Environmental contamination by plastics and microplastics is a recognised problem worldwide, and it is the focus of many research teams. In the quantification of microplastics in the environment (plastic items with dimensions between 1 μm and 5 mm), the search for shared and universally recognised protocols and methodologies is still ongoing. In this study, the use of a method for extracting microplastics from marine sediments based on density separation has been considered. Fifty studies were analysed to investigate the scenario of salts exploited during microplastic extraction. The most commonly used salts are NaCl (45.6%), ZnCl₂ (19.3%) and NaI (17.5%). Considerations related to cost, availability, hazards of the salts and thus the repeatability of the related extraction method are reported. In light of the findings, NaCl remains the most readily usable, economical and effective salt for the extraction of microplastics from marine sediments.

The need for quantitative molecular methods is growing in environmental, food, and medical fields but is hindered by low and variable DNA extraction and by co-extraction of PCR inhibitors. DNA extracts from Enterococcus faecium, seawater, and seawater spiked with E. faecium and Vibrio parahaemolyticus were tested by qPCR for target recovery and inhibition. Conventional and novel methods were tested, including Synchronous Coefficient of Drag Alteration (SCODA) and lysis and purification systems used on an automated genetic sensor (the Environmental Sample Processor, ESP). Variable qPCR target recovery and inhibition were measured, significantly affecting target quantification. An aggressive lysis method that utilized chemical, enzymatic, and mechanical disruption enhanced target recovery compared to commercial kit protocols. SCODA purification did not show marked improvement over commercial spin columns. Overall, data suggested a general need to improve sample preparation and to accurately assess and account for DNA recovery and inhibition in qPCR applications.

We assessed the capacity of real-time PCR markers to identify the origin of contamination in shellfish. Oyster, cockles or clams were either contaminated with fecal materials and host-associated markers designed from Bacteroidales or Catellicoccus marimammalium 16S RNA genes were extracted from their intravalvular liquid, digestive tissues or shellfish flesh. Extraction of bacterial DNA from the oyster intravalvular liquid with FastDNA spin kit for soil enabled the selected markers to be quantified in 100% of artificially contaminated samples, and the source of contamination to be identified in 13 out of 38 naturally contaminated batches from European Class B and Class C areas. However, this protocol did not enable the origin of the contamination to be identified in cockle or clam samples. Although results are promising for extracts from intravalvular liquid in oyster, it is unlikely that a single protocol could be the best across all bacterial markers and types of shellfish.

Coral, fish, plankton, and detritus samples were collected from coral reefs in Virgin Islands National Park (VIIS) and Virgin Islands Coral Reef National Monument (VICR) to assess existing contamination levels. Passive water sampling using polar organic chemical integrative samplers (POCIS) and semi-permeable membrane devices found a few emerging pollutants of concern (DEET and galaxolide) and polynuclear aromatic hydrocarbons. Very little persistent organic chemical contamination was detected in the tissue or detritus samples. Detected contaminants were at concentrations below those reported to be harmful to aquatic organisms. Extracts from the POCIS were subjected to the yeast estrogen screen (YES) to assess potential estrogenicity of the contaminant mixture. Results of the YES (estrogen equivalency of 0.17–0.31ng/L 17-β-estradiol) indicated a low estrogenicity likelihood for contaminants extracted from water. Findings point to low levels of polar and non-polar organic contaminants in the bays sampled within VICR and VIIS.

Sediment contamination poses a potential risk for both ecosystems and human health. Risk assessment is troublesome as sediments contain complex mixtures of toxicants, and traditional chemical analyses can neither provide information about potential hazards to organisms nor identify and measure all present contaminants. This work combines the use of the PLHC-1 cell line and the recombinant yeast assay (RYA) to assess the environmental quality of estuarine and coastal sediments. The application of multiple endpoints (cytotoxicity, generation of oxidative stress, presence of CYP1A inducing agents, micronucleus formation and estrogenicity) revealed that the organic extracts of those sediments affected by industrial activities or collected near harbours and untreated urban discharges showed significant cytotoxicity, micronuclei and CYP1A induction. The study highlights the usefulness of the applied bioassays to identify those sediments that could pose risk to aquatic organisms and that require further action to improve their environmental quality.

The effects of chemical speciation on mineralization of organic compounds was studied using citric acid as a model substance. The degradation of ¹⁴C-labeled Al-, Co-, Cu-, and Zn-citrate was followed in chemically well-defined media inoculated with mixed cultures of microorganisms (soil extracts from two soils). The degradation of citrate was completely inhibited when the acid was bound to Zn, Cu, or Co and partly inhibited when bound to Al. The mineralization of citrate as well as histidine was also followed by incubation of the complexes (Cu, Zn, Al) in the two soils. No effect of metals on the degradation of histidine was seen. The degradation of citrate in soils was also unaffected when complexed to Cu and Zn, whereas Al exerted an inhibited decomposition in both soils.

This study assessed the suitability of passive sampler extracts for use with a GC-MS-database rapid screening technique for around 940 organic chemicals. Chemcatcher™ passive sampler systems containing either Empore™ SDB-XC or C18FF disks were deployed at 21 riverine sites in and near Melbourne, Victoria, Australia, for a period of 28 days during September–October 2008. Methanolic elution of the SDB-XC and C18FF disks produced an extract that, after evaporation and inversion into hexane, was compatible with the GC-MS-database method enabling over 30 chemicals to be observed. The sources of the non-agricultural chemicals are still unclear, but this study was conducted in a relatively dry season where total rainfall was approximately 40 % lower than the long-term mean for the catchment during the study period. Thus, the risks may be greater in wetter seasons, as greater quantities of chemicals are likely to reach waterways as the frequency, extent and intensity of surface run-off events increase. This study provides valuable information for policy and decision-makers, both in Australia and other regions of the world, in that passive sampling can be conveniently used prior to analysis by multi-residue techniques to produce data to assess the likely risks trace organic chemicals pose to aquatic ecosystems.

The role of chemical interactions in shaping microbial communities has raised increasing interest over the last decade. Many benthic microorganisms are known to develop chemical strategies to overcome competitors, but the real importance of chemical interactions within freshwater biofilm remains unknown. This study focused on the biological and chemical mechanisms of an interaction involving two benthic microorganisms, an allelopathic filamentous green alga, Uronema confervicolum, and a common diatom, Fistulifera saprophila. Our results showed that functions critical for benthic phototrophic microorganisms were inhibited by U. confervicolum extracts. Growth, cell motility, adhesion, and photosynthetic activity were impaired at extract concentrations ranging between 5 and 20 μg ml⁻¹. The adhesion inhibition was mediated by intracellular nitric oxide (NO) induction. A bioassay-guided fractionation of the extract with HPLC helped to identify two C18 fatty acids present in the growth-inhibiting fractions: linoleic (LA) and α-linolenic (LNA) acids. These compounds represented 77 % of the total free fatty acids of U. confervicolum and were present in the culture medium (1.45 μg l⁻¹ in total). Both could inhibit the diatom growth at concentrations higher than 0.25 μg ml⁻¹, but had no effect on cell adhesion. The discrepancy between the effective concentrations of fatty acids and the concentration found in culture medium may be explained by the presence of high-concentration microenvironments. The compounds involved in adhesion inhibition remain to be identified. Though further experiments with complex biofilms are needed, our results suggest that U. confervicolum may participate to the control of biofilm composition by inhibiting diatom adhesion.

Aluminium (Al) speciation is a characteristic that can be used as a tool for describing the soil acidification process. The question that was answered is how tree species (beech vs spruce) and type of soil horizon affect Al speciation. Our hypotesis is that spruce and beech forest vegetation are able to modify the chemical characteristics of organic horizon, hence the content of Al species. Moreover, these characteristics are seasonally dependent. To answer these questions, a detailed chromatographic speciation of Al in forest soils under contrasting tree species was performed. The Jizera Mountains area (Czech Republic) was chosen as a representative mountainous soil ecosystem. A basic forestry survey was performed on the investigated area. Soil and precipitation samples (throughfall, stemflow) were collected under both beech and spruce stands at monthly intervals from April to November during the years 2008–2011. Total aluminium content and Al speciation, pH, and dissolved organic carbon were determined in aqueous soil extracts and in precipitation samples. We found that the most important factors affecting the chemistry of soils, hence content of the Al species, are soil horizons and vegetation cover. pH strongly affects the amount of Al species under both forests. Fermentation (F) and humified (H) organic horizons contain a higher content of water extractable Al and Al³⁺ compared to organo-mineral (A) and mineral horizons (B). With increasing soil profile depth, the amount of water extractable Al, Al³⁺ and moisture decreases. The prevailing water-extractable species of Al in all studied soils and profiles under both spruce and beech forests were organically bound monovalent Al species. Distinct seasonal variations in organic and mineral soil horizons were found under both spruce and beech forests. Maximum concentrations of water-extractable Al and Al³⁺ were determined in the summer, and the lowest in spring.