Mycoremediation with Agaricus bisporus and Pleurotus ostreatus growth substrates versus phytoremediation with Festuca rubra and Brassica sp. for the recovery of a Pb and γ-HCH contaminated soil.

Mycoremediation with mushroom growth substrates can be used for the recovery of mixed contaminated soils due to the benefits derived from the physicochemical characteristics of the substrates, the activity of extracellular enzymes secreted by the fungi, and the presence of the fungal mycelia. The objective of this work was to assess the potential of Agaricus bisporus and Pleurotus ostreatus growth substrates (inoculated mushroom substrates vs. spent mushroom substrates) for the mycoremediation of soils co-contaminated with lead and lindane (γ-HCH). We compared the efficiency of these mycoremediation strategies with the phytoremediation with Brassica spp. Or Festuca rubra plants, in terms of both reduction in contaminant levels and enhancement of soil health. An enhanced soil health was achieved as a result of the application of mycoremediation treatments, compared to phytoremediation and control (untreated) treatments. The application of P. ostreatus inoculated substrate led to the most significant reduction in γ-HCH concentration (up to 88.9% compared to corresponding controls). In the presence of inoculated mushroom substrate, P. ostreatus fruiting bodies extracted more Pb than Brassica spp. Or F. rubra plants. Mycoremediation with P. ostreatus growth substrates appears a promising strategy for the recovery of the health of soils co-contaminated with Pb and γ-HCH.

Application of in situ bioremediation strategies in soils amended with sewage sludges.

Increasing soil loss and the scarcity of useful land requires new reusing strategies. Thus, recovery of polluted soils recovery offers a chance for economic and social regeneration. With this objective, different soil cleaning technologies have been developed during the last few decades. On one hand, classical physical and/or chemical technologies can be found which are efficient, but have high costs and impacts upon ecosystems. On the other hand, biological methods (such as phytoremediation, bioremediation and vermiremediation) are relatively cost effective and eco-friendly, but also more time-consuming. These biological methods and their yields have been widely studied but little is known about the interaction between different soil cleaning methods. The combination of different biological strategies could lead to an improvement in remediation performance. Hence, in the present work, different micro-, vermi- and phyto-remediation combinations are applied in a sewage sludge polluted landfill in Gernika-Lumo (Basque Country) which was used as a disposal point for decades, in search of the treatment (single) or combination (dual or triple) of treatments with best remediation yields. Eight experimental groups were applied (n=3) placing earthworms (E), bacteria (B), plants (P), bacteria+earthworms (B+E), bacteria+plants (B+P), plants+earthworms (P+E) plants+bacteria+earthworms (P+B+E) and a non-treated (N.T.) group in the experimental plot (Landfill 17), for 12 months. In order to assess the efficiency of each treatment, a complete characterization (chemical and ecotoxicological) was carried out before and after remediation. Results showed high removal rates for dieldrin (between 50% and 78%) in all the experimental groups. In contrast, removal rates around 20-25% were achieved for heavy metals (Cd 15%-35%; Ni 24%-37%; Pb 15%-33%; Cr 7%-39%) and benzo(a)pyrene (19.5%-28%). The highest reductions were observed in dual (P+E, B+E) and triple (P+B+E) treatments. The best elimination yields were obtained after P+B+E treatment, as highlighted by the battery of ecotoxicological tests and bioassays performed with earthworms, plants and bacteria.

The impact of nanoscale zero-valent iron particles on soil microbial communities is soil dependent.

The application of nanoscale zero-valent iron particles (nZVI) for the remediation of contaminated sites is very promising. However, information concerning the ecotoxicity of nZVI on soil microbial communities and, hence, soil quality, is still scarce. We carried out a three-month experiment to evaluate the impact of the application of different concentrations of nZVI (from 1 to 20 mg g DW soil-1) on soil microbial properties in a clay-loam versus a sandy-loam soil. Data on microbial biomass (total bacteria and fungi by qPCR, microbial biomass carbon), activity (ß-glucosidase, arylsulphatase and urease activities), and functional (Biolog Ecoplates™) and structural (ARISA, 16S rRNA amplicon sequencing) diversity evidenced that the sandy-loam soil was more vulnerable to the presence of nZVI than the clay-loam soil. In the sandy-loam soil, arylsulphatase activity and bacterial abundance, richness and diversity were susceptible to the presence of nZVI. The high content of clay and organic matter present in the clay-loam soil may explain the observed negligible effects of nZVI on soil microbial properties. It was concluded that the impact of nZVI on soil microbial communities and, hence, soil quality, is soil dependent.

Data on the selection of biostimulating agents for the bioremediation of soil simultaneously contaminated with lindane and zinc.

The bioremediation of contaminated soil often involves the addition of organic/inorganic amendments and mobilizing agents (e.g. surfactants, detergents), in order to stimulate the growth and degrading activity of soil microbial populations and increase contaminant bioavailability. For this data article we carried out an experiment to select biostimulating agents for the bioremediation of soil simultaneously contaminated with lindane (HCH, 10 mg kg-1 DW soil) and Zinc (Zn, 1500 mg kg-1 DW soil). To this purpose, a factorial design was used to test the effect of three organic amendments (i.e. hen manure, composted horse manure, cow slurry) and three mobilizing agents (i.e. sodium dodecylbenzenesulfonate (SDS), rhamnolipids and Tween-80) on the reduction of total HCH and bioavailable Zn concentration in soil. Similarly, the effect of the addition of cyclohexane, as chemical inducer of HCH degradation, was also studied. The addition of SDS, rhamnolipids and Tween-80 significantly reduced HCH concentration in soil, regardless of the presence of other biostimulating agents. When added individually, the three organic amendments (hen manure, composted horse manure, cow slurry) significantly reduced bioavailable Zn concentration in soil. These data provide useful information for the bioremediation, through biostimulation, of soils simultaneously contaminated with HCH and Zn.

Short-term effects of non-grazing on plants, soil biota and aboveground-belowground links in Atlantic mountain grasslands.

Mountain grasslands in the Iberian Peninsula are the result of extensive grazing. However, a progressive abandonment of grazing activity is currently observed in the study region. The objective of this work was to evaluate the short-term (2 years) effects of non-grazing on the diversity and composition of plants, soil microorganisms (prokaryotes, fungi, arbuscular mycorrhiza), mesofauna, macrofauna and aboveground-belowground links, through the study of 16 grazed vs. non-grazed areas in Atlantic grasslands located in the Basque Country (Spain). Sites were divided between 4 habitat types with different elevation, pasture productivity, vegetation type and parent material. Herbivores appeared to influence plant community composition, contributing to increase aboveground diversity, while having unequal effects on belowground communities depending on the organisms analysed. This may be explained by the different habitat and trophic level of each soil organism, which may be more or less affected by the predominating negative effects of grazing, such as soil compaction, and only partially compensated by other positive effects. Finally, habitat type appeared to be the strongest influence on both above- and belowground communities, also influencing the effect of the absence of grazing.

The Community Structures of Prokaryotes and Fungi in Mountain Pasture Soils are Highly Correlated and Primarily Influenced by pH.

Traditionally, conservation and management of mountain pastures has been managed solely on the basis of visible biota. However, microorganisms play a vital role for the functioning of the soil ecosystem and, hence, pasture sustainability. Here, we studied the links between soil microbial (belowground) community structure (using amplicon sequencing of prokaryotes and fungi), other soil physicochemical and biological properties and, finally, a variety of pasture management practices. To this aim, during two consecutive years, we studied 104 environmental sites characterized by contrasting elevation, habitats, bedrock, and pasture management; located in or near Gorbeia Natural Park (Basque Country/Spain). Soil pH was found to be one of the most important factors in structuring soil microbial diversity. Interestingly, we observed a striking correlation between prokaryotic, fungal and macrofauna diversity, likely caused by interactions between these life forms. Further studies are needed to better understand such interactions and target the influence of different management practices on the soil microbial community, in face of the significant heterogeneity present. However, clearing of bushes altered microbial community structure, and in sites with calcareous bedrock also the use of herbicide vs. mechanical clearing of ferns.

Impact of sources of environmental degradation on microbial community dynamics in non-polluted and metal-polluted soils.

Soils are currently being degraded at an alarming rate due to increasing pressure from different sources of environmental degradation. Consequently, we carried out a 4-month microcosm experiment to measure the impact of different sources of environmental degradation (biodiversity loss, nitrogen deposition and climate change) on soil health in a non-polluted (non-degraded) and a heavily metal-polluted (degraded) soil, and to compare their responses. To this aim, we determined a variety of soil microbial properties with potential as bioindicators of soil health: basal respiration; ß-glucosaminidase and protease activities; abundance (Q-PCR) of bacterial, fungal and chitinase genes; richness (PCR-DGGE) of fungal and chitinase genes. Non-polluted and metal-polluted soils showed different response microbial dynamics when subjected to sources of environmental degradation. The non-polluted soil appeared resilient to "biodiversity loss" and "climate change" treatments. The metal-polluted soil was probably already too severely affected by the presence of high levels of toxic metals to respond to other sources of stress. Our data together suggests that soil microbial activity and biomass parameters are more sensitive to the applied sources of environmental degradation, showing immediate responses of greater magnitude, while soil microbial diversity parameters do not show such variations.