaches were significantly correlated. Variability among estimates of HC₅of all inclusive species decreased with increasing sample size, and variability was similar among the statistical methods applied. Of the statistical methods selected, the bootstrap method represented the best-fitting model for all chemicals, while log-triangle and Weibull were the best models among the parametric methods evaluated. The bootstrap method was the primary choice to derive water quality criteria when data points are sufficient (more than 20). If the available data are few, all other methods should be constructed, and that which best describes the distribution of the data was selected.
Show more [+] Less [-]Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals Full text
2014
Wehrer, Markus | Lissner, Heidi | Bloem, Esther | French, Helen | Totsche, Kai Uwe
Non-invasive spatially resolved monitoring techniques may hold the key to observe heterogeneous flow and transport behavior of contaminants in soils. In this study, time-lapse electrical resistivity tomography (ERT) was employed during an infiltration experiment with deicing chemical in a small field lysimeter. Deicing chemicals like potassium formate, which frequently impact soils on airport sites, were infiltrated during snow melt. Chemical composition of seepage water and the electrical response was recorded over the spring period 2010. Time-lapse electrical resistivity tomographs are able to show the infiltration of the melt water loaded with ionic constituents of deicing chemicals and their degradation product hydrogen carbonate. The tomographs indicate early breakthrough behavior in parts of the profile. Groundtruthing with pore fluid conductivity and water content variations shows disagreement between expected and observed bulk conductivity. This was attributed to the different sampling volume of traditional methods and ERT due to a considerable fraction of immobile water in the soil. The results show that ERT can be used as a soil monitoring tool on airport sites if assisted by common soil monitoring techniques.
Show more [+] Less [-]Hexadecane and pristane degradation potential at the level of the aquifer—evidence from sediment incubations compared to in situ microcosms Full text
2014
Schurig, Christian | Miltner, Anja | Kaestner, Matthias
Monitored natural attenuation is widely accepted as a sustainable remediation method. However, methods providing proof of proceeding natural attenuation within the water-unsaturated (vadose) zone are still relying on proxies such as measurements of reactive and non-reactive gases, or sediment sampling and subsequent mineralisation assays, under artificial conditions in the laboratory. In particular, at field sites contaminated with hydrophobic compounds, e.g. crude oil spills, an in situ evaluation of natural attenuation is needed, because in situ methods are assumed to provide less bias than investigations applying either proxies for biodegradation or off-site microcosm experiments. In order to compare the current toolbox of methods with the recently developed in situ microcosms, incubations with direct push-sampled sediments from the vadose and the aquifer zones of a site contaminated with crude oil were carried out in conventional microcosms and in situ microcosms. The results demonstrate the applicability of the in situ microcosm approach also outside water-saturated aquifer conditions in the vadose zone. The sediment incubation experiments demonstrated turnover rates in a similar range (vadose, 4.7 mg/kg*day; aquifer, 6.4 mgₕₑₓₐdₑcₐₙₑ/kgₛₒᵢₗ/day) of hexadecane degradation in the vadose zone and the aquifer, although mediated by slightly different microbial communities according to the analysis of fatty acid patterns and amounts. Additional experiments had the task of evaluating the degradation potential for the branched-chain alkane pristane (2,6,10,14-tetramethylpentadecane). Although this compound is regarded to be hardly degradable in comparison to n-alkanes and is thus frequently used as a reference parameter for indexing the extent of biodegradation of crude oils, it could be shown to be degraded by means of the incubation experiments. Thus, the site had a high inherent potential for natural attenuation of crude oils both in the vadose zone and the aquifer.
Show more [+] Less [-]The influence of SBR parameters on the sludge toxicity of synthetic wastewater containing bisphenol A Full text
2014
Chen, Xiurong | Zhao, Jianguo | Zhao, Jun | Yang, Ne | Zhang, Fei | Jiang, Zijian
Synthetic wastewater with bisphenol A (BPA) concentrations of 7.5, 20, and 40 mg/L was treated with activated sludge sequential batch reactors (SBRs). The sludge acute toxicity indicated by the inhibitory ratio to luminous bacteria T3 was evaluated. The influent COD was controlled at approximately 300 mg/L, and aerobic conditions were maintained in the SBR. It was found that the process of BPA biodegradation, as opposed to BPA adsorption, contributed to the formation of sludge toxicity; there was a positive relationship between sludge toxicity and influent BPA concentration, and the toxicity centralized in intracellular regions and the intersection of extracellular polymeric substances (EPS) in sludge flocs. Since the BPA biodegradation process dedicated to sludge toxicity, the influence of key operational parameters such as sludge retention time (SRT) and hydraulic retention time (HRT) on sludge toxicity were investigated. It was founded that sludge toxicity decreased significantly when SRT and HRT were shortened from 20 to 10 days and 12 to 8 h, respectively. The results of Pearson correlation analysis indicated that the Shannon index H of the bacterial community correlated significantly to sludge toxicity. The results from both similarity analysis and UPGMA indicated that influent quality characteristic contributes much more to bacterial community than operation parameters, and then leads to difference between blank and control sludge toxicity.
Show more [+] Less [-]Detection of feral GT73 transgenic oilseed rape (Brassica napus) along railway lines on entry routes to oilseed factories in Switzerland Full text
2014
Hecht, Mirco | Oehen, Bernadette | Schulze, Jürg | Brodmann-Kron, Peter | Bagutti, Claudia
To obtain a reference status prior to cultivation of genetically modified oilseed rape (OSR, Brassica napus L.) in Switzerland, the occurrence of feral OSR was monitored along transportation routes and at processing sites. The focus was set on the detection of (transgenic) OSR along railway lines from the Swiss borders with Italy and France to the respective oilseed processing factories in Southern and Northern Switzerland (Ticino and region of Basel). A monitoring concept was developed to identify sites of largest risk of escape of genetically modified plants into the environment in Switzerland. Transport spillage of OSR seeds from railway goods cars particularly at risk hot spots such as switch yards and (un)loading points but also incidental and continuous spillage were considered. All OSR plants, including their hybridization partners which were collected at the respective monitoring sites were analyzed for the presence of transgenes by real-time PCR. On sampling lengths each of 4.2 and 5.7 km, respectively, 461 and 1,574 plants were sampled in Ticino and the region of Basel. OSR plants were found most frequently along the routes to the oilseed facilities, and in larger amounts on risk hot spots compared to sites of random sampling. At three locations in both monitored regions, transgenic B. napus line GT73 carrying the glyphosate resistance transgenes gox and CP4 epsps were detected (Ticino, 22 plants; in the region of Basel, 159).
Show more [+] Less [-]Impact of wastewater treatment plants on receiving surface waters and a tentative risk evaluation: the case of estrogens and beta blockers Full text
2014
Gabet-Giraud, V. | Miège, C. | Jacquet, R. | Coquery, M.
Impact of wastewater treatment plants on receiving surface waters and a tentative risk evaluation: the case of estrogens and beta blockers Full text
2014
Gabet-Giraud, V. | Miège, C. | Jacquet, R. | Coquery, M.
Five estrogenic hormones (unconjugated + conjugated fractions) and 10 beta blockers were analyzed in three wastewater treatment plant (WWTP) effluents and receiving river waters in the area of Lyon, France. In the different samples, only two estrogens were quantified: estrone and estriol. Some beta blockers, such as atenolol, acebutolol, and sotalol, were almost always quantified, but others, e.g., betaxolol, nadolol, and oxprenolol were rarely quantified. Concentrations measured in river waters were in the nanogram per liter range for estrogens and between 0.3 and 210 ng/L for beta blockers depending on the substance and the distance from the WWTP outfall. The impact of the WWTP on the receiving rivers was studied and showed a clear increase in concentrations near the WWTP outfall. For estrogens, the persistence in surface waters was not evaluated given the low concentrations levels (around 1 ng/L). For beta blockers, concentrations measured downstream of the WWTP outfall were up to 16 times higher than those measured upstream. Also, the persistence of metoprolol, nadolol, and propranolol was noted even 2 km downstream of the WWTP outfall. The comparison of beta blocker fingerprints in the samples collected in effluent and in the river also showed the impact of WWTP outfall on surface waters. Finally, a tentative environmental risk evaluation was performed on 15 sites by calculating the ratio of receiving water concentrations to predicted non-effect concentrations (PNEC). For estrogens, a total PNEC of 5 ng/L was considered and these substances were not linked to any potential environmental risk (only one site showed an environmental risk ratio above 1). Unfortunately, few PNECs are available and risk evaluation was only possible for 4 of the 10 beta blockers studied: acebutolol, atenolol, metoprolol, and propranolol. Only propranolol presented a ratio near or above 1, showing a possible environmental risk for 4 receiving waters out of 15.
Show more [+] Less [-]Impact of wastewater treatment plants on receiving surface waters and a tentative risk evaluation: the case of estrogens and beta blockers Full text
2014
Gabet Giraud, V. | Miege, Cecile | Jacquet, R. | Coquery, Marina | Milieux aquatiques, écologie et pollutions (UR MALY) ; Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA [TR2_IRSTEA]TED | Five estrogenic hormones (unconjugated+conjugated fractions) and 10 beta blockers were analyzed in three wastewater treatment plant (WWTP) effluents and receiving river waters in the area of Lyon, France. In the different samples, only two estrogens were quantified: estrone and estriol. Some beta blockers, such as atenolol, acebutolol, and sotalol, were almost always quantified, but others, e.g., betaxolol, nadolol, and oxprenolol were rarely quantified. Concentrations measured in river waters were in the nanogram per liter range for estrogens and between 0.3 and 210 ng/L for beta blockers depending on the substance and the distance from theWWTP outfall. The impact of the WWTP on the receiving rivers was studied and showed a clear increase in concentrations near the WWTP outfall. For estrogens, the persistence in surface waters was not evaluated given the low concentrations levels (around 1 ng/L). For beta blockers, concentrations measured downstream of the WWTP outfall were up to 16 times higher than those measured upstream. Also, the persistence of metoprolol, nadolol, and propranolol was noted even 2 km downstream of the WWTP outfall. The comparison of beta blocker fingerprints in the samples collected in effluent and in the river also showed the impact of WWTP outfall on surface waters. Finally, a tentative environmental risk evaluation was performed on 15 sites by calculating the ratio of receiving water concentrations to predicted non-effect concentrations (PNEC). For estrogens, a total PNEC of 5 ng/L was considered and these substances were not linked to any potential environmental risk (only one site showed an environmental risk ratio above 1). Unfortunately, few PNECs are available and risk evaluation was only possible for 4 of the 10 beta blockers studied: acebutolol, atenolol, metoprolol, and propranolol. Only propranolol presented a ratio near or above 1, showing a possible environmental risk for 4 receiving waters out of 15.
Show more [+] Less [-]Brown rust disease control in winter wheat: I. Exploring an approach for disease progression based on night weather conditions Full text
2014
El Jarroudi, Moussa | Kouadio, Louis | Delfosse, Philippe | Tychon, Bernard
Brown rust disease control in winter wheat: I. Exploring an approach for disease progression based on night weather conditions Full text
2014
El Jarroudi, Moussa | Kouadio, Louis | Delfosse, Philippe | Tychon, Bernard
An empirical approach for simulating the infection and progress of leaf rust (caused by Puccinia triticina) during stem elongation on winter wheat was analysed for the 2000 to 2006 growing seasons. The approach was elaborated based on night weather conditions (i.e., air temperature, relative humidity and rainfall) and leaf rust occurrences. Data from three consecutive cropping seasons (2000–2002) at four representative sites of the Grand-Duchy of Luxembourg were used in the set-up phase. The capability to correctly simulate the occurrence expression of P. triticina infections on the upper leaf layers was then assessed over the 2003–2006 period. Our study revealed that the development of leaf rust required a period of at least 12 consecutive hours with air temperatures ranging between 8 and 16 °C, a relative humidity greater than 60 % (optimal values being 12–16 °C and up to 80 % for air temperatures and relative humidity, respectively) and rainfall less than 1 mm. Moreover, leaf rust occurrences and infections were satisfactorily simulated. The false alarm ratio was ranged from 0.06 to 0.20 in all the study sites. The probability of detection and critical success index for WLR infection were also close to 1 (perfect score).
Show more [+] Less [-]Brown rust disease control in winter wheat: I. Exploring an approach for disease progression based on night weather conditions Full text
2014
El Jarroudi, Moussa | Centre de recherche Public Gabriel Lipmann, Luxembourg
peer reviewed | An empirical approach for simulating the infection and progress of leaf rust (caused by Puccinia triticina) during stem elongation on winter wheat was analysed for the 2000 to 2006 growing seasons. The approach was elaborated based on night weather conditions (i.e., air temperature, relative humidity and rainfall) and leaf rust occurrences. Data from three consecutive cropping seasons (2000-2002) at four representative sites of the Grand-Duchy of Luxembourg were used in the set-up phase. The capability to correctly simulate the occurrence expression of P. triticina infections on the upper leaf layers was then assessed over the 2003-2006 period. Our study revealed that the development of leaf rust required a period of at least 12 consecutive hours with air temperatures ranging between 8 and 16 °C, a relative humidity greater than 60 % (optimal values being 12-16 °C and up to 80 % for air temperatures and relative humidity, respectively) and rainfall less than 1 mm. Moreover, leaf rust occurrences and infections were satisfactorily simulated. The false alarm ratio was ranged from 0.06 to 0.20 in all the study sites. The probability of detection and critical success index for WLR infection were also close to 1 (perfect score). | Sentinelle
Show more [+] Less [-]Decontamination of polycyclic aromatic hydrocarbons and nonylphenol from sewage sludge using hydroxypropyl-β-cyclodextrin and evaluation of the toxicity of leachates Full text
2014
Sánchez-Trujillo, Maria Antonia | Lacorte, Silvia | Villaverde, Jaime | Barata, Carlos | Morillo, Esmeralda
Decontamination of polycyclic aromatic hydrocarbons and nonylphenol from sewage sludge using hydroxypropyl-β-cyclodextrin and evaluation of the toxicity of leachates Full text
2014
Sánchez-Trujillo, Maria Antonia | Lacorte, Silvia | Villaverde, Jaime | Barata, Carlos | Morillo, Esmeralda
A decontamination technique based in cyclodextrin extraction has been developed to eliminate nonylphenol (NP) and 16 polycyclic aromatic hydrocarbons (PAHs; the US Environmental Protection Agency priority pollutants list) from sewage sludge. In a first step, PAHs and NP were characterised in six sludges to determine contamination levels according to limit values proposed by the European Union Sludge Directive draft. There were few variations in the total PAHs content with levels of 1.88 to 3.05 mg kg⁻¹. Three-ring PAHs predominated, but fluoranthene and pyrene were also present. None of the sludge exceeded the PAHs limit proposed by the European Union’s draft Directive. On the contrary, NP content in four of the six sludges was over the recommended limits of 50 mg kg⁻¹for NP ethoxylates. With the aim of obtaining NP values below the concentration limits proposed to use the sewage sludge as agricultural amendments, a preliminary study using hydroxypropyl-β-cyclodextrin (HPBCD) extractions as a decontamination technique was carried out. About 90 % of NP content was removed with only one extraction with HPBCD, whereas after three sequential extractions using an aqueous solution without HPBCD, the NP extraction percentage was less than 1 %. Simultaneously, PAHs extraction percentages obtained with HPBCD were also much higher than when aqueous solution was used, especially in the case of two- and three-ring PAHs. Finally, the potential environmental hazard of HPBCD leachates to aquatic organisms (Daphnia magna) was tested. These results indicate that the treatment of sewage sludge with cyclodextrin could allow their safe use as fertiliser in agriculture.
Show more [+] Less [-]Decontamination of polycyclic aromatic hydrocarbons and nonylphenol from sewage sludge using hydroxypropyl-β-cyclodextrin and evaluation of the toxicity of leachates Full text
2014
Sánchez Trujillo, Mª Antonia | Lacorte Bruguera, Silvia | Villaverde Capellán, J. | Barata Martí, Carlos | Morillo González, Esmeralda
11 páginas.-- 2 tablas.-- 3 figuras.-- 61 referencias | A decontamination technique based in cyclodextrin extraction has been developed to eliminate nonylphenol (NP) and 16 polycyclic aromatic hydrocarbons (PAHs; the US Environmental Protection Agency priority pollutants list) from sewage sludge. In a first step, PAHs and NP were characterised in six sludges to determine contamination levels according to limit values proposed by the European Union Sludge Directive draft. There were few variations in the total PAHs content with levels of 1.88 to 3.05 mg kg-1. Three-ring PAHs predominated, but fluoranthene and pyrene were also present. None of the sludge exceeded the PAHs limit proposed by the European Union's draft Directive. On the contrary, NP content in four of the six sludges was over the recommended limits of 50 mg kg-1 for NP ethoxylates. With the aim of obtaining NP values below the concentration limits proposed to use the sewage sludge as agricultural amendments, a preliminary study using hydroxypropyl-β-cyclodextrin (HPBCD) extractions as a decontamination technique was carried out. About 90 % of NP content was removed with only one extraction with HPBCD, whereas after three sequential extractions using an aqueous solution without HPBCD, the NP extraction percentage was less than 1 %. Simultaneously, PAHs extraction percentages obtained with HPBCD were also much higher than when aqueous solution was used, especially in the case of two- and three-ring PAHs. Finally, the potential environmental hazard of HPBCD leachates to aquatic organisms (Daphnia magna) was tested. These results indicate that the treatment of sewage sludge with cyclodextrin could allow their safe use as fertiliser in agriculture. © 2013 Springer-Verlag Berlin Heidelberg. | Support from projects CTM2006-04626 and CTM2009-07335, Spanish Ministry of Science and Innovation (cofunded by Fondo Europeo de Desarrollo Regional, FEDER), are greatly appreciated. M.A. Sánchez-Trujillo acknowledges a research contract from Consejo Superior de Investigaciones Científicas (CSIC, JAEPre 0800763) cofinanced by Fondo Social Europeo (FSE). | Peer Reviewed
Show more [+] Less [-]Acid–base physiology response to ocean acidification of two ecologically and economically important holothuroids from contrasting habitats, Holothuria scabra and Holothuria parva Full text
2014
Collard, Marie | Eeckhaut, Igor | Dehairs, Frank | Dubois, Philippe
Acid–base physiology response to ocean acidification of two ecologically and economically important holothuroids from contrasting habitats, Holothuria scabra and Holothuria parva Full text
2014
Collard, Marie | Eeckhaut, Igor | Dehairs, Frank | Dubois, Philippe
Sea cucumbers are dominant invertebrates in several ecosystems such as coral reefs, seagrass meadows and mangroves. As bioturbators, they have an important ecological role in making available calcium carbonate and nutrients to the rest of the community. However, due to their commercial value, they face overexploitation in the natural environment. On top of that, occurring ocean acidification could impact these organisms, considered sensitive as echinoderms are osmoconformers, high-magnesium calcite producers and have a low metabolism. As a first investigation of the impact of ocean acidification on sea cucumbers, we tested the impact of short-term (6 to 12 days) exposure to ocean acidification (seawater pH 7.7 and 7.4) on two sea cucumbers collected in SW Madagascar, Holothuria scabra, a high commercial value species living in the seagrass meadows, and H. parva, inhabiting the mangroves. The former lives in a habitat with moderate fluctuations of seawater chemistry (driven by day–night differences) while the second lives in a highly variable intertidal environment. In both species, pH of the coelomic fluid was significantly negatively affected by reduced seawater pH, with a pronounced extracellular acidosis in individuals maintained at pH 7.7 and 7.4. This acidosis was due to an increased dissolved inorganic carbon content and pCO₂of the coelomic fluid, indicating a limited diffusion of the CO₂towards the external medium. However, respiration and ammonium excretion rates were not affected. No evidence of accumulation of bicarbonate was observed to buffer the coelomic fluid pH. If this acidosis stays uncompensated for when facing long-term exposure, other processes could be affected in both species, eventually leading to impacts on their ecological role.
Show more [+] Less [-]Acid-base physiology response to ocean acidification of two ecologically and economically important holothuroids from contrasting habitats, Holothuria scabra and Holothuria parva Full text
2014
Collard, Marie | Eeckhaut, Igor | Dehairs, Frank | Dubois, Philippe
Sea cucumbers are dominant invertebrates in several ecosystems such as coral reefs, seagrass meadows and mangroves. As bioturbators, they have an important ecological role in making available calcium carbonate and nutrients to the rest of the community. However, due to their commercial value, they face overexploitation in the natural environment. On top of that, occurring ocean acidification could impact these organisms, considered sensitive as echinoderms are osmoconformers, high-magnesium calcite producers and have a low metabolism. As a first investigation of the impact of ocean acidification on sea cucumbers, we tested the impact of short-term (6 to 12 days) exposure to ocean acidification (seawater pH 7.7 and 7.4) on two sea cucumbers collected in SW Madagascar, Holothuria scabra, a high commercial value species living in the seagrass meadows, and H. parva, inhabiting the mangroves. The former lives in a habitat with moderate fluctuations of seawater chemistry (driven by day-night differences) while the second lives in a highly variable intertidal environment. In both species, pH of the coelomic fluid was significantly negatively affected by reduced seawater pH, with a pronounced extracellular acidosis in individuals maintained at pH 7.7 and 7.4. This acidosis was due to an increased dissolved inorganic carbon content and pCO2 of the coelomic fluid, indicating a limited diffusion of the CO2 towards the external medium. However, respiration and ammonium excretion rates were not affected. No evidence of accumulation of bicarbonate was observed to buffer the coelomic fluid pH. If this acidosis stays uncompensated for when facing long-term exposure, other processes could be affected in both species, eventually leading to impacts on their ecological role.
Show more [+] Less [-]Biochemical and standard toxic effects of acetaminophen on the macrophyte species Lemna minor and Lemna gibba Full text
2014
Nunes, Bruno | Pinto, Glória | Martins, Liliana | Gonçalves, Fernando | Antunes, Sara C.
Biochemical and standard toxic effects of acetaminophen on the macrophyte species Lemna minor and Lemna gibba Full text
2014
Nunes, Bruno | Pinto, Glória | Martins, Liliana | Gonçalves, Fernando | Antunes, Sara C.
Acetaminophen is globally one of the most prescribed drugs due to its antipyretic and analgesic properties. However, it is highly toxic when the dosage surpasses the detoxification capability of an exposed organism, with involvement of an already described oxidative stress pathway. To address the issue of the ecotoxicity of acetaminophen, we performed acute exposures of two aquatic plant species, Lemna gibba and Lemna minor, to this compound. The selected biomarkers were number of fronds, biomass, chlorophyll content, lipid peroxidation (TBARS assay), and proline content. Our results showed marked differences between the two species. Acetaminophen caused a significant decrease in the number of fronds (EC₅₀ = 446.6 mg/L), and the establishment of a dose-dependent peroxidative damage in L. minor, but not in L. gibba. No effects were reported in both species for the indicative parameters chlorophyll content and total biomass. However, the proline content in L. gibba was substantially reduced. The overall conclusions point to the occurrence of an oxidative stress scenario more prominent for L. minor. However, the mechanisms that allowed L. gibba to cope with acetaminophen exposure were distinct from those reported for L. minor, with the likely involvement of proline as antioxidant.
Show more [+] Less [-]Biochemical and standard toxic effects of acetaminophen on the macrophyte species Lemna minor and Lemna gibba Full text
1000
Nunes, Bruno | Pinto, Glória | Martins, Liliana | Gonçalves, Fernando | Antunes, Sara C.
Acetaminophen is globally one of the most prescribed drugs due to its antipyretic and analgesic properties. However, it is highly toxic when the dosage surpasses the detoxification capability of an exposed organism, with involvement of an already described oxidative stress pathway. To address the issue of the ecotoxicity of acetaminophen, we performed acute exposures of two aquatic plant species, Lemna gibba and Lemna minor, to this compound. The selected biomarkers were number of fronds, biomass, chlorophyll content, lipid peroxidation (TBARS assay), and proline content. Our results showed marked differences between the two species. Acetaminophen caused a significant decrease in the number of fronds (EC50 = 446.6 mg/L), and the establishment of a dose-dependent peroxidative damage in L. minor, but not in L. gibba. No effects were reported in both species for the indicative parameters chlorophyll content and total biomass. However, the proline content in L. gibba was substantially reduced. The overall conclusions point to the occurrence of an oxidative stress scenario more prominent for L. minor. However, the mechanisms that allowed L. gibba to cope with acetaminophen exposure were distinct from those reported for L. minor, with the likely involvement of proline as antioxidant.
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