Molecularly imprinted polymers for the detection of benomyl residues in water and soil samples

Benomyl is a benzimidazol fungicide used against various crop pathogens. Although banned in many countries, it is still widely used worldwide and is listed in different monitoring programs among the substances to be monitored to assess human exposure to pesticide residues. The assessment of benomyl is mainly based on the analysis of the residues of its most important metabolite, carbendazim. Existing methods often lack of selectivity and display a limited performance because of the presence of co-extracted compounds. Molecularly imprinted polymers (MIPs) offer an alternative methodology, adsorbing preferentially those target molecules for which the polymers are specifically prepared. In this study, we optimized the synthesis of a polymer imprinted with benomyl. Tests of specificity recognition showed a good performance for carbendazim compared with other similar pesticides. The mean recovery of benomyl (measured as carbendazim) from water samples was estimated to be 90% for MIPs while with real soil samples collected in Morocco the recovery efficiency was 62%. Preliminary tests also suggest that this MIP can implement traditional SPE techniques for assessing benomyl residual concentrations in environmental samples.     

Performance of some biotic indices in the real variable world: A case study at different spatial scales in North-Western Mediterranean Sea

The aim of this study was to analyse the variability of four different benthic biotic indices (AMBI, BENTIX, H′, M-AMBI) in two marine coastal areas of the North-Western Mediterranean Sea. In each coastal area, 36 replicates were randomly selected according to a hierarchical sampling design, which allowed estimating the variance components of the indices associated with four different spatial scales (ranging from metres to kilometres). All the analyses were performed at two different sampling periods in order to evaluate if the observed trends were consistent over the time. The variance components of the four indices revealed complex trends and different patterns in the two sampling periods. These results highlighted that independently from the employed index, a rigorous and appropriate sampling design taking into account different scales should always be used in order to avoid erroneous classifications and to develop effective monitoring programs.     

Binary mixtures of azinphos-methyl oxon and chlorpyrifos oxon produce in vitro synergistic cholinesterase inhibition in Planorbarius corneus

In this study, the cholinesterase (ChE) and carboxylesterase (CES) activities present in whole organism homogenates from Planorbarius corneus and their in vitro sensitivity to organophosphorous (OP) pesticides were studied. Firstly, a characterization of ChE and CES activities using different substrates and selective inhibitors was performed. Secondly, the effects of azinphos-methyl oxon (AZM-oxon) and chlorpyrifos oxon (CPF-oxon), the active oxygen analogs of the OP insecticides AZM and CPF, on ChE and CES activities were evaluated. Finally, it was analyzed whether binary mixtures of the pesticide oxons cause additive, antagonistic or synergistic ChE inhibition in P. corneus homogenates. The results showed that the extracts of P. corneus preferentially hydrolyzed acetylthiocholine (AcSCh) over propionylthiocholine (PrSCh) and butyrylthiocholine (BuSCh). Besides, AcSCh hydrolyzing activity was inhibited by low concentrations of BW284c51, a selective inhibitor of AChE activity, and also by high concentrations of substrate. These facts suggest the presence of a typical AChE activity in this species. However, the different dose-response curves observed with BW284c51 when using PrSCh or BuSCh instead of AcSCh suggest the presence of at least another ChE activity. This would probably correspond to an atypical BuChE. Regarding CES activity, the highest specific activity was obtained when using 2-naphthyl acetate (2-NA), followed by 1-naphthyl acetate (1-NA); p-nitrophenyl acetate (p-NPA), and p-nitrophenyl butyrate (p-NPB). The comparison of the IC(50) values revealed that, regardless of the substrate used, CES activity was approximately one order of magnitude more sensitive to AZM-oxon than ChE activity. Although ChE activity was very sensitive to CPF-oxon, CES activity measured with 1-NA, 2-NA, and p-NPA was poorly inhibited by this pesticide. In contrast, CES activity measured with p-NPB was equally sensitive to CPF-oxon than ChE activity. Several specific binary combinations of AZM-oxon and CPF-oxon caused a synergistic effect on the ChE inhibition in P. corneus homogenates. The degree of synergism tended to increase as the ratio of AZM-oxon to CPF-oxon decreased. These results suggest that synergism is likely to occur in P. corneus snails exposed in vivo to binary mixtures of the OPs AZM and CPF.     

Factors affecting the growth rates of ammonium and nitrite oxidizing bacteria

The maximum specific growth rates of both ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were investigated under varying aerobic solids retention time (SRT_a) and in the presence/absence of anoxic (alternating) conditions. Two bench SBRs, reactor R1 and R2, were run in parallel for 150 d. Reactor R1 was operated in aerobic conditions while R2 operated in alternating anoxic/aerobic conditions. The feed (synthetic wastewater), temperature, hydraulic retention time and mixing were identical in both reactors. The SRT_a in both reactors was, sequentially, set at four values: 5, 4, 3 and 2 d.Kinetic tests with the biomasses from both reactors were carried out to estimate the maximum specific growth rates (μ_max) at each tested SRT_a and decay rates, in both aerobic and anoxic conditions. The kinetic parameters of nitrifier were estimated through the calibration of a two step nitrification-denitrification activated sludge model.The results point to a slightly higher μ_max,AOB and μ_max,NOB in alternating conditions, while both μ_max,AOB and μ_max,NOB were shown not to vary in the tested range of SRT_a (from 2 to 5 d) at 20 °C. They were relatively high when compared to literature data: 1.05 d⁻¹ < μ_max,AOB < 1.4 d⁻¹ and 0.91 d⁻¹ < μ_max,NOB < 1.31 d⁻¹. The decay coefficients of both AOB and NOB were much higher in aerobic (from 0.22 d⁻¹ to 0.28 d⁻¹) than in anoxic (0.04 d⁻¹ to 0.16 d⁻¹) conditions both in R1 and R2, which explained the higher nitrification rates observed in the alternating reactor.     

Comparative management of offshore posidonia residues: composting vs. energy recovery

Residues of the marine plant posidonia (Posidonia oceanica, PO) beached in tourist zones represent a great environmental, economical, social and hygienic problem in the Mediterranean Basin, in general, and in the Apulia Region in particular, because of the great disturb to the bathers and population, and the high costs that the administrations have to bear for their removal and disposal.In the present paper, Authors determined the heating values of leaves and fibres of PO, the main offshore residues found on beaches, and, meantime, composted those residues with mowing and olive pruning wood. The final composts were characterized for pH, electrical conductivity, elemental composition, dynamic respiration index, phytotoxicity, fluorescence and infrared spectroscopic fingerprints.The aim of the paper was to investigate the composting and energy recovery of PO leaves and fibres in order to suggest alternative solutions to the landfill when offshore residues have to be removed from recreational beaches.The fibrous portion of PO residues showed heating values close to those of other biofuels, thus suggesting a possible utilization as source of energy.At the same time, compost obtained from both PO wastes showed high quality features on condition that the electrical conductivity and Na content are lowered by a correct management of wetting during the composting.     

Implication of soil C sequestration on sustainable agriculture and environment

Soil organic matter (SOM) is the largest C stock of the continental biosphere with 1550Pg. The size of C reservoir in the soil and environmental concerns on climate change have recently attracted the attention of scientist and politicians on C sequestration as an effective strategy to tackle greenhouse gas (GHG) emissions. It has been estimated that the potential for C storage in world cropland is relevant (about 0.6-1.2PgCy(-1)). However, there are several constraints of C sequestration that raise concern about its effectiveness as a strategy to offset climate change. C sequestration is finite in quantity and time, reversible, and can be further decreased by socio-economic restrictions. Given these limitations, C sequestration can play only a minor role in the reduction of emissions (2-5% of total GHG emission under the highest emission scenarios). Yet, C sequestration is still attractive for two main reasons: it is likely to be particularly effective in reducing atmospheric CO2 levels in the first 20-30yr of its implementation and presents ancillary benefits for environment and sustainability that make it a real win-win strategy. These beneficial implications are discussed in this paper with emphasis on the need of C sequestration not only to offset climatic changes, but also for the equilibria of the environment and for the sustainability of agriculture and of entire human society.     

Satellite-based indices in the analysis of land cover for municipalities in the province of Siena, Italy

Territorial indicators based on the satellite measured reflected or emitted energy can provide valuable information on the spatial evolution of a territory. Information regarding land use, biomass coverage and radiant temperature were obtained from remotely obtained measurements for each municipality in the Province of Siena. Remotely sensed data were combined into different indices to compare characteristics of land cover between territories and create an information base for continued study. A classification was performed on a municipal level and land use classes were grouped together and a general index of use pressure was created. A vegetation index was used to compare biomass densities. A radiant temperature index was calculated using measure thermal infrared emissions. The results of these analyses allowed researchers to examine the intra and inter-municipal spatial heterogeneity within the Province. A comparison between the results of each index was made and the problems related to the use of such indices were examined.     

On the effect of pH in aromatic photonitration upon nitrate photolysis

This paper studies the pH effect on the photonitration of catechol, 1-naphthol, naphthalene, and benzene. The pH trend is influenced by the generation of HNO(2) and peroxynitrous acid (HOONO) upon nitrate photolysis. HNO(2) can be involved in a direct and an indirect nitration process. Direct nitration follows the pH distribution of HNO(2) (flexus around 3). Indirect nitration, possibly involving nitrosation+oxidation, would be highest around pH3. HOONO can be involved in electrophilic nitration, where the initial formation rate of the nitroderivatives is proportional to [H(+)], or take part in nitration directly, in which case a less important pH effect in photonitration is observed. The relative importance of the various nitration pathways for each substrate determines the resulting pH effect in photonitration upon nitrate photolysis.     

Analysis of volatile organic compounds (VOCs) in sediments using in situ SPME sampling

A new method of determining the composition of sediment/soil gases and their volatile organic compound (VOC) content is described. VOCs were collected in situ from intertidal sediments in the Menai Strait and surrounding areas. The sampling was performed using a portable sampler comprising a funnel coupled to a SPME fibre. Gases were extracted from the sediments using a small vacuum pump pulling 100 mL min(-1) at atmospheric pressure. Sixty one different compounds were detected in the samples, and their fluxes and concentrations were determined. The compounds were classified into groups: halogenated, sulfur containing compounds, aldehydes, BTEXs (benzene, toluene, ethyl benzene and xylene) and aliphatic hydrocarbons. Results of principal component analysis (PCA) showed that the chemical composition of extracted gas was influenced primarily by sediment type. Muddy anoxic sediments were dominated by halogenated and sulfur containing compounds and sandy sediments had more aldehydes and BTEXs.