Impact of fertilization with pig slurry on the isotopic composition of nitrate retained in soil and leached to groundwater in agricultural areas

The isotopic composition of N and O of nitrate (NO3−) is usually employed to trace its sources of pollution in groundwater. In agricultural areas, the amount of NO3− that reaches the aquifers after fertilization is controlled by different transformation processes that can affect the nitrogen species isotopic composition. Aiming to address the reliability of using isotope tools to trace sources of groundwater NO3−, the goal of this study was to check the effect of fertilization on the isotopic composition of N compounds retained and leached from soils. The concentration and isotopic composition (δ15N and δ18O) of ammonium (NH4+), NO3− and nitrite (NO2−) was characterized after the application of pig slurry in lysimeters containing either soil under fallow (LF) or the same soil continuously cropped and fertilized (LC) during the previous six years. Results showed that the leached NO3− isotopic signature did not directly reflect the isotopic composition of the applied pig slurry. Just after fertilization, nitrification led to lower δ15NNO3 values in soil extracts and leachates (e.g. from +5.9 ± 0.9¿ to +3.8 ± 3.1¿ in soil extracts of LF lysimeters). These values increased after complete nitrification (+11.5 ± 1.3¿) towards the δ15Nbulk of pig slurry (+19.6 ± 0.5¿). Later on, due to soil organic matter and plant debris mineralization and subsequent nitrification, values decreased towards the initial δ15NNO3 of soil but remained above them (+8.6 ± 1.0¿). Both LF and LC experiments showed a similar trend and the latter ones allowed to reinforce that long-term fertilization with pig slurry can increase the soil δ15NNO3. Concerning the δ18O of NO3− from soil extracts and leachates, it mainly depended on the δ18O of irrigation water and oxygen, after nitrification of NH4+ from pig slurry. Therefore, studies aiming to trace groundwater NO3− pollution sources in rural areas by using an isotopic approach should consider the fertilization history of each setting. Also, analyzing the δ15Nbulk of soil is recommended, since it could mask the isotopic signature of the N applied through fertilization

Long-term effects of gasification biochar application on soil functions in a Mediterranean agroecosystem: Higher addition rates sequester more carbon but pose a risk to soil faunal communities

17 Pág. Departamento de Medio Ambiente y Agronomía​ (INIA)Biochar applications can have important implications for many of the soil functions upon which agroecosystems rely, particularly regarding organic carbon storage. This study evaluated the impacts of adding a highly aromatic gasification biochar at different rates (0, 12 and 50 t ha-1) to a barley crop on the provision of crucial soil functions (carbon sequestration, water content, greenhouse gas emissions, nutrient cycling, soil food web functioning, and food production). After natural ageing in the field for six years, a wide range of soil properties representative of the studied soil functions were measured and integrated into a soil quality index. Results showed that C sequestration increased with biochar rate (23 and 68% higher than in the control for the 12 and 50 t biochar ha-1 treatments, respectively). Water content was enhanced at the 50 t ha-1 treatment depending on the sampling date. Despite biochar additions neither abating nor increasing CO2 equivalent emissions (carbon dioxide plus nitrous oxide and methane), the system shifted from being a methane sink (-0.017 ± 0.01 mg CH4-C m-2 h-1 at the 12 t ha-1 treatment), to a net source (0.025 ± 0.02 mg CH4-C m-2 h-1 at the 50 t ha-1 treatment). In addition, biochar ageing provoked a loss of nitrate mitigation potential, and indeed ammonium production was stimulated at the 50 t ha-1 rate. The 50 t ha-1 treatment also adversely affected nematode and collembolan functional diversity. Lastly, biochar did not affect barley yield. The results of the soil quality index indicated that no biochar treatment provided more benefits to our agricultural soil, and, although the 50 t ha-1 treatment increased C sequestration, this was potentially offset by its harmful effects on soil faunal communities. Therefore, application of this biochar at high rates should be avoided to prevent risks to soil biological communities.We gratefully acknowledge the funding by the project FERTICHAR (AGL2015-70393-R) of the Spanish Ministry of Economy and Competitiveness. We are also grateful to Dr. van den Brink, P. J., and Dr. Šmilauer, P. for their assistance on PRC analysis interpretation and proper use of CANOCO 5, respectively.Peer reviewe

Environmental benefits of using biochar as an amendment in pineapple cultivation in Costa Rica: soil physicochemical and biological effects and interaction with agrochemicals

La producció de pinya tropical és una activitat econòmica important a Costa Rica, l’àrea de cultiu de la qual ha augmentat significativament en les dues darreres dècades, i amb una significativa generació de residus agroindustrials i ús intensiu de plaguicides com els herbicides bromacil i diuron. Tots dos han estat detectats en aigües superficials i subterrànies, causant problemes ambientals, de salut i econòmics, malgrat que hi ha poca informació sobre el seu destí ambiental en sòls tropicals. La transformació de residus agroindustrials en biocarbó (biochar) mitjançant piròlisi i la seva adició al sòl com a esmena han estat proposats com una pràctica útil per a la gestió de residus que permet la millora de la qualitat del sòl, el segrestament de carboni i una possible mitigació de la mobilitat de plaguicides. L’objectiu de la tesi fou avaluar els beneficis i eventuals efectes no desitjats de l’adició de biocarbó a un sòl costa-riqueny cultivat amb pinya en combinació amb bromacil o diuron, considerant tant els seus efectes en el destí i eficiència com els ecotoxicològics. Els materials carbonitzats (MC) s’obtingueren per piròlisi a 300 o 600 ºC durant una hora, utilitzant com a materials de partida rostoll de pinya tropical (PS), “”pinzote”” de palmera d’oli (PF) i l’endocarp del fruit de café (cascarilla) (CH), que es van caracteritzar fisicoquímicament i es van aplicar al sòl a dosis d’aplicació de 10 i 20 t ha-1. S’avaluà la sorció, la degradació i la biodegradació dels plaguicides en condicions de laboratori, permetent la predicció del seu risc ambiental amb l’índex de classificació d’impacte de plaguicides. Addicionalment, es van avaluar efectes en l’emergència i creixement de d’enciam (Lactuca sativa), el desenvolupament d’invertebrats (el col·lèmbol Folsomia candid i l’enquitreid Enchytraeus crypticus) i la diversitat funcional de la comunitat dels microorganisms (MicrorespTM) per a provar possibles efectes dels MC en l’eficiència dels herbicides i en organismes terrestres no diana. Els MC a 300 ºC es classificaren com a materials torrefactes (MT) i a 600 ºC com a biocarbons (B). Els biocarbons presentaren major superfície específica, contingut de carboni fixe i pH que els MT, alhora que els PS-B i PF-B tenien major abundància de grups oxigenats superficials que CH-B i que tots els MT. Es va demostrar una sorció dèbil al sòl en tots dos plaguicides, fet que suggereix una elevada mobilitat, i la degradació i biodegradació del bromacil fou limitada en comparació al diruon. L’adició de biocarbó incrementà la persistència del bromacil, i els PS-MT i PF-MT la sorció del diuron. No obstant, això no va canviar la mobilitat i toxicitat aquàtica predites pels pesticides. L’adició de MC no reduí l’eficiència dels herbicides, però augmentà l’emergència sense incrementar el creixement. L’aplicació d’herbicides no causà efectes tòxics en col·lèmbols o enquitreids, sinó que promogué la reproducció sense afectar la supervivència. S’observà una evitació generalitzada de les barreges sòl-MC en enquitreids contrària a la preferència dominant en col·lèmbols, independentment de la presència d’herbicides. Finalment, no aparegueren canvis en la diversitat funcional microbiana amb l’adició d’herbicides o MC, llevat de l’increment en la taxa de consum d’alguns substrats en algunes barreges sòl-MC tractades amb diuron. En conclusió, l’adició de MC no canvià l’eficiència dels herbicides ni el seu destí en l’Ultisol tropical argilós estudiat. Sota la gestió habitual del cultiu de la pinya a la regió nord de Costa Rica, tots dos herbicides presentaren un elevat risc ambiental per a aigües superficials i subterrànies, i malgrat que l’adició de MC no ho va mitigar, no van causar efectes negatius sinó una millora del sòl com a hàbitat per a invertebrats edàfics.La producción de piña es una actividad económica importante en Costa Rica que ha aumentado significativamente su área cultivada en las dos últimas décadas, con una alta generación de residuos agroindustriales y un uso intensivo de plaguicidas, incluidos los herbicidas bromacil y diurón. Ambos se han detectado en aguas superficiales y subterráneas, lo que ha causado problemas ambientales, de salud y económicos, aunque aún existe poca información sobre su destino ambiental en los suelos tropicales. La transformación de residuos agroindustriales en biocarbón (biochar) mediante pirólisis y su adición al suelo como enmienda, se ha propuesto como una práctica útil de gestión de residuos capaz de mejorar la calidad del suelo, el secuestro de carbono y que podría mitigar la movilidad de los plaguicidas. El objetivo de la tesis fue evaluar los beneficios y eventuales efectos no deseados de la adición de biocarbón a un suelo costarricense cultivado con piña en combinación con bromacil o diuron, considerando tanto sus efectos ecotoxicológicos como en su destino y eficiencia. Los materiales carbonizados (MC) se obtuvieron pirolizando a 300 o 600 °C durante una hora rastrojo de piña (PS), pinzote de palma aceitera (PF) y cascarilla de café (CH), se caracterizaron física y químicamente y se mezclaron con suelo en dosis de aplicación equivalentes a 10 y 20 t ha-1. Se evaluaron la sorción, la degradación y la biodegradación de ambos plaguicidas en condiciones de laboratorio con lo que se predijo su riesgo ambiental con el Índice de Clasificación de Impacto de Plaguicidas. Además, se midió la emergencia y el crecimiento de la lechuga (Lactuca sativa), el desarrollo de invertebrados (colémbolo Folsomia candida; enquitréido Enchytraeus crypticus) y la diversidad funcional de los microorganismos (Microresp™) para probar los efectos de los MC en la eficiencia de los herbicidas y sobre organismos terrestres no diana. Los MC a 300 °C se clasificaron como materiales torrefactos (MT) y a 600 °C como biocarbones (B). Los biocarbones mostraron mayor superficie específica, contenido de carbono fijo y pH que los MT, mientras que los PS-B y PF-B presentaron mayor abundancia de grupos funcionales oxigenados superficiales que el CH-B y que todos los MT. Se observó una sorción débil de ambos plaguicidas en el suelo, lo que sugiere una alta movilidad, mientras que la degradación y biodegradación de bromacil fue limitada comparada con el diurón. La adición de biocarbón aumentó la persistencia del bromacil, mientras que los PS-MT y PF-MT aumentaron la sorción del diurón. No obstante, la movilidad y la toxicidad acuática predichas de los herbicidas no se afectaron. La adición de MC no redujo la eficiencia de los herbicidas, pero aumentó la emergencia sin mejorar el crecimiento. La aplicación de herbicidas no tuvo efectos tóxicos sobre colémbolos o enquitréidos pues promovió su reproducción sin afectar la supervivencia. Hubo una evitación generalizada de los enquitréidos de las mezclas suelo-MC opuesta a la preferencia general de los colémbolos, independientemente de la presencia de herbicidas. Finalmente, no se demostraron cambios en la diversidad funcional microbiana por la adición de herbicidas o MC, y solo se observó un aumento en la tasa de consumo de algunos sustratos en algunas mezclas suelo-MC tratados con diurón. En conclusión, la adición de MC no cambió la eficiencia de los herbicidas ni su destino en el Ultisol tropical arcilloso estudiado. Bajo la gestión habitual del cultivo de la piña en la Región Norte de Costa Rica, ambos herbicidas presentaron un elevado riesgo ambiental para aguas superficiales y subterráneas, y pese a que la adición de MC no le mitigar, no causaron efectos negativos sino una mejora del suelo como hábitat para invertebrados edáficos.Pineapple production is an important economic activity in Costa Rica as shown by the increase in its cropped area in the last two decades. It involves a high generation of agro-wastes as well as an intensive application of pesticides, including the herbicides bromacil, and diuron. Their use is associated with problems of environmental, health and economic concern, because it has been detected in both surface water and groundwater. However, there is still scarce information about the environmental fate of these herbicides in tropical soils. The transformation of this agro-waste surplus by pyrolysis into biochar, a carbonaceous material, followed by its addition to soil as an amendment, has been suggested as a useful waste management practice. This is because it may improve the soil quality and carbon sequestration and potentially mitigate the mobility of pesticides. The aim of this thesis was to evaluate the benefits and unexpected effects of biochar addition to a Costa Rican agricultural soil cropped to pineapple, concurrently considering the effects on bromacil and diuron fate and efficiency as well as non-target soil ecotoxicological effects. For this purpose, pineapple stubble (PS), oil palm fiber (PF) and coffee hulls (CH) were pyrolyzed at 300 or 600 °C for one hour and then physically and chemically characterized. Mixtures of the charred materials (CM) with soil were prepared at application rates equivalent to 10 and 20 t ha-1. Sorption, degradation, and biodegradation of both pesticides were evaluated in the laboratory, and the results were used to predict their environmental risk with the Pesticide Impact Rating Index. In addition, lettuce emergence and growth (Lactuca sativa), invertebrates performance (collembolan Folsomia candida; enchytraeid Enchytraeus crypticus), and microorganism functional diversity (Microresp™) were used to test the effects of CM on the herbicides’ efficiency and on the non-target soil biological groups. CM pyrolyzed at 300 °C were classified as torrefied materials (TM), while those pyrolized at 600 °C were classified as biochars (B). Biochars showed higher specific surface area, fixed carbon content and pH values than TM, while PS-B and PF-B presented a higher abundance of surface oxygenated chemical groups than CH-B and all the TM. A weak sorption of both herbicides to soil was observed suggesting a high mobility, while the degradation and biodegradation of bromacil was more limited compared to that of diuron. The addition of biochars increased the persistence of bromacil, while PS-TM and PF-TM increased the sorption of diuron. Despite that, the predicted mobility and aquatic toxicity of the herbicides were unaffected. The addition of CM did not reduce herbicide efficiency but increased seedling emergence without improving growth. The adding of herbicides had no toxic effects on collembolans and enchytraeids as it promoted their reproduction without affecting survival. A generalized avoidance of CM-mixtures by enchytraeids was observed as opposed to the general preference shown in collembolans, irrespective of the supplementation or not of herbicides. Finally, no changes in the microbial functional diversity by the sole addition of herbicides or CM were demonstrated, and a significant increase in the consumption rate of some substrates was observed only in some diuron-treated CM-mixtures. In summary, the addition of CM did not change the efficiency of the herbicides nor their fate in a tropical clay Ultisol. Under pineapple cropping conditions of the northern region of Costa Rica, bromacil and diuron presented a high estimated environmental risk to surface water and groundwater, and the addition of CM did not change this risk. Simultaneously, no negative effects to the soil ecosystem were observed, but there was an improvement in soil as a habitat for some soil invertebrates.Universitat Autònoma de Barcelona. Programa de Doctorat en Ecologia Terrestr

Environmental benefits of using biochar as an amendment in pineapple cultivation in Costa Rica : soil physicochemical and biological effects and interaction with agrochemicals

La producció de pinya tropical és una activitat econòmica important a Costa Rica, l'àrea de cultiu de la qual ha augmentat significativament en les dues darreres dècades, i amb una significativa generació de residus agroindustrials i ús intensiu de plaguicides com els herbicides bromacil i diuron. Tots dos han estat detectats en aigües superficials i subterrànies, causant problemes ambientals, de salut i econòmics, malgrat que hi ha poca informació sobre el seu destí ambiental en sòls tropicals. La transformació de residus agroindustrials en biocarbó (biochar) mitjançant piròlisi i la seva adició al sòl com a esmena han estat proposats com una pràctica útil per a la gestió de residus que permet la millora de la qualitat del sòl, el segrestament de carboni i una possible mitigació de la mobilitat de plaguicides. L'objectiu de la tesi fou avaluar els beneficis i eventuals efectes no desitjats de l'adició de biocarbó a un sòl costa-riqueny cultivat amb pinya en combinació amb bromacil o diuron, considerant tant els seus efectes en el destí i eficiència com els ecotoxicològics. Els materials carbonitzats (MC) s'obtingueren per piròlisi a 300 o 600 ºC durant una hora, utilitzant com a materials de partida rostoll de pinya tropical (PS), ""pinzote"" de palmera d'oli (PF) i l'endocarp del fruit de café (cascarilla) (CH), que es van caracteritzar fisicoquímicament i es van aplicar al sòl a dosis d'aplicació de 10 i 20 t ha-1. S'avaluà la sorció, la degradació i la biodegradació dels plaguicides en condicions de laboratori, permetent la predicció del seu risc ambiental amb l'índex de classificació d'impacte de plaguicides. Addicionalment, es van avaluar efectes en l'emergència i creixement de d'enciam (Lactuca sativa), el desenvolupament d'invertebrats (el col·lèmbol Folsomia candid i l'enquitreid Enchytraeus crypticus) i la diversitat funcional de la comunitat dels microorganisms (MicrorespTM) per a provar possibles efectes dels MC en l'eficiència dels herbicides i en organismes terrestres no diana. Els MC a 300 ºC es classificaren com a materials torrefactes (MT) i a 600 ºC com a biocarbons (B). Els biocarbons presentaren major superfície específica, contingut de carboni fixe i pH que els MT, alhora que els PS-B i PF-B tenien major abundància de grups oxigenats superficials que CH-B i que tots els MT. Es va demostrar una sorció dèbil al sòl en tots dos plaguicides, fet que suggereix una elevada mobilitat, i la degradació i biodegradació del bromacil fou limitada en comparació al diruon. L'adició de biocarbó incrementà la persistència del bromacil, i els PS-MT i PF-MT la sorció del diuron. No obstant, això no va canviar la mobilitat i toxicitat aquàtica predites pels pesticides. L'adició de MC no reduí l'eficiència dels herbicides, però augmentà l'emergència sense incrementar el creixement. L'aplicació d'herbicides no causà efectes tòxics en col·lèmbols o enquitreids, sinó que promogué la reproducció sense afectar la supervivència. S'observà una evitació generalitzada de les barreges sòl-MC en enquitreids contrària a la preferència dominant en col·lèmbols, independentment de la presència d'herbicides. Finalment, no aparegueren canvis en la diversitat funcional microbiana amb l'adició d'herbicides o MC, llevat de l'increment en la taxa de consum d'alguns substrats en algunes barreges sòl-MC tractades amb diuron. En conclusió, l'adició de MC no canvià l'eficiència dels herbicides ni el seu destí en l'Ultisol tropical argilós estudiat. Sota la gestió habitual del cultiu de la pinya a la regió nord de Costa Rica, tots dos herbicides presentaren un elevat risc ambiental per a aigües superficials i subterrànies, i malgrat que l'adició de MC no ho va mitigar, no van causar efectes negatius sinó una millora del sòl com a hàbitat per a invertebrats edàfics.La producción de piña es una actividad económica importante en Costa Rica que ha aumentado significativamente su área cultivada en las dos últimas décadas, con una alta generación de residuos agroindustriales y un uso intensivo de plaguicidas, incluidos los herbicidas bromacil y diurón. Ambos se han detectado en aguas superficiales y subterráneas, lo que ha causado problemas ambientales, de salud y económicos, aunque aún existe poca información sobre su destino ambiental en los suelos tropicales. La transformación de residuos agroindustriales en biocarbón (biochar) mediante pirólisis y su adición al suelo como enmienda, se ha propuesto como una práctica útil de gestión de residuos capaz de mejorar la calidad del suelo, el secuestro de carbono y que podría mitigar la movilidad de los plaguicidas. El objetivo de la tesis fue evaluar los beneficios y eventuales efectos no deseados de la adición de biocarbón a un suelo costarricense cultivado con piña en combinación con bromacil o diuron, considerando tanto sus efectos ecotoxicológicos como en su destino y eficiencia. Los materiales carbonizados (MC) se obtuvieron pirolizando a 300 o 600 °C durante una hora rastrojo de piña (PS), pinzote de palma aceitera (PF) y cascarilla de café (CH), se caracterizaron física y químicamente y se mezclaron con suelo en dosis de aplicación equivalentes a 10 y 20 t ha-1. Se evaluaron la sorción, la degradación y la biodegradación de ambos plaguicidas en condiciones de laboratorio con lo que se predijo su riesgo ambiental con el Índice de Clasificación de Impacto de Plaguicidas. Además, se midió la emergencia y el crecimiento de la lechuga (Lactuca sativa), el desarrollo de invertebrados (colémbolo Folsomia candida; enquitréido Enchytraeus crypticus) y la diversidad funcional de los microorganismos (Microresp™) para probar los efectos de los MC en la eficiencia de los herbicidas y sobre organismos terrestres no diana. Los MC a 300 °C se clasificaron como materiales torrefactos (MT) y a 600 °C como biocarbones (B). Los biocarbones mostraron mayor superficie específica, contenido de carbono fijo y pH que los MT, mientras que los PS-B y PF-B presentaron mayor abundancia de grupos funcionales oxigenados superficiales que el CH-B y que todos los MT. Se observó una sorción débil de ambos plaguicidas en el suelo, lo que sugiere una alta movilidad, mientras que la degradación y biodegradación de bromacil fue limitada comparada con el diurón. La adición de biocarbón aumentó la persistencia del bromacil, mientras que los PS-MT y PF-MT aumentaron la sorción del diurón. No obstante, la movilidad y la toxicidad acuática predichas de los herbicidas no se afectaron. La adición de MC no redujo la eficiencia de los herbicidas, pero aumentó la emergencia sin mejorar el crecimiento. La aplicación de herbicidas no tuvo efectos tóxicos sobre colémbolos o enquitréidos pues promovió su reproducción sin afectar la supervivencia. Hubo una evitación generalizada de los enquitréidos de las mezclas suelo-MC opuesta a la preferencia general de los colémbolos, independientemente de la presencia de herbicidas. Finalmente, no se demostraron cambios en la diversidad funcional microbiana por la adición de herbicidas o MC, y solo se observó un aumento en la tasa de consumo de algunos sustratos en algunas mezclas suelo-MC tratados con diurón. En conclusión, la adición de MC no cambió la eficiencia de los herbicidas ni su destino en el Ultisol tropical arcilloso estudiado. Bajo la gestión habitual del cultivo de la piña en la Región Norte de Costa Rica, ambos herbicidas presentaron un elevado riesgo ambiental para aguas superficiales y subterráneas, y pese a que la adición de MC no le mitigar, no causaron efectos negativos sino una mejora del suelo como hábitat para invertebrados edáficos.Pineapple production is an important economic activity in Costa Rica as shown by the increase in its cropped area in the last two decades. It involves a high generation of agro-wastes as well as an intensive application of pesticides, including the herbicides bromacil, and diuron. Their use is associated with problems of environmental, health and economic concern, because it has been detected in both surface water and groundwater. However, there is still scarce information about the environmental fate of these herbicides in tropical soils. The transformation of this agro-waste surplus by pyrolysis into biochar, a carbonaceous material, followed by its addition to soil as an amendment, has been suggested as a useful waste management practice. This is because it may improve the soil quality and carbon sequestration and potentially mitigate the mobility of pesticides. The aim of this thesis was to evaluate the benefits and unexpected effects of biochar addition to a Costa Rican agricultural soil cropped to pineapple, concurrently considering the effects on bromacil and diuron fate and efficiency as well as non-target soil ecotoxicological effects. For this purpose, pineapple stubble (PS), oil palm fiber (PF) and coffee hulls (CH) were pyrolyzed at 300 or 600 °C for one hour and then physically and chemically characterized. Mixtures of the charred materials (CM) with soil were prepared at application rates equivalent to 10 and 20 t ha-1. Sorption, degradation, and biodegradation of both pesticides were evaluated in the laboratory, and the results were used to predict their environmental risk with the Pesticide Impact Rating Index. In addition, lettuce emergence and growth (Lactuca sativa), invertebrates performance (collembolan Folsomia candida; enchytraeid Enchytraeus crypticus), and microorganism functional diversity (Microresp™) were used to test the effects of CM on the herbicides' efficiency and on the non-target soil biological groups. CM pyrolyzed at 300 °C were classified as torrefied materials (TM), while those pyrolized at 600 °C were classified as biochars (B). Biochars showed higher specific surface area, fixed carbon content and pH values than TM, while PS-B and PF-B presented a higher abundance of surface oxygenated chemical groups than CH-B and all the TM. A weak sorption of both herbicides to soil was observed suggesting a high mobility, while the degradation and biodegradation of bromacil was more limited compared to that of diuron. The addition of biochars increased the persistence of bromacil, while PS-TM and PF-TM increased the sorption of diuron. Despite that, the predicted mobility and aquatic toxicity of the herbicides were unaffected. The addition of CM did not reduce herbicide efficiency but increased seedling emergence without improving growth. The adding of herbicides had no toxic effects on collembolans and enchytraeids as it promoted their reproduction without affecting survival. A generalized avoidance of CM-mixtures by enchytraeids was observed as opposed to the general preference shown in collembolans, irrespective of the supplementation or not of herbicides. Finally, no changes in the microbial functional diversity by the sole addition of herbicides or CM were demonstrated, and a significant increase in the consumption rate of some substrates was observed only in some diuron-treated CM-mixtures. In summary, the addition of CM did not change the efficiency of the herbicides nor their fate in a tropical clay Ultisol. Under pineapple cropping conditions of the northern region of Costa Rica, bromacil and diuron presented a high estimated environmental risk to surface water and groundwater, and the addition of CM did not change this risk. Simultaneously, no negative effects to the soil ecosystem were observed, but there was an improvement in soil as a habitat for some soil invertebrates

Adaptation of biomixtures for the accelerated degradation of carbofuran in a tropical environment

One of the main causes of agroindustrial origen contamination is the spillage and disposal of pesticides, especially during the loading, mixing or cleaning of agricultural spraying equipments. Thus, appropriate management and treatment of these chemicals are necessary practices. One improvement in the handling of organic pollutants is the use of biopurification systems (biobeds), simple and cheap degradation systems where the pesticides are biologically degraded at accelerated rates (Castillo et al., 2008). However, design of biobeds or other biodegradation systems is dependent on regional characteristics, particularly climatic conditions and the materials/residues available for their construction, particularly the components of the biomixture, active core of the biobed (Karanasios et al., 2012). The present work aimed at screening the efficiency of several biomixtures made with waste materials from Costa Rican agricultural industry to degrade the insectice/nematicide carbofuran, in terms of removal of degradation and reduction in toxicity. A lignocellulosic substrate (rice husk, wood chips, coconut fiber, sugarcane bagasse or newspaper print), and a humic-rich material (peat or garden compost) were mixed with soil pre-exposed to carbofuran (CBF), in order to obtain ten different biomixtures. After spiking with 50 mg/kg CBF, the efficiency of the biomixture was evaluated through a multi-component approach that included: monitoring of CBF removal and production of CBF transformation products (3-hydroxycarbofuran and 3-ketocarbofuran), mineralization of radioisotopically labeled carbofuran (14C-CBF) and changes in the toxicity of the matrix after the treatment (Daphnia magna acute immobilization test). Estimated half-lives of CBF in the biomixtures ranged from 2.5 d to 10.3 d, with six out of ten mixtures showing values below 5 d. After 16 d, removal >98.5% was achieved for eight biomixtures. The best performance was exhibited by the biomixture composed of coconut fiber-compost-soil (FCS), with a half-life of 2.5 d and 79.6% elimination in 4 d. Transformation products were detected in every case at concentrations below quantification limit. Mineralization of CBF was monitored over a 63 d period. Highest mineralization rates were achieved for the mixtures composed of FCS, bagasse-compost-soil (BCS) and newspaper-peat-soil (PTS), in every case above the mineralization rate obtained in solely the pre-exposed soil (>12%). Toxicity of the biomixtures was determined after the treatment period. Initial toxicity of the matrix (after spiking the CBF solution) that was as high as 200 toxicity units (TU), was reduced to <2 TU after 63 d in every biomixture (0 TU in eight cases). Residual toxicity was detected only in peat containing biomixtures. In general, compost-based biomixtures seem more efficient in the process of removal CBF, than peat-based biomixtures. This is a remarkable finding, as peat is more difficult to find and is therefore more expensive than compost in tropical lands. The facts that removal of the parent compound is almost complete in only 16 d, production of major transformation products is negligible and toxicity is markedly reduced/eliminated in the process, make the evaluated biomixtures potential candidates for the eco-friendly degradation of CBF in biobeds. Despite the general good performance of the biomixtures, the authors remark the biomixture FCS as the strongest candidate for use in biopurification systems for the treatment of CBF containing wastewaters, as it uses compost, showed the faster elimination of CFN, low production of transformation products, high mineralization rate and complete elimination of toxicity. References: Castillo MP, Torstensson L & Stenström J (2008) Biobeds for environmental protection from pesticide use – A review. J. Agric Food Chem 56: 6206-6219. Karanasios E, Tsiropoulos NG & Karpouzas DG (2012) On-farm biopurification systems for the depuration of pesticide wastewaters: recent biotechnological advances and future perspectives. Biodegradation 23: 787-802

Adaptation of biomixtures for the accelerated degradation of carbofuran in a tropical environment

One of the main causes of agroindustrial origen contamination is the spillage and disposal of pesticides, especially during the loading, mixing or cleaning of agricultural spraying equipments. Thus, appropriate management and treatment of these chemicals are necessary practices. One improvement in the handling of organic pollutants is the use of biopurification systems (biobeds), simple and cheap degradation systems where the pesticides are biologically degraded at accelerated rates (Castillo et al., 2008). However, design of biobeds or other biodegradation systems is dependent on regional characteristics, particularly climatic conditions and the materials/residues available for their construction, particularly the components of the biomixture, active core of the biobed (Karanasios et al., 2012). The present work aimed at screening the efficiency of several biomixtures made with waste materials from Costa Rican agricultural industry to degrade the insectice/nematicide carbofuran, in terms of removal of degradation and reduction in toxicity. A lignocellulosic substrate (rice husk, wood chips, coconut fiber, sugarcane bagasse or newspaper print), and a humic-rich material (peat or garden compost) were mixed with soil pre-exposed to carbofuran (CBF), in order to obtain ten different biomixtures. After spiking with 50 mg/kg CBF, the efficiency of the biomixture was evaluated through a multi-component approach that included: monitoring of CBF removal and production of CBF transformation products (3-hydroxycarbofuran and 3-ketocarbofuran), mineralization of radioisotopically labeled carbofuran (14C-CBF) and changes in the toxicity of the matrix after the treatment (Daphnia magna acute immobilization test). Estimated half-lives of CBF in the biomixtures ranged from 2.5 d to 10.3 d, with six out of ten mixtures showing values below 5 d. After 16 d, removal >98.5% was achieved for eight biomixtures. The best performance was exhibited by the biomixture composed of coconut fiber-compost-soil (FCS), with a half-life of 2.5 d and 79.6% elimination in 4 d. Transformation products were detected in every case at concentrations below quantification limit. Mineralization of CBF was monitored over a 63 d period. Highest mineralization rates were achieved for the mixtures composed of FCS, bagasse-compost-soil (BCS) and newspaper-peat-soil (PTS), in every case above the mineralization rate obtained in solely the pre-exposed soil (>12%). Toxicity of the biomixtures was determined after the treatment period. Initial toxicity of the matrix (after spiking the CBF solution) that was as high as 200 toxicity units (TU), was reduced to <2 TU after 63 d in every biomixture (0 TU in eight cases). Residual toxicity was detected only in peat containing biomixtures. In general, compost-based biomixtures seem more efficient in the process of removal CBF, than peat-based biomixtures. This is a remarkable finding, as peat is more difficult to find and is therefore more expensive than compost in tropical lands. The facts that removal of the parent compound is almost complete in only 16 d, production of major transformation products is negligible and toxicity is markedly reduced/eliminated in the process, make the evaluated biomixtures potential candidates for the eco-friendly degradation of CBF in biobeds. Despite the general good performance of the biomixtures, the authors remark the biomixture FCS as the strongest candidate for use in biopurification systems for the treatment of CBF containing wastewaters, as it uses compost, showed the faster elimination of CFN, low production of transformation products, high mineralization rate and complete elimination of toxicity. References: Castillo MP, Torstensson L & Stenström J (2008) Biobeds for environmental protection from pesticide use – A review. J. Agric Food Chem 56: 6206-6219. Karanasios E, Tsiropoulos NG & Karpouzas DG (2012) On-farm biopurification systems for the depuration of pesticide wastewaters: recent biotechnological advances and future perspectives. Biodegradation 23: 787-802

Adaptation of biomixtures for the accelerated degradation of carbofuran in a tropical environment

One of the main causes of agroindustrial origen contamination is the spillage and disposal of pesticides, especially during the loading, mixing or cleaning of agricultural spraying equipments. Thus, appropriate management and treatment of these chemicals are necessary practices. One improvement in the handling of organic pollutants is the use of biopurification systems (biobeds), simple and cheap degradation systems where the pesticides are biologically degraded at accelerated rates (Castillo et al., 2008). However, design of biobeds or other biodegradation systems is dependent on regional characteristics, particularly climatic conditions and the materials/residues available for their construction, particularly the components of the biomixture, active core of the biobed (Karanasios et al., 2012). The present work aimed at screening the efficiency of several biomixtures made with waste materials from Costa Rican agricultural industry to degrade the insectice/nematicide carbofuran, in terms of removal of degradation and reduction in toxicity. A lignocellulosic substrate (rice husk, wood chips, coconut fiber, sugarcane bagasse or newspaper print), and a humic-rich material (peat or garden compost) were mixed with soil pre-exposed to carbofuran (CBF), in order to obtain ten different biomixtures. After spiking with 50 mg/kg CBF, the efficiency of the biomixture was evaluated through a multi-component approach that included: monitoring of CBF removal and production of CBF transformation products (3-hydroxycarbofuran and 3-ketocarbofuran), mineralization of radioisotopically labeled carbofuran (14C-CBF) and changes in the toxicity of the matrix after the treatment (Daphnia magna acute immobilization test). Estimated half-lives of CBF in the biomixtures ranged from 2.5 d to 10.3 d, with six out of ten mixtures showing values below 5 d. After 16 d, removal >98.5% was achieved for eight biomixtures. The best performance was exhibited by the biomixture composed of coconut fiber-compost-soil (FCS), with a half-life of 2.5 d and 79.6% elimination in 4 d. Transformation products were detected in every case at concentrations below quantification limit. Mineralization of CBF was monitored over a 63 d period. Highest mineralization rates were achieved for the mixtures composed of FCS, bagasse-compost-soil (BCS) and newspaper-peat-soil (PTS), in every case above the mineralization rate obtained in solely the pre-exposed soil (>12%). Toxicity of the biomixtures was determined after the treatment period. Initial toxicity of the matrix (after spiking the CBF solution) that was as high as 200 toxicity units (TU), was reduced to <2 TU after 63 d in every biomixture (0 TU in eight cases). Residual toxicity was detected only in peat containing biomixtures. In general, compost-based biomixtures seem more efficient in the process of removal CBF, than peat-based biomixtures. This is a remarkable finding, as peat is more difficult to find and is therefore more expensive than compost in tropical lands. The facts that removal of the parent compound is almost complete in only 16 d, production of major transformation products is negligible and toxicity is markedly reduced/eliminated in the process, make the evaluated biomixtures potential candidates for the eco-friendly degradation of CBF in biobeds. Despite the general good performance of the biomixtures, the authors remark the biomixture FCS as the strongest candidate for use in biopurification systems for the treatment of CBF containing wastewaters, as it uses compost, showed the faster elimination of CFN, low production of transformation products, high mineralization rate and complete elimination of toxicity. References: Castillo MP, Torstensson L & Stenström J (2008) Biobeds for environmental protection from pesticide use – A review. J. Agric Food Chem 56: 6206-6219. Karanasios E, Tsiropoulos NG & Karpouzas DG (2012) On-farm biopurification systems for the depuration of pesticide wastewaters: recent biotechnological advances and future perspectives. Biodegradation 23: 787-802

Accelerated biodegradation of selected nematicides in tropical crop soils from Costa Rica

Degradation and mineralization behavior of select ed nematicides was studied in soil samples from fields culti vated with banana, potato, and coffee. Degradation assays in most of the studied soils revealed shorter half-lives for carbofuran (CBF) and ethoprophos (ETP) in samples with a history of treatment with these compounds, which may have been caused by enhanced biodegradation. A short half-life value for CBF degradation was also observed in a banana field with no previous exposure to this pesticide, but with a recent application of the carbamate insecticide oxamyl, which supports the hypothesis that preexposure to oxamyl may cause microbial adaptation towards degradation of CBF, an obser vation of a phenomenon not yet tested according to the liter ature reviewed. Mineralization assays for CBF and terbufos (TBF) revealed that history of treatment with these nemati cides did not cause higher mineralization rates in preexposed soils when compared to unexposed ones, except in the case of soils from coffee fields. Mineralization half-lives for soils unexposed to these pesticides were significantly shorter than most reports in the literature in the same conditions. Mineralization rates for soils with a previous exposure to these pesticides were also obtained, adding to the very few reports found. This paper contributes valuable data to the low number of reports dealing with pesticide fate in soils from tropical origin.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro en Investigación en Contaminación Ambiental (CICA)UCR::Vicerrectoría de Docencia::Salud::Facultad de Microbiologí

Effects of oxytetracycline on the performance and activity of biomixtures: Removal of herbicides and mineralization of chlorpyrifos

Biopurification systems (BPS) are design to remove pesticides from agricultural wastewater. This work assays for the first time the potential effect of an antibiotic of agricultural use (oxytetracycline, OTC) on the performance of a biomixture (biologically active core of BPS), considering that antibiotic-containing wastewaters are also produced in agricultural labors. The respiration of the biomixture was stimulated in the presence of increasing doses of OTC (≥100 mg kg−1), and only slightly increased with lower doses (≤10 mg kg−1). When co-applied during the removal of chlorpyrifos, OTC increased chlorpyrifos mineralization rates at low doses, resembling a hormetic effect. The biomixture was also able to remove three herbicides (atrazine, ametryn and linuron) with half-lives of 24.3 d, 43.9 d and 30.7 d; during co-application of OTC at a biomixture-relevant concentration, only the removal of ametryn was significantly inhibited, increasing its half-life to 92.4 d. Ecotoxicological assays revealed that detoxification takes place in the biomixture during the removal of herbicides in the presence of OTC. Overall results suggest that co-application of OTC in a biomixture does not negatively affect the performance of the matrix in every case; moreover, the co-application of this antibiotic could improve the mineralization of some pesticides.Universidad de Costa Rica/[802-B4-503]/UCR/Costa RicaUniversidad de Costa Rica/[802-B6-137]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro en Investigación en Contaminación Ambiental (CICA

Removal of carbamates and detoxification potential in a biomixture: Fungal bioaugmentation versus traditional use

The use of fungal bioaugmentation represents a promising way to improve the performance of biomixtures for the elimination of pesticides. The ligninolyitc fungus Trametes versicolor was employed for the removal of three carbamates (aldicarb, ALD; methomyl, MTM; and methiocarb, MTC) in defined liquid medium; in this matrix ALD and MTM showed similar half-lives (14 d), nonetheless MTC exhibited a faster removal, with a half-life of 6.5 d. Then the fungus was employed in the bioaugmentation of an optimized biomixture to remove the aforementioned carbamates plus carbofuran (CFN). Bioaugmented and non-bioaugmented systems removed over 99% ALD and MTM after 8 d of treatment, nonetheless a slight initial delay in the removal was observed in the bioaugmented biomixtures (removal after 3 d: ALD 87%/97%; MTM 86%/99%, in bioaugmented/non-bioaugmented systems). The elimination of the other carbamates was slower, but independent of the presence of the fungus: >98% for MTM after 35 d and >99.5% for CFN after 22 d. Though the bioaugmentation did not improve the removal capacity of the biomixture, it favored a lower production of transformation products at the first stages of the treatment, and in both cases, a marked decrease in the toxicity of the matrix was swiftly achieved along the process (from 435 to 448 TU to values <1TU in 16 d).Universidad de Costa Rica/[802-B4-503]/UCR/Costa RicaUniversidad de Costa Rica/[802-B4-609]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro en Investigación en Contaminación Ambiental (CICA