The role of iron nanoparticles on anaerobic digestion: mechanisms,limitations, and perspectives

Environmental Science and Pollution Research - Anaerobic digestion (AD) is the most widely used technology for organic matter treatment. However, multiple types of research have reported on...     

Spine anatomy reveals the diversity of catfish through time: a case study of Synodontis (Siluriformes)

Synodontis (Mochokidae, Siluriformes) is a freshwater catfish endemic to Africa. The 118 extant species are present in almost all hydrographic basins. Some species are restricted to a single stream, whereas others have a vast distribution. Synodontis is known in the fossil record since the Miocene, and its history depends on the connections among African basins through time. The identification of species in the fossil record is essential to reconstruct this historical pattern. Catfish pectoral and dorsal spines are robust, they preserve well and they form most of the fossil remains for the genus Synodontis. Unfortunately, the criteria for the identification of extant Synodontis species are not applicable to fossil specimens. Here, we define 11 original morphological characters that permit to discriminate four extant species from the Chad-Chari hydrographic system. Six of these characters are defined on pectoral spines and five on dorsal spines. We then show that these characters can be used successfully for identifying fossil specimens. In particular, we present a case study in which we identify Synodontis cf. schall and Brachysynodontis cf. batensoda in the hominid-bearing sector Toros-Menalla (Late Miocene, northern Chad). We show that spine anatomy can be a powerful tool to recognise catfish species through time and thus to identify historical diversity pattern.     

Short and medium chain length chlorinated paraffins in UK human milk fat

Chlorinated paraffins (also called polychlorinated n-alkanes -- PCAs) are a class of industrial chemicals comprising chlorinated straight chain hydrocarbons. They have a wide range of applications and are now found in a range of environmental compartments. We analysed a total of 25 human milk-fat samples, donated by 18 individuals from the urban London and more rural Lancaster areas in the UK, for short chain PCAs (C(10)-C(13) sPCAs) and medium chain PCAs (C(14)-C(17) mPCAs), using gas chromatography-ECNI high-resolution mass spectrometry. Our study confirms that trace quantities of PCAs can reach human milk-fat. sPCAs were detected in all but four samples, while mPCAs were detected in all samples. The median sPCA concentration was 180 ng/g fat (range of 49 to 820 ng/g fat -- detected values only) and the median mPCA concentration was 21 ng/g fat (range of 6.2 to 320 ng/g fat). No differences were noted in ranges of observed values for either sPCAs or mPCAs between samples from London and Lancaster. Most samples also exhibited similar patterns of sPCAs and mPCAs. One sample exhibited a different pattern for sPCAs and mPCAs, an observation that may be related to differences in exposure or biological factors for this individual.     

Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method

More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste polymers cause serious environmental problems. Burning polymers for recycling is not practiced since poisonous gases are released during the burning process. Particularly, polyvinyl chloride (PVC) materials among waste polymers generate hazardous HCl gas, dioxins containing Cl, etc., which lead to air pollution and shorten the life of the incinerator. In addition, they make other polymers difficult to recycle.Both polyethylene terephthalate (PET) and PVC have densities of 1.30–1.35 g/cm³ and cannot be separated using conventional gravity separation techniques. For this reason, polymer recycling needs new techniques. Among these techniques, froth flotation, which is also used in mineral processing, can be useful because of its low cost and simplicity.The main objective of this research is to recycle PET and PVC selectively from post-consumer polymer wastes and virgin polymers by using froth flotation. According to the results, all PVC particles were floated with 98.8% efficiency in virgin polymer separation while PET particles were obtained with 99.7% purity and 57.0% efficiency in post-consumer polymer separation.     

Industrial and wildfire aerosol pollution over world heritage Lake Baikal

Lake Baikal is the biggest reservoir of fresh water with unique flora and fauna; presently it is negatively affected by climate change, water warming, industrial emissions, shipping, touristic activities, and Siberian forest fires. The assessment of air pollution - related Baikal's ecosystem damage is an unsolved problem. Ship, based expedition exploring the Baikal atmospheric aerosol loading, was performed over the lake area in July 2018. We combine the aerosol near - water and vertical distributions over the Lake Baikal basin with meteorological observations and air mass transportation simulations. Lidar sounding of aerosol fields in the troposphere assesses the atmospheric background in the pristine areas and the pollution during fire-affected periods. Aerosol optical properties (scattering and spectral absorption) converted to the particle number size, black carbon (BC) mass, and Absorption Angstrom Exponent (AAE) provide the inside into aerosol characterization. Transport of industrial emissions from Krasnoyarsk and Irkutsk regions, and wildfire plumes from Republic of Yakutia relates the pollution sources to the increased concentrations of fine particle numbers, PM₁₀ and BC mass over Southern and Northern/Central Baikal, respectively. The highest PM₁₀ and BC are associated to the harbor and touristic areas of intensive shipping and residential biomass burning. Deposition estimates applied to aerosol data exhibit the pollution fluxes to water surface over the whole Baikal area. AAE marks the impact of coal combustion, residential biomass burning, and wildfires indicating the high pollution level of the Lake Baikal ecological system .     

Impact of urbanization on the concentrations and distribution of organic contaminants in boreal lake sediments

The main goal of this study was to evaluate the impacts of a middle-sized Finnish urban area on the quality of sediments in an adjacent boreal lake. We investigated the sources and distribution of organic pollutants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)) in the sediments from urban stormwater traps and from Lake Vesijärvi. Grab surface sediment samples were taken from Lake Vesijärvi at various distances (25–2,000 m) from four major stormwater drainage outlets and at 15 urban stormwater traps in areas with different degrees of urbanization. These samples were analysed for 16 PAHs and 28 PCBs with gas chromatography–mass spectrometry. The concentrations of pollutants in the lake sediments were elevated in the vicinity of the urban shore (∑PAH 3–16, ∑PCB up to 0.02–0.3 mg/kg dw) and decreased as a function of distance (∑PAH 0.1–2.5, ∑PCB 0.01–0.3 mg/kg dw at a distance of more than 500 m from the shore), whereas contamination levels in suburban areas were notably lower (∑PAH 0.1–3, ∑PCB?<?LOQ–0.03 mg/kg dw; did not decline with distance). Possible sources and pathways of contamination were also investigated. The majority of stormwater trap sediments contained predominantly asphalt-derived PAHs due to pulverized pavement. PAHs in lake sediments were of pyrogenic origin, including the combustion of gasoline, diesel and coal. Suggested pathways of lake contamination are urban runoff discharge, boat traffic and atmospheric deposition.     

Increase in remediation processes of oil‐contaminated soils

A study was conducted in the region of the Lena River, in northeast Russia, where oil‐contaminated soil remediation is compromised due to the reduced natural attenuation mechanisms in northern eco‐systems. The goal of the study was to analyze the effectiveness of different biological methods for remediating the permafrost soil cover contaminated with high concentrations of oil. For the remediation of the areas with approximately similar levels of contamination (in the range of 10 to 14 grams per kilogram [g/kg] of soil) different biological remediation schemes were applied: site 1: sowing plant seeds of meadow clover grass; site 2: introducing a consortium of hydrocarbon oxidizing microorganisms (HOM); and, site 3: introducing the same consortium of HOM with simultaneously sowing grass mixture. The third scheme, applied for the first time, led to the most favorable results, which might be explained by the synergistic effect based on the principle of positive inverse development.