Response of an agricultural soil to phenanthrene and pentachlorophenol pollution and to different bioremediation strategies

In the last years, a high number of polluting compounds has been released into the environment because of several industrial and/or agricultural activities. In particular, the rapid industrialization of agriculture, expansions in the chemical industry, and the need to generate cheap forms of energy have all resulted in an ever-increasing reliance on anthropogenic organic chemicals and caused the contamination of a significant number of soil environments by xenobiotic compounds with negative, irreversible effects on environmental quality and health. Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated organic compounds (PCB) are surely the most extensively investigated of the chemical pollutants being toxic to many living organisms, including humans, and extensively used for several industrial activities. Because of their low water solubility, stable aromatic ring system, high chlorine content, these compounds have a high persistence in the environment, and may accumulate in food chains and thus have harmful effects on human health. Bioremediation of contaminated sites relies on the metabolic capacities of living organisms to reduce organic pollutants into harmless or, at least, less dangerous compounds. The process can be realized introducing directly into a contaminated system micro-organisms able to consume selectively the target compound (bioaugmentation) or increasing the microbial indigenous population by addition of nutrients in form of organic and/or inorganic fertilizers such as urea, sawdust, compost, manure and biosolids (biostimulation). The evaluation of the effectiveness of a bioremediation process in contaminated soil, however, should not only look at pollutant removal and/or transformation in non toxic end-products but it should also monitor whether and how soil biological functions are affected by and during the process. Studies were performed on an agricultural soil artificially contaminated with phenanthrene (Phe) or pentachlorophenol (PCP), selected as representative of PAHs and PCBs. In a long-term experiment the efficiency of a phenanthrene-degrading microbial culture, the potentiality of compost and dissolved organic matter in soil decontamination, and the dynamics of the main soil biochemical and biological properties were evaluated. The variations of the major physical and chemical properties were also monitored. The efficiency of the different bioremediating approaches was also evaluated against a Phe-aged (2 years) contaminated soil. The obtained results demonstrated that two complex processes occurred simultaneously in the contaminated soil: natural attenuation and ageing. The investigated soil showed an intrinsic capability of degrading Phe and PCP. The addition of a limited dose of compost, as well as the inoculation with a Phe-degrading bacterial culture strongly stimulated and enhanced the attenuation process. Furthermore, several of the soil properties showed differentiated responses to the presence of the Phe, the compost, and/or the exogenous culture. The results obtained with the soil contaminated with phenanthrene and incubated for 2 years supported the occurrence of the ageing process. The impact of PCP on the properties of the soil was the result of opposite effects. The PCP strongly decreased the levels of some biochemical properties that diminished with increasing the incubation time, thus suggesting a depressing effect on the soil micro flora that not recovered from the initial toxic response towards PCP. Conversely, the presence of the contaminant promoted the development of fungal colonies, contributing to its degradation and consequent production of PCP metabolites, considered more toxic than the parent compound. An ageing phenomenon, also favoured by the presence of the dissolved organic matter and leading to the decrease of the extractable PCP, was also hypothesized. The results obtained in this thesis work suggest that soil biological investigations can give information about the intensity and the kind and duration of the effects of pollutants on the metabolic activity of soil. Although the experiments are limited by the laboratory, controlled conditions adopted, they are well suited for measuring the effects of pollution on soil health and to act as a monitoring tool for the decontamination process of a polluted soil. Furthermore, such investigations may be helpful for further studies aimed at validating and extrapolating the data to natural situations

Proteomica del prodotto fresco e trasformato.

Analisi proteomica è stata condotta su pomodori da industria ottenuti in convenzionale e in biologico per evidenziare diversità nel proteoma

Proprietà biochimiche e biologiche dei suoli

E' stata studiata la fertilità biochimica e biologica di suoli agricoli coltivati a pomodoro in regime biologic

Biochar based remediation of water and soil contaminated by phenanthrene and pentachlorophenol

Phenanthrene (Phe) and pentachlorophenol (PCP) are classified as persistent organic pollutants and represent serious concern for the environment as they are toxic and ubiquitous. Biochar based remediation is an emerging technology used in water and soil contamination. In this study we used poplar (BP) and conifer (BC) biochars to remediate water and soil contaminated by Phe and PCP. BP and BC were able to remove completely either Phe or PCP from contaminated water within one to three days. When biochar was confined in a porous membrane, BC and BP maintained their sorption efficiency for several remediation cycles. However, in these conditions BC allowed faster Phe removal. In soil remediation experiments, addition of two biochar rates, i.e. 2.5 and 5 mg g−1, strongly reduced Phe extractability (up to 2.7% of the initially added Phe with the larger BC dose). This was similar to the behavior observed when compost was applied in order to verify the role of soil organic matter in the fate of both contaminants. PCP extractability was reduced only up to 75% (in average) in all samples including those with compost amendment. Only larger amount of biochar (20 and 50 mg g−1) allowed reduction of the extractable PCP and nullified phytotoxicity of the contaminant

Effetto dell'impiego di micorrize su proprietà biochimice del suolo e diponibilità dei nutrienti

La biomassa microbica e gli enzimi del suolo sono considerati dei validi bioindicatori della qualità e in particolare della fertilità di un suolo giacché sensibili alla variazione dei parametri del suolo, correlati con le funzioni del suolo e facilmente misurabili. Nel progetto MICOMAIS sono state prese in esame attività enzimatiche strettamente correlate all’attività dei microrganismi (deidrogenasi e FDA idrolasi), alla degradazione della sostanza organica (beta-glucosidasi e invertasi) e al ciclo dell’azoto (ureasi, deamminasi, ammonio monossigenasi, nitratoreduttasi) e del fosforo (fosfatasi), sia nel suolo bulk che in quello rizosferico, così da comprendere anche la disponibilità dei nutrienti nelle tesi con o senza micorrizazione e a diverse dosi di fertilizzanti minerali

Organic amendments as sustainable tool to recovery fertility in intensive agricultural systems

Intensive agriculture is a farming system characterised by a large use of inputs, causing a large pressure on the environment. As peculiar and efficient example of intensive agriculture cultivation under plastic tunnels provides several advantages for farmers due to improvement of microclimatic conditions coupled with a relatively low investment costs. In the Mediterranean Basin such cultivation systems reach about 200,000 ha mainly in Spain, Turkey, Italy, and Morocco. As downside, intensive agriculture negatively affects soil fertility principally because of a loss in soil organic matter. Sustainable practices providing organic amendments could be a useful tool to maintain or increase organic matter content in agricultural soils, preserving and improving soil fertility. An improved knowledge of management factors affecting soil quality is crucial to plan farming systems that effectively maintain soil fertility. Therefore, this review focuses on the potential value of organic amendments in the recovery of soil fertility, in particular in sites under plastic cover intensive farming system. Following a brief overview of the effects of intensive agriculture on soil, the review describes various organic amendments used in agriculture and their benefits on soil fertility, to conclude with the need, in the future researches, to identify organic amendments able to maximize a recovery of soil fertility