Modelos de regresión non lineais con erros nos regresores: unha aplicación á xestión de recursos pesqueiros

Analízase o xeito no que se estiman modelos de regresión non lineais que se utilizan na xestión de recursos pesqueiros. O obxectivo é demostrar as consecuencias de descoidar a posibilidade de que os regresores deses modelos, poidan estar medidas con erros aditivos

Distribuição do mercúrio total em função da dimensão dos agregados num podzol de floresta temperada

This study determined the distribution of total Hg (HgT) among aggregate size fractions in the A, E, Bh and Bs horizons of a representative temperate forest podzol. The aggregate distribution was dominated by the coarse sand size fraction (average of 55%) followed by fine sand (29%), fine silt (10%), coarse silt (4%) and clay (2%). In general, HgT mean values increased as the aggregate size become smaller: clay (170 ng g-1) > fine silt (130 ng g-1) > coarse silt (80 ng g-1) > fine sand (32 ng g-1) > coarse sand (14 ng g-1). Total Hg enrichment in clay-sized aggregates ranged from 2 to 11 times higher than the values shown by the bulk soil ( 50% of HgT in Bh and Bs horizons. The potential ecological risk index (PERIHg) increased as the aggregate size decreased, with the highest values in the illuvial horizons (45-903) and lowest in the E horizon (3-363). Heterogeneous distribution of Hg in the soil aggregate size fractions must be considered for Hg determination for purposes such as critical loads, background values or environmental risk indices. In addition, Hg accumulation in finer aggregates could be of concern due to its potential mobility in forest soils, either transferred by leaching to groundwater and freshwaters or mobilized by runoff in surface horizons.En este trabajo se analiza la distribución de Hg total (HgT) en fracciones de tamaño agregado en los horizontes A, E, Bh y Bs de un podzol forestal representativo. La distribución de agregados fue dominada por la fracción de tamaño arena gruesa (promedio del 55%), seguida arena fina (29%), limo fino (10%), limo grueso (4%) y arcilla (2%). En general, los valores medios de HgT incrementaron a medida que el tamaño de los agregados disminuía: arcilla (170 ng g-1) > limo fino (130 ng g-1) > limo grueso (80 ng g-1) > arena fina (32 ng g-1) > arena gruesa (14 ng g-1). El enriquecimiento de HgT en los agregados de tamaño arcilla varía entre 2 y 11 veces más que los niveles en la fracción tierra fina (< 2 mm). La acumulación de HgT en los agregados de menor tamaño estaba estrechamente asociada al C orgánico total, al C extraído con pirofosfato Na, a los complejos metal (Al, Fe)-humus y a los oxihidróxidos de Fe y Al. De hecho, estos parámetros variaron significativamente (p < 0,05) con el tamaño de agregado y sus valores más elevados se encontraron en las fracciones más finas. Esto sugiere el papel de estos compuestos del suelo en el incremento de la superficie específica por unidad de masa y de cargas negativas en los agregados más pequeños, favoreciendo la retención de Hg. Los valores del factor de acumulación de Hg (HgAF) fueron de hasta 10,8 en los agregados de tamaño arcilla, siendo cercanos a 1 en las fracciones de tamaño arena. Respecto de los factores de enriquecimiento de Hg (HgEF), estos fueron < 4 (categoría “contaminación moderada”) en la mayoría de los horizontes y tamaños de agregado. El índice de masa por tamaño de agregado (GSFHg) reveló que las fracciones más finas tenían una mayor carga de Hg que el correspondiente a sus masas, siendo destacable la contribución del limo fino que constituía más del 50% del HgT en los horizontes Bh y Bs. El índice de riesgo ecológico potencial (PERIHg) aumentó conforme disminuía el tamaño de agregado, con los valores más altos en los horizontes iluviales (45-903) y los más bajos en el horizonte E (3-363). La distribución heterogénea del Hg entre fracciones de tamaño agregado debe ser tenida en cuenta para la determinación de Hg para fines como cargas críticas, valores de fondo geoquímico o índices de riesgos medioambientales. Además, la acumulación de Hg en los agregados más finos podría ser preocupante debido a su potencial movilidad en suelos forestales, tanto mediante su transferencia por lixiviado a aguas freáticas y superficiales como su movilización por escorrentía en los horizontes superficiales.Neste estudo determinou-se a distribuição do Hg total (HgT) pelos agregado de diferentes frações nos horizontes A, E, Bh e Bs de um podzol representativo de floresta temperada. A distribuição dos agregados foi dominada pela fração areia grossa (média de 55%) seguida de areia fina (29%), limo fino (10%), limo grosseiro (4%) e argila (2%). Em geral, os valores médios da HgT aumentaram à medida que a dimensão do agregado diminuiu: argila (170 ng g-1) > limo fino (130 ng g-1) > limo grosseiro (80 ng g-1) > areia fina (32 ng g-1) > areia grosseira (14 ng g-1). O enriquecimento total de Hg em agregados da dimensão argila variou, sendo de 2 a 11 vezes maior do que os valores na fração terra fina (< 2 mm). A acumulação de HgT em agregados de menor dimensão estava intimamente relacionada com o C orgânico total, C extraído com pirofosfato de Na, aos complexos organo-metálicos (Al, Fe) e aos oxihidróxidos de Fe e Al. De facto, esses parâmetros variaram significativamente (p < 0,05) com o tamanho do agregado e os valores mais altos ocorreram nas frações mais finas. Isto sugere o papel destes compostos do solo no aumento da superfície específica e das cargas negativas nos agregados de menor dimensão, favorecendo a retenção do Hg. Os valores do fator de acumulação de Hg (HgAF) atingiram o valor de 10,8 nos agregados da dimensão argila, sendo próximos da unidade nas frações areia. Os fatores de enriquecimento do Hg (HgEF) apresentam valores < 4 (categoria "poluição moderada") na maioria dos horizontes e dimensão de agregados. O índice de massa por dimensão de agregado (GSFHg) revelou que as frações mais finas apresentam maior carga de Hg do que as suas frações de massa, sendo notável a contribuição do limo fino ao qual correspondiam valores > 50% de HgT nos horizontes Bh e Bs. O índice de risco ecológico potencial (PERIHg) aumentou com a diminuição do tamanho do agregado, com os valores mais altos nos horizontes iluviais (45-903) e mais baixos no horizonte E (3-363). A distribuição heterogénea de Hg nos agregados de várias dimensões deve ser considerada para determinação do Hg no solo com objetivos tais como cargas críticas, valores de fundo ou índices de risco ambiental. Além disso, a acumulação de Hg em agregados mais finos pode ser motivo de preocupação devido à sua potencial mobilidade em solos florestais, quer pela sua transferência por lixiviação para as águas subterrâneas e superficiais, quer por mobilização por escoamento superficial desorganizado em horizontes superficiais.This work was supported by the Consellería de Cultura, Educación e Ordenación Universitaria (Xunta de Galicia) with a Reference Competitive Groups grant (ED431C2017/62) to BV1 Research Group. Xunta de Galicia is acknowledged by the pre-doctoral fellowship of A. G. A. (ED481A-2016/220)S

Controlling risks of P water pollution by sorption on soils, pyritic material, granitic material, and different by-products: effects of pH and incubation time

This version of the article has been accepted for publication, after peer review and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1007/s11356-018-2267-9Batch 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.Ministerio de Economía y Competitividad (Government of Spain) e European Regional Development Fund (ERDF) (FEDERin Spain)S

Occurrence of tetracyclines and sulfonamides in manures, agricultural soils and crops from different areas in Galicia (NW Spain)

Antibiotics released to the environment are causing public health and sustainability concerns. Taking that into account, we studied the presence of tetracyclines (Tetracycline, Oxytetracycline, Chlortetracycline and Doxycycline) and sulfonamides (Sulfadiazine, Sulfamethazine, Sulfachlorpyridazine and Sulfamethoxypyridazine) in manures, soils and crops from Galicia (Spain), where a high number of cattle, pig and poultry farms exist. We used the HPLC-MS/MS technique to analyze 40 samples of cattle, pig and poultry manure, as well as 65 soil samples, and 27 vegetation samples. The presence of antibiotics was detected in 42% of the manures, 17% of the soils and 44% of crop samples, with maximum concentrations of 106.0 mg kg−1 for individual antibiotics in manures and 0.6 mg kg−1 in soils and plants. The simultaneous presence of several antibiotics was infrequent in soils (only three soils presented two or three antibiotics), and more common in manures and plants, some of them with up to five antibiotics. Pig slurries showed the highest antibiotic concentrations, as well as the highest number of different antibiotics. Crops fertilized with these slurries also showed the highest number of different antibiotics. Antibiotics were detected in 71% of grass and corn samples, and in 33% of wheat grain samples, while they were not detected in potato samples. These results can be very relevant taking into account potential environmental and public health repercussions of antibiotics in soil and water, as well as antibiotics uptake and accumulation in plants, and subsequent incorporation to the food chain.This work was supported by the Spanish Ministry of Economy and Competitiveness [grant numbers CGL2015-67333-C2-1-R and CGL2015-67333-C2-2-R]. M. Conde-Cid holds a pre-doctoral contract (FPU15/0280, Spanish Government). The sponsor had not involvement in study design; in the collection, analysis and interpretation of data; in the writing of the report, and in the decision to submit the article for publication.S

Cr(VI) sorption/desorption on untreated and mussel-shell-treated soil materials: fractionation and effects of pH and chromium concentration

We used batch-type experiments to study Cr(VI) sorption/desorption on granitic material, forest soil, pyritic material, mussel shell, and on forest soil and granitic material amended with 12 t ha−1 (1.2 kg m −2) shell, considering the effects of varying Cr(VI) concentration and pH. Sequential extractions were carried out to fractionate adsorbed Cr(VI) and to determine the stability of Cr(VI) retention. The pyritic material had the highest Cr(VI) retention capacity, whereas the granitic material showed the lowest retention potential. When high Cr concentrations were added, some saturation of the adsorbent surfaces became apparent, but Cr release remained low. The highest Cr retention was achieved at a very acid pH value, with release progressively increasing as a function of increasing pH. The amendment with 12 t ha−1 mussel shell did not cause marked changes in Cr(VI) retention. Sorption data were satisfactory adjusted to the Freundlich model. Regarding Cr(VI) fractionation, the soluble fraction (weakly bound) was dominant in mussel shell and in the unamended and amended granitic material, whereas more stable fractions dominated in the pyritic material (residual fraction) and in the forest soil (oxidizable fraction). In conclusion, the pyritic material presented the highest Cr(VI) retention capacity, while the retention was low and weak on the granitic material; mussel shell was not characterized by a marked Cr(VI) retention potential, and it did not cause remarkable increase in Cr(VI) retention when used to amend the granitic material or the forest soil.This study was funded by the Ministerio de Economía y Competitividad (Government of Spain), grant numbers CGL2012-36805-C02-01-02S

As(V) sorption/desorption on different waste materials and soil samples

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.Ministerio de Economía y Competitividad | Ref. CGL2012-36805-C02-01Ministerio de Economía y Competitividad | Ref. CGL2012-36805-C02-0

Chromium VI and Fluoride Competitive Adsorption on Different Soils and By-Products

Chromium (as Cr(VI)) and fluoride (F−) are frequently found in effluents from different industrial activities. In cases where these effluents reach soil, it can play an important role in retaining those pollutants. Similarly, different byproducts could act as bio-adsorbents to directly treat polluted waters or to enhance the purging potential of soil. In this work, we used batch-type experiments to study competitive Cr(VI) and F− adsorption in two different soils and several kinds of byproducts. Both soils, as well as mussel shell, oak ash, and hemp waste showed higher adsorption for F−, while pyritic material, pine bark, and sawdust had a higher affinity for Cr(VI). Considering the binary competitive system, a clear competition between both elements in anionic form is shown, with decreases in adsorption of up to 90% for Cr(VI), and of up to 30% for F−. Adsorption results showed better fitting to Freundlich’s than to Langmuir’s model. None of the individual soils or byproducts were able to adsorbing high percentages of both pollutants simultaneously, but it could be highly improved by adding pine bark to increase Cr(VI) adsorption in soils, thus drastically reducing the risks of pollution and deleterious effects on the environment and on public healthThis research was funded by the SPANISH MINISTRY OF ECONOMY AND COMPETITIVENESS by means of the research projects CGL2012-36805-C02-01 and CGL2012-36805-C02-02. It was also partially financed by the European Regional Development Fund (FEDER in Spain)S

Occurrence of tetracyclines and sulfonamides in manures, agricultural soils and crops from different areas in Galicia (NW Spain)

Antibiotics released to the environment are causing public health and sustainability concerns. Taking that into account, we studied the presence of tetracyclines (Tetracycline, Oxytetracycline, Chlortetracycline and Doxycycline) and sulfonamides (Sulfadiazine, Sulfamethazine, Sulfachlorpyridazine and Sulfamethoxypyridazine) in manures, soils and crops from Galicia (Spain), where a high number of cattle, pig and poultry farms exist. We used the HPLC-MS/MS technique to analyze 40 samples of cattle, pig and poultry manure, as well as 65 soil samples, and 27 vegetation samples. The presence of antibiotics was detected in 42% of the manures, 17% of the soils and 44% of crop samples, with maximum concentrations of 106.0 mg kg−1 for individual antibiotics in manures and 0.6 mg kg−1 in soils and plants. The simultaneous presence of several antibiotics was infrequent in soils (only three soils presented two or three antibiotics), and more common in manures and plants, some of them with up to five antibiotics. Pig slurries showed the highest antibiotic concentrations, as well as the highest number of different antibiotics. Crops fertilized with these slurries also showed the highest number of different antibiotics. Antibiotics were detected in 71% of grass and corn samples, and in 33% of wheat grain samples, while they were not detected in potato samples. These results can be very relevant taking into account potential environmental and public health repercussions of antibiotics in soil and water, as well as antibiotics uptake and accumulation in plants, and subsequent incorporation to the food chain.Ministerio de Economía y Competitividad | Ref. CGL2015-67333-C2-1-RMinisterio de Economía y Competitividad | Ref. CGL2015-67333-C2-2-

Metais pesados em solos de pastagem da A Pastoriza (NO Espanha) tratados com chorume de vaca e adubos NPK

In Galicia (NW Spain), pasturelands cover a broad extension and are mainly used to feed cattle. Farms are managed in an intensive manner, using cattle slurry and inorganic fertilizers to increase pasture production, but also increasing risks of heavy metal pollution. In this work we studied the influence of fertilization practices on total concentrations and in-depth distribution of heavy metals and related elements (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn) in two forest soils (SN1, SN2) and five pastureland soils (P1-P5) fertilized with cattle slurry and NPK, in a broadly exploded farmland area (A Pastoriza, Lugo). Soils SN2 and P4 were developed over slate, whereas soils SN1, P1, P2, P3 and P5 evolved on Candana quartzite. Forest soils presented acid pH (4.58-4.68), high Al saturation (75-90%), and low available P concentration (4.78-11.96 mg kg-1), whereas those parameters exhibited better scores in the pastureland soils, due to previous amendment and fertilization practices, thus giving pH 5.17-7.02, Al saturation 0.58-59.24%, and available P 5.24-42.07 mg kg-1. Regarding heavy metals, soil depth did not affect significantly to total concentrations, contrary to that happening with parent material, with higher As, Cu, Fe, and Ni concentrations found in soils over slate (possibly due to the presence of pyritic materials). In most cases, heavy metal total concentrations were lower than that considered as reference background levels for soils developed over each of the parent materials, and were always lower than that considered phyto-toxic. In this study, natural soils usually presented heavy metal total contents similar or even higher than that of the fertilized soils (unless Zn in the P4 pastureland), thus indicating that the spread doses of fertilizers did not influence significantly their concentration levels.En Galicia las praderas ocupan una gran extensión, siendo utilizadas principalmente para la alimentación del ganado vacuno destinado tanto a la producción de leche como de carne. Las granjas se manejan de manera intensiva, utilizando fertilizantes inorgánicos y purín de vacuno para aumentar la producción de pastos. Esta práctica puede aumentar el contenido de metales pesados en el suelo. En este trabajo se estudian las concentraciones totales y la distribución en profundidad de metales pesados y elementos afines (As, Cd, Cr, Cu, Mn, Ni, Pb y Zn) en dos suelos forestales (SN1, SN2) y en cinco praderas (P1-P5) fertilizadas con purín de vacuno y NPK en una zona con una gran vocación ganadera (A Pastoriza, Lugo). Se pretende conocer el grado de influencia de la fertilización sobre los niveles de estos elementos. Los suelos elegidos se desarrollaron a partir de pizarras (SN2, P4) y de cuarcitas de la Serie de Cándana (SN1, P1, P2, P3, P5). Los suelos forestales presentaron pH ácido (4,58-4,68), elevada saturación del complejo de cambio por Al (75-90%) y baja concentración de P disponible (4,78-11,96 mg kg-1); estos parámetros mejoran en los suelos de pradera como consecuencia de las enmiendas y fertilizantes aplicados, presentando un pH entre 5,17 y 7,02, una saturación de Al que varía entre 0,58-59,24% y P disponible entre 5,24 y 42,07 mg kg-1. En relación con los metales pesados, la profundidad de la muestra no afecta de modo significativo a su concentración total, pero sí el material de partida, presentando concentraciones más elevadas de Fe, As, Cu y Ni los suelos desarrollados sobre pizarras, posiblemente debido a la presencia de materiales piríticos. En la mayoría de los casos, los metales pesados estudiados presentan concentraciones totales inferiores a las establecidas como genéricas para suelos desarrollados sobre los respectivos materiales geológicos, y siempre son menores que los límites considerados fitotóxicos. La fertilización aplicada no parece tener una influencia significativa sobre los contenidos totales de estos elementos, con la excepción del Zn en la pradera P4, ya que los suelos naturales en muchos casos presentan valores similares e incluso superiores a los obtenidos en las parcelas fertilizadas.As pastagens ocupam uma grande área na região da Galicia (NO Espanha) destnando-se sobretudo à alimentação de bovinos para produção de leite e carne. As explorações são geridas de forma intensiva, aplicando-se adubos minerais e chorumes com o objetivo de aumentar a produção de pastos. Contudo, esta prática pode aumentar o teor de metais pesados no solo. Neste trabalho, a concentração total e a distribuição em profundidade de metais pesados e elementos associados (As, Cd, Cr, Cu, Mn, Ni, Pb e Zn) foram estudados em dois solos florestais (SN1, SN2) em cinco talhões (P1-P5) adubados com NPK e chorume de bovino, numa área com uma grande vocação para pecuária (A Pastoriza, Lugo). Teve-se por objetivo principal determinar o grau de influência da fertilização nos teores destes elementos. Os solos selecionados foram desenvolvidos a partir de ardósias (SN2, P4) e quartzitos da Série de Candana (SN1, P1, P2, P3, P5). Os solos florestais apresentavam pH ácido (4,58-4,68), alta saturação de Al (75-90%) no complexo de troca de e baixa concentração de P disponível (4,78-11,96 mg kg-1); estes parâmetros melhoram em solos de pastagem, como resultado da calagem e fertilizantes aplicados, apresentando um pH entre 5,17 e 7,02; saturação por Al variando de 0,58 a 59,24% e P disponível entre 5,24 e 42,07 mg kg-1. Em relação aos metais pesados, a profundidade da amostra não afetou significativamente a sua concentração total, contrariamente ao que se verificou com o material parental, que apresentou as concentrações mais elevadas de Fe, As, Cu e Ni nos solos desenvolvidos a partir de ardósias possivelmente devido à presença de materiais piríticos. Na maioria dos casos, os metais pesados estudados apresentaram concentrações totais inferiores aos valores geralmente considerados como referência para solos desenvolvidos a partir dos respetivos materiais parentais, sendo sempre inferiores aos valores limite considerados fitotóxicos. Neste estudo, os solos naturais apresentaram valores de metais pesados semelhantes ou mesmo superiores aos dos solos fertilizados (exceto para o Zn na pastagem P4), o que indica que as doses aplicadas de fertilizantes não influenciaram de forma significativa os seus níveis de concentração.This work was funded by the Spanish Ministerio de Economía y Competitividad (Grant Reference: CGL2012-36805-C02-01)S

Enmienda de un suelo de mina con subproductos : efecto sobre la biomasa microbiana determinada mediante el uso de los ácidos grasos de los fosfolípidos

In the present work, the effect of two by-products (pine bark and crushed mussel shell) on microbial biomass and community structure was studied in a soil from a mine tailing located in a copper mine. In a laboratory experiment, different doses (0, 12, 24, 48, 96 and 192 Mg ha-1) of pine bark, crushed mussel shell or mixtures of both by-products were added to the soil. The amended soil samples were incubated for one year at 60% of water holding capacity, and then 33 phospholipid fatty acids (PLFAs) were extracted from these samples and quantified. The PLFAs concentrations were used for different microbial biomass estimations: total biomass, bacterial biomass, fungal biomass, gram-positive (G+) biomass and gram-negative (G-) biomass. The addition of crushed mussel had no significant effects on the total soil microbial biomass, either bacterial of fungal biomass. However, the addition of pine bark increased the total microbial biomass in the soil (up to 40%), mainly due to increases in the fungal biomass (it increased 1600%). No synergistic effects were observed when the soil was amended with both, pine bark and crushed mussel shell. The main community structure changes were due to the addition of pine bark to the soil, and were also due to modifications in fungal communities. Our results suggest that the microbial biomass was mainly limited in the mine soil by low organic matter concentrations, and therefore, practices increasing the amount of soil organic matter should be priorities for soil reclamation.En el presente trabajo se estudió el efecto de dos subproductos (corteza de pino y concha de mejillón triturada) sobre la biomasa y estructura microbiana de un suelo procedente de una escombrera localizada en una mina de cobre. En un experimento realizado en laboratorio fueron añadidas al suelo diferentes dosis (0, 12, 24, 48, 96 and 192 Mg ha-1) de corteza de pino, concha de mejillón triturada y mezclas de ambos subproductos. Las muestras de suelo enmendado fueron incubadas durante un año al 60% de la capacidad de campo, y posteriormente 33 ácidos grasos de los fosfolípidos (PLFAs) fueron extraídos de estas muestras y cuantificados. La concentración de PLFAs fue utilizada para realizar distintas estimaciones de la biomasa microbiana: biomasa total, biomasa bacteriana, biomasa fúngica, biomasa de bacterias gram + y biomasa de bacterias gram -. La adición de concha de mejillón triturada no tuvo efectos significativos sobre la biomasa total ni sobre la biomasa bacteriana o fúngica. Sin embargo, la adición de corteza de pino al suelo incrementó la biomasa total del suelo (hasta un 40%), debido mayormente al incremento de la biomasa fúngica (se incrementó un 1600%). Tampoco se observaron efectos sinérgicos cuando el suelo fue enmendado con una mezcla de corteza de pino y concha de mejillón triturada. Los mayores cambios en la estructura de las comunidades microbianas fueron debidos a la adición de corteza de pino al suelo, y fueron además debidas a cambios en las comunidades fúngicas. Nuestros resultados sugieren que la biomasa microbiana del suelo de mina está mayormente limitada por la concentración de materia orgánica y, por tanto, deben ser priorizadas prácticas de manejo que contribuyan a incrementarla para la rehabilitación de este tipo de suelos.Neste trabalho foi estudado o efeito de dois subprodutos (casca de pinheiro e concha de mexilhão triturada) na biomassa e estrutura microbiana de um solo procedente de uma escombreira localizada numa mina de cobre. Numa experiência de laboratório, doses diferentes (0, 12, 24, 48, 96 e 192 Mg ha-1) de casca de pinheiro, concha de mexilhão triturada e misturas de ambos os subprodutos foram adicionados ao solo. Amostras de solo corrigido com os resíduos foram incubadas durante um ano a 60% da sua capacidade de retenção de água, e subsequentemente, 33 ácidos gordos dos fosfolípidos (PLFAs) foram extraídos a partir destas amostras e quantificados. A concentração de PLFAs foi usada para estimar vários tipos de biomassa microbiana: biomassa total, biomassa bacteriana, biomassa fúngica, biomassa de bactérias gram positivas e biomassa de bactérias gram negativas. A adição de concha de mexilhão triturada não teve nenhum efeito significativo na biomassa total ou na biomassa bacteriana ou fúngica. Porém, a adição de casca de pinheiro aumentou a biomassa microbiana do solo (até 40%), principalmente devido ao aumento da biomassa fúngica (a qual aumentou de 1600%). Não foi observado nenhum efeito de sinergismo quando o solo foi corrigido com uma mistura de casca de pinheiro e concha de mexilhão triturada. As maiores alterações na estrutura das comunidades microbianas foram produzidas pela adição de casca de pinheiro ao solo, as quais resultaram em alterações nas comunidades fúngicas. Os resultados sugerem que a biomassa microbiana do solo de mina é, maioritariamente limitada pela concentração de matéria orgânica. Assim, práticas que contribuam para o seu aumento devem ser prioritárias para a reabilitação deste tipo de solos