Accumulation of Heavy Metals in Vegetables from Agricultural Soils

This study analyzed the heavy metals in vegetables cultivated in private gardens in Bregu i Matit, an important agricultural area in the NW Albania.The plant and soil samples taken from irrigated and non-irrigated fields in this area were analyzed for the concentrations of Cd, Cu, Zn, Pb and Ni using atomic absorption spectroscopy (AAS), after extraction by HNO3 and H2O2.The transfer factors (TF) were used to evaluate the risk of metal transfer from soil to plant and the FAO/WHO safe limits to assess the potential hazards of heavy metals to human health. The ranges of heavy metal concentrations \ub1 standard deviation in vegetable samples were (mg kg-1): Cu 2.98-12.90 (\ub13.08), Ni 4.82-35.79 (\ub17.68), Zn Zn > Cu > Ni > Pb. The TF values indicate that only Cd was accumulated in plants.The contents of Cd in three vegetable samples, Pb in four samples, and Cu in one sample were above the safe limits set by the FAO/WHO for heavy metals in foods and vegetables indicating that consumption of vegetables grown in the studied soils could be dangerous to human health

METHANE AND CARBON DIOXIDE FLUXES FROM LIMONIUM RESIDUES DECOMPOSITION IN SALTMARSH SOILS: EFFECTS OF TIDE REGIME

The flooding regime of saltmarshes strongly affects organic matter mineralisation, representing a unique situation where oxygen diffusion is either impeded by submersion or favoured by retreating water in regular cycles within the same day. Decomposition of Limonium vulgare Mill. residues in saltmarsh soils was evaluated measuring CO2 and CH4 emissions. Four different saltmarshes from the Grado Lagoon (Northern Adriatic Sea) were investigated. Soils were characterised by a similar vegetation (Sarcocornietea class) and similar high coverage of L. vulgare (70-75%) but differed in redox potential, texture and organic carbon content. Hydromorphic conditions were reproduced in mesocosms, and soils were incubated under fully aerobic, fully anaerobic and transient (6 hours cycles) tidal states. Partially decomposed litter (leaves) of L. vulgare was added and decomposition processes were monitored through CO2 and CH4 emissions. Larger CO2 emissions were measured under aerobic conditions, in particular in soil samples with coarse texture. Fully anoxic and tidal regimes showed a similar behaviour. On the contrary, CH4 emissions were less dependent upon flooding, showing only slightly larger values under completely submerged conditions. Larger CH4 emissions have been obtained in fine textured soils. Soil organic matter content also influenced gas emissions: larger values corresponded to higher emissions of both CO2 and CH4

Bioaccumulation of polycyclic aromatic hydrocarbons and survival of earthworms (Eisenia andrei) exposed to biochar amended soils

Biochar has a charcoal polycyclic aromatic structure which allows its long half-life in soil, making it an ideal tool for C sequestration and for adsorption of organic pollutants, but at the same time raises concerns about possible adverse impacts on soil biota. Two biochars were tested under laboratory-controlled conditions on Eisenia andrei earthworms: a biochar produced at low temperature from wine tree cuttings (WTB) and a commercial low tar hardwood lump charcoal (HLB). The avoidance test (48-h exposure) showed that earthworms avoid biochar-treated soil with rates higher than 16 t ha 121 for HLB and 64 t ha 121 for WTB. After 42 days, toxic effects on earthworms were observed even at application rates (100 t ha 121) that are generally considered beneficial for most crops. The concentration of HLB and WTB required to kill half of earthworms\u2019 population (LC50; 95 % confidence limits) in the synthetic OECD soil was 338 and 580 t ha 121, respectively. Accumulation of polycyclic aromatic hydrocarbons (PAH) in earthworms exposed to the two biochar types at 100 t ha 121 was tested in two soils of different texture. In biochar-treated soils, the average earthworm survival rates were about 64 % in the sandy and 78 % clay-loam soils. PAH accumulation was larger in the sandy soil and largest in soils amended with HLB. PAH with less than four rings were preferentially scavenged from the soil by biochars, and this behaviour may mask that of the more dangerous components (i.e. four to five rings), which are preferentially accumulated. Earthworms can accumulate PAH as a consequence of exposure to biochar-treated soils and transfer them along the food chain. Soil type and biochar quality are both relevant in determining PAH transfer

The complexity of soil biological sustainability

Additions of organic amendments to soil not only compensate for decreased soil C, but also contribute to energy requirements for conserving biological activity levels. The soil microbial biomass displays some highly conserved, and possibly unique, characteristics that do not permit a classic interpretation of microbial metabolic parameter data. The resilience of soil microbial biomass and the role of soil organic matter in sustaining microbial biomass under practically zero C inputs were assessed in two long term incubation experiments using soils from the Broadbalk experiment at Rothamsted (UK). Soils with low organic C contents, showed the greatest decline in biomass C during the first 30 d of incubation. The ATP concentration of this rapidly declining microbial biomass did not change during the prolonged incubation period, confirming this peculiar character of the soil microbial biomass. Specific respiration rate did not depend upon substrate availability, being higher in soils that had received the lowest C inputs. Qualitative and quantitative changes observed in humic fractions suggest that humified soil organic matter is a much more dynamic soil fraction than is normally considered and provides a utilizable energy reserve for soil microorganisms. Carbon levels can be successfully restored in soils through practices such as incorporation of crop residues, re\u2010vegetation and application of manures, biosolids and composts. Some amendments, such as olive mill waste compost, promote incorporation of altered lignin structures, N\u2010containing compounds and carbohydrates into humic acids. The mineral\u2010bound fraction of humic C also increases, after their addition, and contributes to the accumulation of the most inert soil C pools

Effects of Long Term Hg Contamination on Soil Mercury Speciation and Soil Biological Activities.

The suspended matter discharged by the Isonzo river has carried over, for centuries, heavily contaminated mine spoils from the Idrija mercury mining site (Slovenija). A frequently flooded area at the confluence of the Isonzo and Torre rivers was chosen for a preliminary study on the effects of long term mercury pollution on soil biological activities, Hg speciation and plant bioavailability. Soil mercury contamination reached up to about 80 \ub5g g-1 near the banks of Isonzo river and decreased down to about 0.2 \ub5g g-1 near the Torre river, with the predominance of mercuric sulfide and elemental mercury. Soil microbial biomass was not adversely affected by Hg contamination as most soil biological activities, with the exception of arylsulphatase and acid phosphatase, which showed significant negative trends against total mercury and its fractions. Two plant genres (Arum spp. and Rubus spp.) were collected in four different places: Rubus spp. showed the largest uptake capacity of mercury (about 1 \ub5g g-1). Long term mercury contamination does not seem to constitute a stressing factor for soil biological activities but remains nevertheless a concern for its transfer through the food chain

Benthic nutrient cycling at the sediment-water interface in a lagoon fish farming system (northern Adriatic Sea, Italy)

Metabolism and carbon, oxygen, and nutrient fluxes (DIC, DOC, DO2, NO2 12, NO3 12, NH4+, PO4 3 12 and SiO4 4 12) were studied during three surveys at two sites (VN1 and VN3) located at a fish farm at theMarano and Grado Lagoon (northern Adriatic Sea), using an in situ benthic chamber. Field experimentswere conducted in July and October 2015 and March 2016 at a depth of approximately 2 m along the main channels of the fish farm.Water samples were collected by a scuba diver every 2 h in order to investigate daily fluxes of solutes across the sediment-water interface (SWI). Regarding the solid phase, Corg/Ntot and Corg/Porg molar ratios suggested an autochthonous marine origin of the organic matter and a minor preservation of P in the sediments, respectively; high values of sulphur (Stot) were also encountered (0.8\u20132%). The conditions at VN3 were mostly anoxic with high NH4 + levels (30\u20131027 \u3bcM) and the absence of NO3 12. Substantial daily patterns of all solutes occurred especially in autumn andwinter. On the contrary, fluxes at VN1were less pronounced. Usually, inverse correlations appeared between dissolved O2 and DIC trends, but in our systemthis was observed only at VN3 in autumn and accomplished by a parallel increase in NH4+, PO4 3 12 and SiO4 4 12 during intense nutrient regeneration. These results are significantly different than those reported for open lagoon environments,where nutrient regeneration at the SWI and in surface sediments is the primary source of nutrients available for assimilation processes, especially during the warmer period of the year when the natural nutrient input by fresh water inflows is limited. Due to the importance of this site for aquaculture, biodiversity and ecosystem services, useful suggestions have been provided from this study in order to improve the quality of this unique aquatic system

Monitoring of heavy metals, EOX and LAS in sewage sludge for agriculturale use: A case study

Subsequent to the increasing diffusion of wastewater treatment, particularly in high- and middle-income countries, the sewage sludge generated should be treated and valorised in an ecological and economic way, thus contributing to the circular economy. In this study, the monitoring of Heavy Metals (HM), Extractable Organic Halogens (EOX) and Linear Alkylbenzene Sulphonate (LAS) in sewage sludge from 10 different wastewater treatment plants located in Friuli Venezia Giulia (Italy) was reported, and their macronutrient content provided. The obtained results showed, for all tested samples, that HM content in sewage sludge was below the maximum permitted limits provided for by Italian and European regulations for agricultural reuse. Comparison with a similar monitoring campaign carried out in 2006 revealed how, while wastewater treatment plants efficiently resolved water pollution, they accumulated heavy metals and other persistent toxic compounds in sludge, thus restricting their potential reuse. Consequently, consistent and regular sludge monitoring should be undertaken to prevent soil and groundwater contamination. These outcomes could be of particular relevance for the future perspective of agricultural reuse of sewage sludge in waste management practices

Stand age, degree of encroachment and soil characteristics modulate changes of C and N cycles in dry grassland soils invaded by the N2-fixing shrub Amorpha fruticosa.

The N2-fixing shrub Amorpha fruticosa L. is rapidly spreading in the dry riparian natural grasslands of Europe, altering ecosystem functions and depleting plant diversity. Alteration of the N cycle represents the key factor involved in invasions by N2-fixing plants with cascading effects on plant species richness. We hypothesized that A. fruticosa encroachment strongly impacts not only the N but also the C cycle and that the magnitude of such alterations may be modulated by soil characteristics. To test these hypotheses, we selected four river floodplains in North East of Italy and compared natural uninvaded grasslands with half invaded and completely invaded sites, based on A. fruticosa stand characteristic and relevant leaf traits and on soil properties related to soil texture and to C and N cycles. Soil organic matter mineralisation, ammonification and nitrification rates were determined. Soil nitrification increased remarkably with plant invasion while ammonification was significantly higher only in half invaded sites. Soil organic matter mineralisation, microbial biomass C sustained per soil organic C unit and nitrification positively correlated with stand age, regardless to the stage of the encroachment. Mineralisation and nitrification increased with soil organic C and total N in uninvaded and completely invaded sites, but decreased in half invaded sites. At the half invasion stage, trends in nitrification and CO2 mineralisation were transitionally reverted and remediation may be facilitated by less pronounced changes in soil properties compared to completely invaded sites. Direct effects of plant invasion are modulated by the action of soil characteristics such as soil organic C and clay contents, with soils rich in organic C showing larger nitrification and mineralisation rates

An assay system to evaluate riboflavin/UV-A corneal phototherapy efficacy in a porcine corneal organ culture model

The purpose of this study is to investigate the response of a porcine corneal organ cultures to the riboflavin/UV-A phototherapy in the injury healing of induced lesions. A porcine corneal organ culture model has been established. Corneal alterations in the stroma were valuated setting an assay system, based on an automated image analysis method able to quantify the damaged (brightness values), within of the 24 regions of interest (ROIs) in which the corneal section has been divided and integrating the data analysis with a multi-aspect approach. Three group of corneas have been analyzed: (healthy, injured and injured-and-treated group). Our study revealed a significant effect of the riboflavin/UV-A phototherapy in the injury healing of porcine corneas after induced lesions. The injured corneas had significant differences of brightness values in comparison to treated (p< 0.00) and healthy (p<0.001) corneas whereas the treated and healthy corneas showed not significant difference (p = 0.995). Riboflavin/UV-A phototherapy shows a significant effect in the restoring the brightness values of damaged corneas to the values of healthy corneas, suggesting treatment restores the injury healing of corneas after lesions. Our assay system may be compared to clinical diagnostic method such as the OCT imaging for in vivo damaged ocular structures investigations

Changes in organic matter composition caused by {EDTA} washing of two soils contaminated with toxic metals

Two soils contaminated with potentially toxic metals (PTMs) contrasting in pH and mineralogy were remediated with CaEDTA, and changes in soil organic matter (SOM) composition were investigated. Previous studies showed no significant loss of SOM from CaEDTA-treated soils, but the results of our study reflected significant decreases (from 46 to 49%) in the free fraction of humic acids (HAs). Remediation affected the composition of the free HA fraction via disturbance of intermolecular bonds - an increase in phenolic and aromatic groups with a simultaneous decrease in carbohydrates - which was confirmed by FTIR spectroscopy in both soils. Because non-radical molecules such as carbohydrates were selectively removed, the concentration of free radicals in the free HA fraction increased in acidic soil. The bound fraction of HAs and fulvic acids (FAs) in SOM, which are important due to their stability and the permanent effects they have on the soil's physical properties, remained unchanged in both remediated soils. The effect of soil recultivation was observed only in the excitation emission matrix (EEM) fluorescence spectra of HAs. In terms of SOM, CaEDTA soil washing can be considered moderately conservative; however, the restoration of free humic fractions is likely to be a long-term process