Application of synthetic and natural surfactants for mobilizing pahs in marine sediments for remediation purposes

The presence of Polycyclic Aromatic Hydrocarbons (PAHs) in marine sediments is one of the major concern for human health and marine ecosystem because of their toxicity, mutagenicity and carcinogenicity [1]. The increase of industrial and urbanization processes contributes to rise PAHs level in the coastal regions. They readily associate with inorganic and organic suspended particles and may accumulate in sediments at high concentrations, due to their low solubility and hydrophobic nature [2]. In recent years, the use of surfactants, as soil-washing agents, is becoming particularly attractive for their low toxicity and favourable biodegradability in the environment relative to organic-solvent based systems [3]. It has been reported that the success of soil-washing with surfactants can be attributed to the capacity of these compounds to appreciably enhance the aqueous solubility of hydrophobic organic compounds [4] and then the efficiency of contaminants mobilization. The aim of this research is the evaluation of the ability to solubilize and mobilize PAHs of different non-ionic and biodegradable surfactants, synthetic or biosurfactants, in order to remediate heavily contaminated sediments. Investigated Surfactants’ families are Alkylpolyglycosides (APGs), Sophorolipids (SLs) and Rhamnolipids (RLs). Sediments from Bagnoli (Italy), Site of National Interest, since interested in the past by a heavy industrial contamination, had been collected during ABBaCo Project [5]. More than 100 samples were characterized, and among these, the 28 most contaminated samples were combined and homogenized in a 1,350 Kg stock, which is taken as a reference sample. Firstly, the characterization of PAHs’ starting contamination (total and for each compound) of these sediments has been conducted, taking three aliquots from the stock. Then, different batch configuration tests (washes at 5xCMC, kinetic, washing and concentration) have been carried out to study the ability of investigated surfactants to mobilize sorbed contaminants. From the obtained results, the most performant surfactants are currently under investigation in soil flushing test in column. The characterization of the sediments revealed a heavy PAHs contamination. All the available surfactants contribute to enhance the solubility of contaminants compared to water, with APG2 and SL being the best synthetic and natural surfactants, respectively. From the different tests, important data are obtained: the different chemical properties (e.g., solubility) of “light” (< 4 rings) and “heavy” PAHs (≥ 4 rings), the number of washes which increases the amount of PAHs removed and the relevance of surfactants’ concentration in order to enhance the solubility of PAHs in water. As in the washes at 5xCMC test at the maximum concentration experimented, APG2 and SL resulted the most performing surfactants, new experiments in column are conducted: firstly just water, then surfactant APG2 and SL (1% m/m) in solution flow through the column filled of contaminated sediment. The results, after two weeks of elution, show that a low amount of total PAHs are solubilized in water from the sediment, while a solution with APG2 or SL reach a better total removal than water. References [1] F. Botsou, "Polycyclic aromatic hydrocarbons (PAHs) in marine sediments of the Hellenic coastal zone, eastern Mediterranean: levels, sources and toxicological significance," J. Soils Sediments, vol. 12, pp. 265–277, 2012. [2] A. Nikolaou, "Levels and toxicity of polycyclic aromatic hydrocarbons in marine sediments," TrAC Trends Anal. Chem., vol. 28, pp. 653–664, 2009. ICEPR 135-2 [3] Y. Tao, "Optimizing a washing procedure to mobilize polycyclic aromatic hydrocarbons (PAHs) from a field contaminated soil," Ind. Eng. Chem. Res., vol. 46, pp. 4626–4632, 2007. [4] S. Laha, "Surfactant–soil interactions during surfactant-amended remediation of contaminated soils by hydrophobic organic compounds: A review," J. Environ. Manage., vol. 90, pp. 95–100, 2009. [5] MERCE. (2016). ABBaCo Project. [online]. Available: http://www.merces-project.eu/?q=content/abbaco-project-

Determination of selected polychlorinated dibenzo-p-dioxins/furans in marine sediments by the application of gas-chromatography-triple quadrupole mass spectrometry

Selected polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were detected by gas-chromatography coupled to triple quadrupole mass spectrometry (GC-QqQ-MS/MS) in marine sediments collected in central Italy. Total PCDD/Fs concentrations ranged from 11.58 to 193.29 pg/g d.w., with PCDFs as the major contributors in most cases. The congener profiles were characterized by high OCDD (70.7 %-91.4 %). The PCDD/Fs values are within or close to the Environmental Canada sediment reference values (0.85 pg TEQ/g d.w.). GC-QqQ-MS/MS can be a suitable alternative to standard methods for PCDD/Fs determination in environmental samples. The measured PCDD/Fs amounts could be considered as a basis for future monitoring programs. © 2013 Springer Science+Business Media New York

Heavy Metal Pollution and Potential Ecological Risks in Rivers: A Case Study from Southern Italy

We monitored heavy metal (As, Cd, Hg, and Pb) concentrations in surface water, sediments, and oligochaetes in four major rivers in Calabria (southern Italy) over the course of 1 year. As, Cd, and Pb showed accumulation factors of 103-105 for water to sediment and 1-10 for sediment to oligochaetes. Hg showed a water to sediment accumulation factor of 10-100. Finally, Hg concentrations exceeded the Italian quality standard for freshwater in all of the rivers, and As concentrations in sediments exceeded the respective Canadian standard. However, the application of an ecological risk assessment method indicated low risks for all monitored rivers. © 2013 Springer Science+Business Media New York

On reducing VOCs concentration from groundwater for irrigation purposes: A detailed monitoring program to test the stripping efficiency of a sprinkler system.

Groundwater contamination is one of the major environmental problems throughout the world. This is partly because groundwater can transport a substance quite easily and even extensively toward a receptor. Agriculture is a weak link in this context since, for example, fresh produce irrigated with low-quality water is a major factor contributing to some human diseases. Apart from pathogenic microorganisms, a gross source of groundwater contamination is by volatile organic compounds (VOCs). In this paper, we present and discuss a monitoring activity of transport processes in the soil-vegetation-atmosphere continuum to evaluate the effectiveness of a sprinkler irrigation system specifically-designed to reduce the COVs’ concentrations in a contaminated site. For phytoremediation purposes, this test site is planted with poplar trees

A chemical remediation technique for a nearly-total removal of arsenic and mercury from contaminated marine sediments

After decades of industrial exploitation of the coast and consequent contamination of the sites and marine sediments, it became essential to recover the marine ecosystem by remediation methods to remove toxic contaminants. In this work, a remediation method was developed to clean marine sediments contaminated by arsenic (As) and mercury (Hg). The method can be applied to mobile platforms and is based on an environmentally friendly approach designed to minimise further contamination. The method was tested on two artificially contaminated sediments and two real samples collected from two highly contaminated sites in southern Italy, Augusta Bay and Bagnoli Gulf, characterised by high Hg and As concentrations, respectively. The method consists of four steps: washing with sodium hydroxide (NaOH) to remove metals associated with humic acid; Fenton-reaction using α-CycloDextrin (aCD) to stabilise Fe(II) at natural pH and oxidise As (III) and Hg (0 or I); complexation reaction with aCD; and complexation with sodium sulfide (Na2S) to remove Hg as soluble Hg-polysulfides. Compared to other remediation experiences in literature, this technique provides the best removal efficiency for As and Hg (ranging between 26 -71 % and 57–95 %, respectively). Considering the residual concentrations of As and Hg and the contamination threshold fixed by European Regulation for re-use, the treated sediment can be used in several civil and industrial contexts. The presented method operates in line with the principles of the circular economy to preserve natural resources, prevent secondary pollution, and promote the effective re-use of clean environmental matrices (soils, sediments and aqueous solutions), thus minimising landfill waste

Encapsulated in sediments: eDNA deciphers the ecosystem history of one of the most polluted European marine sites

The Anthropocene is characterized by dramatic ecosystem changes driven by human activities. The impact of these activities can be assessed by different geochemical and paleontological proxies. However, each of these proxies provides only a fragmentary insight into the effects of anthropogenic impacts. It is highly challenging to reconstruct, with a holistic view, the state of the ecosystems from the preindustrial period to the present day, covering all biological components, from prokaryotes to multicellular eukaryotes. Here, we used sedimentary ancient DNA (sedaDNA) archives encompassing all trophic levels of biodiversity to reconstruct the two century-natural history in Bagnoli-Coroglio (Gulf of Pozzuoli, Tyrrhenian Sea), one of the most polluted marine-coastal sites in Europe. The site was characterized by seagrass meadows and high eukaryotic diversity until the beginning of the 20th century. Then, the ecosystem completely changed, with seagrasses and associated fauna as well as diverse groups of planktonic and benthic protists being replaced by low diversity biota dominated by dinophyceans and infaunal metazoan species. The sedaDNA analysis revealed a five-phase evolution of the area, where changes appear as the result of a multi-level cascade effect of impacts associated with industrial activities, urbanization, water circulation and land-use changes. The sedaDNA allowed to infer reference conditions that must be considered when restoration actions are to be implemented

Results from the International Halocarbons in Air Comparison Experiment : (IHALACE) [Discussion paper]

The International Halocarbons in Air Comparison Experiment (IHALACE) was conducted to document relationships between calibration scales among various laboratories that measure atmospheric greenhouse and ozone depleting gases. Six stainless steel cylinders containing natural and modified natural air samples were circulated among 19 laboratories. Results from this experiment reveal relatively good agreement among commonly used calibration scales for a number of trace gases present in the unpolluted atmosphere at pmol mol−1 (parts per trillion) levels, such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Some scale relationships were found to be consistent with those derived from bi-lateral experiments or from analysis of atmospheric data, while others revealed discrepancies. The transfer of calibration scales among laboratories was found to be problematic in many cases, meaning that measurements tied to a common scale may not, in fact, be compatible. These results reveal substantial improvements in calibration over previous comparisons. However there is room for improvement in communication and coordination of calibration activities with respect to the measurement of halogenated and related trace gases