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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.)

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.)

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 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.)

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.

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.

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 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.

Batch type and column experiments were used to study competitive adsorption-desorption and transport for Cd, Cu, Ni and Zn in a mine soil, both un-amended and amended with mussel shell. Batch type experiments showed that adsorption was affected by the added concentration of the metals, generally following the sequence Cu>Zn>Cd≈Ni. Metal desorbed was a function of the dose of metal added, as well as of the dose of shell amendment, being relevant that even when the highest dose of metal (2300 μM) was added, the 24 g kg(-1) shell amendment caused a drastic diminution in the amount of metal desorbed. Column experiments showed that even the lowest dose of the shell amendment (6 g kg(-1)) caused a strong retention of the 4 heavy metals assayed, whereas using the 24 g kg(-1) shell amendment no metal was detected in the effluent during the time of the experiment. The mass of metal retained in the un-amended soil was very different for the various metals assayed, but the amendment with 6 g kg(-1) shell increased this retention in all cases, and the 24 g kg(-1) amendment caused almost 100% retention for all 4 metals. The retardation factor (R) suffered an overall increase as a function of the shell dose; the profile distribution of the 4 heavy metals was homogeneous through the un-amended soil into the column, but the shell amendment clearly decreased the solute transport affecting these metals, causing its concentration in the first centimeters of the soil profile., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

As(V) retention capacity is determined by means of adsorption/desorption trials performed for coarse and fine ground mussel shell, forest and vineyard soils with or without fine shell, pine wood ash, oak wood ash, pine sawdust and slate-processing fines. Pine ash shows the highest arsenic retention potential (with >97 % adsorption and ≤1 % desorption), followed by shell-amended forest soil (adsorption between 96 and 92 %), by un-amended forest soil (adsorption between 98 and 86 %) and by the amended vineyard soil (adsorption between 92 and 75 %). Sawdust is the material with the lowest arsenic retention capacity in most cases, with un-amended vineyard soil also showing poor results. In the case of oak ash, As(V) percentage adsorption becomes higher with increasing added arsenic concentrations, while this increase in added arsenic causes lower percentage adsorption in the case of slate fines. Regarding adsorption ability, As(V) adsorption data were fitted to Freundlich and Langmuir models, showing good fitting, with pine ash and shell-amended forest soil having the highest K F values. In view of that, mussel shell amendment would be useful to increase arsenic retention on forest and vineyard soils, while pine ash could be used to retain arsenic even from wastewaters.

The aim of the present study was to determine how the addition of cattle slurry (S), cattle slurry mixed with sawdust and lime (SL) or cattle slurry mixed with sawdust and crushed (2-4 mm) mussel shells (SM), coming from livestock litter affected the chemical properties of an acid soil and the production in a grass/corn rotation. Bulk and rhizospheric soil were analysed. With respect to the not-treated soil, all the treatments increased pH, exchangeable cations and ECEC, and decreased total N, organic C and exchangeable Al. The lowest variations were observed in S treated plots, while considerable variations occurred in the corn plots treated with SM. In this case, the soil pH reached values up to 6.7, in contrast with the S treated plots that reached pH 5.9. An increase in the concentrations of Ca, Mg and K was also observed. These effects were more evident in the rhizosphere than in the bulk. The addition of both lime and crushed shells increased production and quality of the yield. In SL and SM treated plots the total production of grass was 3.5 to 4-fold the production obtained in S plots. The total production of corn increased by 1095 kg ha(-1) in the SL-treated plots and 2559 kg ha(-1) in SM plots; almost all these increments of production were due to the augmented production of cob. We concluded that the use of crushed mussel shells can be recommended as livestock litter suitable to be distributed in acid soils.