In situ remediation of contaminated marinesediment: an overview

Sediment tends to accumulate inorganic and persistent hydrophobic organic contaminants representing one of the main sinks and sources of pollution. Generally, contaminated sediment poses medium- and long-term risks to humans and ecosystem health; dredging activities or natural resuspension phenomena (i.e., strongly adverse weather conditions) can remobilize pollution releasing it into the water column. Thus, ex situ traditional remediation activities (i.e., dredging) can be hazardous compared to in situ techniques that try to keep to a minimum sediment mobilization, unless dredging is compulsory to reach a desired bathymetric level. We reviewed in situ physico-chemical (i.e., active mixing and thin capping, solidification/stabilization, chemical oxidation, dechlorination, electrokinetic separation, and sediment flushing) and bio-assisted treatments, including hybrid solutions (i.e., nanocomposite reactive capping, bioreactive capping, microbial electrochemical technologies). We found that significant gaps still remain into the knowledge about the application of in situ contaminated sediment remediation techniques from the technical and the practical viewpoint. Only activated carbon-based technologies are well developed and currently applied with several available case studies. The environmental implication of in situ remediation technologies was only shortly investigated on a long-term basis after its application, so it is not clear how they can really perform

Experimental investigations and numerical modelling of in-situ reactive caps for PAH contaminated marine sediments

The present study compared numerical modelling and experimental investigations to evaluate the effectiveness of in-situ reactive capping for marine sediments contaminated by polycyclic aromatic hydrocarbons (PAHs). As a case study, sediment samples from Mar Piccolo (Italy) were analyzed and experiments were undertaken using batch columns. Two types of capping amendments were tested: AquaGate® + 5 % of powdered activated carbon (AG PAC) and Organoclay Reactive Core Mat (OC RCM). The column tests were carried out for 20 days, obtaining a short-term PAH distribution for three cases analysed, which compared the application of the two caps with no intervention. In parallel, in order to evaluate the intervention long term efficacy, an ad-hoc multilayered model predicting PAH concentrations into the sediments and the overlying water column was developed and validated with the experimental results. Both capping systems considerably reduced PAH concentrations in the overlying water, with the highest performance seen in AG PAC for benzo[a]pyrene (99 %) and anthracene (72 %); results also confirmed in the model predictions. In addition, the numerical simulations indicated a good efficiency of both caps over time, obtaining PAH values below the threshold limit in the long term. Although further experiments need to be developed accounting for multiple contamination competitiveness

The Improvement of Durability of Reinforced Concretes for Sustainable Structures: A Review on Different Approaches

The topic of sustainability of reinforced concrete structures is strictly related with their durability in aggressive environments. In particular, at equal environmental impact, the higher the durability of construction materials, the higher the sustainability. The present review deals with the possible strategies aimed at producing sustainable and durable reinforced concrete structures in different environments. It focuses on the design methodologies as well as the use of unconventional corrosion-resistant reinforcements, alternative binders to Portland cement, and innovative or traditional solutions for reinforced concrete protection and prevention against rebars corrosion such as corrosion inhibitors, coatings, self-healing techniques, and waterproofing aggregates. Analysis of the scientific literature highlights that there is no preferential way for the production of “green” concrete but that the sustainability of the building materials can only be achieved by implementing simulta-neous multiple strategies aimed at reducing environmental impact and improving both durability and performances

Methylobacterium Genome Sequences: A Reference Blueprint to Investigate Microbial Metabolism of C1 Compounds from Natural and Industrial Sources

Methylotrophy describes the ability of organisms to grow on reduced organic compounds without carbon-carbon bonds. The genomes of two pink-pigmented facultative methylotrophic bacteria of the Alpha-proteobacterial genus Methylobacterium, the reference species Methylobacterium extorquens strain AM1 and the dichloromethane-degrading strain DM4, were compared. Methodology/Principal Findings The 6.88 Mb genome of strain AM1 comprises a 5.51 Mb chromosome, a 1.26 Mb megaplasmid and three plasmids, while the 6.12 Mb genome of strain DM4 features a 5.94 Mb chromosome and two plasmids. The chromosomes are highly syntenic and share a large majority of genes, while plasmids are mostly strain-specific, with the exception of a 130 kb region of the strain AM1 megaplasmid which is syntenic to a chromosomal region of strain DM4. Both genomes contain large sets of insertion elements, many of them strain-specific, suggesting an important potential for genomic plasticity. Most of the genomic determinants associated with methylotrophy are nearly identical, with two exceptions that illustrate the metabolic and genomic versatility of Methylobacterium. A 126 kb dichloromethane utilization (dcm) gene cluster is essential for the ability of strain DM4 to use DCM as the sole carbon and energy source for growth and is unique to strain DM4. The methylamine utilization (mau) gene cluster is only found in strain AM1, indicating that strain DM4 employs an alternative system for growth with methylamine. The dcm and mau clusters represent two of the chromosomal genomic islands (AM1: 28; DM4: 17) that were defined. The mau cluster is flanked by mobile elements, but the dcm cluster disrupts a gene annotated as chelatase and for which we propose the name “island integration determinant” (iid).Conclusion/Significance These two genome sequences provide a platform for intra- and interspecies genomic comparisons in the genus Methylobacterium, and for investigations of the adaptive mechanisms which allow bacterial lineages to acquire methylotrophic lifestyles.Organismic and Evolutionary Biolog

Wage differentials associated with race between 2002 and 2014 in Brazil: Evidence from a quantile decomposition

Throughout the 2000s Brazil went through a great phase of economic development. The present study seeks to investigate whether this movement was accompanied by a reduction in inequality in the labor market, measured here by the wage gap between whites and non-whites. To do so, three cohorts of time (2002-2004, 2007-2009 and 2012-2014) were analyzed from the microdata of the National Household Sampling Survey (Pesquisa Nacional de Amostragem Domiciliar - PNAD). The applied method is the counterfactual Oaxaca-Blinder along with the Recentered Influence Function Regression (RIF-Regression) so that the main determinants of wages inequalities can be detailed throughout the salary distribution. Our results showed that wage gap (totals, due to observed factors and discrimination) are higher in the higher quantiles of the distribution, that is, in professions or activities with higher wages. The results also point to a salary approximation between the groups during the analyzed period, which was mainly due to observable characteristics, specially education levels. However, discrimination decreased only between the first and second triennium and in low magnitude. Apart from that, the main determinants of racial wage gap are returns to education, experience and professions considered unregulated (self-employment and informal workers)

Year class strength and catchability of mountain lake brook trout

Increased gillnet catch per effort (cpe) of juvenile salmonids occurred following intense exploitation of the adult population, for several studies conducted in mountain and arctic small lakes. Higher cpe may reflect increased catchability or greater numbers, so behavioral or numerical responses cannot be inferred from changes in cpe alone. I used age structured estimation methods, and gillnet depletion data from 1986 to 1992 for seven Sierra Nevada small lake brook trout populations, to reconstruct year class strength and prerecruit (age 1) gillnet catchability prior to and during the experimental removals. I made Walters-Collie (1988) estimates of year class strength for the seven study lakes across the years of the removals. The within-year depletions and available models consistently underpredicted the number of fish remaining in the lake, so estimates did not use the within-year structure of the data. Ageing error correction provided little change in the estimated strength of cohorts produced during the mid- to late 1980's. Estimates showed an inverse relationship between year class strength and adult population size, for cohorts from 1984 to 1990. Prerecruit q[carat] also appeared inversely related to adult population density for most lake populations. This may have been either a direct effect of adult density, or indirectly mediated through the effect of adult density on prerecruit length at age. Year and cohort-specific adult q[carat]'s showed little evidence for density dependence in adult q[carat]. The vulnerable proportion of the adult population appeared insensitive to population density. I developed a modification of the WC fitting to adjust for between-lake variation in encounter probability which estimated a relative activity parameter, k[carat] . Relative to q[carat], variation in k[carat] was reduced and showed little apparent between-lake density dependence.Science, Faculty ofZoology, Department ofGraduat

Clean up of heavy hydrocarbons contaminated groundwater by oil belt skimmer technology

The oil belt skimmer consists of a continuously moving belt that runs on a pulley system driven by an electric motor. Typically, belt skimmers remove very little water with the contaminant. Taking into account this consideration, the objective of our work was to verify the applicability of oil belt skimmer technology for the remediation of a groundwater polluted by heavy hydrocarbons. For this purpose, two fields of study were addressed: (i) hydrodynamic study of supernatant layer and (ii) study of the oil belt skimmer plant. The obtained results showed the feasibility of the oil belt skimmer technology in recovering oil from groundwater with a recovery efficiency of 98%. Furthermore, results showed how the recovery of oil depends primarily on the amount of emulsion (water + oil) existing initially. Considering full-scale experimentations, they showed that, after 1 year of trial, the recovery percentage were 75%, 84% and 87% for the skimmers installed in correspondence of carwash, fuel tank and repair shop (pollutions sources), respectively. Moreover, the recovery capacity of the skimmer depends on the rainfall pattern and the max recovery capacities have always occurred after intense and short rain. Still, the recovery capacity depends also on the fluctuation of groundwater in turn influenced by the sea. Although the percentage of recovery of the pump and treat was greater than in the case of the oil belt skimmer, the investigated technology allow to reduce the amount of waste to be disposed respect to the pump and treat technology. Therefore, the oil belt skimmer represents an excellent alternative for the remediation of contaminated groundwater

Is it a NiMBY or WhyMBY case of locally unwanted land use?

NiMBY is the acronym of Not in My Back Yard, a form of protest by a group of people who see the security of their area of residence threatened by the siting of unwanted facilities such as municipal solid waste (MSW) treatment or disposal plants. In the paper the new concept of ‘WhyMBY’ is introduced as a pro-justice-based approach, where citizens want to be convinced that their backyard is the best location compared with many, or even all, other possible locations. Two proposed localizations for the treatment of putrescibles from MSW, in the Campania region of Southern Italy, are examined in order to understand if they are cases of NiMBY or WhyMBY: one in the province of Avellino, in the municipality of Chianche, another in the province of Salerno, in the municipality of Fisciano. The analysis performed suggests that the first case study seems a NiMBY case, while the second one seems an intermediate NiMBY/WhyMBY case. The adoption of a different localization process from the optimal one, also due to emergency reasons, generated inevitable opposition from citizens. For the future, it will be necessary to adopt siting procedures capable of implementing al the required phases: macro-siting, micro-siting and evaluation of potentially suitable alternatives. Finally, in these procedures, information and awareness campaigns must play a fundamental role