The Poverty-Environment Trap in a Modified Romer Model with Dirtiness

The model presented in this paper describes an economy with endogenous technical change and polluting production techniques. The main question we want to address is whether the adoption of “dirty” production processes might lead to a sustainable unique steady state, or guarantee the emergence of multiple equilibria. The application of the original Bogdanov–Takens theorem allows us to characterize the regions of the parametric space where the model exhibits either a global indeterminate equilibrium or a poverty-environment trap.     

Carbon deposition in soil rhizosphere following amendments with compost and its soluble fractions, as evaluated by combined soil-plant rhizobox and reporter gene systems

We determined the organic carbon released by roots of maize plants (Zea mays L.) when grown in soils amended with compost and its soluble fractions. In rhizobox systems, soil and roots are separated from the soil of a lower compartment by a nylon membrane. Treatments are applied to the upper compartment, while in the lower compartment luminescent biosensors measure the bioavailable organic carbon released by roots (rhizodeposition). The rhizobox-plants systems were amended with a compost (COM), its water extract (TEA), the hydrophobic (HoDOM) and hydrophilic (HiDOM) fractions of the dissolved organic matter (DOM) extracted from the compost. After root development, the lower untreated compartments were sampled and sliced into thin layers. The bioavailable organic carbon in each layer was assessed with the lux-marked biosensor Pseudomonas fluorescens 10586 pUCD607, and compared with total organic carbon (TOC) analyses. The TOC values ranged between 8.4 and 9.6 g kg(-1) and did not show any significant differences between bulk and rhizosphere soil samples in any treatment. Conversely, the biosensor detected significant differences in available C compounds for rhizosphere soils amended with various organic materials. Concentrations of available organic compounds in the first 2 mm of soil rhizosphere were 1.69 (control), 1.09 (COM), 2.87 (HiDOM), 4.73 (HoDOM) and 2.14 (TEA)micromol Cg(-1) soil g(-1) roots. The applied rhizobox-biosensor integrated method was successful in detecting and quantifying effects of organic amendments on organic carbon released by maize plant roots. This approach may become important in assessing the carbon cycle in agricultural soils and soil-atmosphere compartments.     

Analysis of perfluorooctanoate (PFOA) and other perfluorinated compounds (PFCs) in the River Po watershed in N-Italy

C7-C11 perfluorinated carboxylates (PFACs) and perfluorooctansulfonate (PFOS) were analysed in selected stretches of the River Po and its major tributaries. Analyses were performed by solid-phase extraction (SPE) with Oasis HLB cartridges and methanol elution followed by LC-MS-MS detection using 13C-labelled internal standards. High concentration levels ( approximately 1.3 microg l(-1)) of perfluorooctanoate (PFOA) were detected in the Tánaro River close to the city Alessandria. After this tributary, levels between 60 and 337 ng l(-1) were measured in the Po River on several occasions. The PFOA concentration close to the river mouth in Ferrara was between 60 and 174 ng l(-1). Using the river discharge flow data in m3 s(-1) at this point (average approximately 920 m3 s(-1) for the year 2006), a mass load of approximately 0.3 kg PFOA per hour or approximately 2.6 tons per year discharged in the Adriatic Sea has been calculated. PFOS concentration levels in the Po River at Ferrara were approximately 10 ng l(-1).     

Vegetable and synthetic tannins induce hormesis/toxicity in sea urchin early development and in algal growth

Mimosa tannin and phenol-based synthetic tannin (syntan) were tested for toxicity to sea urchin (Paracentrotus lividus and Sphaerechinus granularis) early development and to marine algal growth (Dunaliella tertiolecta). Sea urchin embryogenesis was affected by vegetable tannin and syntan water extracts (VTWE and STWE) at levels >or=1mg/L. Developmental defects were significantly decreased at VTWE and STWE levels of 0.1 and 0.3mg/L when control cultures displayed suboptimal quality, i.e. <70% "viable" (normal or retarded) larvae. Fertilization success of sea urchin sperm was increased up to 0.3 mg/L STWE or VTWE, then was inhibited by increasing tannin levels (1-30 mg/L). Offspring abnormalities, following sperm exposure to VTWE or STWE, showed the same shift from hormesis to toxicity. Cell growth bioassays in D. tertiolecta exposed to VTWE or STWE (0.1-30 mg/L) showed non-linear concentration-related toxicity. Novel criteria are suggested in defining control quality that should reveal hormetic effects.     

Winter survival of microbial contaminants in soil:An in situ verification

The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10 cm below ground, while,after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5 cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter.     

Pesticide dissipation curves in peach, pear and tomato crops in Uruguay

Dissipation curves of azoxystrobin and of the neonicotinoids acetamiprid and thiacloprid in peach; azinphos-methyl and carbaryl in pear and azoxystrobin, chlorfenapyr and chlorpyrifos in high-tunnel tomato crops were studied in the Southern region of Uruguay. An analytical methodology based on solid phase extraction (SPE) and detection by High Performance Liquid Chromatography with Diode Array Detector (HPLC/DAD) was used for acetamiprid and thiacloprid. Coupled SPE and detection by Gas Chromatography with Mass Selective Detector (GC/MSD) was used for the detection of azinphos-methyl, azoxystrobin, carbaryl, chlorfenapyr and chlorpyrifos residues. Curves were modeled mathematically with Solver program of Microsoft Excel. The best fit for acetamiprid and thiacloprid in peach was achieved with the exponential model (r(2)=0.961 and 0.944, respectively). In the case of peach fruits there is not a Maximum Residue Limit (MRL) for acetamiprid in the Codex Alimentarius, while 0.5 mg/kg is the value rated for thiacloprid. The MRLs accepted by the European Union (EU) are 0.1 mg/kg for acetamiprid and 0.3 mg/kg for thiacloprid. According to the curves determined in these experiments, thiacloprid residues 10 to 12 days after application (daa) were below the MRLs established by both sources. In the case of acetamiprid, 25 daa would be required, according to the exponential mathematical model, to get residues levels below the MRL values established by the EU. For azinphos methyl in pear, the residues detected were mathematically fitted to an exponential model (r(2)=0.999). According to it, residue levels under the MRL established by the EU (0.05 mg/kg) are gotten in our conditions in 20 daa. In plastic tunnel tomato chlorfenapyr residues were not detected from 16 daa, having the dissipation curve an exponential trend. In the same condition, there was not a decay of the azoxystrobin concentration during a 24-day trial, being it around 0.40 ± 0.05 mg/kg.     

Comparative abiotic or biotic degradation of carboxin by two Entisols with different surface properties or Pseudomonas aeruginosa strain: A toxicity study using the crustacean Thamnocephalus platyurus

The microcrustacean Thamnocephalus platyurus was used to detect the toxicity reduction of carboxin in abiotic degradation compared to biotic degradation. The abiotic degradation was obtained using two sterilized Entisols with different surface properties while the biotic degradation by Pseudomonas aeruginosa was obtained using the fungicide as the only C source. The results showed that the highest toxicity reduction rates for the abiotic degradation were achieved in 20 days with 49.2% for the coarser soil, 60.7% for the soil with a finer texture, whereas for the biotic degradation, 60.6%. Analysis (¹H NMR) showed that the soils transformed carboxin to produce sulfoxide and enol in different concentrations depending on the soil properties, while P. aeruginosa metabolized the fungicide to produce inorganic compounds such as ammonium and nitrite, minor degradation pathways were oxidized to sulfoxide and hydrolytic ring-opening to 2-[(2-hydroxyethyl)thio]acetoacetanilide enol. These results indicated that the degradation of carboxin occurred via abiotic catalytic processes as well as via biotic transformation leading to less toxic derivatives and such phenomena are caused by exchange/surface features of soils, rather than by the mere content of clay or organic matter fractions.     

Evaluation of a temporal trend heavy metals contamination in Posidonia oceanica (L.) Delile, (1813) along the western coastline of Sicily (Italy)

The use of biological species in the monitoring of marine environmental quality allows the evaluation of biologically available levels of contaminants in the ecosystem and the effects of contaminants on living organisms. The seagrass Posidonia oceanica is a useful bioindicator because through the lepidochronology technique it is possible to obtain a historical contamination trend of a given area. This study aims to assess the temporal trend contamination by heavy metal investigations on dead sheaths of 100 samples of P. oceanica collected in the Protected Marine Area of "Plemmirio" (Sicily) and in the Siracusa bay. Important results were obtained because data show a significant negative temporal trend for the metals analysed especially for As, Co, Cr, Hg, Pb, Se, U and V that in the past had higher concentrations, with a stronger contamination in the Plemmirio area, the site much more exposed to the pollution of the nearby petrochemical complex. This study confirms the relevance of the use of P. oceanica as a biological indicator of metal contamination in coastal ecosystems. Thus the usefulness of P. oceanica as a tracer of spatial metal contamination and as a good tool for water quality evaluation is reinforced.