Nuevas técnicas en descontaminación y recuperación de aguas residuales: los humedales como filtros verdes

Los humedales se pueden definir como cualquier anomalía hídrica positiva en el paisaje, de origen natural o artificial, que no es ni un río ni un lago, y que se caracteriza por presentar comunidades biológicas o usos característicos que la diferencian del entorno (González- Bernáldez, 1988). Estos ecosistemas son de gran interés para la preservación de la biodiversidad, por encontrarse en ellos el hábitat de especies animales y vegetales en peligro de extinción. Pero además, los humedales son sistemas idóneos para combatir la contaminación difusa originada, por ejemplo, por vertidos de aguas residuales, excedentes agrícolas o sedimentos y aguas con elevados contenidos en metales tóxicos. Por este motivo se les ha llamado filtros verdes

Variations in Plant Zonation and Cover as Indicators of long-term changes in soil conditions: a case study in a mediterranean coastal salt marsh

This study summarizes the changes (1991-2004) in plant distribution and cover in relation to soil factors in a salt marsh impacted by surplus of water from agricultural origin. An elevation of the groundwater level was observed, which led to a homogenization in the saline gradient. The changes were reflected in a shift in vegetation distribution which included the disappearance of most of the zonation observed in 1991

Spontaneous vegetation colonizing abandoned metal(loid) mine tailings consistently modulates climatic, chemical and biological soil conditions throughout seasons

This study aimed to evaluate whether the improvement in soil conditions induced by the vegetation spontaneously colonizing abandoned metal(loid) mine tailings from semiarid areas is consistent throughout seasons and to identify if the temporal variability of that conditions is of similar magnitude of that of the surrounding forests. Soil climatic (temperature and moisture), chemical (pH, electrical conductivity and water-soluble salts and metal(loid)s) and biological (water-soluble organic carbon and ammonium, microbial biomass carbon, dehydrogenase and β-glucosidase activity, organic matter decomposition and feeding activity of soil dwelling organisms) parameters were seasonally evaluated for one year in bare soils and different vegetated patches within metalliferous mine tailings and surrounding forests in southeast Spain. The results indicated that the improvement in soil conditions (as shown by softening of climatic conditions and lower scores for salinity and water-soluble metals and higher for biological parameters) induced by vegetation colonization was consistent throughout seasons. This amelioration was more evident in the more complex vegetation patches (trees with herbs and shrubs under the canopy), compared to bare soils and simpler soil-plant systems (only trees), and closer to forest soils outside the tailings. Bare soils and, to a lesser extent, vegetation patches solely composed by trees, showed stronger seasonal variability in temperature, moisture content, salinity, and water-soluble metals. In contrast, changes in biological and biological-related parameters were more pronounced in the more complex vegetation patches within mine tailings and surrounding forests due to its greater biological activity. In summary, the results demonstrated that vegetation patches formed by spontaneous colonization act as microsites that modulate seasonal variability in soil conditions and stimulate biological activity. This suggests that tailings vegetation patches might have higher resilience against climate change effects than bare soils. Therefore, they should be preserved as valuable spots in the phytomanagement of metal(loid)s mine tailings from semiarid areas.The present study was supported by the project RESCLICONT (CGL2016-80981-R) funded by MCIN/AEI/10.13039/501100011033/ and FEDER A way to make Europe. A. Peñalver-Alcalá was hired by the project RESCLICONT. M.N. González-Alcaraz holds a Ramón y Cajal research contract from the Spanish Ministry of Science and Innovation (RYC2020-029322-I). We much appreciate the help of M. Carmen Tercero, Héctor M. Conesa and Irene Sánchez during field and laboratory work. Francisco J. Jiménez-Cárceles, from Biocyma environmental consulting, helped us in vegetation field work. We thank to the technicians of the SAIT-UPCT for their laboratory and analytical assessments

Germination studies in Juncus acutus L. (Juncaceae), Schoenus nigricans L. (Cyperaceae) and Arthrocnemum macrostachyum (Moric.) Moris (Chenopodiaceae) for salt-marshes restorati

Since the 1970’s, salt marshes have been reduced in area by a great antropogenic pressure derived from agriculture, and more recently, from demand for tourist urban facilities. Therefore, restoration and preservation of plant communities in salt marshes are needed. Among the perennial species that appear typically in maritime sands, on the Mediterranean region and western Europe Juncus acutus L. (Juncaceae), Schoenus nigricans L. (Cyperaceae) and Arthrocnemum macrostachyum (Moric.) Moris (Chenopodiaceae) frequently occur (Álvarez-Rogel et al., 2000; Vicente et al., 2007). On other hand soil salinity has traditionally been considered one of the most important physical factors in plant zonation of salt marshes (Fig.1). Álvarez-Rogel et al. (2006) related the increase in soil salinity in summer to a higher content in Cl−, Na+, SO42−, Ca2+, Mg2+ and K+. However, the relative percentages of Ca2+ and K+ decreased when salinity rose, leading to an imbalance in favour of the most toxic cations, such as Na+ and Mg2+. The same authors showed that the highest correlation coefficients for ions were between Cl− and Na+ and between Cl− and Mg2+. The use of the above mentioned species in restoration programs require to know the germination responses to light and temperature and their salinity tolerance during germination

Long-term artificial seawater irrigation as a sustainable environmental management strategy for abandoned solar salt works: The case study of Agua Amarga salt marsh (SE Spain)

Groundwater abstraction is among the main anthropogenic causes of wetland desiccation worldwide, and corrective measures must be taken to avoid degradation of this valuable ecosystems. A case study is the Agua Amarga salt marsh (≈180 ha) (SE Spain). Agua Amarga includes a solar saltwork pond network in operation between 1925 and 1975, when it was abandoned, and the ponds were colonized by salt marsh vegetation. In 2008 two desalination plants were operating in the marsh vicinity, which were supplied with groundwater. To mitigate the possible negative impact on the salt marsh ecosystem due to groundwater drawdown, in 2009 a sea water irrigation program was implemented. This paper summarizes the results of a ten-year monitoring program (2010–2020) to evaluate the effects of the irrigation program on groundwater levels and quality, soil salinity and moisture, and vegetation cover. During this period, average groundwater level was 2.5 m below the surface and around 1 m deep near the irrigated ponds. Groundwater salinity was not affected outside the saltmarsh, but inside, where the saltworks caused values to rise above 300 mS/cm, it decreased more than 150 mS/cm in some 20 m deep piezometers. Between 2012 and 2020, vegetation cover increased between ≈10 and ≈25 %, with halophyte species such as Arthrocnemum macrostachyum and Sarcocornia fruticosa being the most favoured. In areas with prolonged flooding, Ruppia maritima, a plant species that lives submerged in saline water, was found. In the irrigated areas, soil electrical conductivity (1:5 soil:water extracts) decreased from ≈7-14 mS cm-1 to ≈2-6 mS cm-1. We present an example of sustainable actions in a coastal wetland, where the exploitation of water resources in semiarid areas is combined with promoting natural habitats.Financial support for this research was provided by Mancomunidad de los Canales del Taibilla (http://www.mct.es). M.N. González-Alcaraz holds a Ramón y Cajal research contract from the Spanish Ministry of Science and Innovation (RYC2020-029322-I). We much appreciate the help of M. Carmen Tercero, Héctor M. Conesa and B. Aránega, from Technical University of Cartagena, and Francisco J. Jiménez-Cárceles, from Biocyma environmental consulting, during field and laboratory work. We thank to the technicians of the SAIT-UPCT for their laboratory and analytical assessments. Finally, we want to give special recognition to Doctor Tomás Rodríguez Estrella for his contributions in the field of hydrogeology

Denitrification of saline agricultural effluents through woodchips bioreactors in SE Spain

[SPA] El grave problema existente en la zona Campo de Cartagena‐Mar Menor debido a la alta carga de nitratos de los efluentes de las desalobradoras y de las aguas de drenaje agrícola ha llevado a buscar soluciones fáciles de implantar que permitan la eliminación de nitratos con un coste reducido. En este trabajo se ha evaluado la viabilidad de utilizar biorreactores, consistentes en depósitos o zanjas rellenos de astillas de madera u otros materiales lignocelulósicos a través de los cuales se hace pasar el agua para que se produzca la desnitrificación. Se han ensayado cuatro tipos de sustratos: cáscara de almendra, troceado de algarroba, hueso de oliva y astillas de cítrico, y se ha determinado que las astillas de cítrico son el más adecuado ya que mostraron el mejor rendimiento en la eliminación de nitrato (76%) siendo, además, el sustrato más económico de los cuatro ensayados. [ENG] The serious problem existing in the Campo de Cartagena-Mar Menor area due to the high nitrate load of desalination and agricultural drainage effluents has led to the search for easy-to-implement solutions that allow removing nitrates at a reduced cost. Among the possible measures, we find the use of bioreactors which consist on lignocellulosic materials of low cost as carbon source so that microorganisms can complete the denitrification in a container, tank or ditch in which the stagnant water is kept for long enough or circulating slowly. Four types of carbon media have been tested: almond shell, chopped carob, olive bone and citrus woodchip, and it has been determined that citrus woodchips are the most suitable because show the best performance in removing nitrate (76%) being, in addition, the most economical carbon media of the four tested.Este proyecto está siendo financiado parcialmente por la Cátedra de Agricultura Sostenible para el Campo de Cartagena, y por la entidad de saneamiento y depuración de aguas residuales de la Región de Murcia (ESAMUR). Carolina Díaz García fue becaria de la Cátedra y actualmente está contratada a cargo de un proyecto Art. 83 suscrito entre la UPCT y ESAMUR

Functional and structural soil regeneration in abandoned mine tailings from semiarid Mediterranean areas: relationships with spontaneous plant colonization

[SPA] Los ecosistemas terrestres degradados por residuos mineros, cuyas características funcionales y estructurales están deterioradas, pueden presentar condiciones estresantes para los organismos vivos, además de suponer un riesgo de transferencia de compuestos potencialmente tóxicos al medio. El objetivo de este trabajo fue evaluar el desarrollo edáfico, estructural y funcional, del suelo asociado a distintas etapas de colonización vegetal espontánea, relacionados con la regeneración del ecosistema, en ambientes Mediterráneos afectados por residuos mineros. Se evaluaron diversos parámetros estructurales (estructura; pH; salinidad; carbono orgánico total; nitrógeno total; metales) y funcionales (carbono de la biomasa microbiana; la actividad β-glucosidasa; el estudio de grupos funcionales de microorganismos) del suelo de cinco ambientes degradados con diferente grado de colonización vegetal, además de en un bosque control sin contaminación. Se observó que existen diferencias estructurales y funcionales entre ambientes, con propiedades del suelo y respuestas funcionales de los ecosistemas más próximas a las del bosque control en los ambientes con mayor colonización vegetal. [ENG] Terrestrial ecosystems degraded by mine waste with functional and structural characteristics deteriorated, can present stressful conditions to organisms, also to mean a transfer risk of potentially toxic compounds to environment. The aim of this study was to assess the soil development, structural and functional, associated to different spontaneous plant colonization stages related with ecosystem regeneration, in Mediterranean environments affected by mine waste. Structural (structure; pH; salinity; total organic carbon; total nitrogen; metals) and functional (microbial biomass carbon; β-glucosidase activity; functional groups of microorganisms study) soil parameters were evaluated in five degraded environments with different plant colonization stage, as well as, a control forest without pollution. Structural and functional differences between environments were observed, with soil properties and functional response of ecosystems closer to control forest in the environments with higher plant colonization.Trabajo financiado por el Ministerio de Industria, Economía y Competitividad (CGL2016-80981-R) y por fondos FEDER y por Campus Mare Nostrum de Excelencia Internacional a través de su Ayuda para la realización de estancias externas de jóvenes investigadores asociados a redes y nodos CMN durante el curso académico 2018/2019

Effect and evolution of organic amendments application on the functionality of metallic mine tailings soils in environments under Mediterranean climate

[SPA] Los depósitos de minería metálica presentan condiciones desfavorables que dificultan la funcionalidad del suelo y la colonización vegetal. El objetivo de este trabajo fue evaluar si la adicción de enmiendas orgánicas (compost de residuos sólidos urbanos + biochar de restos de podas) mejora la funcionalidad de suelos desnudos de un depósito bajo clima Mediterráneo y si favorece la colonización espontánea de la vegetación. Se evaluaron diversos parámetros estacionalmente durante un año tras la adición de las enmiendas (p.e. pH; salinidad; carbono orgánico soluble; metales solubles; carbono de la biomasa microbiana y descomposición de la materia orgánica) La adición de enmiendas orgánicas mejoro las condiciones del suelo. Esto mejoró la funcionalidad microbiana del suelo, que persistió estacionalmente, y favoreció la colonización espontánea de la vegetación. [ENG] Metallic mine tailings present unfavorable soil conditions that hinder soil functionality and plant colonization. The aim of this study was to asses if the addition of organic amendments (compost of urban solid waste + biochar from pruning trees) improved the functionality of bare tailing soils under Mediterranean climate and favored spontaneous plant colonization. A series of soil parameters were seasonally evaluated after organic amendments addition during one year (e.g., pH, salinity, soluble organic carbon, soluble metals, carbon from microbial biomass and decomposition of organic matter). Organic amendments addition improved soil conditions. This enhanced soil microbial functionality, which persisted seasonally, and favored spontaneous plant colonization.Trabajo financiado por el Ministerio de Economía y Competitividad de España a través de fondos FEDER (Proyecto RESCLICONT- CGL2016-80981-R)

Functional regeneration of soils affected by mine wastes in Mediterranean environments and their resilience against climate change scenarios

[SPA] Los suelos afectados por residuos mineros pueden presentar condiciones estresantes para los organismos vivos, además de suponer un riesgo de transferencia de compuestos potencialmente tóxicos al medio. Esto podría verse agravado en un futuro, ya que tales suelos, cuyas características funcionales y estructurales están deterioradas, tendrán menor capacidad de adaptación (resiliencia) frente al cambio climático. El objetivo de la tesis doctoral es conocer aspectos funcionales y estructurales del suelo relacionados con la regeneración del ecosistema, en ambientes Mediterráneos afectados por residuos mineros, y valorar su resiliencia frente a escenarios de cambio climático. Para ello se estudiarán ambientes con distinto grado de colonización vegetal. Además, se pretende evaluar si la adición de enmiendas orgánicas puede contribuir a mejorar la funcionalidad de los suelos y su respuesta frente a dichos escenarios. Los resultados iniciales indican que pueden existir diferencias funcionales y estructurales entre los distintos ambientes seleccionados, relacionadas con diferentes etapas de colonización vegetal. La adición de enmiendas orgánicas a estos suelos puede ser una práctica de manejo adecuada para mejorar sus propiedades. [ENG] Soils affected by mine wastes might show stressful conditions for biota, as well as to pose a risk of transfer of potentially toxic compounds to the environment. This may worsen in the upcoming decades since these soils, whose functional and structural characteristics are deteriorated, will have less adaptation capability (resilience) to climate change. The objective of the thesis is to know functional and structural aspects of the soil related to ecosystem regeneration, in Mediterranean environments affected by mine wastes, and to evaluate its resilience against climate change scenarios. Moreover, the aim is also to evaluate if organic amendments addition might improve soil functionality and its response to changing climate conditions. To achieve this, environments with different degree of vegetal colonization will be studied. The initial results show that functional and structural differences might exist among the different environments selected, in relation with the distinct stage of vegetal colonization. The addition of organic amendments to these soils could be an adequate management practice to improve their properties.Proyecto financiado por el Ministerio de Industria, Economía y Competitividad (CGL2016-80981-R) y por fondos FEDER

The relationships between functional and physicochemical soil parameters in metal(loid) mine tailings from Mediterranean semiarid areas support the value of spontaneous vegetation colonization for phytomanagement

Spontaneous growth of native vegetation in abandoned metal(loid) mine tailings can be valuable for phytomanagement restoration projects. This study aimed to assess the degree to which spontaneous plant colonization of abandoned metal(loid) mine tailings from Mediterranean semiarid areas led to functional soil improvement, and to identify, if possible, a critical level indicating that this functionality was moving towards that of the vegetated soils from the surroundings. Vegetation ecological indexes, plant life forms and species functional roles, together with physicochemical and functional soils parameters, were studied in metal(loid) mine tailings abandoned ~40 years ago and surrounding forests in SE Spain. Vegetation patches showed only small differences in physicochemical parameters related to soil abiotic stress conditions (pH, salinity and metals), regardless of the vegetation. However, vegetation patches with greater species diversity and richness and presence of plants with contrasted life forms and functional traits that facilitate the growth of less stress-tolerant species showed an increase of the soil microbial functionality (higher microbial biomass C, β-glucosidase activity, bacterial metabolic activity and functional diversity). Moreover, these vegetation patches showed a functional soil status comparable to that of the forests outside the mine tailings. In this sense, the present study showed the value of preserving these vegetation patches since they may act as nucleation spots favoring positive plant-soil feedbacks that may help to accelerate the functional recovery of these degraded areas. Furthermore, strategies to promote the creation of new vegetation patches including a variety of species with contrasted life forms and functional traits should be considered in phytomanagement restoration projects for abandoned metal(loid) mine tailings.The present study was supported by the project RESCLICONT (CGL2016-80981-R), funded by the Ministry of Science, Innovation and Universities of Spain through FEDER funds; by the project METOXCLIM (PTDC/CTA-AMB/29557/2017), funded by FEDER, through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI), and by national funds (OE), through FCT/MCTES. Thanks are due to FCT/MCTES for the financial support to CESAM (UIDP/50017/2020+UIDB/50017/2020), through national funds. A. Peñalver-Alcalá was hired by the project RESCLICONT and received a grant from the Technical University of Cartagena for a short stay at the University of Aveiro. S. Peixoto holds a PhD grant (SFRH/BD/117738/2016) from FCT. I. Silva received a research fellowship from the METOXCLIM project (BI/CESAM/0063/METOXCLIM/2018). A.R.R. Silva received a research fellowship from the METOXCLIM project (BI/CESAM/00060/METOXCLIM/2018). M.N. González-Alcaraz holds a Saavedra Fajardo research contract from the Séneca Foundation of the Murcia Region. The authors thank F.J. Jiménez-Cárceles from Biocyma S.L. for his valuable help with vegetation fieldwork