Labile, recalcitrant and stable soil organic carbon: comparison of agronomic management in a vineyard of Trentino (Italy)

The intensive exploitation of agricultural land has caused a depletion of soil organic carbon (SOC) and a decline in soil fertility, with a consequent decrease in the productivity of agroecosystems, also contributing to atmospheric GHG emissions. The ability of soil to storage organic carbon (OC) depends on its persistence and susceptibility to decomposition. SOC is generally partitioned into fractions differing in protection mechanisms and in turn decomposability. This study aimed to compare the OC pool repartition in soils managed with three different fertilization practices (mineral – CONV, manure – ORGM and green manure – ORG-GM) during a medium-term trial in vineyard, in order to understand the best solution in increasing C sequestration. The OC fractionation by acid hydrolysis allowed separating three fractions of OC: a labile, quickly mineralizable pool, a recalcitrant pool with a slower turnover and a stable pool protected by microbial attack. The results showed that the periodic application of organic matrices (manure and green manure), although did not increase total OC, enriched the soil along time with readily available OC, thus promoting the release of nutrients. Green manure has also been shown to promote the accumulation of stabilized OC, able to improve the structure of the soil and, therefore, its fertility

A Synthetic Quality Index to Evaluate the Functional Stability of Soil Microbial Communities After Perturbations

[Abstract] Soil stability includes both resistance, the ability to withstand a perturbation or stress, and resilience, the ability to recover to pre perturbation levels. The functional stability of soil microbial communities is of paramount importance for the ecosystem functioning. We investigated the differences in the stability (resistance and resilience) of three enzyme activities (hydrolytic, laccase and peroxidase) in three different forest (holm oak, black pine and beech) soils after addition of PAHs (phenanthrene, pyrene and benzo[a]pyrene) with different molecular weights. Furthermore, we proposed a new soil quality index (MAI) based on the measured enzyme activity values, useful to quantify the ecological impact of soil perturbations (PAH exposure in our case). The degradation rates of different PAHs follow their complexity, slowing with increasing of PAH molecular weight in all soil types. Moreover, we found higher microbial resistance to PAH perturbation in “broad scale” enzyme activity (hydrolase), in respect to the two “narrow-niche” enzyme activities (laccase and peroxidase). The results demonstrate a higher functional stability in soils with a higher content of recalcitrant organic matter (soil under pine), compared to soils with higher content of labile organic matter (soil under holm oak). In particular, laccase activity is less affected by phenanthrene and pyrene addition in soil under pine; peroxidase activity shows a higher resistance and resilience in soil under beech for all PAHs added. Resistance and/or resilience to PAH contamination, observed for hydrolytic functional stability in the three soils, is mainly due to the high diversity of enzymes expressing this type of catalytic activity

An Effective Biomonitor of Potentially Toxic Elements in Marine Ecosystems: The Brown Alga Dictyota spiralis

Coastal marine areas are threatened by different forms of pollution, among which potentially toxic elements (PTEs) represent a primary hazard. In this study, 16 Mediterranean macroalgae colonizing the upper eulittoral and infralittoral zones were studied for their PTE accumulation capabilities in order to identify possible biomonitors that could replace the use of Posidonia oceanica, a protected species. To achieve this objective, macronutrients (Ca, K, Mg, P, S), micronutrients (Cr, Cu, Fe, Mn, Na, Ni, Si, V, Zn) and non-essential elements (Cd, Pb) were analyzed in the thalli of different algal species, the leaves of P. oceanica and in sediments collected from six sampling sites along the Cilento coast (Campania, Italy), all characterized by different anthropogenic pressures. For sediments, a sequential extraction of PTEs to evaluate their bioavailability profile was also carried out together with the analysis of mineralogical composition, particle size distribution, pH and organic matter content. Macrophytes, belonging to different divisions (six Rhodophyta, four Chlorophyta, six Heterokontophyta, one Embryophyta), are characterized by different PTE concentrations, with a few ones being characterized by an even accumulation response toward the different PTEs. One of these, the brown alga Dictyota spiralis, is able to accumulate PTEs in concentrations similar to P. oceanica and provides more accurate concentration gradients, highlighting clear pollution scenarios that were overlooked using P. oceanica only. Therefore, D. spiralis is a useful PTE biomonitor of coastal marine ecosystems and a suitable replacement for P. oceanica, also featuring the possibility of being employed in active biomonitoring applications

Wilson Disease Protein ATP7B Utilizes Lysosomal Exocytosis to Maintain Copper Homeostasis

SummaryCopper is an essential yet toxic metal and its overload causes Wilson disease, a disorder due to mutations in copper transporter ATP7B. To remove excess copper into the bile, ATP7B traffics toward canalicular area of hepatocytes. However, the trafficking mechanisms of ATP7B remain elusive. Here, we show that, in response to elevated copper, ATP7B moves from the Golgi to lysosomes and imports metal into their lumen. ATP7B enables lysosomes to undergo exocytosis through the interaction with p62 subunit of dynactin that allows lysosome translocation toward the canalicular pole of hepatocytes. Activation of lysosomal exocytosis stimulates copper clearance from the hepatocytes and rescues the most frequent Wilson-disease-causing ATP7B mutant to the appropriate functional site. Our findings indicate that lysosomes serve as an important intermediate in ATP7B trafficking, whereas lysosomal exocytosis operates as an integral process in copper excretion and hence can be targeted for therapeutic approaches to combat Wilson disease

Polymer functionalized nanocomposites for metals removal from water and wastewater: An overview

Pollution by metal and metalloid ions is one of the most widespread environmental concerns. They are non-biodegradable, and, generally, present high water solubility facilitating their environmental mobilisation interacting with abiotic and biotic components such as adsorption onto natural colloids or even accumulation by living organisms, thus, threatening human health and ecosystems. Therefore, there is a high demand for effective removal treatments of heavy metals, making the application of adsorption materials such as polymer-functionalized nanocomposites (PFNCs), increasingly attractive. PFNCs retain the inherent remarkable surface properties of nanoparticles, while the polymeric support materials provide high stability and processability. These nanoparticle-matrix materials are of great interest for metals and metalloids removal thanks to the functional groups of the polymeric matrixes that provide specific bindings to target pollutants. This review discusses PFNCs synthesis, characterization and performance in adsorption processes as well as the potential environmental risks and perspectives. (C) 2016 Elsevier Ltd. All rights reserved

On the Capability of the Epigeous Organs of Phragmites australis to Act as Metal Accumulators in Biomonitoring Studies

With a view of shedding light on the accumulation capability of the epigeous organs of common reed (Phragmites australis), employed worldwide in metal biomonitoring, an accumulation study of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn was performed, focusing on leaves belonging to different whorls and culms. To this end, in five sampling sites on the littoral zone of the volcanic Lake Averno (Italy), and in one occasion (autumn) before plant senescence, leaves of different ages and culms were collected and analyzed for metal concentrations. In terms of the suitability for biomonitoring, culms demonstrated poor performances in relation to the low metal accumulation and the difficulties in sampling and processing, whereas leaves proved their effectiveness in highlighting whole plant exposure. Since the accumulation degree of Cr, Cu, Fe and Zn is unaffected by leaf age, the pooling of leaves from different whorls is advisable to improve the representativeness of samplings. This strategy becomes mandatory in the case of Ni, the non-monotonic age-dependent variations of which would affect the derivation of contamination gradients otherwise. For Mn, Cd and Pb, the accumulation patterns strictly dependent on age can instead be exploited in selecting the sensitivity of biomonitoring by focusing on the organs where they are preferentially accumulated: old leaves for Mn and young leaves for Cd and Pb

Lampenflora growth-control: the challenge of the show caves

Show caves are subjected to tourist adaptations, often with negative consequences on the ecological equilibria of the system. Among the worst problems, photosynthetic biofilms, called “lampenflora”, can develop on surfaces due to the artificial lighting system, covering with green patinas every lit rocks, included speleothems, such as the still few known vermiculations. They implement biodeteriorations processes on surfaces, damaging them irreversibly. The aim of this study was to investigate the efficacy of lampenflora growth-control strategies, carried out monthly using chemical (15% hydrogen peroxide2 or commercial bleach) and physical (UV-C) remedies, on surfaces with and without vermiculations. The tests were performed in the tourist trail of the Pertosa-Auletta Cave (southern Italy), lit and frequented by human beings, analyzing, before and after the treatments, the chlorophyll fluorescences (MINI-PAM, Walz), an in situ non-destructive method representing a proxy of the biofilms photosynthetic activities. The results highlighted an evident reduction of the lampenflora photosynthetic activity already after the 1st treatment. Before every actions, the dark-adapted surfaces, with and without vermiculations, displayed Fv/Fm values between 0.766-0.713 and 0.710-0.663, respectively. After chemical treatments, using H2O2 or commercial bleach, the maximal PSII photochemical efficiency was close to 0, showing an almost complete reduction of the photosynthetic activity. Such values have been maintained until the 2nd treatment, in pre- and post phase. After three months without treatments due to the pandemic lockdown closure of the show cave, there was a slight recovery of lampenflora on the surfaces treated with H2O2, immediately stopped after the 3rd treatment. No effect occurred on the surfaces treated with UV-C, probably in relation to the low frequency of treatments (one night) in a month