Antibiotic resistance is a growing global problem, with agricultural practices and climate change as substantial contributors to the spread of antibiotic resistance genes (ARGs) in the environment. We investigated the effect of drought and fertilization type (organic vs. mineral) on radish crop growth and soil prokaryotic communities, with special emphasis on the radish and soil resistomes, as measured by the relative abundance of ARGs and mobile genetic element (MGE)-linked genes. Manure fertilization significantly increased ARG relative abundances in soil, compared to mineral fertilization. Drought and the presence of radish plants emerged as key variables regulating the association between ARGs and MGE-linked genes. Nonetheless, despite radish being a belowground crop, no direct connection was observed between the soil and crop resistomes. These results suggest that soil moisture and fertilization strategies do not necessarily increase the risk of ARG transfer to human pathogens through crop consumption. Consequently, a robust risk assessment of the environmental resistome must account for all compartments within the transmission chain. Together, our findings highlight the complex interplay between agricultural practices and climatic factors in shaping the soil and crop resistome.

Antibiotic resistance is a growing global problem, with agricultural practices and climate change as substantial contributors to the spread of antibiotic resistance genes (ARGs) in the environment. We investigated the effect of drought and fertilization type (organic vs. mineral) on radish crop growth and soil prokaryotic communities, with special emphasis on the radish and soil resistomes, as measured by the relative abundance of ARGs and mobile genetic element (MGE)-linked genes. Manure fertilization significantly increased ARG relative abundances in soil, compared to mineral fertilization. Drought and the presence of radish plants emerged as key variables regulating the association between ARGs and MGE-linked genes. Nonetheless, no connection was observed between the soil and crop resistome, despite radish being a belowground product, suggesting that, under our experimental conditions, the consumption of a belowground crop product does not pose a potential risk of transmission of ARGs from agroecosystems to human bacterial pathogens. Our findings highlight the complex interplay between agricultural practices and climatic factors in shaping the soil and crop resistome.

The remediation of mixed contaminated soil is challenging as it often requires actions to minimize metal-induced risks while degrading organic contaminants. Here, the effectiveness of different bioremediation strategies, namely, rhizoremediation with native plant species, mycoremediation with Pleurotus ostreatus spent mushroom substrate, and biostimulation with organic by-products (i.e., composted sewage sludge and spent mushroom substrate), for the recovery of a mixed contaminated soil from an abandoned gravel pit was studied. The combination of biostimulation and rhizoremediation led to the most significant increase in soil health, according to microbial indicator values. The application of composted sewage sludge led to the highest reduction in anthracene and polychlorinated biphenyls concentrations. None of the strategies managed to decrease contamination levels below regulatory limits, but they did enhance soil health. It was concluded that the biological remediation treatments improved soil functioning in a short time, before the concentration of soil contaminants was significantly reduced.

Landfills and waste disposal sites in the Basque Country are summarized in the inventory of soils that either currently support or have supported potentially polluting activities or facilities (Law 4/2015). Notably, “Landfill 17,” located in Gernika-Lumo, has been receiving, for decades, sewage sludges from the local wastewater treatment plant (WWTP) as agricultural amendment. In order to decontaminate and recover soil functionality, a combination of bioremediation (which involved bioagumentation and phyto- and vermitechnologies) and complementary bioremediation strategy (i.e., promotion and maintenance of the native vegetation) was implemented in situ. Physicochemical and ecotoxicological characterization were achieved. Furthermore, an ecotoxicological assessment of the soils upon flora and fauna was carried out through the application of different bioassays and biomarkers. Additionally, an integrative biomarker response (IBR/n) index was calculated to provide a holistic view of the soil general status. Critical pollutants [Cd, Cr, Ni, Pb, benzo(a)pyrene, and dieldrin] were observed in most of the treated sites. Microbial parameters did not present remarkable differences among sites. However, plant indicators pointed the non-treated site (MN8) as the unhealthiest. This was also observed in earthworms’ immune system, where cytotoxicity appears when exposed to non-treated soils. In conclusion, this field study showed that the combination of bioaugmentation, phytoremediation with native species, and vermiremediation is highly useful in eliminating mixed contamination, improving soil health, and ultimately restoring ecosystem functionality and biodiversity.

Anthropogenic activities have resulted in the buildup of contaminants in the soil, posing risks to ecosystems and human health. The revitalization of contaminated sites from former industrial activities is a matter of much interest and concern since they are usually located in urban or peri-urban areas. The transformation of brownfields into greenfields normally requires remediation interventions that address soil contamination. Traditional physicochemical techniques of soil remediation often involve a high economic cost and environmental disturbance. Operational costs and more stringent environmental regulations at disposal sites are making on-site and, above all, in-situ biological remediation technologies more attractive. The aim of biological remediation techniques is not only to decrease the concentration of soil contaminants, but also to recover soil health and the provision of ecosystem services. The selection of the most suitable biological remediation strategies depends on a variety of factors, such as the nature of the contaminants, their concentration and bioavailability, the depth of contamination, soil properties and edaphoclimatic conditions, economic cost, environmental policies, and so on. Among the different biological remediation strategies, this chapter provides a review of plant-based remediation strategies (phytoremediation, phytomanagement) for the remediation of contaminated soils, including microbial-assisted phytoremediation. In addition, we present a case study on the application of compost-assisted phytoremediation, using intercropping with poplar trees and alfalfa, for the recovery of an industrial contaminated soil.

The quantification of phytochemicals with nutritional benefits relies on accuracy yet time-consuming, expensive and destructive methodologies. In contrast, optical indices widely employed in disciplines such as ecology can serve as fast, low-cost, and non-destructive tools for tracking pigment changes. However, their potential application in postharvest phases and commercialization (i.e., supermarkets) remains underexplored. In this context, this work aimed to investigate the feasibility of using the normalized difference vegetation index (NDVI), the chlorophyll content index (CCI) and the photochemical reflectance index (PRI) to estimate phytochemicals of nutraceutical interest (chlorophylls, carotenoids and tocopherols). A fully factorial and randomized experimental design (combining different illumination, packaging, and collecting time) was conducted in two green leafy packaged vegetables (rocket and spinach). With this design that induced differences in physiological parameters a database with variable content of isoprenoids (carotenoids, chlorophylls, and tocopherols) based on treatments was created. By establishing correlations and models between isoprenoids and optical indices, the NDVI was revealed as a valuable tool to estimate chlorophyll content in both species, while the PRI tracked both tocopherol and carotenoid (except for β-carotene) content. Taking this approach, estimation of the sum of total carotenoids and tocopherols was achieved using the PRI. This study confirms the possibility of extending the use of the NDVI and PRI to real-time nutritional monitoring in different stages of production and commercialization. A future application envisions integrating this technology into refrigerators for enhanced consumer access to nutritional information.

Abstract The biological remediation of mixed contaminated soils is exceedingly challenging as it often requires actions to minimize metal-induced risks while degrading organic contaminants. In this study, we assessed the effectiveness of three biological remediation options (rhizoremediation, biostimulation, mycoremediation), applied together or separately, for the recovery of a mixed contaminated soil from a gravel pit. We evaluated the effectiveness of these remediation strategies in terms of both reduction in soil contamination levels and recovery of soil health. The combination of biostimulation (by the application of composted sewage sludge) and rhizoremediation with Medicago sativa plants resulted in the highest recovery of soil health. The application of the composted sewage sludge led to the highest reduction in anthracene and polychlorinated biphenyls concentrations. Still, the studied biological remediation options did not manage to decrease soil contamination levels below some of the limits set by the regional legislation. By contrasts, they enhanced soil health, as reflected by the values of soil microbial indicators, pointing out to the fact that they can stimulate soil functioning in a relatively short period of time, long before the concentration of soil contaminants is significantly reduced.

Many species of Alternaria are important pathogens that cause plant diseases and postharvest rots. They lead to significant economic losses in agriculture and affect human and animal health due to their capacity to produce mycotoxins. Therefore, it is necessary to study the factors that can result in an increase in A. alternata. In this study, we discuss the mechanism by which phenol content protects from A. alternata, since the red oak leaf cultivar (containing higher phenols) showed lower invasion than the green one, Batavia, and no mycotoxin production. A climate change scenario enhanced fungal growth in the most susceptible cultivar, green lettuce, likely because elevated temperature and CO2 levels decrease plant N content, modifying the C/N ratio. Finally, while the abundance of the fungi was maintained at similar levels after keeping the lettuces for four days at 4 °C, this postharvest handling triggered TeA and TEN mycotoxin synthesis, but only in the green cultivar. Therefore, the results demonstrated that invasion and mycotoxin production are cultivar- and temperature-dependent. Further research should be directed to search for resistant cultivars and effective postharvest strategies to reduce the toxicological risk and economic losses related to this fungus, which are expected to increase in a climate change scenario.

Plants have to cope with different biotic and abiotic stresses, such as the attacks of pathogens and herbivores, high irradiance, droughts, salt stress or nutrient deficiencies throughout their lifetime. These environmental perturbations lead to the regulation of the “primary” and “secondary” carotenoid network. The formers are produced and stored in plastids and they are necessary for photosynthesis and related functions. Otherwise, secondary carotenoids are derivatives of primary carotenoids. They perform other important functions not related to the photosynthetic process but essential for plant survival as regulators of growth and development or as signal molecules at all levels of plant organization. This review provides a complete revision of the status of all these carotenoids, highlighting their newly discovered functions involved in plant-environment interaction. Concurrently, this review covers recent information on how carotenoids perform critical functions for the survival of animals (including humans) and the way they are suitable diagnostic tools for assessing the functioning of terrestrial ecosystems.

Abstract The biological remediation of mixed contaminated soils is exceedingly challenging as it often requires actions to minimize metal-induced risks while degrading organic contaminants. In this study, we assessed the effectiveness of three biological remediation options (rhizoremediation, biostimulation, mycoremediation), applied together or separately, for the recovery of a mixed contaminated soil from a gravel pit. We evaluated the effectiveness of these remediation strategies in terms of both reduction in soil contamination levels and recovery of soil health. The combination of biostimulation (by the application of composted sewage sludge) and rhizoremediation with Medicago sativa plants resulted in the highest recovery of soil health. The application of the composted sewage sludge led to the highest reduction in anthracene and polychlorinated biphenyls concentrations. Still, the studied biological remediation options did not manage to decrease soil contamination levels below some of the limits set by the regional legislation. By contrasts, they enhanced soil health, as reflected by the values of soil microbial indicators, pointing out to the fact that they can stimulate soil functioning in a relatively short period of time, long before the concentration of soil contaminants is significantly reduced.

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.

Soil is one of our most important natural resources. Regrettably, the expansion of human activities has resulted in the degradation of the soil resource due to contamination with a myriad of organic and inorganic compounds. The remediation of mixed contaminated soils, i.e. soils contaminated with both organic compounds and metals, is challenging as it requires actions to simultaneously decrease metal-induced risks and organic contaminant concentrations. Here, we evaluated the effect of the addition of zero-valent iron nanoparticles (nanoremediation) and organic amendments (biostimulation) on the rhizoremediation, using Brassica napus plants, of soil simultaneously contaminated with zinc (2500 mg kg −1) and lindane (100 mg kg−1). We used a factorial design with three factors (amendment, nZVI, plant) to evaluate the impact of the applied remediation actions on lindane and extractable Zn concentrations, as well as on soil health recovery as manifested by the values of different soil microbial indicators. The studied microbial indicators were not negatively affected by nZVI application. The application of nZVI was the most effective factor regarding the targeted reduction in lindane concentration (51% average reduction in nZVI treated soils). The highest reduction in extractable Zn was achieved in the presence of B. napus, nZVI and organic amendments (99 and 95% reduction in horse manure-amended and sewage sludge-amended soils, respectively). The combination of the three factors led to the highest values of soil microbial indicators (although a significant triple interaction was not observed for all parameters), especially when combined with horse manure amendment: in this case, prokaryotic richness increased by 64%, respiration by 376%, eukaryotic abundance by 333%, and prokaryotic abundance by 437%, compared to untreated soils. The combination of remediation approaches (rhizoremediation with B. napus, nanoremediation with nZVI, biostimulation with organic amendments) can help overcome the limitations of each individual strategy.

The coronavirus disease (COVID-19) has had a great global impact on human health, the life of people, and economies all over the world. However, in general, COVID-19 ' s effect on air quality has been positive due to the restrictions on social and economic activity. This study aimed to assess the impact on air quality and metal deposition of actions taken to reduce mobility in 2020 in two different urban locations. For this purpose, we analysed air pollution (NO2, NO, NOx, SO2, CO, PM10, O-3) and metal accumulation in leaves of Tilia cordata collected from April to September 2020 in two cities in northern Spain (Pamplona-PA and San Sebasti ' an-SS). We compared their values with data from the previous year (2019) (in which there were no mobility restrictions) obtained under an identical experimental design. We found that metal accumulation was mostly lower during 2020 (compared with 2019), and lockdown caused significant reductions in urban air pollution. Nitrogen oxides decreased by 33% 44%, CO by 24% 38%, and PM10 by 16% 24%. The contents of traffic-related metals were significantly reduced in both studied cities. More specifically, significant decreases in metals related to tyre and brake wear (Zn, Fe, and Cu) and road dust resuspension (Al, Ti, Fe, Mn, and Ca) were observed. With these results, we conclude that the main reason for the improvement in urban air pollutants and metals was the reduction in the use of cars due to COVID-19 lockdown. In addition, we offer some evidence indicating the suitability of T. cordata leaves as a tool for biomonitoring metal accumulation. This information is relevant for future use by the scientific community and policy makers to implement measures to reduce traffic air pollution in urban areas and to improve environmental and human health.

As bryophytes present the capacity to colonize a wide range of habitats, including extreme environments (e.g., mine areas), we first checked the global response of bryophytes to heavy metals (HM) by a systematic review. This analysis found i) the lack of studies in a polluted environment and ii) resulted in a global trend of photochemical efficiency decrease when bryophytes faced heavy metals. Secondly, we characterized the photoprotective responses of four metallicolous populations of mosses (Lewinskya rupestris, Polytrichum commune, Ptychostomum compactum and Rhynchostegium confertum) naturally growing in an abandoned mine area by an experimental field approach. As a result, we found markedly species-specific tolerance patterns: i) less tolerant species, presenting high pollutants content accompanied by marked dissipative and antioxidative strategies. This strategy was depicted by the species R. confertum that result to be a good sentinel species due to the high pollutant content and high physiological sensitivity.; ii) intermediate tolerant species presenting a medium content of pollutants and less marked photoprotective mechanisms, and iii) most tolerant species minimizing pollutants content and consequently presenting no changes in their physiological performance. This evidence support that species' bryological attributes have a key role in determining species' tolerance towards environmental heavy metals, and should be taken into consideration in future studies. The findings of this study also pointed out that the higher levels of gamma + beta-tocopherol in metallicolous populations could play a regulatory role in metal stress tolerance in mosses and it could be a suitable functional responsive trait for environmental response prediction to heavy metals in polluted environments.

Dehesas, human-shaped savannah-like ecosystems, where the overstorey is mainly dominated by the evergreen holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.), are classified as a global conservation priority. Despite being Q. ilex a species adapted to the harsh Mediterranean environmental conditions, recent decades have witnessed worrisome trends of climate-change-induced holm oak mortality. Holm oak decline is evidenced by tree vigour loss, gradual defoliation and ultimately, death. However, before losing leaves, trees undergo leaf-level physiological adjustments in response to stress that may represent a promising field to develop biochemical early markers of holm oak decline. This study explored holm oak photoprotective responses (pigments, tocopherols and photosynthetic performance) in 144 mature holm oak trees with different health statuses (i.e., crown defoliation percentages) from healthy to first-stage declining individuals. Our results indicate differential photochemical performance and photoprotective compounds concentration depending on the trees' health status. Declining trees showed higher energy dissipation yield, lower photochemical efficiency and enhanced photoprotective compounds. In the case of total violaxanthin cycle pigments (VAZ) and tocopherols, shifts in leaf contents were significant at very early stages of crown defoliation, even before visual symptoms of decline were evident, supporting the value of these biochemical compounds as early stress markers. Linear mixed-effects models results showed an acute response, both in the photosynthesis performance index and in the concentration of foliar tocopherols, during the onset of tree decline, whereas VAZ showed a more gradual response along the defoliation gradient of the crown. These results collectively demonstrate that once a certain threshold of leaf physiological damage is surpassed, that leaf cannot counteract oxidative stress and progressive loss of leaves occurs. Therefore, the use of both photosynthesis performance indexes and the leaf tocopherols concentration as early diagnostic tools might predict declining trends, facilitating the implementation of preventive measures to counteract crown defoliation.

Fuels from renewable biological resources are currently being used as an alternative or complement to petroleum-derived fossil fuels. The objective of this work was to investigate the degradation dynamics of commercially-available biodiesel blends (containing 1, 5 or 16% biodiesel, i.e. B1, B5 and B16) in soil simultaneously polluted with metals and biodiesel blends. To this purpose, soil was artificially polluted with 6,000 mg biodiesel blend per kg DW soil (B1, B5 or B16) and a mixture of metals: 1,500 mg Zn kg(- 1) DW soil + 500 mg Cu kg(-1) DW soil + 50 mg Cd kg(-1) DW soil. Artificially-polluted soils were then arranged in a phytotron under controlled conditions and monitored for 30 days. The bioremediation capacity of a bio-stabilized municipal solid waste, as organic amendment for biostimulation purposes, was evaluated. Soil health was monitored by measuring soil microbial indicators (biomass, activity and diversity parameters) and performing phytotoxicity bioassays with Cucumis sativus. The degradation of the fatty acid methyl esters (FAME) present in biodiesel was higher than that of the corresponding alkane homologues from diesel. The addition of the bio-stabilized municipal solid waste increased FAME degradation and microbial activity, and alleviated phytotoxicity. Cucumis sativus was more sensitive to pollution-induced effects than soil microbial communities. Our data showed that, after 30 days, organically-amended soils polluted with B16 experienced the greatest improvement in soil health (in the presence of the abovementioned metal mixture). It was concluded that biodiesel-containing fuel might cause a lower impact on soil health than diesel of fossil origin.

Soils contaminated by organic and inorganic pollutants like Cr(VI) and lindane, is currently a main environmental challenge. Biological strategies, such as biostimulation, bioaugmentation, phytoremediation and vermiremediation, and nanoremediation with nanoscale zero-valent iron (nZVI) are promising approaches for polluted soil health recovery. The combination of different remediation strategies might be key to address this problem. For this reason, a greenhouse experiment was performed using soil without or with an organic amendment. Both soils were contaminated with lindane (15 mg kg(-1)) and Cr(VI) (100 or 300 mg kg(-1)). After one month of aging, the following treatments were applied: (i) combination of bioaugmentation (actinobacteria), phytoremediation (Brassica napus), and vermiremediation (Eisenia fetida), or (ii) nanoremediation with nZVI, or (iii) combination of biological treatments and nanoremediation. After 60 days, the wellness of plants and earthworms was assessed, also, soil health was evaluated through physico-chemical parameters and biological indicators. Cr(VI) was more toxic and decreased soil health, however, it was reduced to Cr(III) by the amendment and nZVI and, to a lesser extent, by the biological treatment. Lindane was more effectively degraded through bioremediation. In non-polluted soils, nZVI had strong deleterious effects on soil biota when combined with the organic matter, but this effect was reverted in soils with a high concentration of Cr(VI). Therefore, under our experimental conditions bioremediation might be the best for soils with a moderate concentration of Cr(VI) and organic matter. The application of nZVI in soils with a high content of organic matter should be avoided except for soils with very high concentrations of Cr(VI). According to our study, among the treatments tested, the combination of an organic amendment, biological treatment, and nZVI was shown to be the strategy of choice in soils with high concentrations of Cr(VI) and lindane, while for moderate levels of chromium, the organic amendment plus biological treatment is the most profitable treatment.

Brownfield surface is expanding in Europe, but as often abandoned or underused, these areas become refuge for microbial, faunal and floral biodiversity. However, brownfield sites are generally contaminated, likely posing severe environmental risks. At a former wood preservation site contaminated with Cu, we evaluated the efficiency of compost and dolomitic limestone incorporation into the soil, followed by revegetation with Cu-tolerant grassy species, as a phytomanagement option to increase vegetation cover and plant diversity while reducing pollutant linkages. 7 years of phytomanagement enhanced natural revegetation through the improvement of soil physicochemical properties, particularly with compost-based amendments. The compost incorporation increased soil Cu solubility; however, no increment in Cu availability and a reduction in Cu-induced phytotoxicity were observed with the compost. The improved soil nutrient availability and the soil phytotoxicity mitigation in compost-amended soils facilitated over the 7 years the growth of beneficial plant colonists, including leguminous species, which can potentially promote essential soil functions. Soil treatments did not affect Cu uptake and translocation by plants and shoot Cu levels indicated no risk for the food chain. Overall, a long-term phytomanagement combining an initial amendment of compost and dolomitic limestone with the cultivation of Cu-tolerant grassy populations can ameliorate such Cu-contaminated soils, by mitigating risks induced by Cu excess, ultimately allowing the development of a meadow that can provide ecological and economic benefits in terms of ecosystem services.

Appears in: EDULEARN21 Proceedings Publication year: 2021Pages: 1174-1179ISBN: 978-84-09-31267-2ISSN: 2340-1117doi: 10.21125/edulearn.2021.0296Conference name: 13th International Conference on Education and New Learning TechnologiesDates: 5-6 July, 2021Location: Online Conference

Anthropogenic heavy metal pollution is an important health issue in urban areas, and therefore rapid and inexpensive monitoring in time and space is desirable. This study aimed (i) to assess the suitability of Tilia cordata leaves as a valuable heavy metal bioindicator, including seasonal changes in concentrations and (ii) to evaluate the use of leaf carbon and nitrogen isotope composition (delta C-13 and delta N-15) as novel indicators of urban heavy metal pollution. Leaves were collected from three different pollution intensity locations (Bilbao, Vitoria, and Muskiz) in the Basque Country (northern Spain). Analysis of leaf heavy metals related to traffic emissions and delta C-13 and delta N-15 determinations were carried out during July-October 2018. Leaf samples from Bilbao, the most populated and traffic-intense location, showed the highest concentration of heavy metals (mainly from polluted air). Additionally, the two urban areas, Bilbao and Vitoria, showed stronger correlation between these heavy metals, indicating a traffic-related source of emissions. The source of contamination (soil or air) in relation to elements and optimal sampling time is discussed herein. On the other hand, Pearson correlation analysis revealed significant trends between leaf delta C-13 and delta N-15 and the studied heavy metals, especially Pb, Cr and Cd, supporting the hypothesis of delta C-13 and delta N-15 as tools to distinguish locations according to their heavy metal pollution levels. To our knowledge, this is the first time that delta C-13 and delta N-15 have been used as monitoring tools in heavy metal pollution and consequently more research is still needed to calibrate this tool through extensive vegetation screening.