RESUMO
A total of 476 European isolates (310 Cryptococcus neoformans var. grubii, 150 C. neoformans var. neoformans, and 16 C. gattii species complex) from both clinical and environmental sources were analyzed by multi-locus sequence typing. Phylogenetic and population genetic analyses were performed. Sequence analysis identified 74 sequence types among C. neoformans var. neoformans (VNIV), 65 among C. neoformans var. grubii (56 VNI, 8 VNII, 1 VNB), and 5 among the C. gattii species complex (4 VGI and 1 VGIV) isolates. ST23 was the most frequent genotype (22%) among VNI isolates which were mostly grouped in a large clonal cluster including 50% of isolates. Among VNIV isolates, a predominant genotype was not identified. A high percentage of autochthonous STs were identified in both VNI (71%) and VNIV (96%) group of isolates. The 16 European C. gattii species complex isolates analyzed in the present study originated all from the environment and all belonged to a large cluster endemic in the Mediterranean area. Population genetic analysis confirmed that VNI group of isolates were characterized by low variability and clonal expansion while VNIV by a higher variability and a number of recombination events. However, when VNI and VNIV environmental isolates were compared, they showed a similar population structure with a high percentage of shared mutations and the absence of fixed mutations. Also linkage disequilibrium analysis reveals differences between clinical and environmental isolates showing a key role of PLB1 allele combinations in host infection as well as the key role of LAC1 allele combinations for survival of the fungus in the environment. The present study shows that genetic comparison of clinical and environmental isolates represents a first step to understand the genetic characteristics that cause the shift of some genotypes from a saprophytic to a parasitic life style.
Assuntos
Cryptococcus gattii/genética , Cryptococcus neoformans/genética , Genótipo , Filogenia , Animais , Microbiologia Ambiental , Europa (Continente) , Genética Populacional , Humanos , Região do Mediterrâneo , Tipagem de Sequências Multilocus , Técnicas de Tipagem MicológicaRESUMO
BACKGROUND: The use of reclaimed dredged sediments as growing media may offer a profitable alternative to their disposal as a waste and at the same time meets the need of peat-substitute substrates in horticulture. When sediments are reused to cultivate food crops, issues related to human health rise due to potential accumulation of contaminants in the product. This pilot study aimed at verifying the suitability of a reclaimed dredged port sediment, used pure or mixed with peat, as a growing medium for lettuce cultivation. RESULTS: The pure sediment caused a reduction in crop yield, probably due to its unsuitable physical properties, whereas the mixture sediment-peat and pure peat resulted in the same yield. Although the sediment contained potentially phytotoxic heavy metals and some organic pollutants, no symptoms of plant toxicity were noted. Besides, no organic contaminants were detected in lettuce heads, and heavy metals amounts were not hazardous for consumers. Conversely, plants grown in the sediment were particularly rich in minerals like Ca, Mg and Fe, and showed higher concentrations of organic acids and antioxidants. CONCLUSION: The use of the sediment as a growing medium for lettuce was shown to be safe for both inorganic and organic contaminants. Nevertheless, considering crop yield results, the mixture of the sediment with other materials is recommended in order to produce a substrate with more suitable physicochemical properties for vegetable cultivation. © 2019 Society of Chemical Industry.
Assuntos
Produção Agrícola/métodos , Sedimentos Geológicos/química , Lactuca/crescimento & desenvolvimento , Verduras/crescimento & desenvolvimento , Biodegradação Ambiental , Produção Agrícola/instrumentação , Inocuidade dos Alimentos , Lactuca/química , Lactuca/metabolismo , Metais Pesados/análise , Minerais/análise , Minerais/metabolismo , Projetos Piloto , Verduras/química , Verduras/metabolismoRESUMO
The sediments dredged from a waterway and decontaminated through a phytoremediation process have been used as substrates alternatively to the traditional forest nursery substrate for pot productions of holm oak (Quercus ilex L.) planting stocks. The substrates, made by mixing decontaminated sediments to agricultural soil at different degrees, were tested in order to evaluate their suitability as growth substrates. The experiment was carried out at the nursery of the Department of Agricultural, Food and Forestry Systems of the University of Florence (Italy). The experimental design consisted of four randomized blocks with six pots as replicates for each of the following treatments: 100% sediments, 66% sediments, 33% sediments, 100% agronomic soil and 100% traditional peat based substrate. In each pot, one holm oak acorn was seeded. Germination and both physiological and morphological traits of the seedlings were analysed during and at the end of the first growing season. Holm oak grown in phytoremediated sediments at higher concentrations showed germination levels comparable to those in the traditional substrate, and survival capacity (especially in 66% sediments) slightly higher than in 100% soil. Physiological performance of seedlings resembled that on the traditional substrate which required the addition of fertilizer, at least for the first growing season. Seedlings grown in mixed substrates with higher sediment concentrations occasionally showed better photosynthetic capacity with improved connectivity between the units of the photosystem II. At the end of the first growing season, height as well as the number of growth flushes of the seedlings grown in sole sediment or soil-sediment substrates were similar to what generally is observed for forest nursery stock of Quercus spp.. Regarding the root-system articulation and growth in depth, results in the mixed substrates were comparable to those for seedlings grown in the traditional forest nursery media, and higher than seedlings grown in 100% agronomic soil. According to our results, the reclamation of dredged sediments can provide appropriate nursery substrate for germination beds for forestry species.
Assuntos
Agricultura Florestal , Sedimentos Geológicos , Árvores , Biodegradação Ambiental , Florestas , Itália , Quercus , Plântula , SoloRESUMO
Fundamental niche prediction of Cryptococcus neoformans and Cryptococcus gattii in Europe is an important tool to understand where these pathogenic yeasts have a high probability to survive in the environment and therefore to identify the areas with high risk of infection. In this study, occurrence data for C. neoformans and C. gattii were compared by MaxEnt software with several bioclimatic conditions as well as with soil characteristics and land use. The results showed that C. gattii distribution can be predicted with high probability along the Mediterranean coast. The analysis of variables showed that its distribution is limited by low temperatures during the coldest season, and by heavy precipitations in the driest season. C. neoformans var. grubii is able to colonize the same areas of C. gattii but is more tolerant to cold winter temperatures and summer precipitations. In contrast, the C. neoformans var. neoformans map was completely different. The best conditions for its survival were displayed in sub-continental areas and not along the Mediterranean coasts. In conclusion, we produced for the first time detailed prediction maps of the species and varieties of the C. neoformans and C. gattii species complex in Europe and Mediterranean area.
Assuntos
Microambiente Celular/fisiologia , Cryptococcus gattii/crescimento & desenvolvimento , Cryptococcus neoformans/crescimento & desenvolvimento , Microbiologia Ambiental , Microbiologia do Solo , Criptococose/microbiologia , Cryptococcus gattii/metabolismo , Cryptococcus neoformans/metabolismo , Europa (Continente) , Região do Mediterrâneo , Estações do Ano , Solo/química , Tempo (Meteorologia)RESUMO
We evaluated the potential of a phytoremediated sediment (TR) dredged from maritime port as peat-free growth substrate for seven ornamental plants, in comparison with an untreated sediment (NT), in a greenhouse experiment. The studied plants were Quercus ilex, Photinia x fraseri, Viburnum tinus, Cistus albidus, Raphiolepis indica, Westringia fruticosa and Teucrium fruticans. Plant growth was monitored for ten months, and the changes in the physico-chemical properties, toxicity, microbial biomass and enzyme activities involved in the C, P and N cycles were also monitored during the plant growth period. The results showed that the studied ornamental plants could grow on both NT and TR sediments, but that the growth was higher on TR sediment. The plant growth induced changes in the sediment chemical functional groups, with clear separation between NT and TR sediments for each of the studied plant. Microbial biomass and enzyme activities significantly increased during the plant growth, more in TR than in NT sediment. Toxicity was detected in NT sediments during the plant growth whereas it was not observed in NT sediments during the whole growth period. We concluded that phytoremediation converted the dredged maritime sediments into suitable substrates for growing ornamental plants, and that the re-use by plant nursery industry can be a sustainable management and valorization for remediated sediments.
Assuntos
Biodegradação Ambiental , Sedimentos Geológicos , Desenvolvimento Vegetal , Biomassa , Cistus/crescimento & desenvolvimento , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Photinia/crescimento & desenvolvimento , Quercus/crescimento & desenvolvimento , Solo , Poluentes do Solo/química , Poluentes do Solo/toxicidade , Viburnum/crescimento & desenvolvimentoRESUMO
When canals and harbours are dredged, huge amount of polluted sediments has to be stocked and transported to the landfill with incredibly high costs of management. Among the remediation techniques for the reclamation of polluted sediments and soils, phytoremediation represents a sustainable and effective technique though still not fully promoted or commercialized. In this study we have tested the suitability for plant nursing of a substrate resulting from sediments dredged from a canal and treated with phytoremediation. The experiment was set up in 2014. It aimed to test the physical, chemical and hydrological characteristics of two mixes of remediated sediments and agronomic soil (at 33% and 50% by volume) compared to control soil (100% agronomic soil), and to assess the growth of three ornamental species (Viburnum tinus L., Photinia x fraseri var. red robin, Eleagnus macrophylla Thunb.) together with the suitability for root balling. The mixed substrates produced good results in terms of water drainage, and were similar to the control in terms of soluble nutrients, guaranteeing and enhancing the aboveground and belowground growth of all the three species, especially V. tinus. In contrast, mixed substrates impaired root ball compaction with root ball breakage observed especially in 50% sediment/soil mix. Therefore, the use of remediated sediments in plant nursery can be limited to specific productions or practices.
Assuntos
Biodegradação Ambiental , Poluentes do Solo , Sedimentos Geológicos , Plantas , SoloRESUMO
In order to elucidate the distribution of Cryptococcus neoformans and C. gattii in the Mediterranean basin, an extensive environmental survey was carried out during 2012-2015. A total of 302 sites located in 12 countries were sampled, 6436 samples from 3765 trees were collected and 5% of trees were found to be colonized by cryptococcal yeasts. Cryptococcus neoformans was isolated from 177 trees and C. gattii from 13. Cryptococcus neoformans colonized 27% of Ceratonia, 10% of Olea, Platanus and Prunus trees and a lower percentage of other tree genera. The 13 C. gattii isolates were collected from five Eucalyptus, four Ceratonia, two Pinus and two Olea trees. Cryptococcus neoformans was distributed all around the Mediterranean basin, whereas C. gattii was isolated in Greece, Southern Italy and Spain, in agreement with previous findings from both clinical and environmental sources. Among C. neoformans isolates, VNI was the prevalent molecular type but VNII, VNIV and VNIII hybrid strains were also isolated. With the exception of a single VGIV isolate, all C. gattii isolates were VGI. The results confirmed the presence of both Cryptococcus species in the Mediterranean environment, and showed that both carob and olive trees represent an important niche for these yeasts.
Assuntos
Cryptococcus gattii/isolamento & purificação , Cryptococcus neoformans/isolamento & purificação , Microbiologia Ambiental , Árvores/microbiologia , Cryptococcus gattii/classificação , Cryptococcus gattii/genética , Cryptococcus neoformans/classificação , Cryptococcus neoformans/genética , Genótipo , Região do Mediterrâneo , Tipagem Molecular , Técnicas de Tipagem MicológicaRESUMO
Sludge stabilisation and mineralisation during periods of operation between 10 and 21 years were investigated in three different systems receiving sludge from urban wastewater treatment plants situated in Denmark. Samples were taken along the entire profiles, in order to compare the effectiveness of the sludge stabilisation process. Particular attention was given to the stabilisation process occurring within the reed beds; in fact, parameters correlated to biochemical properties of organic sludge matter were determined. Statistical procedures were used to evaluate how the biochemical processes influence the quality of sludge organic matter. The level of total organic carbon and total nitrogen had a similar trend along the profile: their concentration decreased with increasing depth, reaching very low levels at the deepest layers. The same trend was also observed for the water-soluble carbon, N-NH(3), ß-glucosidase and urease activities, and hydrolytic enzymes linked to C and N cycles: their values decreased dramatically with increasing depth, meaning that the level of mineralisation of the organic matter was higher in the deepest layers. The determination of extracellular enzymes bound to humic substances and humic carbon permitted evaluation of the stabilisation of organic sludge matter, and also allowed individuation of the ways in which the sludge was stabilised, in terms of mineralisation and humification of the organic matter.
Assuntos
Esgotos/química , Áreas Alagadas , DinamarcaRESUMO
In the present investigation, a phytoremediation process with a combination of different plant species (Populus nigra (var.italica), Paulownia tomentosa and Cytisus scoparius), and natural growing vegetation has been proposed at real-scale (10.000 m(2)) to bioremediate and functionally recover a soil historically contaminated by heavy metals and hydrocarbons. In the attempts to assess both effectiveness and evolution of the remediation system towards a natural soil ecosystem, besides the pollution parameters, also parameters describing the efficiency of the microbiological components (enzyme activities), were investigated. In 3 years, the total content of hydrocarbons and heavy metals in soil decreased with time (40 % and 20-40 %, respectively), reaching concentrations under the limit of National legislation and making the site suitable for environmental reusing. The reduction in pollutants was probably the reason of the increase in dehydrogenase (indicator of overall microbial activity), ß-glucosidase and phosphatase activities, enzymes related to C and P cycles, respectively. However, this trend was obviously due also to the increase of chemical nutrients, acting as substrate of these enzymes. Moreover, a phytotest carried out with Raphanus sativus, showed, after 3 years, a significant increase in percentage of plant growth, confirming a reduction in soil toxicity and an improvement in soil nutritional state. Therefore, this phytoremediation system seems very promising to perform both decontamination and functional recovery of a polluted soil at real-scale level.
Assuntos
Cytisus/metabolismo , Recuperação e Remediação Ambiental/métodos , Hidrocarbonetos/metabolismo , Magnoliopsida/metabolismo , Metais Pesados/metabolismo , Populus/metabolismo , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Cytisus/química , Hidrocarbonetos/análise , Magnoliopsida/química , Metais Pesados/análise , Populus/química , Solo/química , Poluentes do Solo/análiseRESUMO
In this study, results about sludge stabilization in reed bed systems (RBSs) after the entire period of operation in two different systems situated in Denmark (Helsinge 42,000 population equivalent (p.e.) - 10 years) and in Italy (La Fontina, 30,000 p.e. - 6 years) were presented. In order to evaluate the process of sludge stabilization, parameters that highlighted the biochemical and chemico-structural properties of organic sludge matter have been determined. The level of total and soluble nutrients, and enzyme activities, parameters related to overall microbial activity, showed that stabilization of the sludge similarly occurred in both RBSs, even though in different landscape ecosystems. The chemical-structural characterization of sludge organic matter highlighted how the processes of stabilization have occurred satisfactorily in both RBSs; in fact, significant levels of pyrolytic indices for mineralization and humification were reached. The successful stabilization of organic matter occurred in both RBSs and was confirmed by the absence of Escherichia coli, and also by the results of organic compounds (polycyclic aromatic hydrocarbons, linear alkyl benzene sulfonates, nonylphenol ethoxylates, di-2-ethylhexyl-phthalate) and heavy metals.
Assuntos
Esgotos , Eliminação de Resíduos Líquidos/métodos , Alcanossulfonatos/metabolismo , Biodegradação Ambiental , Dinamarca , Enzimas/metabolismo , Escherichia coli , Etilenoglicóis/metabolismo , Substâncias Húmicas , Itália , Metais Pesados/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Análise de Componente Principal , Esgotos/microbiologiaRESUMO
Two plant species (Paulownia tomentosa and Cytisus scoparius), earthworms (Eisenia fetida), and organic matter (horse manure) were used as an ecological approach to bioremediate a soil historically contaminated by heavy metals and hydrocarbons. The experiment was carried out for six months at a mesoscale level using pots containing 90 kg of polluted soil. Three different treatments were performed for each plant: (i) untreated planted soil as a control (C); (ii) planted soil + horse manure (20:1 w/w) (M); (iii) planted soil + horse manure + 15 earthworms (ME). Both the plant species were able to grow in the polluted soil and to improve the soil's bio-chemical conditions, especially when organic matter and earthworms were applied. By comparing the two plant species, few significant differences were observed in the soil characteristics; Cytisus scoparius improved soil nutrient content more than Paulownia tomentosa, which instead stimulated more soil microbial metabolism. Regarding the pollutants, Paulownia tomentosa was more efficient in reducing the heavy metal (Pb, Cr, Cd, Zn, Cu, Ni) content, while earthworms were particularly able to stimulate the processes involved in the decontamination of organic pollutants (hydrocarbons). This ecological approach, validated at a mesoscale level, has recently been transferred to a real scale situation to carry out the bioremediation of polluted soil in San Giuliano Terme Municipality (Pisa, Italy).
Assuntos
Recuperação e Remediação Ambiental/métodos , Hidrocarbonetos/análise , Plantas/química , Poluentes do Solo/análise , Solo/química , Animais , Biodegradação Ambiental , Itália , Esterco , Metais Pesados , OligoquetosRESUMO
The semi-arid Mediterranean region, characterized by long dry periods followed by heavy bursts of rainfall, is particularly prone to soil erosion. The main goal of this study is to evaluate the soil quality under different practices of bio-physical amelioration which involve the soil-plant system (almond trees) and microorganism-manure. This study, carried out in the South of Italy (Basilicata Region- Pantanello farm), considered two types of fertilization (mineral and organic) and three slope gradients (0, 2 and 6%), in order to evaluate the effects of management practices in resisting soil erosion. Chemical (organic carbon and nitrogen), physical (soil shrinkage and bulk density) and biochemical (dehydrogenase activity and hydrolytic enzyme activities) parameters were selected as markers to follow agro-ecological changes with time. The organic treatment affected soil microbiological and physico-chemical properties by increasing soil nutrient availability, microbial activity, and improving soil structure. The consistently higher values of the hydrolytic enzyme activities (ß-glucosidase, phosphatase, urease and protease) often observed in the presence of plants and on the 0 and 2% slopes, suggested the stimulation of nutrient cycles by tree roots, which improve the conditions for soil microorganisms in carrying out their metabolic activity. In the 6% slope and, in particular, in the mineral fertilizer treatment, soil metabolism was lower as suggested by the dehydrogenase activity which was 50% lower than that found in the 0 and 2% slopes, this seemed to be related to a slowdown in the nutrient cycling and organic carbon metabolism. However, on this slope, in both mineral and organic treatments, a significant stimulation of hydrolytic enzyme activities and an improvement of soil structure (reduction of bulk density of about 10% and increase in total shrinkage from 20 to 60%) were observed with plants compared to the control soil. The combination of organic fertilization and almond trees resulted effective, also in the highest slope, in mitigating the degradation processes through the improvement of chemico-nutritional, biochemical and physical soil properties.
Assuntos
Fertilizantes , Agricultura Orgânica/métodos , Prunus/fisiologia , Solo , Carbono/análise , Enzimas/metabolismo , Itália , Esterco/microbiologia , Nitrogênio/análise , Oxirredutases/metabolismo , Raízes de Plantas/metabolismo , Melhoria de Qualidade , Solo/químicaRESUMO
The aim of this study was to evaluate the effectiveness of a landfarming process (LP) in recovering sediments at different biodegradation phases: phytoremediated dredged sediments (PDS) and fresh dredged sediments (FDS). The PDS landfarming was applied to (1) reduce residual contamination and (2) improve the biological activities in order to obtain a decontaminated matrix rich in organic matter and enzymatic activity to be reused as agronomic substrate. In 3 months of LP, a microbial activity stimulation (from 7 to 48%) and a decrease in organic contamination (about 15%) were recorded. In addition, no phytotoxicity and the content in total organic carbon and nitrogen make the sediments suitable to be reused in agriculture. The FDS landfarming was carried out to (1) reduce water content, (2) transform the organic matter into a more stable form, and (3) decrease organic contaminant level. Five months of LP led to a considerable reduction in water content (40%) and to the activation of microbial biomass metabolism (from 4 to 50 times higher), which achieved proper mineralization of organic matter and contaminants (polycyclic aromatic hydrocarbons near to zero and a total petroleum hydrocarbon reduction of about 60%). The LP also enhanced the stoichiometric ratios of nutrients and enzymes. In conclusion, the LP was a promising and economical methodology to improve the physical, chemical, and biological properties of polluted sediments at different biodegradation phases, creating a substrate ready for several environmental applications. Notably, the PDS resulted appropriate for agricultural use and FDS for civil applications.
Assuntos
Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Biodegradação Ambiental , Sedimentos Geológicos , Hidrocarbonetos , Petróleo/análise , Hidrocarbonetos Policíclicos Aromáticos/análiseRESUMO
BACKGROUND: Olive mill wastewaters (OMWW) contain a high recalcitrant organic load and an associated toxicity that make their treatment necessary before environmental application. The aim of this study was to evaluate the feasibility of promoting the valorization and reducing the phytotoxicity of OMWW through a pre-composting process together with straw-chip bulking materials followed by the application of earthworms (Eisenia fetida) in the presence of oat seedlings (Avena sativa L.) seedlings. RESULTS: After 3 months, the pre-composted material showed properties similar to a partially digested compost with some significant amelioration of chemical-physical and biochemical properties. The application of earthworms permitted a significant decrease in chemical (total organic carbon, water-extractable organic carbon, total nitrogen) and biological parameters (dehydrogenase enzyme activity), and an increase in humic substances and available nitrogen forms. In the presence of plants a higher C/N ratio and a lower content of nitrates were observed. In addition, the reduction in phenolic compounds observed in treatments with earthworms caused a decrease in phytotoxicity by about 50% with respect to the pre-composted material, which results in an increase in germination index. CONCLUSION: The utilization of earthworms, in particular in the presence of plants, may be an ecologically sound and economically feasible technology to obtain a non-toxic, high-value product useful for agricultural purposes.
Assuntos
Biodegradação Ambiental , Resíduos Perigosos , Substâncias Húmicas/análise , Resíduos Industriais , Oligoquetos , Óleos de Plantas , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise , Animais , Carbono/análise , Nitratos/análise , Nitrogênio/análise , Azeite de Oliva , Oxirredutases , Fenóis/análise , Óleos de Plantas/toxicidade , SoloRESUMO
The disposal of olive oil mill wastewaters (OMW) represents a substantial environmental problem in Italy. A vermicompost process could be an alternative and valid method for the management of OMW. In a laboratory experiment, the OMW were absorbed onto a ligno-cellulosic solid matrix and 30 adult earthworms of Eisenia fetida specie were added. The experiment was carried out for 13 weeks. The number of earthworms increased throughout the experimental period and after 2 weeks about 90% of the earthworms had become sexually mature. The decrease in total organic carbon (about 35%), C : N ratio (from 31.2 to 12.3) and biochemical parameters (hydrolytic enzymes averagely 40% and dehydrogenase 23%), and the increase in humification rate (pyrophosphate extractable carbon (PEC) from 17.6 to 33.3 mg g(-1), and PEC : water-soluble carbon from 1.76 to 2.97) indicated the mineralization and the stabilization of organic matter at the end of the vermicomposting process. At the end of the experiment, the extracellular beta-glucosidase, phosphatase, urease and protease activities, measured in the pyrophosphate extract of the vermicompost, were found to be always higher or equal to that measured at the beginning of the vermicomposting process, suggesting that the enzymes bound to humic matter resisted biological attack and environmental stress. Moreover, the results obtained from the phyto-test showed that the OMW lose their toxicity and stimulate plant germination and growth.
Assuntos
Biodegradação Ambiental , Resíduos Industriais/prevenção & controle , Óleos de Plantas , Solo , Poluentes da Água , Animais , Conservação dos Recursos Naturais/métodos , Oligoquetos/metabolismo , Azeite de Oliva , Desenvolvimento VegetalRESUMO
The purpose of this study was to monitor and model indicators of soil contamination, organic matter evolution and biochemical processes involved in a long-term phytoremediation process. Populus nigra L., Paulownia tomentosa Steud., Cytisus scoparius L. and natural vegetation were used in differently contaminated areas (high, medium and low levels of contamination). Parameters indicating contamination (total petroleum hydrocarbons (TPH) and heavy metals) and agronomic (C, N and P) and functional (enzyme activities) soil recovery were monitored for 3.5 years. Three subareas with different levels of contamination (high, medium and low) were identified according to the Nemerow Index. A considerable decrease in TPH (52% on average) over time in the whole site was measured, while the metal reduction was only of about 22% at surface level. A stimulation in metabolic soil processes and improvement in the chemical quality of the soil was also observed throughout the experimental site. Statistical analysis modelling showed that the contaminant content decreased following a one-phase decay model, while the dramatic increase in enzyme activities could be represented by an exponential growth equation. On the basis of our data, it is possible to conclude that the initial contamination level affected neither the decontamination process nor the improvement in soil quality, which occurred similarly in the three different contaminated areas.
Assuntos
Biodegradação Ambiental , Metais Pesados/metabolismo , Poluentes do Solo/metabolismo , Hidrocarbonetos/análise , Lamiales/metabolismo , Metais Pesados/análise , Petróleo/análise , Populus/metabolismo , Solo/química , Microbiologia do Solo , Poluentes do Solo/análiseRESUMO
A harbour sediment, previously remediated, was tested for soilless strawberry cultivation (Camarosa and Monterey cultivars), as an innovative, cost-effective and environment-friendly approach of sediment management. Sediments were tested as such (TS100) and mixed 1/1 (v/v) with a peat-based commercial substrate (TS50), using the peat-based medium as control (TS0). Substrates were characterized for some physicochemical properties (e.g. density, porosity and water capacity). Minerals (P, Ca, K, Na and Fe), heavy metals (Cu, Zn, Mn, Ni, Cr, Pb and Cd), aliphatic hydrocarbons (Câ¯>â¯12), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dibenzodioxins and dibenzofurans were analysed in substrates and fruits. Sugars and organic acids, including the ascorbic, were also determined in fruits, as quality indicators. Notwithstanding remediation, sediments showed concentrations of Zn (206â¯mgâ¯kg-1), Câ¯>â¯12 (86â¯mgâ¯kg-1) and PAHs (47â¯mgâ¯kg-1) exceeding the limits established by the Italian L.D. 152/2006, regulating the contamination of soil in green areas, thus making its relocation in the environment not permitted as such. No evidence of fruit contamination by Cr, Pb and Cd was highlighted. Moreover, Cu, Zn and Ni fruit concentrations were comparable among treatments. Conversely, Mn showed statistically higher concentrations in TS0 fruits (56-57â¯mgâ¯kg-1) compared to those grown in sediment-based substrates (8-20â¯mgâ¯kg-1). Among organic contaminants, only dioxin-like PCBs were determined in fruits, at toxic equivalent concentrations fourfold lower than the limit established by the European Union. TS100 fruits showed a yield reduction from 40 to 70% for Camarosa and Monterey, but higher sugar and ascorbic acid contents.
Assuntos
Produtos Agrícolas/normas , Monitoramento Ambiental , Fragaria/metabolismo , Frutas/química , Sedimentos Geológicos/química , Produtos Agrícolas/química , Produtos Agrícolas/crescimento & desenvolvimento , Fragaria/química , Itália , Metais Pesados/análise , Minerais/análise , Bifenilos Policlorados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes do Solo/químicaRESUMO
The aim of this study was to characterize soils contaminated by different levels of heavy metals and hydrocarbons (Madonna Dell'Acqua, Pisa, Italy). The soils were chemically and biochemically analysed by measuring the standard chemical properties and some enzyme activities related to microbial activity (dehydrogenase activity) and the soil carbon cycle (total and extracellular beta-glucosidase activities). The metabolic capacities of soil microorganisms to degrade hydrocarbons through catechol 2,3-dioxygenase were also described. The microbial diversity of contaminated and uncontaminated soils was estimated by denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA sequences. The PCR/single-strand conformation polymorphism (PCR/SSCP) method was used to estimate the genetic diversity of PAH-degrading genes in both contaminated and uncontaminated soils. A greater bacterial diversity and lower catechol 2,3-dioxygenase activity was detected in unpolluted soils. The complexity of the microbial community (Shannon and Simpson indices) as well as the dehydrogenase soil activity negatively correlated with contamination levels. The greatest PAH-degrading gene diversity and the most intense catechol 2,3-dioxygenase activity were found in the soils with the highest levels of hydrocarbons. Heavy metals and hydrocarbon pollution has caused a genetic and metabolic alteration in microbial communities, corresponding to a reduction in microbial activity. A multi-technique approach combining traditional biochemical methods with molecular-based techniques, along with some methodological improvements, may represent an important tool to expand our knowledge of the role of microbial diversity in contaminated soil.
Assuntos
Bactérias/metabolismo , Hidrocarbonetos/análise , Metais Pesados/análise , Microbiologia do Solo , Poluentes do Solo/análise , Bactérias/classificação , Bactérias/enzimologia , Sequência de Bases , Primers do DNA , Eletroforese em Gel de Poliacrilamida , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita Simples , Especificidade da EspécieRESUMO
Sediments dredged by an industrial port, slightly contaminated by heavy metals and petroleoum hydrocarbons, were phytoremediated and used as peat-free growing media for the red robin photinia (Photinia x fraseri L.). Plants were grown on sediment only (S), sediment mixed with composted pruning residues (S + PR), sediment fertilized with controlled release fertilizers (S + F) and peat-based growing media as control (C). Plant elongation and dry weight, leaf contents of chlorophyll, malondialdehyde (MDA), macronutrients and heavy metals were determined at the end of one growing season. Environmental impact related to the use of sediment-based as compared to peat-based growing media was assessed by the Life Cycle Analysis (LCA). Sediment-based growing media presented significantly higher bulk density, pH and electrical conductivity values, lower C and N contents, and significantly higher total and available P. Red robin photinia grown on S + F growing media showed morphological and chemical parameters similar to those of control plants (C), whereas plants grown on S and S + PR showed lower growth. Leaf concentration of nutrients and heavy metals varied depending on the considered element and growing media, but were all within the common values for ornamental plants, whereas the highest MDA concentrations were found in plants grown on traditional growing media. The LCA indicated the use of sediments as growing media reduced the C footprint of ornamental plant production and the contribute of growing media to the environmental impact per produced plant. We concluded that sediments phytoremediation and use in plant nursery is a practical alternative re-use option for dredged sediments.