Cadmium (Cd) is a widespread contaminant in aquatic systems and has a variety of toxicological implications on freshwater microorganisms. In this study, the green algae Scenedesmus obliquus was exposed to increasing Cd concentrations that inhibited growth by 20% (12.6 μmol L⁻¹), 30% (39.8 μmol L⁻¹) and 40% (83.2 μmol L⁻¹) and the metabolite profiles of released and cellular biomolecules were explored using an untargeted direct infusion high resolution Fourier transform ion cyclotron resonance mass spectrometry approach. In Cd untreated cultures, intrinsic differences in composition existed between released biomolecules and freeze-dried cells. Based on putatively characterized compound groups, a greater proportion of Cys-GSH isomers and carboxyamides were present in exudates whereas sugar isomers and phosphonic acids comprised most cellular metabolites. In cultures exposed to 83.2 μmol L⁻¹ Cd, an overall shift in metabolomic response across both released biomolecules and cellular components resulted in an increase of lipid-based esters, and Cys-GSH isomers. These two important metabolites are used in antioxidant defense mechanisms and reactive oxygen species prevention during cellular stress. The diversity of metabolites also decreased as Cd concentrations increased when compared to untreated cultures, suggesting that overall metabolites specialize upon metal stress. We show systemic shifts from sugar and carboxylic isomers to specialized proteins and lipid isomers to help S. obliquus cope with stress. These findings highlight the potential use of this green algae as a potential biosorbent and sheds light into the metabolomics of Cd toxicology and insights into microbial metal adaptation.

Increasing numbers of studies have demonstrated the existence of nanoplastics (1–999 nm) in the environment and commercial products, but the current technologies for detecting and quantifying nanoplastics are still developing. Herein, we present a combination of two techniques, e.g., scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), to analyze submicron-sized plastics. A drop-casting of a 20-nL particle suspension on a Piranha solution-cleaned silicon wafer with dry ice incubation and subsequent freeze-drying was used to suppress the coffee-ring effect. SEM images were used to quantify particles, and this technique is applicable for 0.195–1.04-μm polystyrene (PS), 0.311-μm polyethylene terephthalate (PET), and 0.344-μm polyethylene (PE) at a minimum concentration of 2.49 × 10⁹ particles/mL. ToF-SIMS could not quantify the particle number, while it could semi-quantitatively estimate number ratios of submicron PE, PET, polyvinyl chloride (PVC), and PS particles in the mixture. Analysis of submicron plastics released from three hot water-steeped teabags (respectively made of PET/PE, polylactic acid (PLA), and PET) was revisited. The SEM-derived sizes and particle numbers were comparable to those measured by a nanoparticle tracking analysis (NTA) regardless of whether or not the hydro-soluble oligomers were removed. ToF-SIMS further confirmed the number ratios of different particles from a PET/PE composite teabag leachate. This method shows potential for application in analyzing more-complex plastic particles released from food contact materials.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous analysis of 6 ectoparasiticides – 2 synthetic pyrethroids (deltamethrin, cypermethrin) and 4 macrocyclic lactones (abamectin, doramectin, ivermectin and eprinomectin) in biosolids. The method was used to investigate the occurrence of these ectoparasiticides in beef cattle feedlot wastes in Australia from 5 commercial feedlot operations which employ varying waste management practices. Deltamethrin and cypermethrin were not detected in any of the samples while abamectin, ivermectin, doramectin and eprinomectin were detected in some of the samples with concentrations ranging from 1 to 36 μg/kg dry weight (d.w.) freeze dried feedlot waste. Levels of macrocyclic lactones detected in the feedlot wastes varied and were dependent on sample type. The effect of seasonal variations and waste management practices were also investigated in this study.

Natural mosses have been employed as reactive and accumulative indicators of atmospheric pollutants. Using the denitrifier method, the concentration, δ¹⁵N and δ¹⁸O of moss nitrate (NO₃ ⁻) were measured to elucidate the sources of NO₃ ⁻ trapped in natural mosses. Oven drying at 55–70 °C, not lyophilization, was recommended to dry mosses for NO₃ ⁻ analyses. An investigation from urban to mountain sites in western Tokyo suggested that moss [NO₃ ⁻] can respond to NO₃ ⁻ availability in different habitats. NO₃ ⁻ in terricolous mosses showed isotopic ratios as close to those of soil NO₃ ⁻, reflecting the utilization of soil NO₃ ⁻. Isotopic signatures of NO₃ ⁻ in corticolous and epilithic mosses elucidated atmospheric NO₃ ⁻ sources and strength from the urban (vehicle NOₓ emission) to mountain area (wet-deposition NO₃ ⁻). However, mechanisms and isotopic effects of moss NO₃ ⁻ utilization must be further verified to enable the application of moss NO₃ ⁻ isotopes for source identification.

Microplastics are gaining worldwide attention due to their omnipresence. The marine environment is one of the most affected systems; especially the sediment compartment. Microplastic separation from the sediment matrix is the first step to evaluate its abundance and availability. Nevertheless, a lack of consistency in extraction protocols is a fact. This paper describes the optimization of the microplastic extraction procedure from marine sediments. The Plackett-Burman saturated factorial design was used to identify the significant factors and to select optimum working conditions. With this purpose, the following variables were studied: the number of extractions; the amount of sediment; the settling time; the density separation solution volume; the agitation time and the suitability of using wet or freeze-dried sediment. The Plackett-Burman design has revealed that the most statistically significant variables were sediment mass and agitation time. The optimized method was applied for two marine sediments collected in the Mar Menor Lagoon.

The Lenga Estuary is a small brackish wetland located southwest of San Vicente Bay, Region VIII, Chile. Surface sediment from nine sites in the estuary were analysed for PAHs and compared to Sediment Quality Guidelines (SQG). Sediment samples were freeze dried and soxhlet extracted for 16h using DCM. Identification and quantification was carried out by HPLC. Organic carbon was also determined. Results showed total PAH concentrations ranged from 290 to 6118 (2025±1975)ngg⁻¹ d.w. (2025±1975). Results for organic carbon percentages ranged from 1% to 7%. Statistical analysis showed a significant positive correlation (Pearson test) between organic carbon percentage PAHs. Comparison of contaminant levels and international Sediment Quality Guidelines (SQG) (ERL and ER) suggested that sediment of the Lenga estuary did not show any ecotoxicologial risk for benthic organisms where high levels of PAHs were detected. Monitoring of this and other contaminants is recommended in Chile.

This paper aims to identify the concentrations of PAHs in the sediments of four coastal zones in Lebanon and determine their possible sources and effects. For each region (Tripoli, Jounieh, Dora, and Tyre), sampling, lyophilization, Soxhlet extraction, rotary evaporation, and gas chromatography were performed on 11, 10, 7, and 11 samples, respectively. The total PAHs concentrations ranged from 1.22 to 731.93μg/kg dry weight. The lowest concentrations were found in Tyre and the highest in Dora and Jounieh. The level of PAHs was classified as low to moderate and their source was mainly pyrogenic.

Analysis of 35 parental and alkylated homologues of PAHs (Polycyclic Aromatic Hydrocarbons) was carried out in eleven marine sediment samples collected along a central transect in the biggest Galician ría. The samples were collected using a box-core dredge and, after freeze-drying, were kept frozen until analysis. The sediments were extracted by PLE (Pressurized Liquid Extraction) procedure and the quantification of PAHs was performed using gas chromatography coupled to mass spectrometry (GC–MS) with the aid of deuterated PAH internal standards. The total concentration of studied PAHs (Σ35PAHs) ranged from 44.8 to 7901ngg−1 dry weight (d.w.). The highest PAH concentrations were found in sediments collected near the harbour (7901ngg−1) and the cleanest positions were located in the outer zone of the ría.To date, these results are the first data presented in the area so they could be used for regular monitoring and control of future pollution episodes.

Various oil spill cleanup sorbents have good hydrophobicity and oil separation efficiency, but their practical use has been limited due to the difficult and costly fabrication procedure. The research aims towards material development using the consumption of lignocellulosic agricultural residue for isolating cellulose nanofiber and its forward use to construct a 3D porous structure. A simple freeze-drying technique was used to assemble low-density porous structure. The biodegradable polylactic acid coating was used to alter the wettability from hydrophilic to hydrophobic and the maximum water contact angle value was around 120°. The prepared coated samples were testified for a series of oil/organic solvents-water mixtures. The sorption capacity was in the range of 28–70 g/g. The prepared aerogels were efficiently reused for at least 10 cycles. Developed material was used in continuous oil-water separation to remove oil from the water's surface. The cost analysis was estimated for scaleup production in the future.

Problems from water contamination of oil and organic solvents have become more serious in recent years. We report research describing the fabrication of a hydrophobic sponge aerogel from pomelo peel for oil/water separation. Hydrophobic pomelo peel sponge aerogel (HPSA-1) was synthesized via dispersion, freeze-drying, and chemical vapor deposition (salinization) with hexadecyltrimethoxysilane. The morphology and chemical properties of the sponge aerogels were analyzed by scanning electron microscope and Fourier transform infrared. HPSA-1 was examined for use to remove some oils and organic solvents floating on water. HPSA-1 aerogels had medium absorption capacity; however, removal ability and the absorption of HPSA-1 were saturated at exposure times of 10 s. Diesel oil was the highest absorbate with absorption capacity (3.08–3.64 g g⁻¹) and recovery percent of 48.15–59.46%. Removal abilities of selected oils and organic solvents floating on water using HPSA-1 at 10 s were investigated. HPSA-1 absorbed the oils and organic solvents in the range of 1.98–3.85 g g⁻¹, with absorption levels depending on their types. Of the oils tested, palm oil had the highest absorption level with HPSA-1 removal at 3.85 g g⁻¹ and 57.5%, respectively.