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Antibiotics in the environment represent a substantial pollution threat. Among these emerging pollutants, ionophore anticoccidials are of special concern due to their potential ecological impact, persistence in the environment, and role in promoting antimicrobial resistance. To investigate the adsorption/desorption of the ionophore antibiotic salinomycin (SAL) on/from raw and modified clay adsorbents, batch-type experiments were performed using 0.5 g of clay adsorbent mixed with 10 mL of increasing doses of SAL solutions for each sample, at room temperature, with a contact time of 24 h. All measurements were conducted in triplicate employing HPLC-UV equipment. Three different natural (raw) and modified clay samples were investigated, which were denominated as follows: AM (with 51% calcite), HJ1 (with 32% kaolinite), and HJ2 (with 32% microcline). The experiments were carried out using three pH ranges: between 3.33 and 4.49 for acid-activated clays, 8.39-9.08 for natural clays, and 9.99-10.18 for base-activated clays. The results indicated that, when low concentrations of the antibiotic were added (from 5 to 20 μmol L -1 ), more than 98% of SAL was strongly adsorbed by almost all clays, irrespective of the physicochemical and mineralogical composition of the clays or their pH values. When higher SAL concentrations were added (40 and 100 μmol L -1 ), the adsorption of the antibiotic showed pH-dependent ligand adsorption mechanisms: (i) highly decreased as the pH raised (for the raw and base-activated AM and HJ1 clays), while (ii) slightly decreased as the pH decreased (on the acid-activated clays). Among the adsorption equations tested (Freundlich, Langmuir, and Linear), the Freundlich model was identified as the most suitable for fitting the data corresponding to SAL adsorption onto the studied clays. SAL desorption from clays was consistently below 10% for all the clay samples, especially for the acid-activated clays, due to cation bridging adsorption mechanisms, when the lowest concentration of the antibiotic was added. Additionally, it should be stressed that the desorption values can increase with rising SAL concentrations, but they always remain below 20%. Overall, the clays here investigated (both raw and modified) provide a cost-effective and efficient alternative for the removal of the veterinary anticoccidial antibiotic SAL, with potential positive and practical implications in environmental remediation and antibiotic pollution management, particularly by serving as amendments for contaminated soils to enhance their adsorption capacities against SAL. Additionally, using these clays in water treatment processes could improve the efficiency of mitigating antibiotic contamination in aquatic systems., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Given his role as editor, Dr. Avelino Núñez-Delgado was not involved in the peer-review of this article and has no access to information regarding its peer-review. Full responsibility for the editorial process for this article was delegated to Professor Raf Dewil., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The anticoccidial monensin (MON) is a high-concern emerging pollutant. This research focused on six low-cost bio-adsorbents (alfa, cactus, and palm fibers, and acacia, eucalyptus, and zean oak barks), assessing their potential for MON removal. Batch adsorption/desorption tests were carried out, and the results were fitted to the Freundlich, Langmuir, Linear, Sips, and Temkin models. The concentrations adsorbed by the six materials were very similar when low doses of antibiotic were added, while they differed when adding MON concentrations higher than 20 µmol L -1 (adsorption ranging 256.98-1123.98 μmol kg -1 ). The highest adsorption corresponded to the sorbents with the most acidic pH (<5.5) and the highest organic matter and effective cation exchange capacity values (eucalyptus bark and acacia bark, reaching 92.3% and 87.8%), whereas cactus and palm fibers showed the lowest values (18.3% and 10.17%). MON desorption was below 8.5%, except for cactus and palm fibers. Temkin was the model showing the best adjustment to the experimental data, followed by the Langmuir and the Sips models. The overall results indicate that eucalyptus bark, alfa fiber, and acacia bark are efficient bio-adsorbents with potential for MON removal, retaining it when spread in environmental compartments, reducing related risks for human and environmental health.

Environmental discharge of wastewater represents a source of chemical and biological pollutants. This study firstly evaluates the microbiological and physicochemical quality of treated wastewaters collected from two wastewater treatment plants (WWTPs) located in two different Tunisian cities namely Sidi Bouzid (SB) and Gafsa (G). Then, the capacity of three raw and acid/base-activated local clays to enhance the quality of wastewaters was assessed. The results indicate that the quantities of enteric bacteria (oscillating from 1.381 × 10 3 to 1.4 × 10 8  CFU/100 mL), fungi (between 1.331 × 10 3 and 1.781 × 10 4  CFU/100 mL), as well as SARS-CoV-2 (between 4.25 × 10 3 and 5.05 × 10 5  CFU/100 mL) and Hepatitis A virus RNA (form 4.25 × 10 3 to 7.4 × 10 4  CFU/100 mL) detected in effluent wastewaters were not in compliance with the Tunisian standards for both studied WWTPs. Likewise for other indicators such as electrical conductivity (ranging 4.9-5.4 mS/cm), suspended matter (145-160 g l -1 ), chemical oxygen demand (123-160 mg l -1 ), biological oxygen demand 5 (172-195 mg l -1 ), chloride, Total Kjeldahl nitrogen (TKN) and phosphorus contents (710, 58-66 and 9.47-10.83 mg l -1 respectively), the registered values do not agree with the set standards established for wastewater treatment. On the other hand, the pH values fitted (oscillating from 6.86 (at G) to 7.24 (at SB) with the Tunisian standards for both WWTPs. After treatment, wastewaters showed better values for the microbiological parameters, especially for the clays designed as AM and HJ1, which eliminated 100% of viruses. In addition, when acid-activated AM clays were applied, a marked improvement in the quality of physicochemical parameters was obtained, especially for suspended matter (2 and 4 g l -1 for SB and G, respectively), TKN (5.2 (SB) and 6.40 (G) mg/l), phosphorus (1.01 (SB) and 0.81 (G) mg/l). Our results open perspectives for the possibility of efficiently using these specific clays in the enhancement of the quality of treated wastewaters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The primers HAV2 and HAV3 differed by a single nucleotide, representing a deletion carried by some HAV strains and were used to amplify 5′ non-coding region (5′ NCR)., (Copyright © 2023. Published by Elsevier Inc.)

The presence of pharmaceuticals in agricultural soils, like amoxicillin (AMX) and ciprofloxacin (CIP), poses a significant environmental challenge with potential implications for ecosystems and human well-being. This study explores the simultaneous adsorption of AMX and CIP on crop soils and bio-adsorbents, focusing on competitive adsorption dynamics. Tests were conducted with varying pharmaceutical concentrations in six soils and three bio-adsorbents. CIP consistently exhibited higher adsorption than AMX, particularly at higher concentrations. In the binary system, AMX's adsorption exceeded the individual system at higher concentrations, implying a synergistic effect. Bio-adsorbents, especially pine bark and oak ash, displayed superior adsorption capacities compared to soils. Some soils exhibited enhanced adsorption and retention of both antibiotics simultaneously, aligning with the cooperative adsorption model. Freundlich's adsorption model described the competitive adsorption systems well. These findings have implications for addressing antibiotic contamination in agricultural ecosystems, offering insights into complex interactions in soil environments amid rising pharmaceutical concerns., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Antibiotic consumption at high levels in both human and veterinary populations pose a risk to their eventual entry into the food chain and/or water bodies, which will adversely affect the health of living organisms. In this work, three materials from forestry and agro-food industries (pine bark, oak ash and mussel shell) were investigated as regards their potential use as bio-adsorbents in the retention of the antibiotics amoxicillin (AMX), ciprofloxacin (CIP) and trimethoprim (TMP). Batch adsorption/desorption tests were conducted, adding increasing concentrations of the pharmaceuticals individually (from 25 to 600 μmol L -1 ), reaching maximum adsorption capacities of ≈ 12000 μmol kg -1 for the three antibiotics, with removal percentages of ≈ 100% for CIP, 98-99% adsorption for TMP onto pine bark, and 98-100% adsorption for AMX onto oak ash. The presence of high calcium contents and alkaline conditions in the ash favored the formation of cationic bridges with AMX, whereas the predominance of hydrogen bonds between pine bark and TMP and CIP functional groups explain the strong affinity and retention of these antibiotics. The Freundlich's model provided the best prediction for AMX adsorption onto oak ash and mussel shell (heterogeneous adsorption), whereas the Langmuir's model described well AMX adsorption onto pine bark, as well as CIP adsorption onto oak ash (homogeneous and monolayer adsorption), while all three models provided satisfactory results for TMP. In the present study, the results obtained were crucial in terms of valorization of these adsorbents and their subsequent use to improve the retention of antibiotics of emerging concern in soils, thereby preventing contamination of waters and preserving environment quality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

In view of the environmental issues caused by antibiotics, this research studies competitive adsorption/desorption for tetracycline (TC) and sulfadiazine (SDZ) in agricultural soils. Competitive adsorption was studied in binary systems (adding equal concentrations of both antibiotics). In addition, it was compared with results from simple systems. In all cases, batch-type adsorption/desorption experiments were carried out. In the binary systems, for the highest antibiotic concentration added, adsorption percentages were always higher for TC (close to 100%) than for SDZ (10-90%). In these systems, TC desorption was lower than 5% for all soils, and generally <10% for SDZ. Comparing TC and SDZ adsorption for the different systems, SDZ was clearly affected by the presence of TC, with SDZ adsorption percentages being was much higher (with differences generally above 65%) in the binary than in the simple systems. On the contrary, comparing the results of TC adsorption in simple and binary systems, TC was not affected by the presence of SDZ, obtaining similar adsorption percentages in both systems. K d and K F values (in the Linear and Freundlich models), were higher in the simple systems in the case of TC, which could be due to competition with SDZ, while for SDZ K d and K F were higher in the binary systems, with a synergistic effect of TC favoring SDZ adsorption. Regarding desorption, it reached 100% for SDZ in some soils in simple systems, dropping to 10% in the presence of TC. TC desorption was <4%, not affected by SDZ. The results indicate that environmental risks would be higher for SDZ, showing differences when both antibiotics are present. This can be considered relevant as regards public health and environmental preservation, in view of direct toxicities and the promotion of resistance to antibiotics associated with the presence of these contaminants in the environment., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Sewage sludge as agricultural amendment is the main route of human-medicine antibiotics to enter soils. When reaching environmental compartments, these compounds can cause significant risks to human and ecological health. Specifically, the antibiotic amoxicillin (AMX) is highly used in medicine, and the fact that more than 80% of the total ingested is excreted increases the chances of causing serious environmental and public health problems. As the use of low-cost bio-adsorbents could help to solve these issues, this research focuses on the retention of AMX onto four by-products of the forestry industry (eucalyptus leaf, pine bark, pine needles, and wood ash) and one from food industry (mussel shell). To carry out this study, batch-type tests were performed, where increasing concentrations of the antibiotic (0, 2.5, 5, 10, 20, 30, 40 and 50 μmol L -1 ) were added to samples of 0.5 g of each bio-adsorbent. Eucalyptus leaf, pine needle and wood ash showed adsorption scores higher than 80%, while it was up to 39% and 48% for pine bark and mussel shell, respectively. For pine bark, wood ash and mussel shell, adsorption data showed good adjustment to the Freundlich and Linear models, while pine needles and eucalyptus leaf did not fit to any model. There was not desorption when the maximum concentration of AMX (50 μmol L -1 ) was added. Overall, eucalyptus leaf, pine needles and wood ash can be considered good bio-adsorbents with high potential to retain AMX, which has significant implications regarding their eventual use to reduce risks of environmental pollution by this antibiotic., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

This research is concerned with the adsorption and desorption of Cu and As(V) on/from different soils and by-products. Both contaminants may reach soils by the spreading of manure/slurries, wastewater, sewage sludge, or pesticides, and also due to pollution caused by mining and industrial activities. Different crop soils were sampled in A Limia (AL) and Sarria (S) (Galicia, NW Spain). Three low-cost by-products were selected to evaluate their bio-adsorbent potential: pine bark, oak ash, and mussel shell. The adsorption/desorption studies were carried out by means of batch-type experiments, adding increasing and individual concentrations of Cu and As(V). The fit of the adsorption data to the Langmuir, Freundlich, and Temkin models was assessed, with good results in some cases, but with high estimation errors in others. Cu retention was higher in soils with high organic matter and/or pH, reaching almost 100%, while the desorption was less than 15%. The As(V) adsorption percentage clearly decreased for higher As doses, especially in S soils, from 60−100% to 10−40%. The As(V) desorption was closely related to soil acidity, being higher for soils with higher pH values (S soils), in which up to 66% of the As(V) previously adsorbed can be desorbed. The three by-products showed high Cu adsorption, especially oak ash, which adsorbed all the Cu added in a rather irreversible manner. Oak ash also adsorbed a high amount of As(V) (>80%) in a rather non-reversible way, while mussel shell adsorbed between 7 and 33% of the added As(V), and pine bark adsorbed less than 12%, with both by-products reaching 35% desorption. Based on the adsorption and desorption data, oak ash performed as an excellent adsorbent for both Cu and As(V), a fact favored by its high pH and the presence of non-crystalline minerals and different oxides and carbonates. Overall, the results of this research can be relevant when designing strategies to prevent Cu and As(V) pollution affecting soils, waterbodies, and plants, and therefore have repercussions on public health and the environment.

The fate of antibiotics reaching soils is a matter of concern, given its potential repercussions on public health and the environment. In this work, the potential bio-reduction of the antibiotic amoxicillin (AMX), affected by sorption and desorption, is studied for 17 soils with clearly different characteristics. To carry out these studies, batch-type tests were performed, adding increasing concentrations of AMX (0, 2.5, 5, 10, 20, 30, 40, and 50 μmol L -1 ) to the soils. For the highest concentration added (50 μmol L -1 ), the adsorption values for forest soils ranged from 90.97 to 102.54 μmol kg -1 (74.21-82.41% of the amounts of antibiotic added), while the range was 69.96-94.87 μmol kg -1 (68.31-92.56%) for maize soils, and 52.72-85.40 μmol kg -1 (50.96-82.55%) for vineyard soils. When comparing the results for all soils, the highest adsorption corresponded to those more acidic and with high organic matter and non-crystalline minerals contents. The best adjustment to adsorption models corresponded to Freundlich's. AMX desorption was generally <10%; specifically, the maximum was 6.5% in forest soils, and 16.9% in agricultural soils. These results can be considered relevant since they cover agricultural and forest soils with a wide range of pH and organic matter contents, for an antibiotic that, reaching the environment as a contaminant, can pose a potential danger to human and environmental health., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

The antibiotic amoxicillin (AMX) may reach soils and other environmental compartments as a pollutant, with potential to affect human and environmental health. To solve/minimize these hazards, it would be clearly interesting to develop effective and low-cost methods allowing the retention/removal of this compound. With these aspects in mind, this work focuses on studying the adsorption/desorption of AMX in different agricultural soils, with and without the amendment of three bio-adsorbents, specifically, pine bark, wood ash and mussel shell. For performing the research, batch-type experiments were carried out, adding increasing concentrations of the antibiotic to soil samples with and without the amendment of these three bio-adsorbents. The results showed that the amendments increased AMX adsorption, with pine bark being the most effective. Among the adsorption models that were tested, the Freundlich equation was the one showing the best fit to the empirical adsorption results. Regarding the desorption values, there was a decrease affecting the soils to which the bio-adsorbents were added, with overall desorption not exceeding 6% in any case. In general, the results indicate that the bio-adsorbents under study contributed to retaining AMX in the soils in which they were applied, and therefore reduced the risk of contamination by this antibiotic, which can be considered useful and relevant to protect environmental quality and public health.

The first aim of this study was to synthesize and characterize reed-based-beads (BBR), an enhanced adsorbent from Tunisian reed. The second purpose was to evaluate and optimize the BBR efficiency for the simultaneous removal of oxytetracycline (OTC) and cadmium (Cd(II)), using central composite design under response surface methodology. The third goal was to elucidate the biosorption mechanisms taking place. It was shown that under optimum conditions (4.19 g L -1 of BBR, 165.54 μmol L -1 of OTC, 362.16 μmol L -1 of Cd(II), pH of 6, and 25.14-h contact time) the highest adsorption percentages (63.66% for OTC and 99.99% for Cd(II)) were obtained. It was revealed that OTC adsorption mechanism was better described by Brouers-Sotolongo fractal equation, with regression coefficient (R 2 ) of 0.99876, and a Person's chi-square (χ 2 ) of 0.01132. The Weibull kinetic equation better explained Cd(II) biosorption (R 2 = 0.99959 and χ 2 = 0.00194). FTIR and isotherm studies confirmed that the BBR surface was heterogeneous, and that adsorption mechanisms were better described by the Freundlich/Jovanovich equation (R 2 = 0.99276 and χ 2 = 0.04864) for OTC adsorption, and by the Brouers-Sotolongo model (R 2 = 0.9851 and χ 2 = 0.77547) for Cd(II) biosorption. Overall results indicate that, at last, the BBR lignocellulosic biocomposite beads could be considered as cost-effective and efficient adsorbent, which could be of socioeconomic and environmental relevance. Graphical abstract., (© 2020. Springer-Verlag GmbH Germany, part of Springer Nature.)

In the context of the current COVID-19 pandemic, and mostly taking a broad perspective, it is clearly relevant to study environmental factors that could affect eventual future outbreaks due to coronaviruses and/or other pathogenic microorganisms. In view of that, the authors of this manuscript review the situation of SARS-CoV-2 and other main pathogenic microorganisms in the environment, focusing on Galicia and Spain. Overall, in addition to showing local data, it is put in evidence that, summed to all efforts being carried out to treat/control this and any other eventual future epidemic diseases, both at local and global levels, a deep attention should be paid to ecological/environmental aspects that have effects on the planet, its ecosystems and their relations/associations with the probability of spreading of eventual future pandemics., (Copyright © 2021 Elsevier Inc. All rights reserved.)

In this work batch-type experiments were used to study the adsorption of the antibiotics doxycycline (DC), enrofloxacin (ENR), and sulfamethoxypyridazine (SMP) in cultivation soils, before and after the removal of soil organic matter. Organic matter removal by calcination resulted not only in C and N removal, but also in increased soil pH, exchangeable basic cations and surface area values. The results indicate a very different behavior depending on the type of antibiotic, showing the adsorption sequence DC > ENR > SMP. Specifically, DC adsorption was very high in untreated soil samples (with organic matter), and was still high (although decreased) after the removal of soil organic matter. Furthermore, the adsorption behavior of DC was clearly dependent on the pH of the medium. Regarding ENR, it also showed high adsorption, although to a lesser extent than DC. However, when soil organic matter was removed, ENR adsorption significantly decreased in all soil samples. As regards SMP, it was adsorbed to a much lesser extent, and the removal of soil organic matter caused an additional drastic decrease in adsorption, reaching negligible values in some samples. Desorption followed the reverse sequence of adsorption, specifically in the order DC < ENR < SMP. In the case of DC, desorption was negligible, both in samples with and without organic matter, while for ENR and SMP, desorption clearly increased for soil samples where organic matter was removed. These results may be of relevance as regards environmental quality and public health, especially to facilitate a correct use of soils and organic amendments in areas that receive the application of substances containing the investigated antibiotics., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This work focuses on studying the efficacy of three different by-products to adsorb three antibiotics (sulfadiazine, SDZ; sulfamethazine, SMT; sulfachloropyridazine, SCP). These antibiotics can be considered pollutants of the environment when they reach water, as well as in cases where they are spread on soils through irrigation or contained in sewage sludge or livestock manure. In this study, batch-type adsorption/desorption experiments were performed for each of the three sulfonamides, adding 7 different concentrations of the antibiotics, going from 1 to 50 μmol L -1 , and with contact time of 24 h. The results indicate that pine bark is the most efficient bioadsorbent among those studied, as it adsorbs up to 95% of the antibiotics added, while desorption is always less than 11%. However, for "oak ash" and mussel shell the adsorption is always lower than 45 and 15%, respectively, and desorption is high, reaching up to 49% from "oak ash" and up to 81% from mussel shell. Adsorption data showed good fitting to the Linear and Freundlich models, with R 2 values between 0.98 and 1.00 in both cases. K d and K F adsorption parameters showed similar values for the same sorbent materials but were much higher for pine bark than for the other two bioadsorbents. The Freundlich's n parameter showed values in the range 0.81-1.28. The highest K F values (and therefore the highest adsorption capacities) were obtained for the antibiotic SCP in pine bark. Pine bark showed the highest capacity to adsorb each of the antibiotics, increasing as a function of the concentration added. When the concentration of sulfonamide added was 50 μM, the amounts adsorbed were 780 μmol kg -1 for SDZ, 890 μmol kg -1 for SMT, and 870 μmol kg -1 for SCP. "Oak ash" and mussel shell have low adsorption capacity for all three sulfonamides, showing values always lower than 150 μmol kg -1 (oak ash) and 20 μmol kg -1 (mussel shell) when a concentration of 50 μmol L -1 of antibiotic is added. The results of this study could aid to make an appropriate management of the by-products studied, in order to facilitate their valorization and recycling in the treatment of environmental compartments polluted with sulfonamide antibiotics., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The increase of concentrations of tetracycline antibiotics in agricultural soils worldwide is of special concern, due to its potential toxic effects on soil bacterial communities. In the present work, the reuse of two waste/by-product materials as soil amendments was tested as a preventive practice for reducing tetracycline antibiotics toxicity in soils. Pine bark (PB), with high percentage of organic carbon, and crushed mussel shell (CMS), a frequent natural liming material, were added to 4 soils in doses 0, 6, 12 and 48 g of by-product per kg -1 of soil (dry weight) of each one (separately). The soils and soil-waste mixtures were then spiked with tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC). After one day of incubation, the bacterial growth was estimated in soils and soil-mixtures using the leucine incorporation technique. The addition of PB to the soils showed two different behaviors, depending on the antibiotics. The toxicity of TC and OTC decreased with the addition of PB (toxicities going from 6 to 25% and from 5 to 36%, respectively). However, CTC toxicity did not change, or even increased in response to the PB amendment. Regarding soil amendment with CMS, it was not effective to prevent the toxicity of any of the three antibiotics studied., (Copyright © 2020. Published by Elsevier Inc.)

Veterinary antibiotics reaching the environment have become a matter of global concern, since they can cause serious negative impacts on human and ecological health. Therefore, a deep understanding of their behavior and fate once they reach the soil environment is of utmost importance to design and implement appropriate measures that could reduce their potential risks. With this aim, batch-type experiments were carried out to study competitive adsorption and desorption for three sulfonamide antibiotics (sulfadiazine -SDZ-, sulfamethazine -SMT-, and sulfachloropyridazine -SCP-) in six crop soils presenting different characteristics. The results obtained showed that sulfonamides have a low retention in soils, with average adsorption percentages of 40% for SDZ, 44% for SMT and 54% for SCP, and with desorption percentages up to 36% for SDZ and SCP and up to 29% for SMT. The retention of sulfonamides was strongly influenced by the soil organic carbon content (SOC), with higher adsorption and less desorption associated to higher SOC contents. In addition, the hydrophobicity of sulfonamides also had an influence, as higher hydrophobicity resulted in higher affinity for soils, showing the affinity sequences: SDZ ~ SMT

Batch-type experiments were used to study competitive adsorption/desorption for the antibiotics tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC), onto by-products from forest and food industries (oak ash, pine bark, and mussel shell). These antibiotics are frequently present in manures and slurries spread on agrosystems. Binary competitive systems were performed by setting the dose of one antibiotic to 200 μmol L -1 , and varying the concentration of a second antibiotic from 50 to 600 μmol L -1 . In the cases where a concentration of 200 μmol L -1 was used for each antibiotic, the results of the binary experiments were also compared with those obtained in parallel tests corresponding to simple and ternary systems using the same concentration. The results indicated that pine bark can adsorb most of the antibiotics added, with desorption being less than 5% in most cases. Oak ash showed high adsorption for all three antibiotics in the simple systems (100% of CTC, 90% of TC, and 80% of OTC), but clearly decreased in the binary systems (up to values below 40%), especially for higher antibiotics concentrations, although desorption was generally less than 5%. Mussel shell showed adsorption results lesser than 25% for OTC and CT in simple systems, while increased up to 65% in binary systems in which CTC was present at high concentrations, but desorption was generally very high. CTC was the antibiotic with the highest adsorption onto all three by-products, and the one showing less decrease for its adsorption in the binary systems. Overall, the smallest differences among the various competitive systems were obtained when the adsorbent used was pine bark, and especially for the CTC antibiotic. These results could aid to develop management practices, based on the use of low-cost bio-sorbents, which would decrease risks of pollution due to tetracycline antibiotics spread in agroecosystems and affecting the environment., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Tetracycline antibiotics (TA) used in veterinary medicine reach terrestrial ecosystems mostly via the repeated applications of animal manures and slurries on agricultural soils, where they may cause toxic effects on bacterial communities. In the current work, we studied the efficacy of adding doses of 0, 6, 24 and 48 g kg -1 of biomass ash (BA) to four different soils to reduce potential negative effects of tetracycline antibiotics. Specifically, soil samples were polluted with different concentrations of tetracycline, oxytetracycline or chlortetracycline, and the bacterial community growth was estimated using the 3 H leucine incorporation technique. Soil amendment with BA increased soil pH (1.3-4.8 units), total carbon (0.7-5.8 g kg -1 ) and Fe and Al oxides concentrations (0.25-3.98 g kg -1 ), as well as bacterial activity (1-9 times compared to the control). In addition, BA amendment at high doses (24 or 48 g kg -1 ) resulted in a similar toxicity decrease for the three antibiotics, but with variations among soils. The reductions in antibiotics toxicity were very variable, ranging between 5% and 100% (total recovery). In view of that, the spreading of BA could be interesting as management practice to reduce risks of soil pollution and subsequent toxicity on bacterial communities due to tetracycline antibiotics., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

With the aim of obtaining information about the environmental fate and dynamics of the antibiotic doxycycline (DC) when it reaches soil, adsorption and desorption processes were studied for this compound in 20 agricultural soils, by means of batch-type and stirred-flow-chamber experiments. The results indicate that the studied soils adsorbed high amounts of DC, with adsorption percentages >91% in all cases. In addition, adsorption results were satisfactorily modeled, with good fittings to the Langmuir and Freundlich equations, with the values for Langmuir's maximum adsorption capacity (q max ) varying between 14,692 and 26,141 μmol kg -1 (average 17,816), and between 1,906 and 13,120 L n μmol 1-n kg -1 (average 6,969) for the Freundlich affinity coefficient, which are very high. The soil variables most related to the adsorption of the antibiotic were linked to organic matter (specifically, soil organic carbon-SOC- and soil nitrogen -N- contents), and to the clay fraction, as well as to cation exchange capacity, being the soils with a greater content in these variables those that presented a greater adsorption. FTIR results shown that DC adsorption mechanisms were based on interactions such as hydrogen bonds and π-π interactions between the antibiotic and soils. Desorption was very low, reaching values between 1 and 2% in batch experiments, and between 5 and 15% in stirred flow chamber experiments, which indicates a strong hysteresis affecting adsorption and desorption processes. This fact can be considered positively, as these soils could retain DC very strongly, thus reducing risks to human and ecological health., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Tetracycline antibiotics spread in the environment constitute a real threat, causing risks that should be controlled. Retention/release of these compounds after interacting with soil components are the main process governing their entry into water bodies, plant uptake, and availability for soil microorganisms. In this work, batch-type experiments were performed to study adsorption/desorption of oxytetracycline (OTC) and chlortetracycline (CTC) in 63 crop soils. The Freundlich model satisfactory described adsorption curves, showing strong affinity of both antibiotics to soils, with adsorption coefficient (K F(ads) ) values between 1015 and 9733 L n μmol 1-n kg -1 for OTC, and between 1099 and 11344 L n μmol 1-n kg -1 for CTC. Desorption percentages were always lower than 10%, indicating that adsorption is highly irreversible. Furthermore, the desorption coefficient (K F(des) ) correlated positive and significantly with K F(ads) , showing that those soils characterized by higher adsorption were also those showing less desorption. Soil organic carbon (SOC) was the soil characteristic that most explained the variance of K F , both for adsorption and desorption, which caused that soils with higher SOC scores showed higher adsorption and lower desorption for both antibiotics. Pedotransfer functions were developed for OTC and CTC, and resulted effective to satisfactory predict K F(ads) and K F(des) values. These equations would facilitate an easy identification of soils vulnerable to antibiotics pollution, which would allow to program appropriate management practices to decrease undesirable effects on the environment and on public health., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

In the present work, laboratory column experiments were carried out to study the effect of pine bark amendment (at doses of 0, 12, 48 and 96 Mg ha -1 ) on the transport of three sulfonamide antibiotics (sulfadiazine -SDZ-, sulfamethazine -SMT-, and sulfachloropyridazine -SCP-) through two crop soils. All three sulfonamides showed high mobility in the unamend soils, with absence of retention in most cases. However, some differences were detected regarding the degree of interactions between sulfonamides and soils, being higher for soil 1, which was attributed to its higher organic carbon content. For both soils, interactions with the antibiotics studied followed the sequence SDZ < SMT < SCP, indicating an increase as a function of the hydrophobicity of sulfonamides. Pine bark amendment significantly increased the retention of the three sulfonamides in both soils. Specifically, in the case of soil 1, the incorporation of the highest dose of pine bark (96 Mg ha -1 ) caused that retention increased from 0% to 70.3% for SDZ, from 2.7% to 71.3% for SMT, and from 0% to 85.4% for SCP. This effect of pine bark is mainly attributed to its high organic carbon content (48.6%), including substances with potential to interact and retain antibiotics, as well as to its acidic pH (4.5). Therefore, pine bark amendment would be an effective alternative to reduce the transport of sulfonamides in soils and, thus, decrease risks of passing to other environmental compartments, as well as harmful effects on the environment and public health., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Taking into account environmental and public health issues due to emerging pollutants, and specifically to antibiotics spread into environmental compartments, this work focused on the competition among three tetracycline antibiotics (tetracycline, CT; oxytetracycline, OTC; and chlortetracycline, CTC) for adsorption sites in six different soils. Batch-type adsorption/desorption tests were carried out, with 24 h as contact time. The six soils were from two different farming areas, and were selected according to pH values and organic matter contents. Binary systems (pairs of antibiotics present simultaneously) were used to study competition, setting the dose of one antibiotic at 200 μmol L -1 , and varying the concentration of another from 50 to 600 μmol L -1 . In the case of the concentration of 200 μmol L -1 , the results of the binary systems were also compared with those obtained in simple and ternary systems. The results showed that those soils with the highest organic matter content (soils 50AL and 71S) adsorbed 100% of the three antibiotics, with desorption being <10% in all cases. The other four soils showed some degree of competition for adsorption sites in binary systems, with adsorption decreasing between 25 and 47% compared to simple systems, and with desorption increasing, especially in soils with higher pH and less organic matter. This competition was even more pronounced in ternary systems, affecting to these same soils, while the effects were very scarce in soils with higher organic matter content. The results indicate that most of the studied soils have high adsorption capacity for tetracycline antibiotics, retaining them with high energy even in the case of multiple systems. It was also shown that hysteresis affected adsorption/desorption processes. These results have relevance at environmental and social levels, given the growing concern regarding antibiotics pollution, and the need of promoting their retention and inactivation when spread in environmental compartments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Taking into account the high mobility and environmental risks due to sulfonamide antibiotics as emerging pollutants, batch-type experiments were performed to study adsorption/desorption of three sulfonamides (sulfadiazine -SDZ-, sulfamethazine -SMT- and sulfachloropyridazine -SCP-) in three agricultural soils. The study was carried out both for un-amended and amended soil samples, using different doses (0, 12, 24 and 48 Mg ha -1 ) of three different by-products (mussel shell, oak ash and pine bark). Adsorption on un-amended soils was rather low, with percentages between 11 and 45% for SDZ, 20-64% for SMT, and 19-65% for SCP. Both the Linear and Freundlich models fitted well to adsorption curves. In the case of un-amended soils, and regarding the Linear model, the values of the coefficient of distribution (K d , expressed in L kg -1 ) were between 0.6 and 1.3 for SDZ, between 0.7 and 1.1 for SMT, and between 0.6 and 2.6 for SCP. As regards the Freundlich model, the values of the adsorption constant (K F , expressed in L 1/n μmol 1-1/n kg -1 ), were in the range 0.4-1.9 for SDZ, 0.9-2.9 for SMT, and 1.2-3.8 for SCP. Simultaneously, desorption percentages were high, reaching 13.7-47.7% for SDZ, 12.6-35.1% for SMT, and 13.7-34.3% for SCP, when the highest initial antibiotic concentration (50 μmol L -1 ) was added, thus indicating low retention and high mobility for these compounds in soils. Mussel shell and oak ash amendments did not increase retention of any of the three sulfonamides. However, the incorporation of pine bark resulted in an increase in the adsorption and decrease in desorption for all three antibiotics. Specifically, for soils amended with pine bark at 48 Mg ha -1 , K d values (expressed in L kg -1 ) were between 2.1 and 2.9 for SDZ, between 3.4 and 3.6 for SMT, and between 2.5 and 8.2 for SCP. Regarding K F (expressed in L 1/n μmol 1-1/n kg -1 ), its values ranged from 5.6 to 6.3 for SDZ, 6.2-8.8 for SMT, and 5.3-7.1 for SCP. These scores were clearly higher than those of un-amended soils, and pine bark amendment also resulted in lower desorption percentages, ranging 8.7-11.4% for SDZ, 4.0-10.7% for SMT, and 6.5-16.9% for SCP. This positive effect on the retention of sulfonamides due to pine bark can be attributed to its high organic carbon content (48.6%), as well as to its acidic pH w (4.0). Therefore, pine bark amendment can be considered an effective alternative to increase the retention of sulfonamides in soils, thus reducing their bioavailability and transport to other environmental compartments, and subsequent risks of negative impacts on human and environmental health., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Adsorption and desorption processes were studied for the antibiotics sulfamethoxypyridazine (SMP) and enrofloxacin (ENR) in 20 agricultural soils devoted to wheat-potato and vine cultivation. Batch experiments were used to conduct kinetic studies, as well as to evaluate adsorption and desorption for different concentrations of antibiotics. The results indicated that adsorption curves were linear for SMP, while presented a certain curvature in the case of ENR. The adsorption of both antibiotics was fitted to a linear equation and to the Freundlich model. In the case of the linear equation, the values of the distribution coefficient K d were lower for SMP (0.9-26.0 L kg -1 ) than for ENR (121-2345 L kg -1 ). In the Freundlich model, the values of the adsorption constant K F ranged between 1.7 and 34.0 L n  μmol 1-n  kg -1 for SMP, and between 829 and 3019 L n  μmol 1-n  kg -1 for ENR. A multiple regression analysis showed that, in the case of SMP, 78% of the variance of the adsorption parameter K d was explained by soil organic carbon (SOC) and exchangeable magnesium (Mg e ) contents, while for ENR no significant relation was found. In addition, for SMP, 66% of the variance of K F was explained by SOC, and for ENR 45% of the variability of K F was explained by nitrogen content. Desorption rates were higher for SMP (reaching up to 24%) than for ENR (which reached up to 7%). Desorption percentages showed a potential relation with the adsorption parameter K d for both SMP and ENR. These results could be useful to elucidate the evolution and dynamics of these emerging pollutants in soils and other environmental compartments, which could be of aid in controlling public health risks associated to them., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Batch-type experiments were used to study adsorption-desorption of sulfadiazine in 50 crop soils exposed to antibiotic pollution due to the spreading of animal manure or slurry. Adsorption and desorption curves were linear, and were satisfactorily described using the linear and Freundlich equations. The Freundlich adsorption constant (K F(ad) ) showed low values (between 0.4 and 9.0 L 1/n μmol 1-1/n kg -1 ), which were similar to those of the adsorption constant for the linear model (K d(ad) , between 0.3 and 12.0 L kg -1 ). Furthermore, the desorption constant for the linear model (K d(des) ) showed higher values than those of K d(ad) , ranging between 1.6 and 29.3 L kg -1 , while the values of the Freundlich desorption constant (K F(des) ) ranged from 0.10 to 36.8 L 1/n μmol 1-1/n kg -1 . The percentages of adsorption were very variable, ranging from 10 to 87%. The soil characteristics that most influenced adsorption-desorption were those related to soil organic matter (organic carbon and nitrogen contents), as well as the effective cation exchange capacity, and pH. In addition, statistically robust pedotransfer functions were obtained, allowing prediction of adsorption-desorption behavior for sulfadiazine from readily determinable soil parameters, such as pH or organic carbon content., (Copyright © 2019 Elsevier B.V. All rights reserved.)

We studied competitive adsorption for the tetracycline antibiotics (TCs) tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) on three bio-adsorbents (mussel shell, oak wood ash, and pine bark). The results were compared for individual systems (with antibiotics added separately) and ternary systems (with all three antibiotics added simultaneously). In all cases batch-type experiments were carried out, with 24 h of contact time. In the individual systems, concentrations of 200 μmol L -1 were used for each of the three antibiotics, separately. In the ternary system, all three TCs were added simultaneously, using the following total concentrations: 50, 100, 200, 400, 600 μmol L -1 , each antibiotic being 1/3 of the total. Taking into account that ionic strength of a solution is related to a measure of the concentration of ions in that solution, the use of individual and ternary systems allows to compare, for each antibiotic, systems having equal concentrations and similar ionic strength (concentrations of 200 μmol L -1 ), and systems having different concentrations and ionic strength (200 μmol L -1 in the individual systems, and 600 μmol L -1 in the ternary systems, resulting from the sum of 200 μmol L -1 corresponding to each of the three antibiotics). Adsorption/desorption results indicated that these processes were in all cases closely related to pH values, and to carbon and non-crystalline minerals contents in the bio-adsorbents. Both oak ash and pine bark adsorbed close to 100% of TCs in individual and ternary systems, with desorption <4% for oak ash, and <12% for pine bark. However, mussel shell gave clearly poorer results, only relatively acceptable for CTC, with adsorption <56% and desorption even >30% for TC and OTC. In view of the results, oak ash and pine bark can be recommended as effective bio-adsorbents for the three TCs studied, and could be useful to retain/inactive them in wastes, and soil or liquid media receiving these emerging pollutants, thus reducing risks of damage for public health and the environment., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Batch-type experiments were used to study adsorption-desorption of three sulfonamides: sulfadiazine (SDZ) sulfachloropyridazine (SCP), and sulfamethazine (SMT), in five crop soils, whereas laboratory soil column experiments were employed to obtain data on transport processes. Adsorption results were satisfactorily adjusted to Linear and Feundlich equations, with R 2 values above 0.95. Adsorption followed the sequence SDZ < SMT < SCP, showing higher values for soils with higher levels of organic carbon (OC) content. Conversely, desorption was higher in soils with less OC, and lower in soils with higher OC contents. The temporal moment analysis method gave values for the transport parameters τ and R which were significantly correlated with soil parameters related to organic matter, specifically OC and N concentrations. The higher retention of the three sulfonamides in soils with high organic matter content is a relevant fact, with value when programming management practices in agricultural soils, and specifically in relation to the spreading of animal manures, slurries, or waste containing these emerging pollutants., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Antibiotics spread into the environment can cause soil and water degradation. Specifically, tetracycline antibiotics (TCs) are among those most consumed in veterinary medicine, and near 90% of the doses administered to animals are excreted as original compounds, due to poor absorption. In this study we investigated competitive soil adsorption/desorption for three tetracycline antibiotics (tetracycline: TC, oxytetracycline: OTC, and chlortetracycline: CTC), usually spread on soils by slurry fertilization, affecting to soil degradation due to chemical pollution. The study was carried out on six soils selected according to their pH values (4.49-7.06), and organic matter contents (1.07-10.92%). The competitive experiments were performed in ternary systems (adding all three TCs simultaneously, using five equal and increasing concentrations, from 17 to 200 μmol L -1 ). The results were compared with those obtained in simple systems (adding individual antibiotics separately), for the same final concentration (in this case, 200 μmol L -1 ) and for different concentrations (200 μmol L -1 in the simple systems, versus 600 μmol L -1 in the ternary systems, resulting from the sum of 200 μmol L -1 of each of the three antibiotics). In all cases, batch-type adsorption/desorption experiments were carried out, with 24 h as contact time. Those soils with higher organic matter content adsorbed 100% of the TCs, with desorption being always lower than 3%. In soils with less organic matter, adsorption decreased as the dose of added antibiotic increased, due to competition for adsorption sites. CTC was the most retained among the three TCs (up to 20% more than the other when high doses of antibiotic were added). In the simple systems, percentage adsorption was always high (>85%) for the three TCs; however, percentage adsorption decreased in the ternary systems, reaching just 65% and 40% (for equal and different ionic strength, respectively) in soils with low organic matter contents. These results show the environmental and public health relevance of competition among the three TCs. In fact, the highest risk of entering the food chain takes place when these antibiotics are spread together on soils with low organic matter content, especially in the case of TC and CTC, which are the least adsorbed and the most desorbed molecules., (Copyright © 2019 Elsevier Inc. All rights reserved.)

In this work, tetracycline (TC) adsorption and desorption were studied, and the soil properties that most influenced the process were identified. Batch experiments were carried out on 63 crop soil samples, which showed a wide range of values in their physicochemical characteristics. Adsorption curves fit well to the Freundlich equation, with K F values varying between 901 and 9202 L n μmol 1-n kg -1 . K d values ranged between 53 and 6899 L kg -1 for an initial concentration (C o ) of 400 μM, whereas the adsorption capacity (q a ) ranged from 8541 to 14,852 μmol kg -1 . TC retention on soils was high, with adsorption values always higher than 58%, and desorption values lower than 9%. Bivariate correlations and multiple linear regressions were performed to identify those soil variables having a greater influence on TC adsorption and desorption. The results indicate that organic carbon, clay, exchangeable aluminum, available phosphorus, effective cation exchange capacity content, and pH are the main characteristics affecting TC adsorption and desorption. The models, developed by means of multiple linear regression, gave satisfactory and robust predictions for TC adsorption and desorption, using easily determinable soil characteristics as input., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Total and available Cu and Zn levels were assessed in plant biomass, as well as in two rhizosphere fractions (tightly adhering rhizosphere (TAR), and loosely adhering rhizosphere (LAR)), in wild plants species from vineyard soils. Both TAR and LAR fractions were enriched in total Cu and Zn (1.7 and 1.6 times, respectively), and in available Cu and Zn (2.2 and 19.5 times, respectively), with the former being significantly higher for TAR than for LAR fractions. Mean values for total Cu accumulation in root and aerial biomass of the studied wild plants were 84 and 66 mg kg -1 , respectively, being 57 and 79 mg kg -1 for Zn. No correlations were found among metal contents in plant biomass and available Cu and Zn concentrations in the rhizosphere fractions. Translocation factor (TF) values for Zn (range 1.0-3.5) indicate preferential accumulation in the aerial biomass in all the studied wild plants. On the contrary, TF for Cu shows a greater variability, depending on plant species, and ranging from 0.2 to 5.9. Regarding bioaccumulation factor (BAF), ranges were 0.03-0.27 and 0.13-0.58, for Cu and Zn, respectively. Results suggest that D. sanguinalis, P. hieracioides, S. viridis, and T. barbata could be useful for Cu remediation in the studied soils, by means of phytostabilization processes., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Batch experiments were used to test P sorbent potential of soil samples, pyritic and granitic materials, mussel shell, mussel shell ash, sawdust, and slate waste fines for different pH and incubation times. Maximum P sorption varied in a wide range of pH: < 4 for pyritic material, 4-6 for forest soil, > 5 for slate fines, > 6 for shell ash, and pH 6-8 for mussel shell. P sorption was rapid (< 24 h) for forest soil, shell ash, pyritic material, and fine shell. On the opposite side, it was clearly slower for vineyard soil, granitic material, slate fines, pine sawdust, and coarse shell, with increased P sorption even 1 month later. For any incubation time, P sorption was > 90% in shell ash, whereas forest soil, pyritic material, and fine shell showed sorption rates approaching 100% within 24 h of incubation. These results could be useful to manage and/or recycle the sorbents tested when focusing on P immobilization or removal, in circumstances where pH changes and where contact time may vary from hours to days, thus aiding to diminish P pollution and subsequent eutrophication risks, promoting conservation and sustainability.

Antibiotics discharged to the environment constitute a main concern for which different treatment alternatives are being studied, some of them based on antibiotics removal or inactivation using by-products with adsorbent capacity, or which can act as catalyst for photo-degradation. But a preliminary step is to determine the general characteristics and magnitude of the degradation process effectively acting on antibiotics. A specific case is that of sulfonamides (SAs), one of the antibiotic groups most widely used in veterinary medicine, and which are considered the most mobile antibiotics, causing that they are frequently detected in both surface- and ground-waters, facilitating their entry in the food chain and causing public health hazards. In this work we investigated abiotic and biotic degradation of three sulfonamides (sulfadiazine -SDZ-, sulfachloropyridazine -SCP-, and sulfamethazine -SMT-) in aqueous media. The results indicated that, in filtered milliQ water and under simulated sunlight, the degradation sequence was: SCP > SDZ ≈ SMT. Furthermore, the rate of degradation clearly increased with the raise of pH: at pH 4.0, half-lives were 1.2, 70.5 and 84.4 h for SCP, SDZ and SMT, respectively, while at pH 7.2 they were 2.3, 9.4 and 13.2 h for SCP, SMT and SDZ. The addition of a culture medium hardly caused any change in degradation rates as compared to experiments performed in milliQ water at the same pH value (7.2), suggesting that in this case sulfonamides degradation rate was not affected by the presence of some chemical elements and compounds, such as sodium, chloride and phosphate. However, the addition of bacterial suspensions extracted from a soil and from poultry manure increased the rate of degradation of these antibiotics. This increase in degradation cannot be attributed to biodegradation, since there was no degradation in the dark during the time of the experiment (72 h). This indicates that photo-degradation constitutes the main removal mechanism for SAs in aqueous media, a mechanism that in this case was favored by humic acids supplied with the extracts from soil and manure. The overall results could contribute to the understanding of the environmental fate of the three sulfonamides studied, aiding to program actions that could favor their inactivation, which is especially relevant since its dissemination can involve serious environmental and public health risks., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Using batch-type experiments, chromium (Cr(VI)) and fluoride (F - ) sorption/desorption were studied in forest and vineyard soil samples, pyritic material, pine bark, oak ash, hemp waste and mussel shell, as well as on samples of forest and vineyard soil, and of pyritic material, individually treated with 48 t ha -1 of pine bark, oak ash, and mussel shell. Pine bark showed the highest Cr(VI) sorption (always > 97% of the concentration added) and low desorption (<1.5%). Pyritic material sorbed between 55 and 98%, and desorbed between 0.6 and 9%. Forest and vineyard soils, oak ash, mussel shell and hemp waste showed Cr(VI) sorption always < 32%, and desorption between 22 and 100%. Pine bark also showed the highest F - retention (sorption between 62 and 73%, desorption between 10 and 15%), followed by oak ash (sorption 60-69%, desorption 11-14%), forest soil (sorption 60-73%, desorption 19-36%), and pyritic material (sorption 60-67%, desorption 13-15%), whereas in vineyard sorption was 49-64%, and desorption 24-27%, and in hemp waste sorption was 26-36%, and desorption 41-59%. Sorption data showed better fitting to the Freundlich than to the Langmuir model, especially in the case of Cr(VI), indicating that multilayer sorption dominated. The addition of by-products to the forest and vineyard soils, and to the pyritic material, caused an overall increase in F - sorption, and decreased desorption. Furthermore, the pine bark amendment resulted in increases in Cr(VI) retention by both soils and the pyritic material. These results could be useful to favor the recycling of the by-products studied, aiding in the management of soils and degraded areas affected by Cr(VI) and F - pollution, and in the removal of both anions from polluted waters., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Veterinary antibiotics reaching soils and water bodies are considered emerging pollutants deserving special attention. In this work, dissipation of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) is investigated. Dissipation experiments in filtered water, using simulated sunlight, resulted in the following degradation sequence: TC < OTC ≈ CTC, with half-life values of 229, 101 and 104 min, respectively; however, no dissipation took place in the dark. Dissipation of the three tetracyclines in culture medium and with simulated sunlight was much higher, giving the sequence TC ≈ OTC < CTC, with half-lives of 9, 10 and 7 min, respectively; in the dark, TC and OTC did not suffer dissipation, but it was around 28% for CTC at the end of the experiment (480 min). The variable explaining a higher dissipation in culture medium and with light was pH, as this parameter caused changes in the distribution of species of tetracyclines, affecting degradation. Adding bacterial suspensions extracted from soil and poultry manure increased dissipation, giving the sequence: TC ≈ OTC < CTC, which is attributed to the presence of humic acids, which adsorb these antibiotics. These results could facilitate understanding the fate of antibiotics reaching environmental compartments and causing public health hazards., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The purpose of this work was to elucidate the repercussion of changing pH, incubation time and As(V) competition on fluoride (F - ) sorption on forest and vineyard soil samples, pyritic, and granitic materials, as well as on the by-products pine sawdust, oak wood ash, mussel shell ash, fine and coarse mussel shell, and slate processing waste fines. To reach this end, the methodological approach was based on batch-type experiments. The results indicate that, for most materials, F - sorption was very high at the start, but was clearly diminished when the pH value increased. However, oak wood ash and shell ash showed high F - sorption even at alkaline pH, and pine sawdust showed low F - sorption for any pH value. Specifically, F - sorption was close to 100% for both ashes at pH < 6, and around 70% at pH 10, while for forest soil it was close to 90% at pH < 2, and around 60% at pH values near 8. Regarding the effect of incubation time on F - sorption, it was very low for both soils, pyritic material, granitic material, and both kinds of ashes, as all of them showed very rapid F - sorption from the start, with differences being lesser than 10% between sorption at 30 min and 1 month of incubation. However, sawdust and slate fines sorbed 20% of added F - in 30 min, remaining constant up to 12 h, and doubling after 30 days. And finally, mussel shell sorbed 20% at 30 min, increasing to close to 60% when incubation time was 30 days. This means that some of the materials showed a first sorption phase characterized by rapid F - sorption, and a slower sorption in a second phase. As regards the effect of the presence of As(V) on F - sorption, it was almost negligible, indicating the absence of competition for sorption sites. In view of that all, these results could aid to appropriately manage soils and by-products when focusing on F - removal, in circumstances where pH value changes, contact time vary from hours to days, and potential competition between F - and As(V) could take place.

Aiming to investigate the efficacy of different materials as bio-sorbents for the purification of As-polluted waters, batch-type experiments were employed to study As(V) sorption and desorption on oak ash, pine bark, hemp waste, mussel shell, pyritic material, and soil samples, as a function of the As(V) concentration added. Pyritic material and oak ash showed high sorption (90% and >87%) and low desorption (<2% and <7%). Alternatively, hemp waste showed low retention (16% sorption and 100% desorption of the amount previously sorbed), fine shell and pine bark sorbed <3% and desorbed 100%, the vineyard soil sample sorbed 8% and released 85%, and the forest soil sample sorbed 32% and desorbed 38%. Sorption data fitted well to the Langmuir and Freundlich models in the case of both soil samples and the pyritic material, but only to the Freundlich equation in the case of the various by-products. These results indicate that the pyritic material and oak ash can be considered efficient As(V) sorbents (thus, useful in remediation of contaminated sites and removal of that pollutant), even when As(V) concentrations up to 6 mmol L -1 are added, while the other materials that were tested cannot retain or remove As(V) from polluted media., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

The European Community Bureau of Reference method (BCR) was used for evaluating the effects of pine bark amendment (0, 24 and 48 g kg -1 ) and ageing (1 and 30 days) on Cd, Cu, Ni, Pb and Zn fractionation, on samples from an acid mine soil. In addition, the stirred flow chamber technique was applied for analyzing heavy metals desorption from the unamended and pine bark amended mine soil. When the unamended soil were not subjected to ageing, the added heavy metals were mainly accumulated as soluble fraction (>90% for Cd, Ni and Zn; 71% for Cu; and 45% for Pb). Pine bark amendment and ageing had little effect on Cd, Ni and Zn fractionation, whereas important changes were detected for Cu and Pb in response to both pine bark amendment and ageing (decrease in the soluble fractions, and increase in less mobile fractions). Desorption experiments showed that both pine bark amendment and ageing decreased heavy metals release from the mine soil. The results of this study indicate that pine bark amendment could be used to increase heavy metals retention (especially in the case of Cu and Pb) in acid mine soils, thus reducing the risks of metal transfer to uncontaminated environmental zones., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Focusing on simultaneous arsenic and chromium pollution, we used batch-type experiments to study As(V)/Cr (VI) competitive sorption on soil samples, pyritic material, mussel shell, oak ash, pine bark and hemp waste, as well as on binary mixtures (50 % mussel shell and 50 % another material-oak ash, pine bark, or hemp waste), and on forest and vineyard soil samples and pyritic material amended with 48 t ha -1 of mussel shell, oak ash, pine bark, or hemp waste. Equal As(V) and Cr(VI) concentrations (0 to 6 mmol L -1 ) were added to the individual materials, binary mixtures, and 48 t ha -1 amended materials. The individual forest soil sample, pyritic material, and oak ash showed clearly higher As(V) sorption, whereas Cr(VI) sorption was higher on pine bark. Sorption was up to 50 % higher for As(V) than for Cr(VI) on the forest soil sample, oak ash, and pyritic material, while pine bark sorbed 95 % more Cr(VI). Regarding binary mixtures, the presence of mussel shell increased As(V) sorption on pine bark and Cr(VI) sorption on hemp waste. As regards the amendments, in the case of the forest soil sample, the amendments with oak ash and mussel shell increased As(V) sorption, while pine bark amendment increased Cr(VI) sorption; in the vineyard soil sample, the mussel shell amendment increased As(V) sorption; in the pyritic material, pine bark amendment increased Cr(VI) sorption. These results could be useful to appropriately manage the soils and individual or mixed by-products assayed when As(V) and Cr(VI) pollution occurs.

The use of organic biosorbents for anion removal from water has been less studied than for cationic compounds. In this work, the removal capacity of pine bark for potential anionic pollutants (fluoride, phosphate, arsenate and dichromate) was assessed in column experiments, designed to study the process of transport. The results showed that pine bark has a very low retention capacity for phosphate, arsenate or fluoride, and in turn, very high for dichromate, with retention values close to 100% and less than 2% desorption of the adsorbed dichromate. The large differences observed between anions suggest that differences in the retention mechanism of each anion exist. In the case of phosphate and arsenate, electrostatic interactions with the mostly negatively charged functional groups of the pine bark determine the low retention capacity. Dichromate retention might proceed through reduction of chromium (VI) to chromium (III), what improves the efficiency of the removal., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We study As(V)/Cr(VI) competitive sorption on a forest soil, a vineyard soil, pyritic material, mussel shell, pine bark, oak ash, and hemp waste, adding variable As(V) and Cr(VI) concentrations or displacing each pollutant with the same concentration of the other. When using variable concentrations, As(V) showed more affinity than Cr(VI) for sorption sites on most materials (sorption up to >84 % on oak ash and pyritic material). The only exception was pine bark, with clearly higher Cr(VI) sorption (>90 %) for any Cr(VI)/As(V) concentration added. Regarding the displacement experiments, when As(V) was added and reached sorption equilibrium, the subsequent addition of equal Cr(VI) concentration did not cause relevant As displacement from oak ash and pyritic material, indicating strong As bindings, and/or low competitive effects. When Cr(VI) was added and reached sorption equilibrium, the subsequent addition of equal As(V) concentration caused Cr(VI) displacement from all materials except pine bark, indicating weak Cr bindings. In view of these results, oak ash and the pyritic material could be used to remove As(V) in concentrations as high as 6 mmol L(-1), even in the presence of a wide range of Cr(VI) concentrations, whereas pine bark could be used to remove Cr(VI) concentrations as high as 6 mmol L(-1). The other materials assayed (including hemp waste, studied for the first time as As(V) and Cr(VI) bio-sorbent) cannot be considered appropriate to remove As(V) and/or Cr(VI) from polluted media.

Bark from Pinus pinaster is one of the most abundant forestry wastes in Europe, and among the proposed technologies for its reutilization, the removal of heavy metals from wastewater has been gaining increasing attention. In this work, we have studied the performance of pine bark for heavy metal biosorption on competitive systems. Pb, Cu, Ni, Zn and Cd sorption and desorption at equilibrium were studied in batch experiments, whereas transport was studied in column experiments. Batch experiments were performed adding simultaneously different concentrations (0.08-3.15mM) of two or more metals in solution to pine bark samples. Column experiments were performed with 10mM solutions of two metals or a 5mM solution of the five metals. In general, the results under competitive conditions were different to those obtained in monoelemental experiments. The multi-metal batch experiments showed the adsorption sequence Pb≈Cu>Cd>Zn>Ni for lower metal doses, Pb>Cu>Cd>Zn>Ni for intermediate doses, and Pb>Cu>Cd≈Zn≈Ni for high metal doses. Desorption followed the sequence PbCu>Zn>Cd>Ni. The presence of a second metal affected the transport of all the elements studied except Pb, and confirmed the strong influence of Pb and Cu on the retention of the other metals. These results can help to appropriately design decontamination systems using this forestry waste., (Copyright © 2016 Elsevier Inc. All rights reserved.)

We study the influence of phasing out a cement plant on the heavy metal (Hg, Pb and Cr) content in the surrounding soils, taking into account factors often neglected, such as contributions due to local lithology or land use. The range of total Hg was 10-144µg kg(-1), reaching up to 41 and 145mgkg(-1) for total contents of Pb and Cr, respectively. Forest soils showed higher concentration of Hg than prairie soils, indicating the importance of land use on the accumulation of volatile heavy metals in soils. In forest soils, total Hg showed a trend to decrease with soil depth, whereas in prairie soils the vertical pattern of heavy metal concentrations was quite homogeneous. In most cases, the distance to the cement plant was not a factor of influence in the soils content of the analyzed heavy metals. Total Pb and Cr contents in soils nearby the cement plant were quite similar to those found in the local lithology, resulting in enrichment factor values (EF's) below 2. This suggests that soil parent material is the main source of these heavy metals in the studied soils, while the contribution of the cement plant to Pb and Cr soil pollution was almost negligible. On the contrary, the soils surrounding the cement plant accumulate a significant amount of Hg, compared to the underlying lithology. This was especially noticeable in forest soils, where Hg EF achieved values up to 36. These results are of relevance, bearing in mind that Hg accumulation in soils may be an issue of environmental concern, particularly in prairie soils, where temporal flooding can favor Hg transformation to highly toxic methyl-Hg. In addition, the concurrence of acid soils and total-Cr concentrations in the range of those considered phytotoxic should be also stressed., (Copyright © 2016 Elsevier B.V. All rights reserved.)

We used batch-type experiments to study F sorption/desorption on a forest soil, a vineyard soil, pyritic material, granitic material, finely and coarsely ground mussel shell, mussel shell calcination ash, oak wood ash, pine-sawdust, slate processing fines, and three different mixtures that included three components: sewage sludge, mussel shell ash, and calcined mussel shell or pine wood ash. The three waste mixtures, forest soil, pyritic material, and shell ash showed high sorption capacity (73-91 % of added F) and low desorption, even when 100 mg F L(-1) was added. All these materials (and to a lower extent wood ash) could be useful to remove F from polluted media (as certain soils, dumping sites, and contaminated waters). The vineyard soil, the granitic material, mussel shell, slate fines, and pine-sawdust were less effective in F removal. In most cases, sorption data fitted better to the Freundlich than to the Langmuir equation. These results can be useful to program the correct management of the soils, by-products, and waste materials assayed, mostly in situations where F concentrations are excessive and F removal should be promoted.

The potential utilization of pine bark as a biosorbent for the treatment of metal-contaminated soils and waters has been evaluated in transport experiments using laboratory columns. Solutions containing the metals Cu, Pb, Zn, Ni or Cd, each one individually and at three different concentrations (2.5, 10 and 25 mM) were tested. Pine bark affected metal transport and the breakthrough curves, producing a reduction of their concentrations in the solution and a clear retardation with respect to an inert tracer. At metal concentrations equal to 2.5 mM, 100% of the assayed elements were removed from the solution in the pine bark column. At the 10 mM metal concentration, the percentage of metals retained fell to 38-67% of the amount added, whereas at the 25 mM metal concentration, only 16-43% was retained. In all cases, the highest retention capacity corresponded to Pb, and the lowest to Zn, whereas Cu, Cd and Ni produced intermediate comparable results. The analysis of the pine bark within the columns after the transport experiment showed that the metals entering the column adsorb progressively until a saturation concentration is reached in the whole column, and only then they can be released at significant concentrations. This saturation concentration was approximately 70 mmol kg(-1) for Cd, Ni and Zn, 100 mmol kg(-1) for Cu, and 125 mmol kg(-1) for Pb. Overall, our experiments have shown the high effectiveness of pine bark to retain the assayed metals in stable forms of low mobility., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Batch-type experiments were used to study competitive As(V) and P sorption on various soils and sorbent materials. The materials assayed were a forest soil, a vineyard soil, pyritic material, granitic material, coarsely and finely ground mussel shell, calcinated mussel shell ash, pine sawdust and slate processing fines. Competition between As(V) and P was pronounced in the case of both soils, granitic material, slate fines, both shells and pine sawdust, showing more affinity for P. Contrary, the pyritic material and mussel shell ash showed high and similar affinity for As(V) and P. These results could be useful to make a correct use of the soils and materials assayed when focusing on As and P removal in solid or liquid media, in circumstances where both pollutants may compete for sorption sites.

The objective of this work was to study the competitive adsorption/desorption of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) on two acid soils. We used the stirred flow chamber technique to obtain experimental data on rapid kinetic processes affecting the retention/release of the antibiotics. Both adsorption and desorption were higher on soil 1 (which showed the highest carbon, clay and Al and Fe oxides content) than on soil 2. Moreover, hysteresis affected the adsorption/desorption processes. Experimental data were fitted to a pseudo-first order equation, resulting qamax (adsorption maximum) values that were higher for soil 1 than for soil 2, and indicating that CTC competed with TC more intensely than OTC in soil 1. Regarding soil 2, the values corresponding to the adsorption kinetics constants (ka) and desorption kinetics constants for fast sites (kd1), followed a trend inverse to qamax and qdmax respectively. In conclusion, competition affected adsorption/desorption kinetics for the three antibiotics assayed, and thus retention/release and subsequent transport processes in soil and water environments., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The objective of this work was to study Cr(VI) sorption/desorption on two by-products from the wood industry: pine sawdust and oak wood ash. The retention/release experiments were carried out using standard batch-type trials. In the sorption-phase experiments, pine sawdust showed 23% sorption when a concentration of 100 mg Cr(VI)ŸL-1 was added, whereas sorption on oak wood ash was 17%. In the desorption-phase, chromium release was clearly higher from pine sawdust than from oak wood ash (98% and 66%, respectively). Sorption curves were well fitted to the Freundlich and Lineal models. In view of the results, both materials can be considered of very limited value to remove Cr from polluted soil and water, which can be of relevance regarding its appropriate use as biosorbents and recycled by-products.

The purpose of this work was to quantify retention/release of tetracycline, oxytetracycline, and chlortetracycline on two soils, paying attention to sorption kinetics and to implications of the adsorption/desorption processes on transfer of these pollutants to the various environmental compartments. We used the stirred flow chamber (SFC) procedure to achieve this goal. All three antibiotics showed high affinity for both soils, with greater adsorption intensity for soil 1, the one with the highest organic matter and Al and Fe oxides contents. Desorption was always <15%, exhibiting strong hysteresis in the adsorption/desorption processes. Adsorption was adequately modeled using a pseudo first-order equation with just one type of adsorption sites, whereas desorption was better adjusted considering both fast and slow sorption sites. The adsorption maximum (qmax) followed the sequence tetracycline > oxytetracycline > chlortetracycline in soil 1, with similar values for the three antibiotics and the sequence tetracycline > chlortetracycline > oxytetracycline in soil 2. The desorption sequences were oxytetracycline > tetracycline > chlortetracycline in soil 1 and oxytetracycline > chlortetracycline > tetracycline in soil 2. In conclusion, the SFC technique has yielded new kinetic data regarding tetracycline, oxytetracycline, and chlortetracycline adsorption/desorption on soils, indicating that it can be used to shed further light on the retention and transport processes affecting antibiotics on soils and other media, thus increasing knowledge on the behavior and evolution of these pharmaceutical residues in the environment.

The objective of this work was to determine the retention of five metals on pine bark using stirred flow and batch-type experiments. Resulting from batch-type kinetic experiments, adsorption was rapid, with no significant differences for the various contact times. Adsorption was between 98 and 99% for Pb(2+), 83-84% for Cu(2+), 78-84% for Cd(2+), 77-83% for Zn(2+), and 70-75% for Ni(2+), and it was faster for low concentrations, with Pb suffering the highest retention, followed by Cu, Cd, Ni and Zn. The fitting to the Freundlich and Langmuir models was satisfactory. Desorption increased in parallel to the added concentrations, with Pb always showing the lowest levels. Stirred flow chamber experiments showed strong hysteresis for Pb and Cu, sorption being mostly irreversible. The differences affecting the studied heavy metals are mainly due to different affinity for the adsorption sites. Pine bark can be used to effectively remove Pb and Cu from polluted environments., (Copyright © 2014 Elsevier Ltd. All rights reserved.)